Neuroradiology — MCQs

Neuroradiology Indian Medical PG Practice Questions and MCQs

Question 191: Abnormal signals in bilateral thalami on MRI brain are seen in which of the following conditions?

A. Wilson's disease
B. Japanese encephalitis (Correct Answer)
C. Wernicke's encephalopathy
D. Rasmussen's encephalitis

Explanation: **Explanation:** The presence of **bilateral thalamic involvement** on MRI is a classic neuroimaging hallmark for several specific conditions, most notably **Japanese Encephalitis (JE)**. **1. Why Japanese Encephalitis is correct:** JE is a flavivirus infection with a unique predilection for the deep gray matter nuclei. MRI typically shows T2/FLAIR hyperintensities in the **thalami (most common)**, basal ganglia, substantia nigra, and brainstem. Thalamic lesions are often bilateral and may show hemorrhagic transformation, which is highly suggestive of JE in an endemic setting. **2. Analysis of Incorrect Options:** * **Wilson’s Disease:** While it involves the basal ganglia, the characteristic MRI finding is the **"Face of the Giant Panda"** sign (midbrain) and the "Miniature Panda" sign (pons). Thalamic involvement can occur but is usually secondary to prominent lentiform nucleus changes. * **Wernicke’s Encephalopathy:** This condition classically involves the **mammillary bodies**, periaqueductal gray matter, and the **dorsomedial thalami**. While it involves the thalami, JE is the more "classic" answer for generalized bilateral thalamic signals in a viral prodrome context. * **Rasmussen’s Encephalitis:** This is a chronic inflammatory disease characterized by **unilateral** hemispheric atrophy and progressive neurological deficit. It does not present with bilateral thalamic signals. **High-Yield Clinical Pearls for NEET-PG:** * **Differential Diagnosis for Bilateral Thalamic Lesions:** Japanese Encephalitis, Artery of Percheron infarct, Wernicke’s Encephalopathy, and Deep Venous Thrombosis (Internal Cerebral Veins). * **JE Key Feature:** Look for "Thalamic involvement with hemorrhage" in the clinical stem. * **Artery of Percheron:** A rare anatomical variant where a single arterial trunk supplies bilateral paramedian thalami; occlusion leads to sudden onset bilateral thalamic infarcts.

Question 192: Which sequence of MRI is used to detect microhemorrhages?

A. T1WI
B. T2WI
C. SWI (Correct Answer)
D. DWI

Explanation: **Explanation:** The correct answer is **SWI (Susceptibility Weighted Imaging)**. **1. Why SWI is the Correct Answer:** SWI is a high-spatial-resolution 3D gradient-echo sequence that is extremely sensitive to substances that cause "magnetic susceptibility" effects, such as **hemosiderin** (from old blood) and **calcium**. * **Mechanism:** When microhemorrhages occur, hemoglobin breaks down into paramagnetic hemosiderin. This creates local magnetic field distortions, leading to a loss of signal. On SWI, these appear as small, dark "blooming" spots (the **Blooming Effect**). SWI is significantly more sensitive than conventional T2* Gradient Echo (GRE) for detecting tiny punctate hemorrhages. **2. Why Other Options are Incorrect:** * **T1WI (T1 Weighted Imaging):** Primarily used for anatomy. While acute/subacute blood can appear bright (hyperintense) on T1, it lacks the sensitivity to detect chronic microhemorrhages. * **T2WI (T2 Weighted Imaging):** Standard T2 sequences are poor at detecting microbleeds as they do not emphasize magnetic susceptibility. * **DWI (Diffusion Weighted Imaging):** This sequence measures the random motion of water molecules. It is the "Gold Standard" for detecting **Hyperacute Ischemic Stroke** (cytotoxic edema), not microhemorrhages. **3. High-Yield Clinical Pearls for NEET-PG:** * **Differential Diagnosis for Microhemorrhages:** 1. **Hypertensive Microbleeds:** Usually located in the basal ganglia, thalamus, and pons. 2. **Cerebral Amyloid Angiopathy (CAA):** Characteristically located in the **peripheral/lobar** cortical-subcortical junctions. 3. **Diffuse Axonal Injury (DAI):** Microhemorrhages at the grey-white matter junction, corpus callosum, or brainstem following trauma. * **Mnemonic:** "SWI for Blood and Bone (Calcium)." * **Comparison:** If both GRE and SWI are in options, **SWI** is the superior choice for microhemorrhage detection.

Question 193: What is the earliest sign of raised intracranial tension on a skull X-ray in infants?

A. Sutural diastasis (Correct Answer)
B. Erosion of the dorsum sellae
C. Pineal gland displacement
D. Copper beaten appearance

Explanation: **Explanation:** In infants and young children (typically under the age of 2), the cranial sutures are not yet fused. When intracranial pressure (ICP) rises, the skull expands to accommodate the volume. **Sutural diastasis** (widening of the sutures) is the **earliest and most sensitive sign** of raised ICP in this age group. A suture width of >2 mm is generally considered abnormal. **Analysis of Options:** * **A. Sutural diastasis (Correct):** Because the infant skull is compliant, the sutures separate before any bony erosion occurs. This is the pediatric equivalent of the "erosion of dorsum sellae" seen in adults. * **B. Erosion of the dorsum sellae:** This is the **most common** and earliest sign of raised ICP in **adults**. In infants, the sutures give way first, making this a later or less common sign. * **C. Pineal gland displacement:** This indicates a midline shift due to a space-occupying lesion (e.g., tumor or hematoma). While it suggests increased pressure, it is a sign of mass effect rather than a generalized early sign of raised ICP. Furthermore, the pineal gland is rarely calcified (and thus not visible) in infants. * **D. Copper beaten appearance (Silver beaten skull):** This refers to prominent gyral impressions on the inner table of the skull. While associated with chronic raised ICP (like craniosynostosis), it can be a **normal finding** in healthy children during periods of rapid brain growth (ages 4–10) and is therefore not a reliable early sign. **High-Yield Clinical Pearls for NEET-PG:** * **Adults:** Earliest sign on X-ray is erosion of the **dorsum sellae**. * **Infants:** Earliest sign is **sutural diastasis**. * **Gold Standard:** While X-ray shows chronic changes, **Non-Contrast CT (NCCT)** is the investigation of choice for acute raised ICP to look for midline shift and effacement of sulci.

Question 194: What is the first investigation of choice in a patient with suspected subarachnoid hemorrhage?

A. Non-contrast computed tomography (Correct Answer)
B. CSF examination
C. Magnetic resonance imaging (MRI)
D. Contrast-enhanced computed tomography

Explanation: **Explanation:** **Non-contrast Computed Tomography (NCCT) Head** is the gold standard first investigation for suspected Subarachnoid Hemorrhage (SAH). Its primary advantage is high sensitivity (nearly 98-100% within the first 6–12 hours) for detecting acute blood in the subarachnoid spaces. Acute blood appears **hyperdense** (bright white) on NCCT, typically seen in the basal cisterns, Sylvian fissures, and sulci. It is preferred because it is fast, widely available, and highly effective at ruling out other causes of sudden headache, such as intracranial hemorrhage. **Why other options are incorrect:** * **CSF Examination:** While lumbar puncture (looking for xanthochromia) is the most sensitive test for SAH, it is only performed if the NCCT is negative but clinical suspicion remains high. It is invasive and carries a risk of herniation if intracranial pressure is elevated. * **MRI:** Though sensitive for subacute blood (using FLAIR or SWI sequences), MRI is time-consuming, less available in emergencies, and difficult for unstable patients. * **Contrast-enhanced CT (CECT):** Contrast is avoided initially because it can mimic the appearance of subarachnoid blood (hyperdensity), potentially masking a hemorrhage or leading to a false positive. **High-Yield Clinical Pearls for NEET-PG:** * **Classic Presentation:** "Thunderclap headache" or the "worst headache of my life." * **Most Common Cause:** Trauma (overall); Rupture of a Berry aneurysm (spontaneous/non-traumatic). * **Star Sign:** On NCCT, blood in the basal cisterns often creates a characteristic "star-shaped" hyperdensity. * **Gold Standard for Aneurysm:** Digital Subtraction Angiography (DSA) is the gold standard for identifying the source/site of bleeding, but not the initial diagnosis of SAH.

Question 195: Which arteries supply the cerebellum?

A. Vertebral artery
B. Basilar artery
C. Both (Correct Answer)
D. None

Explanation: The arterial supply of the cerebellum is derived from the **Vertebrobasilar system**, which forms the posterior circulation of the brain. ### **Explanation of the Correct Answer** The cerebellum is supplied by three main pairs of arteries, which originate from both the vertebral and basilar arteries: 1. **Posterior Inferior Cerebellar Artery (PICA):** This is the largest branch of the **Vertebral Artery**. It supplies the posteroinferior aspect of the cerebellum and the choroid plexus of the fourth ventricle. 2. **Anterior Inferior Cerebellar Artery (AICA):** This arises from the lower part of the **Basilar Artery**. It supplies the anterior part of the inferior surface of the cerebellum. 3. **Superior Cerebellar Artery (SCA):** This arises from the distal part of the **Basilar Artery** (just before its bifurcation into the posterior cerebral arteries). It supplies the superior surface of the cerebellum. Since the blood supply originates from branches of both the vertebral and basilar arteries, **Option C** is the correct answer. ### **Why Other Options are Incorrect** * **Option A & B:** These are incomplete. Selecting only one ignores the significant contribution of the other major vessel in the vertebrobasilar system. ### **High-Yield Clinical Pearls for NEET-PG** * **PICA Occlusion:** Leads to **Lateral Medullary Syndrome (Wallenberg Syndrome)**. A classic sign is "crossed sensory loss" (ipsilateral face, contralateral body). * **AICA Occlusion:** Leads to **Lateral Pontine Syndrome**. A key differentiating feature from PICA syndrome is the presence of **ipsilateral facial paralysis and deafness** (due to involvement of CN VII and VIII). * **Rule of 4s:** Remember that the cerebellum is part of the posterior fossa; its blood supply is intimately linked to the brainstem (Medulla = PICA, Pons = AICA/SCA).

Question 196: Which condition is characterized by the 'face of the panda' appearance on MRI?

A. Wilson disease (Correct Answer)
B. Menke disease
C. Huntington chorea
D. Parkinsonism

Explanation: ### Explanation **Correct Answer: A. Wilson Disease** The **'Face of the Giant Panda'** sign is a classic neuroimaging hallmark of Wilson Disease (Hepatolenticular degeneration), an autosomal recessive disorder of copper metabolism. * **Mechanism:** This appearance is seen on **T2-weighted MRI** images of the midbrain. It results from a combination of high signal intensity (hyperintensity) in the tegmentum and low signal intensity (hypomagnesemia/paramagnetic effects) in the red nuclei and substantia nigra. * **Anatomy of the "Panda":** The red nuclei represent the "eyes," the pars reticulata of the substantia nigra represents the "ears," and the superior colliculus represents the "chin." **Why the other options are incorrect:** * **B. Menke Disease:** This is an X-linked recessive disorder of copper *deficiency* (ATP7A mutation). Imaging typically shows diffuse cerebral atrophy, delayed myelination, and "tortuous" intracranial vessels (kinky hair disease), but not the panda sign. * **C. Huntington Chorea:** Characterized by atrophy of the **caudate nucleus**, leading to the enlargement of the frontal horns of the lateral ventricles (box-car ventricles). * **D. Parkinsonism:** Often shows thinning of the substantia nigra or the **"swallow tail sign"** (loss of nigrosome-1) on high-resolution susceptibility-weighted imaging (SWI). **High-Yield Clinical Pearls for NEET-PG:** * **Double Panda Sign:** Seen when the "Face of the Giant Panda" in the midbrain is combined with a "Miniature Panda" appearance in the pons (due to changes in the central tegmental tracts). * **Other Wilson Signs:** Look for the **"Bright Claustrum"** sign on MRI. * **Diagnosis:** Low serum ceruloplasmin, high 24-hour urinary copper, and **Kayser-Fleischer (KF) rings** on slit-lamp exam. * **Treatment:** Chelating agents like D-Penicillamine or Zinc (to prevent absorption).

Question 197: Which condition is characterized by the MRI finding of "tectal beaking"?

A. Dandy-Walker malformation
B. Arnold-Chiari malformation (Correct Answer)
C. Aqueductal stenosis
D. Third ventricular tumor

Explanation: ### Explanation **Correct Answer: B. Arnold-Chiari malformation** **Tectal beaking** is a classic neuroimaging sign specifically associated with **Chiari II malformation**. It refers to the fusion and posterior pointing (beaking) of the colliculi of the midbrain. This occurs because the small posterior fossa and the downward displacement of the hindbrain structures cause the midbrain to be pulled inferiorly and squeezed, resulting in the characteristic "beaked" appearance of the tectal plate on sagittal MRI. **Analysis of Incorrect Options:** * **A. Dandy-Walker malformation:** Characterized by the triad of cystic dilatation of the fourth ventricle, cerebellar vermis hypoplasia, and an enlarged posterior fossa. It does not involve tectal plate distortion. * **C. Aqueductal stenosis:** While it causes obstructive hydrocephalus and can lead to thinning of the corpus callosum, it typically presents with a normal or "bulging" tectum rather than a fused, beaked one. * **D. Third ventricular tumor:** These (e.g., colloid cysts) cause obstructive hydrocephalus and pressure symptoms but do not result in the structural hindbrain herniation required to produce tectal beaking. **High-Yield Clinical Pearls for NEET-PG:** * **Chiari II Malformation Triad:** Tectal beaking, downward displacement of the cerebellar tonsils/vermis/medulla, and association with **myelomeningocele** (nearly 100%). * **Other Chiari II Signs:** "Towering cerebellum" (upward herniation through the tentorium) and "Luckenschadel skull" (lacunar skull). * **Chiari I:** Only cerebellar tonsillar herniation (>5mm); usually asymptomatic until adulthood and associated with **syringomyelia**.

Question 198: The "Eye of the Tiger" appearance in MRI is seen in which of the following conditions?

A. Wilson's disease
B. Neuronal accumulation of iron
C. Alzheimer's disease
D. Hallervorden-Spatz syndrome (Correct Answer)

Explanation: **Explanation:** The **"Eye of the Tiger"** sign is a classic radiological hallmark seen on **T2-weighted MRI** of the brain. It is pathognomonic for **Hallervorden-Spatz syndrome**, now more commonly known as **Pantothenate Kinase-Associated Neurodegeneration (PKAN)**, a type of Neurodegeneration with Brain Iron Accumulation (NBIA). **Pathophysiology:** The sign consists of a central area of **hyperintensity** (high signal) surrounded by a rim of **hypointensity** (low signal) in the **Globus Pallidus**. * **Hypointensity:** Caused by excessive iron deposition (paramagnetic effect). * **Hyperintensity:** Represents gliosis, vacuolization, and axonal swelling (spheroid bodies). **Analysis of Options:** * **Option D (Correct):** Hallervorden-Spatz syndrome (PKAN) is the primary condition associated with this sign due to the specific pattern of iron and gliosis in the globus pallidus. * **Option A:** **Wilson’s Disease** typically shows the **"Face of the Giant Panda"** sign in the midbrain (high signal in tegmentum with preserved normal signal in red nuclei and superior colliculi). * **Option B:** While PKAN involves iron accumulation, "Neuronal accumulation of iron" is a broad category. The "Eye of the Tiger" is specifically linked to the PKAN subtype of NBIA. * **Option C:** **Alzheimer’s Disease** is characterized by generalized cortical atrophy and hippocampal atrophy, not specific basal ganglia iron patterns. **NEET-PG High-Yield Pearls:** 1. **Gene Mutation:** PKAN is caused by a mutation in the **PANK2 gene** (Chromosome 20p). 2. **Clinical Triad:** Extrapyramidal symptoms (dystonia, rigidity), pigmentary retinopathy, and cognitive decline. 3. **MRI Sequence:** The sign is best visualized on **T2-weighted** or **SWI** (Susceptibility Weighted Imaging) sequences.

Question 199: What is the most common location of hypertensive intracranial hemorrhage?

A. Subarachnoid space
B. Basal ganglia (Correct Answer)
C. Cerebellum
D. Brainstem

Explanation: **Explanation:** **Hypertensive Intracranial Hemorrhage (ICH)** occurs due to the rupture of small, deep penetrating arteries (such as the lenticulostriate arteries) that have undergone degenerative changes like **lipohyalinosis** and the formation of **Charcot-Bouchard aneurysms** due to chronic hypertension. **Why Basal Ganglia is Correct:** The **Putamen** (within the basal ganglia) is the single most common site for hypertensive ICH, accounting for approximately 35–50% of cases. The Thalamus is the second most common site. These areas are supplied by small, non-collateralizing vessels that branch directly off high-pressure major arteries (like the Middle Cerebral Artery), making them highly susceptible to pressure-induced rupture. **Analysis of Incorrect Options:** * **Subarachnoid space:** This is the typical location for bleeding due to a **ruptured berry aneurysm** or trauma, not primary hypertensive intraparenchymal hemorrhage. * **Cerebellum:** While a common site for hypertensive bleeds (approx. 10%), it is significantly less frequent than the basal ganglia. * **Brainstem:** Specifically the **Pons**, is a classic site for hypertensive ICH, but it accounts for only about 5–10% of cases. **NEET-PG High-Yield Pearls:** * **Order of Frequency:** Putamen (most common) > Thalamus > Pons > Cerebellum. * **Imaging Gold Standard:** Non-contrast CT (NCCT) Head is the investigation of choice to differentiate between ischemic and hemorrhagic stroke acutely. * **Charcot-Bouchard Aneurysms:** These are microscopic aneurysms (0.1–0.3 mm) in small perforating arteries, distinct from Saccular (Berry) aneurysms found in the Circle of Willis. * **Lobal Hemorrhage:** If a bleed occurs in the cortex/lobes (sparing the basal ganglia) in an elderly non-hypertensive patient, suspect **Amyloid Angiopathy**.

Question 200: The "Delta sign" on CT head is typically associated with which of the following conditions?

A. Cerebral infarct
B. Superior sagittal sinus thrombosis (Correct Answer)
C. Subarachnoid hemorrhage
D. Epidural hematoma

Explanation: ### Explanation **Correct Answer: B. Superior sagittal sinus thrombosis** The **"Empty Delta Sign"** is a classic radiological hallmark of dural venous sinus thrombosis (specifically the superior sagittal sinus) seen on **contrast-enhanced CT**. * **Pathophysiology:** The "delta" refers to the triangular shape of the superior sagittal sinus in cross-section. When a thrombus is present, the contrast flows through the collateral venous channels in the dural envelope surrounding the sinus, but cannot penetrate the central clot. * **Radiological Appearance:** This creates a **central non-enhancing (dark) area** (the thrombus) surrounded by a **peripheral enhancing (bright) rim** (the dura/collaterals), resembling the Greek letter Delta (Δ). **Analysis of Incorrect Options:** * **A. Cerebral Infarct:** Typically presents as a wedge-shaped area of hypoattenuation (darkness) involving both gray and white matter, following a specific arterial territory, not a venous sinus pattern. * **C. Subarachnoid Hemorrhage:** Characterized by hyperdensity (brightness) within the sulci, cisterns, and the Sylvian fissure. * **D. Epidural Hematoma:** Appears as a hyperdense, biconvex (lens-shaped) collection that does not cross cranial sutures. **High-Yield Clinical Pearls for NEET-PG:** * **Empty Delta Sign:** Seen on **Contrast CT**. * **Dense Triangle Sign:** Seen on **Non-contrast CT** (represents the hyperdense fresh clot itself). * **Cord Sign:** A linear hyperdensity on non-contrast CT representing a thrombosed cortical vein. * **Gold Standard Investigation:** MR Venogram (MRV) is the investigation of choice for dural venous sinus thrombosis. * **Clinical Context:** Often presents in postpartum women, patients on OCPs, or those with dehydration/prothrombotic states.

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