Neuroradiology Practice Questions

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: What is the best imaging modality for Pelizaeus-Merzbacher disease?

MRI. **Explanation:** **Pelizaeus-Merzbacher Disease (PMD)** is a rare X-linked recessive leukodystrophy characterized by a defect in myelin formation (hypomyelination) due to mutations in the **PLP1 gene**. **Why MRI is the Correct Answer:** MRI is the gold standard and the most sensitive modality for diagnosing PMD. Because the primary pathology is a failure of normal myelination, MRI can visualize the lack of white matter maturation. The characteristic finding is a **"tigroid" pattern** or diffuse, symmetrical T2 hyperintensity throughout the white matter, representing a permanent state of neonatal-like hypomyelination. MRI is superior because it provides high soft-tissue contrast necessary to distinguish between gray and white matter development. **Why Other Options are Incorrect:** * **X-ray:** Primarily visualizes bone; it cannot evaluate white matter or brain parenchyma. * **Ultrasound (USG):** While useful in neonates through the open fontanelle, it lacks the resolution to detect specific white matter signal changes required for a leukodystrophy diagnosis. * **CT Scan:** CT is poor at evaluating white matter maturation. While it may show non-specific atrophy in late stages, it cannot detect the subtle hypomyelination patterns seen on MRI. **High-Yield Clinical Pearls for NEET-PG:** * **Pathognomonic MRI Sign:** Diffuse T2 hyperintensity (hypomyelination) with a "tigroid" appearance (sparing of perivascular myelin islands). * **Clinical Triad:** Nystagmus (often rotary), developmental delay, and progressive spasticity. * **Biochemical Defect:** Mutation in the Proteolipid Protein 1 (PLP1) gene. * **MRS Finding:** Usually shows relatively preserved N-acetylaspartate (NAA) levels compared to other demyelinating diseases.

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.

Q: A biconvex hyperdense shadow on a non-contrast CT scan is typically seen in which of the following conditions?

Extradural hemorrhage. ### Explanation The correct answer is **Extradural Hemorrhage (EDH)**. **1. Why Extradural Hemorrhage is Correct:** An EDH occurs due to bleeding into the potential space between the skull and the dura mater, most commonly following a fracture of the temporal bone and rupture of the **middle meningeal artery**. Because the dura is firmly attached to the skull sutures, the expanding hematoma is restricted at these points. This pressure forces the blood to expand inward toward the brain, creating a characteristic **biconvex (lentiform or lemon-shaped)**, hyperdense (white) appearance on a non-contrast CT (NCCT). **2. Why the Other Options are Incorrect:** * **Subdural Hemorrhage (SDH):** This occurs between the dura and the arachnoid mater, usually due to the tearing of **bridging veins**. Since this space is not limited by sutures, the blood spreads widely along the brain's convexity, resulting in a **crescent-shaped (concave)** appearance. * **Subarachnoid Hemorrhage (SAH):** This involves bleeding into the subarachnoid space (between the arachnoid and pia mater). On NCCT, it appears as hyperdensity within the **sulci, fissures, and basal cisterns** (often described as a "star-shaped" density in the circle of Willis). * **Intraventricular Hemorrhage (IVH):** This refers to blood within the brain's ventricular system, appearing as hyperdense fluid-levels within the lateral, third, or fourth ventricles. **3. High-Yield Clinical Pearls for NEET-PG:** * **Lucid Interval:** Classically associated with EDH (the patient regains consciousness before deteriorating). * **Suture Lines:** EDH **does not** cross suture lines (but can cross the midline/dural attachments), whereas SDH **does** cross suture lines but not dural attachments (like the falx). * **Source of Bleed:** EDH is usually arterial (Middle Meningeal Artery); SDH is usually venous (Bridging Veins).

Q: Boomerang ventricle is a feature of?

Holoprosencephaly. ### Explanation **Correct Answer: C. Holoprosencephaly** **Understanding the Concept:** Holoprosencephaly (HPE) is a spectrum of forebrain malformations resulting from the failure of the embryonic prosencephalon to divide into two cerebral hemispheres. The **"Boomerang Ventricle"** (also known as a monoventricle) is a hallmark of the most severe form, **Alobar Holoprosencephaly**. In this condition, the absence of the midline structures (like the septum pellucidum and falx cerebri) leads to a single, large, horseshoe or boomerang-shaped ventricular cavity that communicates across the midline. **Analysis of Incorrect Options:** * **Lissencephaly:** Characterized by a "smooth brain" due to failure of neuronal migration. Key radiological signs include a **"Figure-of-8" appearance** (due to wide Sylvian fissures) and a thickened cortex, but not a monoventricle. * **Schizencephaly:** A gray matter-lined cleft extending from the ependyma to the pial surface. While it affects the ventricles (often showing a "pointy" appearance at the site of the cleft), it does not create a single boomerang-shaped cavity. * **Huntington’s Chorea:** This neurodegenerative disorder causes atrophy of the **caudate nucleus**. This leads to compensatory enlargement of the lateral ventricles, giving them a **"Box-car" appearance**, rather than a boomerang shape. **Clinical Pearls for NEET-PG:** * **HPE Spectrum:** Alobar (most severe, monoventricle) → Semilobar → Lobar (least severe). * **Associated Sign:** "Face predicts the brain"—HPE is frequently associated with midline facial defects like cyclopia, proboscis, or cleft lip/palate. * **Key Association:** Strongly linked with **Trisomy 13 (Patau Syndrome)**. * **Radiology Tip:** Look for the absence of the **Septum Pellucidum**; if it is missing, always consider the HPE spectrum or Septo-optic Dysplasia.

Question 1

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 2

Intracranial calcification is best diagnosed by?

Accepted Answer

CT Scan

Answer

Plain X-ray skull

Answer

FDG-PET Scan

Answer

MRI

Question 3

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 4

What is the best imaging modality for Pelizaeus-Merzbacher disease?

Accepted Answer

MRI

Answer

X-ray

Answer

Ultrasound (USG)

Answer

CT scan

Question 5

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 6

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 7

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 8

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

Question 9

A biconvex hyperdense shadow on a non-contrast CT scan is typically seen in which of the following conditions?

Accepted Answer

Extradural hemorrhage

Answer

Subdural hemorrhage

Answer

Subarachnoid hemorrhage

Answer

Intraventricular hemorrhage

Question 10

Boomerang ventricle is a feature of?

Accepted Answer

Holoprosencephaly

Answer

Lissencephaly

Answer

Schizencephaly

Answer

Huntington's Chorea

Neuroradiology — MCQs

Neuroradiology — MCQs

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