Neuroradiology Practice Questions

Q: What is the best imaging modality for the diagnosis of tubercular meningitis?

Contrast-enhanced MRI (CE-MRI). **Explanation:** **1. Why Contrast-enhanced MRI (CE-MRI) is the Correct Answer:** MRI is the gold standard for neuroimaging in Tubercular Meningitis (TBM) due to its superior soft-tissue contrast and multiplanar imaging capabilities. The hallmark of TBM is **thick, gelatinous basal exudates**. CE-MRI is highly sensitive in detecting **intense leptomeningeal enhancement**, especially within the basal cisterns (Sylvian fissures, perimesencephalic, and suprasellar cisterns). Furthermore, MRI is far superior to CT in identifying early complications such as small infarcts (due to vasculitis), cranial nerve involvement, and early-stage tuberculomas. **2. Why the Incorrect Options are Wrong:** * **Contrast-enhanced CT (CE-CT):** While often the first investigation performed in emergency settings to rule out hydrocephalus, CT has lower sensitivity for detecting subtle meningeal enhancement and posterior fossa pathology compared to MRI. * **PET and SPECT:** These are functional imaging modalities. While PET may be used to identify extracranial systemic tuberculosis or differentiate a tuberculoma from a malignancy in ambiguous cases, they play no role in the primary diagnosis of meningitis. **3. NEET-PG High-Yield Clinical Pearls:** * **Classic Triad on Imaging:** 1. Basal meningeal enhancement, 2. Hydrocephalus (usually communicating), and 3. Infarcts (most common in the "Medial Striate" and "Thalamoperforating" arteries, leading to basal ganglia infarcts). * **Tuberculoma Appearance:** On MRI, a "mature" tuberculoma often shows a **"Target Sign"** (central calcification or necrosis with peripheral enhancement). * **Most Common Complication:** Hydrocephalus is the most frequent complication of TBM in children. * **Gold Standard for Diagnosis:** While MRI is the best *imaging* modality, the definitive gold standard remains CSF analysis (demonstrating AFB on smear/culture or positive GeneXpert).

Q: Which is the most common intraparenchymal brain tumor to show calcification?

Oligodendroglioma. **Explanation:** **Oligodendroglioma** is the correct answer because it is the most common **intraparenchymal** (within the brain tissue) tumor to exhibit calcification. Radiologically, calcification is seen in approximately **70–90%** of these cases. These tumors typically present as cortical or subcortical masses, most frequently in the **frontal lobe**, and often cause seizures. On CT scans, the calcifications are often described as "clumped" or "ribbon-like." **Analysis of Incorrect Options:** * **Meningioma (Option A):** While meningiomas very frequently show calcification (psammoma bodies), they are **extraparenchymal** (arising from the meninges) rather than intraparenchymal. * **Astrocytoma (Option C):** Low-grade astrocytomas can calcify, but the frequency is much lower (approx. 15–20%) compared to oligodendrogliomas. Glioblastoma Multiforme (GBM) rarely shows calcification unless there is a prior lower-grade lesion. * **Ependymoma (Option D):** These frequently calcify (about 50% of cases), but they are typically **intraventricular** or periventricular in location rather than purely intraparenchymal. **High-Yield NEET-PG Pearls:** * **Genetic Marker:** Oligodendrogliomas are strongly associated with the **1p/19q co-deletion**, which predicts a better response to chemotherapy. * **Imaging Sign:** On MRI, they often show a "cortical expansion" look. * **Most common calcified tumor in children:** Craniopharyngioma (suprasellar location). * **Most common posterior fossa tumor to calcify:** Ependymoma. * **Rule of Thumb:** If a question asks for the most common *intraparenchymal* calcified tumor in an adult, always think **Oligodendroglioma**.

Q: What is the most common extra-axial intracranial tumor?

Meningioma. **Explanation:** **Meningioma** is the correct answer as it is the most common primary intracranial tumor overall and the most frequent **extra-axial** tumor, accounting for approximately 35–40% of all adult brain tumors. These tumors arise from the arachnoid cap cells of the arachnoid villi. On imaging, they typically present as well-circumscribed, dural-based masses that show intense, homogenous enhancement and often exhibit the "dural tail sign." **Analysis of Incorrect Options:** * **Schwannoma:** While these are common extra-axial tumors (especially Vestibular Schwannomas at the cerebellopontine angle), they are significantly less frequent than meningiomas. * **Lipoma:** These are rare, congenital malformations (not true neoplasms) often found near the midline, such as the corpus callosum. * **Arachnoid Cyst:** These are benign, CSF-filled sacs. While they are common extra-axial "lesions," they are developmental cysts rather than tumors. **High-Yield Clinical Pearls for NEET-PG:** * **Demographics:** More common in females (2:1 ratio) due to progesterone receptors on the tumor cells. * **Imaging Hallmarks:** Look for the **"Dural Tail Sign"** (thickening of adjacent dura) and **"CSF Cleft Sign"** (displaced CSF/vessels between the tumor and brain parenchyma, confirming its extra-axial location). * **Histology:** The classic finding is **Psammoma bodies** (laminated calcifications) and whorled patterns of cells. * **Associations:** Multiple meningiomas are strongly associated with **Neurofibromatosis Type 2 (NF2)**. * **Hyperostosis:** Meningiomas often cause reactive thickening of the overlying bone, a key diagnostic feature on CT.

Q: What is the gold standard investigation for cerebral arteriovenous malformation?

Cerebral Angiography. **Explanation:** **Cerebral Angiography (Digital Subtraction Angiography - DSA)** is the gold standard for diagnosing and evaluating cerebral arteriovenous malformations (AVMs). The underlying medical concept relies on its superior **temporal and spatial resolution**. AVMs are high-flow vascular shunts; DSA allows for real-time visualization of the "nidus," identification of specific arterial feeders, and detection of early venous drainage. It is essential for treatment planning (surgery, embolization, or radiosurgery) as it can identify high-risk features like intranidal aneurysms. **Why other options are incorrect:** * **DWI MRI scan:** Diffusion-Weighted Imaging is the gold standard for detecting **acute ischemic stroke** (cytotoxic edema), not vascular malformations. * **CT scan:** While a Non-Contrast CT (NCCT) is the initial investigation of choice to rule out **acute intracranial hemorrhage** (a common complication of AVMs), it cannot delineate the vascular architecture of the malformation itself. * **MRI scan:** MRI (specifically T2/FLAIR sequences) is excellent for showing the "honeycomb" appearance or "bag of black worms" (flow voids), but it lacks the hemodynamic detail provided by DSA. **High-Yield Clinical Pearls for NEET-PG:** * **Classic Sign:** On MRI, AVMs typically show **"Flow Voids"** due to rapidly moving blood. * **Spetzler-Martin Grading:** Used to estimate surgical risk based on size, eloquence of adjacent brain tissue, and venous drainage pattern. * **Most common presentation:** Intracranial hemorrhage (30-50%) followed by seizures. * **Gold Standard for Aneurysm/AVM:** Always Digital Subtraction Angiography (DSA).

Q: The "bare orbit" sign is characteristic of which of the following conditions?

Neurofibromatosis type 1 (NF-1). The **"Bare Orbit" sign** is a classic radiological hallmark of **Neurofibromatosis type 1 (NF-1)**. ### **1. Why NF-1 is Correct** The sign is caused by **sphenoid wing dysplasia** (specifically the absence or hypoplasia of the greater wing of the sphenoid). On a frontal skull radiograph or CT, the absence of the sphenoid wing removes the normal bony boundary between the middle cranial fossa and the orbit. This results in an empty-appearing orbit (the "bare orbit") and leads to **pulsatile exophthalmos**, as the pulsations of the cerebrospinal fluid (CSF) are transmitted directly to the orbital contents. ### **2. Why Other Options are Incorrect** * **Neurofibromatosis type 2 (NF-2):** Characterized by "MISME" (Multiple Inherited Schwannomas, Meningiomas, and Ependymomas), most notably bilateral vestibular schwannomas. It does not typically involve sphenoid wing dysplasia. * **Schwannoma:** While NF-1 is associated with neurofibromas, isolated schwannomas do not cause the structural bony defects required to produce the bare orbit sign. * **Ependymoma:** These are glial tumors (commonly found in the fourth ventricle or spinal cord in NF-2) and have no association with orbital bony dysplasia. ### **3. High-Yield Clinical Pearls for NEET-PG** * **Lisch Nodules:** Iris hamartomas (most common ocular finding in NF-1). * **Optic Nerve Glioma:** The most common visceral tumor in NF-1. * **Buphthalmos:** Congenital glaucoma (enlarged eye) often seen in NF-1. * **Radiology Tip:** If you see a "bare orbit" on a CT scan, also look for a **plexiform neurofibroma** (described as a "bag of worms" appearance) in the adjacent soft tissues.

Q: Which of the following is the most vascular tumor?

Meningioma. **Explanation:** **Meningioma** is the correct answer because it is a highly vascular, extra-axial tumor that derives its blood supply primarily from the **external carotid artery (ECA)**, specifically the middle meningeal artery. On angiography, meningiomas classically demonstrate a **"Sunburst" or "Spoked-wheel" appearance** of the feeding vessels and a prolonged, intense **"Mother-in-law blush"** (starts early, stays late). **Analysis of Incorrect Options:** * **Glioblastoma (GBM):** While GBM is characterized by significant neo-angiogenesis and "vascular endothelial proliferation," it is an intra-axial tumor. Its vascularity is often disorganized with areas of central necrosis, unlike the uniform, intense enhancement seen in meningiomas. * **Epidermoid Tumor:** These are "pearly tumors" that are **avascular**. On MRI, they are characteristically T1-hypointense, T2-hyperintense, and show **restricted diffusion on DWI**, but they do not enhance with contrast. * **Neurocytoma:** Central neurocytomas are intraventricular tumors. While they show moderate vascularity (often with a "soap-bubble" appearance on imaging), they do not reach the hypervascularity levels of a meningioma. **High-Yield Clinical Pearls for NEET-PG:** * **Dural Tail Sign:** A classic MRI finding in meningioma (though not pathognomonic). * **Psammoma Bodies:** Histological hallmark representing laminated calcifications. * **Hyperostosis:** Meningiomas often cause thickening of the overlying bone. * **Most common site:** Parasagittal/falcine region. * **Association:** Neurofibromatosis Type 2 (NF2) is associated with multiple meningiomas.

Question 1

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 2

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

Question 3

What is the best imaging modality for the diagnosis of tubercular meningitis?

Accepted Answer

Contrast-enhanced MRI (CE-MRI)

Answer

Contrast-enhanced CT (CE-CT)

Answer

Positron Emission Tomography (PET)

Answer

Single-photon emission computed tomography (SPECT)

Question 4

Which is the most common intraparenchymal brain tumor to show calcification?

Accepted Answer

Oligodendroglioma

Answer

Meningioma

Answer

Astrocytoma

Answer

Ependymoma

Question 5

What is the most common extra-axial intracranial tumor?

Accepted Answer

Meningioma

Answer

Schwannoma

Answer

Lipoma

Answer

Arachnoid cyst

Question 6

What is the diagnostic test of choice for cerebral cysticercosis?

Accepted Answer

Non-contrast CT scan

Answer

MRI

Answer

Contrast CT scan

Answer

Plain X-ray

Question 7

What is the gold standard investigation for cerebral arteriovenous malformation?

Accepted Answer

Cerebral Angiography

Answer

DWI MRI scan

Answer

CT scan

Answer

MRI scan

Question 8

Which of the following statements regarding cerebral microbleeds (CMBs) is FALSE?

Accepted Answer

They are seen as small areas of hypointensity on T2-weighted brain MRI imaging.

Answer

Lobar CMBs are likely associated with cerebral amyloid angiopathy.

Answer

Hypertension is a common etiology.

Answer

They can contribute to cognitive decline.

Question 9

The "bare orbit" sign is characteristic of which of the following conditions?

Accepted Answer

Neurofibromatosis type 1 (NF-1)

Answer

Neurofibromatosis type 2 (NF-2)

Answer

Schwannoma

Answer

Ependymoma

Question 10

Which of the following is the most vascular tumor?

Accepted Answer

Meningioma

Answer

Glioblastoma

Answer

Epidermoid tumor

Answer

Neurocytoma

Neuroradiology — MCQs

Neuroradiology — MCQs

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