Neuroradiology Practice Questions

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).

Q: Which CT view is best for evaluating paranasal sinus polyps?

Coronal. **Explanation:** The **Coronal view** is the gold standard for evaluating the paranasal sinuses (PNS), particularly for inflammatory conditions like polyps. This is because the coronal plane provides an anatomical perspective that mimics the surgical approach used in Functional Endoscopic Sinus Surgery (FESS). It is the best view for visualizing the **Osteomeatal Complex (OMC)**—the critical drainage pathway for the frontal, maxillary, and anterior ethmoid sinuses—and for assessing the relationship of polyps to the skull base (cribriform plate) and the medial orbital wall. **Analysis of Options:** * **Axial View:** While excellent for evaluating the anterior and posterior walls of the frontal/sphenoid sinuses and the relationship of the optic nerve to the posterior ethmoid cells, it is less effective for visualizing the vertical drainage pathways and the roof of the ethmoid sinuses. * **Sagittal View:** Primarily used to assess the frontal sinus outflow tract and the extent of disease along the anterior-posterior axis, but it is not the primary diagnostic plane for polyps. * **3D Reconstruction:** Useful for complex maxillofacial trauma or preoperative planning for extensive tumors, but it lacks the internal mucosal detail required to characterize simple polyps. **High-Yield Clinical Pearls for NEET-PG:** * **PNS CT Protocol:** Usually performed as a non-contrast study (NCCT) with thin sections (≤1-2 mm). * **Haller Cells:** Infraorbital ethmoid air cells seen on coronal views; if enlarged, they can narrow the maxillary ostium. * **Onodi Cells:** Sphenoethmoidal cells (best seen on axial/sagittal) that lie lateral or superior to the sphenoid sinus, placing the optic nerve at risk during surgery. * **Antrochoanal Polyp:** A specific type of polyp that originates in the maxillary sinus and extends through the ostium into the choana; the coronal view best demonstrates its "dumbbell" shape.

Q: What is your diagnosis in this infant who was found to have hydrocephalus?

Dandy-Walker malformation. ***Dandy-Walker malformation*** - Characterized by **posterior fossa cyst**, **cerebellar vermis hypoplasia**, and **elevated tentorium** with associated hydrocephalus in infants. - Classic triad includes **cystic dilatation of fourth ventricle**, **absent or hypoplastic cerebellar vermis**, and **enlarged posterior fossa**. *Chiari malformation* - Features **cerebellar tonsillar herniation** through the foramen magnum, not posterior fossa cystic changes. - Type I typically presents in adolescents/adults with **headaches** and **syringomyelia**, while Type II involves **myelomeningocele**. *Vein of Galen malformation* - Presents as **arteriovenous malformation** in the **quadrigeminal cistern** with high-flow vascular lesion. - Causes hydrocephalus due to **mass effect** and **venous obstruction**, but lacks cerebellar vermis abnormalities. *Holoprosencephaly* - Involves **failure of forebrain division** resulting in **absent or incomplete interhemispheric fissure**. - Associated with **facial dysmorphism** and **monoventricle formation**, not posterior fossa abnormalities.

Q: Dumb-bell appearance of spinal cord tumours is seen in which of the following?

Neurofibroma. **Explanation:** The **"Dumb-bell" (or hourglass) appearance** is a classic radiological sign of a **Neurofibroma** (or Schwannoma). These are nerve sheath tumors that arise from the spinal nerve roots. As the tumor grows, it expands within the spinal canal (intradural-extramedullary component) and extends through the narrow intervertebral foramen into the paravertebral space. This constriction by the bony foramen creates the characteristic "waist," resulting in a dumb-bell shape. On imaging, this is often associated with the widening of the intervertebral foramen and erosion of adjacent pedicles. **Analysis of Incorrect Options:** * **Astrocytoma:** These are **intramedullary** tumors (arising within the cord substance). They typically cause focal or diffuse cord expansion rather than extending through the foramina. * **Meningioma:** While these are common intradural-extramedullary tumors, they are usually well-circumscribed, globular, and often show a "dural tail" sign. They rarely extend through the foramen to form a dumb-bell shape. * **Glioblastoma:** This is a high-grade primary malignancy, usually intracranial. Spinal glioblastomas are rare, intramedullary, and highly infiltrative, not presenting with a dumb-bell configuration. **NEET-PG High-Yield Pearls:** * **Most common cause of Dumb-bell tumor:** Schwannoma (more common than Neurofibroma). * **Location:** Neurofibromas are typically **Intradural-Extramedullary**. * **Radiological Sign:** Look for **widening of the neural foramen** on a plain X-ray or CT. * **Association:** Multiple neurofibromas are strongly associated with **Neurofibromatosis Type 1 (NF1)**.

Q: "Lemon sign" and "Banana sign" on Antenatal Ultrasound are seen in which condition?

Chiari Malformation. **Explanation:** The **Lemon sign** and **Banana sign** are classic sonographic markers of **Arnold-Chiari Malformation Type II**, typically associated with open neural tube defects (like myelomeningocele). * **Lemon Sign:** This refers to the scalloping or flattening of the frontal bones of the fetal skull, giving it a lemon-like shape. It occurs due to low intraspinal pressure causing a downward shift of the brain, which leads to a decrease in intracranial pressure and subsequent inward collapse of the frontal bones. * **Banana Sign:** This refers to the characteristic shape of the cerebellum. As the hindbrain herniates through the foramen magnum (caudal displacement), the cerebellum becomes compressed and curved around the brainstem, losing its usual "dumbbell" shape and appearing like a banana. This is often associated with obliteration of the **Cisterna Magna**. **Analysis of Incorrect Options:** * **A. Down Syndrome (Trisomy 21):** Associated with markers like increased Nuchal Translucency (NT), absent nasal bone, echogenic intracardiac focus, and duodenal atresia ("Double bubble sign"). * **C. Turner Syndrome (45, XO):** Characteristically associated with **Cystic Hygroma** and increased NT. * **D. Klinefelter Syndrome (47, XXY):** Usually does not present with specific structural anomalies on routine antenatal ultrasound. **High-Yield Clinical Pearls for NEET-PG:** * The **Lemon sign** is most reliable in the second trimester (before 24 weeks) and may disappear as the skull ossifies. * The **Banana sign** is a more specific and sensitive predictor of spina bifida than the lemon sign. * **Ventriculomegaly** (hydrocephalus) is the most common associated finding in Chiari II malformations.

Q: What is the first investigation of choice for a spinal cord tumor?

MRI. **Explanation:** **MRI (Magnetic Resonance Imaging)** is the investigation of choice for spinal cord tumors due to its superior **soft-tissue contrast resolution** and multiplanar imaging capabilities. It allows for the precise localization of tumors into three categories: intramedullary (within the cord), extramedullary-intradural, and extradural. MRI is highly sensitive in detecting cord edema, syrinx formation, and the relationship of the tumor to the spinal cord and nerve roots. **Gadolinium-enhanced MRI** is specifically used to further characterize the lesion and define its vascularity. **Why other options are incorrect:** * **Myelography:** Once the gold standard, it is now obsolete. It is invasive (requiring lumbar puncture and contrast injection) and provides indirect evidence of a tumor (e.g., a filling defect) without showing the internal architecture of the cord. * **CT Scan:** While excellent for evaluating bony anatomy and calcifications, CT has poor soft-tissue resolution for the spinal cord and is limited by "bone-hardening" artifacts within the spinal canal. * **Plain X-ray:** This is often the initial screening tool for back pain but is insensitive for soft tissue. It only shows secondary signs like pedicle erosion (Winking Owl sign), vertebral destruction, or widening of the interpedicular distance. **Clinical Pearls for NEET-PG:** * **Most common intramedullary tumor:** Ependymoma (Adults), Astrocytoma (Children). * **Most common intradural-extramedullary tumors:** Nerve sheath tumors (Schwannoma/Neurofibroma) and Meningiomas. * **Drop Metastasis:** MRI of the entire neuraxis is required for tumors like Medulloblastoma or Ependymoma. * **Investigation of choice for Spinal Trauma:** Non-contrast CT (to check for fractures); however, MRI is used to assess cord injury.

Q: A neonate presents with a left-to-right shunt and high cardiac output heart failure. CT angiography of the neonate is shown. What is the diagnosis?

Vein of Galen malformation. ***Vein of Galen malformation*** - Causes **left-to-right arteriovenous shunting** that directly leads to **high-output cardiac failure** in neonates due to the large volume of blood bypassing normal capillary resistance. - CT angiography typically shows a **dilated midline venous structure** in the posterior third ventricle region with prominent **feeding arteries** and **venous drainage**. *Sagittal venous thrombosis* - Would present with **venous stasis** and **increased intracranial pressure**, not left-to-right shunting or cardiac failure. - CT angiography shows **absent flow** in the superior sagittal sinus with possible **venous infarcts**, not arteriovenous connections. *Intracranial hemorrhage* - Presents with **mass effect** and **neurological deterioration**, not cardiac symptoms or shunting. - CT shows **hyperdense blood products** in brain parenchyma, ventricles, or subarachnoid space, not vascular malformations. *Arnold-Chiari malformation* - A **structural brain malformation** involving **cerebellar tonsillar herniation** through the foramen magnum. - Does not cause **cardiac failure** or **arteriovenous shunting**, and appears as **posterior fossa crowding** on imaging.

Q: Calcification of the Posterior Longitudinal Ligament is best diagnosed by which imaging modality?

CT. **Explanation:** **Ossification of the Posterior Longitudinal Ligament (OPLL)** is a condition where the ligament becomes progressively calcified, potentially leading to spinal canal stenosis and myelopathy. 1. **Why CT is the Correct Answer:** Computed Tomography (CT) is the **gold standard** for diagnosing OPLL. It has superior spatial resolution for bone and mineralized tissues. CT can precisely characterize the thickness, extent, and morphology of the calcification (e.g., continuous, segmental, or circumscribed types). It is essential for surgical planning to determine the degree of canal narrowing and the presence of the "double-layer sign," which indicates dural involvement. 2. **Why Other Options are Incorrect:** * **X-Ray:** While large calcifications may be visible on a lateral view, X-rays lack the sensitivity to detect early ossification and cannot accurately assess the degree of spinal canal compromise due to overlying bony shadows. * **MRI:** MRI is the best modality for evaluating the **spinal cord** (detecting myelomalacia or edema), but it is notoriously poor at visualizing cortical bone or calcification. On MRI, OPLL appears as a "signal void" (dark), which can be easily confused with a simple disc herniation or osteophytes. * **PET:** This is a functional imaging modality used primarily for oncology and inflammation; it has no role in the structural diagnosis of ligamentous calcification. **High-Yield Pearls for NEET-PG:** * **Most Common Site:** Cervical spine (specifically C4–C6). * **Epidemiology:** Most common in the East Asian population (traditionally called "Japanese disease"). * **Clinical Presentation:** Often presents with **Cervical Spondylotic Myelopathy** (gait instability, hand clumsiness). * **Radiological Sign:** Look for a dense radio-opaque band posterior to the vertebral bodies on a CT scan.

Q: Which of the following is FALSE regarding Dandy-Walker malformation?

Microcephaly. **Explanation:** **Dandy-Walker Malformation (DWM)** is a congenital posterior fossa anomaly characterized by a specific triad: hypoplasia/agenesis of the cerebellar vermis, cystic dilatation of the fourth ventricle, and an enlarged posterior fossa with upward displacement of the tentorium and torcula. **Why Microcephaly is the correct (False) option:** In DWM, the massive cystic expansion of the fourth ventricle and the resulting obstructive hydrocephalus typically lead to **macrocephaly** (enlarged head circumference) and bulging fontanelles in infants. Microcephaly is not a feature of DWM; rather, it is associated with conditions like TORCH infections or Zika virus. **Analysis of other options:** * **Hypoplasia of the vermis:** This is the hallmark anatomical defect. The vermis is often rotated superiorly and is incomplete. * **Hydrocephalus:** Occurs in approximately 70-90% of patients due to atresia of the Foramina of Luschka and Magendie or associated aqueductal stenosis. * **Ataxia:** Since the cerebellum (responsible for coordination) is malformed, patients commonly present with developmental delay, hypotonia, and cerebellar ataxia. **NEET-PG High-Yield Pearls:** * **Classic Triad:** 1. Vermian hypoplasia, 2. Cystic 4th ventricle, 3. Enlarged posterior fossa. * **Torcular-Herophili sign:** The confluence of sinuses (torcula) is displaced upwards (above the level of the lambdoid suture) due to the large cyst. * **Associated Anomalies:** Agenesis of the corpus callosum is the most common associated CNS finding. * **Differential Diagnosis:** Mega Cisterna Magna (normal vermis and 4th ventricle) and Arachnoid Cyst (mass effect on a normal cerebellum).

Question 1

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

Accepted Answer

Meningioma

Answer

Ependymoma

Answer

CNS lymphoma

Answer

Medulloblastoma

Question 2

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

Accepted Answer

CT scan

Answer

MRI

Answer

USG

Answer

Contrast study

Question 3

Which CT view is best for evaluating paranasal sinus polyps?

Accepted Answer

Coronal

Answer

Axial

Answer

Sagittal

Answer

3D reconstruction

Question 4

What is your diagnosis in this infant who was found to have hydrocephalus?

Accepted Answer

Dandy-Walker malformation

Answer

Chiari malformation

Answer

Vein of Galen malformation

Answer

Holoprosencephaly

Question 5

Dumb-bell appearance of spinal cord tumours is seen in which of the following?

Accepted Answer

Neurofibroma

Answer

Astrocytoma

Answer

Meningioma

Answer

Glioblastoma

Question 6

"Lemon sign" and "Banana sign" on Antenatal Ultrasound are seen in which condition?

Accepted Answer

Chiari Malformation

Answer

Down syndrome

Answer

Turner syndrome

Answer

Klinefelter syndrome

Question 7

What is the first investigation of choice for a spinal cord tumor?

Accepted Answer

MRI

Answer

Myelography

Answer

CT scan

Answer

Plain X-ray

Question 8

A neonate presents with a left-to-right shunt and high cardiac output heart failure. CT angiography of the neonate is shown. What is the diagnosis?

Accepted Answer

Vein of Galen malformation

Answer

Sagittal venous thrombosis

Answer

Intracranial hemorrhage

Answer

Arnold-Chiari malformation

Question 9

Calcification of the Posterior Longitudinal Ligament is best diagnosed by which imaging modality?

Accepted Answer

CT

Answer

X-Ray

Answer

MRI

Answer

PET

Question 10

Which of the following is FALSE regarding Dandy-Walker malformation?

Accepted Answer

Microcephaly

Answer

Hypoplasia of the vermis

Answer

Hydrocephalus

Answer

Ataxia

Neuroradiology — MCQs

Neuroradiology — MCQs

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