Naveed Ahmad, MD
To comprehensively cover the full scope of stroke and cerebrovascular neuroimaging at an expert level, the following structured master bank provides 100 multiple-choice questions spanning 10 core subtopics (10 questions per subtopic). Each question includes high-yield key concepts, standard board-style options, correct answers, and expert neuroradiological explanations.
Category 1: Carotid Artery Plaque & Vulnerable Plaque Imaging
- Key Concepts: Evaluating carotid atherosclerosis requires going beyond luminal stenosis to identify high-risk (vulnerable) plaque features: intraplaque hemorrhage (IPH), a lipid-rich necrotic core (LRNC), and a thin or ruptured fibrous cap. High-resolution vessel-wall MRI (such as 3D T1 MPRAGE or black-blood sequences) is the diagnostic standard for characterizing these components.
- Which MRI sequence is most specific for identifying intraplaque hemorrhage (IPH) within a carotid atherosclerotic plaque?
- A) Time-of-Flight (TOF) MRA
- B) 3D T1-weighted variable-flip-angle fast spin-echo (e.g., MPRAGE)
- C) T2-weighted turbo spin-echo
- D) Phase-contrast MRA
- Answer: B | Explanation: MPRAGE and other T1-weighted black-blood techniques provide high T1 shortening sensitivity to methemoglobin, reliably signaling IPH.
- What histopathological feature of a carotid plaque is most strongly associated with subsequent ipsilateral ischemic stroke?
- A) Superficial calcified plates
- B) Thick, intact collagenous fibrous cap
- C) Thin or ruptured fibrous cap overlying a large lipid-rich necrotic core
- D) Luminal narrowing measuring exactly 30%
- Answer: C | Explanation: A thin or ruptured fibrous cap covering an unstable lipid-rich necrotic core with active inflammation and IPH is the hallmark of a vulnerable plaque.
- In the NASCET method of measuring internal carotid artery (ICA) stenosis, what is used as the denominator?
- A) The diameter of the stenotic lumen
- B) The estimated normal bulb diameter
- C) The diameter of the distal normal cervical ICA beyond the stenosis
- D) The common carotid artery diameter
- Answer: C | Explanation: NASCET compares the minimal residual luminal diameter to the normal distal cervical ICA lumen.
- What is the primary advantage of high-resolution vessel wall MRI over conventional ultrasound in carotid evaluation?
- A) Lower acquisition cost
- B) Direct visualization of plaque composition (lipid core, IPH, cap status)
- C) Real-time hemodynamic flow velocity measurement
- D) Elimination of patient motion artifact
- Answer: B | Explanation: Vessel wall MRI directly characterizes tissue composition, whereas ultrasound primarily assesses echogenicity and hemodynamics.
- Which carotid plaque component appears hyperintense on T2-weighted MRI sequences due to its high water content?
- A) Mature calcium deposits
- B) Fresh intraplaque hemorrhage
- C) Lipid-rich necrotic core components
- D) Dense fibrous tissue cap
- Answer: C | Explanation: Lipid pools and edema within the necrotic core prolong T2 relaxation times, yielding high signal on T2-weighted black-blood MRI.
- On Time-of-Flight (TOF) MRA, what artifact can sometimes mimic an eccentric thrombus or plaque ulceration in the carotid bulb?
- A) Motion ghosting from internal jugular veins
- B) Phase mapping from swallowing
- C) Signal saturation effects within slow-flowing or swirling laminar blood flow
- D) Susceptibility dropout from dental amalgam
- Answer: C | Explanation: Complex flow patterns and in-plane saturation in the bulb can lead to signal loss on TOF MRA, mimicking stenosis or plaque.
- Which ultrasound parameter is most reliable for diagnosing greater than 70% ICA stenosis?
- A) Peak systolic velocity (PSV) > 230 cm/s and end-diastolic velocity (EDV) > 100 cm/s
- B) PSV < 100 cm/s
- C) Absence of spectral broadening
- D) Common carotid velocity ratio of 1.0
- Answer: A | Explanation: High Doppler velocities (PSV > 230 cm/s and high EDV) correlate with severe (70-99%) luminal stenosis.
- What is the significance of superficial ulceration identified on cross-sectional CTA of a carotid plaque?
- A) It indicates a completely stable, calcified lesion.
- B) It represents a high-risk embolic source prone to platelet aggregation and thromboembolism.
- C) It is a benign anatomical variant of the carotid bulb.
- D) It reflects artifactual contrast streaming.
- Answer: B | Explanation: Plaque ulceration breaches the endothelial lining, exposing thrombogenic core materials directly to flowing blood.
- Why is contrast-enhanced MRA (CE-MRA) often superior to TOF MRA for evaluating carotid bifurcation disease?
- A) CE-MRA is independent of flow direction and less prone to in-plane saturation artifacts.
- B) CE-MRA does not require intravenous lines.
- C) CE-MRA provides superior spatial resolution of individual plaque layers.
- D) CE-MRA avoids the use of gadolinium agents.
- Answer: A | Explanation: CE-MRA relies on T1 shortening from the contrast bolus rather than flow-related enhancement, eliminating saturation dropouts.
- What is the typical imaging appearance of an organized carotid web (Caucasian focal arteriopathy)?
- A) Long-segment tapering smooth stenosis of the common carotid artery
- B) A shelf-like filling defect arising from the posterior wall of the internal carotid artery bulb
- C) Circumferential calcified ring stenosis
- D) Bilateral diffuse aneurysmal dilatation
- Answer: B | Explanation: A carotid web is a shelf-like filling defect in the proximal ICA bulb, increasingly recognized as a cause of cryptogenic stroke in young patients.
Category 2: ASPECTS and Acute Neuroimaging Scores
- Key Concepts: Semi-quantitative scoring systems simplify complex parenchymal evaluation on non-contrast CT. The Alberta Stroke Program Early CT Score (ASPECTS) divides the middle cerebral artery territory into 10 distinct regions to quantify early ischemic changes and guide thrombolysis or thrombectomy eligibility.
- How many total regional areas are evaluated when calculating the standard ASPECTS score on a non-contrast CT?
- A) 6 regions
- B) 8 regions
- C) 10 regions
- D) 12 regions
- Answer: C | Explanation: ASPECTS divides the MCA territory into 10 regions (6 cortical M1-M6, and 4 subcortical: caudate, lentiform, internal capsule, insular cortex).
- What does an ASPECTS score of 10 indicate on a baseline non-contrast head CT?
- A) Extensive, irreversible hemispheric infarction
- B) A completely normal scan with no signs of early ischemia
- C) Moderate ischemia involving exactly half of the MCA territory
- D) Severe subarachnoid hemorrhage
- Answer: B | Explanation: A score of 10 represents a completely normal baseline non-contrast CT scan without hypoattenuation or swelling.
- In the ASPECTS grading system, what specific finding within a defined region triggers the deduction of 1 point?
- A) Hyperdense intravascular thrombus
- B) Focal microbleed
- C) Hypoattenuation and loss of normal gray-white matter differentiation
- D) Cortical laminar calcification
- Answer: C | Explanation: Points are subtracted for early ischemic signs, specifically parenchymal hypoattenuation and blurring of the gray-white interface.
- What clinical limitation is commonly associated with using low ASPECTS scores (e.g., $\less 6$) for patient selection?
- A) It guarantees 100% favorable clinical outcomes.
- B) It correlates with a larger established infarct core and higher risk of hemorrhagic transformation after reperfusion.
- C) It only applies to posterior circulation strokes.
- D) It completely replaces perfusion imaging requirements.
- Answer: B | Explanation: Low ASPECTS scores denote large established ischemic cores, which carry a higher risk of futile recanalization and symptomatic hemorrhage.
- How is the posterior circulation evaluated using a modified adaptation of the ASPECTS scoring system?
- A) pc-ASPECTS, which evaluates the brainstem, cerebellum, and posterior cerebral artery (PCA) territories out of 10 points.
- B) By measuring the diameter of the basilar artery.
- C) By counting the number of pontine strokes.
- D) Posterior circulation cannot be scored semi-quantitatively.
- Answer: A | Explanation: Posterior circulation ASPECTS (pc-ASPECTS) assigns 10 points across the midbrain, pons, cerebellum, and PCA territories.
- What is the primary anatomical boundary separating the M1, M2, and M3 regions in the ASPECTS grid?
- A) The central sulcus
- B) The Sylvian fissure and insular cortex landmarks (M1-M6 cortical tiers)
- C) The tentorium cerebelli
- D) The corpus callosum
- Answer: B | Explanation: Cortical ASPECTS regions M1 through M6 correspond to specific anterior, middle, and posterior MCA branch territories demarcated by the insular ribbon and Sylvian fissure.
- Which non-contrast CT finding is evaluated alongside ASPECTS to rule out hemorrhage before thrombolysis?
- A) Skull fracture lines
- B) Pineal gland calcification
- C) Hyperdense middle cerebral artery sign and sulcal effacement
- D) Choroid plexus calcification
- Answer: C | Explanation: Sulcal effacement reflects early cytotoxic edema, while the hyperdense MCA sign indicates acute intraluminal thrombus.
- Why might early ischemic changes be subtle or entirely missed on a baseline non-contrast CT within the first hour of stroke onset?
- A) Intracellular water shift has not yet reached a threshold density change detectable by human eye.
- B) CT beam-hardening artifacts obscure the entire brain.
- C) Blood pressure is too high.
- D) The patient’s skull blocks X-ray photons.
- Answer: A | Explanation: Subtle cytotoxic edema in hyperacute stroke ($<1$ hour) produces minimal X-ray attenuation changes, leading to low initial CT sensitivity.
- What score threshold is frequently utilized in clinical trials as an upper cutoff for selecting patients for mechanical thrombectomy without advanced perfusion imaging?
- A) ASPECTS $\ge 6$
- B) ASPECTS $\less 2$
- C) ASPECTS equal to 0
- D) ASPECTS exactly 5
- Answer: A | Explanation: Traditionally, an ASPECTS of 6 or greater signifies a sufficiently small core to justify standard thrombectomy without mandatory perfusion imaging.
- What is a recognized inter-observer limitation of manual ASPECTS scoring on non-contrast CT?
- A) Perfect 100% agreement among all readers regardless of experience
- B) Variability among readers, particularly in subtle or early ischemic changes and varying window/level settings
- C) Inability to view images in axial planes
- D) Requirement for intravenous contrast injection
- Answer: B | Explanation: Subjectivity in windowing and recognizing subtle gray-white blurring leads to moderate inter-observer variability in manual ASPECTS.
Category 3: Stroke with Unclear Onset Times & DWI-FLAIR Mismatch
- Key Concepts: For patients with unknown symptom onset (e.g., wake-up strokes), identifying whether tissue is salvageable relies on physiological imaging. Acute ischemic lesions are visible on diffusion-weighted imaging (DWI) within minutes, but take several hours to become hyperintense on fluid-attenuated inversion recovery (FLAIR) due to free water accumulation.
- What pathophysiological change accounts for FLAIR hyperintensity developing in an acute ischemic stroke over time?
- A) Immediate extravasation of whole blood
- B) Accumulation of vasogenic edema and extracellular free water altering T1 and T2 relaxation times over hours
- C) Rapid calcification of necrotic neurons
- D) Immediate breakdown of skull bones
- Answer: B | Explanation: As ischemia evolves past several hours, vasogenic edema and structural matrix breakdown increase free water, causing high signal on FLAIR.
- What does a positive DWI lesion with a completely negative FLAIR signal (DWI-FLAIR mismatch) indicate regarding stroke timing?
- A) The stroke occurred more than 24 hours ago.
- B) The stroke occurred recently, typically within the 4.5-hour therapeutic window.
- C) The lesion is completely chronic and inactive.
- D) The patient is experiencing a migraine aura.
- Answer: B | Explanation: The absence of FLAIR hyperintensity combined with bright DWI strongly suggests the ischemic event began less than 4.5 hours ago.
- Which major clinical trial validated the use of MRI-guided thrombolysis (DWI-FLAIR mismatch) in wake-up stroke patients?
- A) WAKE-UP trial
- B) DAWN trial
- C) DEFUSE 3 trial
- D) MR CLEAN trial
- Answer: A | Explanation: The WAKE-UP trial demonstrated that intravenous alteplase guided by DWI-FLAIR mismatch improved favorable functional outcomes in unknown-onset stroke.
- How does apparent diffusion coefficient (ADC) behave in the hyperacute phase of ischemic stroke?
- A) ADC increases markedly (hyperintense).
- B) ADC decreases markedly (hypointense/dark).
- C) ADC remains completely unchanged from normal brain tissue.
- D) ADC alternates randomly between bright and dark.
- Answer: B | Explanation: Restricted water mobility from cytotoxic edema restricts diffusion, yielding low (dark) signal on ADC maps.
- Why is the ADC map essential to review alongside high b-value DWI?
- A) To check for patient motion artifacts
- B) To differentiate true restricted diffusion (cytotoxic edema) from T2 shine-through effects
- C) To calculate exact cerebral blood volume
- D) To visualize the scalp vasculature
- Answer: B | Explanation: T2 shine-through causes high signal on DWI without true restriction; ADC confirms true restriction by showing corresponding hypointensity.
- What is “pseudo-normalization” of ADC in subacute stroke?
- A) ADC values returning toward baseline as vasogenic edema develops, potentially masking residual infarct core on ADC alone
- B) Complete recovery of normal brain function within 5 minutes
- C) Permanent disappearance of all imaging findings
- D) Conversion of ischemia into a subdural hematoma
- Answer: A | Explanation: Around 7 to 10 days post-stroke, increasing extracellular water causes ADC values to normalize, hiding the core on ADC maps while DWI remains abnormal.
- In unknown-onset stroke, what is the role of advanced CT perfusion when MRI is contraindicated or unavailable?
- A) It provides no useful clinical information.
- B) It assesses the penumbra-to-core mismatch to determine eligibility for extended-window thrombectomy.
- C) It measures intracranial pressure directly.
- D) It replaces the need for catheter angiography entirely.
- Answer: B | Explanation: Perfusion CT identifies salvageable tissue mismatch similarly to MR protocols when MRI cannot be performed.
- What is the typical time frame for an ischemic lesion to transition from FLAIR-negative to FLAIR-positive?
- A) Exactly 15 minutes
- B) Approximately 3 to 4.5 hours after symptom onset
- C) Exactly 7 days
- D) 3 weeks
- Answer: B | Explanation: Histopathological and clinical studies show FLAIR hyperintensity usually emerges between 3 and 4.5 hours from ischemia onset.
- What potential pitfall can cause a chronic lacunar infarct to appear bright on DWI?
- A) T2 shine-through effect
- B) Acute hemorrhage within the old cyst
- C) Contrast enhancement
- D) Patient head rotation
- Answer: A | Explanation: High T2 signal in a chronic CSF-filled lacunar cyst can bleed through into high b-value DWI images (T2 shine-through), easily debunked by examining ADC.
- Which imaging sign on gradient echo (GRE) or SWI suggests a stroke is due to underlying cerebral amyloid angiopathy rather than thromboembolism?
- A) Single deep ganglionic hemorrhage
- B) Multiple strictly lobar microbleeds and superficial siderosis
- C) Complete absence of intracranial vessels
- D) Massive dural venous sinus thrombosis
- Answer: B | Explanation: Lobar microbleeds and cortical superficial siderosis on susceptibility-weighted imaging are classic signatures of cerebral amyloid angiopathy.
Category 4: MR Diffusion Imaging & Pathophysiology of Ischemia
- Key Concepts: Diffusion-weighted imaging measures the random (Brownian) motion of water molecules. Ischemia halts cellular ATP production, shutting down Na+/K+-ATPase pumps and causing rapid cytotoxic edema (intracellular water shift), restricting diffusion and producing high signal intensity on DWI.
- What is the cellular consequence of cerebral ATP depletion during acute ischemia regarding ion pumps?
- A) Upregulation of ATP production
- B) Failure of Na+/K+-ATPase pumps, leading to intracellular sodium and water accumulation
- C) Enhanced potassium reuptake into neurons
- D) Complete stabilization of neuronal cell membranes
- Answer: B | Explanation: Energy failure disables Na+/K+-ATPase pumps, causing intracellular influx of sodium and water (cytotoxic edema).
- What physical principle governs the signal intensity observed on high b-value DWI sequences?
- A) Phase-contrast velocity encoding
- B) The degree of restricted or hindered random Brownian motion of water molecules
- C) Magnetic susceptibility differences of iron
- D) Longitudinal relaxation time (T1) recovery rates
- Answer: B | Explanation: DWI signal attenuation is proportional to the diffusion rate of water; restricted diffusion yields high signal.
- How does vasogenic edema differ from cytotoxic edema in terms of water compartmentalization?
- A) Vasogenic edema involves intracellular fluid accumulation; cytotoxic edema involves extracellular fluid.
- B) Vasogenic edema involves breakdown of the blood-brain barrier with extracellular fluid accumulation; cytotoxic edema involves intracellular swelling.
- C) Both types of edema occur exclusively within CSF spaces.
- D) Neither type affects water movement.
- Answer: B | Explanation: Vasogenic edema breaks down tight junctions, expanding extracellular space. Cytotoxic edema swells cells, shrinking extracellular space.
- What is the approximate time window after arterial occlusion for DWI to become abnormal?
- A) 24 hours
- B) Within minutes (typically 2 to 15 minutes)
- C) 3 days
- D) 2 weeks
- Answer: B | Explanation: Cytotoxic edema begins almost instantaneously upon severe ischemia, making DWI abnormal within minutes of vessel occlusion.
- What is the definition of the “ischemic penumbra”?
- A) The irreversibly destroyed necrotic core
- B) Structurally and electrically dysfunctional but metabolically viable tissue surrounding the core that can recover if reperfused promptly
- C) Normal brain tissue with elevated blood flow
- D) The subarachnoid hemorrhage space
- Answer: B | Explanation: The penumbra is critically hypoperfused salvageable tissue at risk of infarction if recanalization is delayed.
- Which MR parameter maps the true diffusion coefficient without T2 contribution?
- A) T2-weighted turbo spin-echo
- B) Apparent Diffusion Coefficient (ADC) map
- C) Time-of-Flight MRA
- D) Fluid-attenuated inversion recovery (FLAIR)
- Answer: B | Explanation: Calculating ADC from multiple b-values mathematically removes T2 shine-through effects.
- What is “reversal of diffusion lesion” in acute stroke?
- A) A common everyday occurrence in all stroke patients
- B) A rare phenomenon where areas showing initial restricted diffusion completely normalize following immediate recanalization, though most DWI core lesions represent irreversible injury.
- C) Spontaneous complete regeneration of the skull bone
- D) The conversion of ischemic stroke into a meningioma
- Answer: B | Explanation: While rare in humans, prompt reperfusion can occasionally salvage tissue exhibiting mild early restricted diffusion, though established core is generally irreversible.
- Why does myelination status affect diffusion metrics in neonatal versus adult stroke?
- A) Neonatal brains have higher baseline water content and unmyelinated tracts with different baseline diffusion anisotropy.
- B) Neonates cannot undergo MRI.
- C) Myelin blocks all radiofrequency pulses.
- D) Adults do not have white matter tracts.
- Answer: A | Explanation: Unmyelinated infant brains have higher water diffusion rates, requiring adjusted interpretation compared to adult myelinated white matter.
- What does Fractional Anisotropy (FA) measure on Diffusion Tensor Imaging (DTI)?
- A) The absolute blood volume in milliliters
- B) The directional preference (anisotropy) of water diffusion within white matter fiber tracts
- C) The concentration of gadolinium contrast
- D) The degree of skull base pneumatization
- Answer: B | Explanation: FA quantifies how directionally restricted water diffusion is, reflecting white matter tract integrity.
- How does wallerian degeneration manifest on DTI and conventional MRI weeks to months after a large cortical infarct?
- A) Increased fractional anisotropy and preserved fiber density
- B) Loss of fiber tract integrity, decreased FA, and high T2/FLAIR signal along corticospinal tracts downstream
- C) Immediate regeneration of severed axons
- D) Hypertrophic expansion of the affected motor strip
- Answer: B | Explanation: Wallerian degeneration causes anterograde axonal breakdown, showing decreased FA and chronic tract atrophy downstream from the infarct.
Category 5: Transient Ischemic Attack (TIA) & Risk Stratification
- Key Concepts: Transient Ischemic Attack (TIA) is defined as a brief episode of neurological dysfunction caused by focal brain, spinal cord, or retinal ischemia without acute infarction. Because TIA carries a high imminent risk of major stroke, rapid diagnosis, etiology determination, and short-term risk stratification (ABCD2/ABCD3-I scores) are vital.
- What is the modern tissue-based definition of a TIA compared to traditional time-based definitions?
- A) Symptoms lasting longer than 24 hours
- B) Transient symptoms without acute infarction on neuroimaging versus traditional $>24$ hour duration cutoffs
- C) Permanent neurological deficit confirmed on CT
- D) Recurrent seizures without vascular risk factors
- Answer: B | Explanation: Modern consensus defines TIA based on the absence of acute ischemic infarction on imaging, moving away from arbitrary 24-hour symptom duration rules.
- What clinical variables are incorporated into the classic ABCD2 score for TIA risk stratification?
- A) Age, Blood pressure, Clinical features, Duration of symptoms, Diabetes
- B) Alcohol intake, Blood type, Chest pain, Depression, Diet
- C) Albumin, Bilirubin, Creatinine, Density, Diuresis
- D) Arterial blood gas values only
- Answer: A | Explanation: ABCD2 scores short-term stroke risk using Age, Blood pressure, Clinical symptoms (weakness/speech), Duration, and Diabetes.
- How does the modified ABCD3-I score improve upon the classic ABCD2 risk stratification model?
- A) It adds MRI diffusion-weighted imaging findings and carotid stenosis evaluation.
- B) It replaces clinical history with genetic testing.
- C) It only applies to pediatric patients.
- D) It eliminates blood pressure measurements.
- Answer: A | Explanation: ABCD3-I incorporates imaging (I), adding points for positive DWI lesions and significant ipsilateral carotid stenosis.
- What percentage of patients presenting with TIA will experience a subsequent major stroke within the first 48 to 72 hours if left unevaluated and untreated?
- A) Less than 0.1%
- B) Approximately 5% to 10%
- C) Exactly 75%
- D) 100%
- Answer: B | Explanation: The highest risk of subsequent stroke occurs immediately following a TIA, with roughly 5-10% of patients stroking within days.
- What is the recommended imaging workup for a patient presenting with an acute TIA within 24 hours?
- A) Plain skull radiographs only
- B) Emergency brain MRI with DWI/FLAIR and non-invasive vascular imaging (CTA or MRA head/neck)
- C) Routine electroencephalogram (EEG)
- D) Abdominal ultrasound
- Answer: B | Explanation: Rapid neurovascular imaging identifies high-risk stenoses or embolic sources requiring urgent intervention.
- What is amaurosis fugax, and what vascular pathology does it classically suggest?
- A) Transient monocular visual loss caused by retinal ischemia, typically from ipsilateral carotid artery atherosclerosis or cardioembolism
- B) Permanent bilateral blindness caused by occipital lobe trauma
- C) Temporary hearing loss from otitis media
- D) Olfactory hallucination from temporal lobe epilepsy
- Answer: A | Explanation: Amaurosis fugax is transient monocular blindness reflecting retinal transient ischemia, often originating from carotid plaque emboli.
- What is a lacunar TIA, and what vessel type is typically involved?
- A) A stroke caused by occlusion of a major trunk middle cerebral artery
- B) Transient deficit caused by ischemia in the territory of small penetrating lenticulostriate or pontine perforating end-arteries
- C) Venous sinus thrombosis of the straight sinus
- D) Large dural arteriovenous fistula
- Answer: B | Explanation: Lacunar syndromes arise from disease or occlusion of small deep penetrating perforators.
- How does cardioembolic TIA differ radiologically in distribution compared to large-vessel atherothrombotic TIA?
- A) Cardioembolic strokes typically cause isolated deep white matter punctate lesions exclusively.
- B) Cardioembolic sources frequently result in multiple scattered cortical or subcortical infarcts in different vascular territories.
- C) Cardioembolic events never show diffusion restriction.
- D) Cardioembolic events only affect the cerebellum.
- Answer: B | Explanation: Cardiac emboli tend to shower multiple emboli into varied distal branches across multiple vascular territories.
- What role does high-resolution vessel wall MRI play in evaluating cryptogenic TIA or stroke?
- A) It measures intracranial pressure.
- B) It identifies non-stenotic intracranial atherosclerotic plaque or intracranial arterial dissection/vasculitis.
- C) It evaluates bone marrow density.
- D) It replaces cardiac echocardiography.
- Answer: B | Explanation: Vessel wall MRI can detect eccentric enhancement and plaque burden in non-stenotic intracranial arteries causing embolic TIA.
- Why is rapid evaluation of carotid stenosis crucial following a TIA?
- A) Carotid endarterectomy or stenting significantly reduces recurrent stroke risk in symptomatic high-grade stenosis if performed promptly.
- B) Carotid interventions must be delayed for at least 6 months.
- C) Carotid disease never causes TIA.
- D) Surgery cures cardiac arrhythmias.
- Answer: A | Explanation: Early revascularization within 2 weeks of symptomatic high-grade carotid stenosis yields maximal risk reduction for recurrent stroke.
Category 6: Advanced CT in Hemorrhagic Stroke
- Key Concepts: Spontaneous intracerebral hemorrhage (ICH) requires rapid multidetector CT and CTA evaluation to assess hematoma volume, location, and active bleeding risk. The presence of the “spot sign” on CTA strongly predicts hematoma expansion and poor clinical outcome.
- What is the definition of the “spot sign” on CT angiography in primary intracerebral hemorrhage?
- A) A calcified pineal gland
- B) One or more foci of contrast extravasation within or adjacent to the acute hematoma
- C) Air bubbles within the ventricular system
- D) A subdural hygroma rim
- Answer: B | Explanation: The spot sign represents active contrast extravasation from ruptured microvessels, predicting ongoing bleeding and hematoma expansion.
- What patient outcome is strongly correlated with the presence of multiple spot signs on baseline CTA for acute ICH?
- A) Rapid hematoma expansion, neurological deterioration, and increased mortality
- B) Complete spontaneous resolution within 10 minutes
- C) Permanent immunity to future strokes
- D) Normalization of systemic blood pressure without medication
- Answer: A | Explanation: Spot signs identify active hemorrhage, predicting worse clinical trajectories and expansion risk.
- What is the classic distribution pattern of hypertensive intracerebral hemorrhage?
- A) Lobar cortical-subcortical junctions only
- B) Deep gray matter structures (basal ganglia, thalamus, pons, and cerebellum)
- C) Corpus callosum exclusively
- D) Optic chiasm
- Answer: B | Explanation: Chronic hypertension damages small penetrating arterioles (Charcot-Bouchard aneurysms), classically causing deep ganglionic and pontine hemorrhages.
- What is the hallmark etiology of non-hypertensive lobar intracerebral hemorrhage in elderly patients?
- A) Cerebral amyloid angiopathy (CAA)
- B) Pituitary macroadenoma apoplexy
- C) Vestibular schwannoma hemorrhage
- D) Carotid web rupture
- Answer: A | Explanation: Amyloid-beta protein deposition in cortical and leptomeningeal vessel walls predisposes elderly patients to recurrent lobar hemorrhages.
- How does unenhanced CT differentiate acute parenchymal hematoma from acute subarachnoid hemorrhage (SAH)?
- A) ICH forms a focal intraparenchymal hyperdense clot; SAH fills cerebrospinal fluid-filled basal cisterns and sulci with high attenuation.
- B) SAH only occurs inside the lateral ventricles.
- C) ICH never appears hyperdense.
- D) SAH is always hypodense compared to brain tissue.
- Answer: A | Explanation: Parenchymal hematomas form discrete intraparenchymal clots, whereas SAH distributes along subarachnoid CSF pathways and cisterns.
- What is the “black hole sign” on non-contrast CT in acute intracerebral hemorrhage?
- A) A region of dark CSF within the lateral ventricles
- B) A relatively hypodense area enclosed within a hyperdense hematoma, indicating hyperacute unclotted blood or serum extrusion and predicting expansion
- C) Air artifact from skull fracture
- D) Normal choroid plexus
- Answer: B | Explanation: The black hole sign (hypodensity within hematoma) is another validated predictor of active hematoma expansion.
- What imaging modality is most sensitive for detecting underlying vascular malformations (AVMs, dural fistulas, cavernous malformations) occulted by a massive acute ICH?
- A) Follow-up CT angiography or catheter digital subtraction angiography (DSA) performed after hematoma resorption
- B) Plain skull X-ray
- C) Non-contrast CT alone
- D) Routine chest radiograph
- Answer: A | Explanation: Initial hematoma mass effect can obscure small AVMs or cavernomas; delayed CTA or repeat DSA after clot shrinkage is often required.
- What is the classic appearance of a cavernous malformation on gradient echo (GRE) or susceptibility-weighted imaging (SWI)?
- A) A hypervascular nidus with early draining veins
- B) A well-circumscribed “popcorn” or “berry” lesion with a complete peripheral rim of dark hemosiderin susceptibility artifact
- C) Diffuse leptomeningeal enhancement without blood products
- D) A large dural-based mass with bone hyperostosis
- Answer: B | Explanation: Cavernomas show characteristic mixed-signal cores with dark hemosiderin rings on susceptibility-weighted sequences.
- What imaging features distinguish a neoplastic hemorrhage from a primary hypertensive hemorrhage?
- A) Neoplastic hemorrhages often show disproportionate surrounding vasogenic edema, irregular enhancement, and heterogeneous signal intensity.
- B) Neoplastic hemorrhages never contain blood.
- C) Hypertensive hemorrhages always occur in the cerebral cortex.
- D) Tumors never bleed.
- Answer: A | Explanation: Hemorrhagic metastases or glioblastomas exhibit disproportionate edema and abnormal nodular contrast enhancement distinct from simple hypertensive bleeds.
- What is the primary role of CT perfusion or permeability imaging in acute intracranial hemorrhage?
- A) Evaluating blood-brain barrier disruption and peri-hematomal hypoperfusion zones
- B) Measuring bone mineral density of the skull
- C) Assessing cardiac ejection fraction
- D) Guiding endotracheal tube placement
- Answer: A | Explanation: Perfusion imaging around hematomas helps delineate peri-hematomal hypoperfusion versus true metabolic ischemia.
Category 7: Blood-Brain Barrier Permeability & Perfusion Imaging
- Key Concepts: Perfusion CT and dynamic susceptibility contrast (DSC) MR quantify hemodynamic parameters (CBF, CBV, MTT, $T_{max}$). Measuring blood-brain barrier (BBB) permeability parameters like $K^{trans}$ quantifies contrast agent leakage into the extravascular space, helping predict hemorrhagic transformation risks post-stroke.
- What physiological parameter does $K^{trans}$ measure in dynamic contrast-enhanced (DCE) perfusion imaging?
- A) Total cerebral blood volume within capillaries
- B) The transfer rate constant of contrast agent leakage from the intravascular space into the extravascular extracellular space
- C) Mean transit time through venous sinuses
- D) Oxygen extraction fraction
- Answer: B | Explanation:$K^{trans}$ quantifies the permeability-surface area product, reflecting blood-brain barrier breakdown.
- How is Cerebral Blood Volume (CBV) typically defined in perfusion imaging?
- A) The volume of blood in a given volume of brain tissue, expressed in mL/100g
- B) The speed of blood flow in centimeters per second
- C) The time required for blood to cross the capillary bed
- D) The percentage of oxygen bound to hemoglobin
- Answer: A | Explanation: CBV measures vascular volume fraction within tissue (mL/100g).
- What characterizes the ischemic core on automated perfusion parameter maps (e.g., RAPID software)?
- A) Severely depressed Cerebral Blood Flow (CBF < 30% of normal contralateral tissue)
- B) Normal CBV and zero MTT delay
- C) Massive elevation in cerebral blood volume
- D) Complete absence of any imaging signal
- Answer: A | Explanation: Severe CBF reduction (<30%) defines the ischemic core representing irreversibly injured tissue.
- What is the $T_{max}$ threshold standardly used to define the total hypoperfused tissue region (penumbra + core)?
- A) $T_{max} > 2$ seconds
- B) $T_{max} > 6$ seconds
- C) $T_{max} < 1$ second
- D) $T_{max}$ exactly 0 seconds
- Answer: B | Explanation: A residue function delay ($T_{max}$) greater than 6 seconds standardly defines critically hypoperfused tissue.
- What potential artifact occurs on DSC-MRI perfusion when high concentrations of gadolinium pass through large feeding arteries?
- A) T1 shortening (“T1 shine-through”) causing paradoxical signal increase instead of drop, requiring mathematical correction
- B) Complete permanent magnet demagnetization
- C) Spontaneous cranial nerve palsy
- D) Total loss of spatial resolution
- Answer: A | Explanation: High local contrast concentrations can induce T1 shortening effects that counteract T2* signal loss, skewing perfusion calculations.
- Why does Arterial Spin Labeling (ASL) perfusion not require exogenous gadolinium contrast injection?
- A) ASL uses magnetically labeled arterial blood water protons as an endogenous tracer.
- B) ASL operates without a magnetic field.
- C) ASL only images bone structures.
- D) ASL relies on radioactive iodine tracers.
- Answer: A | Explanation: ASL magnetically tags arterial water upstream with radiofrequency pulses, using endogenous blood as the tracer.
- What is a recognized clinical limitation of Arterial Spin Labeling (ASL) in acute stroke?
- A) It cannot be performed on modern MRI scanners.
- B) Lower signal-to-noise ratio and sensitivity to delayed arterial transit times (ATD) in severe steno-occlusive disease, which can mimic hypoperfusion.
- C) It causes severe allergic reactions.
- D) It requires 4 hours of scan time.
- Answer: B | Explanation: Long arterial transit times in severe stenosis can delay labeled blood arrival, sometimes creating false perfusion deficits on ASL.
- What parameter combination distinguishes benign oligemia from the ischemic penumbra?
- A) Oligemia shows delayed arrival ($T_{max}$ delay) with preserved or elevated CBF and normal/increased CBV, whereas penumbra shows reduced CBF with elevated MTT.
- B) Oligemia shows zero blood flow.
- C) Penumbra shows normal perfusion.
- D) There is no hemodynamic difference.
- Answer: A | Explanation: Benign oligemia represents tissue receiving reduced perfusion that remains above the ischemic threshold without metabolic failure.
- How does reperfusion of an infarct core with severe BBB breakdown influence the risk of hemorrhagic transformation?
- A) It eliminates all bleeding risks.
- B) Severe BBB disruption and capillary damage significantly increase the risk of symptomatic parenchymal hematoma formation following reperfusion.
- C) It accelerates bone healing.
- D) It converts ischemic tissue into normal gray matter instantly.
- Answer: B | Explanation: Reperfusion across severely damaged, permeable capillaries can lead to extravasation and secondary hemorrhagic transformation.
- What is Mean Transit Time (MTT) in perfusion CT/MR?
- A) The average time taken for blood to travel through the capillary bed from arterial input to venous output
- B) The total duration of the MRI scan session
- C) The time the patient spends in the waiting room
- D) The speed of cerebrospinal fluid flow
- Answer: A | Explanation: MTT represents the average transit duration of blood through the microvasculature.
Category 8: Extended Window Mechanical Thrombectomy (DAWN/DEFUSE 3 Era)
- Key Concepts: Landmark trials (DAWN and DEFUSE 3) revolutionized extended-window (6–24 hours) mechanical thrombectomy by using advanced perfusion imaging to identify patients with a favorable tissue mismatch—meaning a small established infarct core alongside a large critically hypoperfused salvageable penumbra.
- What was the primary inclusion time window evaluated by the landmark DAWN and DEFUSE 3 clinical trials?
- A) 0 to 3 hours only
- B) 6 to 24 hours from last known well
- C) Exactly 48 to 72 hours
- D) After 1 week
- Answer: B | Explanation: DAWN and DEFUSE 3 evaluated mechanical thrombectomy effectiveness in the extended 6-to-24-hour window post-stroke onset.
- According to DAWN trial criteria, what clinical-core mismatch determined eligibility for thrombectomy in patients aged $>80$ with an NIHSS $\ge 10$?
- A) Small clinical deficit with massive necrotic core
- B) High clinical severity (NIHSS $\ge 10$) combined with a small infarct core volume ($< 21$ mL) determined by automated perfusion software
- C) Zero neurological deficit
- D) Normal blood pressure
- Answer: B | Explanation: DAWN matched severe clinical deficits against small imaging core volumes to prove salvageable tissue existed up to 24 hours.
- What core volume upper limit was standardly utilized in the DEFUSE 3 trial for patient selection in the 6–16 hour window?
- A) Infarct core volume less than 70 mL with a mismatch ratio $\ge 1.8$ and mismatch volume $\ge 15$ mL
- B) Infarct core volume greater than 200 mL
- C) Core volume exactly zero
- D) No imaging criteria required
- Answer: A | Explanation: DEFUSE 3 required a core < 70 mL, a mismatch ratio $\ge 1.8$, and a mismatch volume $\ge 15$ mL to proceed with thrombectomy.
- What is the primary goal of mechanical thrombectomy in acute large-vessel occlusion (LVO)?
- A) Permanent closure of collateral vessels
- B) Mechanical retrieval or aspiration of intracranial thrombus to restore immediate cerebral blood flow and salvage the penumbra
- C) Lowering intracranial pressure by removing skull bone
- D) Delivering systemic antibiotics
- Answer: B | Explanation: Thrombectomy physically removes occluding clots from proximal intracranial arteries, restoring rapid perfusion.
- Which intracranial vessels are the primary targets for mechanical thrombectomy in acute ischemic stroke?
- A) Internal carotid artery terminus (ICA-T), M1/M2 segments of the MCA, and basilar artery
- B) Distal retinal arterioles only
- C) External carotid artery branches
- D) Superficial temporal veins
- Answer: A | Explanation: Large vessel occlusions (ICA terminus, proximal MCA M1/M2, and basilar trunks) are the primary targets for endovascular retrieval.
- What is the TICI (Thrombolysis in Cerebral Infarction) scale used to assess?
- A) The severity of patient headache
- B) The degree of post-procedural reperfusion achieved downstream from the treated occlusion site (ranging from 0 [no perfusion] to 3 [complete reperfusion])
- C) The amount of intravenous contrast administered
- D) Patient cholesterol levels
- Answer: B | Explanation: TICI grading evaluates angiographic reperfusion success post-thrombectomy, with TICI 2b/3 representing successful revascularization.
- What complication is evaluated by immediate post-procedural non-contrast CT following mechanical thrombectomy?
- A) Contrast staining vs. acute procedural parenchymal hemorrhage
- B) Dental cavity formation
- C) Sinusitis resolution
- D) Mastoid air cell pneumatization
- Answer: A | Explanation: Post-procedure NCCT distinguishes high-attenuation iodinated contrast staining from true acute intracranial hemorrhage.
- How does dual-energy CT or follow-up CT at 24 hours help resolve the ambiguity between iodine contrast staining and hemorrhage after thrombectomy?
- A) Contrast staining washes out rapidly over 24 hours and shows dual-energy material decomposition iodine subtraction, whereas true hemorrhage persists with high attenuation.
- B) CT scans cannot differentiate iodine from blood.
- C) Contrast staining turns green at 24 hours.
- D) True blood disappears instantly.
- Answer: A | Explanation: Iodine contrast extravasation washes out and demonstrates dual-energy iodine subtraction, whereas acute blood hematoma remains hyperdense.
- What is “stent-retriever” thrombectomy?
- A) A surgical procedure to bypass neck arteries
- B) Deployment of a self-expanding nitinol mesh stent across the thrombus to trap and pull the clot out under aspiration control
- C) Injection of clot-dissolving enzymes into peripheral veins
- D) Placement of permanent clips on carotid arteries
- Answer: B | Explanation: Stent-retrievers trap thrombi within their struts for mechanical extraction.
- What is aspiration-based thrombectomy (e.g., ADAPT technique)?
- A) Using a large-bore aspiration catheter placed directly at the face of the thrombus to ingest the clot via negative suction pressure
- B) Manual chest compressions
- C) Sucking cerebrospinal fluid out of ventricles
- D) Using laser energy to vaporize the skull
- Answer: A | Explanation: Aspiration techniques apply direct vacuum suction through large-bore catheter lumens to engage and ingest intracranial thrombi.
Category 9: Arterial Spin Labeling (ASL) & Perfusion MRI
- Key Concepts: Arterial Spin Labeling (ASL) uses magnetically labeled arterial water protons as an endogenous tracer for perfusion MRI, eliminating the need for exogenous gadolinium. This is particularly valuable in acute stroke, serial monitoring, and patients with renal impairment.
- What magnetic manipulation is applied to arterial blood in Arterial Spin Labeling (ASL) prior to brain imaging?
- A) Saturation or inversion radiofrequency pulses applied to inflowing blood in neck arteries to invert or alter their magnetization
- B) Injection of radioactive gold nanoparticles
- C) Total suppression of all brain water protons
- D) Application of static X-ray beams
- Answer: A | Explanation: ASL magnetically labels (inverts) arterial water protons in feeding arteries proximal to the imaging slab.
- Why is subtraction of labeled and control images essential in ASL perfusion processing?
- A) Control images remove background static tissue signal, leaving only the tiny signal difference contributed by the inflowing labeled water bolus.
- B) Subtraction removes all bone artifacts.
- C) It measures patient heart rate.
- D) It converts MRI into CT.
- Answer: A | Explanation: The labeled blood signal change is extremely small (approx. 1%); subtraction of control and labeled scans isolates this perfusion signal.
- What is the primary safety benefit of ASL over Dynamic Susceptibility Contrast (DSC) MR perfusion?
- A) ASL requires no intravenous gadolinium contrast administration, avoiding nephrogenic systemic fibrosis and allergic risks.
- B) ASL requires no magnetic field.
- C) ASL scanning takes less than 1 second.
- D) ASL uses no radiofrequency energy.
- Answer: A | Explanation: ASL uses endogenous blood water as a tracer, entirely avoiding exogenous contrast agents.
- What is a major technical challenge affecting ASL image quality in elderly patients or those with severe atherosclerosis?
- A) Excessive bone calcification
- B) Delayed arterial transit times (ATD) causing labeled blood to decay or fail to reach tissue within the post-labeling delay window, mimicking false perfusion deficits
- C) Inability of the scanner to turn on
- D) Complete loss of patient breathing
- Answer: B | Explanation: Slowed flow in severe steno-occlusive disease delays blood arrival past standard delay times, causing false hypoperfusion on ASL.
- How does Pseudo-Continuous ASL (pCASL) improve upon older continuous ASL (CASL) methods?
- A) It uses a train of discrete radiofrequency pulses combined with gradient modulation to mimic continuous labeling with higher efficiency and lower RF power deposition.
- B) It requires no radiofrequency pulses.
- C) It operates only on 0.1 Tesla veterinary scanners.
- D) It eliminates all patient motion.
- Answer: A | Explanation: pCASL achieves high labeling efficiency safely using train pulses instead of continuous high-power RF irradiation.
- What is the typical clinical utility of ASL in pediatric neuroimaging or pregnancy?
- A) It provides safe, non-invasive serial perfusion evaluation without contrast risks in vulnerable populations.
- B) It measures fetal bone age.
- C) It replaces all blood tests.
- D) It diagnoses congenital heart murmurs.
- Answer: A | Explanation: Avoiding gadolinium makes ASL exceptionally valuable for pediatric and pregnant patients requiring perfusion assessment.
- How does hyperperfusion manifest on ASL perfusion maps in conditions like seizure foci or post-endarterectomy syndrome?
- A) Marked regional hyperintensity (increased CBF) within the affected cortical or subcortical territory
- B) Complete black signal void
- C) Disappearance of all brain tissue
- D) Symmetrical bilateral zero flow
- Answer: A | Explanation: Seizure foci or luxury perfusion states exhibit markedly elevated regional cerebral blood flow on ASL maps.
- What parameter represents Post-Labeling Delay (PLD) in ASL protocols?
- A) The waiting time allowed for magnetically labeled blood to travel from the labeling plane to the tissue capillary bed before image acquisition
- B) The time the patient waits before entering the hospital
- C) The time taken to reconstruct images on the computer
- D) The scanner gradient cooling time
- Answer: A | Explanation: PLD ensures labeled blood has sufficient time to reach distal microvessels before data readout.
- Why can multi-PLD ASL acquisitions help overcome arterial transit time artifacts in steno-occlusive disease?
- A) Sampling multiple delay times captures slow-arriving blood boluses, yielding more accurate cerebral blood flow quantification.
- B) It shortens scan time to 2 seconds.
- C) It eliminates the need for gradient coils.
- D) It increases magnetic field strength.
- Answer: A | Explanation: Multi-PLD acquisitions measure arrival kinetics, mitigating transit time errors in delayed flow states.
- How do ASL cerebral blood flow (CBF) values generally correlate with quantitative [15O] H2O PET measurements (the gold standard)?
- A) They show strong positive correlation, validating ASL as a reliable quantitative perfusion MRI technique.
- B) They show zero correlation.
- C) PET shows negative values while ASL shows positive numbers.
- D) PET cannot measure blood flow.
- Answer: A | Explanation: Validated studies demonstrate good correlation between ASL-derived CBF and PET radiotracer measurements.
Category 10: Vascular Territories of the Brain & Venous Infarction
- Key Concepts: Mastery of arterial and venous distributions prevents diagnostic misinterpretation. Arterial strokes follow wedge-shaped vascular boundaries supplied by major trunks and perforators, whereas cerebral venous sinus thrombosis (CVST) causes non-arterial, patchy, bilateral hemorrhagic infarctions crossing standard borderzones.
- An infarction involving the medial frontal and parietal cortex, including the paracentral lobule and causing contralateral lower-extremity motor/sensory deficits, stems from occlusion of which artery?
- A) Recurrent artery of Heubner
- B) Pericallosal artery (distal anterior cerebral artery branch)
- C) Middle cerebral artery M2 segment
- D) Anterior choroidal artery
- Answer: B | Explanation: The pericallosal and callosomarginal arteries supply the medial hemispheric surfaces and paracentral lobule (lower limb motor/sensory representation).
- What classic clinical triad characterizes Anterior Choroidal Artery syndrome?
- A) Contralateral hemiplegia, contralateral hemisensory loss, and contralateral homonymous hemianopia
- B) Ipsilateral facial droop and hearing loss
- C) Isolated aphasia without motor deficit
- D) Bilateral lower limb paralysis with normal sensation
- Answer: A | Explanation: The anterior choroidal artery supplies the posterior limb of internal capsule, optic tract, and cerebral peduncle, causing the classic triad.
- Where are internal borderzone (watershed) infarcts typically located?
- A) Deep subcortical white matter in a linear string-of-pearls distribution parallel to the lateral ventricle, between the superficial and deep MCA/ACA systems
- B) Brainstem center
- C) Cerebellar tonsils
- D) Occipital pole cortex
- Answer: A | Explanation: Internal borderzones lie in deep white matter between superficial and deep arterial supply territories, vulnerable to systemic hypoperfusion.
- What clinical syndrome results from occlusion of paramedian pontine perforating branches of the basilar artery?
- A) Wallenberg syndrome
- B) Locked-in syndrome (quadriplegia and preserved vertical eye movement/consciousness)
- C) Pure sensory stroke of the hand
- D) Weber syndrome
- Answer: B | Explanation: Bilateral ventral pontine infarction destroys corticospinal and corticobulbar tracts while sparing tegmental reticular activating systems, causing locked-in syndrome.
- What is the hallmark imaging presentation of cerebral venous sinus thrombosis (CVST) on unenhanced brain CT?
- A) The “dense triangle” sign (hyperdense thrombus within the superior sagittal sinus) or cord sign in cortical veins
- B) Symmetric cortical calcifications
- C) Complete absence of intracranial ventricles
- D) Bilateral symmetrical frontal lobe hypodensity only
- Answer: A | Explanation: Acute thrombus within dural sinuses yields high attenuation on unenhanced CT (dense triangle or cord sign).
- How do venous infarcts differ radiologically from arterial territory infarcts?
- A) Venous infarcts strictly follow narrow arterial bifurcation zones.
- B) Venous infarcts frequently cross arterial boundaries, appear patchy, and commonly exhibit prominent hemorrhagic transformation.
- C) Venous infarcts never show edema.
- D) Venous infarcts occur exclusively in the spinal cord.
- Answer: B | Explanation: Venous outflow obstruction raises capillary pressure, leading to non-arterial distribution, petechial hemorrhages, and edema.
- What is Wallenberg syndrome (lateral medullary syndrome), and which vessel occlusion causes it?
- A) Occlusion of the Posterior Inferior Cerebellar Artery (PICA) or vertebral artery, causing ipsilateral ataxia, Horner syndrome, facial pain/temperature loss, and contralateral body pain/temperature loss
- B) Occlusion of the anterior cerebral artery
- C) Occlusion of the middle cerebral artery upper trunk
- D) Internal carotid artery dissection
- Answer: A | Explanation: Lateral medullary infarction from PICA/vertebral occlusion produces crossed sensory loss, Horner’s, and ataxia.
- What is the Artery of Percheron variant, and what imaging finding characterizes its occlusion?
- A) A single unpaired arterial trunk arising from a proximal PCA segment supplying bilateral paramedian thalami and rostral midbrain, where occlusion produces characteristic bilateral paramedian thalamic infarcts.
- B) A duplication of the basilar artery
- C) A congenital aneurysm of the anterior communicating artery
- D) A persistent trigeminal artery
- Answer: A | Explanation: Percheron variants feature a single stem supplying bilateral medial thalami, leading to symmetric bilateral paramedian thalamic infarcts.
- Which cortical MCA branch division supplies language centers (Broca’s area) in the dominant hemisphere?
- A) Inferior division of the MCA
- B) Superior division of the MCA
- C) Posterior cerebral artery
- D) Anterior choroidal artery
- Answer: B | Explanation: The superior division of the MCA supplies the frontal operculum, including Broca’s area in the dominant hemisphere.
- What is the diagnostic role of CT venography (CTV) or MR venography (MRV) in suspected cerebral venous thrombosis? * A) To measure systemic blood pressure * B) To visualize filling defects and absent flow within dural venous sinuses and cortical veins confirming thrombosis * C) To evaluate bone fracture healing * D) To assess cardiac valve function * > Answer: B | Explanation: CTV and MRV demonstrate intraluminal filling defects and loss of normal venous outflow, confirming CVST.
Naveed Ahmad | Orlando FL | RadQuiz.com