Radiology Flashcards
A 56-year-old man presents to the emergency room
with 1 week of altered mental status. His medical
history is significant for a glioblastoma treated with
resection followed by temozolomide therapy and
whole brain radiation 1 year ago. An MRI is performed, and contrast-enhanced, diffusion-weighted,
and apparent diffusion coefficient sequences are
shown in these images. Perfusion maps (not shown)
demonstrate decreased relative cerebral blood volume. What is the likely cause of his new symptoms?
A. Radiation necrosis
B. Recurrent glioblastoma
C. Secondary tumor caused by chemotherapy
regimen
D. Encephalomalacia from tumor resection
A. Radiation necrosis
Radiation necrosis typically presents with higher apparent diffusion coefficient (ADC) values compared with tumor recurrence, which tends to show restricted diffusion and therefore lower signal in the solid enhancing components. On perfusion MRI,
radiation necrosis demonstrates decreased relative cerebral blood volume (rCBV) in contrast to highgrade tumors. Finally, this patient is 1 year from his radiation therapy, which is a peak time for radiation necrosis to appear (usually between 12 and 24 months). (B) A recurrent glioblastoma would tend to have a low ADC signal and increased perfusion on rCBV maps. (C) Secondary malignancies following temozolomide (an alkylating agent) have been reported but are a rare occurrence. These malignancies usually are hematologic. Glioblastoma would be much more likely than a secondary malignancy, given its aggressive nature and expected eventual recurrence. (D) Encephalomalacia would be apparent by parenchymal volume loss and should not
show nodular enhancement or restricted diffusion. Some (usually nonnodular) enhancement may be present around the resection cavity due to granulation tissue
The lesion shown in these images depicts a(n):
A. Optic nerve glioma
B. Meningioma
C. Chordoma
D. Esthesioneuroblastoma
D. Esthesioneuroblastoma
Esthesioneuroblastomas (olfactory neuroblastomas) are rare, malignant tumors of the superior nasal cavity and anterior skull base. Treatment strategies vary widely and include surgery, radiotherapy, and/or chemotherapy. The ideal treatment
modality has yet to be determined. Esthesioneuroblastomas tend to exert mass effect on the orbits, optic nerves, and optic chiasm, and may result in proptosis. They can occur in the frontal sinus and have variable intracranial extension. They homogeneously enhance on contrasted T1 sequences and
appear moderately hyperintense on T2 sequences. (A) An optic nerve glioma would infiltrate and expand the optic nerve. As seen in the second image, there is stretching of the optic nerve due to mass effect and proptosis, but the tumor itself does not involve the optic apparatus. (B) Anterior skull base meningiomas also demonstrate avid enhancement and occasionally can extend into the olfactory recess. They may present with a dural tail
and hyperostosis; however, the epicenter of the mass in this case is in the sinonasal cavity without a significant intracranial dural component. This makes a meningioma unlikely. Esthesioneuroblastomas often do extend intracranially, in which case a “waist” at the level of the cribriform plate and cysts at the brain–tumor interface are strongly suggestive of such diagnosis. (C) Skull base chordomas usually are located in the anterior clivus but
rarely may extend to the nasal cavity. Primary
chordomas in the nasal cavity and maxilla without clival involvement are extremely rare. Chordomas usually demonstrate more heterogeneous enhancement than esthesioneuroblastomas on contrasted
T1 sequences and are very hyperintense on T2
sequences.
What likely is associated with the imaging findings
on the MR susceptibility-weighted imaging (SWI)
sequence shown in these images?
A. Shearing injury from rotational acceleration
B. β-amyloid peptide deposits
C. Mutations in the CCM1 gene
D. Long bone fractures
D. Long bone fractures
Long bone fractures can result in fat embolism,
which appears as tiny foci of susceptibility artifact
that preferentially may be located at the gray matter–white matter interface or diffusely distributed
as in this case. Fat embolism may be accompanied
by scattered foci of restricted diffusion. (A) Diffuse
axonal injury is due to shearing forces from rotational acceleration. Areas of hemorrhage can be
detected on susceptibility-weighted imaging (SWI)
sequences and tend to be located in the gray
matter–white matter junction, corpus callosum,
and brainstem. Linear SWI signal loss often can be
seen along the white matter tracts. (B) β-amyloid
peptide deposits are related to cerebral amyloid
angiopathy (CAA). SWI may show multiple foci
of signal loss located peripherally in a cortical/
subcortical distribution rather than diffusely as
in this case. Patients also can have superficial siderosis and present with subarachnoid hemorrhage.
(C) Mutations in the CCM1, CCM2, and CCM3 genes
can be seen in familial cavernous malformation
syndromes. Lesions usually are more randomly
distributed and not as evenly sized as in the current case.
A 22-year-old man without a significant medical
history presents with progressive midthoracic pain.
An MRI examination of the spine is shown in these
images. What is the most likely diagnosis?
A. Astrocytoma
B. Ependymoma
C. Metastasis
D. Tumefactive demyelination
A. Astrocytoma
Astrocytomas in the spinal cord are most common in children but also may occur in adults. The
majority of them are histologically low grade and
slow growing, and may result in bone remodeling.
Half of astrocytomas are of the pilocytic subtype
and are relatively well defined, whereas the
remainder are infiltrative. They commonly present
as expansile masses with variable degrees of illdefined enhancement, although some tumors may
not enhance. (B) Ependymomas are more common in adults. Compared with astrocytomas, their
enhancement more frequently is well defined, and
they more commonly are associated with cystic
changes or hemorrhage. They are located more
centrally, as they arise from the ependyma, but
such distinction becomes difficult in larger tumors.
(C) Metastases to the cervical spine typically are
more focal than and not as expansile as the demonstrated lesion. It would be highly unusual for a
patient of this age to present with a spinal cord
metastasis without a known primary malignancy.
(D) Tumefactive demyelination is more common
in the brain. Demyelinating lesions may be seen in
the spinal cord and may be related to acute disseminated encephalomyelitis (more common in
the cervical spine), neuromyelitis optica (which
may result in longitudinally extensive transverse
myelitis), and multiple sclerosis (usually with small
lesions centered in the peripheral white matter
and only rarely extending over long segments when
confluent). The appearance of the lesion in question is too expansile and is not compatible with a
demyelinating or inflammatory process.
A neonate underwent an MRI of his brain, shown
in this image. What may be an associated finding?
A. Interhemispheric cysts
B. Collapse of ventricular atria and occipital horns
C. Low-riding third ventricle
D. Curvilinear pericallosal lipomas
A. Interhemispheric cysts
The image accompanying the question shows
dysgenesis of the corpus callosum with incomplete
formation of the cingulate gyrus. Dorsal or occasionally anterior interhemispheric cysts are a common finding. (B) Colpocephaly (dilatation of the
atria and occipital horns of the lateral ventricles) is
a characteristic secondary finding in dysgenesis of
the corpus callosum. (C) Patients with dysgenesis
of the corpus callosum can have a “high-riding”
third ventricle. Additional findings include bundles of Probst (white matter that failed to cross the
midline) and incomplete rotation of the hippocampi. (D) Tubulonodular lipomas have a significantly increased incidence of associated anomalies
compared with curvilinear ones.
What is a characteristic of the lesion depicted in
the MRI study shown in these images?
A. Results from premature disjunction of the
cutaneous ectoderm from the neuroectoderm
during neurulation
B. Infiltrative hypercellular lesion with variable
degrees of mitosis/atypia
C. Results from clonal transformation of cells of
B-cell origin
D. May be associated with endolymphatic sac
tumors, ren
A. Results from premature disjunction of the
cutaneous ectoderm from the neuroectoderm
during neurulation
Postcontrast sagittal T1 and short tau inversion
recovery (STIR) images show a large lobulated
mass that appears to be intradural and at least partially intramedullary. Although most of the mass
is hyperintense on T1, these areas fully suppress
on STIR images, indicating that this signal is related
to fat rather than contrast enhancement. Spinal
lipomas follow fat signal on all sequences, and subcutaneous fat can be used as an internal control.
Embryologically, these lesions result from premature disjunction of the cutaneous ectoderm from
the neuroectoderm during neurulation, whereby
the open neural tube becomes exposed to the
ingrowth of mesodermal tissues. Patients may
experience slowly progressing paresis, spasticity,
or sensory loss depending on the extent and location of the lesion. (B) An infiltrative hypercellular
lesion with variable degrees of mitosis/atypia would
describe a neoplastic process such as an astrocytoma, which may or may not show enhancement.
(C) Clonal transformation of cells of B-cell origin
would result in lymphoma (e.g., Hodgkin). These
lesions are rare in the spinal cord and usually
enhance. (D) Hemangioblastomas are very vascular and avidly enhance. They can occur in the spinal cord or leptomeninges. They may be associated
with endolymphatic sac tumors, renal cell carcinomas, retinal angiomas, pheochromocytomas, and
cystic lesions.
A 30-year-old woman with a history of recurrent
genital and oral aphthae and erythema nodosum
underwent an MRI of the brain. What is a likely
imaging finding in this patient?
A. Enhancing lesion involving the brainstem
B. Fluid-attentuated inversion recovery (FLAIR)
hyperintense lesion sparing red nuclei and
substantia nigra
C. Lesions with a leading edge of restricted
diffusion
D. Lesions involving the pulvinar and dorsomedial thalamic nuclei
E. Lesions with an incomplete rim of enhancement
A. Enhancing lesion involving the brainstem
Manifestations of Behçet disease in the central
nervous system are varied. The brainstem is the
most commonly affected, and lesions can be focal
or multifocal. There usually is associated edema
and contrast enhancement, particularly in the acute
phase. Patients also can present with meningoencephalitis and nonspecific white matter lesions.
(B) T2/FLAIR hyperintensity in the brainstem sparing the red nuclei and substantia nigra commonly
is described in Wilson disease. (C) A leading edge
of restricted diffusion can be seen in large or new
lesions in progressive multifocal leukoencephalopathy. (D) Lesions involving the pulvinar and
dorsomedial thalamic nuclei are characteristic
of variant Creutzfeldt-Jakob disease. (E) Active
demyelination can present with an incomplete
rim of enhancement.
A 54-year-old man underwent an MRI of the spine.
Sagittal and axial postcontrast T1-weighted images
are shown in these images. What is the patient’s
likely diagnosis?
A. Leptomeningeal metastasis
B. Neurofibroma
C. Schwannoma
D. Meningioma
D. Meningioma
The demonstrated homogeneously enhancing
dural-based mass along the left ventral aspect of
the spinal canal at the level of C2 is most consistent
with a meningioma. It is more common in females
and, when in the spine, it most frequently occurs
in the thoracic region. It nearly always is completely intradural, but also may protrude through
the neural foramina, resulting in a “dumbbell”
configuration and thus may look similar to schwannomas. (A) Leptomeningeal metastases usually
develop along the pial surface of the cord and spinal nerves. The lesion in question is dural based.
(B) Neurofibromas may be indistinguishable from
schwannomas by imaging. They may show a socalled target sign with central hypointensity on
T2-weighted sequences due to a fibrocollagenous
core. (C) Schwannomas tend to enhance more
avidly and heterogeneously than meningiomas,
particularly due to the presence of cystic changes
and hemorrhages in larger lesions. They follow the
course of the involved nerve and do not show a
dural base. Although not entirely specific, they can
extrude through and expand the neural foramina,
resulting in a “dumbbell” configuration.
The lesion shown in this image (arrow) can result
from injury to what structure?
A. Central tegmental tract
B. Lateral lemniscus
C. Spinothalamic tract
D. Reticulospinal tract
A. Central tegmental tract
The axial FLAIR image accompanying the question demonstrates hyperintensity of the left inferior olivary nucleus in a patient with hypertrophic
olivary degeneration. This can be caused by a
lesion involving the triangle of Guillain-Mollaret,
a circuit connecting the dentate, red, and inferior
olivary nuclei. Efferent fibers from the dentate
nucleus ascend via the superior cerebellar peduncle
and decussate to the contralateral red nucleus, from
which fibers project inferiorly to the ipsilateral
inferior olivary nucleus through the central tegmental tract. Patients characteristically present
with palatal tremors. (B) The lateral lemniscus is
not part of the Guillain-Mollaret triangle. Bilateral
lesions are associated with hearing loss. (C) The
spinothalamic tract is a sensory pathway that
transmits pain and temperature sensation from the
spinal cord to the thalami. (D) The reticulospinal
tract transmits information from the reticular formation in the pons and medulla to the spinal cord.
It is not part of the Guillain-Mollaret triangle.
Axial T2 and postcontrast T1-weighted imaging of
the lumbar spine are shown in these images. To
what does the abnormality indicated by the arrow
correspond?
A. Disk protrusion
B. Epidural scar
C. Disk extrusion
D. Epidural abscess
E. Sequestered disk
B. Epidural scar
The axial T2 images accompanying the question show hypointense tissue projecting into the
right paracentral zone. This tissue shows diffuse
enhancement on the postcontrast image, and therefore is most consistent with scar. Note the evidence
of a prior right-sided laminotomy. (A, C, E) A disk
protrusion or extrusion or a sequestered disk
should not enhance. (D) There is no fluid collection
with peripheral enhancement to suggest an epidural abscess.
A 12-year-old girl is brought to the emergency
department in an obtunded state following an
episode of seizures. Based on these images, what
is the diagnosis?
A. Cortical venous thrombosis
B. Deep venous thrombosis
C. Mitochondrial encephalopathy
D. Hypoxic ischemic encephalopathy
E. Arterial infarction
B. Deep venous thrombosis
The sagittal noncontrast T1-weighted image
(right) accompanying the question shows increased
signal in the straight sinus, vein of Galen, and
internal cerebral veins due to thrombosis. Also note
the profound hypointensity of the thalami compared with the brain. The axial FLAIR image (left)
shows marked swelling of the basal ganglia and
thalami bilaterally due to venous infarction. Risk
factors for deep venous thrombosis include severe
dehydration and other hypercoagulable states such
as pregnancy, malignancy, and sepsis. Venous
infarction occurs in a nonarterial distribution and
may be complicated by hemorrhage. (A) Cortical
venous thrombosis may lead to lobar infarctions
sparing the deep gray structures. (C) Leigh disease
is a mitochondrial encephalopathy that may affect
the basal ganglia, periaqueductal gray, and cerebral peduncles. Changes in the putamina seem
to be a consistent feature. (D) Hypoxic ischemic
encephalopathy can occur following hypoxia, such
as in cardiorespiratory arrest, drowning, or various
forms of asphyxiation. In older children and adults,
the watershed zones initially may be affected after
mild insults, with more severe cases involving gray
matter structures, particularly the cerebral cortex,
basal ganglia, and hippocampi. Perinatal hypoxic
ischemic injury preferentially may affect the thalami, brainstem, and perirolandic cortex. There may
be white matter involvement in the setting of
global ischemia. (E) The imaging abnormalities in
this case do not follow an arterial distribution.
A woman underwent a head CT, shown in these
images. What is the likely diagnosis?
A. Infiltrative tumor
B. Acute infarct
C. Intracranial hemorrhage
D. Meningitis
C. Intracranial hemorrhage
There is a hemispheric subdural hematoma along
the right convexity that is isodense to the cortex.
This appearance can occur depending on when the
patient is imaged, as the density of blood decreases
over time and, at some point, will have the same
attenuation as cortex. The best way to recognize
such hematomas is to identify their associated mass
effect and the displacement of the darker white
matter, which can be seen medial to the hematoma. (A) An infiltrative tumor would involve the
cortex and white matter more diffusely. The demonstrated process is centered in the extra-axial space
and is subdural due to its overall crescentic shape
and the fact that it crosses sutures. (B) A noncontrast head CT in acute infarct may be normal, particularly in the first 6 hours after ictus. Early
findings include a hyperdense middle cerebral
artery territory, loss of gray matter–white matter
distinction in the basal ganglia or peripheral brain,
and loss of the insular ribbon. (D) The majority
of noncontrast head CT studies in meningitis are
normal, and patients sometimes may present with
hydrocephalus as an isolated finding. Areas of
edema due to cerebritis or intra- and extra-axial
abscesses may be seen in complicated meningitis.
Contrast studies, in particular MRI, may be able to
show the presence of leptomeningeal disease.
A boy with truncal ataxia and abnormal eye movements undergoes an MRI of the brain, which shows
continuation of the cerebellar hemispheres and
dentate nuclei and absence of the vermis. What is
the most likely diagnosis?
A. Pontine tegmental cap dysplasia
B. Rhombencephalosynapsis
C. Joubert syndrome
D. Dandy-Walker malformation
B. Rhombencephalosynapsis
Rhombencephalosynapsis is characterized by
an absent vermis and midline continuation of
the dentate nuclei, cerebellar hemispheres, and
superior cerebellar peduncles. It can be seen in
isolation or associated with other malformations
such as the VACTERL spectrum and Gomez-LopezHernandez syndrome. (A) Pontine tegmental cap
dysplasia is a rare hindbrain malformation that includes dysplasia of the cerebellar vermis, lateralized superior cerebellar peduncles, ectopic dorsal
transverse pontine fibers (tegmental cap), flattened ventral pons, absence of the inferior olives,
and absence or near absence of the middle cerebellar peduncles. (C) Joubert syndrome is characterized by vermian hypoplasia or aplasia and lack of
decussation of the superior cerebellar peduncles,
resulting in a “molar tooth” appearance. (D) A
Dandy-Walker malformation can result in cystic
enlargement of the posterior fossa in communication with the fourth ventricle. The vermis is
hypoplastic, but there is no continuation of the
cerebellar structures.
A 38-year-old man who sustained a gunshot wound
to the head underwent an emergent CT scan,
shown in this image. What finding portends the
worst prognosis?
A. Presence of both entry and exit wounds
B. Involvement of the inner and outer tables of
the calvaria
C. Bullet tract crossing the deep midline structures
D. Presence of metallic fragments along the bullet trajectory
E. Presence of an open comminuted fracture
C. Bullet tract crossing the deep midline structures
Various studies consistently have shown that
bullet tracts crossing the midline (i.e., bihemispheric involvement) are associated with increased
mortality and worse functional outcomes in those
patients who survive, although there are recent
data suggesting that individuals with isolated
bifrontal involvement may have a relatively better
prognosis. Other significant negative prognostic
factors include brainstem involvement, posterior
fossa injuries, transventricular injuries, low Glasgow
Coma Scale score, nonreactive pupils, and older age.
(A) The presence of both entry and exit wounds
is not a significant predictor of worse outcomes.
(B) Involvement of the inner and outer tables of
the calvaria is not a significant predictor of worse
outcomes. (D) The presence of bullet fragments
is not a significant predictor of worse outcomes.
(E) The presence of an open comminuted fracture
is not a significant predictor of worse outcomes.
The axial CT scan in this image shows the level of
termination of bilateral cerebral deep brain stimulation leads. What is the anatomic location of these
leads?
A. Globus pallidus interna
B. Subthalamic nuclei
C. Ventral intermediate nuclei
D. Red nuclei
A. Globus pallidus interna
The image accompanying the question shows
bilateral deep brain stimulator leads terminating
in the globus pallidus interna (GPi) that are used
to treat motor fluctuations in advanced medication
resistant Parkinson disease or levodopa induced
dyskinesia. (B) The subthalamic nuclei are an alternative target for deep brain stimulation in Parkinson disease. They are located at a lower level
superior to the substantia nigra, lateral to the red
nuclei, and medial to the internal capsule. (C) The
ventral intermediate nuclei are located in the ventral thalami just lateral to the red nuclei. They are a
common target for the treatment of essential tremors. (D) The red nuclei are paired, round T2 hypointense structures located in the rostral midbrain.
A man is reported to have a “string of pearls”
appearance on his angiogram. What is the likely
diagnosis?
A. Severe carotid artery stenosis
B. Dural arteriovenous fistula
C. Fibromuscular dysplasia
D. Arteriovenous malformation
E. Carotid artery dissection
C. Fibromuscular dysplasia
The medial type of fibromuscular dysplasia is by
far the most common and can show a “string of
pearls” appearance on angiography. The same descriptor also is sometimes used for cerebral vasculitis, which can show areas of alternating segmental
vascular stenoses and dilatation. (A) A “string sign”
sometimes is described with severe carotid artery
stenosis due to a very thin column of contrast flowing through the narrowed segment. (B) The “buzz”
term for a dural arteriovenous fistula is “retrograde cortical venous drainage” or “cortical venous
reflux,” which is associated with more aggressive
behavior and an indication for emergent treatment. (D) Arteriovenous malformations display early
draining veins and the presence of a nidus sometimes with venous or arterial aneurysms. (E) Carotid artery dissections can show a “string sign” in the narrowed segment; however, dissection of the internal carotid artery typically is associated with a “flame shape” configuration when it occurs just above the level of the carotid bulb.
A sagittal T2-weighted image of a patient with a
tethered cord is shown in this image. What is a
characteristic of the pathology represented here?
A. Reduced risk following folic acid supplementation
B. Associated with Chiari 2 malformations
C. Secondary to premature disjunction of the
neural ectoderm
D. Most cases are familial
C. Secondary to premature disjunction of the
neural ectoderm
Lipomyelomeningoceles, lipomyeloceles, and
lipomas are secondary to premature disjunction of
the neural ectoderm from the cutaneous ectoderm.
(A) Studies have not found a decreased incidence of
lipomyelomeningoceles following folic acid supplementation, suggesting that the pathogenesis
is different from that of other neural tube defects.
(B) Open myelomeningoceles are the sine qua non
of Chiari 2 malformations. Closed defects covered
by skin such as this one do not result in Chiari 2
malformations. (D) The vast majority of lipomyelomeningoceles are sporadic. A few familial cases
have been reported, but they are exceedingly rare.
What is the origin of the lesion on the contrastenhanced T1 image shown here?
A. Facial nerve
B. Vestibular nerve
C. Aberrant carotid artery
D. Inferior petrosal sinus
A. Facial nerve
There is an avidly enhancing mass involving the
right geniculate ganglion as well as the labyrinthine and canalicular segments of the right facial
nerve compatible with a schwannoma. The vast
majority of intracranial schwannomas arise from
the vestibular nerve followed by the trigeminal and
facial nerves. (B) A vestibular schwannoma would
not involve the facial nerve canal or geniculate
ganglion. (C) An aberrant internal carotid artery is
seen more inferiorly as a more lateral extension
of the internal carotid artery beyond the cochlear
promontory. It may appear as a pulsating “mass”
on clinical exam. (D) The inferior petrosal sinus
is located along the inferior aspect of the petrous
bone. It drains blood from the cavernous sinus into the jugular vein
A falcotentorial arteriovenous malformation is
noted to have its primary vascular supply from an
enlarged tentorial artery. What is the usual origin
of this vessel?
A. Meningohypophyseal trunk
B. Inferolateral trunk
C. Neuromeningeal trunk
D. Posterior cerebral artery
A. Meningohypophyseal trunk
The tentorial artery (of Bernasconi and Cassinari) is the most constant branch of the meningohypophyseal trunk, which in turn arises from the
cavernous internal carotid artery. It is an important structure due to its vascular supply to lesions
in the region of the tentorium cerebelli, such as
vascular malformations and meningiomas. (B) The
inferolateral trunk arises along the lateral aspect of the cavernous internal carotid artery and projects
inferiorly. It usually has three or four branches and
multiple anastomoses with branches of the external carotid artery. (C) The neuromeningeal trunk
is a branch of the ascending pharyngeal artery
and consists of jugular and hypoglossal divisions.
(D) The posterior cerebral arteries most commonly arise as bifurcations of the basilar artery
Sagittal CT and MRI STIR sequences of the cervical
spine are shown in these images. What is the
injury type demonstrated?
A. Hangman fracture
B. Clay-shoveler fracture
C. Jefferson fracture
D. Flexion-distraction injury
E. Locked facets
D. Flexion-distraction injury
The fracture demonstrated is a classic case of a
severe flexion-distraction injury with a teardroptype fracture of the anteroinferior C4 vertebra as
well as distraction of the C4-C5 facets and posterior elements as can be seen on the CT images. The
STIR image shows extensive edema in the posterior
soft tissues including the interspinous ligaments,
which are disrupted. These are highly unstable
fractures associated with acute anterior cervical
cord syndrome. (A) A hangman (or more correctly
“hangee”) fracture involves both pedicles or both
partes interarticulares of C2 and is secondary to
hyperextension and distraction. (B) A clay-shoveler
fracture is a stable fracture involving a lower cervical vertebra (usually C7) and sometimes the
upper thoracic spine. The fracture is a type of hyperflexion avulsion injury. (C) A Jefferson fracture
is a burst fracture of the C1 vertebra. It is considered unstable if the combined offset of the lateral
C1 masses measures more than 7 mm or if the
atlantodental distance measures more than 3 mm.
(E) Locked facets may be a result of a flexiondistraction injury and can result in listhesis. The
C4-C5 facets in this case are mildly distracted.
What MRI features would favor a metastatic (pathological) compression fracture over a benign osteoporotic fracture?
A. Horizontal low signal intensity bands
B. Convex posterior vertebral margins
C. Areas of spared vertebral marrow
D. Retropulsion of a bone fragment
E. Enhancement of the involved vertebra
B. Convex posterior vertebral margins
Convex posterior vertebral margins are suggestive of metastatic disease. Other features that would
support this etiology are epidural or paravertebral
masses or the presence of vertebral metastases at
other levels. Metastases tend to involve the pedicle
and posterior elements more commonly, but these
sites also can show edema related to benign fractures. (A) Horizontal low signal intensity bands can be seen on both T1- and T2-weighted images and are more common in benign osteoporotic fractures.
(C) Areas of spared vertebral marrow (best seen as
high signal on noncontrast T1 images) are seen
more commonly in benign compression fractures.
(D) Retropulsion of a bone fragment is more suggestive of a benign compression fracture. (E) Both benign and pathological compression fractures can be accompanied by significant enhancement.
A man with a history of depression presents with
rapid and involuntary movements involving his
face and limbs. The clinical exam is notable for
hypotonia, hyperreflexia, and mild bradykinesia. A
noncontrast CT of the head is shown in this image.
What mutation is the likely cause of the patient’s
presentation?
A. Trinucleotide repeat expansion
B. Point mutation
C. Frameshift mutation
D. Deletion
A. Trinucleotide repeat expansion
The CT shows atrophy of the heads of the caudate nuclei bilaterally, resulting in abnormal ballooning of the frontal horns of the lateral ventricles,
which is consistent with Huntington disease, given
the patient’s clinical presentation. Huntington
disease results from trinucleotide (CAG) repeat expansion in the huntingtin gene, which is located on
chromosome 4. (B) Point mutations are modifications of a single nucleotide base and include substitutions, deletions, and insertions. (C) Frameshift
mutations result from insertions, deletions, or
duplications that alter the normal trinucleotide
reading frame. (D) Deletions indicate of loss of
genetic material and can involve individual bases or an entire gene
Gradient echo MRI sequences are particularly useful for the detection or evaluation of what process
or pathology?
A. Myelin injury
B. Purulence
C. Acute ischemia
D. Glucose metabolism
E. Blood products
E. Blood products
Gradient echo (GRE) sequences generate images
that particularly are susceptible to magnetic field
inhomogeneities such as those produced in the
presence of paramagnetic blood degradation products (e.g., hemosiderin and ferritin). The presence
of these products manifests as signal loss and can
be used to detect hemorrhage. Dynamic susceptibility contrast MRI and functional MRI are different techniques based on GRE sequences. (A) Myelin
injury is difficult to demonstrate on conventional
MRI unless there is clear disruption of the white
matter. Certain metrics based on advanced MRI
techniques such as radial diffusivity (RD) in diffusion tensor imaging (DTI) may serve as indicators
of primary myelin injury. A different technique
called magnetization transfer can provide a measure of the contribution of protons that are bound
to macromolecules (e.g., myelin) and has been employed in the evaluation of demyelinating disorders. (B) Diffusion-weighted imaging (DWI) with
apparent diffusion coefficient (ADC) maps is very
sensitive for the detection of purulence within
abscesses, cavities, or the ventricular system.
(C) Acute ischemia is best demonstrated with DWI
and ADC maps. (D) Glucose metabolism can be
assessed with positron emission tomography (PET)
by using fluorodeoxyglucose (FDG).
A man without a history of trauma is brought to
the emergency department with nausea, vomiting,
and ataxia. Axial T2-weighted images of the neck
and posterior fossa are shown here. What is a characteristic of the lesion in the neck?
A. It may be related to connective tissue disorders.
B. The majority occur in patients older than 60
years of age.
C. Intradural lesions are more common.
D. Rupture is more common in extradural than
intradural lesions
A. It may be related to connective tissue disorders.
The image on the left shows somewhat crescentic and nearly circumferential mural thickening of
the left vertebral artery in a patient with a spontaneous dissection (compare with the normal dark
vascular flow void on the right). The image on the
right shows cerebellar infarcts. Minor or sometimes unrecalled trauma may account for some
cases of “spontaneous” dissection, and there is an
increased incidence in patients with connective
tissue disorders. (B) Vertebral artery dissection
occurs in young and middle age adults with a mean
age of presentation of 40 years of age. (C) Extradural vertebral artery dissections are more common than intradural ones. (D) Rupture is more
common in intradural vertebral dissections because
of a lack of external elastic lamina, fewer elastic
fibers in the media, and a thinner adventitial layer.
A 56-year-old patient involved in a motor vehicle
collision underwent a cervical spine CT scan, shown
in these images. What is true of the osseous abnormality demonstrated?
A. It is consistent with an acute type 2 odontoid
fracture.
B. It results from failure of fusion of the ossiculum terminale.
C. It is associated with Morquio syndrome and
multiple epiphyseal dysplasia.
D. Orthotopic lesions are more likely to be unstable than dystopic lesions.
C. It is associated with Morquio syndrome and
multiple epiphyseal dysplasia.
An os odontoideum is a rare anomaly of the
cervical spine characterized by a deformity of the
odontoid process that appears as a smooth and
well-corticated ossicle separated from the body
of C2. There may be hypertrophy of the anterior
C1 arch, as seen in this case. It may be orthotopic
where the ossicle is in a relatively anatomic location with a gap between it and the body of C2, or
dystopic where the ossicle is located in any other
position. An increased frequency of os odontoideum has been reported in patients with multiple
epiphyseal dysplasia and in Morquio, Down, and
Klippel-Feil syndromes. (A) The ossicle above the
body of C2 is round and features smooth, wellcorticated margins; therefore, the abnormality
shown is not an acute fracture. (B) Failure of fusion
of the ossiculum terminale usually results in a much
smaller ossicle above an overall normal-appearing
odontoid process (except for a small notch at the
tip). The ossiculum terminale normally fuses with
the body of the dens around age 12. When persistent, it usually is asymptomatic and rarely associated with instability. (D) An os odontoideum usually
is asymptomatic and, in many instances, is discovered incidentally; however, it may be associated
with instability due to hypermobility of C1 over
C2. This immobility may lead to spinal cord or, less
frequently, vertebral artery compression. Dystopic
lesions are more likely to be unstable than orthotopic lesions.
A 52-year-old obese woman with a history of headaches presents to clinic. An MRI of the brain was
obtained, and is shown in these images. What additional radiographic finding may be seen?
A. Dural venous sinus stenosis
B. Venous sinus engorgement
C. Brainstem sagging
D. Decreased mammillopontine distance
A. Dural venous sinus stenosis
The axial T2 image shows distention of the optic
nerve sheaths and prominence of the optic cups bilaterally due to an increased intracranial pressure and papilledema in a patient with idiopathic
intracranial hypertension (pseudotumor cerebri).
The sagittal CISS image on the right shows an
expanded and partially empty sella turcica. Additional findings in these patients include dural
venous sinus stenosis, enlargement of the Meckel
caves, and cerebrospinal fluid arachnoid pits in
the sphenoid bones. (B) Venous sinus engorgement is seen in intracranial hypotension, not hypertension, due to decreased cerebrospinal fluid volumes (and in keeping with the Monro-Kellie doctrine). (C) Brainstem sagging is a feature of intracranial hypotension. (D) Decreased mammillopontine distance is a sign of brainstem sagging in
intracranial hypotension.
A woman who was involved in a motor vehicle collision underwent a CT of the cervical spine, which
shows a fracture involving an occipital condyle.
What structure is likely to be affected?
A. Cranial nerve IX
B. Cranial nerve X
C. Cranial nerve XI
D. Cranial nerve XII
D. Cranial nerve XII
The hypoglossal canals course along the medial
and superior aspects of each occipital condyle between the basiocciput and the jugular process.
They transmit cranial nerve XII, which is at high
risk of injury in the presence of condylar fractures.
(A) Cranial nerve IX courses through the pars nervosa of the jugular foramen along with the inferior
petrosal sinus. (B, C) Cranial nerves X and XI course
through the pars vascularis of the jugular foramen
along with the jugular bulb.
The lesion shown in this image is associated with a
chromosome 13q deletion. What is a characteristic
of this lesion?
A. Has a tendency for leptomeningeal spread
B. Anterior eye segment enhancement indicates
disease infiltration
C. Likely has high apparent diffusion coefficient
values
D. Likely has high signal intensity on susceptibility-weighted imaging
A. Has a tendency for leptomeningeal spread
The axial T2 image shows a T2 hypointense mass
involving the left posterior globe and left optic
nerve extending posteriorly to the level of the chiasm. There are foci with even lower signal intensities within the globe consistent with hemorrhage.
Although an optic glioma may cause enlargement
of the optic nerve, involvement of the eye and
deletion of chromosome 13q (which contains the
RB1 gene locus) indicates a diagnosis of retinoblastoma. This is a highly malignant tumor that has a
tendency for leptomeningeal spread. (B) Anterior
eye segment enhancement generally represents
reactive angiogenesis. (C) Retinoblastomas, as with
other primitive neuroectodermal tumors, commonly
have profoundly low apparent diffusion coefficient
values due to high cellularity and restricted diffusion. (D) The lesion shown likely has areas of low
signal intensity on susceptibility-weighted imaging
due to calcifications and hemorrhage.
What is true regarding the lesion shown in this CT
image?
A. Usually heals well with traction and immobilization
B. Usually considered stable
C. Constitutes the most common type of fracture
at this site
D. Fracture occurs above the transverse band of
the cruciform ligament
E. Most likely fracture type to progress to
nonunion
A. Usually heals well with traction and immobilization
This is a type 3 fracture of the odontoid process
extending from its base into the body of C2. These
fractures are unstable, as they allow the odontoid
process to move with the occiput as a unit; however, they have the best prognosis of all odontoid
fracture types. They usually heal well with traction
followed by bracing. (B) Although type 3 odontoid fractures have the best prognosis of all odontoid fracture types, they are considered unstable.
(C) Type 2 odontoid process fractures are the most
common. They occur across the base of the odontoid process at its junction with the body of C2.
(D) Type 3 odontoid fractures occur inferior to the
level of the transverse band of the cruciform ligament. (E) Type 2 odontoid process fractures are the
most likely to progress to nonunion.
A patient with left-sided cranial neuropathies
underwent a brain MRI study, shown in these
images. What is a likely complication of this
lesion?
A. Malignant transformation
B. Carotid-cavernous fistula
C. Subarachnoid hemorrhage
D. Posterior circulation infarcts
B. Carotid-cavernous fistula
The axial precontrast T1 image on the left shows
a round, mixed signal intensity lesion in the left
cavernous sinus. Note a subtle horizontal band at
the level of the lesion propagating in the phaseencoding direction compatible with pulsation
artifact. The T2 image on the right shows areas of
profound hypointensity. Findings are indicative of
an aneurysm, which probably is partially thrombosed. Compared with anterior and posterior circulation aneurysms, cavernous carotid aneurysms
have the lowest rate of rupture (posterior circulation aneurysms have the highest). Rupture of
cavernous carotid aneurysms may result in direct
carotid-cavernous fistulae. (A) Malignant transformation may be seen in certain neoplasms. The
lesion in this case is an aneurysm. (C) Subarachnoid hemorrhage can occur from rupture of an
intradural aneurysm. (D) Posterior circulation
infarcts can be the result of embolic phenomena
from aneurysms located more proximally in the
posterior circulation.
What is a characteristic of the entity depicted on
the digital subtraction angiographic images shown
here?
A. Cortical venous reflux denotes increased bleeding risk.
B. Multiple lesions may be seen in KlippelTrenaunay-Weber syndrome.
C. Deep venous drainage connotes increased surgical risk.
D. Most have a primarily dural vascular supply
C. Deep venous drainage connotes increased surgical risk.
With arteriovenous malformations, deep venous
drainage, involvement of eloquent cortex, and larger
nidal sizes connote an increased surgical risk and
are part of the Spetzler-Martin grading system.
(A) Cortical venous reflux is associated with an
increased bleeding risk in patients with dural arteriovenous fistulas. The patient in this case has a
pial arteriovenous malformation with a large nidus
supplied from branches of the anterior and middle
cerebral arteries. (B) Most arteriovenous malformations (98%) are solitary, but they rarely may
be multiple particularly in patients with certain
syndromes such as Osler-Weber-Rendu (who also
can have microaneurysms), Wyburn-Mason, and
craniofacial arteriovenous metameric syndromes
(CAMS). Klippel-Trenaunay-Weber syndrome is
characterized by capillary, venous, and lymphatic
malformations as well as soft tissue and osseous
hypertrophy. (D) Most arteriovenous malformations
(75%) have a primary pial blood supply from the internal carotid artery; 15% have dual supply from the external carotid artery; 10% receive blood from both the internal and external carotid arteries.
What is a characteristic of the injury shown on this
CT scan?
A. Combined offset of the lateral C1 masses relative to C2 greater than 6 mm, which suggests
disruption of the alar ligaments
B. Frequently associated with diving head first into shallow water
C. High frequency of neurologic injury
D. Most commonly occurs in infants and young
children
E. Usually warrants emergent surgical fixation
B. Frequently associated with diving head first into shallow water
This is a burst fracture of C1 (also known as Jefferson fracture) that develops due to axial loading
transmitted through the occipital condyles into
the C1 vertebra and is seen frequently after diving
head first into shallow water. Jefferson fractures
tend to be stable, and neurologic deficits are infrequent unless there is disruption of the transverse
ligament, fractures at other levels, or injury to the
vertebral arteries. Disruption of the transverse ligament is suspected if there is widening of the
atlantodens interval (normally less than 3 mm in
adults and 5 mm in children) or if the combined
offset of the lateral masses of C1 relative to the lateral C2 pillars measures greater than 6 mm. If the
transverse ligament is disrupted, stability depends
on the alar ligaments connecting the dens with the
medial aspect of the occipital condyles. (A) Combined offset of the lateral C1 masses relative to
C2 greater than 6 mm suggests disruption of the transverse ligament and raises concern about an unstable fracture. (C) Jefferson fractures have a low frequency of neurologic injury unless there is disruption of the transverse ligament, fractures at other levels, or injury to the vertebral arteries.
(D) Jefferson fractures are extremely rare in infants
and young children, probably due to the plasticity
of their bones and the presence of soft synchondroses. (E) These fractures usually are managed conservatively unless they are unstable.
The abnormality in the left frontal lobe on the CT
of the head shown in this image is consistent with
what process?
A. Acute infarction
B. Cortical contusion
C. Remote injury
D. Neoplasm
E. Abscess
C. Remote injury
The area of hypoattenuation in the left frontal
lobe is consistent with encephalomalacia. It demonstrates very low attenuation and is associated
with volume loss, as can be seen by ex vacuo expansion of the frontal horn of the left lateral ventricle. This likely is secondary to remote trauma,
infarction, or other injury. This patient also has an
acute, right frontal, extra-axial hematoma. (A, B)
Acute or subacute infarction or cortical contusion
would not be associated with volume loss, and the
lesion margins would likely be less well defined.
(D) A neoplasm would show some degree of mass
effect and may have surrounding edema. (E) There
is no fluid collection or evidence of vasogenic
edema to suggest an abscess.
What entity is compatible with the abnormality
indicated by the arrow on the MRI shown in this
image?
A. Ependymoma
B. Neuromyelitis optica
C. Subacute combined degeneration
D. Infectious myelitis
C. Subacute combined degeneration
Subacute combined degeneration is caused by
vitamin B12 deficiency, and leads to demyelination
and vacuolization of the dorsal columns of the spinal cord with or without involvement of the lateral
columns. It most commonly occurs in the upper
thoracic and cervical cord. MRI shows T2 signal
hyperintensity with rare contrast enhancement.
Subacute combined degeneration can be exacerbated or caused by nitrous oxide toxicity, which
temporarily interrupts metabolism of B12. (A) There
is no evidence of a space-occupying lesion to suggest a neoplasm. Ependymomas tend to occur centrally within the spinal cord, and cysts, hemorrhage,
and calcifications are common findings. (B) Neuromyelitis optica results in greater cord expansion
than demonstrated in the image and usually is
more central and not confined to the dorsal columns. (D) Infectious myelitis is rare, and imaging
may show edema that is not confined to the dorsal columns.
A patient with extensive T2 hyperintensity and
enhancement of the skull base shows a “black turbinate” sign on postcontrast T1 MRI sequences.
What is the likely etiology of these findings?
A. Bacterial infection
B. Invasive fungal infection
C. Nasopharyngeal carcinoma
D. Osseous infarction
B. Invasive fungal infection
The “black turbinate” sign refers to nonenhancing nasal mucosa due to tissue infarction, and has
been described in angioinvasive fungal infections. The skull base findings in this case are secondary
to fungal osteomyelitis. (A) Bacterial infection can
lead to osteomyelitis of the skull base but does not
result in a “black turbinate” sign. (C) Nasopharyngeal carcinoma can invade the skull base but does
not produce a “black turbinate” sign. (D) Osseous
infarctions can present with mixed signal intensities on T2-weighted MRI sequences due to areas of
edema and sclerosis and irregular enhancement.
Skull base infarcts are rare but occur more commonly in patients with sickle cell disease, in which case they can be complicated by osteomyelitis.
What explains the development of the abnormality demonstrated on the brain MRI shown in these
images?
A. Failure of closure of the rostral neuropore
B. Failure of diverticulation
C. Nondisjunction of the neural ectoderm
D. Premature disjunction of the neural ectoderm
B. Failure of diverticulation
These images show nonseparation of the frontal
lobes and an azygous anterior cerebral artery in a
patient with lobar holoprosencephaly. These occur
secondary to the failure of diverticulation and
cleavage of the prosencephalon during embryonic
life. Holoprosencephaly represents a spectrum of
abnormalities, with the alobar form being the most
severe and commonly presenting with a monoventricle, thalamic fusion, and facial anomalies.
(A) Failure of closure of the rostral neuropore leads
to anencephaly. (C) Nondisjunction of the neural tube can result in open spinal dysraphisms. (D) Premature disjunction of the neural tube can lead to lipomyeloceles, lipomeningoceles, and lipomyelomeningocele
What tumor type would be expected to show the
lowest apparent diffusion coefficient (ADC) values
on an MRI of the brain?
A. Atypical teratoid rhabdoid tumor
B. Juvenile pilocytic astrocytoma
C. Ependymoma
D. Dysembryoplastic neuroepithelial tumor
E. Diffuse astrocytoma
A. Atypical teratoid rhabdoid tumor
Atypical teratoid rhabdoid tumors and other
embryonal tumors as well as medulloblastomas
are highly malignant and typically show the lowest
apparent diffusion coefficient (ADC) values due to
their high cellularity. (B) Juvenile pilocytic astrocytomas are WHO grade I tumors that do not show
significant restricted diffusion. (C) Ependymomas
may show variable degrees of restricted diffusion,
but their ADC values typically are higher than those
of embryonal tumors. (D) Dysembryoplastic neuroepithelial tumors are benign glioneuronal neoplasms (WHO grade I) that do not show restricted
diffusion; therefore, their ADC values are high.
(E) Diffuse astrocytomas are WHO grade II lesions
that do not show significant restricted diffusion.
What is a characteristic of acute demyelinating
encephalomyelitis?
A. Most cases occur following vaccination.
B. Deep gray nuclei usually are spared.
C. Most lesions show contrast enhancement.
D. It is typically a monophasic process.
D. It is typically a monophasic process.
Acute demyelinating encephalomyelitis (ADEM)
usually is a monophasic process, but some patients
are at an increased risk of recurrence (defined as a
new event after 3 months) or the development of
multiple sclerosis. (A) Approximately 75% of cases
of ADEM occur after viral and less commonly bacterial (e.g., Campylobacter) infections. (B) The deep
gray nuclei (particularly the thalami) are involved
in 60% of patients with ADEM. These structures are
involved less commonly in multiple sclerosis. (C)
Only 25% of ADEM lesions show contrast enhancement. There usually is no mass effect except for
cases of tumefactive demyelination, which also may be accompanied by a leading edge of restricted diffusion.
A 5-year-old boy with visual and hearing deficits
and loss of developmental milestones presents for
evaluation. MRI of the brain shows occipitoparietal periventricular demyelination with a leading
edge of enhancement. What is the patient’s likely
diagnosis?
A. Adrenoleukodystrophy
B. Canavan disease
C. Alexander disease
D. Krabbe disease
E. Pelizaeus-Merzbacher disease
A. Adrenoleukodystrophy
The presentation and imaging findings are consistent with X-linked adrenoleukodystrophy. This
disease typically occurs in 4- to 6-year-old boys and
is caused by mutations in the ABCD1 gene, leading
to accumulation of very long chain fatty acids.
Death or progression to a vegetative state usually
occurs 2 years after symptom onset. (B) Canavan
disease is caused by mutations in the ASPA gene on
chromosome 17. It results in macrocephaly, with
imaging showing sequelae of white matter demyelination and signal abnormalities in the globi pallidi and thalami. (C) Alexander disease is caused by
mutations in the GFAP gene on chromosome 17. It
is characterized by demyelination that progresses
from anterior to posterior. Patients have astrocytic Rosenthal fibers and macrocephaly. (D Krabbe
disease results from mutations in the GALC gene
on chromosome 14 and leads to the deficiency of
galactocerebroside β-galactosidase. The condition
most commonly is diagnosed between the third
and sixth months of life. Imaging shows abnormalities in the white matter, basal ganglia, cerebellum,
and corticospinal tracts. (E) Pelizaeus-Merzbacher
disease is an X-linked recessive disorder characterized by oligodendrocyte dysfunction leading to
hypomyelination. Patients usually are males and
present with nystagmus, seizures, hypotonia, and
ataxia. On MRI, there is diffuse T2 signal hyperintensity in the white matter due to hypomyelination (myelinated white matter is dark on T2 and bright on T1 sequences).
The spinal cord lesion in the T2-weighted MRI
shown in this image is consistent with what disease process?
A. Poliomyelitis
B. Amyotrophic lateral sclerosis
C. Guillain-Barré syndrome
D. Subacute combined degeneration
D. Subacute combined degeneration
Subacute combined degeneration can be caused
by vitamin B12, copper, or vitamin E deficiencies.
It results in an abnormal signal within the dorsal
columns of the spinal cord in an inverse V-shaped
configuration with variable involvement of the lateral columns. Abuse of nitrous oxide can produce
the same syndrome through inactivation of vitamin B12. Neurosyphilis (tabes dorsalis) is also
known to involve the dorsal columns. (A) Poliomyelitis may show an abnormal signal and enhancement of anterior horn cells as well as ventral roots
of the cauda equina if accompanied by radiculitis.
(B) Amyotrophic lateral sclerosis preferentially
involves the anterior and lateral columns of the
spinal cord, which may show increased T2 signal.
(C) Guillain-Barré syndrome presents with preferential pial enhancement of the conus medullaris
and dorsal roots of the cauda equina. It should
not be associated with intramedullary signal
abnormalities.
A brain MRI shows a small lesion in the pons that
is slightly hyperintense on T2-weighted imaging
and shows “brush-like” enhancement and signal
dropout on gradient echo sequences. There is no
surrounding edema. This lesion is consistent with
what disease process?
A. Demyelinating plaque
B. Metastasis
C. Cavernous malformation
D. Capillary telangiectasia
D. Capillary telangiectasia
The imaging description of this lesion and its
location are characteristic of capillary telangiectasias. Low signal on gradient echo (GRE) sequences
is thought to be related to slow flow and increased
deoxyhemoglobin content. These lesions sometimes can have areas of gliosis, and they nearly
always are asymptomatic and found incidentally.
(A) A demyelinating plaque does not show the
constellation of features described, which are characteristic of capillary telangiectasias. (B) Capillary
telangiectasias should be differentiated from
metastases. The latter usually have surrounding
edema (except for small lesions) and do not show
signal loss on GRE sequences unless they are hemorrhagic, melanotic, or calcified. (C) Cavernous malformations may show various signal intensities
depending on the stage of their blood products.
They typically are described as having a “popcorn” or “berry” appearance with a surrounding rim of hemosiderin.
Where is a type C carotid-cavernous fistula located
according to the Barrow classification?
A. Between meningeal branches of the external carotid artery and cavernous sinus
B. Between meningeal branches of the internal carotid artery and cavernous sinus
C. Directly between the cavernous internal carotid artery and cavernous sinus
D. Between meningeal branches of both the exter- nal and internal carotid arteries and cavernous sinus
A. Between meningeal branches of the external carotid artery and cavernous sinus
Carotid cavernous fistulas can be direct or indirect. Direct fistulas (Barrow type A) develop
between the cavernous internal carotid artery and
cavernous sinus and are therefore high flow. They
are more frequent in younger males and occur secondary to trauma or rupture of a cavernous internal carotid aneurysm. Types B, C, and D occur
between meningeal branches of the internal or
external carotid arteries, are slow flow, and are
most frequently seen in women older than 50 years
of age. A type C carotid cavernous fistula occurs
between meningeal branches of the external carotid
artery and cavernous sinus. (B) A Barrow type B
fistula occurs between meningeal branches of the
internal carotid artery and cavernous sinus. (C) A Barrow type A fistula occurs directly between the cavernous internal carotid artery and cavernous sinus. (D) A Barrow type D fistula occurs between meningeal branches of both the external and internal carotid arteries and cavernous sinus.
What is a characteristic of the lesion depicted in
the MRI shown in these images?
A. Lined by arachnoid cells resulting in accumulation of cerebrospinal fluid
B. Most are intraventricular
C. Show complete signal suppression on MR
FLAIR sequences
D. Usually show areas of patchy enhancement
E. Associated with a risk of malignant transformation
E. Associated with a risk of malignant transformation
T2, FLAIR, and diffusion-weighted imaging (DWI)
MRI sequences are presented showing an epidermoid cyst. These lesions are characterized by very
bright DWI signal (presumably a combination of
restricted diffusion and T2 shine-through effect),
lack of contrast enhancement, and nonsuppression
on FLAIR. Epidermoid cysts arise from ectodermal
inclusions during neural tube closure and rarely
can degenerate into squamous cell carcinomas.
(A) Arachnoid cysts and not epidermoid cysts are
lined by arachnoid cells, resulting in accumulation
of cerebrospinal fluid. (B) Up to 50% of epidermoid
cysts are located in the cerebellopontine angle,
although they uncommonly may arise within the
ventricles. (C) Although signal in epidermoid cysts
may resemble cerebrospinal fluid on T2, they do
not suppress on FLAIR as demonstrated in the
second image. The signal of epidermoid cysts on
FLAIR sometimes has been described as “dirty”
appearing and used to be the main imaging discriminator for diagnosis before DWI was available.
This is in contradistinction to arachnoid cysts,
which do suppress on FLAIR and follow cerebrospinal fluid signal on all sequences. (D) Although
there sometimes can be minimal marginal contrast enhancement, epidermoid cysts should not
show patchy or any significant enhancement, which
would be suspicious for malignant transformation.
A 12-year-old boy presented to the emergency
department with progressive headaches, nausea,
and vomiting. Axial T2 and contrast-enhanced T1-
weighted imaging and apparent diffusion coefficient maps are shown in these images. What is the
patient’s likely diagnosis?
A. Medulloblastoma
B. Ependymoma
C. Pilocytic astrocytoma
D. Hemangioblastoma
E. Metastasis
C. Pilocytic astrocytoma
A well-circumscribed cystic mass with an avidly
enhancing mural nodule in the cerebellum most likely is a juvenile pilocytic astrocytoma in a patient of this age, which has a peak incidence between 5 and 15 years of age. Despite its classification as WHO grade I, a pilocytic astrocytoma shows avid
contrast enhancement of the solid components and paradoxically may exhibit aggressive-appearing imaging characteristics, with a metabolite pattern mimicking a high-grade lesion on MR spectroscopy (increased choline, decreased N-acetylaspartate, and increased lactate) and increased metabolism
on 18F-fluorodeoxyglucose PET studies. A pilocytic astrocytoma most commonly occurs in the cerebellum followed by the optic nerve and chiasm (particularly when syndromic in neurofibromatosis type 1) and around the third ventricle and hypothalamus. It is a slow-growing tumor and most commonly presents with manifestations of increased intracranial pressure (such as in this case where there is hydrocephalus) and cerebellar signs.
(A) Medulloblastomas usually occur in patients
younger than 5 years of age but may be seen in
older individuals. They have low apparent diffusion coefficient (ADC) values, and therefore appear dark on the ADC maps (in contrast to this case, where the solid component of the tumor is bright). Medulloblastomas arise from the superior medullary velum and fill the fourth ventricle rather than displace it. (B) Ependymomas arise from the floor of the fourth ventricle and fill it rather than displace it, in contrast to the tumor of this case. Ependymomas characteristically extrude through
the ventricular outflow tracts into the foramen
magnum and posterior fossa with a “plastic” or
“toothpaste” appearance. They also tend to be seen in younger patients with a peak incidence between 1 and 5 years of age, although there is a smaller peak in young adults later in life. Cystic changes would be an unusual finding in ependymomas. (D) Hemangioblastomas more commonly present in adults and are rare in children unless they are syndromic (peak at 40 to 60 years of age). They also can present as a cystic mass with an enhancing mural nodule that typically abuts the pial surface, and they often have prominent flow voids due to hypervascularity. They may be associated with von Hippel–Lindau syndrome, but most are sporadic. (E) Some metastases may present with cystic changes, particularly from squamous cell primaries such as in head and neck, lung, and cervical cancers. Metastases, in general, are the most common cerebellar tumor in adults. They would be unexpected in a patient of this age
A 74-year-old woman presents to the emergency
room complaining of vertigo and nausea increasing in severity over the past several hours. CT and
MRI studies were performed, and representative
images are shown here. This lesion likely represents a(n):
A. Primary neoplasm
B. Acute infarction
C. Metastatic disease
D. Arachnoid cyst
E. Epidermoid cyst
B. Acute infarction
Noncontrast CT and diffusion-weighted images
are presented, and the distribution of the abnormality and presence of restricted diffusion are most
compatible with an acute posterior inferior cerebellar artery (PICA) territory infarct. PICA infarcts
may be associated with significant mass effect in
the posterior fossa and herniation with rapid
deterioration and death. Although they can present
with specific neurologic syndromes (such as lateral or medial medullary syndromes), symptoms
can be vague and nonspecific, and sometimes may
be confused with labyrinthitis or gastroenteritis.
(A) Hemorrhagic or high-grade primary neoplasms
may result in areas of restricted diffusion due to
blood products or high cellularity, respectively;
however, they would be expected to be more
heterogeneous and would not preserve the cerebellar architecture as in this case (note that some
of the folia still can be defined on the diffusion
image). Additionally, the vascular distribution of the
abnormality and the evolution of symptoms over
a few hours are compatible with a PICA territory infarct. (C) Approximately 50% of intracranial metastases may be solitary; however, findings in this case argue against a metastatic lesion. (D) Although the lesion presented is hypodense on CT, it is intraaxial and demonstrates restricted diffusion, both of which rule out an arachnoid cyst. (E) Epidermoid cysts can show restricted diffusion, and some can be intra-axial; however, in this case, the vascular distribution is characteristic of a PICA infarct.
A man who was found lying on the ground underwent an emergent CT of the head, shown in these
images. What is the likely diagnosis?
A. Ruptured cerebral aneurysm
B. Acute arterial infarction
C. Global anoxic injury
D. Venous thrombosis
C. Global anoxic injury
This is a case of diffuse cerebral edema/global
anoxic injury. The noncontrast head CT shows
effacement of the cerebral sulci, small ventricles,
loss of the gray matter–white matter distinction,
lack of definition of the deep gray nuclei, and effacement of the basal cisterns. (A) A ruptured intradural cerebral aneurysm would result in subarachnoid
hemorrhage. The hyperdense appearance of the
suprasellar cistern in this case often is referred to
as “pseudosubarachnoid hemorrhage” and is due
to the relative hypodensity of the swollen brain
parenchyma and cisternal effacement. (B) Acute
arterial infarction would lead to edema and mass
effect in a territorial distribution. (D) Venous thrombosis may or may not result in ischemia that sometimes can become hemorrhagic. Findings that can
be seen on CT include a hyperdense clot within
the dilated vein (cord sign), cortical/subcortical
edema (when cortical veins are involved), and deep gray matter edema (when deep draining veins are involved and often occurring bilaterally).
A young woman underwent an MRI study, shown
in these images. What tumor is she at risk of
developing?
A. Glioma
B. Meningioma
C. Ependymoma
D. Endolymphatic sac tumor
E. Subependymal giant cell tumor
A. Glioma
This is a case of neurofibromatosis type 1. The
provided images show dysplasia of the left sphenoid bone with ipsilateral proptosis as well as a
diffuse, nodular, and trans-spatial lesion involving
the left head, face, neck, and parapharyngeal tissues compatible with plexiform neurofibromata. A
central T2 dark spot may be seen within some of
these lesions (the “target sign”) and is considered
highly suggestive of neurofibromas. Approximately
15% of children with neurofibromatosis type 1
develop optic nerve gliomas, and they are also at
an increased risk of developing gliomas in other
regions of the brain. In addition, 4% of patients with
neurofibromatosis type 1 develop peripheral malignant nerve sheath tumors. (B, C) Multiple inherited
schwannomas, meningiomas, and ependymomas
(MISME syndrome) are features of neurofibromatosis type 2 and not type 1. (D) Endolymphatic sac
tumors are very rare neoplasms that can occur
sporadically and have been reported to develop in 10 to 15% of patients with von Hippel–Lindau syndrome. (E) Almost all subependymal giant cell tumors are seen in the setting of tuberous sclerosis.
What factor favors an epidural versus a subdural
empyema?
A. Restricted diffusion
B. Crescentic shape
C. Crosses sutures
D. Less common cerebral edema
E. Peripheral enhancement
D. Less common cerebral edema
Epidural empyemas are associated less frequently
with cerebral edema due to the presence of thick
intervening dura between the collection and the
brain. (A) Both epidural and subdural hematomas
show restricted diffusion. (B) Similar to subdural
hematomas, a crescentic shape is more consistent
with a subdural hematoma, whereas epidural collections characteristically have a biconvex or lenticular shape. Note that subdural empyemas and
hematomas sometimes can show a lenticular shape
particularly if they are loculated. (C) Epidural collections including empyemas and hematomas do
not cross sutures due to the firm dural attachments at these sites. (E) Both subdural and epidural
empyemas enhance peripherally
A mass, shown in this image, was discovered in a
29-year-old woman presenting with progressive
bitemporal hemianopsia and hyperprolactinemia.
Immunohistochemistry and electron microscopy
following resection demonstrated chromophobic
tumor cells and “misplaced exocytosis” with
extrusion of secretory granules. What neuroimaging feature is highly suggestive of cavernous sinus
invasion?
A. Extension beyond the lateral intercarotid line
B. Carotid encasement greater than 180 degrees
C. Obliteration of the superior venous
compartment
D. Obliteration of the inferolateral venous
compartment
A. Extension beyond the lateral intercarotid line
measured on coronal images, is highly suggestive
of cavernous sinus invasion by a pituitary adenoma with a positive predictive value of 85%.
Other findings include obliteration of the carotid
venous sulcus compartment (the space between the sphenoid bone and the ipsilateral cavernous
internal carotid artery) with a positive predictive
value of 95% and internal carotid artery encasement of ≥ 67% (about 240 degrees) with a positive predictive value of 100%. (B) Carotid encasement of ≥ 67% has been associated with the highest likelihood of ipsilateral cavernous sinus invasion. (C) Obliteration of the superior venous compartment is not significantly associated with cavernous sinus invasion. (D) Obliteration of the inferolateral venous compartment is not significantly associated with cavernous sinus invasion.
What is a characteristic of the lesion depicted in
this angiogram?
A. Fibromuscular dysplasia predisposes to an
increased risk of direct-type lesions.
B. Spontaneous intracranial hemorrhage is the
most common presentation.
C. Dural-type lesions commonly present with a
subjective bruit.
D. A majority of direct-type lesions result from
venous thrombosis.
E. Dural-type lesions most commonly present in
young males.
A. Fibromuscular dysplasia predisposes to an
increased risk of direct-type lesions.
The angiogram shows early opacification of the
cavernous sinus compatible with a carotid cavernous fistula. This is most evident on the left side,
where the ophthalmic vein also can be seen. These
lesions result from either a direct communication
between the carotid artery and cavernous sinus
(direct or high-flow fistulas; Barrow type A) or
between the cavernous sinus and dural branches
of the internal carotid artery, external carotid artery, or both (indirect, low flow, and dural fistulas;
Barrow types B, C, and D, respectively). Other than
trauma and aneurysmal rupture, conditions associated with direct carotid cavernous fistulas include
fibromuscular dysplasia, Ehlers-Danlos syndrome,
and pseudoxanthoma elasticum. (B) Spontaneous
parenchymal or subarachnoid hemorrhage can be
seen in direct fistulas, particularly when there is
retrograde cortical venous flow, and occurs in about
5% of cases. Bruits and visual manifestations are much more common. (C) Direct (not dural type) fistulas commonly present with a subjective bruit (about 85% of cases) that sometimes also may be auscultated. (D) Venous thrombosis is a known mechanism in the development of some carotid cavernous fistulas; however, by far the most common etiologies of direct fistulas are trauma and aneurysm rupture. (E) Dural fistulas most commonly present in middle-aged and elderly women. Traumatic direct fistulas are more common in young males.
The tumor depicted in the MRI shown in these
images demonstrated microcysts and mild pleomorphism on histological examination and stained
positive for glial fibrillary acidic protein, neuronspecific enolase, and neuronal cell adhesion molecule. What is true about this lesion?
A. Associated with a high recurrence rate
B. Presents most commonly in young adults
C. Frequently complicated by hemorrhage
D. Associated with TSC-1 and TSC-2 gene
mutations
E. Usually shows minimal to no contrast enhancement
E. Usually shows minimal to no contrast enhancement
Subependymomas are benign, slow-growing
neoplasms classified as WHO grade I. They typically show minimal to no contrast enhancement;
however, this is variable, as some subependymomas may enhance more prominently, particularly
those located in the fourth ventricle. They may
have microcystic changes (both on histological examination and on MRI), are well circumscribed,
are noninvasive, and may contain foci of calcification. The classic location in the fourth ventricle is
at the obex, although they can occur anywhere in
the ventricular system. (A) Subependymomas are
highly resectable neoplasms. Recurrence is rare and
usually related to incomplete excision. (B) Subependymomas present most commonly in middleaged and elderly adults, with a peak incidence in
the fifth and sixth decades of life. Symptomatic
patients may present earlier with signs of intracranial hypertension. (C) Hemorrhage may occur with
subependymomas, but it is a rare event. (D) Subependymomas are not associated with TSC-1 or
TSC-2 mutations, in contrast to the subependymal
giant cell astrocytomas of tuberous sclerosis.
What is a feature of the focal areas of signal intensity (FASI) or unidentified bright objects (UBOs) in
neurofibromatosis type 1?
A. They are most common in basal ganglia and
dentate nuclei.
B. They are premalignant lesions.
C. A small proportion show contrast enhancement.
D. The presence of mass effect is characteristic.
A. They are most common in basal ganglia and
dentate nuclei.
The focal areas of signal intensity (FASI) or
unidentified bright objects (UBOs) are thought to
represent myelin vacuolization in patients with
neurofibromatosis type 1. They are most common
in the basal ganglia, dentate nuclei, and brainstem.
(B–D) These lesions are not premalignant, and
many regress in adulthood. They do not show contrast enhancement or mass effect, the presence of which should raise concern about a glioma.
What MRI sequence specifically should be included
to evaluate a patient with suspected cerebral
abscess?
A. Susceptibility weighted
B. Diffusion weighted
C. Time of flight
D. Constructive interference in steady state (CISS)
E. FLAIR
B. Diffusion weighted
The two most important sequences in the evaluation of a cerebral abscess are contrast-enhanced
T1-weighted sequences and diffusion-weighted
imaging (DWI). An abscess usually shows a relatively smooth and homogeneous enhancing wall
that often (but not always) is thicker on the side of
the gray matter and thinner toward the ventricles
and white matter. Pus within an abscess almost
always shows prominent restricted diffusion,
which is reflected as bright signal on DWI and
corresponding dark signal on apparent diffusion
coefficient (ADC) maps. (A) Susceptibility-weighted imaging (SWI) is a gradient echo–based technique
that is exquisitely sensitive for the detection of
paramagnetic and diamagnetic substances such as
ferritin, calcium, hemosiderin, and deoxyhemoglobin. The capsule of an abscess may appear dark
on SWI or T2, presumably due to the presence of
paramagnetic free radicals within macrophages.
(C) Time of flight is an MR angiography technique
that does not routinely require the administration
of contrast material and is based on the flowrelated enhancement of spins entering an imaging
slice in one direction. (D) Constructive interference in steady state (CISS) is an MRI technique that
is based on consecutive steady-state free precession
(SSFP) sequences. It produces images that have
very high T2 signal and therefore excellent contrast between fluid and parenchyma. (E) Fluidattenuated inversion recovery (FLAIR) is a pulse
sequence that uses an inversion recovery technique to null the signal of simple fluid.
A 74-year-old man underwent a CT study of the
chest, which demonstrated the lesion shown in
these images. This lesion is compatible with what
diagnosis?
A. Metastasis
B. Paget disease
C. Hemangioma
D. Plasmacytoma
C. Hemangioma
These CT images show the characteristic imaging features of a vertebral hemangioma with vertical trabeculations on the sagittal image and a
corresponding “polka dot” appearance on the axial
image. Note the preservation of the cortex despite
the presence of the trabeculations; however, also
remember that hemangiomas can be aggressive
and may present with extraosseous soft tissue
extension and mass effect on the spinal cord or
nerves. On MRI, they usually are bright on both T1
and T2 sequences due to the presence of a fatty
stroma, although atypical (predominantly vascular) hemangiomas may be dark on T1 and simulate
metastases. Approximately 30% of hemangiomas
are multiple. (A) Metastasis would result in variable degrees of marrow replacement and osseous
destruction without the vertical trabecular pattern of a hemangioma. (B) Paget disease is associated with expansion of the bone; in the spine, the
involved vertebra often appears larger than the
ones above and below it. Paget disease also presents with cortical thickening and would not show
a uniform, vertical trabecular pattern. (D) Plasmacytomas cause osseous destruction and do not
respect the trabeculae.
A 67-year-old man with left L5 radiculopathy
underwent MRI of the lumbar spine, shown in
this image. This lesion likely represents a(n):
A. Extruded disk
B. Synovial cyst
C. Ligamentum flavum hypertrophy
D. Uncovertebral joint hypertrophy
B. Synovial cyst
The axial T2 image shows a well-circumscribed,
cystic-appearing, extradural mass, with its base
along a degenerated and hypertrophied left facet
joint, which is compatible with a synovial cyst. In
this case, the cyst impinges on the left descending
nerve roots, which explains the patient’s symptoms. The morphology of the cyst and its anatomic
relationship with a degenerated facet joint are more
important than the signal of its contents, which
may vary depending on the presence of hemorrhage or proteinaceous material. Synovial cysts can
contain gas, and their walls may show enhancement or calcification. They most commonly develop
in patients older than 60 years of age and are more
common in females; 90% occur in the lumbar
spine. (A) In this case, the open base of the lesion is
centered along the facet rather than the disk, and
the T2 bright contents also seem to communicate
with the facet joint. Additionally, the lesion has
a convex, well-circumscribed margin anteriorly.
These features make a synovial cyst the right diagnosis; however, note that disk material can separate from the parent disk and migrate virtually
anywhere within the epidural space. (C) Cysts also
can originate from the ligamenta flava; however,
the lesion in this case is centered along the facet
joint. (D) The uncovertebral joints form between
the uncus and uncinate processes of the cervical
spine between C3 and C7. There are no uncovertebral joints in the lumbar spine. Additionally, hypertrophied bone and osteophytes would look dark on
T2 and not bright as in this lesion.
What is true regarding the lesion indicated by the
arrow in the contrast-enhanced T1-weighted MRI
shown in this image?
A. It is usually angiographically occult.
B. It is composed of radially arranged medullary
veins emptying into a dilated draining vein.
C. High flow from shunting may result in flowrelated aneurysms.
D. A larger nidus is associated with an increased
surgical risk.
B. It is composed of radially arranged medullary
veins emptying into a dilated draining vein.
This image shows radially arranged medullary
veins in a “caput medusae” configuration emptying into a dilated draining vein compatible with a
developmental venous anomaly (also known as a
venous angioma). These lesions usually are benign
and constitute an incidental finding in the majority of cases, although rarely they may thrombose.
Some reports have described seizures, headaches,
and hemorrhage, but the association of venous
angiomas and these manifestations has not been
established firmly. Approximately 20 to 30% of
these lesions are associated with cavernous malformations, which may explain symptoms in at
least some cases. The majority of developmental
venous anomalies are isolated, but they also can
be multiple particularly when associated with the blue rubber bleb nevus syndrome. Blood oxygen
level dependent (BOLD) imaging sequences, such as
susceptibility-weighted imaging (SWI), are the preferred modality for their detection, as these lesions
may be missed on other sequences due to their
slow flow. (A) Developmental venous anomalies
have a characteristic appearance on angiography,
showing exclusive enhancement in the venous
phase, although sometimes a faint blush may be
evident in the late arterial phase. Angiographically
occult vascular lesions include capillary telangiectasias and cavernous malformations. (C) High flow
from shunting may result in flow-related aneurysms in arteriovenous malformations. There is no
arteriovenous shunting in developmental venous
anomalies. (D) A larger nidus is associated with
an increased surgical risk in arteriovenous malformations and upgrades these lesions in the SpetzlerMartin grading system.
A patient presents to clinic for follow-up after suffering from a nontraumatic retinal detachment. The
lesion shown in these images is found on a subsequent MRI. The patient should be screened for:
A. Lisch nodules
B. Bilateral vestibular schwannomas
C. Subependymal giant cell astrocytoma
D. Renal cell carcinoma
E. Low levels of serum ceruloplasmin
D. Renal cell carcinoma
The MRI shows a heterogeneously enhancing
destructive lesion in the left petrous bone. There
are areas of intrinsic T1 hyperintensity secondary
to hemorrhage, proteinaceous contents, or cholesterol. The appearance and location are suggestive
of an endolymphatic sac tumor, particularly in a
patient presenting with spontaneous retinal detachment, which may be seen in von Hippel–Lindau
(VHL) syndrome due to hemorrhage from retinal
capillary hemangioblastomas; 15% of patients with
VHL develop an endolymphatic sac tumor, and 40
to 70% of them ultimately develop renal cell carcinoma, the incidence of which increases with age.
(A) Lisch nodules are the most common ocular
lesions in neurofibromatosis type 1. They are not
associated with VHL syndrome. (B) Bilateral vestibular schwannomas are diagnostic of neurofibromatosis type 2. (C) Subependymal giant cell
astrocytomas occur in patients with tuberous sclerosis complex secondary to mutations in the TSC-1 or TSC-2 genes, although isolated tumors rarely
have been described. These tumors are not associated with VHL. (E) Low levels of serum ceruloplasmin result in an abnormal accumulation of copper
in Wilson disease.
What is a characteristic of the condition depicted
in the T2-weighted MRI shown in this image?
A. Lined by dysplastic white matter
B. Frequently accompanied by microcephaly and other cerebral anomalies
C. Lined by endodermal endothelium
D. May show variable signal intensities depending on its contents
E. Results from a bilateral vascular insult to the
anterior cerebral circulation in utero
B. Frequently accompanied by microcephaly and other cerebral anomalies
This is a case of “open lip” (type 2) schizencephaly, which may result from a variety of insults in utero (including infection and ischemia) that affect the germinal zone during cortical development and lead to abnormal neuronal migration.
There also has been an association with COL4A1
and COL4A2 mutations. Schizencephaly manifests
as a transmantle cleft lined by dysplastic gray
matter (not white matter) that connects the subarachnoid space with the ventricular system (pia
to ependyma). It has been associated with various
anomalies including gray matter heterotopia, polymicrogyria, absence of the septum pellucidum,
and frontal lobe dysplasia. Approximately 80% of
cases are “open lip” and the rest are “closed-lip.”
(A) Schizencephaly is lined by dysplastic gray matter and not white matter, as would be the case in
porencephalic cysts. (C) Schizencephaly is lined by
dysplastic gray matter and not endodermal endothelium, which would be the case in a neurenteric
cyst. (D) A schizencephalic cleft openly communicates with the subarachnoid and intraventricular
spaces, and therefore follows cerebrospinal fluid
signal on all sequences. Cysts with proteinaceous
(e.g., neurenteric cysts) or hemorrhagic contents
may show variable signal intensities. (E) A bilateral
vascular insult to the anterior and middle cerebral
arteries in utero would lead to hydranencephaly
and destruction of parenchyma in these territories with preservation of the posterior circulation; however, large bilateral schizencephaly with hydrocephalus may be difficult to differentiate from hydranencephaly. Some authors suspect that they may be part of a continuum.
A 12-year-old boy with progressive headaches and
lower cranial nerve palsies underwent an MRI
scan, shown in these images. Which is the likely
diagnosis?
A. Chondrosarcoma
B. Chordoma
C. Nasopharyngeal carcinoma
D. Meningioma
E. Lymphoma
B. Chordoma
Skull base chordomas most commonly present
in patients between 20 and 40 years of age, but
16% occur in patients younger than 18 years of age.
Location in the lower clivus with associated osseous erosion is typical. On MRI, they demonstrate
very bright T2 signal, presumably related to mucinous contents along with thin T2 dark fibrous
septations. They show moderate to marked enhancement often along the septations in a “honeycomb” configuration. Skull base chordomas carry a
poor prognosis, worse than that for chondrosarcomas. (A) Chondrosarcomas have imaging features
similar to those for chordomas, but they more often
occur off midline and centered at the petroclival
fissure, and may be accompanied by calcified chondroid matrix. Chondrosarcomas are unusual at this
age. (C) Nasopharyngeal carcinoma is rare at this
age; it would have a more infiltrative appearance,
and it is not as bright on T2 sequences. Additionally,
the nasopharyngeal mucosa is preserved in this
case, and the tumor is centered at the skull base,
resulting in anterior deviation of the prevertebral
muscles as seen on the axial images. (D) Meningiomas can invade bone but tend to do so more diffusely. They also are not as bright on T2 sequences
(unless there are areas of degeneration) and tend
to show more homogeneous enhancement without the honeycomb appearance of this case. They
are rare in children unless associated with a syndrome. (E) Lymphoma can arise from lymphoid
tissue in the nasopharynx and extend to the skull
base; however, the nasopharyngeal mucosa in this
case is preserved. Lymphoma also usually enhances
more avidly and homogeneously.
A man presented with dysfunction of the left cranial nerves V and VI. T1- and T2-weighted MRI and
the corresponding apparent diffusion coefficient
(ADC) map are shown in these images. What is the
patient’s likely diagnosis?
A. Cholesterol granuloma
B. Cholesteatoma
C. Trapped secretions within pneumatized
petrous cells
D. Trigeminal schwannoma
A. Cholesterol granuloma
This is a well-circumscribed, expansile lesion
centered in the left petrous apex. It does not
enhance, and it shows intrinsic T1 brightness as
well as T2 dark material within it, corresponding to
blood products. There is no restricted diffusion as
demonstrated by increased signal on the apparent
diffusion coefficient (ADC) map. Findings are
compatible with a cholesterol granuloma. These
are benign lesions related to repeated middle ear
infections. They contain cholesterol crystals, lipids,
and fluid and are prone to recurrent hemorrhage.
Cholesterol granulomas can occur anywhere in
the temporal bone where there are mucosa-lined
aerated cells, and rarely have been reported in the
paranasal sinuses. (B) Cholesteatomas can occur in
this location but show restricted diffusion (they
would be dark on ADC and bright on diffusionweighted imaging) and usually are not bright on
T1. (C) Trapped secretions within pneumatized
petrous cells sometimes can show intrinsic T1
brightness due to proteinaceous contents, but they
would not result in an expansile mass. The normal trabeculae should be preserved, although this
is difficult to visualize on MRI. (D) A trigeminal
schwannoma would show enhancement and would
follow the course of the cranial nerve sometimes
with involvement of the Meckel cave.
What is the likely mechanism that caused the
injury shown in this image?
A. Lateral bending and compression
B. Axial rotation
C. Abrupt extension
D. Axial loading
E. Flexion and distraction
E. Flexion and distraction
The sagittal CT image shows a compression fracture involving a midthoracic vertebra with a fracture line extending posteriorly across the spinous
process above. This is consistent with a Chance
fracture, which features a horizontal fracture orientation through the entire spinal column and is
a result of a flexion and distraction injury. These
fractures usually are associated with lap belts.
Neurologic injury is rare, but there is an increased
frequency of intra-abdominal injuries. Up to 25%
of Chance fractures may be purely ligamentous.
(A) Extreme lateral bending can result in a lateral
compression fracture or, potentially, a fracture of
the transverse processes. Avulsion fractures of the
transverse processes in the lumbar spine also can
occur due to abrupt contraction of the psoas muscles. (B) Axial rotation can lead to facet dislocations, particularly in the cervical spine. (C) Abrupt
extension of the neck can disrupt the anterior longitudinal ligament and result in an extension teardrop fracture, which is an unstable injury. (D) Axial
loading can lead to burst or compression fractures of the anterior column if the injury occurs during flexion.
A 37-year-old man who is an intravenous drug user
presented with headaches. An MRI of the brain was
performed, shown in these images. What is an
additional expected imaging finding?
A. Presence of lactate and amino acids on MR spectroscopy
B. Hyperintense capsule on T2 sequence
C. Increased apparent diffusion coefficient values
in the center of the lesion
D. High relative cerebral blood volume ratio in
the capsule relative to white matter
A. Presence of lactate and amino acids on MR spectroscopy
The images in this case show an intra-axial lesion
with peripheral enhancement and increased signal
on diffusion-weighted imaging (DWI). Although
apparent diffusion coefficient (ADC) maps are not
presented, the degree of brightness in the center
of the lesion on DWI is high enough that this is
expected to represent restricted diffusion and
would therefore look dark on ADC maps. These
findings essentially are diagnostic of an abscess; a
few rare cases of necrotic metastases with central
restricted diffusion have been reported. Abscesses
can show various amino acids on MR spectroscopy,
including alanine, valine, leucine, and succinate as
well as lactate and lipid peaks. Of note, necrotic primary or metastatic tumors also may show lactate
and lipid peaks. (B) The capsule of a cerebral abscess
usually is iso- to hypointense on T2-weighted
sequences. This is attributed to the presence of
collagen, blood products, or free radicals generated
by phagocytosing macrophages. (C) The necrotic
center of an abscess demonstrates significant
restricted diffusion that manifests as very bright
signal on DWI and low ADC values. (D) The capsule
of an abscess typically has lower relative cerebral blood volume (rCBV) relative to white matter. Glioblastomas, which may look similar to abscesses, have been associated with high rCBV ratios in the capsule.
A 75-year-old man underwent a CT scan of the
head. Representative images are shown here. What
is the patient’s likely diagnosis?
A. Multiple myeloma
B. β-thalassemia
C. Prostate cancer metastases
D. Paget disease
D. Paget disease
The etiology of Paget disease is not entirely certain. Its hallmark is excessive bone remodeling and
overgrowth and is defined by three stages: lytic,
mixed, and sclerotic. The spine and skull are the
most common sites of involvement followed by
the pelvis. The presence of pain or focal destructive lesions on imaging should raise concern for
sarcomatous degeneration. (A) Multiple myeloma
characteristically shows numerous lucent (lytic)
lesions throughout the calvaria that may result in
a “punched out” appearance. (B) Bone marrow
hyperplasia in β-thalassemia can lead to significant skull thickening often showing a so-called
hair-on-end appearance. It would not produce the
lucent and sclerotic pattern of this case. (C) Prostate cancer metastases typically are osteoblastic
(sclerotic) and can be diffuse; however, they do not
result in the mixed lytic/sclerotic geographic pattern of this case. Note on the provided images that,
despite the diffuse involvement of the calvaria, the
inner and outer tables are relatively preserved.
The digital subtraction angiogram shown here
depicts a(n):
A. Middle cerebral artery/anterior cerebral artery
bifurcation aneurysm
B. Posterior communicating artery aneurysm
C. Basilar tip aneurysm
D. Ophthalmic artery aneurysm
B. Posterior communicating artery aneurysm
The image shown is a lateral projection of a
digital subtraction angiogram following a carotid
artery injection. It shows a vascular outpouching
projecting posteriorly from the dorsal aspect of the
C7 (communicating or terminal) segment of the
internal carotid artery at the expected origin of
the posterior communicating artery. Aneurysms in
this location represent about 30% of all ruptured
intracranial aneurysms and may result in intraparenchymal hemorrhage, typically in the mesial
temporal lobe. Patients may present with subarachnoid hemorrhage or a third cranial nerve palsy due
to mass effect. (C) This is a carotid injection and
thus does not depict the posterior circulation and
basilar tip. (D) The ophthalmic artery arises from the C6 (ophthalmic or supraclinoid) segment of the internal carotid artery and projects anteriorly.
A 53-year-old man is status post–glioblastoma
resection and radiation therapy with concomitant
temozolomide. A brain MRI shows an increasing
enhancing lesion. What neuroimaging finding
would favor the presence of recurrent tumor over
radiation necrosis/pseudoprogression?
A. Increased apparent diffusion coefficient (ADC)
values
B. Increased relative cerebral blood volumes
C. “Cut green pepper” appearance
D. Decreased FDG uptake on PET
B. Increased relative cerebral blood volumes
Studies have shown that recurrent tumor has a
higher relative cerebral blood volume (rCBV) normalized to the contralateral white matter compared with radiation necrosis, although there is some
overlap. rCBV values greater than 2.6 have been
suggested as a cutoff for the presence of recurrent
tumor, and values lower than 0.6 suggest pseudoprogression. (A) Several studies show that recurrent tumor tends to have lower apparent diffusion
coefficient (ADC) values compared with radiation
necrosis. ADC ratios related to the contralateral
white matter appear to be more accurate than absolute ADC values. (C) A “cut green pepper,” “soap
bubble,” or “Swiss cheese” appearance has been
described in radiation necrosis, although this usually does not allow reliable discrimination between these processes. (D) Decreased FDG uptake on PET favors radiation necrosis. False negatives may occur in the presence of a large area of necrosis.
A 48-year-old woman with a history of HIV underwent a brain MRI, shown in this image. The MRI
findings are consistent with:
A. Lymphoma
B. Progressive multifocal leukoencephalopathy
C. HIV encephalopathy
D. Cerebritis
C. HIV encephalopathy
HIV encephalopathy is the most common central nervous system infection related to the HIV
virus. Although the incidence of frank dementia
has decreased substantially following the advent
of highly active antiretroviral therapy, the prevalence of mild to moderate cognitive deficits in this
population has increased and probably is at least
partially related to longer survival. Note the prominent cerebral volume loss for the patient’s age,
lack of mass effect, and symmetric confluent white
matter signal abnormalities that spare the U fibers.
(A) Lymphoma would have some degree of mass
effect and would be more focal than the image
demonstrates. Lymphoma in patients with HIV/
AIDS commonly has central necrosis, whereas
lymphoma occurring in the nonimmunocompromised population is diffusely solid and enhances
homogeneously. (B) Progressive multifocal leukoencephalopathy usually is bilateral but asymmetric. When there are subcortical signal abnormalities, they virtually always involve the U fibers; note that these are spared in this case and are seen as dark gray bands between the cortex and the bright white matter lesions. (D) Cerebritis would present with variable degrees of gray and white matter edema.
What MRI sequences are necessary for the evaluation of Hirayama disease?
A. Gradient echo sequences
B. Delayed contrast sequences
C. Diffusion-weighted sequences
D. Flexion/extension sequences
D. Flexion/extension sequences
Flexion/extension sequences are important in the
evaluation of Hirayama disease (monomelic amyotrophy), as they would demonstrate detachment and anterior displacement of the dura on neck
flexion, with resultant spinal cord compression
and myelopathy. Hirayama disease is a benign and self-limiting disease that usually occurs in patients between 15 and 25 years of age. (A) Gradient echo sequences in the spine are useful to differentiate disks from osteophytes and to demonstrate foci of hemorrhage within the cord. These sequences also are less prone to cerebrospinal fluid pulsation artifact. (B) Routine postcontrast sequences help delineate the enhancing epidural space in Hirayama disease and may facilitate identification of the dura. Delayed contrast sequences are not particularly helpful. (C) Diffusion-weighted sequences are technically difficult to acquire in the spine. They may be useful in the evaluation of acute spinal cord ischemia and spinal infection.
A 45-year-old immigrant presents with a several
month history of back pain and malaise. There is
no history of fever. An MRI was performed, shown
in this image. What is the likely diagnosis?
A. Pyogenic diskitis/osteomyelitis
B. Tuberculous spondylitis
C. Degenerative disk disease
D. Osseous metastases
B. Tuberculous spondylitis
Tuberculous spondylitis (also known as Pott
disease) originates in the end plates and typically
spreads in a subligamentous fashion to involve
the adjacent vertebrae, frequently, but not always,
sparing the intervertebral disks, as seen in this case.
The provided contrast-enhanced T1 image shows a
dark lesion (presumably fluid/pus) with peripheral
enhancement. There also is enhancement of the
adjacent vertebra above with preservation of the
intervening disk. Tuberculous spondylitis has a
higher incidence of extensive paraspinal abscess
formation compared with pyogenic infections. Its
onset tends to be insidious and gradual, which not
uncommonly leads to a delayed diagnosis. Constitutional symptoms including fever and weight loss
are seen in less than 40% of cases. (A) Pyogenic
osteomyelitis typically involves the intervertebral
disks. In children, infection is thought to start in
the disks, with secondary involvement of the adjacent vertebrae. In adults, the disease is thought
to start in the end plates, with involvement of the
disks in the majority of cases. (C) Degenerative disk
disease would be centered in the intervertebral
disk spaces and may result in secondary degenerative changes in the adjacent end plates. (D) Osseous
metastases usually enhance and tend to involve
the pedicles and posterior elements. They would
not show the cystic appearance of the larger lesion
seen in the provided image.
The presence of a “swirl” sign is described on a CT
of the head. This finding indicates:
A. Thrombosis
B. Malignant transformation
C. Acute extravasation
D. Abscess formation
C. Acute extravasation
The “swirl” sign is seen on noncontrast head CT
and is defined as areas of low attenuation within
an acute intracranial hematoma. It indicates freshly
extravasated and unclotted blood and is associated
with expansion of the hematoma and a worse
prognosis. (A) Thrombosis can present as a hyperdense clot on noncontrast head CT or a filling
defect following the intravenous administration of
contrast material. (B) Malignant transformation can
occur in various neoplasms. It is not associated
with a “swirl” sign. (D) An abscess presents as a
fluid collection with an enhancing wall and surrounding edema. MRI shows central restricted diffusion. It is not associated with a “swirl” sign.
A coronal noncontrast CT reformat of a 35-yearold woman is shown in this image. What process
is likely to be directly related to the represented
disease?
A. Cytokine release and production of mucopolysaccharides
B. Hematogenous spread of poorly differentiated
adenocarcinoma
C. IgG4-positive lymphoplasmacytic infiltration
D. Monoclonal B-cell population
A. Cytokine release and production of mucopolysaccharides
Thyroid orbitopathy can affect any extraocular
muscle, but the most typical presentation is that of
involvement of the inferior, middle, and superior
rectus muscles, which are markedly enlarged in this
case. Involvement of the lateral rectus muscle almost never occurs in isolation. The pathophysiology
is thought to be related to lymphocytic infiltration
and cytokine release, which stimulates fibroblasts
to produce mucopolysaccharides and, in turn, leads
to soft tissue edema due to a hyperosmolar shift.
(B) The most common primary tumors to metastasize to the orbit are breast, lung, prostate, and melanoma. It would be unusual for orbital metastases
to result in this symmetric appearance of extraocular muscle enlargement. (C) IgG4-related disease
of the orbit is being increasingly recognized as a
cause of “idiopathic” inflammatory pseudotumor.
It can be bilateral and involve any orbital structure,
including the extraocular muscles, lacrimal sac,
and optic nerve sheath complex. (D) Lymphoma
may present as a soft tissue mass frequently related to the lacrimal gland or conjunctiva (MALT lymphoma). Other orbital structures also may be involved.
What is an expected radiographic finding in tension pneumothorax?
A. Ipsilateral diaphragmatic elevation
B. Contralateral increased intercostal spaces
C. “Deep sulcus” sign
D. Mediastinal deviation to the contralateral side
E. Tracheal deviation to the ipsilateral side
D. Mediastinal deviation to the contralateral side
A tension pneumothorax is accompanied by
shift of the mediastinal structures to the contralateral side due to a progressive mass effect. (A) The
diaphragm typically is flattened and depressed on
the side of the tension pneumothorax. (B) The ipsilateral (not contralateral) intercostal spaces increase
secondary to increased intrathoracic volume and
pressure on the side of the tension pneumothorax. (C) The “deep sulcus” sign may be seen in pneumothoraces on supine radiographs, as air collects
basally and anteriorly rather than at the apex in an
upright projection. It does not necessarily reflect
a tension pneumothorax. (E) As with mediastinal structures, the trachea may be deviated to the contralateral side in tension pneumothorax.
A CT of the lumbar spine shows a squared vertebra
with a “picture frame” appearance. This finding is
consistent with what disease process?
A. Paget disease
B. Vertebral hemangioma
C. Lytic metastasis
D. Blastic metastasis
A. Paget disease
Paget disease is a disorder of uncertain etiology
where there is excessive bone remodeling and
overgrowth. It most commonly occurs in the spine,
skull, and pelvis. In the osteosclerotic phase, there
is cortical thickening and coarsening of the trabeculations, which often lead to expansion of the
involved bone. In the spine, the vertebrae become
squared, and a thick, sclerotic margin may be seen,
resulting in the “picture frame” sign. (B) Vertebral
hemangiomas can lead to increased vertical trabeculations that may be seen as dense dots on axial
images. (C) Lytic metastases do not cause a “picture frame” appearance. (D) Blastic metastases can
produce the “ivory vertebra” sign if they involve
the entire vertebral body. Blastic metastases can be seen in various malignancies such as prostate and breast cancer, transitional cell carcinoma, and neuroendocrine tumors
What structure is supplied by the arteries shown
in this image (arrows)?
A. Posterior limb of the internal capsule
B. Anterior limb of the internal capsule
C. Anteromedial caudate nucleus
D. External capsule
E. Thalamus
A. Posterior limb of the internal capsule
The arrows point to the anterior choroidal arteries, which originate between the posterior communicating arteries and the carotid termination.
The posterior communicating arteries can be seen
immediately medial to these on the provided image.
The anterior choroidal arteries supply the posterior
limbs of the internal capsules, lateral geniculate
nuclei, optic tracts and chiasm, hippocampi, amygdalae, and choroid plexus, among other structures.
(B) The anterior limb of the internal capsule (lower
half) is supplied by the recurrent artery of Heubner, which is a branch of the proximal anterior
cerebral artery. The upper half is supplied by the
lateral lenticulostriate arteries. (C) The anteromedial caudate nucleus as well as the anterior portion
of the lentiform nucleus are supplied by the recurrent artery of Heubner. (D) The external capsule
is supplied by the lateral lenticulostriate arteries,
which are branches of the proximal middle cerebral artery and also supply the lateral aspect of the
putamen and upper half of the internal capsule.
(E) The various vascular territories of the thalamus
all are supplied by branches of the posterior cerebral and posterior communicating arteries
A 23-year-old man is brought to the emergency
department following a high-velocity motor vehicle collision. An emergent CT of the cervical spine
is shown in this image. What is a characteristic of
this lesion?
A. Uncommon in children
B. High incidence of neurovascular injury
C. Occurs secondary to axial loading
D. May be identified by a basion-dental interval
greater than 7 mm
B. High incidence of neurovascular injury
The sagittal CT image shows too much space
between the dens and tip of the clivus (basion–
dens interval) consistent with atlanto-occipital
dissociation. This is a severe craniocervical injury
that results from sudden deceleration, with hyperflexion or hyperextension of the head, which disrupts the alar, cruciate, and apical ligaments and
tectorial membrane. The condition is fatal in the
great majority of patients secondary to a high incidence of neurovascular injury. (A) Atlanto-occipital
dissociations are two to three times as common
in children as in adults, presumably due to their
relatively large head sizes, small size of their occipital condyles, and near horizontal orientation of
the atlanto-occipital joints. (C) Other less severe
injuries such as the Jefferson fracture may occur
secondary to axial loading. (D) Atlanto-occipital
dissociation injuries may be identified by a basion–
dens interval greater than 12 mm as originally
measured on lateral cervical spine radiographs. One study suggest a lower cutoff value (8.5 mm) with CT imaging, due to the presence of magnification on plain radiography.
A 45-year-old woman with history of breast cancer
underwent an MRI study of the brain. What is a
common clinical manifestation of the process presented in these images?
A. Meningismus
B. Headache
C. Ischemia
D. Diabetes insipidus
E. Dysarthria
B. Headache
Leptomeningeal carcinomatosis occurs in about
5% of patients with metastatic cancer and portends
a poor prognosis. Half of these patients present
with headaches, which represent the most common clinical manifestation. The incidence of leptomeningeal carcinomatosis is four times higher
in autopsy studies. (A) Meningismus is present in
13% of patients with leptomeningeal metastases.
(C) Ischemia is an uncommon complication of
leptomeningeal carcinomatosis. In contrast, tuberculosis can manifest with leptomeningeal disease
that characteristically results in cerebral infarcts.
(D) Diabetes insipidus can occur in patients with
infundibular involvement but is much less common than headache. It also is more frequently seen
in leukemic patients rather than in patients with
solid tumor leptomeningeal disease. (E) Dysarthria
is an uncommon complication that occurs in 7% of
patients with leptomeningeal metastases.
Axial noncontrast CT and T2-weighted MRI are
shown in these images. What is the likely diagnosis?
A. Langerhans cell histiocytosis
B. Epidermoid
C. Abscess
D. Leptomeningeal cyst
D. Leptomeningeal cyst
The CT shows a cyst-like structure projecting
through a calvarial defect. The T2 image better demonstrates that there is encephalomalacia in area of the brain, and therefore findings are compatible with a leptomeningeal cyst. These findings
develop from fractures with associated dural tears
and herniation of the pia-arachnoid through the
dural defect, with progressive osseous erosion (also
known as a “growing” skull fracture) due to cerebrospinal fluid pulsations. (A) Langerhans cell histiocytosis is an important cause of a lytic calvarial
defect in a child. Given the underlying encephalomalacia demonstrated, findings are more likely
related to prior trauma. (B) An epidermoid can be primarily calvarial, but there is no evidence of it on the MRI shown in these images, which instead shows underlying encephalomalacia. (C) The T2 image demonstrates encephalomalacia and no evidence of an abscess or parenchymal edema.
Additionally, an abscess would not result in a calvarial defect.
A 48-year-old man underwent CT and MR studies
after presenting with left-sided ophthalmoplegia.
The lesion enhanced following the administration
of intravenous contrast material and did not show
restricted diffusion. Representative images are
shown here. What is correct regarding this entity?
A. Commonly produces a chondroid matrix
B. Consists of granulation tissue and cholesterol
crystals
C. Represents trapped secretions within the
petrous apex
D. Arises from aberrant ectoderm within petrous
apex cells
E. Commonly demonstrates low apparent diffusion coefficient values
A. Commonly produces a chondroid matrix
The CT image shows a destructive lesion involving the left petrous apex and petroclival junction,
with contrast enhancement on the MRI study. There
are small, calcific densities within it that could
represent either chondroid matrix or eroded bone.
Of the provided options, this lesion is most consistent with a chondrosarcoma, which comprises a
heterogeneous group of malignant neoplasms characterized by the production of a chondroid matrix
(sometimes seen as “rings” and “arcs” within a
lytic lesion). About 1% of chondrosarcomas occurs
at the skull base and commonly slightly off midline at synchondroses such as the petroclival and
spheno-occipital sutures. (B) Cholesterol granulomas are thought to arise secondary to repeated
episodes of hemorrhage within mucosa-lined air
cells. They consist of granulation tissue and cholesterol crystals and typically are hyperintense on
noncontrast T1-weighted images with areas of T2
hypointensity related to blood products. (C) In
trapped secretions, the air cell septations are preserved, and there would not be erosive changes or
an expansile enhancing lesion. (D) Aberrant ectoderm within petrous apex cells may result in a
cholesteatoma, which does not enhance and usually is very bright on diffusion-weighted sequences
due to a combination of restricted diffusion and
T2 shine-through effects. (E) The vast majority of
chondrosarcomas are slow-growing WHO grade I
or II neoplasms that do not show significant
restricted diffusion.
A 42-year-old man with back pain underwent an
MRI examination of the lumbar spine, shown in
this image. What is an expected imaging finding
in this patient?
A. Expansion of the L5 vertebra
B. Sclerosis of the contralateral pars interarticularis
C. Widening of the spinal canal on a midsagittal image
D. Widening of the neural foramina
C. Widening of the spinal canal on a midsagittal image
Anterior listhesis secondary to pars defects (but
not due to facet hypertrophy) often results in widening of the spinal canal on a midsagittal image.
(A) Small size or hypoplasia of the L5 vertebra may
predict the presence of bilateral pars interarticularis defects and should prompt a search for them.
(B) Sclerosis of the contralateral pars interarticularis can occur with a chronic unilateral pars interarticularis defect. This patient likely has bilateral
defects as indicated by significant listhesis of L5
over S1. (D) There may be variable degrees of neural foraminal narrowing depending on the severity of the listhesis, as can be seen on this image.
A 40-year-old woman with a history of an intracranial aneurysm was brought to the emergency
department after being found lying on the ground.
An emergent CT scan showed diffuse sulcal and
cisternal hyperdensity. Images from a CT angiogram and cerebral blood volume (CBV) perfusion
map performed 5 days later are shown here. What
complication is seen?
A. Embolic infarcts following angiography
B. Cerebritis
C. Venous thrombosis
D. Vasospasm
D. Vasospasm
The reconstruction from the CT angiogram on
the left shows marked vasospasm affecting the
left greater than right middle cerebral and posterior cerebral arteries and bilateral anterior cerebral arteries. There are accompanying regions of
decreased perfusion most evident in the left middle cerebral and bilateral anterior cerebral arteries,
where there are acute infarctions. Clinically significant vasospasm after subarachnoid hemorrhage
is seen in 30% of patients and is associated with
increased mortality. (A) Embolic infarcts are a
known complication of angiography, which likely
was done in this patient with aneurysmal subarachnoid hemorrhage, but they tend to be small
and usually are located peripherally at the gray
matter–white matter junction. (B) Vasospasm following subarachnoid hemorrhage is thought to be
related to the release of spasmogenic factors during
lysis of subarachnoid blood clots and not due to
cerebritis. (C) Venous thrombosis may result in
ischemia but is not a primary complication of subarachnoid hemorrhage and would not result in the
territorial arterial perfusion deficits seen in this
case (primarily bilateral anterior cerebral and left middle cerebral arteries).
A 14-year-old boy with a history of stroke presented
for evaluation. 3D time-of-flight and T2-weighted
sequences at the level of the circle of Willis are
shown in these images. What is a characteristic of
this disease?
A. It most commonly presents in the elderly
population.
B. It may show abnormal MRI signal in engorged pial vessels.
C. Dystonia and choreoathetosis are the most
common clinical manifestations.
D. The posterior circulation is most commonly
affected.
B. It may show abnormal MRI signal in engorged pial vessels.
The MRA (left) demonstrates extensive collateralization in the region of the proximal middle cerebral arteries due to bilateral intracranial carotid
artery stenoses in a patient with (true or idiopathic) moyamoya disease. The more distal middle
cerebral arteries and visualized anterior cerebral
arteries are abnormally narrowed in this case with
preservation of the posterior circulation. Moyamoya disease may show abnormal signal in engorged
pial vessels due to collateral flow through leptomeningeal anastomoses (the “ivy sign”). Moyamoya
syndrome or secondary moyamoya (different from
moyamoya disease) is a nonspecific radiographic
finding that can show a similar pattern of collateralization and may be seen in various entities
including sickle cell disease, neurofibromatosis
type 1, Down syndrome, and connective tissue disorders, among others. (A) Moyamoya disease has a
bimodal age distribution with peaks between 5 and
9 years of age and 35 and 39 years of age. (C) The
most common manifestations of moyamoya disease are ischemia and hemorrhage. There have
been rare reports of dystonia and choreoathetosis.
(D) Moyamoya disease much more commonly
involves the anterior circulation, although the
posterior circulation also may be affected.
A 32-year-old woman with a long-standing history of intractable epilepsy underwent a contrastenhanced MRI of the brain, shown in these images.
What is a characteristic of this lesion?
A. Classified as a WHO grade II tumor
B. Commonly associated with focal cortical dysplasia
C. Shows low signal on apparent diffusion coefficient maps
D. Most demonstrate contrast enhancement
E. Has a propensity for leptomeningeal spread
B. Commonly associated with focal cortical dysplasia
Dysembryoplastic neuroepithelial tumors
(DNETs) are tumors of children and young adults
who usually present with a long-standing history
of intractable seizures. The lesions occur most
commonly in the temporal followed by the frontal
lobes, and these areas account for over 90% of
cases. DNETs commonly are associated with focal
dysplasia in the adjacent cortex. On imaging, they
characteristically show a bubbly appearance, are
cortically based, are bright on T2, and usually do
not show contrast enhancement. Calcification is
relatively common. (A) DNETs are WHO grade I
lesions. (C) DNETs do not have restricted diffusion;
therefore, they should not show low signal on
apparent diffusion coefficient maps. (D) Only about
20% of DNETs show contrast enhancement in a nodular, heterogeneous, or ring-like fashion. (E) DNETs
are slow-growing tumors that do not have a propensity for leptomeningeal spread.
A patient status post–resection of a right vestibular schwannoma underwent a noncontrast MRI
study, shown in these images. What vessel has been
injured?
A. Superior cerebellar artery
B. Posterior inferior cerebellar artery
C. Anterior inferior cerebellar artery
D. Superior cerebellar vein
E. Inferior cerebellar vein
C. Anterior inferior cerebellar artery
There is increased FLAIR signal along with
restricted diffusion involving the anterior aspect
of the right cerebellar hemisphere and middle cerebellar peduncle compatible with acute infarction.
The abnormality follows the arterial distribution
of the anterior inferior cerebellar artery, which
also supplies the inferolateral aspect of the pons
and flocculus. (A) The superior cerebellar artery
supplies the superior cerebellum, superior vermis,
dentate nuclei, and part of the midbrain. (B) The
cerebellar parenchyma posterior to the infarcted
area is supplied by the posterior inferior cerebellar
artery (PICA) and is not involved. The PICA is the
major artery of the cerebellum and supplies its
posteroinferior portion, the inferior cerebellar vermis, and the lateral medulla. (D, E) The superior
and inferior cerebellar veins drain their respective
regions of the cerebellum and transmit blood to
the dural sinuses and deep venous vasculature. The
infarct in this case shows an arterial distribution.
An axial FLAIR image is shown here. What diagnosis is represented?
A. Rhombencephalosynapsis
B. Dandy-Walker malformation
C. Blake pouch cyst
D. Mega cisterna magna
E. Joubert syndrome
E. Joubert syndrome
Joubert syndrome is characterized by vermian
hypoplasia or aplasia and a lack of decussation of
the superior cerebellar peduncles. Thickening and
a more horizontal configuration of the superior
cerebellar peduncles leads to a “molar tooth”
appearance. Diffusion tensor imaging studies show
a lack of the expected “red dot” of pyramidal
decussation. Most cases are autosomal recessive.
(A) Rhombencephalosynapsis is characterized by
an absent vermis and midline continuation of the
dentate nuclei, cerebellar hemispheres, and superior peduncles. (B) A Dandy-Walker malformation
can result in cystic enlargement of the posterior
fossa in communication with the fourth ventricle.
It does not lead to a “molar tooth” deformity. (C) A
Blake pouch cyst develops due to the persistence
of the embryonic Blake pouch. It can exert mass
effect on the posterior fossa structures. (D) A mega
cisterna magna is an incidental finding that presents as an increased subarachnoid retrocerebellar
space in the lower posterior fossa. It may be asymmetric and mistaken for an arachnoid cyst.
A 9-year-old girl with a long-standing history of
seizures and mental retardation presented to the
emergency room with nausea, vomiting, and papilledema. Physical examination demonstrated a rash
in the malar region and thick, nodular plaques with
a leathery texture on the lower back. T2-weighted
and contrast-enhanced T1-weighted MRI of the
brain are shown in these images. What is a characteristic of the lesion depicted on the MRI scan?
A. Histologically consists of balloon cells with prominent nucleoli
B. Categorized as a WHO grade II tumor
C. Usually develops after the fourth decade of life
D. Fifty percent are associated with malignant
transformation
E. Typical bubbly appearance and attachment to
the septum pellucidum
A. Histologically consists of balloon cells with prominent nucleoli
The patient’s history and clinical examination
are compatible with tuberous sclerosis. The facial
rash represents multiple angiofibromas, which tend
to occur in the malar region. The nodular plaques
on the lower back are Shagreen patches, which
are considered highly specific for this entity. MRI
shows a mixed cystic and solid mass centered in
the left foramen of Monro (location is typical)
compatible with a subependymal giant cell astrocytoma (SEGA) in this clinical context. There is
resultant obstructive hydrocephalus, which is why
the patient presented with signs of increased intracranial pressure. Other MRI findings of tuberous
sclerosis include cortical tubers, subependymal
nodules, and various white matter lesions. Histologically, SEGAs consist of balloon cells with
prominent nucleoli, although spindle cells may be
encountered and predominate in some tumors.
Pathologically, they are indistinguishable from
subependymal nodules, and on imaging, the only
reliable differentiating feature is an increase in
tumor size over serial studies (both subependymal
nodules and SEGAs can enhance). (B) SEGAs are
categorized as WHO grade I lesions. (C) SEGAs
become symptomatic between 10 and 30 years of
age but have been reported in patients as young as
1½ years of age. It is unusually rare for a SEGA to
develop after the age of 20, and, in fact, patients
without this tumor by age 25 do not need continued surveillance, as per the International Tuberous
Sclerosis Complex Consensus recommendations.
In contrast, SEGAs diagnosed early may become
symptomatic later, and lifetime monitoring may be
required for such lesions. (D) Spontaneous malignant transformation of SEGAs has been described
but is unusually rare. (E) A bubbly appearance on
MRI and attachment to the septum pellucidum is a
description that would fit a central neurocytoma.
An axial noncontrast CT and a sagittal contrastenhanced T1-weighted MRI of the head are shown
in these images. The lesion depicted likely represents a(n):
A. Epidermoid
B. Craniopharyngioma
C. Germinoma
D. Thrombosed aneurysm
E. Pituitary adenoma
B. Craniopharyngioma
A heterogeneously enhancing suprasellar mass
with cystic components and calcifications in a
child (note that the spheno-occipital synchondrosis has not yet fused) is a craniopharyngioma until
proven otherwise. These tumors most commonly
occur in children between 5 and 14 years of age
(adamantinomatous type), with a second peak in
adults between the ages of 50 and 75 years (papillary type). They arise from remnants of the craniopharyngeal duct and are histologically benign but
locally aggressive. These tumors are almost always sellar/suprasellar, although they rarely may present as purely intrasellar or even intrasphenoid,
within the third ventricle, or in the optic apparatus
without a sellar component. They have solid, enhancing components and show calcifications on
CT in 90% of cases. (A) Epidermoid tumors are rare
in the pediatric population. Except for FLAIR and
diffusion-weighted sequences, they are homogeneous, usually have a cystic appearance, and should
not show enhancing solid components. (C) The
suprasellar region is the second most common
location for germinomas, which also tend to present in the pediatric population. Calcification is rare.
(D) Aneurysms, in general, are rare in children.
Aside from vascular enhancement of the lumen,
they do not show solid enhancing components.
They may show a calcified rim corresponding to the
aneurysm wall, but they do not demonstrate the coarse, scattered calcifications seen in this case. (E) Pituitary adenomas are rare before puberty.
They can be heterogeneous in the presence of cystic or hemorrhagic changes and may resemble craniopharyngiomas; however, calcification is rare in adenomas.
Contrast-enhanced T1 and diffusion-weighted
(b = 1,000) imaging with a corresponding apparent diffusion coefficient map are shown in these
images. What is a characteristic of the lesion
shown?
A. Ependymal rosettes may be seen.
B. It is a low-grade, capillary-rich neoplasm.
C. It is formed by sheets of small round blue cells.
D. Rosenthal fibers may be present
C. It is formed by sheets of small round blue cells.
These images show characteristic features of a
medulloblastoma as an enhancing mass in the
region of the cerebellar vermis projecting into the
fourth ventricle. The lesion demonstrates restricted
diffusion, as evidenced by increased signal on diffusion-weighted imaging (center) and corresponding low signal on the apparent diffusion coefficient
(ADC) map (right). Of the most common posterior
fossa tumors, medulloblastomas have the lowest
ADC values. They are formed by sheets of small
round blue cells with minimal cytoplasm, hyperchromatic nuclei, and are similar to pineoblastomas
and retinoblastomas. (A) Ependymal rosettes are
characteristic of ependymomas. These are “plastic” tumors that may extrude through the fourth
ventricular outflow tracts in a “toothpaste” configuration. They usually show less restricted diffusion
than medulloblastomas. (B) Hemangioblastomas
are low-grade, capillary-rich neoplasms that can
occur sporadically or in the setting of von Hippel–
Lindau syndrome. They are very vascular, enhance
avidly, and may show vascular flow voids. Two
thirds of them may present as a cyst with an enhancing nodule (typically abutting the pial surface), and the rest are entirely solid. (D) Rosenthal
fibers are characteristic of juvenile pilocytic astrocytomas. They also may be present in reactive glial
tissue surrounding vascular malformations and
slow-growing tumors. Rosenthal fibers have been
described in pleomorphic xanthoastrocytomas
and Alexander disease. The solid enhancing component of pilocytic astrocytomas usually does not demonstrate much restricted diffusion.
A 23-year-old otherwise healthy man presents with
first-onset seizures. What is a characteristic of the
lesion depicted in the MRI study shown here?
A. Can result in vasospasm after rupture
B. Does not contain dermal appendages
C. Demonstrates increased alanine on MR spectroscopy at short TE
D. Chemical meningitis is a frequent complication.
E. May degenerate into a high-grade glial tumor
A. Can result in vasospasm after rupture
T1-weighted images without intravenous contrast
(note that the choroid plexus does not enhance)
demonstrate a lesion in the left frontal lobe, which
is intrinsically bright due to fat and compatible
with a dermoid cyst. A fat–fluid level is seen (left
image), which is characteristic. There also are scattered bright subarachnoid fat droplets in the sulci
as well as intraventricular extension with fat in
the frontal horns. Dermoid cysts derive from the
intracranial inclusion of cutaneous ectoderm during
closure of the neural tube and may develop after
traumatic/iatrogenic implantation. In contrast to
epidermoid cysts, they contain dermal appendages
(sebaceous and sweat glands and hair follicles).
Rupture is a rare event, and may result in chemical
meningitis, seizures, vasospasm, and ischemia. Fistulous tracts may lead to recurrent bouts of bacterial meningitis. (B) Dermoid cysts contain dermal
appendages (absent in epidermoid cysts). (C) Dermoid cysts may show a lipid peak from 0.9 to 1.3
ppm. Meningiomas (not dermoid cysts) may show
increased alanine on MR spectroscopy at short TE
values. (D) Chemical meningitis may occur after
rupture of a dermoid cyst, which is in itself a rare
event. (E) Rarely, dermoid cysts may degenerate into squamous cell carcinomas but not into highgrade glial tumors.
The lesion depicted in the MRI shown in these
images was found incidentally and has been stable
over many years. What is a characteristic of this
lesion?
A. More common in women
B. Should suppress on FLAIR sequences
C. Generally demonstrate restricted diffusion
D. Two thirds eventually are complicated by
hydrocephalus
E. Lined by ependymal cells
A. More common in women
Pineal cysts are more common in women than
in men, by a ratio of 3:1. Most pineal cysts measure less than 1 cm but may be larger, with lesions
greater than 4 cm reported in the literature. They
typically do not enhance, but may show a thin
rim of enhancement peripherally. Very rarely, nodular areas of enhancement have been reported, in
which case pineal cysts cannot be distinguished
from pineal region tumors on the basis of imaging.
Gadolinium will diffuse slowly into pineal cysts,
and, given enough time, a pineal cyst may show
enhancement on delayed imaging. The majority
are asymptomatic, but approximately 5% can compress the cerebral aqueduct and result in hydrocephalus. Size tends to be stable in males, but
pineal cysts may grow in young females with later
regression, suggesting a hormonal role in their
development. (B) Pineal cysts usually do not suppress fully on FLAIR sequences. (C) Pineal cysts do
not show restricted diffusion. (D) The majority of
pineal cysts are asymptomatic. (E) Pineal cysts are
lined by a thin layer of glial cells, fibrous tissue, and
pineal parenchyma with or without calcifications.
A 9-month-old girl with a prior finding of ventriculomegaly on a prenatal ultrasound study underwent half Fourier acquisition single shot turbo
spin echo (HASTE) T2-weighted sequences of the
brain. What is a characteristic of the entity shown
in this image?
A. The presence of a skin-covered myelomeningocele is a requisite for its development.
B. It is not clinically significant unless peg-like
tonsils descend greater than 5 mm below the
foramen magnum.
C. Gray matter heterotopia is present in 10 to 30% of cases.
D. It may be associated with a monoventricle.
C. Gray matter heterotopia is present in 10 to 30% of cases.
The image accompanying the question shows
the typical imaging features of a Chiari type 2 malformation, with descent of the brainstem through
the foramen magnum, a small posterior fossa,
beaking of the tectum, a flattened and elongated
fourth ventricle, and a thinned/dysplastic corpus
callosum. Gray matter heterotopia is seen in 10 to
30% of cases, predominantly in a periventricular
distribution. (A) Virtually 100% of Chiari type 2
malformations are associated with “open” spinal
dysraphism (not “closed” as with a skin-covered
defect). The presence of a skin-covered myelomeningocele essentially excludes the development of
a Chiari type 2 malformation, and this is the reason why some myelomeningoceles are corrected
in utero. (B) This option refers to a Chiari type 1
malformation, which presents with inferior herniation of peg-like cerebellar tonsils and is usually not
clinically significant unless the tonsils are displaced
more than 5 mm below the foramen magnum.
(D) A “monoventricle” may be seen in holoprosencephaly depending on its severity. This is not a
feature of a Chiari type 2 malformation.
Axial T2 images of the cervical spine are shown here.
What is the likely diagnosis for this pathology?
A. Paraganglioma
B. Ependymoma
C. Meningioma
D. Peripheral nerve sheath tumor
D. Peripheral nerve sheath tumor
The pathology shown in the images accompanying the question is an extramedullary neoplasm that is partially intradural and partially extradural.
It extends to the paraspinal soft tissues through
the left neural foramen, which is expanded and
remodeled, indicating that this is a slow-growing
process. Findings are most consistent with a nerve
sheath tumor. The presence of a T2 dark center (i.e.,
the “target sign” due to a fibrocollagenous core) in
the lower image suggests a neurofibroma, although
schwannomas sometimes can show a similar appearance, depending on the relative distributions
of Antoni A and Antoni B tissues. (A) Paragangliomas are rare in the spine. They tend to occur in the
conus medullaris and filum terminale. (B) Ependymomas usually are parenchymal except for the
myxopapillary type, which occurs exclusively in
the filum terminale and sometimes involves the
conus medullaris. (C) Meningiomas in the spine
are much more common in females and more
frequently occur in the thoracic spine. They are
dural-based masses, but on occasion may extrude through a neural foramen.
A 52-year-old man with long-standing symptoms
underwent a CT of the cervical spine, shown in this
image. What is the most common clinical manifestation of the condition shown?
A. Hand ischemia
B. Hand and arm dysesthesia
C. Muscle atrophy
D. Upper extremity swelling
E. Collateral vein formation
B. Hand and arm dysesthesia
The coronal CT image shows large cervical ribs
arising from the C7 vertebrae bilaterally. They may
constitute a cause of thoracic outlet syndrome. By
far, the most common clinical manifestations of
thoracic outlet syndrome are neurogenic (about
95%), and include pain, dysesthesias, weakness, and
cold intolerance in the hands, arms, or shoulders.
Most commonly, neurogenic thoracic outlet syndrome involves the C8 and T1 cervical roots, which
may result in symptoms along the ulnar nerve
distribution. Less commonly, the upper cervical
brachial plexus roots may be affected and lead
to symptoms in the neck, upper chest, and back.
(A) Signs and symptoms of arterial compression
with or without thromboembolism, including hand
ischemia, are the least common presentations of
thoracic outlet syndrome, constituting approximately 1% of cases. (C) Muscle atrophy can be
seen in cases of severe and prolonged compression of the brachial plexus, but this is extremely
uncommon. (D) Upper extremity swelling may
be a manifestation of venous compression and/or
thrombosis; however, neurogenic symptoms are
more common manifestations of thoracic outlet
syndrome. (E) Chronic venous compression can
lead to the development of collateral veins, but
neurogenic symptoms are more common in thoracic outlet syndrome.
The lesion shown on this diffusion-weighted image
no longer was present on a follow-up MRI performed
1 month later. What may be associated with such
an abnormality?
A. Demyelinating plaque
B. Embolic infarct
C. Antiepileptic drug usage
D. Acute disseminated encephalomyelitis
C. Antiepileptic drug usage
Antiepileptic drug usage and sudden withdrawal
of antiepileptic drugs have been linked to transient
splenic lesions. Various infectious, inflammatory,
and autoimmune processes have been associated
with a transient splenic lesion. The etiopathogenesis is uncertain. (A) A demyelinating plaque can
occur in the corpus callosum but more commonly
is asymmetric, and follow-up imaging may show
the sequela of demyelination. (B) The corpus callosum is relatively resistant to embolic infarcts, due
to the perpendicular orientation of its penetrating arteries and a rich blood supply. It would be
unusual for an embolic infarct to occur at the
midline. (D) Acute disseminated encephalomyelitis can affect the corpus callosum but usually is
asymmetric.
A child presents for evaluation and undergoes a
CT scan of the head. A surface-rendered 3D reconstruction is shown in this image. What gene may
be altered in the patient’s disorder?
A. TSC1
B. NOTCH3
C. FGFR
D. SMARCB1
C. FGFR
There is trigonocephaly resulting from premature fusion of the metopic suture, which usually
closes at 6 to 12 months of age. This deformity
can result in ridging along the forehead, bifrontal
and bitemporal narrowing, and hypotelorism. Most
cases of trigonocephaly are sporadic, and the
majority of nonsyndromic cases may be related
to a variety of genetic and environmental factors.
Trigonocephaly may be associated with many syndromes such as Jacobsen, Saethre-Chotzen, Opitz
C, and Say-Meyer, among others. Most syndromic
cases are related to mutations in the FGFR genes,
but alterations also may be seen in chromosomes
9, 11, and 22. (A) TSC1 and TSC2 mutations are the
hallmark of tuberous sclerosis complex. (B) NOTCH3
mutations can result in cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy. (D) Mutations in the SMARCB1
gene can lead to Coffin-Siris syndrome and an
increased risk of developing rhabdoid tumors such as ATRT.
A 65-year-old man presenting with a relatively rapid
progression of left limb ataxia and intention tremors underwent an MRI examination. Axial postcontrast T1 and diffusion-weighted (b = 1,000) images
and corresponding apparent diffusion coefficient
map are shown here. What is the likely diagnosis?
A. Metastasis
B. Glioblastoma
C. Tumefactive demyelination
D. Abscess
E. Toxoplasmosis
A. Metastasis
The images accompanying the question demonstrate an intra-axial mass in the left cerebellum
with peripheral enhancement (left) and restricted
diffusion of the enhancing component as evidenced by high signal on the diffusion-weighted image
(center) and dark signal on the apparent diffusion
coefficient map (ADC, right), which also demonstrates increased surrounding signal due to edema.
Metastases constitute the most common cerebellar tumors in adults. (B) Primary cerebellar glioblastomas are rare and constitute less than 1% of
all such tumors. Solid components may show restricted diffusion. (C) Tumefactive demyelination
may present as an enhancing mass, typically with
an incomplete ring of enhancement that may show
variable degrees of restricted diffusion. (D) Abscesses show restricted diffusion in the central necrotic component, not in the enhancing peripheral
rim. (E) Cerebral toxoplasmosis is an AIDS-defining
condition, and most cases are seen in this context.
Toxoplasma lesions tend to be small (2 to 3 cm)
and commonly occur in the gray matter–white
matter junction of the supratentorial brain and
deep gray nuclei. They may show enhancement
with an eccentric nodule (the “eccentric target”
sign) or alternating rings of T2/FLAIR hypo- and
hyperintensity related to areas of necrosis, edema, and hemorrhage.
The lesion found on the contrast-enhanced MRI
shown here demonstrates a 1p36 deletion on fluorescence in situ hybridization. What is a characteristic of this lesion?
A. Originates from arachnoid meningothelial cells
B. Most common in the pediatric population
C. Associated with mutations in or inactivation
of hamartin
D. Arises from the ependymal lining of the ventricular system
E. Usually stains positive for glial fibrillary acidic
protein
A. Originates from arachnoid meningothelial cells
1p36 deletions have been found in a variety of
human cancers. In the central nervous system,
these cancers include meningiomas, oligodendrogliomas, and neuroblastomas. Of these, an avidly
enhancing intraventricular mass would be most
consistent with a meningioma, which originates
from arachnoid meningothelial cells. In meningiomas, 1p deletions are the second most common
genetic abnormality after deletions on chromosome 22, and they have been associated with an
increased risk of tumor recurrence and progression. (B) The incidence of meningiomas increases
with age. They are very rare in the pediatric population except when they are associated with
neurofibromatosis type 2, in which case they more
frequently develop at an earlier age or in patients
with a history of radiation therapy, although the
latency in such cases may be long. (C) Hamartin is
a ubiquitous protein encoded by the TSC1 gene in
the tuberous sclerosis complex, where it is associated with the development of hamartomas in various tissues. It is not related to the formation of
meningiomas. (D) Ependymomas, not meningiomas, arise from the ependymal lining of the ventricular system. (E) Except for a few isolated reports
of papillary and rhabdoid meningiomas, these
tumors do not show glial fibrillary acidic protein
staining.
A frontal view digital subtraction angiogram following a right carotid artery injection is shown in
this image. What is the likely etiology of the lesion
demonstrated?
A. Atherosclerosis
B. Immune vasculitis
C. Congenital
D. Endocarditis
D. Endocarditis
Mycotic pseudoaneurysms form after infectious
disruption of all three layers of the arterial wall and
formation of a vascular outpouching. These lesions
characteristically arise from distal branches of the
middle cerebral artery along the surface of the
brain and can develop as a complication of endocarditis and septic emboli, as was the case in this
patient. (A) The pathogenesis of intracranial aneurysms is complex and multifactorial. Atherosclerosis may play a role in the formation of at least some
fusiform aneurysms. The lesion in this case is very
peripheral, almost along the inner table of the
skull (note the faint subtraction artifact related to
the calvaria), a location that is more often seen in
mycotic pseudoaneurysms. (B) The imaging presentation of vasculitis is variable, and in many
cases the angiogram may be normal and, therefore,
does not rule out the diagnosis. The classic finding
in vasculitis is regions of segmental stenosis and dilatation resulting in a “string of beads” appearance. (C) Mycotic pseudoaneurysms are infectious in nature.
A 43-year-old man involved in a motor vehicle collision underwent an emergent CT scan of the head,
shown in this image. What is a characteristic of
this lesion?
A. Often respects cranial sutures
B. Does not cross the midline
C. Mixed density contents predict stability
D. Most commonly occurs secondary to venous
injury
E. Develops between the inner and outer layers
of the dura
A. Often respects cranial sutures
The CT image shows a hyperdense, acute epidural hematoma with mass effect on the frontal
lobe and mild midline shift. Classically, epidural
hematomas are limited by tight dural attachments
at the cranial sutures, which results in a lentiform or biconcave shape. They usually do not cross
sutures unless there is a fracture or sutural diastasis. (B) Supratentorial subdural (not epidural)
hematomas do not cross the midline because they
are limited by the reflection of the inner layers of
the dura as they form the falx cerebri. Epidural
hematomas may cross the midline if there are no
intervening sutures or if there is a sutural fracture
or diastasis. This is seen, for instance, with vertex
epidural hematomas, which usually are venous
and associated with a fracture crossing the superior sagittal sinus and, therefore, can be seen across
the sagittal suture. (C) Mixed density contents with
areas of low attenuation within the dense hematoma (i.e., the “swirl sign”) indicate active extravasation and are an indication for emergent surgical
evacuation. (D) 90 to 95% of epidural hematomas
are due to an arterial injury. Epidural hematomas
due to a venous injury are less common and usually are associated with fractures crossing the dural
venous sinuses. (E) Epidural hematomas develop
between the outer (periosteal) layer of the dura
and the inner table of the skull.
What is a characteristic of the midbrain lesion
shown in these images?
A. Focal radiotherapy is the initial treatment of
choice.
B. The majority are low-grade lesions
C. It is the most common cause of congenital
hydrocephalus.
D. It may be related to mutations in the L1CAM
gene.
B. The majority are low-grade lesions
The majority of tectal gliomas are low-grade
lesions, but high-grade histologies also may be seen.
(A) The vast majority of tectal gliomas are lowgrade, insidious lesions that can be observed for
relatively long periods of time without intervention. Shunting with an endoscopic third ventriculostomy or ventriculoperitoneal drainage generally
is an accepted initial treatment. Tumors that persistently are symptomatic may require further
treatment, such as radiotherapy and/or chemotherapy. (C) Aqueductal stenosis is the most common cause of congenital hydrocephalus and may
be secondary to congenital stenosis of the cerebral
aqueduct or a sequela of intrauterine infection.
(D) Five to seven percent of patients with aqueductal stenosis have a congenital form (X-linked
hydrocephalus) seen in males and determined by
mutations in the L1CAM gene.
Axial FLAIR images of the brain of a 43-year-old
woman are shown here. What ancillary laboratory
finding may be present?
A. Serum aquaporin-4 antibodies
B. Serum cryptococcal antigen
C. Cerebrospinal fluid anti–Borrelia burgdorferi
antibodies
D. Cerebrospinal fluid IgG and IgM oligoclonal bands
D. Cerebrospinal fluid IgG and IgM oligoclonal bands
The axial FLAIR images accompanying the question show periventricular white matter lesions in a
radial orientation, and two juxtacortical (abutting
the cortex) lesions on the left side, characteristic of
multiple sclerosis. The presence of both periventricular and juxtacortical lesions satisfies the 2010
modified MacDonald criteria for dissemination in
space. The concurrent presence of an enhancing lesion (right image) and multiple nonenhancing
lesions satisfies the criteria for dissemination in
time. Oligoclonal bands are found in the cerebrospinal fluid in 95% of patients with clinically definite multiple sclerosis. (A) Serum aquaporin-4
antibodies are highly specific (between 92% and
99%) for the diagnosis of neuromyelitis optica and
are seen in about 60% of patients. Lesions in the
brain are not entirely specific, but tend to favor
areas of high aquaporin-4 expression. White matter
lesions with cloud-like enhancement and ependymal enhancement may be seen. (B) Cryptococcal
antigen can be detected in the serum and cerebrospinal fluid of patients with cryptococcal meningoencephalitis. Cryptococcomas and gelatinous
pseudocysts preferentially develop in the basal
ganglia and medial cerebellum, and patients can
have dilated perivascular spaces. (C) Lyme disease
is caused by the spirochete Borrelia burgdorferi.
MRI findings in the brain include nonspecific white matter lesions, which sometimes may enhance, and leptomeningeal and cranial nerve enhancement
A 17-year-old boy with progressive facial swelling
underwent a noncontrast CT scan, shown in this
image. This imaging finding is consistent with:
A. Blastic metastasis
B. Paget disease
C. Fibrous dysplasia
D. Plasmacytoma
C. Fibrous dysplasia
The CT image demonstrates osseous expansion
and remodeling of the right maxilla, adjacent
zygoma, and pterygoid process with a ground-glass
appearance that is most consistent with fibrous
dysplasia. This is a benign condition that develops
as a result of abnormal osteoblastic differentiation
and leads to replacement of normal marrow with
immature osseous and fibrous elements. Fibrous
dysplasia is a disease of children, adolescents, and
young adults. It can be monostotic (80%) or polyostotic. In the head, the most common sites of
involvement are the frontal, sphenoid, and ethmoid
bones along with the maxilla. Although the majority of cases are sporadic, fibrous dysplasia can be
seen as part of McCune-Albright and Mazabraud
syndromes. On CT, the appearance is often characteristic with areas of ground-glass texture admixed
with sclerotic and sometimes cystic changes. Diagnosis on MRI may be challenging, as the appearance is more variable. (A) Blastic (sclerotic) osseous
metastases are seen with many primary malignancies including breast and prostate cancer and
neuroendocrine tumors. They do not result in the
expansile or ground-glass appearance seen in this
case. (B) Paget disease essentially can occur in any
bone and also can result in osseous expansion;
however, it is a disease of middle-aged and elderly
individuals. The ground-glass appearance of this
case and the location are typical for fibrous dysplasia. (D) A plasmacytoma would have a destructive,
lytic appearance on CT with or without a soft tissue component. It also is a condition seen in older
individuals.
A 33-year-old woman presents to the emergency
department with an abrupt-onset, recurrent “thunderclap” headache. The initial CT scan of the head
shows a small-volume, convex subarachnoid hemorrhage. Lateral view digital subtraction angiography is shown in this image. What is the patient’s
diagnosis?
A. Venous infarction
B. Reversible cerebral vasoconstriction syndrome
C. Aneurysmal rupture
D. Acute vascular occlusion
B. Reversible cerebral vasoconstriction syndrome
The patient’s clinical presentation and imaging
findings essentially are pathognomonic for reversible cerebral vasoconstriction syndrome. The angiogram was performed following an internal carotid
injection and shows segmental multifocal narrowing involving both the anterior and posterior
(through a fetal posterior cerebral artery) circulations. Initial CT and cerebrospinal fluid studies
commonly are normal, although small-volume subarachnoid hemorrhage is present in 20% of patients
with reversible cerebral vasoconstriction syndrome.
Ischemic stroke, parenchymal hemorrhage, and
areas of edema may be seen. (A) Venous infarction
may present with headaches, nausea and vomiting, and altered mental status. It is not associated
with recurrent “thunderclap” headaches. Additionally, only the arterial phase is shown on the angiogram. (C) There is no evidence of an aneurysm on
the angiogram. (D) Acute vascular occlusion is not seen on this exam.
A 42-year-old patient presents to the emergency
department with focal back pain not relieved by
rest. He underwent an MRI examination, shown in
these images. What is/are likely to be found in the
patient’s history?
A. Lung cancer
B. Intravenous drug use
C. Fall from a height
D. Anemia, hypercalcemia, and renal failure
E. Seronegative spondyloarthropathy
B. Intravenous drug use
The sagittal T2 (left) and contrast-enhanced T1
(right) MR images show the typical findings of
diskitis/osteomyelitis with fluid/edema in an intervertebral thoracic disk and formation of an epidural abscess that extends dorsally into the spinal
canal and compresses the cord. Note the extensive
end-plate destruction and bone marrow edema
in the adjacent vertebrae. Diskitis/osteomyelitis is
more common in males, and its incidence increases
with age. Risk factors include bacteremia (nosocomial or secondary to intravenous drug use), spinal
procedures, direct inoculation from trauma, and
various causes of immunosuppression including
diabetes. (A) Metastatic disease usually spares the
intervertebral disks and would not result in a fluid
collection. Additionally, the bone marrow abnormality in this case is isolated to the vertebrae
contiguous with the infected disk. (C) Fall from a
height may result in a fracture, which would not
explain the disk-centered inflammatory findings
of this case. (D) Anemia, hypercalcemia, and renal
failure are findings that would be expected with
multiple myeloma, which is characterized by multiple lytic lesions that may have a permeative pattern on CT or radiography. Multiple myeloma can
be seen as normal on MRI or may present as multiple hyperintense foci or with a variegated, micronodular pattern. (E) A seronegative (rheumatoid factor negative) spondyloarthropathy may present
as inflammatory arthritis involving the spine and
sacroiliac joints, with corner erosions in the vertebrae and ankylosis
A 61-year-old man presents to the emergency
department with 1 day of fever, seizures, and
a decreased level of consciousness. FLAIR and
diffusion-weighted images from an emergent MRI
scan are shown here. What is a characteristic of
this entity?
A. Most commonly caused by herpes simplex
virus type 2
B. Typically involves the basal ganglia
C. Associated with hemorrhagic necrosis
D. Mediated by paraneoplastic antineuronal (antiHu) nuclear antibodies
E. Characterized by diffuse neoplastic glial cell
infiltration
C. Associated with hemorrhagic necrosis
Hemorrhagic necrosis is the pathological hallmark of HSV-1 encephalitis affecting primarily
the limbic system and temporal lobes. The classic
lesion distribution includes the mesial temporal
lobes, insular cortices, and inferior frontal lobes.
The abnormalities usually are bilateral but asymmetric, and MRI diffusion-weighted imaging and
FLAIR sequences are the most sensitive to define
their extension. Contrast enhancement is rare in
the early stages of disease but may be present later
along the gyri or leptomeninges. Prognosis is poor,
with a high incidence of neurologic sequelae. Mortality is related directly to the time of initiation of
acyclovir after disease onset. (A) Herpes simplex
virus (HSV) encephalitis beyond the neonatal
period is caused by HSV-1 in the majority of cases.
Neonates can be infected with either HSV-1 or
HSV-2 and usually present with a more diffuse type
of encephalitis. (B) HSV-1 encephalitis typically
spares the basal ganglia, but may cause middle
cerebral artery strokes that could otherwise have a
similar appearance to the image shown. (D) The
majority of patients with paraneoplastic encephalomyelitis have antineuronal (anti-Hu) nuclear antibodies. The distribution of imaging abnormalities
in limbic encephalitis may mimic that of HSV-1
encephalitis, but the clinical picture differs, with
a more subacute progression of cognitive and
behavioral changes and sometimes seizures in the
former. (E) Diffuse infiltration of two or more lobes
with neoplastic glial cells is the definition of gliomatosis cerebri. This potentially could mimic some
of the signal abnormalities seen in HSV encephalitis but would not explain the acute presentation of
symptoms in this patient.
Occlusion of the vessel shown in this image (arrow)
may result in infarction of what territories?
A. Superior cerebellum, superior vermis, dentate
nuclei, and part of the midbrain
B. Posteroinferior cerebellum, inferior cerebellar
vermis, and lateral medulla
C. Occipital lobe, thalamus, and part of the midbrain
D. Anterior aspect of the right cerebellar hemisphere and middle cerebellar peduncle
C. Occipital lobe, thalamus, and part of the midbrain
This is a digital subtraction angiogram following
an internal carotid injection. It shows a fetal origin
of the posterior cerebral artery that supplies the
occipital lobe, thalamus, and part of the midbrain.
(A) The superior cerebellar artery supplies the
superior cerebellum, superior vermis, dentate
nuclei, and part of the midbrain. (B) The posterior
inferior cerebellar artery supplies the posteroinferior cerebellum, inferior cerebellar vermis, and
lateral medulla. (D) The anterior inferior cerebellar
artery supplies the anterior aspect of the right
cerebellar hemisphere, middle cerebellar peduncle,
inferolateral aspect of the pons, and flocculus.
A 65-year-old man patient underwent an MRI of
the brain, shown in these images. What is the patient’s likely diagnosis?
A. Aneurysm
B. Meningioma
C. Choroid plexus tumor
D. Subependymoma
A. Aneurysm
This is a well-circumscribed extra-axial lesion
with mixed signal intensities and profound
peripheral T2 hypointensity along the expected
course of the posterior inferior cerebellar artery
(PICA). Findings are most concerning for an aneurysm, which probably is partially thrombosed (note
the enhancement of a nonthrombosed lumen on
the third image). There is a small, old infarct in the
left cerebellum seen on the FLAIR image likely
related to thromboembolism. PICA aneurysms are
rare, and the great majority arises proximally.
(B) Although most meningiomas enhance homogeneously, they can calcify and sometimes present
with cystic change or, very rarely, hemorrhage,
and therefore they also may show variable signal
intensities on MRI. Eighty percent of intraventricular meningiomas arise from the atrium of the lateral ventricle, and only 5% are seen in the fourth
ventricle. (C) Eighty percent of choroid plexus
tumors are benign papillomas. They are rare in
adults, where they most commonly occur in the
fourth ventricle. Papillomas tend to enhance avidly
and diffusely and characteristically show frondlike margins with a texture that is similar to that of
the normal choroid plexus. (D) Subependymomas
are slow-growing tumors that commonly are seen
in adults. They most commonly occur in the fourth
ventricle, particularly at the obex followed by the
frontal horns of the lateral ventricles. They typically do not enhance, but enhancement may be
seen in a minority of them.
A woman underwent an MRI of the brain, shown
in these images) for evaluation of headaches. What
is the likely diagnosis?
A. Giant perivascular space
B. Dysembryoplastic neuroepithelial tumor
C. Metastasis
D. Cystic glioma
A. Giant perivascular space
This lesion is formed by a cluster of cystic spaces
that follow cerebrospinal fluid signal and fully suppress on FLAIR sequences. There is a small FLAIR
hyperintense focus in the intervening parenchyma,
consistent with gliosis, but no evidence of mass
effect or any contrast enhancement. A somewhat
branching pattern is present, which may be easier
to appreciate on consecutive slices. Findings are
most consistent with a giant or tumefactive perivascular space. Although headache is the most
common complaint, its association with the presence of a giant perivascular space is uncertain.
(B) Dysembryoplastic neuroepithelial tumors can
have a bubbly appearance, and most do not
enhance. These lesions are centered in the cortex, and there usually is some identifiable mass effect.
Note that the cortex is thinned but not primarily
involved in this case. (C) Metastases almost always
have some degree of contrast enhancement. A
lesion of this size also should have considerable
surrounding edema. (D) A cystic glioma would be
associated with enhancing components or with
nonenhancing infiltrative tumor, none of which
are evident in this case.
A 9-year-old girl with a history of uncontrollable
laughing spells underwent an MRI scan and was
found to have the lesion depicted in this image
that was isointense to the cerebral cortex on
T1-weighted images (not shown). What is an
additional expected diagnostic feature of this
entity?
A. Precocious puberty
B. Moderate contrast enhancement
C. Progressive growth
D. Coarse calcifications
A. Precocious puberty
A nonenhancing mass that is isointense to gray
matter in this location in a patient of this age is
suggestive of a hypothalamic (tuber cinereum)
hamartoma. These hamartomas are composed of
disorganized neural elements, can be sessile or pedunculated, and may be iso- to hyperintense on T2
images (as in this case), depending on the proportion of glial cells within them. These are benign
lesions that do not grow and classically are associated with central precocious puberty and uncontrollable laughing spells (gelastic seizures). The
main diagnostic consideration is a low-grade glioma. (B–D) Hypothalamic hamartomas do not
enhance or grow, and calcifications are rare.
A sagittal MRI of the brain is shown in this image.
What is the likely diagnosis?
A. Craniopharyngioma
B. Rathke cleft cyst
C. Lymphocytic hypophysitis
D. Granular cell tumor
E. Neurosarcoidosis
B. Rathke cleft cyst
Rathke cleft cysts are true cysts lined by epithelium that develop from remnants of Rathke’s
pouch between the pars intermedia and pars distalis of the pituitary gland. Because the pars intermedia is difficult to visualize on imaging, it
typically appears as a homogeneous mass separating the adenohypophysis from the neurohypophysis. It almost always is homogeneous, and its signal intensity varies depending on the presence of triglycerides, cholesterol, and protein (note intrinsic
T1 hyperintensity on this noncontrast scan). It
sometimes can occur in the suprasellar compartment and almost never is symptomatic. (A) Craniopharyngiomas are heterogeneous masses that
usually arise at the level of the infundibulum. They
show areas of enhancement, and the great majority of the adamantinomatous type (seen predominantly in children) have associated calcifications.
(C) Lymphocytic hypophysitis is a nonneoplastic
inflammatory condition that may affect any part
of the pituitary gland and infundibulum. It does
not present as a discrete mass, as seen in this case.
(D) Granular cell tumors arise from granular cell
nests in the neurohypophysis or infundibulum.
They most commonly are suprasellar and almost
never are purely intrasellar. Note the normalappearing posterior pituitary bright spot along the
posterior aspect of the cyst. (E) Neurosarcoidosis
can involve the pituitary gland and infundibulum
but would not result in a discrete, well-defined
mass with intrinsic T1 hyperintensity, as in this
case.
A high-resolution axial CT of the left temporal bone
is shown in this image. To what structure does the
arrow point?
A. Singular canal
B. Facial nerve canal
C. Vestibular aqueduct
D. Semicircular canal
D. Semicircular canal
The arrow points to the posterior limb of the
posterior semicircular canal. (A) The singular canal
transmits nerve fibers from the vestibule to the
posterior semicircular canal. It is very small and
not shown on this image. (B) The tympanic segment of the facial nerve canal can be seen more
anteriorly along the medial aspect of the epitympanum. (C) The normal vestibular aqueduct is seen
as a flat line posterior and medial to the posterior
semicircular canal.
The lesion shown in these images demonstrates
sheets of densely packed cells, hyperchromatic
nuclei, and Homer-Wright rosettes. What is a
common neuroimaging feature of this lesion?
A. Low apparent diffusion coefficient values
B. “Engulfed” calcifications
C. Low density on CT
D. Dural tail
A. Low apparent diffusion coefficient values
The lesion’s location, imaging characteristics,
and pathological description are most consistent
with a pineoblastoma. These lesions are primitive
neuroectodermal tumors that most commonly
occur in children younger than 10 years of age. Like
other highly cellular tumors with a similar histology, pineoblastomas commonly have profound
restricted diffusion due to very low apparent diffusion coefficient values. (B) “Engulfed” calcifications
characteristically are described in germinomas.
Calcifications in pineoblastomas tend to be more
peripheral (“exploded”). (C) Because of their high
cellularity, pineoblastomas usually show high
density on CT. They may be heterogeneous due
to cystic changes and necrosis. (D) A dural tail is
characteristically seen in meningiomas. It should
enhance more avidly than the tumor and taper
away from it.
A 28-year-old woman presents with acute-onset
severe headache and diplopia. Representative MR
images are shown here. What is the patient’s likely
diagnosis?
A. Pituitary apoplexy
B. Craniopharyngioma
C. Epidermoid
D. Aneurysmal rupture
A. Pituitary apoplexy
Pre- and postcontrast MR images of the pituitary
fossa accompany the question. The noncontrast
image (left; note the lack of enhancement of the
nasal mucosa) shows bright foci expanding the
pituitary gland consistent with blood products.
Pituitary apoplexy is an acute syndrome that can
present with severe headaches, diplopia (due to
mass effect on the oculomotor nerves), visual deficits (if the optic chiasm or optic nerves are compressed), and hypopituitarism. Sudden deficiency
of adrenocorticotropin/cortisol may result in lifethreatening hypotension. Hemorrhage usually
occurs into a preexisting pituitary adenoma (such
as in this case; note how the sella is mildly
expanded) and rarely into a healthy gland. (B) Craniopharyngiomas typically are seen in children
but have a bimodal age peak and also can present
in young and middle-aged adults. They tend to
develop around the infundibulum (rather than
within the pituitary gland) and have a more insidious course compared with pituitary apoplexy.
(C) Epidermoid tumors in this region usually are
suprasellar. On T1-weighted sequences, they tend
to have signal intensities close to that of cerebrospinal fluid and do not enhance. They may result in
mass effect on adjacent structures, but their presentation would be more insidious than pituitary
apoplexy. (D) Aneurysms can have unusual signal
intensities due to thrombosis and also can present
with acute headache if they rupture. The lesion in
this case arises within the pituitary gland as can
be seen by small claws of enhancing tissue around the hemorrhage.
The lesion shown here, found in a 25-year-old
woman, was hyperdense to gray matter on noncontrast CT and showed restricted diffusivity on
apparent diffusion coefficient maps. A normal
pituitary gland was identified on sagittal MRI (not
shown). Pathology demonstrated sheets of large,
polygonal primitive cells with clear, glycogen-rich
cytoplasm and abundance of lymphocytes. How
does this lesion respond to radiation?
A. The pathology is entirely radiation insensitive
and should not be treated by radiation.
B. The lesion is mostly radiation insensitive, but
radiation may be somewhat effective.
C. The lesion is mostly radiation sensitive, and
radiation typically may be effective.
D. The lesion is entirely radiation sensitive and
should be treated primarily by radiation.
D. The lesion is entirely radiation sensitive and
should be treated primarily by radiation.
The imaging and pathological characteristics of
this mass in a young adult are most consistent
with a germinoma. A normal pituitary gland is
present on the sagittal images; therefore, this is
not a pituitary adenoma. Germinomas usually
demonstrate avid homogeneous enhancement as
well as restricted diffusion on MRI apparent diffusion coefficient maps and hyperdensity on CT due
to their high cellularity. Although pineal region
germinomas are significantly more frequent in
males (male-to-female ratio of 10:1), the gender
distribution of suprasellar lesions is relatively even.
Pure germinomas are exquisitely sensitive to radiation, with long-term progression-free survival rates greater than 90% for localized lesions; therefore, this constitutes the mainstay of therapy, and
gross total resection is not usually recommended
for pure germinomas. The role of surgery in such
cases generally is limited to tissue biopsy and
decompression in cases of acute visual symptoms
(in suprasellar lesions) or obstructive hydrocephalus (in pineal lesions). Although most germinomas
do respond to chemotherapy, chemotherapy alone
is associated with high rates of relapse.
What presentation is consistent with the MRI
shown in this image?
A. Vision loss
B. Hemiparesis
C. Gait ataxia
D. Wallenberg syndrome
E. Locked-in syndrome
B. Hemiparesis
The axial FLAIR image shows increased signal in
the visualized portions of the right internal carotid
artery within the carotid canal due to thrombosis,
which may result in left hemiparesis if there is
resultant anterior circulation ischemia. (A) Vision
loss may be seen as a consequence of posterior circulation infarcts involving the visual cortex. (C) Gait
ataxia may result from occlusion of the cerebellar
arteries. (D) Lateral medullary syndrome (also
known as Wallenberg syndrome) usually results
from posterior inferior cerebellar artery territory
infarcts. (E) Locked-in syndrome may be secondary to infarcts of the lower pons in the proximal
basilar artery territory
A 5-year-old otherwise healthy girl presents with
a several-week history of neck pain. An MRI of the
cervical spine was performed, and a sagittal T2
image is shown here. What is the patient’s likely
diagnosis?
A. Metastasis
B. Eosinophilic granuloma
C. Telangiectatic osteosarcoma
D. Diskitis-osteomyelitis
E. Fracture
B. Eosinophilic granuloma
Eosinophilic granuloma is the localized form
of Langerhans cell histiocytosis characterized by
infiltration with myeloid dendritic cells. In the spine,
it most commonly affects the vertebral body and
can result in a vertebra plana with variable degrees
of epidural or paravertebral tissue. T2 signal tends
to be normal or near normal. (A) Metastases from
neuroblastoma usually are more heterogeneous
and ill defined. They also may present with a soft
tissue component projecting outside of the vertebra. (C) Telangiectatic osteosarcomas of the spine
are rare. They are heterogeneous and frequently
hemorrhagic with fluid–fluid levels. (D) Diskitisosteomyelitis is an infectious process that, in children, probably begins in the disk (which still is
vascularized). It would result in increased T2 signal
within the disk and variable degrees of end-plate
destruction (not present in this case). (E) A fracture would not have such a homogeneous appearance with smooth margins unless it is chronic. It
also would not explain the solid-appearing tissue
bulging into the prevertebral region.
What is the structure indicated by the arrow on
this lateral view digital subtraction angiogram?
A. Sphenoparietal sinus
B. Superior petrosal sinus
C. Inferior petrosal sinus
D. Inferior anastomotic vein
E. Marginal sinus
C. Inferior petrosal sinus
Shown in the image accompanying the question
is the inferior petrosal sinus, which generally transmits blood from the cavernous sinus to the jugular
vein or, less commonly, to the suboccipital venous
plexus via the hypoglossal canal; however, there is
marked anatomic variation. (A) The sphenoparietal
sinus receives tributaries from the middle cerebral, middle meningeal, and anterior diploic veins,
and drains into the cavernous sinus. It courses along
the ridge of the lesser wing of the sphenoid bone.
(B) The superior petrosal sinus runs along the
superior aspect of the petrous bone and drains blood from the cavernous sinus into the transverse
sinus. (D) The inferior anastomotic vein (of Labbé)
drains the temporal convexity and opercular region transmitting blood from the middle cerebral vein to the transverse or sigmoid sinus. (E) The marginal sinus extends along the rim of the foramen magnum
What grade is the intraventricular hemorrhage
demonstrated on the cranial ultrasound image
shown here?
A. Grade 1
B. Grade 2
C. Grade 3
D. Grade 4
E. Grade 5
D. Grade 4
The coronal ultrasound image accompanying
the question shows intraventricular hemorrhage
involving the entire right lateral ventricle and left
temporal horn. There is extensive parenchymal
abnormality surrounding the right lateral ventricle due to venous ischemia. Findings are consistent
with grade 4 intraventricular hemorrhage. Note
ventricular dilatation. (A) Grade 1 intraventricular
hemorrhage is confined to the germinal matrices,
which are located in the caudothalamic grooves.
(B) Grade 2 intraventricular hemorrhage is defined
by intraventricular hemorrhage extension with
normal-sized ventricles. (C) Grade 3 intraventricular hemorrhage is defined by intraventricular
hemorrhage extension accompanied by ventricular
distention. (E) There is no grade 5 intraventricular
hemorrhage.
Representative MR images of the brain are shown
here. What is the likely diagnosis?
A. Arachnoid cyst
B. Giant perivascular space
C. Neuroglial cyst
D. Cysticercal cyst
C. Neuroglial cyst
The axial T2 image accompanying the question shows a well-circumscribed, cystic-appearing
parenchymal lesion in the right cerebellum with an
imperceptible wall. There is no contrast enhancement. Findings are most consistent with a neuroglial cyst. These are benign, epithelial-lined lesions
of different sizes that can be found virtually anywhere in the neuraxis. There typically is no surrounding edema. (A) Arachnoid cysts are extra-axial.
This is an intra-axial lesion, as it is nearly completely surrounded by parenchyma. (B) Even though
they can occur in isolation, giant perivascular
spaces usually have some structure to them and
often show a clustered or branching pattern. It
would be very unusual for one to present as a single, well-circumscribed cyst. Giant perivascular
spaces can have areas of FLAIR hyperintensity due
to gliosis around them. (D) Cysticercal cysts usually
are smaller than the pictured cyst. A scolex, wall
enhancement, calcification, or surrounding edema
may be seen depending on the Escobar stage of
the parasite. The racemose form can develop within
the subarachnoid space or ventricles and appears
like a cluster of cysts.
A coronal T2-weighted image of the brain of a
pediatric patient is shown here. What may be seen
in the depicted disease entity?
A. Increased N-acetylaspartate on MR
spectroscopy
B. Increased FDG uptake interictally
C. Hypertrophy of the ipsilateral fornix
D. Atrophy of the ipsilateral mammillary body
D. Atrophy of the ipsilateral mammillary body
The image accompanying the question shows
atrophy and loss of the internal architecture of
the right hippocampus with increased signal.
Additionally, there is atrophy of the ipsilateral
mammillary body compared with the left, as can
be seen in severe and long-standing cases of mesial
temporal sclerosis. (A) MR spectroscopy may show
decreased N-acetylaspartate and mildly increased
myoinositol in mesial temporal sclerosis. (B) FDGPET may by useful by showing decreased metabolism/uptake in the hippocampus in patients with
mesial temporal sclerosis even in the absence of
structural abnormalities on MRI. (C) Atrophy of the
ipsilateral fornix can be seen in severe and longstanding cases of mesial temporal sclerosis.
What is a characteristic of the lesion depicted on
the CT and MR images shown here?
A. Requires a pial-arachnoid defect
B. Majority are iatrogenic
C. Lined by true epithelium
D. Lined by an arachnoid membrane
A. Requires a pial-arachnoid defect
The images accompanying the question show
an intracerebral pneumatocele. The coronal CT
reformat (left) shows a fracture through the right
frontal sinus and air tracking intracranially with
the formation of a parenchymal air cyst, which can
be characterized best on the axial T2 image (right). There also is a cerebrospinal fluid level present
within the cyst. An intracerebral pneumatocele
requires a defect in the pia-arachnoid membrane
in close proximity to a craniodural defect. Air may
accumulate due a ball valve effect or possibly due
to increased cerebrospinal fluid leakage, leading to
slightly negative intracranial pressures. (B) About
75 to 90% of intracerebral pneumatoceles are secondary to trauma as in this case. Pneumatoceles
are present in up to 25% of all cases of pneumocephalus. (C) Pneumatoceles are not true cysts, and
therefore are not lined by epithelium. (D) Arachnoid cysts are lined by arachnoid cells formed by
the splitting of arachnoid membranes.
T2-weighted MR images of the cervical spine in a
patient with history of trauma are shown here.
What is an additional imaging finding that may be
seen?
A. Contrast enhancement of the ovoid lesions
B. Signal suppression of the ovoid lesions on STIR
images
C. Enhancement of the paraspinal musculature
D. Restricted diffusion in the ovoid lesions
C. Enhancement of the paraspinal musculature
Enhancement of the paraspinal musculature is
an indirect sign of avulsion injury due to denervation. Enhancement of intradural nerve roots indicates functional avulsion even in the presence of a
normal-appearing nerve. (A) These lesions are fluid-filled pseudomeningoceles and would not show
contrast enhancement unless they were infected.
(B) Fatty lesions would show suppression of signal
on STIR images. (D) Restricted diffusion may be
seen in many disease processes. In the spinal cord,
it can be secondary to infection or cord ischemia.
The pseudomeningoceles in this case would not show restricted diffusion.
What anatomic structure is indicated by the arrow
in this image?
A. Oculomotor nerve
B. Trochlear nerve
C. Trigeminal nerve
D. Abducens nerve
E. Glossopharyngeal nerve
C. Trigeminal nerve
Shown in the image accompanying the question
is the trigeminal nerve, which arises from the
lateral aspects of the pons. It has a characteristic
shape, with fibers that appear to spread out before
piercing the dura and entering the Meckel cave.
(A) The oculomotor nerves are relatively thick and
can be identified exiting the brainstem at the level
of the pontomesencephalic junction. They course
between the posterior cerebral and superior cerebellar arteries on coronal images. (B) The trochlear
nerve generally is not seen on CISS or FIESTA images due to its small caliber, unless thinner slices
are acquired (0.4 mm). (D) The abducens nerves are
thin and can be seen exiting the brainstem at the
level of the pontomedullary junction. (E) The glossopharyngeal nerve is part of the cranial nerve
IX–X–XI complex. It exits the upper medulla and
leaves the skull through the pars nervosa of the
jugular foramen.
A 23-year-old man sustained trauma to the right
side of his neck during a motor vehicle collision.
The CT angiogram is shown here. What is the
patient’s diagnosis?
A. Vertebral artery dissection
B. Carotid artery pseudoaneurysm
C. Carotid artery dissection
D. Vertebral artery pseudoaneurysm
E. Node of Rouvière
C. Carotid artery dissection
The axial CT angiogram image shown here
demonstrates a crescentic, eccentric soft tissue
density along the lateral aspect of the right internal carotid artery (arrows) consistent with a dissection. These dissections can be traumatic, as in
this case, or associated with collagen vascular disease or iatrogenic causes. They may result in ischemic or embolic strokes and can be associated with
pseudoaneurysm formation, Horner syndrome, or
retinal ischemia. (A) There is no visible vertebral
dissection. (B) Pseudoaneurysms sometimes may
complicate a carotid artery dissection and may
occur within hours, months, or years after the
initial injury. In a pseudoaneurysm, the intima,
media, and adventitia of the arterial wall are absent.
(D) The visualized vertebral arteries are normal
in this case. (E) The node of Rouvière is the most
superior of the lateral retropharyngeal nodes. In
children, it most commonly is enlarged secondary
to infection, but it raises suspicion about malignancy of the upper aerodigestive tract in older
patients.
The lesion in the right sacrum on the noncontrast
CT study shown in this image likely represents:
A. Blastic metastasis
B. Osteoid osteoma
C. Enostosis
D. Osteoblastoma
C. Enostosis
The density of the lesion and radiating spicules
that blend with the surrounding trabeculae are
classic findings for an enostosis, commonly known
as a bone island. These are incidental benign lesions that occur in cancellous bone. (A) Blastic metastases
can be secondary to a variety of tumors. Bone
islands sometimes can be mistaken for metastases
when their characteristic imaging findings are not
present. (B) Osteoid osteomas usually present as a
lucent nidus surrounded by sclerotic bone and may
have a dense, calcified center. They more commonly occur in long bones and in the spine where
they preferentially involve the posterior elements.
(D) Osteoblastomas are benign lesions that may be
locally aggressive. They are histologically similar
to osteoid osteomas but are much larger. They are
predominantly lytic (unlike enostoses, which are
dense), but may have matrix mineralization that can be seen on CT.
What anatomic variant is shown on the time-offlight MR angiography in this image?
A. Persistent hypoglossal artery
B. Persistent trigeminal artery
C. Persistent otic artery
D. Persistent stapedial artery
E. Persistent pro-atlantal artery
B. Persistent trigeminal artery
A primitive trigeminal artery is the most common of the persistent fetal carotid-vertebrobasilar
anastomoses. It arises at the junction of the cavernous and petrous segments of the internal carotid
artery and courses along the trigeminal nerve or
over the dorsum sellae. It may be associated with
hypoplasia of the basilar artery, and a possible
increased incidence of intracranial aneurysms and
vascular malformations has also been described.
(A) A persistent hypoglossal artery is second in
frequency after a persistent trigeminal artery
(although still much less common). It originates
from the distal cervical internal carotid artery and
courses through an enlarged hypoglossal canal to
terminate in the basilar artery. (C) The primitive
otic artery is the earliest fetal artery to disappear
in embryonic life and represents the least common
of the persistent fetal carotid-vertebrobasilar anastomoses. It arises from the internal carotid artery
within the carotid canal and courses through the
internal acoustic meatus to join the basilar artery.
(D) The primitive stapedial artery is not part of the
embryonic carotid-vertebrobasilar anastomoses.
A persistent vessel may arise from the caroticotympanic or inferior tympanic arteries at the level
of the carotid canal and course along the cochlear
promontory or through or parallel to the facial
nerve canal. (E) A persistent pro-atlantal artery
arises from the internal (type 1) or external (type
2) carotid artery and communicates with a vertebral artery. It rarely may arise from the common
carotid artery.
A 50-year-old woman is brought to the hospital
with altered mental status and a vertical gaze palsy.
Diffusion-weighted MRI sequences (b = 1,000) are
shown in these images. What is the patient’s likely
diagnosis?
A. Bithalamic glioma
B. Percheron artery infarct
C. Deep venous thrombosis
D. Top of the basilar syndrome
B. Percheron artery infarct
In the MRI scans shown accompanying the question, there is restricted diffusion with very high
signal in a particular arterial territory involving
the paramedian thalami bilaterally as well as the
rostral midbrain, consistent with Percheron artery
territory infarcts. Although there is some variability, the paramedian arteries arise from the posterior cerebral arteries and supply this particular
thalamic territory (in some patients they also may
supply the anterior polar regions). The artery of
Percheron is an anatomic variant, whereby a single artery supplies both paramedian thalamic territories. There is variable blood supply to the rostral
midbrain, which may or may not be involved.
(A) Bithalamic gliomas are rare and would not be
restricted to the territory of the paramedian thalamic arteries or explain involvement of the rostral
midbrain. (C) Deep venous thrombosis can result
in diffuse swelling of the deep gray nuclei, but
would not lead to the particular arterial territorial
pattern of this case. (D) Top of the basilar syndrome occurs when a thrombus lodges at the distal
basilar artery occluding both posterior cerebral
arteries. This can result in occlusion of the paramedian thalamic arteries but likely will result in
infarction of other posterior cerebral artery territories, which do not appear involved in this case.
What is a characteristic of the lesion shown on
these pre- and postcontrast CT images?
A. It is treated primarily with open microsurgery.
B. It has a lower rate of hemorrhage compared
with anterior circulation lesions.
C. It hemorrhages primarily into the interhemispheric fissure.
D. The apex is the most common location.
D. The apex is the most common location.
The apex (tip) is the most common location of
basilar artery aneurysms, and lesions at this site
represent 50 to 80% of all posterior fossa aneurysms. Aneurysms of the basilar trunk are rare.
Other locations for basilar artery aneurysms include
the junctions of the posterior cerebral, anterior
inferior cerebellar, and superior cerebellar arteries.
(A) Endovascular therapy the is mainstay for treating basilar tip aneurysms and largely has replaced
traditional microsurgical techniques, which necessitate significant brain retraction and temporary
arterial occlusion that may result in significant
morbidity or mortality. (B) Posterior circulation
aneurysms have the highest rate of rupture of all
intracranial aneurysms. Basilar and internal carotid
artery aneurysms also may be more likely to grow
compared with aneurysms developing at other sites.
(C) The epicenter of subarachnoid hemorrhage
may suggest the site of the aneurysm. Anterior
communicating artery aneurysms bleed primarily
into the interhemispheric fissure, and those from
the middle cerebral artery hemorrhage bleed into
the sylvian fissure. Basilar tip aneurysms characteristically bleed into the basilar cisterns, posterior
third ventricle, and fourth ventricle. That being said,
hemorrhage frequently is widespread without a
discernible pattern.
The lesion illustrated on this MR image (arrow)
showed syncytial and epithelial cells with indistinct cytoplasmic borders and whorl-like structures
on histopathological analysis. What is the diagnosis represented?
A. Hemangiopericytoma
B. Lymphoma
C. Schwannoma
D. Meningioma
D. Meningioma
The pathological description provided in the
question is that of a meningioma. Meningiomas
represent the most common primary intracranial
tumors in adults and most frequently are parafalcine or seen along the sphenoid wings. About
10% occur in the parasellar region. Meningiomas
can arise primarily within the cavernous sinus or
involve it secondarily. The patient’s presentation
depends on the neurovascular structures involved.
Patients commonly present with oculomotor,
visual, or trigeminal symptoms. (A) Hemangiopericytomas are rare intracranial lesions. Microscopically, one can find uniform spindle cells with
intratumoral staghorn vessels. On imaging, they
commonly present as a large and aggressive duralbased mass. (B) Secondary lymphomas are more
common than primary lymphomas in the central
nervous system. The great majority of primary
central nervous system lymphomas are of the
B-cell type and occur in the parenchyma. Most
secondary lymphomas affect the leptomeninges
but also may occur in the brain. Dural lymphomas
are rare. (C) Schwannomas arise from Schwann
cells and are seen in adults. Microscopic exam
shows spindle cells with ill-defined cytoplasm and
dense chromatin sometimes associated with Verocay bodies. Intracranial schwannomas most commonly are related to the vestibular nerve followed
by the trigeminal and facial nerves. In the parasellar region, trigeminal schwannomas predominate
What is the origin of the lesion depicted on these
MR images?
A. Embryonic endoderm
B. Embryonic ectoderm
C. Notochord
D. Mesoderm
E. Arachnoid cap cells
A. Embryonic endoderm
This is the characteristic location of a colloid
cyst, which derives from embryonic endoderm
and nearly always is situated in the anterosuperior
aspect of the third ventricle. These lesions may
be associated with obstruction of the foramina of
Monro, which can be acute and lead to rapid herniation and death. They often are hyperdense on CT,
and their MRI signal characteristics vary depending on the degree of proteinaceous contents; those
with lower T2 signal tend to be more viscous. The
cyst is bright on both the noncontrast T1-weighted
and FLAIR images shown in this case. (B, D) Colloid
cysts derive from embryonic endoderm. (C) Tornwaldt cysts, among other lesions, are derived from
the notochord. (E) Arachnoid cap cells give rise to
meningiomas.
What is a characteristic of the pericallosal lesion
on these MR images of the brain?
A. Arises from arachnoid cap cells
B. Calcification is common
C. Contains dermal appendages
D. Demonstrates an alanine peak on MR
spectroscopy
B. Calcification is common
The location and homogeneously bright T1 signal intensity of the mass displayed along with
signal suppression on the fat-saturated T2 image
are most consistent with a pericallosal lipoma (tubulonodular type). Note that the image to the left
is without intravenous contrast (there is no mucosal enhancement in the nasopharynx or pituitary
gland). Calcification is common, particularly when
there is callosal dysgenesis, which is associated
more frequently with tubulonodular lipomas. Curvilinear lipomas have a low incidence of associated
anomalies. Note arachnoid cysts posterior to the
corpus callosum and in the posterior fossa compressing the cerebellum. The callosal splenium is
short. (A) Meningiomas arise from arachnoid cap
cells. Lipomas develop from anomalous differentiation of the meninx primitiva. (C) Dermoids contain
dermal appendages. Although they characteristically show areas of fat signal intensity, they are
more heterogeneous than lipomas and commonly
show dark areas of T2 hypointensity and fluid–fat
levels. Dermoids have a predilection for the midline, whereas lipomas tend to occur along infoldings of the subarachnoid space. (D) Meningiomas
demonstrate an alanine peak on MR spectroscopy
at short TE values.
The head CT shown in this image is compatible
with what pathology:
A. Abscess
B. Neoplasm
C. Acute infarct
D. Contusion
E. Old infarct
C. Acute infarct
There is hypoattenuation involving the left
insula and lateral basal ganglia in a patient with
an acute middle cerebral artery infarct. Note two
hyperdense dots in the left sylvian fissure (the
“MCA dot” sign), consistent with thrombosed M2
branches. (A) There is no defined fluid collection
to suggest an abscess. (B) An infiltrative neoplasm
potentially can mimic an infarct particularly on CT.
(D) Contusions in a patient with trauma usually
are peripheral and cortical but may vary in size
and involve the subcortical white matter. They
do not follow a vascular distribution and would
not explain the hyperdense vessels. (E) Old infarcts
usually show lower attenuation and well-circumscribed margins, with variable degrees of volume
loss and wallerian degeneration.
A man with lethargy, confusion, and one episode
of seizures underwent an MRI of the brain, shown
in these images. What is the likely diagnosis?
A. Infiltrative glioma
B. Acute infarct
C. Osmotic demyelination
D. Brainstem encephalitis
C. Osmotic demyelination
The axial FLAIR image accompanying the question shows a triangular hyperintensity in the
mid-posterior pons that demonstrates peripheral
enhancement on the coronal postcontrast image.
This is a characteristic location and presentation
for osmotic demyelination, which commonly is seen in alcoholics after rapid correction of hyponatremia, as well as in advanced liver disease, various
causes of malnutrition, and burns. Fifty percent of
patients show abnormalities in the pons, and the
rest of the lesions are extrapontine, occurring in
the basal ganglia, thalami, brainstem, and corpus
callosum. Lesions usually do not enhance, although
ring enhancement of pontine lesions has been
observed in the acute phase, as in this case. (A) An
infiltrative glioma would have some degree of mass
effect. The discrete central location and triangular
configuration of the lesion in this case is more
consistent with osmotic demyelination. (B) Infarction usually does not cross the midline except for
some infarcts from perforator vessels. The triangular shape and central location of the lesion in this
case are much more likely to be related to osmotic
demyelination. (D) Edema associated with brainstem encephalitis likely would show mass effect
and would be either asymmetric or diffuse.
An infant involved in a motor vehicle collision is
brought to the emergency department where he
underwent a CT examination of the head, shown
in this image. There is no evidence of intracranial
hemorrhage, and the patient is neurologically intact.
What is a characteristic of this patient’s lesion?
A. Immediate surgical elevation is warranted.
B. There is an increased risk of dural tears.
C. Elevation decreases the incidence of posttraumatic seizures.
D. There is a low risk of cortical laceration.
E. It represents the most common type of pediatric skull fracture.
B. There is an increased risk of dural tears.
Depressed skull fractures are associated with an
increased risk of dural tears. (A) Most pediatric
skull fractures can be managed expectantly if
they are depressed less than 1 cm, they are closed,
there is no associated intracranial hemorrhage,
and the patient is neurologically intact. (C) There
is no evidence that surgical elevation decreases the
incidence of posttraumatic seizures, as any potential cortical damage occurs at the time of injury (D) Depressed skull fractures have an increased risk
of cortical laceration. (E) Linear fractures are the
most common type of skull fractures, followed by depressed and basilar fractures.
A contrast-enhanced T1-weighted MR image of the
thoracic spine is shown here. What is the likely
diagnosis?
A. Epidermoid
B. Traumatic pseudomeningocele
C. Arachnoid cyst
D. Neurenteric cyst
D. Neurenteric cyst
This is a complex, cystic lesion with a component projecting into and expanding the spinal canal
and a second component projecting into the posterior mediastinum. The inferior aspect of the lesion
is partially intramedullary. Note also congenital
vertebral anomalies with incomplete segmentation
and a small size of multiple adjacent thoracic vertebrae. This constellation of findings is most consistent with a neurenteric cyst. These lesions result
from incomplete resorption of the neurenteric
canal, and when they occur in the spine, they are
most commonly thoracic. (A) Epidermoid tumors
in the spine may be developmental or acquired,
and occur most commonly in the lumbar region.
They rarely may be associated with spinal malformations such as hemivertebrae. (B) A traumatic
pseudomeningocele would not result in congenital
vertebral anomalies, and its contents would follow
cerebrospinal fluid signal on all sequences. (C) An
arachnoid cyst is not associated with vertebral
anomalies, although it could result in osseous
remodeling due to slow growth.
The lesions demonstrated on these MR images
likely represent:
A. Acute demyelination
B. Metastases
C. Multifocal glioblastoma
D. Multifocal abscesses
E. Vasculitis
A. Acute demyelination
These lesions demonstrate the typical appearance of acute tumefactive demyelination: concentric rings of different intensities on the FLAIR
image, a periventricular configuration along perimedullary veins (somewhat perpendicular to the
lateral ventricles), and, most importantly, an incomplete ring of enhancement on the postcontrast T1
images. (B) Metastases are a cause of multifocal
enhancing lesions, but the presence of incomplete
ring enhancement would be unusually rare, as
would be the perimedullary configuration of the
lesions (metastases favor the gray matter–white
matter junction and vascular border zones). In addition, metastases likely would incite a significant amount of surrounding edema for the size
of these lesions. (C) Multifocal glioblastoma likely
would have a more heterogeneous and infiltrative
appearance rather than the discrete lesions in
the distribution described above. (D) Multifocal
abscesses would not present with an incomplete
ring of enhancement, and the perimedullary/
periventricular distribution seen in this case would
be unusual for abscesses. Abscesses also demonstrate central restricted diffusion, whereas tumefactive demyelination may demonstrate restricted
diffusion peripherally. (E) Vasculitides can result
in multifocal white matter lesions and infarcts.
Mural enhancement sometimes can be demonstrated on high-resolution vessel wall imaging. An
incomplete ring enhancement is not seen.
A 55-year-old man became confused and hypotensive following a diagnostic angiographic procedure
with difficult groin access. Emergent CT of the
head was noncontributory. A noncontrast CT of
the abdomen is shown here. What is the patient’s
most likely diagnosis?
A. Urinoma
B. Bowel infarction
C. Ascites
D. Hematoma
D. Hematoma
The noncontrast CT image accompanying the
question shows a large and heterogeneous retroperitoneal mass on the left side, with areas that are
hyperdense relative to the adjacent psoas muscle,
consistent with a retroperitoneal hematoma. This
is an infrequent but important complication with a
reported incidence between 0.5% and 5% that can
be seen following difficult arterial or venous groin access, particularly in patients who are anticoagulated. (A) An urinoma would not be expected after
femoral puncture. It also would appear more homogeneous and demonstrate lower density on CT
unless it was infected. (B) The image shows a retroperitoneal process that is displacing the bowel
loops anteriorly. (C) The image shows fluid that is
not within the peritoneal cavity. The location of
this hematoma is retroperitoneal, which can be
suspected following difficult groin access and also
by noticing mild enlargement of the left psoas
muscle and stranding of the surrounding retroperitoneal fat.
What is a characteristic of the lesion depicted in
this CT image?
A. Limited by sutures
B. Usually crosses the midline
C. Most commonly due to an arterial injury
D. Occurs between the inner and outer layers of
the dura
E. Limited by dural reflections
E. Limited by dural reflections
This is an acute subdural hematoma with hyperdense blood, resulting in a shift of midline structures. These lesions occur between the inner layer
of the dura and arachnoid membranes, and therefore are limited by dural reflections including the
falx cerebri and tentorium cerebelli. (A) Epidural,
not subdural, hematomas occur between the outer
layer of the dura and the calvaria and are thus
limited by tight dural attachments at the sutures.
(B) Supratentorial subdural hematomas cannot
cross the midline, as they are limited by the dural
reflections that form the falx cerebri. (C) Subdural
hematomas are most commonly due to the tearing of bridging veins due to a shearing injury. For
this reason, they are more common in older brains
where these veins may be stretched due to cerebral
atrophy. (D) Subdural hematomas occur between
the dura and arachnoid membranes.
A 52-year-old woman with a history of decompressive left hemicraniectomy for a large middle
cerebral artery territory infarction presents with
new-onset headache, vomiting, and lethargy. Her
CT scan is shown in this image. What is the next
appropriate step for her management?
A. Cranioplasty
B. Surgical evacuation
C. Contralateral craniectomy
D. Lumbar spinal fluid drain
A. Cranioplasty
“Sunken skin flap” or “trephine” syndrome refers
to an uncommon late postoperative complication
following decompressive craniectomy in which
there is marked concavity of the skin flap and paradoxical cerebral herniation. The pathophysiology
is presumed to be related to exposure of the intracranial contents to atmospheric pressure and a negative pressure gradient that may be exacerbated by
cerebrospinal fluid hypovolemia. Neurologic deterioration in this context is a surgical emergency,
and the goal of treatment is to restore intracranial pressure, which generally can be achieved by
cranioplasty. Other measures include placing the patient in the Trendelenburg position, tilting the head toward the craniectomy site, an epidural blood patch, or clamping the ventricular shunt
tubing. (B) There are no collections to evacuate in
this patient. (C) Contralateral craniectomy would
not help restore the intracranial pressure. (D) Lumbar spinal fluid drain would be contraindicated in
a patient with a herniation syndrome. Lumbar epidural blood patches may be useful in the management of sunken flap syndrome
A lumbar spine radiograph from a patient with a
history of posterior spinal fusion surgery and progressive back pain is shown in this image. What
surgical procedure is indicated?
A. Hardware removal due to diskitis/osteomyelitis
B. Pedicle subtraction osteotomy
C. Hardware revision due to loosening
D. Anterior interbody fusion
B. Pedicle subtraction osteotomy
This patient has sagittal imbalance due to loss of
the expected lumbar lordosis, with acute kyphotic
angulation centered at L1 above the level of the
fusion. A pedicle subtraction osteotomy at L1
potentially could restore lordosis by means of a
wedge-shaped vertebral resection and shortening
of the posterior column. (A) Although other modalities such as MRI are more sensitive, there is no
radiographic evidence of diskitis/osteomyelitis that
would manifest as erosive changes centered at the
disk space with variable degrees of end-plate and vertebral destruction. (C) There is no visible perihardware lucency to suggest loosening on this exam. (D) Anterior interbody fusion would not restore lumbar lordosis.
A 56-year-old woman with a history of progressive headaches presented after a seizure episode.
An MRI examination of the brain was performed,
shown in this image. What is an expected imaging
feature of the lesion?
A. Increased relative cerebral blood volume
B. Elevated apparent diffusion coefficient values
C. Elevated N-acetylaspartate levels
D. Decreased choline levels
E. Elevated alanine levels
A. Increased relative cerebral blood volume
The necrotic mass shown with heterogeneous
enhancement in an adult patient most likely represents a glioblastoma, which may arise de novo
or from degeneration of a lower grade glioma.
Glioblastomas show increased relative cerebral
blood volume and blood flow on MR and CT perfusion studies and increased permeability values on
advanced MR imaging. Approximately 10% are
multicentric. They may hemorrhage and rarely
calcify. (B) Because glioblastomas are highly cellular tumors, their solid components tend to show
restricted diffusion and decreased (not elevated)
apparent diffusion coefficient values. (C, D) On MR
spectroscopy, glioblastomas and other high-grade
gliomas show decreased N-acetylaspartate levels
(reflecting neuronal loss) and elevated choline
levels due to increased cellular turnover. Glioblastomas may show elevated lipid and lactate levels
secondary to necrosis. (E) Elevated alanine levels are a characteristic feature of meningiomas on MR spectroscopy.
