Chapter 12 CT/MRI Brain Flashcards
1
Q
What is the main reason CT imaging of the caudal fossa can be challenging?
A) Low signal from brainstem structures
B) Motion artifacts due to respiratory movement
C) Beam hardening artifacts from adjacent dense bone
D) Inability of CT to detect fluid
A
C) Beam hardening artifacts from adjacent dense bone
2
Q
Which of the following best describes the beam hardening artifact seen on CT?
A) Increased brightness of soft tissue adjacent to bone
B) Deformation of bone margins due to overexposure
C) Incomplete image acquisition from skipped slices
D) Streaks or dark bands caused by selective absorption of low-energy X-rays
A
D) Streaks or dark bands caused by selective absorption of low-energy X-rays
3
Q
What percentage of English bulldogs have an intact septum pellucidum?
A
25%
4
Q
Which type iof supracollicular fluid accumulation this?
A
Type 1
5
Q
Which type iof supracollicular fluid accumulation this?
A
Type 2
6
Q
Which type iof supracollicular fluid accumulation this?
A
Type 3
7
Q
Fluid accumulations within the developing brain: Focal fluid accumulations are termed _________________
whereas extensive uid accumulations are termed ________________.
A
porencephaly
hydranencephaly
8
Q
Dandy Walker syndrome is a developmental disorder
whereby there is failure of development of the __________________.
A
caudoventral aspect of the cerebellar vermis
9
Q
_____________________ is a developmental disorder
whereby there is failure of development of the caudoventral aspect of the cerebellar vermis
A
Dandy Walker syndrome
10
Q
Which type of holoprosencephaly is most commonly reported in dogs?
Which other change is associated with this?
Which dog breed is overrepresented?
What is the typical presentation/biochemical change?
A
Lobar HPE
Corpus callosum agenesis
Mini Schnauzers and SBTs
Hypodypsic hypernatremia
11
Q
What is HPE (holoprosencephaly)?
A
failure of the cerebral hemispheres to bifurcate
12
Q
A
13
Q
What is lissencephaly?
A
Failure to develop gyri, resulting in smoother outer cortical surface
14
Q
Which breed is overrepresented for lissencephaly?
A
Lhasa Apso
15
Q
A
Dandy Walker variant
16
Q
A
Lissencephaly
17
Q
A
Corpus callosum dysgenesis
18
Q
Which (location and pathophys) T1w hyperintensities could occur with hepatic insufficiency?
A
Manganese deposition in the lentiform nuclei
19
Q
In An Alaskan Husky, Bull terrier or Yorkie, what would the following findings indicate?
Bilaterally symmetrical regions of T2/FLAIR hyperintensity within the central aspect of the thalamus +/- midbrain, medulla
A
Subacute necrotising encephalopathy
20
Q
A
hypernatremia; T2w hyperintense white matter between internal capsule and thalamus
21
Q
Which conditions fall under the category of MUE/MUO/MUA?
A
granulomatous meningoencephalomyelitis (GME)
necrotizing meningoencephalomyelitis (NME)
necrotizing leucoencephalitis (NLE)
22
Q
Which non-infectious meningoencephalomyelitides can be confirmed without histopath?
A
steroid-responsive meningitis-arteritis (SRMA)
eosinophilic meningoencephalitis (EME)
23
Q
Which breed is overrepresented for idiopathic hypertrophic pachymeningitis?
A
Greyhound
24
Q
For which type of meningitis are Greyhound overrepresented?
A
idiopathic hypertrophic pachymeningitis
25
NCL
26
Cerebellar abiotrophy
27
What % of MRI studies in dogs with inflammatory CSF are normal? (study with 25 dogs)
24%
28
Which regions are most commonly affected by post-ictal changes?
Piriform and temporal lobes
29
Post-ictal changes are... enhancing or non-enhancing?
Non-enhancing
30
6y DSH
seizures, ataxia and vestibular
thiamine deficiency, T2w hyperintensities in thalamus and colliculi
31
T1w pre-con
cat with PSS, manganese deposition in basal ganglia and lentiform nuclei
32
Yorki
subacute necrotising encephalopathy, thalamus and brainstem
33
What kind of meningiomas are common in the optic chiasm and suprasellar regions?
basal and plaque-like
34
Which species can get multiple meningiomas?
cats
35
Which extracranial (not brain parenchyma) change is typical in cats with meningiomas?
adjacent hyperostosis
36
Describe classic meningioma findings
Broad-based
Peripheral
Strong CE
Dural tail
Hyperostosis
37
PPV of dural tail for meningioma?
94%
38
CPTs occur most commonly in which location?
3rd ventricle, lateral recess of 4th
39
meningioma or lymphoma?
lymphoma
40
What is the most common intravrentricular tumor? What are other types?
CPT (papilloma, carcinoma)
Less common
- Ependymoma
- Meningioma
- Glioma
41
What are some CPT secondary effects/ complications?
Haemorrhage
CSF overproduction
42
In which species are pituitary tumors more common?
Dogs
(rare in cats)
43
How does a functional pituitary tumor usually manifest clinically?
PDH - Cushing's
44
What percentage of neuro-normal PDH dogs have a pituitary mass of 4-12mm height?
60%
45
What is the cut-off for the term micro- and macrotumor when talking about pituitary masses?
>10mm height is a macrotumor
46
Gliomas arise from the____________.
neuropil (accuracy? don't they originate from glial cells?)
47
Name the types of gliomas
Oligodendroglioma
Astrocytoma
Glioblastoma multiforma
48
Gliomas are prevalent in which type of dog?
Brachycephalics - bulldogs, Boston, Boxer
49
Which type of brain tumor is diffuse and results in relative preservation of the intracranial architecture?
Gliomatosis cerebri; there may be T2w and FLAIR hyperintensity with some mass effect
50
Gliomatosis cerebri is classifed as a ___________ tumor of __________ (cell) origin.
Neuroepithelial
Astrocytic
51
Trigeminal nerve PNST dysfunction cause atrophy of which muscles?
temporal
masseter
pterygoid
digastricus
52
Trigeminal nerve arises from the:
pons and caudal mesencephalon
53
Which of the following best explains how trigeminal nerve neoplasia can lead to noninfectious middle ear effusion in dogs?
a. Direct extension of the tumor into the tympanic bulla
b. Overproduction of cerumen by the external auditory canal
c. Loss of tensor veli palatini function leading to Eustachian tube dysfunction
d. Obstruction of the external auditory canal by the tumor mass
c. Loss of tensor veli palatini function leading to Eustachian tube dysfunction
54
Explain how a tumor affecting the trigeminal nerve can result in sterile fluid accumulation in the middle ear.
The mandibular branch (V3) of the trigeminal nerve innervates the tensor veli palatini muscle, which is responsible for intermittently opening the Eustachian tube. This tube normally drains mucus and fluid secreted by the middle ear lining. When a trigeminal nerve tumor disrupts innervation to this muscle, the Eustachian tube fails to open properly, leading to passive fluid accumulation in the middle ear without infection
55
__________________ is an uncommon extra-axial
tumor that has imaging characteristics similar to meningioma,
including a dural tail.
Histiocytic sarcoma
56
Histiocytic sarcoma is an ________-axial
tumor
extra or intra
57
Which tumors are associated with a dural tail?
meningioma, also histiocytic
58
In which tumors is meningeal enhancement remote from the tu-
mor epicenter not an uncommon finding?
Histiocytic sarcoma
59
Which is the most common metastatic lesion in the brain?
hemangiosarcoma
60
Brain tumors do not
commonly extend rostrally through the cribriform plate into
the nasal cavity. A rare neural tumor that does traverse the
cribriform plate is an ______________.
olfactory neuroblastoma
61
Infarcts occur most commonly in the _____________ (which part of the brain)
cerebellum
62
Which of the following is most characteristic of an acute cerebral infarct compared to a glioma?
a. Avid contrast enhancement
b. Prominent mass effect within hours of onset
c. Initial absence of mass effect
d. Heterogeneous T1 hyperintensity
c. Initial absence of mass effect
Explanation: In acute infarction, mass effect is usually absent early but may develop over 3–5 days due to vasogenic edema. Gliomas often have mass effect from the outset due to tumor volume and edema.
there is usually ill-defined T2 hyperintensity, T1 hypointensity, no mass effect, and little to no initial contrast enhancement
63
Diffusion-weighted MRI helps differentiate infarcts from tumors by assessing which of the following?
a. Electrical conductivity of axons
b. Water molecule temperature
c. Directionality of cerebrospinal fluid flow
d. Brownian motion of water molecules in tissue
Correct Answer: ✅ d. Brownian motion of water molecules in tissue
Explanation: DWI quantifies the random motion (Brownian motion) of water molecules. Restricted diffusion (e.g., in cytotoxic edema from infarct) appears bright on DWI and dark on ADC.
64
When Might Mass Effect Develop in an Infarct? In a cerebral occlusive / ischemic infarct, mass effect due to vasogenic edema typically develops:
a. Within 1–2 hours
b. After 12 hours
c. Between 3 to 5 days
d. Only if hemorrhage occurs
c. Between 3 to 5 days
Explanation: Vasogenic edema develops in the subacute phase, usually peaking between days 3–5 post-infarct.
65
Approx. age of this haemorrhage - T1w pre and post
at least 3 days, less than 14 days (when methemoglobin turns into hemosiderin)
66
fracture with epi/sub-dural haemorrhage
67
In which haemorrhage phase is it T2w hyperintense?
Hyperacute <24h
Late subacute 7-14days
68
Age this haemorrhage (T2 and GRE)
either hyperacute (<24h) or late subacute (7-14days)
69
T2, ADC, T1w pre and post
R caudate nucleus, ischemic event
70
How and when can you use DWI to differentiate a tumor from an ischemic infarct? What else can you use?
A tumor will have more facilitated diffusion, while an infarct while have restricted (at first, up to 3-5 days).
A tumor will also usually have mass effect, which is absent in an infarct (for the first 3-5 days) until it d.
71
Most common underlying causes of haemorrhagic infarcts
hypertension
coagulopathy e.g. thrombocytopenia
72
Differences in MRI appearance between ischemic and haemorrhagic infarct
Hemorrhagic - more heterogenous, larger volume
73
Low signal in T2-weighted spin-echo and GRE images is not specific
for hemorrhage and may also be seen with _________________.
mineralization
gas
fibrous tissue
iron deposits
74
Acute hemorrhage is _________________ (hyper/hypo) to brain tissue in precontrast CT imaging due to the ______________. The average HU of hemorrhage is between __________, whereas those of
gray and white matter are ________________ and _______________,
respectively.
hyperattenuating, high hemoglobin content.
Haemorrhage: 60 and 100
grey: 30 to 40
white: 20 to 30
75
76
Which of the following statements is true regarding MRI imaging techniques?
A) In T2-weighted FLAIR sequences, free fluid appears bright, while hydrated lesions (proteinaceous or inflammatory lesions) are suppressed.
B) In T1-weighted sequences, hydrated lesions typically appear bright due to rapid T1 relaxation.
C) Gadolinium contrast in T1-weighted sequences increases signal intensity in areas of blood-brain barrier disruption and altered perfusion
D) On FLAIR CSF can not be distinguished from cystic meningioma, dermoid, epidermoid and arachnoid cysts.
C.
In T1-weighted sequences, hydrated lesions appear dark (hypointense) due to slow T1 relaxation, not bright. Bright signal comes from fat or methemoglobin, which arise from tissues having rapid T1 relaxation.
77
Which of the following best describes the role of a T2-weighted FLAIR sequence in MRI imaging?
A) It enhances the signal from free fluid, making it easier to identify CSF within the ventricles.
B) It suppresses the signal from free fluid, aiding in the distinction of hydrated lesions from CSF.
C) It is primarily used to detect regions of rapid T1 relaxation, such as fat or methemoglobin.
D) It is the best sequence for evaluating extracranial anatomy after gadolinium administration.
B.
78
Which of the following substances is NOT T1W hyperintense?
A. Melatonin
B. Methemoglobin (Early subacute to early chronic)
C. Protein
D. Oxyhemoglobin (Hyperacute)
D.
My Best Friend is Pretty Cool:
M: melanin and methemoglobin
B: blood (i.e. methaemoglobin in subacute haemorrhage)
F: fat and slow flow
P: protein; paramagnetic substances (e.g. manganese, copper); posterior pituitary gland
C: contrast (i.e. gadolinium) and cholesterol
79
Which of the following statements about GRE images is true?
A. Extremely sensitive indicator of intracranial trauma, hemorrhagic tumors, hemorrhagic infarcts, coagulopathies, or hemorrhagic metastasis.
B. The image void is typically much larger than the actual lesion because of blooming
C. As hemorrhage is broken down, the magnetic properties of the ferric/ferrous ions
in hemoglobin metabolites cause a local field distortion that destroys the MR signal.
D. All the above are true.
D
80
What is the term for herniation of the cingulate gyrus across the midline due to brain compression?
A) Transtentorial herniation
B) Subfalcine herniation
C) Cerebellar herniation at the foramen magnum
D) Ventricular compression and obstruction
B.
- Midline shift --> leftward/rightward shift of the falx cerebri
- Subflacine herniation --> Leftward/rightward displacement of the cingulate gyrus across the midline
- Cerebellar herniation --> caudal displacement of the cerebellum into the foramen magnum
- Transtentorial herniation --> caudal displacement of the parahippocampal gyrus into the tentorium
81
What is the most common cause of congenital hydrocephalus?
A) Brain atorphy and CSF overproduction
B) Adult infection
C) Obstruction of normal CSF flow secondary to inherited malformation, perinatal infection which can lead to scarring that affects CSF reabsorption
D) Tumor growth in the ventricular system
C
82
In which group is agenesis of the septum pellucidum most frequently observed?
A) Small-breed dogs
B) Larger brachycephalic breeds
C) Cats
D) Patients with supracollicular fluid accumulation
B.
common, typically asymptomatic, finding. In one study, the septum pellucidum was considered intact in only 25% of English Bulldogs
83
Which pattern of supracollicular fluid accumulation involves enlargement of both the third ventricle and the quadrigeminal cistern with a visible separating membrane (likely 3rd ventricle wall, tela choroidea)?
A) Pattern 1
B) Pattern 2
C) Pattern 3
D) Pattern 4
B. Pattern 2
84
Focal intracranial fluid accumulations are termed _______, whereas extensive fluid accumulations are ________. Developmental porencephaly is due to a focal neuronal migration disorder and results in a gap in the developing cerebral hemisphere. Encephaloclastic porencephaly is an all-encompassing term describing ____ loss from various causes, including ischemia, infection, or trauma.
These accumulations of fluid usually communicate with the lateral ventricles or the _________________.
porencephaly, hydranencephaly, cortical, subarachnoid space
85
What is the primary structural abnormality in Dandy Walker syndrome (variant)?
A) Enlargement of the lateral ventricles
B) Failure of development of the caudoventral cerebellar vermis
C) Agenesis of the septum pellucidum
D) Flattening of the rostrodorsal cerebellum
B.
Leading to enlargement of the dorsocaudal fourth ventricle
86
Which pattern os supracollicular fluid represent this image of a dog?
Pattern 3
There is marked enlargement of the quadrigeminal cistern (black asterisk) resulting in flattening
of the rostrodorsal aspect of the cerebellum.
In pattern 1 there is enlargement of the suprapineal recess of the third ventricle.
87
Which disease represent this image of a 5-month-old DSH cat with seizures?
A) Lissencephaly
B) Lobar holoprosencephaly and disgenesis/agenesis of the corpus callosum
C) Chiari-like malformation
D) Mucopolysaccharidosis
A. there is an absence or severe lack of normal gyral formation resulting
in a smooth outer surface to the brain.
It results from failure of normal neural migration during fetal development. In dogs, the Lhasa Apso is overrepresented.
88
Which of the following cystic structures is most commonly located in the fourth ventricle or cerebellopontine angle?
A) Rathke cleft cysts
B) Craniopharyngiomas
C) Intracranial epidermoid or dermoid cysts
D) Chiari-like malformation cysts
C)
Dermoid cysts containing adnexa (e.g., hair) may have suspended low intensity
foci in all sequences. Often contain protein and keratin, therefore, do not null in FLAIR sequences. Typically, do not enhance, although ring enhancement may occasionally be present.
Rathke cleft cysts and craniopharyngiomas occur in the region of the sella turcica and are typically associated with anomalous development of the pituitary gland.
89
Which breed is most affected by Chiari-like malformation, with an estimated prevalence of up to 95%?
A) Miniature Schnauzer
B) Lhasa Apso
C) Cavalier King Charles Spaniel
D) Alaskan Husky
C.
90
What is a common consequence of caudal fossa crowding in Chiari-like malformation?
A) Development of porencephaly
B) Syringohydromyelia within the spinal cord
C) Agenesis of the corpus callosum
D) Symmetrical white matter disease
B.
91
Which form of holoprosencephaly has been described in dogs and is associated with dysgenesis/agenesis of the corpus callosum?
A) Alobar
B) Semilobar
C) Lobar
D) Midline
C.
Miniature schnauzers appear to be overrepresented for both dysgenesis of the corpus
callosum and lobar holoprosencephaly.
92
Which metabolic storage disease typically results in progressive cerebellar atrophy with increased conspicuity of cerebellar folia and atrophy?
A) Mucopolysaccharidosis
B) Neuronal cell lipofuscinosis
C) Cerebellar abiotrophy
D) Globoid cell leukodystrophy
C.
- Mucopolysaccharidosis and neuronal cell lipofuscinosis typically result in progressive juvenile cortical atrophy and hydrocephalus and an abnormally small corpus callosum, and in the latter, there is often severe peripheral meningeal thickening and enhancement
- Globoid cell leukodystrophy typically results in symmetrical white matter disease, mild hydrocephalus, and symmetrical contrast enhancement of the corpus callosum, internal capsule, and corona radiata.
93
What MRI finding is associated with thiamine deficiency in the brain?
A) Bilaterally symmetrical T1 hyperintensity in the basal ganglia
B) Bilaterally symmetric multifocal abnormalities in brain and brainstem nuclei
C) Symmetrical T2 hyperintensity in the thalamus
D) Severe peripheral meningeal enhancement
B. including the lateral geniculate nuclei, caudal colliculi, (IMAGES) vestibular
nuclei (under 4th ventricle), and others
94
T1W images of a 5-year-old DSH cat at the level of the basal ganglia and lentiform nuclei, what represent?
A. Necrotizing encephalopathy
B. Hepatic insufficiency associted with PSS
C. Hypernatremia correction, wine glass sign
D. MUE
B. The increase in T1 signal is thought due to a buildup of manganese, which is paramagnetic.
Necrotizing encephalopathy --> Alaskan husky, as well as Bull Terrier and Yorkshire. (Leigh syndorme in people). Bilaterally symmetrical regions of T2 and FLAIR hyperintensity within the central aspect of the thalamus. Additionally, focal T2 hyperintensity has been documented within the midbrain and medulla.
95
T2W image, 7y old mixed breed presented comatose. The patient was normal 3 h earlier. What is the most likely diagnoses?
Severe hypernatremia can result in typically bilaterally symmetrical increase in T2 signal in signal at the junction of the internal capsule and lateral margin of the thalamus.
96
What percentage of MR studies were normal in patients with CSF alterations consistent with inflammatory brain disease, according to the text?
A) 10%
B) 24%
C) 35%
D) 50%
B) 24%
Lamb CR, Croson PJ, Cappello R, et al. Magnetic resonance
imaging findings in 25 dogs with inflammatory cerebrospinal
fluid. Vet Radiol Ultrasound. 2005;46:17e22.
97
What is one of the typical imaging feature of intracranial feline infectious peritonitis?
A) Multifocal T2 hyperintense lesions in the cerebellum
B) Marked contrast enhancement of the ventricular lining
C) Symmetrical white matter hypoattenuation
D) Thickening of the corpus callosum
B
98
Which condition is characterized by marked thickening and fibrosis of the pachymeninges?
A) Feline ischemic encephalopathy
B) Idiopathic hypertrophic pachymeningitis
C) Intracranial feline infectious peritonitis
D) Bacterial pachymeningitis
B.
overrepresented in Greyhounds
99
What is a common MRI finding in chronic cases of encephalitis that reflects brain necrosis?
A) T1 hyperintensity in the brainstem
B) Compensatory hydrocephalus
C) Uniform ring enhancement
D) Nulling in FLAIR sequences
B.
100
Which group of dogs is more likely to have an immune-mediated etiology for meningoencephalitis?
A) Large breed dogs
B) Small breed dogs
C) Greyhounds
D) Dogs with chronic sinusitis
B.
101
Which diagnostic method is most commonly required to establish a definitive diagnosis of meningoencephalitis?
A) MRI alone
B) CT imaging
C) Cytologic and immunologic analysis of CSF
D) Pre- and post-contrast T1-weighted imaging
C.
102
Which subtype or subtypes of noninfectious meningoencephalomyelitis (NIME) have fairly distinct diagnostic characteristics and are not grouped in MUE?
A) Granulomatous meningoencephalomyelitis (GME)
B) Steroid responsive meningitis-arteritis (SRMA)
C) Necrotizing meningoencephalomyelitis (NME) and leucoencephalitis (NLE)
D) Eosinophilic meningoencephalitis (EME)
B and D
Three specific subtypes that can only be confirmed based on histopathology. These include GME, NME, and NLE
103
In which phase in this haemorrhage or hours/days given T1W pre- and post-contrast images?
A) Hyperacute, < 24 h
B) Acute 1-3 days
C) Chronic >14 days
D) Early to late subacute, between > 3 and > 7days
d. The precontrast T1-hyperintense region in A is hemorrhage of at least 3 days duration. Both intracellular and extracellular methemoglobins are inherently T1 hyperintense. Other substances that are T1 hyperintense are the normal neurosecretory granules within the pituitary gland, fat, melanin, proteinaceous fluids, and some plasma cell tumors. There is no enhancement of the lesion (B), but normal vascular enhancement is apparent adjacent to the lesion.
104
Which brain regions are most commonly affected by reversible seizure-associated brain edema?
A) Frontal and occipital lobes
B) Piriform and temporal lobes
C) Cerebellum and brainstem
D) Parietal and piriform lobes
B
Typically, the changes are bilateral, but changes can also be unilateral and occur elsewhere,
including the region of the cingulate gyrus.
105
106
Choroid plexus tumors most commonly occur in which locations?
A) Cerebral hemispheres and retrobulbar space
B) Third ventricle and lateral recess of the fourth ventricle
C) Optic chiasm and suprasellar region
D) Cerebellopontomedullary region
B.
107
A key complication of choroid plexus tumors is:
A) Hyperostosis of adjacent bone
B) Obstructive hydrocephalus due to their intraventricular location
C) Diffuse infiltration of the neuropil
D) Minimal contrast enhancement on imaging
B.
Some will cause an overproduction of CSF, which exacerbates any obstructive process.
108
Pituitary tumors in dogs are typically characterized by:
A) Growth ventrally into the brainstem
B) Dorsocaudal growth leading to compression of the third ventricle and hypothalamus
C) Diffuse infiltration with no contrast enhancement
D) Compression of the dorsal aspect of the third ventricle and hypopthalamus
B.
Dorsal aspect of the third ventricule would be common in coroid plexus masses growing from this ventricle.
109
What is the typical size range of pituitary tumors in dogs with pituitary-dependent hyperadrenocorticism (PDH) but without neurologic signs?
A) 1 to 3 mm
B) 4 to 12 mm
C) 13 to 20 mm
D) Greater than 20 mm
B. up to 60% of dogs with PDH but without neurologic signs have a pituitary tumor 4 to 12 mm in diameter at greatest vertical heigh
110
Gliomas are particularly common in which dog breeds?
A) Dachshund and Beagle
B) Boxer, Boston Terrier, and Bulldog
C) Labrador Retriever and Golden Retriever
D) German Shepherd and Rottweiler
B. brachycephalic breeds
111
Which of the following is a typical MR feature of gliomas?
A) Uniform and marked contrast enhancement with well-defined margins
B) Minimal or no contrast enhancement with varying degrees of perilesional edema
C) Intraventricular location with CSF overproduction
D) Peripheral location with a dural tail sign
B. many gliomas do not enhance, or enhance only minimally, are often ill-defined, and have varying degrees of perilesional edema
112
Gliomatosis cerebri is characterized by:
A) Discrete, well-defined masses with intense contrast enhancement
B) Diffuse infiltration of the CNS with relative preservation of neural tissue architecture
C) Intraventricular growth causing obstructive hydrocephalus
D) Hyperostosis of adjacent bone
B.
113
An important differential for meningeal enhancement or masses, besides meningioma, is:
A) Choroid plexus tumor
B) Round cell neoplasia (e.g., histiocytic sarcoma and lymphoma)
C) Pituitary microtumors
D) Olfactory neuroblastoma
B.
114
Which tumor is most likely to traverse the cribriform plate into the nasal cavity, (otherwise is rare)?
A) Meningioma
B) Glioma
C) Olfactory neuroblastoma (esthesioneuroblastoma)
D) Choroid plexus tumor
C
115
The most common location for occlusive brain infarcts is:
A) Forebrain
B) Brainstem
C) Cerebellum
D) Optic chiasm
C.
116
What is a typical MR characteristic of an acute cerebellar infarct (1-3 days)?
A) T2 hypointensity with significant mass effect
B) Triangular or segmental T2 hyperintensity that persists in the FLAIR sequence
C) T1 hyperintensity with marked contrast enhancement
D) Diffuse signal void on GRE sequences
B.
117
An important clinical differential for brainstem or cerebellar infarction is:
A) Glioma
B) Idiopathic peripheral vestibular disease
C) Choroid plexus tumor
D) Meningioma
B.
118
Which feature INITIALLY helps differentiate a cerebral infarct from a glioma on MRI?
A) Presence of marked contrast enhancement
B) Lack of mass effect with an infarct
C) Diffuse infiltration of the neuropil
D) Hyperintensity on T1-weighted images
B.
119
In acute infarction, restricted water diffusion on diffusion-weighted imaging is due to:
A) Overhydration of brain cells from failure of the adenosine triphosphate pump
B) Increased vascularity at the lesion periphery
C) Unrestricted movement of water molecules
D) High levels of extracellular hemosiderin
A. in acute infarction, brain cells become overhydrated from failure of the adenosine triphosphate pump, resulting in restricted movement of water
120
How long does restricted water diffusion typically last in an infarct, limiting the utility of diffusion-weighted imaging?
A) 1 to 3 days
B) 3 to 5 days
C) 7 to 10 days
D) More than 14 days
B. restricted water diffusion in an infarct typically only lasts up to 3 to 5 days post infarct
121
Hemorrhagic infarcts are most commonly associated with:
A) Hypercoagulable states like Cushing disease
B) Hypertension, thrombocytopenia, or other coagulopathies
C) Idiopathic peripheral vestibular disease
D) Chronic trauma
B.
If occlusive infarct is suspected, the patient should be evaluated for conditions resulting in a hypercoagulable state (e.g., Cushing disease) and loss of antithrombin III.
122
In the early subacute phase (>3 days) of a maturing hematoma, the MR appearance shows:
A) T1 isointense or hypointense, T2 hyperintense
B) T1 hyperintense, T2 hypointense
C) T1 hyperintense, T2 hyperintense
D) T1 hypointense, T2 hypointense
B. in the early subacute phase (>3 days), hemoglobin is intracellular methemoglobin, resulting in "T1 hyperintense, T2 hypointense.
123
The average Hounsfield units (HUs) of hemorrhage on CT imaging are:
A) 20 to 30
B) 30 to 40
C) 60 to 100
D) 100 to 150
C.
- whereas those of gray and white matter are in the range of 30 to 40 and 20 to 30.
- acute hemorrhage is hyperattenuating to brain tissue in precontrast CT imaging due to the high hemoglobin conten
