from AIM: Brant: Section XI: Pedia Flashcards
Meaning of ALARA
As Low As Reasonably Achievable
T/F: At least 20 separate radiographs are required for a skeletal survey for child abuse
True
T/F: One key difference between adult and pediatric fluoroscopic studies is that double-contrast GI studies are rarely performed in children who either cannot tolerate the distention or may not be able to maintain the gas.
True
Modality considered to be the workhorse of pediatric imaging
Ultrasound
At all ages, the ____ is probably the most important factor in obtaining high-quality images in ultrasound.
Ultrasound technologist
Myelination begins in the ____ fetal month and continues throughout life.
5th
In a normal infant, myelination appears complete on conventional T1-weighted images (T1WI) by around ____ months, on T2 weighted images (T2WI) by ____ months, and on FLAIR images by ____ months of age.
12, 24, 40
We rely on T1WI for myelin evaluation in the ____ year of life and T2WI in the ____ year.
first, second
By what age the appearance of white matter myelination in T1 similar to that of an adult?
1 year of age
What fissure first develops, and at what age?
Sylvian fissure at 16-18 AOG
At what AOG do all primary and seconday sulci are formed?
34 weeks AOG
While the normal neonatal corpus callosum can appear quite thin, the splenium should be at least as thick as the ____ by 1 year of age.
Genu
Developmental abnormalities of the corpus callosum are referred to as ____, a spectrum that ranges from complete agenesis through partial agenesis to hypoplasia of the corpus callosum.
Dysgenesis of the corpus callosum
In complete agenesis of the corpus callosum, the lateral ventricles have a parallel orientation, with posterior dilation termed ____
Colpocephaly
In corpus callosum dysgenesis, the axons that would normally have crossed the midline instead line up in an anterior to posterior configuration along the medial aspect of each lateral ventricle; these tracts are called ____
Probst bundles
Give the sign and name the disease entity
Texas longhorn appearance of lateral ventricles in Corpus Callosum Agenesis (or Moose head appearance)
Diagnosis
Interhemispheric lipoma in Corpus Callosum Dysgenesis
T/F: Optic nerve hypoplasia is more reliably diagnosed on ophthalmologic examination, as only 50% of affected patients have appreciable optic nerve hypoplasia on MRI.
True
It encompasses a spectrum of malformations caused by abnormalities of differentiation and midline cleavage of the prosencephalon during the 5th gestational week.
Holoprosencephaly
Hallmark of holoprosencephaly
Abnormal communication of gray and/or white matter across midline
Implies complete absence of cleavage with anterior displacement of the cerebra tissue into a “pancake” configuration and a large monoventricle that expands posteriorly into a dorsal cyst
Alobar holoprosencephaly
This structure can be partially present in lobar holoprosencephaly but not in alobar prosencephaly
Anterior falx cerebri
It is characterized by cerebellar tonsillar protrusion below the foramen magnum in the absence of an open spinal dysraphism or intracranial mass effect.
Chiari I
Cerebellar tonsillar protrusion is usually defined as tonsillar descent ≥5 mm below the McRae line which is the line drawn from the ____ to the ____
Basion to opisthion
What do you call this entity pointed by the white arrow?
Syrinx
Give 2 signs and diagnosis
Lemon sign and banana sign
Chiari II Malformation
The malformation can be identified on prenatal ultrasound by bifrontal concavity of the calvarium (“lemon” sign) and a flattened cerebellum wrapping around the brainstem (“banana sign”).
This malformation comprises a constellation of imaging findings in the brain associated with an open spinal dysraphism (either a myelomeningocele or myelocele).
Chiari II malformation
It is rare and is characterized by a cervico-occipital encephalocele containing posterior fossa contents,
Chiari III malformation
This group of posterior fossa malformations includes a number of abnormalities characterized by varying degrees of vermian hypoplasia and malposition in association with posterior fossa cysts.
Dandy–Walker Continuum
In characterizing Dandy–Walker Continuum, the following structures are evaluated:
a. Posterior fossa
b. Vermis
c. Cisterna magna
d. All of the above
d. All of the above
The classic Dandy–Walker malformation is a triad of
Complete or partial agenesis of the vermis
Cystic dilation of fourth ventricle
Enlarged posterior fossa with upward displacement of the tentorium
An angiographic finding key to the diagnosis prior to the advent of cross-sectional imaging in classic Dandy-Walker malformation
Torcular-lambdoid inversion
The elevation of the tentorium places the torcula herophili above the lambdoid sutures, an angiographic finding key to the diagnosis prior to the advent of cross-sectional imaging, termed “torcular–lambdoid inversion.”
T/F: Obstructive hydrocephalus is a common complication and is a part of the malformation itself
False
Obstructive hydrocephalus is a common complication but is not a part of the malformation itself
In the postnatal period the height of the vermis should be roughly equal to the distance between the ____ and ____
Midbrain tectum and obex
In dy–Walker variant, a hypoplastic vermis is often rotated counterclockwise such that the tegmento-vermian angle, formed by lines drawn along the brainstem and ventral vermis, is ____
> 18 degrees
It is an embryonic structure that perforates in the first trimester to form the foramen of Magendie and foramina of Luschka
Blake pouch
This is the only entity in the DANDY–WALKER CONTINUUM where the tegmento-vermian angle is normal
Mega cisterna magna
This is the only entity in the DANDY–WALKER CONTINUUM where the posterior fossa is large
Classic Dandy-Walker Malformation
Blake pouch remnant can be considered normal up to what AOG?
20 weeks AOG
When the perforation of Blake pouch is delayed or incomplete, it can result in a ____ causing upward displacement of an otherwise normally formed cerebellar vermis. The vermis is normal in size and morphology in this entity, but the tegmento-vermian angle is increased.
Blake pouch remnant or cyst
It is a result of delayed fenestration of Blake pouch; it is defined as isolated enlargement of the cisterna magna with a normal tegmento-vermian angle and is considered a normal variant.
Mega cisterna magna
Cut off to consider enlargement of cisterna magna
> 10 mm
It is heterogeneous group of disorders mostly resulting from mutations of genes encoding ciliary proteins. Clinically these patients are described to have episodes of irregular breathing during infancy (“panting” or “laughing” respirations) with oculomotor apraxia.
Give the classic neuroimaging findings (2) seen below and the diagnosis
- Vermian hypoplasia
- Molar tooth sign
Joubert Syndrome and Related Disorders (JSRD)
Molar tooth sign: thickening and elongation of the superior cerebellar peduncles resemble the root of an extracted molar tooth on axial MR images
It is the incomplete separation of the cerebellar hemispheres in association with partial or complete absence of the vermis. MR imaging can uniquely demonstrate the transversely oriented continuous folia, and the flattened fastigial recess caused by at least partial absence of the cerebellar vermis.
Rhombencephalosynapsis
It is the most severe manifestation of decreased cellular proliferation, in which there is nearcomplete absence of the sulci and gyri with marked microcephaly (
Microlissencephaly
It is a milder phenotype where the brain is smaller than normal, with a reduced number of simple-appearing gyri
Microcephaly with simplified gyral pattern
The most extreme manifestation of increased cellular proliferation is ____, a hamartomatous overgrowth of part or all of a cerebral hemisphere.
Hemimegalencephaly
A less dramatic and more localized increase in proliferation in association with abnormal cellular differentiation can result in ____, a leading cause of medically refractory epilepsy in children. These lesions can be very subtle on imaging, with focal cortical thickening, blurring of the gray–white matter junction, and a funnel-shaped white matter signal abnormality extending from the subcortical region toward the ventricle
Type II focal cortical dysplasia (FCDII)
It is the result of arrest of the radial migration of neurons from the germinal matrix along the walls of the ventricles to the developing cerebral cortex during the migrational phase.
Gray matter heterotopia
It is a genetically driven migrational arrest that typically appears as smooth symmetric bands of gray matter found between the ventricular surface and cerebral cortex. The overlying cortex is either normal or along the lissencephaly/pachygyria spectrum and nearly all affected patients are female
Band heterotopia
It is the result of arrested neuronal migration resulting in an abnormally thickened cortex and absence of the normal gyral–sulcal pattern.
Describe the sign/appearance, identify the pointed structure and give the diagnosis
Hour-glass appearance
Cell-sparse zone
Lissencephaly/Pachygyria
It results from abnormalities of late neuronal migration and cortical organization, causing an increased number of abnormally small gyri
Polymicrogyria
Most common location of polymicrogyria
Perisylvian
It is believed to reflect a prevention of neuronal migration from the germinal matrix outward, resulting in a transmantle cleft lined by dysplastic gray matter extending from the ependyma to the pial surface
Schizencephaly
Although neuronal migration continues to occur throughout gestation and beyond delivery, a majority occurs between ____.
12 and 24 weeks
Give the diagnosis and the artery that which was bilaterally obstructed to have resulted in this condition
Hyranencephaly
Internal carotid artery
What supplies the surviving brain the infants with hydranencephaly?
Posterior circulation and/or meningeal branches of the external carotid arteries
It is a distinct pattern of white matter injury that affects the developing brain, between 24 and 34 weeks of gestational age, caused by damage to oligodendrocyte precursor cells (preoligodendrocytes, oligodendrocyte progenitor cells [OPCs]).
It is a pattern of injury that is seen in many children diagnosed with cerebral palsy; symmetric loss of periventricular white matter surrounding the trigones of the lateral ventricles, with a characteristic angular morphology of the adjacent lateral ventricles as they expand into the vacated parenchyma
Periventricular leukomalacia
MR imaging will show punctate foci of abnormal hyperintensity in the periventricular white matter on T1WI
It represents a “watershed zone” of cerebral blood flow in the immature brain, with poor autoregulation
Periventricular white matter
This week AOG will determine whether or not gliosis shall be observed in PVL
34 weeks AOG
These are hereditary syndromes that are grouped together because they primarily affect structures of ectodermal origin, that is, the nervous system and skin.
Neurocutaneous disorders or phakomatoses
The most common of the phakomatoses
Neurofibromatosis type 1 (von Recklinghausen disease, NF-1)
Peripheral neurofibromatosis
It usually develops multiple cutaneous lesions (café au lait spots, axillary freckling, cutaneous neurofibromas, and Lisch nodules) and for this reason, this NF was termed peripheral neurofibromatosis
NF-1
Per1pheral NF
Which NF has its nerve sheath tumors the potential for malignant degeneration?
NF-1
Aka entral neurofibromatosis
NF-2
It is an autosomal dominant disorder, characterized by dysplastic tumor-like lesions in the brain, lungs, skin, kidneys, and heart
Tuberous sclerosis
It is a consequence of failure of development of venous structures draining cerebral cortex, eye, and skin. In the face this results in a cutaneous capillary malformation called a port-wine nevus.
Sturge–Weber syndrome (encephalotrigeminal angiomatosis)
Name: Red arrow, white arrow, arrowhead
Give the diagnosis
Red: subcortical tubers
White: subependymal nodules
Arrowhead: Subependymal giant cell astrocytoma or “subependymal giant cell astrocytoma (SEGA)
It is an autosomal dominant disorder consisting of retinal, cerebellar and spinal hemangioblastomas. Other features include renal cell carcinoma, pheochromocytoma, cysts in the kidneys, liver, and pancreas. It typically manifests in the second and third decades.
von Hippel– Lindau syndrome (CNS angiomatosis)
Considered benign vascular neoplasm with characteristic features of a well-circumscribed cystic lesion with an enhancing mural nodule. A helpful finding suggesting the diagnosis is a large blood vessel leading to the enhancing nodule
Hemangioblastoma
Rarely the neural tube will successfully separate from the cutaneous ectoderm and close but a defect in the skin will persist, with a tract that descends into the subcutaneous tissues or spinal canal called a ____
Diagnosis:
Dorsal dermal sinus
Diagnosis: Infected dorsal derma sinus
It is characterized by agenesis of a portion of the caudal spine usually in association with spinal cord, anorectal and/or genitourinary anomalies.
Caudal agenesis or caudal regression syndrome
Group 1 vs Group 2 caudal regression syndrome:
a. Low-lying tethered cord and may have an additional closed spinal dysraphism such as an intradural lipoma or lipomyelomeningocele.
b. Have a high (L1 or higher) blunted conus with separation of the anterior and posterior nerve roots in a “double-bundle” configuration.
a. Group 2
b. Group 1
Group 1: HIGH
Group 2: LOW
In a process called neurulation, the neural ectoderm folds inward and forms a tube, with the center of the tube becoming the ____ and the central canal of the spinal cord.
Ventricles
Open spinal dysraphisms, sometimes categorized as ____
Spina bifida aperta
This type of spina bifida aperta has its neural placode projecting beyond the plane of the back the malformation
Myelomeningocele
This type of spina bifida aperta has its neural placode laying flat relative to the rest of the back
Myelocele
This lesion forms when interspersed mesodermal tissue prevents the normal development of the posterior bony elements and differentiates into fat, which is contiguous with the subcutaneous fat and tethers the cord at the site of the malformation:
a. If the placode projects beyond the posterior laminar line
b. If the placode does not project beyond the posterior laminar line
Diagnosis:
a. Lipomyelomeningocele
b. Lipomyelocele
Diagnosis: Lipomyelocele
If the mesodermal tissue completely separates from the overlying mesoderm, the posterior elements of the bony canal can close, and the result is an ____
Intradural lipoma
The major abnormality in ____ is a focal dilation of the central canal that causes the cord to protrude through a defect in the dorsal elements. Unlike other closed (skin-covered) spinal dysraphisms, this can be associated with hindbrain herniation.
Myelocystocele
Skin-covered lesions, myelocystoceles can occur in either, and are called:
a. Lumbar or lumbosacral
b. Cervical or thoracic spine
Diagnosis:
a. Terminal myelocystocele
b. Nonterminal myelocystocele
Diagnosis: Nonterminal myelocystocele
It is thought that the development of the neural plate and subsequent infolding to form the neural tube is induced by the ____, a streak of cells situated between the ectoderm and endoderm.
Notochord
If the notochord is divided, two separate neural tubes may form, resulting in two hemicords, called ____
Diastematomyelia or split cord malformation (SCM)
Type 1 vs Type 2 SCM:
a. Each hemicord with their own dural sac
b. Single dural sac
Diagnosis:
a. Type 1 SCM
b. Type 2 SCM
Diagnosis: Type 1 SCM
It is a clinical diagnosis based upon the constellation of pain, gait abnormalities, sensory disturbances, and/or lower extremity weakness, in association with a structural abnormality of the distal cord that could be a cause of increased tension or restricted mobility of the conus medullaris.
Diagnosis:
Tethered cord syndrome
Diagnosis: Fatty Filum Terminale With Tethered Cord
It is the term used to describe a cystic cavity within the spinal cord, usually representing the dilated central canal
Diagnosis:
Syringomyelia or syrinx
Diagnosis: Syringomyelia
The normal central canal is frequently visible on MR imaging, and diameters of up to ____ are likely of no significance.
3 mm
Scoliosis is defined as any lateral spinal curvature ____.
> 10 degrees
Scoliosis:
a. Most frequent type, with female preponderance and typically presenting with a primary thoracolumbar curve convex to the right (dextroscoliosis).
b. Progression is most common in this type
a. Adolescent
b. Juvenile
