Neuroradiology Practice Questions

Q: What is the investigation of choice for meningeal carcinomatosis?

Contrast-enhanced MRI. **Explanation:** **Meningeal carcinomatosis** (Leptomeningeal carcinomatosis) refers to the infiltration of the subarachnoid space by malignant cells from solid tumors (most commonly breast, lung, and melanoma). **Why Contrast-enhanced MRI (CE-MRI) is the Investigation of Choice:** MRI with gadolinium contrast is the most sensitive imaging modality for detecting leptomeningeal spread. The hallmark finding is **"sugar-coating" (Zuckerguss)**, characterized by linear or nodular enhancement along the sulci, cisterns, and cranial nerves. MRI is superior to CT because of its higher soft-tissue contrast and ability to visualize the posterior fossa and spinal cord, where malignant cells often settle due to gravity. **Analysis of Incorrect Options:** * **PET-CT:** While useful for identifying the primary systemic malignancy, it lacks the spatial resolution required to detect thin, microscopic layers of tumor cells along the meninges. * **SPECT:** This is a functional imaging tool primarily used for brain perfusion or differentiating radiation necrosis from tumor recurrence; it has no role in diagnosing meningeal carcinomatosis. * **Non-contrast CT (NCCT):** NCCT is highly insensitive for meningeal pathology. It may show secondary signs like hydrocephalus but will miss the actual carcinomatous infiltration. **Clinical Pearls for NEET-PG:** * **Gold Standard:** While CE-MRI is the *investigation of choice* (imaging), the **Gold Standard** for diagnosis remains **CSF Cytology** (demonstrating malignant cells). * **Imaging Pattern:** Look for "pial" or "leptomeningeal" enhancement that follows the contours of the brain gyri into the sulci. * **Common Primaries:** In adults, it is most common in Breast and Lung cancer; in children, it is seen with Medulloblastoma and Ependymoma (often called "drop metastases").

Q: A patient on warfarin presents with right-sided hemiplegia. What is the initial investigation of choice?

CT scan. **Explanation:** The patient presents with a focal neurological deficit (right-sided hemiplegia) while on **warfarin**, a potent anticoagulant. This clinical scenario strongly suggests an acute stroke, with a high suspicion of **Intracranial Hemorrhage (ICH)** due to the underlying coagulopathy. **Why CT scan is the correct answer:** A **Non-Contrast Computed Tomography (NCCT) Head** is the gold standard initial investigation for acute stroke. Its primary role is to **differentiate between ischemic and hemorrhagic stroke**. In this case, identifying a bleed is critical because the management involves immediate reversal of anticoagulation. CT is preferred over MRI in the emergency setting because it is faster, more widely available, and highly sensitive (nearly 100%) for detecting acute blood (which appears hyperdense/white). **Why other options are incorrect:** * **MRI:** While more sensitive for early ischemic changes (Diffusion-Weighted Imaging), it is time-consuming, less available, and more expensive. In an emergency "Time is Brain" scenario, CT is always the first step. * **Chest X-ray:** This is irrelevant for diagnosing an intracranial event. * **PET scan:** This is a functional imaging modality used primarily in oncology or epilepsy workups; it has no role in the acute management of stroke. **High-Yield Clinical Pearls for NEET-PG:** 1. **Hyperacute Stroke:** NCCT is done to rule out hemorrhage before considering thrombolysis. 2. **Appearance of Blood on CT:** Acute blood is **Hyperdense** (White). As it ages, it becomes Isodense and eventually Hypodense (Black). 3. **Warfarin Reversal:** If ICH is confirmed, the immediate treatment is Vitamin K and **Prothrombin Complex Concentrate (PCC)** or Fresh Frozen Plasma (FFP). 4. **"Door to CT" time:** Ideally should be less than 20–25 minutes in a stroke center.

Q: CT scan is complementary to MRI in which of the following conditions?

Posterior fossa tumor. In neuroradiology, MRI is the gold standard for evaluating the posterior fossa due to its superior soft-tissue contrast and lack of **"beam-hardening artifacts"** from the surrounding dense petrous and occipital bones, which often obscure details on CT. However, CT is considered **complementary** [1], [3] in **Posterior Fossa Tumors** [1] because it excels at identifying **calcification** [3] (e.g., in ependymomas) and **bony erosion or hyperostosis** [1], [2] (e.g., in acoustic neuromas or meningiomas). While MRI defines the tumor's extent and relationship to neural structures, CT provides critical information regarding the mineralized components and skull base involvement [1], [2]. **Analysis of Incorrect Options:** * **Trauma:** CT is the **initial investigation of choice** (not just complementary) because it is rapid and highly sensitive for acute intracranial hemorrhage and skull fractures. * **Hydrocephalus:** CT is often the primary modality for quick diagnosis and monitoring of ventricular size. While MRI helps identify the cause (e.g., aqueductal stenosis), CT is usually sufficient for management. * **Vascular Lesions:** For acute stroke, CT is the first-line tool to rule out hemorrhage. For detailed vascular anatomy (aneurysms/AVMs), **Digital Subtraction Angiography (DSA)** remains the gold standard, with MRA/CTA being the primary non-invasive choices. **High-Yield Clinical Pearls:** * **Beam Hardening Artifact:** The primary reason CT is inferior to MRI for the posterior fossa. * **Calcification:** CT is more sensitive than standard MRI sequences for detecting calcium [3]. * **Modality of Choice:** MRI is the best overall for posterior fossa, but CT is the "complementary" tool for bone/calcification details [3].

Q: The MR imaging in multiple sclerosis will show lesions in which of the following locations?

White matter. **Explanation:** **Multiple Sclerosis (MS)** is a chronic, immune-mediated inflammatory demyelinating disease of the Central Nervous System (CNS). The hallmark of MS is the presence of demyelinating plaques, which primarily target the **myelin sheath** produced by oligodendrocytes. **Why White Matter is Correct:** Myelin is the primary constituent of the CNS **white matter**. Therefore, MS lesions (plaques) are characteristically found in white matter tracts. On MRI, these appear as hyperintense lesions on T2-weighted and FLAIR sequences. Classic locations include the **periventricular** region (Dawson’s fingers), juxtacortical areas, infratentorial region (brainstem/cerebellum), and the spinal cord. **Why Other Options are Incorrect:** * **Grey Matter, Thalamus, and Basal Ganglia:** While modern high-field MRI (7T) has shown that "grey matter involvement" can occur in advanced MS, it is not the classic or primary site of pathology. For examination purposes, MS is strictly defined as a **White Matter Disease**. The Thalamus and Basal Ganglia are deep grey matter structures and are not the primary diagnostic sites for MS lesions. **High-Yield Clinical Pearls for NEET-PG:** * **Dawson’s Fingers:** Ovoid demyelinating plaques oriented perpendicular to the lateral ventricles (representing perivenular inflammation). * **McDonald Criteria:** The current gold standard for diagnosis, requiring "Dissemination in Space" (DIS) and "Dissemination in Time" (DIT). * **MRI Sequence of Choice:** **FLAIR** (Fluid Attenuated Inversion Recovery) is best for visualizing periventricular lesions as it suppresses the bright CSF signal. * **Active Lesions:** Show **Gadolinium enhancement** on T1-weighted images, indicating acute blood-brain barrier breakdown.

Q: What is the characteristic CT scan finding of an extradural hematoma?

Hyperdense biconvex lesion. ### Explanation **1. Why Option B is Correct:** An **Extradural Hematoma (EDH)** typically results from an arterial bleed (most commonly the **middle meningeal artery**) following a skull fracture. On a Non-Contrast CT (NCCT) scan, acute blood appears **hyperdense** (bright white) due to high hemoglobin concentration. The blood collects between the inner table of the skull and the endosteal layer of the dura. Because the dura is firmly attached to the cranial sutures, the hematoma is confined, resulting in a characteristic **biconvex (lentiform or lemon-shaped)** appearance. Unlike subdural bleeds, EDHs do not cross suture lines. **2. Why Other Options are Incorrect:** * **Option A & D:** Acute blood is never hypodense or low-attenuated. **Hypodensity** in a hematoma usually indicates a chronic stage (liquefaction) or an active "swirl sign" (hyperacute bleeding), but the classic presentation of EDH is hyperdense. * **Option C:** A **concavo-convex (crescentic or banana-shaped)** lesion is the hallmark of a **Subdural Hematoma (SDH)**. SDHs occur in the potential space between the dura and arachnoid mater and can cross suture lines because they are not restricted by dural attachments. **3. Clinical Pearls for NEET-PG:** * **Lucid Interval:** A classic clinical feature where the patient regains consciousness after initial trauma before deteriorating again. * **Source of Bleed:** Middle meningeal artery (most common) or dural venous sinuses (in children). * **Anatomical Landmark:** Most EDHs occur in the **pterion** region (temporal bone). * **Suture Rule:** EDH **cannot** cross suture lines but **can** cross dural reflections (like the falx or tentorium). SDH is the opposite.

Q: Feeding a nidus is characteristic of which of the following?

True arteriovenous malformation. ### Explanation **Correct Answer: A. True arteriovenous malformation** **Underlying Concept:** A **True Arteriovenous Malformation (AVM)** is a high-flow vascular anomaly characterized by a direct communication between arteries and veins without an intervening capillary bed. The hallmark of an AVM is the **nidus**—a tangled network of dysplastic vascular channels. In this circuit, "feeding arteries" deliver high-pressure blood directly into the nidus, which then drains into "enlarged arterialized veins." The presence of a nidus is the defining pathological and radiological feature that distinguishes true AVMs from other vascular malformations. **Why incorrect options are wrong:** * **Venous Angioma (Developmental Venous Anomaly):** These are low-flow lesions consisting of a "caput medusae" appearance (radially arranged veins) draining into a single large collector vein. There is no arterial nidus. * **Cavernous Angioma (Cavernoma):** These are "angiographically occult" low-flow lesions consisting of dilated, thin-walled sinusoids (caverns) lined by endothelium. They lack both a nidus and large feeding/draining vessels. * **Hemangioma:** These are true vascular tumors (neoplasms) characterized by endothelial proliferation, rather than a structural malformation of the arteriovenous junction. **NEET-PG High-Yield Pearls:** * **Gold Standard Investigation:** Digital Subtraction Angiography (DSA) is the gold standard for visualizing the nidus and flow dynamics of an AVM. * **MRI Appearance:** AVMs typically show a "bag of worms" appearance with multiple punctate and curvilinear **flow voids** on T1 and T2 weighted images. * **Clinical Presentation:** The most common presentation is intracranial hemorrhage (ICH) or seizures. * **Spetzler-Martin Grading:** Used to assess surgical risk based on nidus size, eloquence of adjacent brain, and venous drainage pattern.

Q: What is the commonest cause of obstructive hydrocephalus in children?

Acqueductal stenosis. **Explanation:** **Obstructive (Non-communicating) Hydrocephalus** occurs when there is a physical blockage to the flow of Cerebrospinal Fluid (CSF) within the ventricular system. **Aqueductal Stenosis (Option A)** is the most common cause of congenital obstructive hydrocephalus in children. The Aqueduct of Sylvius (connecting the 3rd and 4th ventricles) is the narrowest point in the CSF pathway, making it highly susceptible to narrowing. It can be idiopathic, X-linked (L1CAM mutation), or due to extrinsic compression (e.g., pineal tumors). On imaging, it typically shows dilatation of the lateral and third ventricles with a normal-sized fourth ventricle. **Why other options are incorrect:** * **Aqueductal Gliosis (Option B):** This is an acquired narrowing of the aqueduct usually following an intrauterine infection (like Toxoplasmosis or CMV) or hemorrhage. While it causes stenosis, idiopathic/congenital stenosis is statistically more common. * **Subarachnoid Hemorrhage (Option C) and Tubercular Meningitis (Option D):** These typically cause **Communicating (Non-obstructive) Hydrocephalus**. In these conditions, the blockage occurs at the level of the arachnoid villi, preventing the reabsorption of CSF into the venous sinuses, rather than obstructing the flow within the ventricles. **High-Yield Clinical Pearls for NEET-PG:** * **Most common cause of hydrocephalus in infants:** Aqueductal stenosis. * **Triventricular Hydrocephalus:** Classic imaging finding in aqueductal stenosis (Dilated 1st, 2nd, and 3rd ventricles). * **Bickers-Adams Syndrome:** X-linked aqueductal stenosis associated with thumb adduction and intellectual disability. * **Treatment of choice:** Endoscopic Third Ventriculostomy (ETV) or VP Shunt.

Question 1

What is the investigation of choice for meningeal carcinomatosis?

Accepted Answer

Contrast-enhanced MRI

Answer

PET-CT

Answer

SPECT

Answer

Non-contrast CT (NCCT)

Question 2

A patient on warfarin presents with right-sided hemiplegia. What is the initial investigation of choice?

Accepted Answer

CT scan

Answer

Chest X-ray

Answer

MRI

Answer

PET scan

Question 3

CT scan is complementary to MRI in which of the following conditions?

Accepted Answer

Posterior fossa tumor

Answer

Trauma

Answer

Hydrocephalus

Answer

Vascular lesion

Question 4

A 64-year-old man presents with headache and left-sided upper extremity weakness. The MRI findings suggest that this is a glioblastoma multiforme. This is because the tumor exhibits which of the following characteristics?

Accepted Answer

Ring pattern of enhancement with intravenous contrast and a non-enhancing necrotic center.

Answer

Regular shape.

Answer

Well demarcated from surrounding brain tissue.

Answer

Absence of surrounding white-matter edema.

Question 5

The MR imaging in multiple sclerosis will show lesions in which of the following locations?

Accepted Answer

White matter

Answer

Grey matter

Answer

Thalamus

Answer

Basal ganglia

Question 6

What is the characteristic CT scan finding of an extradural hematoma?

Accepted Answer

Hyperdense biconvex lesion

Answer

Hypodense biconvex lesion

Answer

Concavo-convex hyperdense lesion

Answer

Low attenuated biconvex lesion

Question 7

Feeding a nidus is characteristic of which of the following?

Accepted Answer

True arteriovenous malformation

Answer

Venous angioma

Answer

Cavernous angioma

Answer

Hemangioma

Question 8

A patient presents with symptoms of sudden headache and paralysis. A CT scan reveals a subarachnoid hemorrhage. What is the next investigation of choice?

Accepted Answer

4-vessel angiography

Answer

SPECT

Answer

Transorbital Doppler ultrasonography

Answer

MRI

Question 9

What is the commonest cause of obstructive hydrocephalus in children?

Accepted Answer

Acqueductal stenosis

Answer

Aqueductal gliosis

Answer

Subarachnoid hemorrhage

Answer

Tubercular meningitis

Question 10

Which epileptic syndrome is associated with left hemispheric atrophy in a child?

Accepted Answer

Dyke Davidson Masson syndrome

Answer

Dravet Syndrome

Answer

Lennox Gastaut syndrome

Answer

West Syndrome

Neuroradiology — MCQs

Neuroradiology — MCQs

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