Neuroradiology — MCQs

Neuroradiology Indian Medical PG Practice Questions and MCQs

Question 171: A patient presents with proptosis and abducent nerve palsy. A dark homogenous mass is seen on T2W MRI, which shows intense enhancement with contrast. What is the diagnosis?

A. Cavernous hemangioma (Correct Answer)
B. Meningioma
C. Astrocytoma
D. Glioma

Explanation: **Explanation:** The clinical presentation of proptosis and abducent nerve (CN VI) palsy, combined with specific MRI findings, points directly to an **Orbital Cavernous Hemangioma**. 1. **Why Cavernous Hemangioma is correct:** * **Clinical:** It is the most common benign orbital tumor in adults, typically causing slowly progressive proptosis. * **MRI Characteristics:** On T2-weighted imaging, these lesions characteristically appear as **well-circumscribed, dark (hypointense) to intermediate** masses relative to the bright orbital fat, but they are often described as **homogeneously hyperintense** compared to muscle. * **Contrast Enhancement:** They show **intense, progressive enhancement** (often starting patchy and becoming homogenous) due to the slow-flowing blood within the vascular spaces. 2. **Why other options are incorrect:** * **Meningioma:** Specifically Optic Nerve Sheath Meningiomas show the "Tram-track sign" on contrast CT/MRI. While they enhance, they are usually tubular and follow the nerve's course rather than appearing as a discrete mass. * **Astrocytoma/Glioma:** Optic nerve gliomas typically cause fusiform enlargement of the optic nerve and are associated with Neurofibromatosis Type 1 (NF1). They do not typically present as a "dark homogenous mass" on T2 in this specific clinical context. **High-Yield Pearls for NEET-PG:** * **Most common benign orbital tumor in adults:** Cavernous Hemangioma. * **Most common benign orbital tumor in children:** Capillary Hemangioma (often regresses spontaneously). * **T2 MRI Rule:** Most vascular tumors are bright on T2; however, the "dark" description in the question refers to its appearance relative to the surrounding high-signal orbital fat. * **Key Sign:** "Filling-in" phenomenon (progressive enhancement on delayed scans) is a hallmark of cavernous lesions.

Question 172: Which of the following is NOT a typical finding in meningioma?

A. Vascular markings around falx
B. Calcification
C. Erosion (Correct Answer)
D. Osteosclerosis

Explanation: **Explanation:** Meningiomas are the most common benign intracranial tumors, arising from the arachnoid cap cells. The key to answering this question lies in understanding the tumor's effect on the adjacent bone. **Why "Erosion" is the correct answer:** Meningiomas are typically slow-growing, extra-axial tumors. Rather than destroying or eroding the bone (which is more characteristic of malignant tumors or metastases), they tend to provoke a reactive bone response. While pressure atrophy can occur in rare cases, **erosion** is not a typical or classic feature of meningioma. **Analysis of incorrect options:** * **Vascular markings:** Meningiomas are highly vascular tumors, often supplied by the middle meningeal artery. On a skull X-ray, this manifests as enlargement of the grooves for the meningeal vessels (vascular markings) around the falx or convexity. * **Calcification:** This is a very common finding, seen in approximately 20–25% of cases. Histologically, this corresponds to the presence of **psammoma bodies**. * **Osteosclerosis (Hyperostosis):** This is a hallmark radiological sign. The tumor cells invade the Haversian canals of the adjacent bone, stimulating new bone formation. This results in reactive thickening and increased density of the bone overlying the tumor. **High-Yield Pearls for NEET-PG:** * **Dural Tail Sign:** A classic MRI finding (contrast enhancement of the thickened dura adjacent to the tumor). * **Sunburst/Spoke-wheel Appearance:** Seen on angiography due to the radial arrangement of feeding vessels. * **Most common location:** Parasagittal/Falcine. * **Association:** Neurofibromatosis Type 2 (NF2) – often presents with multiple meningiomas.

Question 173: A 55-year-old male presents with sudden onset of thunderclap headache followed by loss of consciousness for 4 hours. What is the initial investigation of choice?

A. Non-contrast CT followed by angiogram (Correct Answer)
B. PET scan
C. MRI angiogram
D. Contrast-enhanced CT

Explanation: **Explanation:** The clinical presentation of a **"thunderclap headache"** (sudden, maximal intensity "worst headache of life") followed by loss of consciousness is the classic hallmark of a **Subarachnoid Hemorrhage (SAH)**, most commonly due to a ruptured berry aneurysm. **1. Why Option A is Correct:** * **Non-Contrast CT (NCCT) Head:** This is the **initial investigation of choice** because it is highly sensitive (up to 98% in the first 24 hours) for detecting acute blood in the subarachnoid space. Blood appears hyperdense (white) on NCCT. * **Angiogram:** Once SAH is confirmed, the next step is to identify the source of bleeding (e.g., an aneurysm or AVM). **Digital Subtraction Angiography (DSA)** remains the gold standard, though CT Angiography (CTA) is often used first in clinical practice to plan surgical or endovascular intervention. **2. Why Other Options are Incorrect:** * **B. PET Scan:** Used for metabolic activity (oncology/dementia), not for acute vascular emergencies. * **C. MRI Angiogram:** While sensitive, MRI is time-consuming, less available in emergencies, and less sensitive than CT for acute hyperacute blood. * **D. Contrast-Enhanced CT (CECT):** Iodine contrast can mask the appearance of acute blood, as both appear white (hyperdense). NCCT is always preferred for suspected hemorrhage. **Clinical Pearls for NEET-PG:** * **Gold Standard for SAH diagnosis:** NCCT Head. * **If NCCT is negative but clinical suspicion is high:** Perform a **Lumbar Puncture** to look for xanthochromia (yellowish CSF due to bilirubin). * **Gold Standard for identifying the cause (Aneurysm):** Digital Subtraction Angiography (DSA). * **Most common site of Berry Aneurysm:** Anterior Communicating Artery (A-com).

Question 174: What is the best test to determine the etiology of subarachnoid hemorrhage (SAH)?

A. Enhanced CT scan
B. Unenhanced CT scan
C. Intra-arterial digital subtraction angiography (Correct Answer)
D. MRI

Explanation: **Explanation:** The gold standard for determining the **etiology** of a subarachnoid hemorrhage (SAH) is **Intra-arterial Digital Subtraction Angiography (DSA)**. While other modalities can detect the presence of blood, DSA provides the highest spatial resolution to identify the underlying vascular cause, such as a ruptured berry aneurysm (85% of cases), arteriovenous malformations (AVMs), or dural arteriovenous fistulas. It allows for 360-degree visualization and remains the definitive "map" for planning neurosurgical clipping or endovascular coiling. **Analysis of Options:** * **Unenhanced (Non-contrast) CT scan:** This is the **investigation of choice for the initial diagnosis** (detecting blood) of SAH, with nearly 100% sensitivity in the first 6–12 hours. However, it cannot reliably identify the specific etiology/source of the bleed. * **Enhanced CT scan:** Contrast-enhanced CT is generally avoided in the acute phase of SAH as the hyperdense contrast can be mistaken for or obscure the hyperdense acute blood. * **MRI:** While sensitive for subacute or chronic SAH (using FLAIR or SWI sequences), it is not the primary tool for determining etiology in the acute setting due to time constraints and lower resolution for small aneurysms compared to DSA. **Clinical Pearls for NEET-PG:** * **Initial Investigation of Choice:** Non-contrast CT (NCCT) Head. * **Gold Standard for Etiology:** Digital Subtraction Angiography (DSA). * **Most sensitive test if CT is negative:** Lumbar Puncture (looking for xanthochromia). * **Commonest site of Berry Aneurysm:** Anterior Communicating Artery (A-com). * **CT Angiography (CTA):** Often used as the first-line non-invasive vascular study, but DSA remains the definitive "best test."

Question 175: In herpes encephalitis, all of the following are true, except?

A. Focal symptoms are common
B. The temporal lobe is involved
C. MRI is diagnostic
D. CT scan is better than MRI (Correct Answer)

Explanation: ### Explanation **Herpes Simplex Encephalitis (HSE)** is the most common cause of fatal sporadic viral encephalitis. The core concept to remember for NEET-PG is that **MRI is the gold standard** and the investigation of choice, making Option D the incorrect statement (and thus the correct answer). #### Why Option D is the Correct Answer (The Exception) MRI is significantly more sensitive and specific than CT for HSE. CT scans are often **normal** in the first 3–5 days of the disease. Even when abnormalities appear on CT, they are often subtle (low-density lesions). MRI, particularly **Diffusion-Weighted Imaging (DWI)** and **T2/FLAIR** sequences, can detect changes within hours of symptom onset. #### Analysis of Other Options * **A. Focal symptoms are common:** HSE typically presents with acute onset of fever, headache, and focal neurological deficits (e.g., aphasia, hemiparesis) or focal seizures, reflecting its localized nature in the brain. * **B. The temporal lobe is involved:** HSE has a pathognomonic predilection for the **limbic system**. It characteristically involves the medial temporal lobes, insular cortex, and inferior frontal lobes. * **C. MRI is diagnostic:** MRI is the imaging modality of choice. It shows characteristic T2/FLAIR hyperintensity and restricted diffusion in the temporal lobes. While CSF PCR is the definitive "gold standard" for diagnosis, MRI is considered the "diagnostic" imaging modality. #### High-Yield Clinical Pearls for NEET-PG * **Etiology:** Usually caused by **HSV-1** in adults (reactivation in the trigeminal ganglion) and **HSV-2** in neonates. * **Imaging Sign:** Look for **"Sparing of the Basal Ganglia"**—this helps differentiate HSE from middle cerebral artery (MCA) infarcts. * **EEG Findings:** Periodic Lateralized Epileptiform Discharges (**PLEDs**) over the temporal lobes. * **Treatment:** Immediate IV **Acyclovir** should be started empirically if HSE is suspected, as delay increases mortality.

Question 176: All of the following calcify except –

A. Medulloblastoma (Correct Answer)
B. Sturge weber syndrome
C. Meningioma
D. Ependymoma

Explanation: **Explanation:** The correct answer is **Medulloblastoma**. In pediatric neuroradiology, intracranial calcification is a key differentiating feature. While medulloblastomas are highly cellular, "small round blue cell" tumors of the posterior fossa, they **rarely calcify (<10% of cases)**. They typically present as a midline mass arising from the roof of the 4th ventricle with homogenous enhancement. **Analysis of Options:** * **Sturge-Weber Syndrome:** Characterized by classic **"tram-track" calcifications**. These are cortical/subcortical gyriform calcifications caused by chronic ischemia underlying a leptomeningeal angioma. * **Meningioma:** These are the most common extra-axial tumors in adults. Calcification is a hallmark feature (seen in ~20-25% of cases), often appearing as **psammomatous bodies** (sand-like calcifications) on histopathology. * **Ependymoma:** In contrast to medulloblastoma, ependymomas (which arise from the floor of the 4th ventricle) calcify very frequently (**~50% of cases**). They are often described as "plastic" tumors because they squeeze through the foramina of Luschka and Magendie. **High-Yield Clinical Pearls for NEET-PG:** 1. **Rule of Thumb for Posterior Fossa:** If a midline pediatric tumor calcifies, think **Ependymoma**; if it doesn't, think **Medulloblastoma**. 2. **Most common calcified brain tumor:** Craniopharyngioma (90% calcify in children). 3. **Most common calcified intra-axial tumor in adults:** Oligodendroglioma ("Chicken-wire" vascularity and 70-90% calcification). 4. **Physiological Calcifications:** Pineal gland (>10 years), Habenular commissure, and Choroid plexus.

Question 177: What is characterized by a "puff of smoke" appearance?

A. Joubert syndrome
B. Moya Moya disease (Correct Answer)
C. Both Joubert syndrome and Moya Moya disease
D. Neither Joubert syndrome nor Moya Moya disease

Explanation: **Explanation:** **Moya Moya Disease (Correct Answer):** The term "Moya Moya" is Japanese for **"puff of smoke."** This characteristic angiographic appearance is caused by the formation of a fragile network of collateral vessels (lenticulostriate and thalamoperforating arteries) at the base of the brain. These collaterals develop to compensate for the progressive stenosis or occlusion of the terminal portions of the internal carotid arteries (ICA) and the commencement of the circle of Willis. On a conventional angiogram or MRA, these tiny, hazy vessels resemble a cloud or a puff of smoke. **Why other options are incorrect:** * **Joubert Syndrome:** This is a rare genetic neurodevelopmental disorder characterized by the agenesis or hypoplasia of the cerebellar vermis. Its classic radiological hallmark is the **"Molar Tooth Sign"** on axial MRI, caused by elongated superior cerebellar peduncles and a deepened interpeduncular fossa. It has no association with the "puff of smoke" appearance. * **Options C and D:** These are incorrect as the finding is pathognomonic specifically for Moya Moya disease. **High-Yield NEET-PG Pearls:** * **Bimodal Age Distribution:** Moya Moya typically affects children (presenting with ischemic stroke/TIA) and adults in their 30s-40s (presenting with hemorrhagic stroke). * **Ivy Sign:** On FLAIR MRI, slow-moving retrograde flow in leptomeningeal collaterals results in linear high signal intensity in the sulci, resembling ivy creeping on a wall. * **Treatment:** Surgical revascularization (e.g., EDAS or STA-MCA bypass) is the definitive management.

Question 178: Agenesis of cerebellar vermis, large posterior fossa with megacisterna magna is a feature of which condition?

A. Von Hippel-Lindau syndrome
B. Sturge Weber syndrome
C. Chiari malformation
D. Dandy Walker malformation (Correct Answer)

Explanation: ### Explanation **Dandy-Walker Malformation (DWM)** is a congenital posterior fossa anomaly characterized by a specific triad of radiological findings: 1. **Agenesis or hypoplasia of the cerebellar vermis** (the most critical feature). 2. **Cystic dilatation of the fourth ventricle**, which communicates with the posterior fossa. 3. **Enlarged posterior fossa** with upward displacement of the tentorium cerebelli and transverse sinuses (torcular-lambdoid inversion). The "megacisterna magna" appearance mentioned in the question refers to the massive fluid-filled space in the posterior fossa resulting from these malformations. #### Why the other options are incorrect: * **A. Von Hippel-Lindau (VHL) syndrome:** An autosomal dominant multisystem disorder characterized by visceral cysts and tumors. In the CNS, it is classically associated with **hemangioblastomas** (often in the cerebellum), not structural agenesis. * **B. Sturge-Weber syndrome:** A neurocutaneous syndrome (phakomatosis) characterized by a facial port-wine stain and **leptomeningeal angiomatosis**, typically leading to "tram-track" cortical calcifications and cerebral atrophy, not posterior fossa cysts. * **C. Chiari malformation:** These involve displacement of cerebellar structures through the foramen magnum. **Chiari I** involves tonsillar herniation (>5mm), while **Chiari II** involves herniation of the vermis and brainstem, usually associated with a **small** posterior fossa and myelomeningocele. #### High-Yield Clinical Pearls for NEET-PG: * **Dandy-Walker Variant:** A milder form where the posterior fossa size is normal, but there is partial vermian hypoplasia. * **Classic Sign:** On a sagittal MRI, look for the "keyhole" appearance of the fourth ventricle. * **Associated Finding:** Hydrocephalus is present in approximately 80% of DWM cases at birth or shortly after. * **Differential:** **Blake’s Pouch Cyst** also presents with a posterior fossa cyst but features a *normal* vermis.

Question 179: A comatose road traffic accident patient presents with a unilaterally dilated pupil. NCCT of the head reveals a peripheral lesion with a concavo-convex border. What is the probable diagnosis?

A. Subdural hematoma (Correct Answer)
B. Epidural hematoma
C. Subarachnoid hemorrhage
D. Intraparenchymal bleeding

Explanation: ### Explanation The correct diagnosis is **Subdural Hematoma (SDH)**. **1. Why Subdural Hematoma is correct:** The key radiological descriptor is the **"concavo-convex"** (crescent-shaped) border. An SDH occurs due to the tearing of **bridging cortical veins** as they cross the subdural space to drain into the dural sinuses. Because the subdural space is a potential space not limited by cranial sutures, the blood spreads extensively along the inner table of the skull, following the curve of the brain, resulting in a crescentic shape. The unilaterally dilated pupil indicates **uncal herniation** (compression of the ipsilateral CN III), a common complication of the mass effect caused by a large SDH. **2. Why other options are incorrect:** * **Epidural Hematoma (EDH):** Characterized by a **biconvex or lenticular** (lemon-shaped) appearance. It is caused by arterial bleeding (usually the Middle Meningeal Artery) and is limited by cranial sutures where the dura is firmly attached. * **Subarachnoid Hemorrhage (SAH):** Typically appears as hyperdensity within the **sulci, fissures, and basal cisterns** (often described as a "star-shaped" density in the circle of Willis), rather than a peripheral collection. * **Intraparenchymal bleeding:** This occurs **within the brain tissue** itself (white or gray matter) and does not follow the peripheral borders of the skull. **3. NEET-PG High-Yield Pearls:** * **SDH Shape:** Crescentic / Concavo-convex (Crosses suture lines). * **EDH Shape:** Lenticular / Biconvex (Does **not** cross suture lines). * **Source of Bleed:** SDH = Bridging Veins; EDH = Middle Meningeal Artery. * **Chronic SDH:** Appears **hypodense** (dark) on NCCT, whereas acute SDH is **hyperdense** (bright). * **Clinical Sign:** A unilaterally dilated, non-reactive pupil in head trauma is a neurosurgical emergency indicating impending transtentorial herniation.

Question 180: On non-contrast computed tomography (NCCT) of the head, what is the typical appearance of an extradural hemorrhage?

A. Hyperdense biconvex (Correct Answer)
B. Hypodense biconcave
C. Hyperdense biconcave
D. Hypodense biconvex

Explanation: ### Explanation **Correct Option: A. Hyperdense biconvex** **Why it is correct:** An **Extradural Hemorrhage (EDH)**, also known as an epidural hematoma, typically results from the rupture of the **middle meningeal artery** (often due to a temporal bone fracture). On NCCT, acute blood appears **hyperdense** (bright white) because of the high hemoglobin concentration. The blood collects between the inner table of the skull and the tough dural layer. Because the dura is firmly attached to the cranial sutures, the expanding hematoma is confined, forcing it to bulge inward into a characteristic **biconvex (lentiform or lens-shaped)** shape. Crucially, EDH **does not cross suture lines** but can cross the midline (dural folds). **Why other options are incorrect:** * **B & D (Hypodense):** Acute blood is hyperdense. Hypodensity in a hematoma usually indicates an older, chronic stage (liquefaction) or the "swirl sign" (active hyperacute bleeding), which is not the "typical" acute presentation. * **C (Biconcave):** A biconcave or **crescentic** shape is the hallmark of a **Subdural Hemorrhage (SDH)**. SDH occurs due to the tearing of bridging veins; since the subdural space is a potential space not limited by sutures, the blood spreads thinly along the brain's convexity. **High-Yield Clinical Pearls for NEET-PG:** * **Clinical Presentation:** Classically associated with a **"Lucid Interval"** (initial loss of consciousness → temporary recovery → rapid deterioration). * **Source of Bleed:** 90% are arterial (Middle Meningeal Artery); 10% are venous (Dural venous sinuses). * **Management:** Large or symptomatic EDHs are surgical emergencies requiring urgent **craniotomy and evacuation**. * **Imaging Rule:** EDH = Lens-shaped/Biconvex; SDH = Banana-shaped/Crescentic.

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