Neuroradiology Practice Questions

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.

Q: Intracranial calcification is best diagnosed by?

CT Scan. **Explanation:** **1. Why CT Scan is the Correct Answer:** Computed Tomography (CT) is the **gold standard** for detecting intracranial calcification. This is because CT is highly sensitive to the high electron density of calcium, which causes significant attenuation of the X-ray beam. On a CT scan, calcium appears as a bright, hyperdense (white) area with high Hounsfield Units (HU), typically ranging from **+100 to over +1000 HU**. It can detect even minute, punctate calcifications that other modalities might miss. **2. Why Other Options are Incorrect:** * **Plain X-ray Skull:** While X-rays can show large calcifications (like a calcified pineal gland), they lack the sensitivity and spatial resolution to detect small or deep-seated lesions. It is largely obsolete for this purpose. * **FDG-PET Scan:** This is a functional imaging modality used to assess glucose metabolism (e.g., in tumors or epilepsy). It does not provide structural detail regarding mineralization. * **MRI:** MRI is generally **inferior** to CT for identifying calcium. On standard sequences (T1/T2), calcium can have variable appearances (often dark/hypointense), making it difficult to distinguish from flowing blood (flow voids) or air. While specialized sequences like **SWI (Susceptibility Weighted Imaging)** are sensitive to calcium, CT remains the diagnostic benchmark. **High-Yield Clinical Pearls for NEET-PG:** * **Most common physiological intracranial calcification:** Pineal gland (seen in >50% of adults). * **Sturge-Weber Syndrome:** Characterized by "tram-track" cortical calcification. * **Oligodendroglioma:** The brain tumor most famously associated with calcification (70-90% of cases). * **Fahr’s Disease:** Idiopathic, massive bilateral basal ganglia calcification. * **TORCH Infections:** CMV typically causes **periventricular** calcification, while Toxoplasmosis causes **scattered/diffuse** parenchymal calcification.

Q: Which of the following is NOT a typical finding of neurocysticercosis on CT scan?

High density lesions. **Explanation:** Neurocysticercosis (NCC), caused by the larval stage of *Taenia solium*, presents with varying imaging features depending on the stage of the parasite's life cycle. **Why "High density lesions" is the correct answer:** On a non-contrast CT (NCCT), NCC typically presents as either low-density (cystic) or calcified lesions. **High-density (hyperdense) lesions** are not a characteristic feature of NCC. While the scolex within a cyst may appear as a tiny hyperdense dot ("hole-with-dot" appearance), the lesion itself is not inherently high-density. Hyperdense lesions on CT usually suggest acute hemorrhage or highly cellular tumors, neither of which are typical for NCC. **Analysis of incorrect options:** * **Parenchymal calcification:** This is the most common finding in the **nodular calcified stage** (final stage), representing the death of the parasite. * **Low density non-enhancing lesion:** This corresponds to the **vesicular stage**, where the viable parasite lives inside a fluid-filled cyst that has a density similar to CSF. * **Diffuse cerebral edema:** This occurs during the **encephalitic form** of NCC, usually due to a heavy parasitic load triggering a massive host immune response, or during the colloidal vesicular stage where localized edema is common. **NEET-PG High-Yield Pearls:** * **Stages of NCC:** Vesicular (Cyst with scolex) → Colloidal vesicular (Ring enhancement + Edema) → Granular nodular (Decreasing edema) → Nodular calcified (Calcified speck). * **Pathognomonic finding:** A cystic lesion with an eccentric hyperdense scolex (**"Hole-with-dot" sign**). * **Drug of Choice:** Albendazole is preferred over Praziquantel due to better CNS penetration. Steroids must be administered before antiparasitic drugs to prevent inflammation-induced seizures.

Q: Pepper pot appearance of the skull is seen in which of the following conditions?

Hyperparathyroidism. **Explanation:** **Hyperparathyroidism (Correct Answer):** The "Pepper pot skull" (also known as the **salt-and-pepper skull**) is a classic radiologic sign of **Hyperparathyroidism** (primary, secondary, or tertiary). It occurs due to increased parathyroid hormone (PTH) levels, which stimulate osteoclastic activity. This leads to multiple small, diffuse, punctate lucencies (resorption) interspersed with areas of normal bone density, creating a mottled appearance. **Analysis of Incorrect Options:** * **Multiple Myeloma:** Characterized by **"Raindrop skull"** or "punched-out" lesions. Unlike the diffuse mottling of hyperparathyroidism, these are well-circumscribed, sharp, non-sclerotic lytic lesions of varying sizes. * **Sickle Cell Anemia:** Characterized by a **"Hair-on-end"** appearance. This results from compensatory extramedullary hematopoiesis causing widening of the diploic space and thinning of the outer table with vertical striations. * **Fibrous Dysplasia:** Classically shows a **"Ground-glass"** appearance on X-ray/CT. It involves the replacement of normal bone with fibrous tissue, often causing expansion of the bone and a smoky, hazy density. **High-Yield Clinical Pearls for NEET-PG:** * **Subperiosteal bone resorption** (especially on the radial aspect of the middle phalanges) is the *most sensitive* and pathognomonic sign of hyperparathyroidism. * Other skeletal features of hyperparathyroidism include **Brown tumors** (osteoclastomas) and the **Rugger-jersey spine** (seen in renal osteodystrophy). * **Distinction:** Pepper pot = Hyperparathyroidism; Punched-out/Raindrop = Multiple Myeloma.

Q: Tigroid white matter is characteristically seen on MR spectroscopy in which of the following conditions?

Pelizaeus-Merzbacher disease. **Explanation:** The **"Tigroid" appearance** (or leopard-skin pattern) is a classic radiological sign characterized by linear or punctate areas of preserved myelin (darker signal) against a background of diffuse demyelination (brighter signal) in the white matter. **1. Why Pelizaeus-Merzbacher Disease (PMD) is correct:** PMD is an X-linked recessive **hypomyelinating leukodystrophy** caused by mutations in the **PLP1 gene**. The "Tigroid" pattern occurs because of islands of relatively preserved myelin around the perivascular spaces amidst a sea of deficient myelin. While this pattern is most famously associated with **Metachromatic Leukodystrophy (MLD)**, it is also a hallmark of PMD. *Note: The question mentions MR Spectroscopy; however, the "Tigroid" pattern is primarily a structural MRI finding (T2/FLAIR). In PMD, spectroscopy typically shows reduced NAA and elevated choline/myo-inositol.* **2. Why the other options are incorrect:** * **Pantothenate kinase deficiency (PKAN):** Characterized by the **"Eye of the Tiger"** sign (central T2 hyperintensity surrounded by hypointense hemosiderin) in the globus pallidus, not a tigroid white matter pattern. * **Neuroferritinopathy & Aceruloplasminemia:** These are disorders of iron metabolism (NBIA). They present with iron deposition in the basal ganglia (T2 hypointensity) rather than the specific white matter sparing seen in PMD. **Clinical Pearls for NEET-PG:** * **Tigroid Pattern:** Seen in **Metachromatic Leukodystrophy (MLD)** and **Pelizaeus-Merzbacher Disease (PMD)**. * **Eye of the Tiger:** Pathognomonic for **PKAN**. * **Macrocephaly + Leukodystrophy:** Think **Canavan disease** (elevated NAA on spectroscopy) or **Alexander disease** (frontal predominance). * **PMD Clinical Triad:** Nystagmus, spasticity, and developmental delay in an infant male.

Q: A CT scan of the neck is shown below with an arrow pointing towards the upper cervical vertebrae. What does the arrow most likely indicate?

Cervical spine injury. ***Cervical spine injury*** - CT scan showing abnormal findings at the **upper cervical vertebrae** with an arrow pointing to the area suggests **traumatic injury** or **fracture**. - Upper cervical spine injuries (C1-C2) are critical and can involve **atlantoaxial dislocation** or **odontoid fractures** requiring immediate evaluation. *Calcification of the posterior longitudinal ligament* - **OPLL (Ossification of Posterior Longitudinal Ligament)** typically appears as **continuous calcified bands** along the posterior vertebral bodies. - More commonly seen in the **lower cervical spine** (C5-C6) and presents as **chronic degenerative changes**, not acute findings. *Normal CT findings* - Normal cervical spine CT shows **intact vertebral bodies**, **clear joint spaces**, and **normal alignment** without abnormal densities. - The presence of an arrow indicating a specific finding suggests **pathological changes** rather than normal anatomy. *Vascular lesion* - Vascular abnormalities like **arteriovenous malformations** or **aneurysms** would show **contrast enhancement** on CT angiography. - Typically appear as **serpentine structures** or **abnormal vessel patterns**, not as bony abnormalities in the cervical spine.

Q: The salt and pepper effect in MRI of the salivary gland is characteristic of which condition?

Sjogren syndrome. **Explanation:** The **"salt and pepper" appearance** on MRI of the parotid and submandibular glands is a classic imaging hallmark of **Sjogren Syndrome**. 1. **Why Sjogren Syndrome is correct:** This appearance is caused by the chronic inflammatory process of the disease. The **"pepper" (dark spots)** represents areas of punctate calcification, fibrosis, or hemosiderin deposits. The **"salt" (bright spots)** represents areas of fatty replacement, focal lymphocytic infiltration, or small cystic dilatations of the salivary ducts (sialectasis). On T2-weighted images, the heterogeneous mixture of high-signal intensity (fluid/fat) and low-signal intensity (fibrosis/calcification) creates this characteristic mottled pattern. 2. **Why other options are incorrect:** * **Thalassemia & Sickle Cell Anemia:** These conditions are associated with "salt and pepper" appearance in the **skull vault (calvaria)** on X-ray/CT due to marrow hyperplasia and trabecular changes, not in the salivary glands on MRI. * **Condensing Osteitis:** This is a periapical inflammatory bone reaction (sclerotic bone) usually found at the root apex of a tooth; it does not involve salivary gland parenchyma. **NEET-PG High-Yield Pearls:** * **Sjogren Syndrome:** Look for the clinical triad of dry eyes (xerophthalmia), dry mouth (xerostomia), and a connective tissue disease (e.g., Rheumatoid Arthritis). * **Imaging Gold Standard:** While MRI shows the salt and pepper sign, **Sialography** (traditionally) shows a "cherry blossom" or "leafless tree" appearance due to globular sialectasis. * **Differential Diagnosis:** The "salt and pepper" sign is also classically used to describe **Glomus tumors (Paragangliomas)** on MRI, where the "pepper" represents high-flow vascular void streaks. Always correlate with the anatomical location mentioned in the question.

Question 1

What is not a feature of Sturge-Weber syndrome?

Accepted Answer

Empty sella

Answer

Rail track appearance

Answer

Hemiatrophy of the brain

Answer

Convulsion

Question 2

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

Question 3

A 64-year-old man presents with headache and left-sided upper extremity weakness. The MRI of the brain is shown. What does the MRI exhibit?

Accepted Answer

The lesion shows a ring pattern of enhancement with intravenous contrast and has a nonenhancing necrotic center.

Answer

The lesion is regular in shape.

Answer

The lesion is well demarcated from surrounding brain tissue.

Answer

The lesion shows an absence of surrounding white-matter edema.

Question 4

Intracranial calcification is best diagnosed by?

Accepted Answer

CT Scan

Answer

Plain X-ray skull

Answer

FDG-PET Scan

Answer

MRI

Question 5

Which of the following is NOT a typical finding of neurocysticercosis on CT scan?

Accepted Answer

High density lesions

Answer

Parenchymal calcification

Answer

Low density non-enhancing lesion

Answer

Diffuse cerebral edema

Question 6

Pepper pot appearance of the skull is seen in which of the following conditions?

Accepted Answer

Hyperparathyroidism

Answer

Multiple myeloma

Answer

Sickle cell anemia

Answer

Fibrous dysplasia

Question 7

Tigroid white matter is characteristically seen on MR spectroscopy in which of the following conditions?

Accepted Answer

Pelizaeus-Merzbacher disease

Answer

Pantothenate kinase deficiency

Answer

Neuroferritinopathy

Answer

Aceruloplasminemia

Question 8

A CT scan of the neck is shown below with an arrow pointing towards the upper cervical vertebrae. What does the arrow most likely indicate?

Accepted Answer

Cervical spine injury

Answer

Calcification of the posterior longitudinal ligament

Answer

Normal CT findings

Answer

Vascular lesion

Question 9

The salt and pepper effect in MRI of the salivary gland is characteristic of which condition?

Accepted Answer

Sjogren syndrome

Answer

Thalassemia

Answer

Sickle cell anemia

Answer

Condensing osteitis

Question 10

Which of the following is not a cause of communicating hydrocephalus?

Accepted Answer

Vein of Galen malformation

Answer

Choroid plexus papilloma

Answer

Achondroplasia

Answer

Meningeal metastasis

Neuroradiology — MCQs

Neuroradiology — MCQs

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