Neuroradiology - 1 - Free MCQ Practice Test with solutions, NEET PG

The appearance of a puff of smoke on cerebral angiography is linked to:

• Moyamoya disease: This condition causes narrowing of the blood vessels in the brain, leading to the formation of small, fragile vessels that resemble a "puff of smoke" on imaging.

To tell the difference between an epidermoid cyst and an arachnoid cyst, the following points are important:

• Contrast enhancement: This is often used in imaging to see how different tissues absorb contrast material.
• Restricted diffusion: This refers to the ability of water molecules to move freely in tissue. In imaging, restricted diffusion helps distinguish types of cysts.
• CSF signals on FLAIR: Fluid-attenuated inversion recovery (FLAIR) imaging helps identify the characteristics of cerebrospinal fluid (CSF) in the cysts.
• Smooth margin: The edges of the cysts can provide clues; smooth margins are often seen in different types of cysts.

Among these, restricted diffusion is a key factor that helps differentiate the two types of cysts effectively.

The most effective investigation for diagnosing lepto-meningeal carcinomatosis is:

• Gadolinium-enhanced MRI: This imaging technique is particularly useful because it provides detailed images of the brain and spinal cord, helping to identify any cancer spread.
• Other methods, like PET and SPECT, may not be as effective in detecting this specific condition.
• CT scans can be helpful but are less sensitive than MRI for this purpose.

In summary, Gadolinium-enhanced MRI is the preferred choice for accurately diagnosing lepto-meningeal carcinomatosis.

The symptoms presented include:

• Weakness in the lower limbs that is gradually getting worse.
• Spasticity, which means increased muscle tightness.
• Hesitancy when urinating, which has started recently.

During a neurological examination, signs of dorsal myelopathy were observed. An MRI scan of the spine showed a mid dorsal mass that enhances with contrast, indicating it is likely a mass located within the dura mater (the protective covering of the spinal cord).

Given these findings, the most likely diagnosis is a meningioma, which is a type of tumour that arises from the meninges. Meningiomas can cause symptoms due to their location and pressure on nearby structures.

The characteristic MRI finding for an intra-cranial cavernous angioma is:

• Reticulated ‘popcorn-like configuration’.
• This appearance is due to the presence of multiple small vascular channels.
• It is important to note that other features like well-defined nidus or arterial feeders are not typical for this condition.
• Recognising this configuration can aid in accurate diagnosis.

For evaluating an acute head injury, the best investigation is a Non-Contrast Computed Tomography (NCCT) scan of the head. This method is preferred because:

• It quickly identifies bleeding or fractures.
• It is readily available in most hospitals.
• It involves no use of contrast agents, making it safer for patients.
• It is effective in assessing acute injuries, providing clear images of the brain.

Other options like CECT, MRI, and PET scans are not the first choice due to factors such as longer scanning times or the need for contrast material.

The differential diagnosis for spinal cord edema on MRI includes:

• Myelodysplasia: A condition where the spinal cord develops abnormally.
• Myelomalacia: Softening of the spinal cord due to injury or lack of blood flow.
• Myeloschisis: A severe birth defect where the spinal cord is not closed completely.
• Cord tumours: Abnormal growths that can cause swelling in the spinal cord.

When neurons migrate during brain development, any disruption can lead to problems in their movement and arrangement. This can cause various brain disorders. The disorders that might occur include:

• Polymicrogyria - This condition involves an abnormal number of small folds in the brain's surface.
• Schizencephaly - This is a rare disorder characterized by abnormal clefts or slits in the brain.
• Lissencephaly - This disorder results in a smooth brain surface due to improper neuronal migration.
• Focal cortical dysplasia without balloon cells - This condition affects brain structure but does not involve specific cell types.

Among these, some disorders are more likely to be linked to neuronal migration issues than others. Understanding these conditions helps in identifying their causes and impacts.

The symptoms described suggest a condition affecting both the upper and lower motor neurons. The key points are:

• Progressive atrophy and weakness in the hands and forearms indicate muscle degeneration.
• Slight spasticity in the leg and generalized hyperreflexia suggest upper motor neuron involvement.
• Increased signal in the cortico-spinal tracts on T2-weighted MRI further supports this diagnosis.

Considering these factors, the most likely diagnosis is Amyotrophic lateral sclerosis (ALS), as it typically presents with both lower motor neuron signs (like muscle weakness) and upper motor neuron signs (like spasticity and hyperreflexia).

Raised intracranial pressure (ICP) can show certain signs on plain radiology. Here are the characteristics associated with it:

• Erosion of the dorsum sella
• Ballooning of the sella
• Increased convolutions of the brain
• Sutural diastasis

However, the one characteristic that does not indicate raised ICP is:

• Ballooning of the sella

The patient was unconscious and had visible injuries. The CT scan indicated no midline shift, but the basal cisterns were compressed and there were multiple small haemorrhages. This suggests a serious condition affecting the brain.

• Brain contusion: This is a bruise on the brain, but it usually involves swelling and not just small haemorrhages.
• Diffuse axonal injury: This is caused by severe shaking or rotational forces, often leading to widespread damage; however, the CT findings here are not typical.
• Subdural haemorrhage: This occurs when blood collects between the brain and its outer covering, which can lead to compression but is not supported by the CT findings.
• Multiple infarcts: These are areas of dead tissue due to lack of blood supply, but they do not typically cause multiple small haemorrhages in this manner.

The most likely diagnosis, based on the CT findings of small haemorrhages and compression of the basal cisterns, is diffuse axonal injury. This condition often results from traumatic brain injury and presents with such imaging characteristics.

The best non-invasive strategy to diagnose the cause of the seizures is:

• Video EEG with Ictal 99m Tc­HMPAO Brain SPECT. This method allows for continuous monitoring of brain activity during seizures and provides valuable information about the areas of the brain involved.

This approach is effective in accurately localising seizure origins, which is crucial for planning potential epilepsy surgery.

Basal exudates, infarcts, and hydrocephalus can be identified on a computed tomography (CT) scan in certain medical conditions. Here’s a brief overview:

• Tuberculous meningitis: This condition often leads to inflammation in the brain, which can be visible as basal exudates on a CT scan.
• Viral meningitis: While it may cause some changes in the brain, it typically does not present with basal exudates.
• Herpes simplex encephalitis: This serious infection can show significant brain swelling and sometimes exudates, especially in advanced cases.
• Cerebral malaria/neurocysticercosis: Both can result in significant brain changes but are less likely to show basal exudates specifically.

Among these, tuberculous meningitis is most commonly associated with basal exudates and the other complications mentioned.

A focal cerebral lesion that appears as a ring on a CT scan typically indicates the presence of certain conditions. One of the most common causes is Toxoplasmosis, which is an infection caused by a parasite. This can lead to areas in the brain that are inflamed and necrotic, resulting in a ring-like appearance.

Other potential causes include:

• Intracranial haemorrhage: Bleeding within the brain can create lesions that may appear as rings.
• Cysts: Certain cystic formations in the brain can also have a ring-like structure.
• Hamartoma: This benign tumour can sometimes present as a ring on imaging.

In summary, while there are several possible causes for a ring-like lesion, Toxoplasmosis is the most notable, especially in immunocompromised patients.

Suprasellar calcification is a specific feature found primarily in:

• Craniopharyngioma - This is a benign brain tumour that often occurs near the pituitary gland, leading to calcifications in the suprasellar region.
• Medulloblastoma - Typically found in the cerebellum, it does not usually present with suprasellar calcifications.
• Meningioma - These tumours can occur near the brain but are less associated with suprasellar calcifications.
• Ependymoma - While they can develop in the brain or spinal cord, they are not specifically linked to suprasellar calcification.

Hence, the most characteristic tumour associated with suprasellar calcification is craniopharyngioma.