Neuroradiology — MCQs

A 47-year-old female presents with a 2-year history of headache, changes in vision, and seizures. She has recently developed unilateral weakness. A CT scan revealed a well-circumscribed mass abutting the skull in the left hemisphere. Contrast-enhanced MRI confirms the findings. What is the next step in management?

Q275Easy

In which of the following conditions is the alanine peak observed on MR Spectroscopy?

Q276Easy

Tram-like calcifications are seen in which of the following conditions?

Q277Easy

What is the most common tumor of the head that undergoes calcification?

Q278Easy

Intracranial calcifications on skull X-ray can include which of the following?

Q279Medium

A 16-year-old boy complains of headaches for the past 9 months with no prior medical problems. Physical examination reveals no abnormal findings. A CT scan of the head shows enlargement of the lateral cerebral ventricles and third ventricle. Lumbar puncture with normal opening pressure yields clear CSF with slightly elevated protein, normal glucose, and no leukocytes. Which of the following intracranial lesions is most likely to cause these findings?

Q280Easy

What is the investigation of choice for laryngeal cartilage involvement?

Neuroradiology Indian Medical PG Practice Questions and MCQs

Question 271: Which type of aneurysm is typically associated with third nerve palsy?

A. Aneurysm of the cavernous sinus
B. Aneurysm of the middle cerebral artery
C. Aneurysm of the anterior communicating artery
D. Aneurysm at the junction of the posterior cerebral artery and internal carotid artery (Correct Answer)

Explanation: **Explanation:** The correct answer is **D: Aneurysm at the junction of the posterior communicating artery (PCoA) and internal carotid artery (ICA).** **1. Why Option D is Correct:** The **Oculomotor nerve (CN III)** exits the midbrain and passes between the superior cerebellar artery (SCA) and the posterior cerebral artery (PCA). It then runs parallel and lateral to the **Posterior Communicating Artery (PCoA)**. Due to this close anatomical proximity, an aneurysm arising at the junction of the **ICA and PCoA** (often referred to simply as a PCoA aneurysm) can directly compress the nerve. **2. Why Other Options are Incorrect:** * **A. Cavernous Sinus Aneurysm:** While CN III passes through the cavernous sinus, an aneurysm here usually presents with a combination of deficits (CN III, IV, V1, V2, and VI) rather than isolated third nerve palsy. * **B. Middle Cerebral Artery (MCA):** MCA aneurysms are common but are located laterally in the Sylvian fissure, far from the brainstem exit point of the cranial nerves. * **C. Anterior Communicating Artery (ACoA):** These are the most common circle of Willis aneurysms but typically present with visual field defects (due to proximity to the optic chiasm) or frontal lobe symptoms, not CN III palsy. **3. NEET-PG High-Yield Pearls:** * **Pupillary Involvement:** In compressive lesions (like an aneurysm), the **parasympathetic fibers** (which lie superficially on the nerve) are affected first, leading to a **dilated, non-reactive pupil**. This is a surgical emergency. * **Medical vs. Surgical:** Ischemic CN III palsy (e.g., Diabetes) usually **spares the pupil** because the internal fibers are affected, whereas aneurysmal compression **involves the pupil**. * **Rule of Thumb:** Any painful third nerve palsy with pupillary involvement is a **PCoA aneurysm** until proven otherwise by CT Angiography or DSA.

Question 272: A 20-year-old female presents with a mass in the cavernous sinus and 6th cranial nerve palsy. A T2W MRI shows a hyperintense shadow with homogenous contrast enhancement. What is the most likely diagnosis?

A. Schwannoma
B. Meningioma (Correct Answer)
C. Astrocytoma
D. Cavernous sinus hemangioma

Explanation: **Explanation:** The clinical presentation of a cavernous sinus mass associated with a 6th cranial nerve palsy (Abducens nerve) in a young female is highly suggestive of a **Meningioma**. **Why Meningioma is the correct answer:** Meningiomas are the most common primary tumors of the cavernous sinus. On MRI, they typically appear isointense to hypointense on T1W and variable (often hyperintense) on T2W images. Their hallmark feature is **intense, homogenous contrast enhancement** and the presence of a **"dural tail sign."** While they can encase the internal carotid artery (ICA), they often cause narrowing of the vessel lumen, a key differentiating feature from other lesions. **Why other options are incorrect:** * **Schwannoma:** While they can occur in the cavernous sinus (Trigeminal nerve being most common), they typically show heterogeneous enhancement if large and often cause bone remodeling rather than simple encasement. * **Astrocytoma:** These are intra-axial tumors (within the brain parenchyma). The cavernous sinus is an extra-axial space; therefore, an astrocytoma would not primarily arise here. * **Cavernous Sinus Hemangioma:** These are rare and show extremely bright "light-bulb" hyperintensity on T2W images (more so than meningiomas) and progressive filling with contrast, but they are less common than meningiomas in this demographic. **NEET-PG High-Yield Pearls:** * **Meningioma:** Most common extra-axial tumor; associated with Psammoma bodies (histology) and Sunburst appearance (angiography). * **6th Nerve Palsy:** The Abducens nerve is the most vulnerable nerve in the cavernous sinus because it runs centrally (medial) near the ICA, while CN III, IV, and V1/V2 are protected in the lateral wall. * **ICA Encasement:** If a cavernous sinus mass **narrows** the ICA, think Meningioma. If it **expands** the sinus without narrowing the ICA, think Schwannoma or Hemangioma.

Question 273: Which of the following conditions is characterized by the 'racing car sign' on imaging?

A. Lipoma of corpus callosum
B. Agenesis of corpus callosum (Correct Answer)
C. Necrosis of corpus callosum
D. Degeneration of corpus callosum

Explanation: ### Explanation **Agenesis of Corpus Callosum (ACC)** is a congenital anomaly where the white matter tract connecting the two cerebral hemispheres fails to develop. **Why the 'Racing Car Sign' occurs:** In ACC, the absence of the corpus callosum leads to a lack of midline fusion. This causes the **lateral ventricles to become widely separated and oriented parallel** to each other, rather than their normal convergent "V" shape. On **axial** CT or MRI scans, these parallel, non-tapering lateral ventricles resemble the wheels and chassis of a **Formula 1 racing car** (or "steer horn" appearance on coronal views). **Analysis of Incorrect Options:** * **A. Lipoma of corpus callosum:** While often associated with ACC, a lipoma itself appears as a fat-density mass (hypodense on CT, hyperintense on T1 MRI). It does not cause the racing car sign unless ACC is also present. * **C & D. Necrosis/Degeneration:** Conditions like **Marchiafava-Bignami disease** (seen in chronic alcoholics) involve necrosis or atrophy of the corpus callosum. While the structure is damaged or thinned, the developmental architecture of the ventricles remains relatively normal, thus not producing the parallel "racing car" configuration. **High-Yield Facts for NEET-PG:** * **Probst Bundles:** These are longitudinal white matter tracts that run parallel to the interhemispheric fissure in ACC; they represent axons that failed to cross the midline. * **Colpocephaly:** This is the disproportionate enlargement of the occipital horns of the lateral ventricles, commonly seen in ACC. * **Associated Findings:** ACC is frequently associated with **Dandy-Walker malformation**, Chiari II malformation, and interhemispheric cysts. * **Coronal View:** Look for the **"Steer-horn"** or "Viking helmet" appearance of the lateral ventricles.

Question 274: A 47-year-old female presents with a 2-year history of headache, changes in vision, and seizures. She has recently developed unilateral weakness. A CT scan revealed a well-circumscribed mass abutting the skull in the left hemisphere. Contrast-enhanced MRI confirms the findings. What is the next step in management?

A. Surgical excision (Correct Answer)
B. Chemotherapy with Adriamycin
C. Cerebral angiography with tumor embolization
D. Preoperative radiation therapy followed by surgical excision

Explanation: **Explanation:** The clinical presentation and imaging findings are classic for a **Meningioma**. The key features—a well-circumscribed mass abutting the skull (extra-axial), chronic progression (2 years), and symptoms of mass effect (headache, seizures, focal weakness)—point toward this slow-growing, typically benign tumor. **1. Why Surgical Excision is the Correct Answer:** For symptomatic meningiomas, **complete surgical resection (Simpson Grade I)** is the gold standard and primary treatment of choice. It provides immediate relief of mass effect, allows for histopathological confirmation, and is often curative for WHO Grade I tumors. **2. Why the Other Options are Incorrect:** * **B. Chemotherapy:** Meningiomas are generally chemo-resistant. Adriamycin (Doxorubicin) has no established role in the primary management of these tumors. * **C. Cerebral Angiography with Embolization:** While preoperative embolization can be used to reduce intraoperative bleeding in highly vascular tumors, it is an **adjunct**, not the "next step" in definitive management. Surgery remains the primary goal. * **D. Preoperative Radiation:** Radiation is typically reserved for recurrent tumors, subtotal resections, or high-grade (malignant) meningiomas. It is not indicated as a routine preoperative measure for a primary resectable mass. **Clinical Pearls for NEET-PG:** * **MRI Hallmark:** Look for the **"Dural Tail Sign"** (thickening of the dura adjacent to the tumor) and intense, homogenous contrast enhancement. * **Histology:** Characterized by **Psammoma bodies** (laminated calcifications) and whorled patterns of cells. * **Demographics:** More common in females (due to progesterone receptors) and associated with **Neurofibromatosis Type 2 (NF2)**. * **CT Finding:** Often hyperdense on non-contrast CT and may show hyperostosis of the overlying bone.

Question 275: In which of the following conditions is the alanine peak observed on MR Spectroscopy?

A. Tuberculoma
B. Tumors
C. Canavan disease
D. Meningioma (Correct Answer)

Explanation: **Explanation:** Magnetic Resonance Spectroscopy (MRS) is a non-invasive tool used to evaluate the chemical composition of tissues. The presence of an **Alanine peak (at 1.3 - 1.5 ppm)** is a classic diagnostic hallmark for **Meningioma**. 1. **Why Meningioma is correct:** Alanine is an amino acid that typically resonates at 1.47 ppm. In meningiomas, there is a characteristic metabolic shift that results in the accumulation of alanine. On MRS, this often appears as an inverted doublet (at TE 135 ms) or a peak that characterizes this extra-axial tumor, distinguishing it from other mimics like schwannomas. 2. **Why other options are incorrect:** * **Tuberculoma:** Characterized by a massive **Lipid/Lactate peak** (at 0.9 - 1.3 ppm) due to caseous necrosis, along with a decrease in NAA and Choline. * **Tumors (High-grade Gliomas/Metastasis):** These typically show an **elevated Choline peak** (increased cell turnover) and a **decreased NAA peak** (neuronal loss). * **Canavan Disease:** This is a leukodystrophy uniquely characterized by a pathognomonic **elevation of the NAA peak** (N-acetylaspartate) due to a deficiency of the aspartoacylase enzyme. **High-Yield Clinical Pearls for NEET-PG:** * **Alanine (1.47 ppm):** Meningioma. * **NAA (2.0 ppm):** Marker of neuronal integrity (Decreased in most tumors/insults; Increased in Canavan disease). * **Choline (3.2 ppm):** Marker of cell membrane turnover (Increased in malignancy). * **Lactate (1.3 ppm):** Indicates anaerobic metabolism (Inverted doublet at TE 135; seen in infarcts, abscesses, and high-grade tumors). * **Myo-inositol (3.5 ppm):** Marker for Alzheimer’s disease and low-grade gliomas.

Question 276: Tram-like calcifications are seen in which of the following conditions?

A. Hemangioma (Correct Answer)
B. Neurofibromatosis
C. Fibrous dysplasia
D. All of the above

Explanation: **Explanation:** **Tram-track (or tram-like) calcifications** are a classic radiological sign characterized by parallel lines of mineralization. In the context of neuroradiology and bone pathology, this finding is most characteristic of **Hemangiomas**, particularly those involving the skull or vertebral bodies. 1. **Why Hemangioma is correct:** Intraosseous hemangiomas (slow-growing vascular malformations) often present with thickened bony trabeculae. In the skull, this creates a "sunburst" or "honeycomb" appearance. However, when vascular channels within or associated with the lesion calcify (often seen in the cortical vessels or Sturge-Weber Syndrome associated leptomeningeal angiomas), they appear as **parallel linear calcifications** resembling tram tracks. 2. **Why the other options are incorrect:** * **Neurofibromatosis (NF):** NF-1 is associated with "sphenoid wing dysplasia" or "lambdoid suture defects," but not typically tram-track calcifications. * **Fibrous Dysplasia:** This condition typically presents with a **"ground-glass" appearance** on CT due to the replacement of normal bone with fibrous tissue and immature bone, rather than linear calcifications. **High-Yield Clinical Pearls for NEET-PG:** * **Sturge-Weber Syndrome:** This is the most common association for "Tram-track" intracranial calcifications. These are actually **gyriform calcifications** occurring in the cerebral cortex (layers II and III) underlying a leptomeningeal angioma. * **Vertebral Hemangioma:** On X-ray/CT, these show a **"Jail-bar"** or **"Corduroy cloth"** appearance due to thickened vertical trabeculae. * **Other "Tram-track" signs in Radiology:** * **Orbits:** Optic nerve sheath meningioma. * **Chest:** Bronchiectasis (due to thickened, non-tapering bronchial walls). * **Kidney:** Membranoproliferative Glomerulonephritis (MPGN) on basement membrane staining.

Question 277: What is the most common tumor of the head that undergoes calcification?

A. Ependymoma
B. Medulloblastoma
C. Oligodendroglioma (Correct Answer)
D. Glioblastoma multiforme

Explanation: ### Explanation **Oligodendroglioma** is the correct answer because it is the most common primary intracranial tumor to exhibit calcification. In neuroradiology, the "rule of 90s" for oligodendrogliomas states that approximately 90% of these tumors are located supratentorially (frontal lobe being the most common site) and **70–90% show calcification** on CT scans. The calcification is typically chunky, nodular, or ribbon-like and is a hallmark diagnostic feature. **Analysis of Incorrect Options:** * **Ependymoma:** While these frequently calcify (about 50% of cases), they are less common overall than oligodendrogliomas. In children, they typically arise in the fourth ventricle and show "plastic" growth through the foramina of Luschka and Magendie. * **Medulloblastoma:** These are common pediatric posterior fossa tumors, but calcification is relatively uncommon (only about 10–20% of cases). They typically appear hyperdense on non-contrast CT due to high cellularity. * **Glioblastoma Multiforme (GBM):** This is the most common primary malignant brain tumor in adults, but calcification is rare (less than 5%). If calcification is seen in a GBM, it often suggests the tumor evolved from a lower-grade precursor like an oligodendroglioma. **High-Yield Clinical Pearls for NEET-PG:** * **Most common calcified tumor in children:** Craniopharyngioma (90% calcify). * **Most common calcified intra-axial tumor in adults:** Oligodendroglioma. * **Genetic Marker:** 1p/19q co-deletion is diagnostic for oligodendroglioma and predicts a better response to chemotherapy. * **Imaging Sign:** "Fried egg appearance" on histology and "cortical expansion" on MRI.

Question 278: Intracranial calcifications on skull X-ray can include which of the following?

A. Pineal calcification
B. Dural calcification
C. Cysticercosis
D. All of these (Correct Answer)

Explanation: Intracranial calcifications are a high-yield topic in neuroradiology, as they can be either physiological (age-related) or pathological (infectious, neoplastic, or metabolic). **Explanation of the Correct Answer:** The correct answer is **D (All of these)** because intracranial calcifications are broadly categorized into: 1. **Physiological Calcifications:** These occur with aging and are usually asymptomatic. The **Pineal gland** is the most common site (seen in ~50-70% of adults). Other sites include the habenular commissure, choroid plexus, and **Dural calcifications** (such as the falx cerebri or tentorium cerebelli). 2. **Pathological Calcifications:** These result from disease processes. **Cysticercosis** (Neurocysticercosis) is a classic example where dead larvae (cysticerci) undergo granulomatous changes and eventually calcify, appearing as "rice-grain" or punctate calcifications on imaging. **Breakdown of Options:** * **Pineal calcification:** Highly common; if seen in children under 6 years, it may suggest a pineal tumor (Pineoblastoma). * **Dural calcification:** Often seen in the elderly along the falx cerebri. Extensive dural calcification can sometimes be associated with Gorlin syndrome. * **Cysticercosis:** The most common cause of acquired epilepsy in developing countries; calcified stages represent the inactive phase of the disease. **High-Yield Clinical Pearls for NEET-PG:** * **Most common physiological calcification:** Pineal gland. * **Choroid plexus calcification:** Usually seen in the atrium of the lateral ventricles. * **Basal Ganglia calcification:** If found in young patients, suspect **Fahr’s Disease** or hypoparathyroidism. * **Sturge-Weber Syndrome:** Characterized by "tram-track" or "gyriform" cortical calcifications. * **Cytomegalovirus (CMV):** Causes **periventricular** calcifications in neonates (vs. Toxoplasmosis, which causes scattered/diffuse calcifications).

Question 279: A 16-year-old boy complains of headaches for the past 9 months with no prior medical problems. Physical examination reveals no abnormal findings. A CT scan of the head shows enlargement of the lateral cerebral ventricles and third ventricle. Lumbar puncture with normal opening pressure yields clear CSF with slightly elevated protein, normal glucose, and no leukocytes. Which of the following intracranial lesions is most likely to cause these findings?

A. Aqueductal stenosis
B. Cerebral abscess
C. Cryptococcal meningitis
D. Ependymoma (Correct Answer)

Explanation: ### Explanation **Correct Answer: D. Ependymoma** The clinical presentation describes **obstructive (non-communicating) hydrocephalus**. The CT findings (enlarged lateral and third ventricles) indicate an obstruction at the level of the **Aqueduct of Sylvius** or the **Fourth Ventricle**. In children and adolescents, an **Ependymoma** typically arises from the floor of the fourth ventricle. As it grows, it obstructs CSF flow, leading to upstream dilatation of the third and lateral ventricles. The CSF analysis (elevated protein, normal glucose, no cells) is consistent with a non-inflammatory neoplastic process. **Why other options are incorrect:** * **A. Aqueductal stenosis:** While this causes the same ventricular pattern, it is usually congenital and presents in infancy with macrocephaly. A 16-year-old with a 9-month history is more likely to have an acquired neoplastic obstruction. * **B. Cerebral abscess:** This would typically present with acute/subacute fever, focal neurological deficits, and ring-enhancing lesions on CT, rather than isolated symmetrical hydrocephalus. * **C. Cryptococcal meningitis:** This causes **communicating hydrocephalus** (all ventricles, including the fourth, would be dilated) and would show low glucose and positive India ink/CrAg on CSF analysis. **NEET-PG High-Yield Pearls:** * **Ependymoma Location:** "70% occur in the posterior fossa (4th ventricle) in children; in adults, they are more common in the spinal cord." * **Radiology Sign:** On MRI, ependymomas are known as "plastic tumors" because they tend to squeeze through the Foramina of Luschka and Magendie. * **Hydrocephalus Pattern:** Obstruction at the 4th ventricle = Dilated Lateral + 3rd ventricles; Obstruction at Foramen of Monro = Dilated unilateral Lateral ventricle. * **CSF Protein:** Elevated protein in the absence of cells in a brain tumor case is often due to the "trapped" nature of the fluid or protein secretion by the tumor.

Question 280: What is the investigation of choice for laryngeal cartilage involvement?

A. CT
B. MRI (Correct Answer)
C. Radionuclide scan
D. X-ray

Explanation: **Explanation:** The assessment of laryngeal cartilage invasion is a critical step in the staging of laryngeal carcinoma (T3 vs. T4a), as it determines whether a patient can undergo organ-preserving therapy or requires a total laryngectomy. **Why MRI is the Correct Answer:** MRI is the investigation of choice because of its **superior soft-tissue contrast resolution**. It is highly sensitive (approaching 90-95%) in detecting early neoplastic infiltration of the bone marrow within the cartilage. On MRI, the replacement of the high-signal intensity fatty marrow (on T1-weighted images) by low-signal tumor tissue is a hallmark of invasion. MRI is particularly superior to CT in identifying invasion of the **non-ossified hyaline cartilage** (cricoid and thyroid cartilages). **Why Other Options are Incorrect:** * **CT:** While CT is excellent for evaluating the laryngeal skeleton and is often the first-line modality due to speed and lower cost, it has lower sensitivity for early cartilage invasion. It primarily relies on seeing "sclerosis" or "frank destruction," which may miss subtle marrow involvement. * **Radionuclide Scan:** Bone scans (Technetium-99m) are non-specific and lack the anatomical resolution required to distinguish between perichondritis (inflammation) and true tumor invasion. * **X-ray:** Plain films (like the lateral neck view) are obsolete for staging as they cannot visualize the cross-sectional extent of the tumor or subtle cortical erosions. **High-Yield Clinical Pearls for NEET-PG:** * **High Negative Predictive Value (NPV):** MRI's greatest strength is its NPV. If the MRI shows no signal change in the cartilage, invasion can be ruled out with near 100% certainty. * **Overestimation:** MRI tends to overstage (high sensitivity, lower specificity) because inflammatory edema can mimic tumor signal. * **Modality of Choice for Larynx:** For general staging and lymph nodes, **Contrast-Enhanced CT (CECT)** is often the initial study, but for **cartilage invasion**, **MRI** is the gold standard.

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