Neuroradiology Practice Questions

Q: What is the investigation of choice in the clinical suspicion of stroke?

Noncontrast head CT. **Explanation:** In the acute management of a suspected stroke, the primary clinical objective is to differentiate between **ischemic stroke** and **hemorrhagic stroke**. This distinction is critical because the treatment for ischemia (thrombolysis) is contraindicated and potentially fatal in the presence of a hemorrhage. **Why Noncontrast Head CT (NCCT) is the Correct Choice:** NCCT is the gold standard initial investigation because it is highly sensitive for detecting **acute intracranial hemorrhage**, which appears immediately as a hyperdense (white) area. It is fast, widely available, and cost-effective. While NCCT may appear normal in the early stages of an ischemic stroke (the "hyperacute" phase), its main role is to **rule out bleed** so that fibrinolytic therapy (like tPA) can be safely initiated. **Why Other Options are Incorrect:** * **Contrast Head CT:** Intravenous contrast can mimic the appearance of blood (hyperdensity) on a CT scan, potentially masking a small hemorrhage or leading to a false diagnosis of a bleed. * **MRI (Noncontrast/Contrast):** While Diffusion-Weighted Imaging (DWI) MRI is the most sensitive sequence for detecting early *ischemic* changes (within minutes), MRI is time-consuming, less available in emergency settings, and has more contraindications (e.g., pacemakers). It is generally reserved for stable patients or cases where the diagnosis is uncertain. **High-Yield Clinical Pearls for NEET-PG:** * **"Time is Brain":** The goal is a "Door-to-CT" time of <25 minutes. * **Earliest CT sign of Ischemic Stroke:** The **"Hyperdense Middle Cerebral Artery (MCA) sign"** (representing a thrombus). * **Diffusion-Weighted Imaging (DWI):** The most sensitive imaging modality for hyperacute ischemic stroke (detects changes within 15–30 minutes). * **Ischemic Penumbra:** The salvageable brain tissue around the infarct core, best identified using CT or MR Perfusion imaging.

Q: Extensive involvement of deep white matter with hyperdense thalamic lesion on non-contrast CT scan of the brain is seen in which of the following conditions?

Krabbe disease. ### Explanation The correct answer is **Krabbe disease** (Globoid Cell Leukodystrophy). **1. Why Krabbe Disease is Correct:** Krabbe disease is an autosomal recessive lysosomal storage disorder caused by a deficiency of the enzyme **galactocerebrosidase**. This leads to the accumulation of psychosine, which is toxic to oligodendrocytes. * **Radiological Hallmark:** On a non-contrast CT (NCCT), Krabbe disease characteristically shows **hyperdensity in the thalami**, caudate nuclei, and posterior limb of the internal capsule. This is attributed to the presence of dense "globoid cells" and calcification. * **White Matter Involvement:** It involves extensive symmetric demyelination of the deep white matter, often starting posteriorly (parieto-occipital) and spreading anteriorly. **2. Why Other Options are Incorrect:** * **Alexander Disease:** Characterized by **frontal lobe** predominance of white matter changes. A key finding is "Rosenthal fibers" on pathology and macrocephaly clinically. * **Metachromatic Leukodystrophy (MLD):** The most common leukodystrophy. It shows a characteristic **"tigroid" or "leopard skin" pattern** (sparing of perivenular myelin) on MRI. It typically does *not* show hyperdense thalami on CT. * **Canavan Disease:** Characterized by diffuse white matter involvement with a hallmark of **elevated N-acetylaspartate (NAA) peak** on MR spectroscopy and macrocephaly. **3. High-Yield Clinical Pearls for NEET-PG:** * **Hyperdense Thalami on CT:** Think Krabbe disease or GM1 Gangliosidosis. * **Macrocephaly + Leukodystrophy:** Think Alexander disease or Canavan disease. * **Tigroid Pattern:** Pathognomonic for MLD. * **Parieto-occipital Predominance:** Seen in Krabbe and X-linked Adrenoleukodystrophy (ALD).

Q: A 12-year-old boy presents with seizures. His mother reports multiple previous hospitalizations for difficult-to-control seizures. A CT scan was performed. What is the diagnosis?

Tuberous sclerosis. ***Tuberous sclerosis*** - Characterized by **subependymal calcified nodules** and **cortical tubers** on CT, which are pathognomonic findings in children with refractory seizures. - Classic presentation includes **difficult-to-control seizures** in childhood, often associated with **developmental delay** and **autism spectrum disorders**. *Sturge Weber Syndrome* - CT typically shows **pial angiomatosis** with **gyriform calcifications** in the occipital and parietal regions, not subependymal nodules. - Associated with **port-wine stain** facial birthmark and **glaucoma**, which are not mentioned in this case. *Neurofibromatosis* - CT findings include **neurofibromas** and **optic gliomas**, not the calcified nodules seen in tuberous sclerosis. - Typically presents with **café-au-lait spots** and **neurofibromas** rather than primarily seizure disorders. *Von Hippel Lindau Syndrome* - CT shows **cerebellar hemangioblastomas** and **retinal angiomas**, not cortical tubers or subependymal nodules. - Primarily affects **young adults** rather than children and rarely presents with seizures as the main symptom.

Q: The MRI finding shown in the image is characteristic of which of the following pathologies?

Multiple Sclerosis. ***Multiple Sclerosis*** - **Periventricular white matter lesions** (Dawson's fingers) on **FLAIR MRI** are pathognomonic for multiple sclerosis, showing demyelinating plaques perpendicular to ventricles. - The **finger-like projections** extending from ventricles represent perivenular inflammation and demyelination characteristic of MS pathophysiology. *Sturge-Weber syndrome* - Typically shows **tram-track calcifications** in the cortex on CT imaging, not periventricular white matter lesions. - Associated with **leptomeningeal angiomatosis** and cortical atrophy, distinctly different from the shown MRI pattern. *Neurofibromatosis* - MRI findings include **schwannomas**, **optic gliomas**, and **café-au-lait spots**, not periventricular white matter lesions. - **Neurofibromas** along nerve pathways and **sphenoid wing dysplasia** are characteristic imaging features, absent in this case. *Tuberous Sclerosis* - Characteristic findings include **cortical tubers**, **subependymal nodules**, and **candle-guttering calcifications** on imaging. - **Subependymal giant cell astrocytomas** near the foramen of Monro are typical, not the periventricular pattern shown.

Q: Which one of the following tumors shows calcification on CT Scan?

Meningioma. **Explanation:** **Meningioma (Correct Answer):** Meningiomas are the most common extra-axial tumors in adults. Calcification is a hallmark feature, seen in approximately **20–25% of cases** on CT scans. This is often due to the presence of **psammoma bodies** (laminated calcifications). On a non-contrast CT (NCCT), meningiomas typically appear as well-circumscribed, hyperdense dural-based masses that show intense homogenous enhancement after contrast administration. **Analysis of Incorrect Options:** * **CNS Lymphoma:** Typically appears as a hyperdense mass on NCCT due to high cellularity and a high nuclear-to-cytoplasmic ratio, but **calcification is extremely rare** in untreated cases. * **Medulloblastoma:** While these are hyperdense on CT due to dense cell packing, calcification occurs in less than 10% of cases. They are primarily midline posterior fossa tumors in children. * **Ependymoma:** While ependymomas (especially the infratentorial type) *can* show calcification (about 50% of cases), **Meningioma** is the classic and more frequently tested association for intracranial calcification in the context of adult tumors in NEET-PG. *Note: If the question specifically targeted pediatric posterior fossa tumors, Ependymoma would be a stronger candidate for calcification than Medulloblastoma.* **High-Yield Pearls for NEET-PG:** * **Most common intracranial tumor to calcify:** Craniopharyngioma (up to 90% in children). * **Most common glial tumor to calcify:** Oligodendroglioma ("90% calcify"). * **Dural Tail Sign:** Highly suggestive of Meningioma (though not pathognomonic). * **Hyperostosis:** Thickening of the adjacent bone is a classic CT finding in Meningioma.

Q: Presence of calcification on an intracranial lesion is best made out by?

CT scan. **Explanation:** The detection of intracranial calcification is a high-yield topic in neuroradiology. The correct answer is **CT Scan** because it is the gold standard for identifying calcium due to its high sensitivity to electron density. **1. Why CT Scan is the Correct Answer:** Calcium has a high atomic number, which causes significant attenuation of X-ray beams. On a CT scan, this appears as **hyperdensity** (bright white), typically measuring >100 Hounsfield Units (HU). CT can detect even minute, punctate calcifications that other modalities might miss, making it essential for diagnosing conditions like oligodendrogliomas, craniopharyngiomas, or neurocysticercosis (granulomatous stage). **2. Why Other Options are Incorrect:** * **MRI:** While certain sequences (like Susceptibility Weighted Imaging - SWI) can detect mineral deposits, calcium often has a variable appearance on standard T1/T2 sequences (usually dark/hypointense). It is difficult to distinguish calcium from hemorrhage or flow voids on MRI. * **USG:** Ultrasound is limited in adults due to the thick cranial vault (bone) which reflects sound waves. It is only useful in neonates through the open fontanelle. * **Contrast Study:** Contrast (Iodine or Gadolinium) is used to check for blood-brain barrier breakdown or vascularity. It can actually mask calcification by making the surrounding lesion bright, making it harder to differentiate pre-existing calcium. **Clinical Pearls for NEET-PG:** * **Most common physiological intracranial calcification:** Pineal gland (seen in >50% of adults). * **"Popcorn" calcification:** Classic for Cavernous Hemangioma. * **"Tram-track" calcification:** Pathognomonic for Sturge-Weber Syndrome. * **Best MRI sequence for calcium/blood:** SWI (Susceptibility Weighted Imaging) or Gradient Echo (GRE).

Question 1

Which of the following is a characteristic radiological finding of an epidermoid cyst?

Accepted Answer

High signal on diffusion-weighted MRI

Answer

Low signal on diffusion-weighted MRI

Answer

High signal on FLAIR MRI

Answer

High signal on STIR MRI

Question 2

What is the investigation of choice in the clinical suspicion of stroke?

Accepted Answer

Noncontrast head CT

Answer

Contrast head CT

Answer

Noncontrast head MRI

Answer

Contrast head MRI

Question 3

A 50-year-old female presented with left-sided lower limb weakness and mild headaches. Her weakness worsened slowly over the past 5 years. She has a history of cranial irradiation 6 years ago. Her husband has also noted a slight change in her behavior over the past 5 years. Contrast-enhanced MRI showed a sellar/suprasellar space-occupying lesion (SOL). Which of the following is the most common gyri involved and the most common genetic abnormality in the condition suggested by the MRI findings?

Accepted Answer

Anterior paracentral / Deletion 22q

Answer

Posterior paracentral / Deletion 20q

Answer

Anterior paracentral / Deletion 20q

Answer

Posterior paracentral / Deletion 22q

Question 4

Extensive involvement of deep white matter with hyperdense thalamic lesion on non-contrast CT scan of the brain is seen in which of the following conditions?

Accepted Answer

Krabbe disease

Answer

Alexander disease

Answer

Metachromatic leukodystrophy

Answer

Canavan disease

Question 5

A 12-year-old boy presents with seizures. His mother reports multiple previous hospitalizations for difficult-to-control seizures. A CT scan was performed. What is the diagnosis?

Accepted Answer

Tuberous sclerosis

Answer

Sturge Weber Syndrome

Answer

Neurofibromatosis

Answer

Von Hippel Lindau Syndrome

Question 6

The MRI finding shown in the image is characteristic of which of the following pathologies?

Accepted Answer

Multiple Sclerosis

Answer

Sturge-Weber syndrome

Answer

Neurofibromatosis

Answer

Tuberous Sclerosis

Question 7

Which of the following is true regarding cerebral venous sinuses?

Accepted Answer

Transverse sinus is unequal

Answer

Cerebral venous thrombosis causes enophthalmos

Answer

Cerebral venous thrombosis causes empty delta sign

Answer

Cerebral venous sinuses communicate with the subdural space

Question 8

Which of the following imaging sequences is most useful in differentiating between an arachnoid cyst and an epidermoid cyst?

Accepted Answer

FLAIR

Answer

T1 weighted MRI

Answer

Smooth margin

Answer

Contrast enhancement

Question 9

Which one of the following tumors shows calcification on CT Scan?

Accepted Answer

Meningioma

Answer

Ependymoma

Answer

CNS lymphoma

Answer

Medulloblastoma

Question 10

Presence of calcification on an intracranial lesion is best made out by?

Accepted Answer

CT scan

Answer

MRI

Answer

USG

Answer

Contrast study

Neuroradiology — MCQs

Neuroradiology — MCQs

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