Neuroradiology Practice Questions

Q: What are the characteristic imaging findings in Alzheimer's disease?

Temporal lobe and parietal lobe atrophy. **Explanation:** Alzheimer’s Disease (AD) is the most common cause of dementia, characterized pathologically by amyloid plaques and neurofibrillary tangles. On neuroimaging (MRI), the hallmark finding is **disproportionate atrophy of the medial temporal lobes** (specifically the hippocampus, entorhinal cortex, and amygdala) and the **parietal lobes** (specifically the precuneus and posterior cingulate gyrus). 1. **Why Option A is correct:** The earliest structural changes occur in the hippocampus (temporal lobe), leading to memory deficits. As the disease progresses, atrophy spreads to the temporoparietal association cortex. This pattern results in the characteristic widening of the choroid fissure and temporal horns of the lateral ventricles. 2. **Why other options are wrong:** * **Occipital lobe (B & D):** The primary visual cortex in the occipital lobe is typically spared in AD. Occipital involvement is more characteristic of Posterior Cortical Atrophy (a variant) or Lewy Body Dementia. * **Frontal lobe (C):** While frontal atrophy can occur in late-stage AD, primary frontal and temporal pole atrophy is the hallmark of **Frontotemporal Dementia (FTD)**, not AD. **High-Yield Clinical Pearls for NEET-PG:** * **MTA Score (Scheltens Scale):** Used to grade Medial Temporal lobe Atrophy on coronal T1 MRI. * **FDG-PET Finding:** Characterized by **hypometabolism** in the temporoparietal regions and posterior cingulate gyrus. * **Amyloid PET:** Uses tracers like Pittsburgh Compound B (PiB) to visualize amyloid deposition. * **Key Sign:** "Ex-vacuo" ventriculomegaly due to significant cortical loss.

Q: Which of the following conditions is characterized by bracket calcification?

Corpus callosal lipoma. **Explanation:** **Corpus Callosal Lipoma** is the correct answer. This is a rare congenital lesion resulting from the persistence of the primitive meningeal tissue. On a frontal skull radiograph or a coronal CT scan, it classically presents with **"bracket calcification."** This occurs because the lipoma is often associated with dysgenesis of the corpus callosum, and curvilinear calcifications form along its peripheral margins, resembling parentheses or brackets surrounding the fatty mass. **Analysis of Incorrect Options:** * **Sturge-Weber Syndrome:** Characterized by **"tram-track"** or "railroad track" calcifications. These are cortical and subcortical gyriform calcifications, typically in the occipital or parietal lobes, due to underlying leptomeningeal angiomatosis. * **Cytomegalovirus (CMV) Infection:** Characterized by **periventricular calcifications**. CMV targets the germinal matrix near the ventricles, unlike Toxoplasmosis, which typically causes scattered intracranial calcifications. * **Paragonimus Cyst:** Characterized by **"soap-bubble"** calcifications. This parasitic infection (lung fluke) can migrate to the brain, leading to clustered, ring-like calcified lesions. **High-Yield Pearls for NEET-PG:** * **Lipoma Imaging:** On CT, it shows fat density (negative Hounsfield units, -50 to -100). On MRI, it is hyperintense on T1 and T2, dropping signal on fat-suppression sequences. * **Associated Findings:** Over 50% of callosal lipomas are associated with **corpus callosal agenesis/dysgenesis**. * **Location:** The pericallosal region is the most common site for intracranial lipomas. * **Other Calcification Patterns:** * *Toxoplasmosis:* Scattered/Diffuse. * *Tuberous Sclerosis:* Subependymal nodules ("candle guttering"). * *Oligodendroglioma:* Chunky, intratumoral calcification.

Q: A 10-year-old male patient presents with a 20-day history of headache and vomiting. Examination reveals an ataxic gait. NCCT shows a fourth ventricular mass causing obstructive hydrocephalus. CE-MRI is performed to characterize the lesion. What is the most probable diagnosis?

Ependymoma. ### Explanation The clinical presentation of a posterior fossa mass in a child, specifically located within the **fourth ventricle**, points toward two primary differentials: Ependymoma and Medulloblastoma. **Why Ependymoma is the correct answer:** Ependymomas typically arise from the floor of the fourth ventricle. A key diagnostic feature on imaging is their "plastic" nature—they tend to squeeze through the foramina of Luschka and Magendie into the cerebellopontine angle or the cisterna magna (the **"toothpaste sign"**). On NCCT, they often show **coarse calcifications** (seen in ~50% of cases), which is a significant differentiator from other posterior fossa tumors. **Analysis of Incorrect Options:** * **Medulloblastoma:** While also a fourth ventricular mass, it typically arises from the **roof** (vermis) and is highly cellular, appearing hyperdense on NCCT. It usually expands the ventricle rather than tracking through the foramina. * **Pilocytic Astrocytoma:** This is the most common pediatric cerebellar tumor, but it usually presents as a **cystic lesion with a bright enhancing mural nodule** in the cerebellar hemisphere, not primarily within the fourth ventricle. * **Hemangioblastoma:** These are rare in children (mostly seen in adults or associated with Von Hippel-Lindau syndrome). They appear as highly vascular cystic lesions with an enhancing nodule, similar to astrocytomas but in an older age group. **NEET-PG Clinical Pearls:** * **Location:** Medulloblastoma = Roof of 4th ventricle; Ependymoma = Floor of 4th ventricle. * **Calcification:** Most common in Ependymoma among posterior fossa tumors. * **Imaging Sign:** "Plastic Ependymoma" or "Toothpaste Sign" is pathognomonic for its extension through foramina. * **Hydrocephalus:** Both Medulloblastoma and Ependymoma cause obstructive hydrocephalus due to their midline location.

Q: Which MRI sequence is known as Tractography?

DTI. **Explanation:** **DTI (Diffusion Tensor Imaging)** is the correct answer. It is a specialized MRI technique that measures the **anisotropy** (directionality) of water molecule diffusion. In the brain, water diffuses more easily along the length of white matter axons rather than across them. By mapping these directional vectors, DTI can reconstruct 3D representations of white matter tracts, a process known as **Tractography**. This is clinically vital for preoperative planning to avoid damaging eloquent white matter pathways (e.g., the corticospinal tract). **Analysis of Incorrect Options:** * **DWI (Diffusion Weighted Imaging):** While DTI is an advanced form of DWI, standard DWI only measures the *magnitude* of water diffusion (Brownian motion). It is the gold standard for diagnosing **hyperacute ischemic stroke** (showing restricted diffusion) but does not provide directional tract mapping. * **SWI (Susceptibility Weighted Imaging):** This sequence is highly sensitive to substances that distort the magnetic field, such as **hemosiderin (blood)** and **calcium**. It is used to detect microhemorrhages, diffuse axonal injury (DAI), and venous malformations. * **FLAIR (Fluid Attenuated Inversion Recovery):** This is a T2-weighted sequence where the signal from free fluid (CSF) is suppressed (made black). This makes periventricular pathologies, like **Multiple Sclerosis plaques**, much easier to visualize. **High-Yield Clinical Pearls for NEET-PG:** * **DTI** is the best sequence to differentiate between displacement vs. infiltration of white matter tracts by a tumor. * **Fractional Anisotropy (FA)** is the primary quantitative parameter used in DTI; a decrease in FA usually indicates loss of white matter integrity. * For **Diffuse Axonal Injury (DAI)**, the most sensitive sequences are **SWI** or **GRE** (T2*).

Q: What is the investigation of choice for acute stroke?

CT scan. **Explanation:** In the emergency management of acute stroke, the primary goal is to differentiate between **ischemic** and **hemorrhagic** stroke to determine if thrombolytic therapy (like tPA) can be safely administered. **1. Why CT Scan is the Correct Answer:** A **Non-Contrast Computed Tomography (NCCT) scan of the head** is the initial investigation of choice because of its high sensitivity in detecting **acute intracranial hemorrhage** (which appears hyperdense/white). It is fast, widely available, and cost-effective. In the hyperacute phase of an ischemic stroke (first 6 hours), the CT may appear normal, but its main utility is to "rule out" a bleed before starting anticoagulants or fibrinolytics. **2. Why the other options are incorrect:** * **MRI Angiography:** While excellent for visualizing vascular occlusions or aneurysms, it is time-consuming and not the first-line screening tool in an emergency setting. * **Functional MRI:** This is primarily used in research or pre-surgical mapping to study brain activity/metabolism; it has no role in the emergency diagnosis of acute stroke. * **Contrast CT:** Contrast is generally avoided in the initial screening because extravasated contrast can mimic the appearance of blood (hyperdensity), potentially leading to a misdiagnosis of hemorrhage. **Clinical Pearls for NEET-PG:** * **Earliest sign of Ischemic Stroke on CT:** "Hyperdense Middle Cerebral Artery (MCA) sign." * **Other early CT signs:** Insular ribbon sign, blurring of the gray-white matter interface, and sulcal effacement. * **Gold Standard for Ischemia:** **Diffusion-Weighted Imaging (DWI) MRI** is the most sensitive sequence for detecting early infarcts (within minutes), but NCCT remains the "investigation of choice" for initial triage. * **Door-to-CT time goal:** Should ideally be within 20–25 minutes of hospital arrival.

Q: A 25-year-old male presents to the emergency department following an accident with symptoms of headache and paralysis. A CT scan reveals subarachnoid hemorrhage. What is the next investigation of choice?

4-Vessel angiography. ### Explanation **Correct Option: C. 4-Vessel Angiography** In the context of a Subarachnoid Hemorrhage (SAH), the primary goal after confirming the bleed on a non-contrast CT (NCCT) is to identify the underlying vascular etiology (most commonly a ruptured berry aneurysm). **4-Vessel Angiography (Digital Subtraction Angiography - DSA)** remains the **gold standard** investigation. It allows for a high-resolution, 360-degree evaluation of the cerebral vasculature (both carotids and both vertebral arteries) and provides the necessary anatomical detail for surgical clipping or endovascular coiling. **Why other options are incorrect:** * **A. MRI:** While sensitive for chronic blood or associated parenchymal lesions, MRI is not the primary investigation for acute vascular mapping in SAH due to its time-consuming nature and lower sensitivity for small aneurysms compared to DSA. * **B. SPECT:** This is a functional imaging modality used to assess regional cerebral blood flow. It has no role in the acute diagnosis or anatomical localization of the cause of SAH. * **D. Doppler USG:** Transcranial Doppler is used bedside to monitor for **vasospasm** (a common complication occurring 3–14 days post-SAH) but cannot reliably identify the source of the hemorrhage. **Clinical Pearls for NEET-PG:** * **Initial Investigation of Choice (IOC):** Non-Contrast CT (NCCT) Head (shows hyperdensity in basal cisterns/Sylvian fissure). * **Gold Standard Investigation:** 4-Vessel Angiography (DSA). * **Most Common Cause (Spontaneous):** Ruptured Berry Aneurysm (most common site: Anterior Communicating Artery). * **Most Common Cause (Overall):** Trauma. * **Xanthochromia:** If CT is negative but clinical suspicion is high, a Lumbar Puncture showing yellowish CSF (bilirubin) confirms SAH.

Q: A 12-year-old boy presents with a 6-month history of progressive intellectual decline, behavioral changes, and myoclonic jerks. CT brain shows diffuse cortical atrophy with periventricular white matter hypodensity. Which of the following viral infections is the most likely underlying cause?

Measles. ***Measles*** - The clinical triad of **progressive intellectual decline**, **myoclonic jerks**, and **behavioral changes** in a 12-year-old is pathognomonic for **Subacute Sclerosing Panencephalitis (SSPE)**, a rare complication of measles virus. - CT findings of **diffuse cortical atrophy** with **periventricular white matter hypodensity** are characteristic imaging features of SSPE, reflecting chronic viral-induced neurodegeneration. *Varicella* - Varicella-associated encephalitis typically presents with **acute cerebellar symptoms** like ataxia and coordination problems, not progressive intellectual decline. - CT brain changes in varicella encephalitis predominantly show **cerebellar edema** and hemorrhage, not the cortical atrophy pattern seen here. *Mumps* - Mumps encephalitis presents as **acute viral encephalitis** with fever, headache, and altered consciousness, not chronic progressive deterioration. - CT findings are typically **non-specific acute changes** like cerebral edema, lacking the characteristic periventricular white matter hypodensity of SSPE. *Rubella* - **Congenital rubella syndrome** may cause neurological complications, but presents with **periventricular calcifications** on CT, not white matter hypodensity. - Acquired rubella infection rarely causes chronic progressive neurological deterioration; it typically presents as **acute encephalitis** with different imaging patterns.

Q: A male child presents with hyperintensities on T2-weighted MRI in the bilateral frontal lobes. What is the most probable diagnosis?

Alexander disease. ### **Explanation** The correct answer is **Alexander disease**. This diagnosis is primarily based on the characteristic neuroimaging pattern of **frontal lobe predominance** of white matter involvement. #### **1. Why Alexander Disease is Correct** Alexander disease is a rare leukodystrophy caused by mutations in the **GFAP gene**, leading to the accumulation of Rosenthal fibers in astrocytes. On MRI, it presents with symmetrical T2-weighted hyperintensities that classically begin in the **frontal lobes** and progress posteriorly. Other key imaging features include involvement of the caudate nuclei, thalamus, and contrast enhancement of affected white matter. #### **2. Analysis of Incorrect Options** * **Canavan Disease:** Characterized by **diffuse** white matter involvement with a hallmark involvement of the **subcortical U-fibers**. A key diagnostic feature is elevated **N-acetylaspartate (NAA)** on MR spectroscopy. * **Krabbe Disease:** Typically involves the **posterior** white matter (parieto-occipital) and is associated with hyperdensity of the thalami on CT and enlargement of the optic nerves. * **X-linked Adrenoleukodystrophy (X-ALD):** Classically shows a **posterior-to-anterior** progression, primarily affecting the **occipital and parietal lobes** and the splenium of the corpus callosum. #### **3. NEET-PG Clinical Pearls: Leukodystrophy Patterns** To quickly differentiate leukodystrophies on MRI, remember these "High-Yield Patterns": * **Frontal Predominance:** Alexander Disease. * **Posterior (Occipital) Predominance:** X-linked Adrenoleukodystrophy. * **Diffuse + Subcortical U-fibers + High NAA:** Canavan Disease. * **Diffuse + Subcortical U-fibers + Macrocephaly:** Alexander and Canavan (both have large heads). * **"Tigroid" Pattern:** Metachromatic Leukodystrophy (sparing of perivascular white matter).

Q: A 5-year-old child presents with a cystic lesion with an enhancing mural nodule in the cerebellar hemisphere on brain MRI. What is the most likely diagnosis?

Pilocytic astrocytoma. **Explanation:** The clinical presentation of a **cystic lesion with an enhancing mural nodule** in the cerebellum of a child is the classic imaging hallmark of **Pilocytic Astrocytoma (Grade I)**. It is the most common primary brain tumor in children. **Why Pilocytic Astrocytoma is correct:** * **Demographics:** Typically occurs in the first two decades of life. * **Location:** Most commonly found in the posterior fossa (cerebellum). * **Imaging:** Characterized by a large fluid-filled cyst and a solid, intensely enhancing mural nodule. On MRI, the cyst wall usually does not enhance unless it contains tumor cells. **Why other options are incorrect:** * **Meningioma:** These are extra-axial, dural-based tumors that are rare in children and typically present as solid, intensely enhancing masses with a "dural tail" sign. * **Schwannoma:** Most commonly involves the CN VIII (Vestibulocochlear nerve) at the cerebellopontine angle. While they can be cystic, they are rare in 5-year-olds unless associated with Neurofibromatosis Type 2. * **Glioma:** While Pilocytic Astrocytoma is a type of low-grade glioma, "Glioma" is a broad category. In NEET-PG, when a specific classic presentation is given, the most specific histological diagnosis is preferred. **High-Yield Clinical Pearls for NEET-PG:** * **Histology:** Look for **Rosenthal fibers** (corkscrew-shaped eosinophilic bundles) and bipolar cells with long hair-like processes (pilocytes). * **Genetics:** Strongly associated with **BRAF gene** alterations and **Neurofibromatosis Type 1 (NF1)**, especially when involving the optic pathway (Optic Glioma). * **Differential Diagnosis:** Hemangioblastoma also presents as a "cyst with a nodule" but is more common in adults and associated with Von Hippel-Lindau (VHL) syndrome.

Question 1

What are the characteristic imaging findings in Alzheimer's disease?

Accepted Answer

Temporal lobe and parietal lobe atrophy

Answer

Temporal and occipital lobe atrophy

Answer

Frontal and parietal lobe atrophy

Answer

Parietal and occipital lobe atrophy

Question 2

Which of the following conditions is characterized by bracket calcification?

Accepted Answer

Corpus callosal lipoma

Answer

Sturge Weber syndrome

Answer

Cytomegalovirus (CMV) infection

Answer

Paragonimus cyst

Question 3

A 10-year-old male patient presents with a 20-day history of headache and vomiting. Examination reveals an ataxic gait. NCCT shows a fourth ventricular mass causing obstructive hydrocephalus. CE-MRI is performed to characterize the lesion. What is the most probable diagnosis?

Accepted Answer

Ependymoma

Answer

Medulloblastoma

Answer

Pilocytic astrocytoma

Answer

Hemangioblastoma

Question 4

Which MRI sequence is known as Tractography?

Accepted Answer

DTI

Answer

DWI

Answer

SWI

Answer

FLAIR

Question 5

Which vessels are typically catheterized during carotid angiography?

Accepted Answer

Two internal carotids and one vertebral

Answer

Two external carotids and two vertebrals

Answer

Two internal carotids and two vertebrals

Answer

Two external carotids and one vertebral

Question 6

What is the investigation of choice for acute stroke?

Accepted Answer

CT scan

Answer

MRI angiography

Answer

Functional MRI

Answer

Contrast CT

Question 7

A 25-year-old male presents to the emergency department following an accident with symptoms of headache and paralysis. A CT scan reveals subarachnoid hemorrhage. What is the next investigation of choice?

Accepted Answer

4-Vessel angiography

Answer

MRI

Answer

SPECT

Answer

Doppler USG

Question 8

A 12-year-old boy presents with a 6-month history of progressive intellectual decline, behavioral changes, and myoclonic jerks. CT brain shows diffuse cortical atrophy with periventricular white matter hypodensity. Which of the following viral infections is the most likely underlying cause?

Accepted Answer

Measles

Answer

Varicella

Answer

Mumps

Answer

Rubella

Question 9

A male child presents with hyperintensities on T2-weighted MRI in the bilateral frontal lobes. What is the most probable diagnosis?

Accepted Answer

Alexander disease

Answer

Canavan disease

Answer

Krabbe disease

Answer

X-linked adrenoleukodystrophy

Question 10

A 5-year-old child presents with a cystic lesion with an enhancing mural nodule in the cerebellar hemisphere on brain MRI. What is the most likely diagnosis?

Accepted Answer

Pilocytic astrocytoma

Answer

Meningioma

Answer

Schwannoma

Answer

Glioma

Neuroradiology — MCQs

Neuroradiology — MCQs

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