Neuroradiology Practice Questions

Q: Identify the condition shown in the MRI image.

Dandy-Walker malformation. ***Dandy-Walker malformation*** - The image shows an enlarged posterior fossa with **cystic dilation of the fourth ventricle** and **absence/hypoplasia of the cerebellar vermis**, which are classic features of Dandy-Walker malformation. - The elevated tentorium is also characteristic, contributing to the distinct appearance. *Cerebellar vermis hypoplasia* - While cerebellar vermis hypoplasia is a component of Dandy-Walker malformation, it is not the sole, defining feature. - Dandy-Walker also includes cystic dilation of the fourth ventricle and an enlarged posterior fossa, which are evident in the image and go beyond isolated vermis hypoplasia. *Mega cisterna magna* - A **mega cisterna magna** is a benign enlargement of the cisterna magna, which is the space between the cerebellum and the medulla oblongata. - Unlike in Dandy-Walker malformation, a mega cisterna magna usually does not involve displacement of the tentorium or hypoplasia of the cerebellar vermis, and the fourth ventricle is typically normal in shape and size. *None of the options* - The image clearly displays the diagnostic hallmarks of Dandy-Walker malformation, making this option incorrect.

Q: Investigation of choice to evaluate intracranial hemorrhage of less than 48 hours is -

CT scan. ***CT scan*** - **Non-contrast CT** is the most sensitive and rapid imaging modality for detecting acute intracranial hemorrhage, appearing as a **hyperdense** (bright) area within the brain parenchyma or subarachnoid space. - It is readily available in emergency settings and is crucial for immediate diagnosis to guide management, especially within the first **48 hours**. *MRI* - While MRI can detect hemorrhage, its sensitivity for **acute hemorrhage** (especially within the first few hours) is less than CT, and it is more time-consuming. - MRI is superior for detecting older hemorrhage or subtle lesions, but it is not the **first-line investigation** for acute bleeding. *PET* - **Positron Emission Tomography** (PET) scans are primarily used to assess metabolic activity and blood flow in the brain, often for conditions like cancer, epilepsy, or dementia. - It does not directly visualize fresh blood and therefore is not used for the diagnosis of **acute intracranial hemorrhage**. *SPECT* - **Single-Photon Emission Computed Tomography** (SPECT) is used to evaluate cerebral blood flow and neuronal activity, similar to PET but with different tracers and resolution. - It is not indicated for the rapid assessment of **acute intracranial hemorrhage** as it does not directly image blood.

Q: Tigroid pattern on MRI is seen in -

Metachromatic leukodystrophy. ***Metachromatic leukodystrophy*** - The **tigroid pattern** on MRI, characterized by **perivascular sparing** within demyelinated white matter, is highly characteristic of metachromatic leukodystrophy. - This pattern results from the accumulation of **sulfatides** in oligodendrocytes and macrophages, leading to central demyelination with spared U-fibers and white matter adjacent to vessels. *Wilson's disease* - Wilson's disease involves **copper accumulation** and typically presents with abnormalities in the **basal ganglia**, thalami, and brainstem. - While it causes neurodegeneration, it does not produce a characteristic tigroid demyelination pattern. *Parkinsonism* - Parkinsonism refers to a group of neurological disorders characterized by motor symptoms like **bradykinesia, rigidity, tremor, and postural instability**. - MRI findings in Parkinsonism often show **nigral degeneration** but do not typically involve a tigroid pattern of leukodystrophy. *GB syndrome* - **Guillain-Barré syndrome (GBS)** is an acute autoimmune peripheral neuropathy affecting the **peripheral nerves and nerve roots**. - It does not involve central nervous system demyelination or display a tigroid pattern on brain MRI.

Q: On imaging, diffuse axonal injury is characterized by -

Multiple small petechial hemorrhages. ***Multiple small petechial hemorrhages*** - Diffuse axonal injury (DAI) is characterized on imaging by numerous **small petechial hemorrhages** at the **gray-white matter junction**, **corpus callosum**, and **brainstem**. - These microhemorrhages are the **hallmark imaging finding** and are best visualized on MRI (GRE/SWI sequences), though they can be seen on CT as small hyperdensities. - This is the **most specific** and characteristic finding that defines DAI. *Patchy ill-defined low density lesion mixed with small hyperdensities of petechial hemorrhage* - While this description can be seen in DAI (combining edema with microhemorrhages), it is **less specific** and could represent other entities. - This mixed pattern is more commonly associated with **contusions** where there is more prominent parenchymal injury with larger areas of edema and hemorrhage. - DAI classically shows predominantly **small punctate hemorrhages** rather than larger patchy low-density lesions. *Crescentic extra-axial hematoma* - A crescentic extra-axial collection describes a **subdural hematoma**, which is an entirely separate entity from DAI. - Subdural hematomas are located between the dura and arachnoid membranes, whereas DAI involves direct **axonal shearing injury** within brain parenchyma. *White matter lucencies* - This is a **non-specific finding** that can occur in many conditions including ischemia, demyelination, and chronic small vessel disease. - While DAI can cause white matter edema leading to lucencies, this does not capture the **characteristic petechial hemorrhages** that define the condition on imaging.

Q: Which imaging modality is most effective in differentiating between epidermoid cyst and arachnoid cyst?

Magnetic Resonance Imaging (MRI). ***Magnetic Resonance Imaging (MRI)*** - **MRI** is superior for differentiating epidermoid and arachnoid cysts due to its excellent **soft tissue contrast** and ability to detect fluid signal characteristics. - **Diffusion-weighted imaging (DWI)**, a specific MRI sequence, is crucial; **epidermoid cysts** show high signal on DWI (diffusion restriction) due to their keratin content, while **arachnoid cysts** follow CSF signal on all sequences and do not restrict diffusion. *Ultrasound (USG)* - **Ultrasound** has limited utility for intracranial lesions in adults due to the bony skull, which prevents sound wave penetration. - It may be used in infants through the fontanelles but lacks the resolution and specific sequences needed to characterize these cysts. *Computed Tomography (CT) scan* - While a **CT scan** can identify these cysts as hypodense lesions, it lacks the detailed **tissue characterization** and signal patterns provided by MRI. - Both cysts would appear as **hypodense lesions**, making differentiation difficult based on density alone, especially after contrast administration. *Positron Emission Tomography (PET) scan* - A **PET scan** primarily assesses metabolic activity and would not effectively differentiate between benign **non-metabolic cysts** like epidermoid and arachnoid cysts. - It is more commonly used for detecting **malignancies** or assessing brain activity patterns, not for structural differentiation of fluid-filled lesions.

Q: What is the CT scan finding in a carotid cavernous sinus fistula?

Enlarged superior ophthalmic vein. ***Enlarged superior ophthalmic vein*** * A carotid cavernous sinus fistula (CCSF) causes **high-pressure arterial blood** to shunt into the **venous system** of the cavernous sinus. * This increased pressure leads to retrograde flow and congestion in the draining veins, most notably the **superior ophthalmic vein**, causing its dilation. *Enlarged inferior ophthalmic vein* * While the inferior ophthalmic vein can also be involved in some cases of CCSF, the **superior ophthalmic vein** is typically more prominent and consistently affected due to its primary drainage pathway. * The inferior ophthalmic vein is less frequently the primary or most notable imaging finding compared to the superior ophthalmic vein. *Enlarged superior ophthalmic artery* * A CCSF involves an abnormal connection between the **carotid artery** (an artery) and the **cavernous sinus** (a venous structure), leading to venous, not arterial, dilation. * Arteries in the orbital region, like the superior ophthalmic artery, would not typically enlarge as a direct result of increased venous pressure in the cavernous sinus. *Enlarged inferior ophthalmic artery* * Similar to the superior ophthalmic artery, the inferior ophthalmic artery is an **arterial structure** and would not enlarge due to a high-flow arteriovenous shunt within the cavernous sinus. * The pathological changes in CCSF are primarily observed in the **venous drainage pathways**.

Q: Which CT view is best for visualizing paranasal polyps?

Coronal view. ***Coronal*** - The **coronal view** provides the best visualization of the **ostia of the paranasal sinuses**, which are crucial for assessing the extent and obstruction caused by polyps. - This orientation effectively demonstrates whether polyps are **protruding into the nasal cavity** or obstructing the drainage pathways. *Axial view* - The axial view is useful for evaluating **posterior structures** and **bony erosion** but is less optimal for assessing the vertical extent of polyps or ostial obstruction. - It can show the **anteroposterior dimensions** of polyps but does not offer the same clarity for sinus outflow tracts as the coronal view. *Sagittal view* - The sagittal view is good for showing the **craniocaudal extent** of lesions and differentiating between the nasal cavity and sphenoid sinus, but it is not ideal for comprehensive paranasal sinus polyp evaluation. - It can help in localizing some polyps but does not provide a clear overview of **sinus ostia** or lateral extension. *3D view* - A 3D reconstruction can be helpful for a general overview and surgical planning but does not offer the fine detail and specific orientation needed for primary polyp detection and ostial assessment as effectively as direct 2D views. - It is a derived image rather than a primary acquisition plane and might obscure smaller polyps or subtle anatomical relationships.

Q: Tear drop sign is seen in?

Blow out fracture. ***Blow out fracture*** - The **tear drop sign** on imaging (often CT scan) is characteristic of an **orbital blow-out fracture**, indicating herniation of orbital contents (fat, muscle) into the maxillary sinus. - This fracture typically involves the **orbital floor** or medial wall, often caused by a blunt force trauma to the eye. *Fracture zygomatic arch* - A fracture of the zygomatic arch is often associated with a **flattening of the malar prominence** rather than a "tear drop" sign. - It might lead to restricted jaw movement if the arch impinges on the coronoid process. *Fracture maxilla* - Maxillary fractures (e.g., Le Fort fractures) involve the midface bones and cause **facial deformity**, malocclusion, and mobility of the maxilla. - The tear drop sign is not a primary diagnostic feature of maxillary fractures. *Fracture mandible* - Mandibular fractures present with pain, swelling, and **malocclusion** of the teeth. - Imaging would reveal a break in the mandible, not a tear drop sign associated with orbital contents.

Q: A polytrauma patient's CT brain shows a crescent-shaped extra-axial collection with a concave inner margin. What is the most likely diagnosis?

SDH. ***SDH*** - The image shows a **crescent-shaped collection** of hemorrhage with a concave inner margin, consistent with a **subdural hematoma** (SDH). - SDHs result from the tearing of **bridging veins** and typically conform to the brain's surface, crossing suture lines but not limited by bony sutures. *EDH* - An **epidural hematoma (EDH)** characteristically appears as a **lenticular** or **biconvex** shape on CT, not crescent-shaped. - EDHs are typically caused by arterial bleeding, often from the **middle meningeal artery**, and are limited by cranial sutures. *Contusion* - A **contusion** is brain tissue bruising that appears as **heterogeneous areas** of hemorrhage and edema within the brain parenchyma itself. - It would not manifest as a distinct extra-axial collection with a smooth, concave margin. *Diffuse axonal injury* - **Diffuse axonal injury (DAI)** involves widespread microscopic damage to axons, often at the gray-white matter junction. - It may appear as *punctate hemorrhages* or **small lesions** at these junctions on CT, but often the CT can be normal, and it would not present as a large extra-axial collection.

Q: Investigation of choice for intramedullary SOL is -

MRI. ***MRI*** - **Magnetic Resonance Imaging (MRI)** is the investigation of choice for intramedullary lesions due to its superior **soft tissue contrast** and ability to visualize the **spinal cord** parenchyma. - It provides detailed information on lesion size, location, and internal characteristics, which is crucial for diagnosis and surgical planning. *USG* - **Ultrasound (USG)** has limited utility for intramedullary lesions as a primary diagnostic tool because **bone impedes sound waves**, making it difficult to visualize structures within the spinal canal. - It might be used for neonatal spinal screening or intraoperative guidance, but not for definitive diagnosis of intramedullary lesions in adults. *CT* - **Computed Tomography (CT)** excels at visualizing **bone structures** and calcifications, but it provides less detailed information about soft tissue elements like the spinal cord compared to MRI. - While it can identify bony changes associated with intramedullary lesions, it is not the preferred initial imaging modality for characterizing the lesion itself. *X-ray* - **X-rays** provide basic imaging of bone but offer essentially **no visualization of soft tissues** such as the spinal cord or intramedullary lesions. - They are primarily used to identify gross bony abnormalities like fractures or severe degenerative changes, not for subtle intraspinal pathologies.

Question 1

Identify the condition shown in the MRI image.

Accepted Answer

Dandy-Walker malformation

Answer

None of the options

Answer

Cerebellar vermis hypoplasia

Answer

Mega cisterna magna

Question 2

Investigation of choice to evaluate intracranial hemorrhage of less than 48 hours is -

Accepted Answer

CT scan

Answer

MRI

Answer

PET

Answer

SPECT

Question 3

Tigroid pattern on MRI is seen in -

Accepted Answer

Metachromatic leukodystrophy

Answer

Wilson's disease

Answer

Parkinsonism

Answer

GB syndrome

Question 4

On imaging, diffuse axonal injury is characterized by -

Accepted Answer

Multiple small petechial hemorrhages

Answer

Patchy ill-defined low density lesion mixed with small hyperdensities of petechial hemorrhage

Answer

Crescentic extra-axial hematoma

Answer

White matter lucencies

Question 5

Which imaging modality is most effective in differentiating between epidermoid cyst and arachnoid cyst?

Accepted Answer

Magnetic Resonance Imaging (MRI)

Answer

Ultrasound (USG)

Answer

Computed Tomography (CT) scan

Answer

Positron Emission Tomography (PET) scan

Question 6

What is the CT scan finding in a carotid cavernous sinus fistula?

Accepted Answer

Enlarged superior ophthalmic vein

Answer

Enlarged inferior ophthalmic vein

Answer

Enlarged superior ophthalmic artery

Answer

Enlarged inferior ophthalmic artery

Question 7

Which CT view is best for visualizing paranasal polyps?

Accepted Answer

Coronal view

Answer

Axial view

Answer

Sagittal view

Answer

3D view

Question 8

Tear drop sign is seen in?

Accepted Answer

Blow out fracture

Answer

Fracture zygomatic arch

Answer

Fracture maxilla

Answer

Fracture mandible

Question 9

A polytrauma patient's CT brain shows a crescent-shaped extra-axial collection with a concave inner margin. What is the most likely diagnosis?

Accepted Answer

SDH

Answer

EDH

Answer

Contusion

Answer

Diffuse axonal injury

Question 10

Investigation of choice for intramedullary SOL is -

Accepted Answer

MRI

Answer

USG

Answer

CT

Answer

X-ray

Neuroradiology — MCQs

Neuroradiology — MCQs

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