Radiology Flashcards
(197 cards)
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.