Neuroradiology Practice Questions

Q: What is the best imaging investigation for parameningeal rhabdomyosarcoma?

Magnetic resonance imaging (MRI). **Explanation:** **1. Why MRI is the Correct Answer:** Magnetic Resonance Imaging (MRI) is the gold standard for evaluating parameningeal rhabdomyosarcoma (RMS) due to its **superior soft-tissue contrast**. Parameningeal sites (e.g., nasopharynx, infratemporal fossa, paranasal sinuses) are anatomically complex. MRI is essential to assess **perineural spread**, intracranial extension, and involvement of the skull base or cavernous sinus. It provides better visualization of the tumor's relationship with the dura and brain parenchyma compared to CT. **2. Why Other Options are Incorrect:** * **CECT (Option C):** While CT is excellent for detecting bone erosion (destruction of the skull base), it lacks the soft-tissue resolution required to differentiate the tumor from adjacent muscles, nerves, or intracranial structures. It is often used as an adjunct, not the primary investigation. * **CSF Cytology (Option A):** This is used to detect leptomeningeal spread (seeding into the spinal fluid) but is a staging procedure, not the primary imaging investigation for the tumor itself. * **PET Scan (Option D):** PET is valuable for detecting distant metastases and monitoring treatment response (systemic staging), but it does not provide the anatomical detail necessary for local surgical or radiation planning. **3. High-Yield Clinical Pearls for NEET-PG:** * **Parameningeal Sites:** These carry the **worst prognosis** among head and neck RMS due to the high risk of meningeal involvement. * **Imaging Choice:** For any pediatric soft tissue sarcoma of the head and neck, **MRI with Gadolinium** is the investigation of choice. * **Classic Presentation:** A child presenting with a rapidly enlarging mass, cranial nerve palsies, or chronic "sinusitis" that doesn't resolve. * **Management:** Multimodal approach involving chemotherapy, surgery, and radiation.

Q: In cerebral infarct, maximum enhancement on a CT scan is typically seen after how many days?

14 days. **Explanation:** The correct answer is **14 days (Option D)**. This phenomenon is governed by the physiological timeline of the **Blood-Brain Barrier (BBB) breakdown** and subsequent **neovascularization**. 1. **Why 14 days is correct:** Following a cerebral infarct, the BBB begins to break down within the first few days. However, maximal enhancement (often termed "luxury perfusion" or reactive angiogenesis) typically peaks during the **subacute phase**, specifically between **1 to 3 weeks**. On a CT scan, this enhancement is most prominent around **day 14**. This occurs because the newly formed capillaries in the granulation tissue lack tight junctions, allowing contrast to leak into the infarcted parenchyma. 2. **Why other options are incorrect:** * **2 days (Option A):** This is the acute phase. Enhancement is rare at this stage because the BBB is often still relatively intact, and cytotoxic edema predominates. * **5 days (Option B):** Enhancement begins to appear (starting around day 3), but it has not yet reached its peak intensity. * **9 days (Option C):** While enhancement is visible, it continues to increase in intensity throughout the second week, peaking closer to the 14-day mark. **High-Yield Clinical Pearls for NEET-PG:** * **"Fogging Effect":** Occurs between weeks 2 and 3 (around day 10–21). On non-contrast CT, the infarct may temporarily appear isodense to normal brain tissue because the resolution of edema and the presence of petechial hemorrhages "mask" the low density. * **Sequence of Enhancement:** Enhancement typically persists for 6–8 weeks before fading as the glial scar forms. * **Pattern:** Post-infarct enhancement is usually **gyral (cortical)** in distribution, following the ribbon of the gray matter. * **Rule of 3s:** Infarct enhancement starts at 3 days, peaks at 3 weeks (range 1–3), and disappears by 3 months. (Note: For MCQ purposes, 14 days is the standard "peak" answer).

Q: A patient with advanced HIV (CD4 count < 100) presents with headache and blurred vision for 15 days, and neck rigidity on examination. An MRI was performed. What is the most likely diagnosis?

Cryptococcosis. ***Cryptococcosis*** - **Advanced HIV** with **CD4 < 100** and **subacute meningoencephalitis** (15 days of headache, blurred vision, neck rigidity) are classic for **cryptococcal meningitis** - MRI typically shows **dilated Virchow-Robin spaces** and **gelatinous pseudocysts** in the **basal ganglia** on **T2/FLAIR** sequences, appearing as "soap bubble" lesions *Tuberculosis* - TB meningitis usually presents with **basilar enhancement** and **hydrocephalus** on MRI, not the characteristic pseudocysts seen in cryptococcosis - While common in HIV patients, the **subacute presentation** and specific MRI findings favor cryptococcosis over TB *CNS toxoplasmosis* - Typically presents with **multiple ring-enhancing lesions** with **surrounding edema** on contrast MRI, not pseudocysts - More commonly affects the **basal ganglia** and **frontal/parietal cortex** with characteristic "target sign" enhancement *CNS lymphoma* - Usually appears as **solitary** or few **homogeneously enhancing lesions** in **periventricular** or **corpus callosum** regions - Lacks the characteristic **soap bubble** appearance and **Virchow-Robin space dilatation** seen in cryptococcal infection

Q: Central T2 hypo intensity is a characteristic imaging feature of which of the following conditions?

Tuberculous granuloma with a solid center. **Explanation:** The imaging appearance of a **Tuberculoma (Tuberculous granuloma)** evolves through distinct pathological stages, which is a high-yield concept for NEET-PG. **1. Why Option B is Correct:** A **solid caseating tuberculoma** (solid center) is characterized by a dense collection of caseous necrosis. This solid material has relatively low water content and high cellular density, which leads to **shortened T2 relaxation times**. Consequently, it appears **hypointense (dark) on T2-weighted images**. This is a classic "radiology sign" used to differentiate it from most other ring-enhancing lesions (like neurocysticercosis or abscesses), which are typically T2 hyperintense. **2. Analysis of Incorrect Options:** * **Option A (Neurocysticercosis):** In the vesicular stage, the cyst fluid is similar to CSF (T2 hyperintense). In the colloidal stage, the fluid becomes turbid but remains relatively hyperintense compared to the solid core of a tuberculoma. * **Option C (Liquefied center):** As a tuberculoma matures, the solid center undergoes liquefaction. This increase in water content causes the center to become **T2 hyperintense**. * **Option D (Tubercular abscess):** These are larger, pus-filled cavities. Like pyogenic abscesses, the liquid pus is **T2 hyperintense** and shows marked restricted diffusion on DWI. **Clinical Pearls for NEET-PG:** * **T1 Imaging:** Tuberculomas are usually isointense to hypointense. * **T2 Imaging:** Solid caseation = **T2 Hypointense** (Key differentiator). * **Enhancement:** Both tuberculomas and NCC show **ring enhancement**, but tuberculomas are usually larger (>2cm), often conglomerate, and associated with more significant perilesional edema. * **MR Spectroscopy:** Tuberculomas characteristically show a prominent **Lipid/Lactate peak** at 1.3 ppm due to caseous necrosis.

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: 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?

Ring pattern of enhancement with intravenous contrast and a non-enhancing necrotic center.. **Explanation:** **Glioblastoma Multiforme (GBM)**, a Grade IV Astrocytoma, is the most common and aggressive primary malignant brain tumor in adults. The hallmark imaging feature of GBM on contrast-enhanced MRI is an **irregular, thick, ring-enhancing lesion** surrounding a **central non-enhancing necrotic core**. This occurs because the tumor grows rapidly, outstripping its blood supply and causing central necrosis, while the peripheral viable tumor cells exhibit neoangiogenesis and a breakdown of the blood-brain barrier, leading to contrast uptake. **Analysis of Options:** * **Option C (Correct):** The "ring-enhancement" reflects the peripheral hypervascularity, while the "necrotic center" is a defining pathological feature of GBM (pseudopalisading necrosis). * **Option A & B (Incorrect):** GBM is characteristically **irregular** in shape and **poorly demarcated**. It is highly infiltrative, often spreading along white matter tracts (e.g., crossing the corpus callosum, known as a "Butterfly Glioma"), making it impossible to define clear margins surgically or radiologically. * **Option D (Incorrect):** GBM is almost always associated with significant **vasogenic edema** (appearing hyperintense on T2/FLAIR), which contributes to the mass effect and clinical symptoms like headache and focal deficits. **High-Yield Clinical Pearls for NEET-PG:** * **Butterfly Glioma:** GBM crossing the midline via the corpus callosum. * **Histology:** Look for "pseudopalisading necrosis" and "microvascular proliferation." * **Differential Diagnosis for Ring-Enhancing Lesions (Mnemonic: MAGIC DR):** **M**etastasis, **A**bscess, **G**lioma (GBM), **I**nfarct (subacute), **C**ontusion, **D**emyelination (Tumefactive MS), **R**adiation necrosis.

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.

Question 1

All are X-ray findings of retinoblastoma except?

Accepted Answer

Intracerebral calcification

Answer

Widening of optic canal

Answer

Intraocular calcification

Answer

Secondaries in cranial bones

Question 2

What is the best imaging investigation for parameningeal rhabdomyosarcoma?

Accepted Answer

Magnetic resonance imaging (MRI)

Answer

Cerebrospinal fluid cytology

Answer

Contrast-enhanced computed tomography (CECT)

Answer

Positron emission tomography (PET) scan

Question 3

In cerebral infarct, maximum enhancement on a CT scan is typically seen after how many days?

Accepted Answer

14 days

Answer

2 days

Answer

5 days

Answer

9 days

Question 4

A patient with advanced HIV (CD4 count < 100) presents with headache and blurred vision for 15 days, and neck rigidity on examination. An MRI was performed. What is the most likely diagnosis?

Accepted Answer

Cryptococcosis

Answer

Tuberculosis

Answer

CNS toxoplasmosis

Answer

CNS lymphoma

Question 5

Central T2 hypo intensity is a characteristic imaging feature of which of the following conditions?

Accepted Answer

Tuberculous granuloma with a solid center

Answer

Neurocysticercosis

Answer

Tuberculous granuloma with a liquefied center

Answer

Tubercular abscess

Question 6

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 7

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 8

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 9

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 10

Feeding a nidus is characteristic of which of the following?

Accepted Answer

True arteriovenous malformation

Answer

Venous angioma

Answer

Cavernous angioma

Answer

Hemangioma

Neuroradiology — MCQs

Neuroradiology — MCQs

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