Neuroradiology Practice Questions

Q: What is the characteristic MRI brain appearance described as a 'soap bubble'?

Cryptococcosis. **Explanation:** **Cryptococcosis** is the correct answer. The characteristic **'soap bubble' appearance** on MRI refers to **gelatinous pseudocysts**. These occur when the fungus *Cryptococcus neoformans* spreads from the subarachnoid space into the perivascular spaces (Virchow-Robin spaces) of the basal ganglia and thalamus. The fungus secretes a copious amount of capsular polysaccharide, which expands these spaces with mucoid material. On MRI, these appear as multiple small, non-enhancing, fluid-filled lesions that mimic soap bubbles. **Analysis of Incorrect Options:** * **Neurocysticercosis (A):** Characterized by the "hole-with-a-dot" appearance (scolex within a cyst). It progresses through four stages (vesicular, colloidal, granular, and calcified), but does not form gelatinous pseudocysts. * **Tuberculosis (C):** Typically presents as basal meningitis or tuberculomas. Tuberculomas show "ring enhancement" and often have a central area of caseous necrosis, appearing as a "target sign." * **Toxoplasmosis (D):** The classic finding is multiple ring-enhancing lesions with significant perilesional edema, often showing the "eccentric target sign" (a small nodule of enhancement along the wall of the ring). **NEET-PG High-Yield Pearls:** * **Organism:** *Cryptococcus neoformans* (most common fungal CNS infection in HIV/AIDS). * **Imaging:** Soap bubble appearance = Basal ganglia gelatinous pseudocysts. * **Diagnosis:** India Ink preparation (shows halo) or Cryptococcal Antigen (CrAg) test. * **Treatment:** Induction with Amphotericin B + Flucytosine, followed by Fluconazole.

Q: Which of the following tend to show marked and homogeneous enhancement on Gd-DTPA enhanced MRI?

Meningiomas and acoustic neuromas. **Explanation:** The degree and pattern of contrast enhancement on MRI depend on the integrity of the **blood-brain barrier (BBB)** and the vascularity of the lesion. **1. Why Option A is Correct:** Both **Meningiomas** and **Acoustic Neuromas (Vestibular Schwannomas)** are **extra-axial tumors**. Unlike intra-axial brain tissue, extra-axial tumors do not possess a blood-brain barrier. Consequently, Gadolinium-DTPA easily leaks into the interstitial space, resulting in **intense, marked, and homogeneous enhancement**. This is a classic radiological hallmark for these tumors. **2. Analysis of Incorrect Options:** * **Option B:** **Oligodendrogliomas** often show little to no enhancement (or patchy enhancement), and **Metastases** frequently show "ring enhancement" due to central necrosis rather than homogeneous enhancement. * **Option C:** **Low-grade gliomas** (WHO Grade II) typically show **no enhancement** because the BBB remains relatively intact. * **Option D:** **Glioblastoma Multiforme (GBM)** is characterized by rapid growth and central necrosis, leading to a classic **irregular, thick ring-enhancement** pattern rather than a homogeneous one. **3. High-Yield Clinical Pearls for NEET-PG:** * **Meningioma:** Look for the **"Dural Tail Sign"** on contrast MRI (thickening of the adjacent dura). * **Acoustic Neuroma:** Look for the **"Ice-cream cone appearance"** (expansion of the internal auditory canal). * **Ring Enhancing Lesions (Mnemonic: MAGIC DR):** Metastasis, Abscess, Glioma (GBM), Infarct, Contusion, Demyelination (Tumescent MS), Radiation necrosis. * **Non-enhancing tumor:** Low-grade astrocytoma is the most common example.

Q: A patient was diagnosed with intracranial cavernous angioma on MR scan. What MRI finding is characteristic of this lesion?

Popcorn-like lesion. **Explanation:** **Intracranial Cavernous Angiomas** (also known as cavernomas or cavernous malformations) are low-flow vascular malformations consisting of a "mulberry-like" cluster of dilated, thin-walled capillaries without intervening brain parenchyma. 1. **Why Option D is Correct:** On MRI, the characteristic appearance is a **"Popcorn-like" lesion**. This is due to multiple locules containing blood products at various stages of degradation (methemoglobin, ferritin). On **T2-weighted imaging**, this central reticulated core is typically surrounded by a **hypointense rim of hemosiderin** (the "hemosiderin halo"), which is best visualized on Gradient Echo (GRE) or Susceptibility Weighted Imaging (SWI) due to the "blooming effect." 2. **Why Other Options are Incorrect:** * **Options A & B (Nidus and Arterial Feeders):** These are classic features of **Arteriovenous Malformations (AVMs)**. Cavernomas are "angiographically occult" because they lack high-flow arterial supply or a shunting nidus. * **Option C (Phlebectasis):** This refers to dilated veins, which is more characteristic of **Developmental Venous Anomalies (DVAs)**. While DVAs are often associated with cavernomas (mixed malformations), phlebectasis itself is not the diagnostic feature of the cavernoma. **High-Yield Clinical Pearls for NEET-PG:** * **Gold Standard Investigation:** MRI (specifically GRE/SWI sequences). * **Angiography:** Usually normal (Occult). * **Clinical Presentation:** Most commonly presents with **seizures** or focal neurological deficits due to micro-hemorrhages. * **Zabramski Classification:** Used to grade cavernous malformations based on MRI appearance. * **Classic Description:** "Popcorn appearance" with a "hemosiderin rim."

Q: What is the stage of neurocysticercosis characterized by a visible cyst with a scolex and minimal edema?

Vesicular. Neurocysticercosis (NCC), caused by the larvae of *Taenia solium*, progresses through four distinct radiologic stages. Understanding these is high-yield for NEET-PG. **Correct Answer: A. Vesicular Stage** In the **Vesicular stage**, the parasite is alive and viable. The host’s immune system has not yet recognized the larva, resulting in **minimal to no surrounding edema** or inflammation. Radiologically, it appears as a well-defined CSF-density cyst. The pathognomonic feature is the **"hole-with-a-dot" appearance**, where the "dot" represents the eccentric, opaque **scolex** (the head of the tapeworm). **Why the other options are incorrect:** * **B. Colloidal Vesicular:** The larva begins to die, and the cyst fluid becomes turbid. This triggers a robust immune response, leading to significant **perilesional edema** and intense **ring enhancement** on MRI/CT. * **C. Granular Nodular:** The cyst retracts and thickens. Edema decreases as the lesion transforms into an enhancing nodule. * **D. Calcific Nodular:** The final "healed" stage. The lesion becomes a small, shrunken, hyperdense **calcified speck** (best seen on CT). There is no edema and the scolex is no longer distinguishable. **High-Yield Clinical Pearls for NEET-PG:** * **Most common presentation:** New-onset seizures in an adult (in endemic areas). * **Imaging of Choice:** **MRI** is superior for identifying the scolex and staging; **CT** is superior for the calcific stage. * **Treatment Paradox:** Initiating cysticidal drugs (Albendazole/Praziquantel) during the vesicular or colloidal stage can worsen edema due to parasite death; hence, **corticosteroids** are often co-administered.

Q: A 40-year-old female patient presented with recurrent headaches. MRI showed an extra-axial, dural-based, and enhancing lesion. What is the most likely diagnosis?

Meningioma. ### Explanation **Correct Answer: A. Meningioma** **Why it is correct:** The description provided—**extra-axial, dural-based, and enhancing**—is the classic radiologic triad for a **Meningioma**. * **Extra-axial:** This means the lesion arises outside the brain parenchyma. Key signs include the displacement of gray matter and the presence of a "CSF cleft" between the mass and the brain. * **Dural-based:** Meningiomas arise from arachnoid cap cells. On MRI, they typically show a **"Dural Tail Sign"** (thickening and enhancement of the adjacent dura mater). * **Enhancing:** They are highly vascular and show intense, homogenous contrast enhancement. They are more common in females (middle-aged) due to progesterone receptors. **Why the other options are incorrect:** * **B. Glioma:** These are **intra-axial** tumors (arising from within the brain tissue). They typically lack a dural attachment and often show irregular enhancement or necrosis (especially Glioblastoma). * **C. Schwannoma:** While extra-axial, these typically arise from cranial nerves (most commonly CN VIII in the cerebellopontine angle). They do not usually present as broad-based dural lesions across the vault. * **D. Pituitary Adenoma:** These are specific to the **sella turcica**. While they are extra-axial and enhance, the location is restricted to the sellar/suprasellar region, not general dural surfaces. **High-Yield Clinical Pearls for NEET-PG:** * **Most common** primary intracranial tumor in adults. * **MRI Hallmark:** "Dural Tail Sign" and "CSF Cleft Sign." * **Histology:** Look for **Psammoma bodies** (concentric calcifications) and whorled patterns. * **Association:** Multiple meningiomas are strongly associated with **Neurofibromatosis Type 2 (NF2)**. * **Hyperostosis:** They often cause thickening of the overlying bone, which can be seen on CT.

Q: Which of the following lesions characteristically shows a biconvex shape on CT scan?

Epidural hematoma. ### Explanation **1. Why Epidural Hematoma (EDH) is the Correct Answer:** An **Epidural Hematoma** occurs due to bleeding into the potential space between the skull and the dura mater, most commonly following a rupture of the **middle meningeal artery** (associated with temporal bone fractures). The characteristic **biconvex (lentiform or lemon-shaped)** appearance on a CT scan occurs because the dura mater is firmly attached to the skull at the **cranial sutures**. As the arterial blood collects, it exerts high pressure, stripping the dura away from the bone but remaining confined by these sutural attachments. This forces the hematoma to expand inward toward the brain, creating the classic convex shape. **2. Why Other Options are Incorrect:** * **Subdural Hematoma (SDH):** These occur due to the tearing of **bridging veins** between the dura and the arachnoid mater. Since this space is not limited by sutures, the blood spreads thinly and widely along the brain's surface, resulting in a **crescent-shaped (concave)** appearance. Unlike EDH, SDH can cross suture lines but is limited by dural reflections like the falx cerebri. **3. Clinical Pearls for NEET-PG:** * **Lucid Interval:** Classically associated with EDH (the patient regains consciousness briefly before deteriorating). * **Suture Lines:** EDH **does not** cross suture lines (limited by dural attachments), whereas SDH **does** cross suture lines. * **Source of Bleed:** EDH is usually **arterial** (Middle Meningeal Artery); SDH is usually **venous** (Bridging Veins). * **Hyperdensity:** On NCCT, acute blood appears hyperdense (bright white). As it ages (chronic SDH), it becomes isodense or hypodense.

Q: Bilateral symmetrical basal ganglia calcification is seen with which condition?

Fahr's disease. **Explanation:** **Fahr’s Disease (Idiopathic Basal Ganglia Calcification)** is the correct answer. It is a rare genetic neurological disorder characterized by abnormal, **bilateral, and symmetrical calcium deposits** in the basal ganglia, thalamus, and cerebral cortex. While secondary causes of such calcification include metabolic disorders (most commonly **hypoparathyroidism**), Fahr’s disease refers to the primary, idiopathic, or familial form. On CT, these appear as hyperdense areas typically involving the globus pallidus, putamen, and caudate nuclei. **Analysis of Incorrect Options:** * **Wilson’s Disease:** Characterized by copper deposition rather than calcium. On MRI, it typically shows the **"Face of the Giant Panda"** sign (hyperintensity in the tegmentum with preserved red nuclei) and T2 hyperintensities in the basal ganglia, not symmetrical calcification. * **Cytomegalovirus (CMV):** A common cause of congenital infection. It typically presents with **periventricular calcifications** and microcephaly, rather than isolated basal ganglia involvement. * **Toxoplasmosis:** Congenital toxoplasmosis presents with **diffuse, scattered parenchymal calcifications** and obstructive hydrocephalus. In HIV patients, it presents as ring-enhancing lesions. **NEET-PG High-Yield Pearls:** * **CT is the gold standard** for detecting intracranial calcification (appears hyperdense/white). * The most common cause of pathological basal ganglia calcification is **Hypoparathyroidism** (always check serum calcium/PTH). * **"Face of the Miniature Panda"** sign is seen in the midbrain tegmentum in Wilson’s Disease. * **Differential for Basal Ganglia lesions:** Carbon monoxide poisoning (necrosis), Wilson's (copper), and Fahr's (calcium).

Q: On MR-spectroscopy, what peak is typically seen at 3.2 ppm?

Choline. **Explanation:** Magnetic Resonance Spectroscopy (MRS) is a non-invasive imaging technique used to measure the concentration of specific metabolites in the brain. The position of these metabolites on the frequency axis is measured in **parts per million (ppm)**. **1. Why Choline is correct:** **Choline (Cho)** resonates at **3.2 ppm**. It is a marker of cell membrane turnover (synthesis and degradation). In clinical practice, an elevated Choline peak is a hallmark of increased cellular proliferation, making it a sensitive indicator for **malignant tumors** (e.g., high-grade gliomas) and inflammatory processes. **2. Analysis of Incorrect Options:** * **Lipid and Lactate (0.9–1.3 ppm):** These peaks are found at the far right of the spectrum. Lactate (1.3 ppm) indicates anaerobic glycolysis and is seen in necrotic tumors or cerebral ischemia. * **N-acetyl aspartate (NAA) (2.0 ppm):** NAA is a marker of neuronal integrity. A decrease in NAA signifies neuronal loss or damage, commonly seen in tumors, infarcts, or neurodegenerative diseases. * **Creatine (Cr) (3.0 ppm):** Creatine represents energy metabolism. It is the most stable peak and is often used as a reference point to calculate metabolite ratios (e.g., Cho/Cr ratio). **High-Yield Clinical Pearls for NEET-PG:** * **Hunter’s Angle:** On a normal MRS, the peaks of NAA, Cr, and Cho form an ascending line (45-degree angle). In brain tumors, this angle is reversed (Cho rises, NAA falls), known as the **"Steal Phenomenon"** or "Inverted Hunter's Angle." * **Alanine (1.48 ppm):** A characteristic peak for **Meningiomas**. * **Myo-inositol (3.5 ppm):** A marker for astrocytes; elevated in **Alzheimer’s disease** and low-grade gliomas.

Q: A 12-year-old boy presents with seizures that have been difficult to control with medication. A CT scan was performed. What is the most likely diagnosis?

Neurocysticercosis. ***Neurocysticercosis*** - Presents with **refractory seizures** in childhood and classic CT findings of **multiple scattered calcified parenchymal lesions** distributed throughout the cerebral parenchyma. - The calcifications represent **dead/calcified cysticerci** (larval cysts of Taenia solium) and are typically **round, small, and widespread** throughout the brain parenchyma. - Clinical features include **seizures** as the most common presentation, and the condition is caused by ingestion of Taenia solium eggs. *Tuberous sclerosis* - CT shows characteristic **subependymal calcified nodules lining the lateral ventricles** and **cortical tubers**, not scattered parenchymal calcifications. - Clinical triad includes **seizures**, **intellectual disability**, and characteristic **skin lesions** like adenoma sebaceum. *Sturge Weber Syndrome* - CT shows characteristic **tram-track calcifications** in the parieto-occipital cortex, not scattered parenchymal nodules. - Associated with **port-wine stain** facial nevus and **glaucoma**, which are not mentioned in this case. *Von Hippel-Lindau Syndrome* - Primarily affects adults with **cerebellar hemangioblastomas** and **renal cell carcinomas**. - **Seizures are rare** in this condition, and it typically presents later in life, not in childhood.

Question 1

What is the characteristic MRI brain appearance described as a 'soap bubble'?

Accepted Answer

Cryptococcosis

Answer

Neurocysticercosis

Answer

Tuberculosis

Answer

Toxoplasmosis

Question 2

Which of the following tend to show marked and homogeneous enhancement on Gd-DTPA enhanced MRI?

Accepted Answer

Meningiomas and acoustic neuromas

Answer

Oligodendrogliomas and Metastases

Answer

Meningiomas and low grade gliomas

Answer

Glioblastoma multiformes and acoustic neuromas

Question 3

A patient was diagnosed with intracranial cavernous angioma on MR scan. What MRI finding is characteristic of this lesion?

Accepted Answer

Popcorn-like lesion

Answer

Well-defined nidus

Answer

Definite arterial feeders

Answer

Phlebectasis

Question 4

What is the stage of neurocysticercosis characterized by a visible cyst with a scolex and minimal edema?

Accepted Answer

Vesicular

Answer

Colloidal

Answer

Granular

Answer

Calcific nodular

Question 5

A 40-year-old female patient presented with recurrent headaches. MRI showed an extra-axial, dural-based, and enhancing lesion. What is the most likely diagnosis?

Accepted Answer

Meningioma

Answer

Glioma

Answer

Schwannoma

Answer

Pituitary adenoma

Question 6

Which of the following lesions characteristically shows a biconvex shape on CT scan?

Accepted Answer

Epidural hematoma

Answer

Subdural hematoma

Answer

Both

Answer

None

Question 7

Bilateral symmetrical basal ganglia calcification is seen with which condition?

Accepted Answer

Fahr's disease

Answer

Wilson's Disease

Answer

Cytomegalovirus (CMV)

Answer

Toxoplasmosis

Question 8

On MR-spectroscopy, what peak is typically seen at 3.2 ppm?

Accepted Answer

Choline

Answer

Lipid lactate

Answer

N-acetyl aspartate

Answer

Creatinine

Question 9

A 12-year-old boy presents with seizures that have been difficult to control with medication. A CT scan was performed. What is the most likely diagnosis?

Accepted Answer

Neurocysticercosis

Answer

Tuberous sclerosis

Answer

Sturge Weber Syndrome

Answer

Von Hippel-Lindau Syndrome

Question 10

A 10-year-old boy presents with gelastic seizures and precocious puberty. Examination reveals no focal neurological deficits. NCCT shows a soft tissue density nodule in the hypothalamic region. CEMRI is performed to characterize the lesion. What is the most probable diagnosis?

Accepted Answer

Hypothalamic hamartoma

Answer

Hypothalamic astrocytoma

Answer

Craniopharyngioma

Answer

Germinoma

Neuroradiology — MCQs

Neuroradiology — MCQs

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