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ABR Neuroradiology study materials
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ABR Neuroradiology practice questions

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Question 1Brain

A 55-year-old man has a sudden severe headache. Noncontrast head CT shows hyperdensity in the basal cisterns. What is the most likely diagnosis?

  1. Acute subarachnoid hemorrhage Correct answer.
  2. Chronic subdural hematoma
  3. Cerebral infarction
  4. Epidural hematoma

Explanation

Fresh blood is hyperdense on noncontrast CT, and the basal cisterns are a classic location for aneurysmal subarachnoid hemorrhage. Chronic subdural hematomas are typically hypodense and lentiform over the convexity, and infarcts are hypodense.

Question 2Brain

Which imaging finding best distinguishes an epidural hematoma from a subdural hematoma on CT?

  1. Biconvex shape that does not cross suture lines Correct answer.
  2. Hyperdensity within the ventricles
  3. Crescentic shape that crosses suture lines
  4. Hypodensity in the white matter

Explanation

Epidural hematomas are arterial (often middle meningeal) and are confined by dural attachments at sutures, producing a biconvex/lentiform shape. Subdural hematomas are venous and spread freely under the dura, producing a crescentic shape that crosses sutures.

Question 3Brain

A patient with a suspected acute ischemic stroke has a normal noncontrast CT. Which sequence is most sensitive for detecting restricted diffusion within the first hours?

  1. T2-weighted imaging
  2. T1-weighted imaging
  3. Diffusion-weighted imaging Correct answer.
  4. Gradient-echo imaging

Explanation

Diffusion-weighted imaging detects cytotoxic edema within minutes of infarction, appearing as restricted diffusion with low apparent diffusion coefficient. T1 and T2 changes lag by hours, and gradient-echo is used for hemorrhage.

Question 4Brain

A patient presents with a thunderclap headache and a normal noncontrast head CT performed 10 hours after onset. What is the most appropriate next step to evaluate for subarachnoid hemorrhage?

  1. MRI of the cervical spine
  2. Carotid ultrasound
  3. Lumbar puncture for xanthochromia Correct answer.
  4. Repeat noncontrast CT in 48 hours

Explanation

Noncontrast CT sensitivity for subarachnoid hemorrhage declines with time from onset; when CT is negative and suspicion remains, lumbar puncture for xanthochromia is the standard next step. Repeat delayed CT, spine MRI, and carotid ultrasound do not address acute subarachnoid blood.

Question 5Brain

On MRI, a lesion is hyperintense on T2/FLAIR, hypointense on T1, and shows peripheral ring enhancement. Which feature most suggests a neoplastic rather than infectious ring-enhancing lesion?

  1. Restricted diffusion in the central cavity
  2. Thick irregular enhancing wall with nodularity Correct answer.
  3. Thin smooth enhancing wall
  4. Surrounding vasogenic edema alone

Explanation

Neoplastic ring enhancement typically shows a thick, irregular, nodular wall, whereas abscesses classically have a thin, smooth wall. Central restricted diffusion favors an abscess cavity, and edema alone is nonspecific.

Question 6Brain

A patient with neurofibromatosis type 2 is most likely to develop which intracranial tumor?

  1. Pleomorphic xanthoastrocytomas
  2. Bilateral vestibular schwannomas Correct answer.
  3. Subependymal giant cell astrocytomas
  4. Hemangioblastomas

Explanation

Neurofibromatosis type 2 is defined by bilateral vestibular schwannomas, often with meningiomas and ependymomas. Hemangioblastomas occur in von Hippel-Lindau disease, and subependymal giant cell astrocytomas occur in tuberous sclerosis.

Question 7Brain

A 3-day-old neonate has seizures. Ultrasound shows echogenic material in the lateral ventricles. What is the most likely cause?

  1. Germinal matrix hemorrhage Correct answer.
  2. Subdural empyema
  3. Cavernous malformation
  4. Meningioma

Explanation

Preterm and neonatal germinal matrix hemorrhage originates in the subependymal germinal matrix and can rupture into the ventricles, appearing echogenic on ultrasound. Empyema, meningioma, and cavernous malformation are not typical neonatal causes of intraventricular blood.

Question 8Brain

Which imaging modality is preferred for initial evaluation of a hemodynamically stable patient with suspected acute cervical spine injury after trauma?

  1. CT of the cervical spine Correct answer.
  2. Ultrasound of the neck
  3. Plain radiography of the cervical spine
  4. MRI of the cervical spine

Explanation

CT is the modality of choice for acute cervical spine trauma because of its high sensitivity for fractures and rapid acquisition. MRI is reserved for suspected ligamentous or cord injury, and plain films and ultrasound are less sensitive.

Question 9Brain

A patient has a pituitary macroadenoma with suprasellar extension compressing the optic chiasm. Which visual field defect is most expected?

  1. Homonymous hemianopia
  2. Bitemporal hemianopia Correct answer.
  3. Binasal hemianopia
  4. Central scotoma

Explanation

The optic chiasm contains crossing fibers from the nasal retina, which subserve the temporal visual fields. Compression from below produces a bitemporal hemianopia, often beginning superiorly.

Question 10Brain

Which finding on CT most strongly suggests a hyperacute middle cerebral artery occlusion?

  1. Encephalomalacia
  2. Hypodense lentiform nucleus
  3. Hyperdense MCA sign Correct answer.
  4. Sulcal effacement

Explanation

A hyperdense middle cerebral artery represents acute thrombus within the vessel and is an early sign of occlusion. Hypodense lentiform nucleus and sulcal effacement are later signs, and encephalomalacia reflects chronic injury.

Question 11Brain

A patient with a known lung carcinoma develops multiple ring-enhancing cerebral lesions at the gray-white junction. What is the most likely diagnosis?

  1. Brain metastases Correct answer.
  2. Progressive multifocal leukoencephalopathy
  3. Primary CNS lymphoma
  4. Herpes simplex encephalitis

Explanation

Multiple ring-enhancing lesions at the gray-white junction in a patient with a known primary malignancy are classic for hematogenous brain metastases. Primary CNS lymphoma usually shows homogeneous enhancement, and PML and herpes encephalitis have different patterns.

Question 12Brain

Which sequence best demonstrates acute hemorrhage as hypointense signal due to susceptibility effects?

  1. MR spectroscopy
  2. Gradient-echo or susceptibility-weighted imaging Correct answer.
  3. T1-weighted imaging
  4. Diffusion-weighted imaging

Explanation

Gradient-echo and susceptibility-weighted sequences are sensitive to the paramagnetic effects of blood breakdown products, appearing hypointense. T1, diffusion, and spectroscopy are not primary sequences for detecting hemorrhage.

Question 13Brain

A patient has a cystic lesion with a mural nodule and an enhancing nodule in the cerebellar hemisphere. Which diagnosis is most likely in an adult?

  1. Medulloblastoma
  2. Hemangioblastoma Correct answer.
  3. Pilocytic astrocytoma
  4. Ependymoma

Explanation

A cystic cerebellar mass with an enhancing mural nodule in an adult is classically a hemangioblastoma, often associated with von Hippel-Lindau disease. Medulloblastoma and ependymoma arise in the fourth ventricle, and pilocytic astrocytoma is more common in children.

Question 14Brain

Which imaging feature is most characteristic of an acute hypertensive intraparenchymal hemorrhage?

  1. Hypodensity in the basal ganglia on noncontrast CT
  2. Hyperdensity in the basal ganglia on noncontrast CT Correct answer.
  3. Restricted diffusion in the basal ganglia
  4. Enhancement of the basal ganglia on postcontrast CT

Explanation

Acute intraparenchymal hemorrhage appears hyperdense on noncontrast CT, and the basal ganglia are a classic location for hypertensive hemorrhage. Hypodensity, enhancement, and restricted diffusion describe ischemia or other processes rather than acute blood.

Question 15Brain

A patient with a suspected cerebral abscess has a ring-enhancing lesion. Which finding most supports an abscess over a necrotic tumor?

  1. Restricted diffusion within the central cavity Correct answer.
  2. Thick irregular nodular wall
  3. Multiple lesions at the gray-white junction
  4. Extensive surrounding edema

Explanation

Purulent material restricts diffusion, producing central high signal on DWI with low ADC in an abscess cavity. Thick irregular walls, extensive edema, and gray-white junction location are more suggestive of neoplasm.

Question 16Brain

Which structure is most commonly compressed by a posterior communicating artery aneurysm?

  1. Oculomotor nerve Correct answer.
  2. Optic nerve
  3. Facial nerve
  4. Trigeminal nerve

Explanation

Posterior communicating artery aneurysms classically compress the oculomotor nerve, producing a painful third nerve palsy with pupillary involvement. The optic, trigeminal, and facial nerves are not the typical targets.

Question 17Brain

A patient has a dural arteriovenous fistula with cortical venous drainage. What is the primary concern?

  1. Intracranial hemorrhage Correct answer.
  2. Hydrocephalus
  3. Optic neuritis
  4. Diabetes insipidus

Explanation

Cortical venous drainage in a dural AV fistula carries a high risk of venous hypertension and intracranial hemorrhage. Hydrocephalus, diabetes insipidus, and optic neuritis are not the primary concerns.

Question 18Brain

A patient has bilateral thalamic lesions. Which vascular territory is most likely involved?

  1. Artery of Percheron Correct answer.
  2. Posterior inferior cerebellar artery
  3. Superior cerebellar artery
  4. Anterior inferior cerebellar artery

Explanation

The artery of Percheron is a variant in which a single arterial trunk supplies both paramedian thalami, so occlusion causes bilateral thalamic infarction. The cerebellar arteries supply the posterior fossa, not the thalami.

Question 19Brain

Which imaging finding is most consistent with normal pressure hydrocephalus?

  1. Multiple periventricular calcifications
  2. Ventriculomegaly with relatively preserved cortical sulci at the vertex Correct answer.
  3. Asymmetric temporal horn enlargement
  4. Severe diffuse cortical atrophy

Explanation

Normal pressure hydrocephalus shows enlarged ventricles with tight high-convexity sulci, often with flow void enlargement or aqueductal flow. Diffuse atrophy produces prominent sulci, and asymmetric temporal horn enlargement suggests other processes.

Question 20Brain

A patient has a colloid cyst. Where is it typically located?

  1. Fourth ventricle
  2. Cerebellopontine angle
  3. Lateral ventricle atrium
  4. Anterior third ventricle at the foramen of Monro Correct answer.

Explanation

Colloid cysts arise at the anterior third ventricle near the foramen of Monro and can cause obstructive hydrocephalus. The fourth ventricle, lateral ventricle atrium, and cerebellopontine angle are not typical locations.

Question 21Brain

Which MRI finding best supports a diagnosis of multiple sclerosis in a young adult?

  1. Bilateral thalamic restricted diffusion
  2. Symmetric basal ganglia calcifications
  3. Diffuse cortical atrophy
  4. Ovoid periventricular T2 hyperintensities perpendicular to the ventricles Correct answer.

Explanation

MS plaques classically appear as ovoid periventricular lesions oriented perpendicular to the ventricles (Dawson fingers). Symmetric calcifications, bilateral thalamic restricted diffusion, and diffuse atrophy suggest other diagnoses.

Question 22Brain

A child has a posterior fossa mass arising from the cerebellar vermis with restricted diffusion and hydrocephalus. What is the most likely diagnosis?

  1. Pilocytic astrocytoma
  2. Medulloblastoma Correct answer.
  3. Epidermoid cyst
  4. Hemangioblastoma

Explanation

Medulloblastoma arises from the cerebellar vermis in children and shows restricted diffusion due to high cellularity, often causing obstructive hydrocephalus. Pilocytic astrocytoma is typically cystic with a nodule, and epidermoid cysts show CSF-like signal.

Question 23Brain

Which finding on CT is most concerning for an uncal herniation?

  1. Effacement of the basal cisterns with medial temporal lobe displacement Correct answer.
  2. Enlargement of the fourth ventricle
  3. Widening of the sylvian fissure
  4. Bilateral subdural hygromas

Explanation

Uncal herniation displaces the medial temporal lobe over the tentorial edge, effacing the basal cisterns and potentially compressing the brainstem. Ventricular enlargement, hygromas, and sylvian fissure widening do not indicate uncal herniation.

Question 24Brain

A patient has a cavernous sinus mass that encases the internal carotid artery. Which finding suggests a meningioma rather than a schwannoma?

  1. Bony remodeling of the petrous apex
  2. Dural tail sign Correct answer.
  3. Cystic degeneration
  4. Restricted diffusion

Explanation

A dural tail sign reflects dural attachment and favors meningioma. Cystic degeneration and bony remodeling are more typical of schwannoma, and restricted diffusion is nonspecific.

Question 25Brain

Which imaging modality is most appropriate for screening a patient with a strong family history of intracranial berry aneurysms?

  1. Skull radiography
  2. Noncontrast head CT
  3. CT angiography or MR angiography Correct answer.
  4. Carotid ultrasound

Explanation

CT angiography and MR angiography are noninvasive vascular studies used to screen for berry aneurysms. Noncontrast CT, skull radiography, and carotid ultrasound do not reliably depict intracranial aneurysms.

Question 26Brain

Which brain structure is most commonly affected by an acute ischemic infarct in the territory of the recurrent artery of Heubner?

  1. The dorsolateral thalamus and posterior limb of the internal capsule
  2. The medial temporal lobe and hippocampus
  3. The occipital cortex and splenium
  4. The ventrolateral head of the caudate nucleus and anterior limb of the internal capsule Correct answer.

Explanation

The recurrent artery of Heubner is a perforating branch of the anterior cerebral artery that supplies the ventrolateral caudate head, anterior putamen, and anterior limb of the internal capsule. Infarcts here produce contralateral face and arm weakness with dysarthria.

Question 27Brain

A patient with a dural-based extra-axial mass shows homogeneous enhancement and a broad dural base with a dural tail. Which additional feature most favors meningioma over a solitary fibrous tumor of the dura?

  1. Restricted diffusion on DWI
  2. Marked hypointensity on T2-weighted images
  3. Hyperostosis of the adjacent calvarium Correct answer.
  4. Intratumoral calcification on CT

Explanation

Hyperostosis of the overlying bone is a classic feature of meningioma reflecting tumor invasion of the diploe and osteoblastic reaction. Solitary fibrous tumors typically lack this bone change despite otherwise overlapping imaging features.

Question 28Brain

Which imaging finding is most characteristic of a developmental venous anomaly on contrast-enhanced MRI?

  1. A flow void within a dilated cortical vein without a collecting system
  2. A nidus of enlarged feeding arteries and early draining veins
  3. A caput medusae of medullary veins converging on a single draining vein Correct answer.
  4. Multiple punctate foci of susceptibility artifact in a linear distribution

Explanation

A developmental venous anomaly appears as a radial collection of medullary veins converging on a single central draining vein, often called a caput medusae. It is a venous variant with normal brain parenchyma between the vessels.

Question 29Brain

A patient with a suspected pituitary apoplexy presents with sudden headache and visual loss. Which MRI finding most directly confirms hemorrhage within the adenoma?

  1. Diffuse homogeneous enhancement of the mass after contrast
  2. Hypointense signal on T2-weighted imaging with a fluid level
  3. Enlargement of the cavernous sinus bilaterally
  4. Hyperintense signal on unenhanced T1-weighted imaging within the sellar mass Correct answer.

Explanation

Subacute hemorrhage contains methemoglobin, which is intrinsically hyperintense on unenhanced T1-weighted images. This finding within a sellar mass supports apoplexy and helps distinguish hemorrhage from simple cystic degeneration.

Question 30Brain

Which pattern of cerebral involvement is most typical of adult-onset adrenoleukodystrophy?

  1. Symmetric basal ganglia calcification with thalamic sparing
  2. Bilateral frontal periventricular lesions perpendicular to the ventricles
  3. Unilateral temporal lobe edema with cortical ribboning
  4. Symmetric parieto-occipital white matter demyelination with splenium involvement Correct answer.

Explanation

Adult cerebral adrenoleukodystrophy characteristically involves the parieto-occipital white matter and splenium with contiguous spread, often with an advancing edge of enhancement. Frontal-predominant involvement is more typical of the childhood cerebral form.

Question 31Brain

A patient has a cystic-appearing lesion in the periventricular white matter that follows CSF signal on all sequences and shows no enhancement or restricted diffusion. Which diagnosis is most likely?

  1. Central neurocytoma
  2. Enlarged perivascular space Correct answer.
  3. Demyelinating plaque
  4. Pilocytic astrocytoma

Explanation

Enlarged perivascular spaces follow CSF signal on all sequences, do not enhance, and do not restrict diffusion. They are common incidental findings in the basal ganglia and periventricular white matter.

Question 32Brain

Which imaging feature best distinguishes a glioblastoma from a solitary metastasis at the gray-white junction?

  1. Surrounding vasogenic edema
  2. Mass effect with midline shift
  3. Contiguous spread across the corpus callosum Correct answer.
  4. Ring enhancement around a necrotic center

Explanation

Glioblastoma is an infiltrating glial tumor that frequently spreads along white matter tracts, including across the corpus callosum, producing a butterfly pattern. Metastases are hematogenous and tend to be multifocal but do not typically cross the midline through commissural fibers.

Question 33Brain

Which finding on MRI is most suggestive of a ruptured intracranial dermoid cyst?

  1. A fluid-fluid level within a suprasellar mass
  2. Peripheral rim enhancement of a cystic lesion
  3. Multiple droplets of fat signal in the subarachnoid spaces Correct answer.
  4. A calcified mural nodule with surrounding edema

Explanation

Rupture of a dermoid cyst releases lipid contents into the subarachnoid space, producing scattered fat-signal droplets that are bright on T1-weighted images. This can cause chemical meningitis.

Question 34Brain

Which imaging finding is most characteristic of central nervous system involvement in neurofibromatosis type 1?

  1. Multiple meningiomas
  2. Ependymomas of the spinal cord
  3. Bilateral vestibular schwannomas
  4. Bilateral optic pathway gliomas Correct answer.

Explanation

Neurofibromatosis type 1 is associated with optic pathway gliomas, particularly in children, along with focal areas of signal intensity in the basal ganglia and brainstem. Bilateral vestibular schwannomas are the hallmark of neurofibromatosis type 2.

Question 35Brain

A patient presents with progressive cognitive decline and gait disturbance. MRI shows ventriculomegaly with tight high-convexity sulci and enlarged Sylvian fissures. Which diagnosis is most likely?

  1. Normal pressure hydrocephalus Correct answer.
  2. Obstructive hydrocephalus from a third ventricular mass
  3. Alzheimer disease
  4. Ex vacuo ventriculomegaly from atrophy

Explanation

Disproportionately enlarged subarachnoid space hydrocephalus is a pattern of normal pressure hydrocephalus characterized by ventriculomegaly, tight high-convexity sulci, and enlarged Sylvian fissures. The combination with gait disturbance and cognitive decline supports the diagnosis.

Question 36Brain

Which sequence is most sensitive for detecting cortical hyperintensity in a patient with suspected herpes simplex encephalitis?

  1. T1-weighted imaging
  2. Time-of-flight MR angiography
  3. FLAIR Correct answer.
  4. Gradient-recalled echo

Explanation

FLAIR suppresses CSF signal and increases conspicuity of cortical and subcortical edema, making it sensitive for the cortical hyperintensity of herpes simplex encephalitis. The medial temporal lobes and insula are typically involved.

Question 37Brain

A patient has a lateral ventricular mass with a broad attachment to the septum pellucidum and calcification. Which diagnosis is most likely?

  1. Choroid plexus papilloma
  2. Central neurocytoma Correct answer.
  3. Subependymoma
  4. Ependymoma

Explanation

Central neurocytoma typically arises from the septum pellucidum or ventricular wall in young adults and frequently calcifies. It appears as a lobulated intraventricular mass with moderate enhancement.

Question 38Brain

Which finding on MRI is most consistent with a diagnosis of superficial siderosis of the central nervous system?

  1. Symmetric T2 hyperintensity of the basal ganglia
  2. Dilation of the perivascular spaces in the centrum semiovale
  3. Linear hypointensity along the surfaces of the brainstem and cerebellum on susceptibility-weighted imaging Correct answer.
  4. Enhancement of the leptomeninges over the convexities

Explanation

Superficial siderosis results from chronic subarachnoid hemorrhage with hemosiderin deposition along the pial surfaces. Susceptibility-sensitive sequences show linear hypointensity outlining the brainstem, cerebellum, and cranial nerves.

Question 39Brain

A patient with a known primary malignancy has a single enhancing brain lesion. Which feature most favors metastasis over a primary brain tumor?

  1. Involvement of the corpus callosum with a butterfly pattern
  2. Location at the gray-white junction with a small enhancing nodule and extensive edema Correct answer.
  3. Diffuse infiltration without a discrete enhancing component
  4. Cortical ribbon thickening with gyral enhancement

Explanation

Metastases commonly lodge at the gray-white junction where vessel caliber narrows, producing a small enhancing nodule with disproportionate vasogenic edema. The multiplicity and junctional location reflect hematogenous spread.

Question 40Brain

Which imaging feature is most characteristic of a pituitary microadenoma on dynamic contrast-enhanced MRI?

  1. Diffuse homogeneous enlargement of the gland
  2. A cystic lesion with a fluid level
  3. A hyperenhancing mass with dural tail
  4. A focal hypoenhancing lesion within the normally enhancing gland Correct answer.

Explanation

Pituitary microadenomas typically enhance more slowly than normal pituitary tissue, appearing as a focal hypoenhancing lesion on early dynamic postcontrast images. The normal gland enhances avidly and can mask a small adenoma on delayed images.

Question 41Brain

Which pattern of injury is most typical of posterior reversible encephalopathy syndrome?

  1. Bilateral subcortical vasogenic edema in the parieto-occipital regions Correct answer.
  2. Bilateral thalamic restricted diffusion with hemorrhage
  3. Bilateral symmetric restricted diffusion in the basal ganglia
  4. Unilateral cortical hyperintensity in the middle cerebral artery territory

Explanation

Posterior reversible encephalopathy syndrome classically produces bilateral, relatively symmetric vasogenic edema in the parieto-occipital subcortical white matter. The edema typically does not restrict diffusion unless infarction has occurred.

Question 42Brain

A patient has a mass in the pineal region with a cystic component, calcification, and marked enhancement. Which diagnosis is most likely in a young adult?

  1. Germinoma
  2. Pineal cyst
  3. Pineocytoma Correct answer.
  4. Pineoblastoma

Explanation

Pineocytoma is a well-differentiated pineal parenchymal tumor that typically occurs in adults and shows a cystic, calcified, enhancing mass. Pineoblastoma is more aggressive and occurs in children, while germinoma tends to be homogeneous and highly enhancing.

Question 43Brain

Which imaging finding is most suggestive of a cerebral amyloid angiopathy-related hemorrhage?

  1. Cerebellar hemorrhage with a fluid level
  2. Subdural hematoma with midline shift
  3. Deep gray matter hemorrhage with intraventricular extension
  4. Lobar hemorrhage with multiple peripheral microbleeds on susceptibility-weighted imaging Correct answer.

Explanation

Cerebral amyloid angiopathy involves cortical and leptomeningeal vessels, producing lobar hemorrhages and peripheral cortical-subcortical microbleeds. Deep gray matter hemorrhages are more typical of hypertensive small vessel disease.

Question 44Brain

Which finding on CT best supports a diagnosis of an acute subdural hematoma rather than an epidural hematoma?

  1. A collection with a fluid-fluid level
  2. A collection associated with a skull fracture
  3. A biconvex collection limited by suture lines
  4. A crescentic collection that crosses suture lines Correct answer.

Explanation

Subdural hematomas arise from bridging veins and spread freely in the subdural space, producing a crescentic collection that crosses suture lines. Epidural hematomas are bounded by skull sutures and appear biconvex.

Question 45Brain

A patient has a spinal dural arteriovenous fistula. Which brain MRI finding would most suggest intracranial venous congestion?

  1. Bilateral hippocampal atrophy
  2. Diffuse T2 hyperintensity of the brainstem and cerebellum with prominent medullary veins Correct answer.
  3. Hyperintensity of the middle cerebellar peduncles only
  4. Enhancement of the optic nerves

Explanation

Spinal dural arteriovenous fistulas with venous congestion can propagate to intracranial venous drainage, producing brainstem and cerebellar edema with engorged medullary veins. This reflects venous hypertensive encephalopathy.

Question 46Brain

Which finding is most characteristic of Wernicke encephalopathy on MRI?

  1. Bilateral occipital cortical restricted diffusion
  2. Symmetric T2 hyperintensity of the globus pallidus
  3. Symmetric T2 hyperintensity of the medial thalami and periaqueductal gray Correct answer.
  4. Unilateral temporal lobe hyperintensity

Explanation

Wernicke encephalopathy involves the medial thalami, periaqueductal gray, mammillary bodies, and tectal plate, producing symmetric T2 hyperintensity. The distribution reflects regions with high thiamine-dependent metabolism.

Question 47Brain

Which finding on MRI best distinguishes a vestibular schwannoma from a meningioma in the cerebellopontine angle?

  1. Extension into the internal auditory canal with widening of the porus acusticus Correct answer.
  2. Homogeneous enhancement
  3. A broad dural base with a dural tail
  4. Calcification within the mass

Explanation

Vestibular schwannomas arise from the vestibular nerve and characteristically extend into the internal auditory canal, widening the porus acusticus. Meningiomas are dural-based and typically do not enlarge the canal.

Question 48Brain

A patient with a suspected cerebral abscess has a ring-enhancing lesion. Which finding most strongly supports abscess over a necrotic tumor?

  1. An irregular thick enhancing rim with nodularity
  2. Enhancement of the adjacent leptomeninges only
  3. A thin smooth enhancing rim with restricted diffusion in the central cavity Correct answer.
  4. A central cavity with high apparent diffusion coefficient values

Explanation

Abscess cavities contain viscous pus that restricts diffusion, appearing bright on DWI and dark on ADC maps. The enhancing rim is typically thin and smooth compared with the irregular rim of a necrotic tumor.

Question 49Brain

Which imaging feature is most characteristic of a colloid cyst on MRI?

  1. A calcified mass in the pineal region
  2. A round lesion at the foramen of Monro that is hyperintense on T1-weighted imaging Correct answer.
  3. A cystic lesion in the cerebellopontine angle
  4. A lobulated mass in the atrium of the lateral ventricle

Explanation

Colloid cysts arise at the anterior third ventricle near the foramen of Monro and often show intrinsic T1 hyperintensity from mucinous contents. They can obstruct CSF flow and cause hydrocephalus.

Question 50Brain

Which finding on MRI is most consistent with a diagnosis of a cerebral cavernous malformation?

  1. A homogeneous enhancing mass with dural tail
  2. A caput medusae of medullary veins
  3. A nidus of flow voids with enlarged feeding arteries
  4. A popcorn-like lesion with a complete hemosiderin rim on susceptibility-weighted imaging Correct answer.

Explanation

Cavernous malformations appear as well-circumscribed lesions with a popcorn-like core and a complete hemosiderin rim, best seen on susceptibility-sensitive sequences. They are angiographically occult and do not show arterial flow voids.