Neuroradiology Practice Questions

Q: Which of the following conditions can cause a "bare orbit"?

Metastasis. The **"Bare Orbit" sign** is a classic radiological finding on a frontal skull X-ray or CT scan characterized by the **absence of the innominate line** (the greater wing of the sphenoid bone). This occurs due to the destruction or hypoplasia of the sphenoid wing, leading to an empty-appearing orbit. ### Why Metastasis is Correct **Metastasis** (particularly from neuroblastoma in children or lung/breast cancer in adults) is a common cause of aggressive bony destruction. When the greater wing of the sphenoid is destroyed by a neoplastic process, the normal bony landmarks disappear, resulting in the "bare orbit" appearance. ### Why Other Options are Incorrect * **Pseudotumor cerebri:** This involves idiopathic intracranial hypertension. While it may cause an empty sella or slit-like ventricles, it does not cause bony destruction of the sphenoid wing. * **Optic nerve glioma:** This typically causes **enlargement of the optic canal** rather than generalized destruction of the sphenoid wing. * **Osteomyelitis:** While it can cause bone erosion, it is a rare cause of a classic "bare orbit" compared to neoplastic or congenital conditions. ### High-Yield Pearls for NEET-PG * **Most Common Cause:** The most classic association for "bare orbit" in radiology exams is **Neurofibromatosis Type 1 (NF1)**, due to congenital sphenoid wing dysplasia. * **Differential Diagnosis for Bare Orbit:** 1. Neurofibromatosis Type 1 (Sphenoid dysplasia) 2. Langerhans Cell Histiocytosis (LCH) 3. Metastatic disease (Neuroblastoma) 4. Post-surgical changes (Craniotomy) * **Clinical Correlation:** In NF1, this finding is often associated with **pulsatile exophthalmos** because the brain pulsations are transmitted directly to the orbit through the bony defect.

Q: An elderly patient presented with sudden onset of headache and altered sensorium and is diagnosed to have Subarachnoid hemorrhage. What is the best investigation of choice in this case?

CT Scan. **Explanation:** The investigation of choice for an acute **Subarachnoid Hemorrhage (SAH)** is a **Non-Contrast Computed Tomography (NCCT) scan of the head**. **1. Why CT Scan is the Correct Answer:** * **Sensitivity:** NCCT is highly sensitive (up to 98-100%) in detecting acute blood within the first 6–24 hours of the event. * **Appearance:** Acute blood appears **hyperdense (white)** on CT, typically seen filling the basal cisterns, sulci, and the Sylvian fissure (often described as a "star-shaped" density). * **Speed and Accessibility:** It is fast, widely available, and superior at detecting acute bony injuries or calcifications compared to MRI. **2. Why Other Options are Incorrect:** * **B. MRI Scan:** While MRI (especially FLAIR sequences) is sensitive, it is time-consuming, less accessible in emergencies, and difficult to perform on unstable patients with altered sensorium. It is, however, more sensitive than CT for detecting *subacute* or *chronic* SAH. * **C. Roentgenogram (X-ray) of Skull:** X-rays cannot visualize intracranial soft tissues or hemorrhages. They are obsolete for diagnosing SAH. * **D. Carotid Angiogram:** While Digital Subtraction Angiography (DSA) is the **Gold Standard** for identifying the *source* of the bleed (e.g., a ruptured berry aneurysm), it is not the initial investigation to *diagnose* the presence of hemorrhage. **Clinical Pearls for NEET-PG:** * **Initial Step:** NCCT Head. * **Next Step if NCCT is negative but clinical suspicion is high:** Lumbar Puncture (to look for **Xanthochromia**). * **Gold Standard for etiology:** Digital Subtraction Angiography (DSA). * **Commonest Cause:** Trauma (Overall); Rupture of Saccular/Berry Aneurysm (Spontaneous). * **Classic Presentation:** "Thunderclap headache" or "Worst headache of my life."

Q: 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?

Meningioma. **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.

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

Agenesis of corpus callosum. ### 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.

Q: 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?

Surgical excision. **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.

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

Meningioma. **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.

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

Oligodendroglioma. ### 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.

Q: 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?

Ependymoma. ### 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.

Q: What is the investigation of choice for an acoustic neuroma measuring 1 cm in diameter?

MRI Scan. **Explanation:** **Acoustic Neuroma (Vestibular Schwannoma)** is a benign tumor arising from the Schwann cells of the 8th cranial nerve. For any suspected retrocochlear pathology, **MRI Scan** is the gold standard and investigation of choice. 1. **Why MRI is Correct:** MRI provides superior soft-tissue contrast, allowing for the visualization of the internal auditory canal (IAC) and the cerebellopontine (CP) angle. Specifically, **Gadolinium-enhanced T1-weighted sequences** are highly sensitive, capable of detecting even tiny intracanalicular tumors (less than 5 mm). T2-weighted sequences (like FIESTA or CISS) are also excellent for visualizing the nerve complex within the CSF. 2. **Why other options are incorrect:** * **CT Scan:** While CT can show widening of the internal auditory canal or bone erosion in large tumors, it lacks the resolution to detect small (1 cm) tumors and is prone to "bone hardening" artifacts in the posterior fossa. * **Plain X-ray:** This is an obsolete method. It can only show gross bony changes in very advanced cases and cannot visualize the tumor itself. * **Air Encephalography:** This is a historical, invasive technique where air was injected into the subarachnoid space. It has been entirely replaced by non-invasive cross-sectional imaging. **High-Yield Clinical Pearls for NEET-PG:** * **Most common symptom:** Progressive unilateral sensorineural hearing loss (SNHL). * **Bilateral Acoustic Neuromas:** Pathognomonic for **Neurofibromatosis Type 2 (NF2)**. * **Radiological Sign:** The "Ice-cream cone" appearance (where the "cone" is the intracanalicular component and the "scoop" is the CP angle component). * **Gold Standard:** Gadolinium-enhanced MRI.

Question 1

Which of the following conditions can cause a "bare orbit"?

Accepted Answer

Metastasis

Answer

Pseudotumor cerebri

Answer

Optic nerve glioma

Answer

Osteomyelitis

Question 2

An elderly patient presented with sudden onset of headache and altered sensorium and is diagnosed to have Subarachnoid hemorrhage. What is the best investigation of choice in this case?

Accepted Answer

CT Scan

Answer

MRI Scan

Answer

Roentgenogram of Skull

Answer

Carotid Angiogram

Question 3

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?

Accepted Answer

Meningioma

Answer

Schwannoma

Answer

Astrocytoma

Answer

Cavernous sinus hemangioma

Question 4

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

Accepted Answer

Agenesis of corpus callosum

Answer

Lipoma of corpus callosum

Answer

Necrosis of corpus callosum

Answer

Degeneration of corpus callosum

Question 5

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?

Accepted Answer

Surgical excision

Answer

Chemotherapy with Adriamycin

Answer

Cerebral angiography with tumor embolization

Answer

Preoperative radiation therapy followed by surgical excision

Question 6

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

Accepted Answer

Meningioma

Answer

Tuberculoma

Answer

Tumors

Answer

Canavan disease

Question 7

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

Accepted Answer

Oligodendroglioma

Answer

Ependymoma

Answer

Medulloblastoma

Answer

Glioblastoma multiforme

Question 8

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?

Accepted Answer

Ependymoma

Answer

Aqueductal stenosis

Answer

Cerebral abscess

Answer

Cryptococcal meningitis

Question 9

What is the investigation of choice for laryngeal cartilage involvement?

Accepted Answer

MRI

Answer

CT

Answer

Radionuclide scan

Answer

X-ray

Question 10

What is the investigation of choice for an acoustic neuroma measuring 1 cm in diameter?

Accepted Answer

MRI Scan

Answer

CT Scan

Answer

Plain X-ray skull

Answer

Air encephalography

Neuroradiology — MCQs

Neuroradiology — MCQs

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