NEET-PG 2015 - Radiology Practice Questions

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: Investigation of choice for acute intracerebral hemorrhage is -

NCCT. ***NCCT*** - **Non-contrast Computed Tomography (NCCT)** is the investigation of choice for acute intracerebral hemorrhage because it can **rapidly and reliably detect acute blood** within the brain parenchyma. - Acute hemorrhage appears as a **hyperdense (bright) lesion** on NCCT, allowing for quick diagnosis and management vital in emergency settings. *MRI* - While MRI can detect hemorrhage, its sensitivity for **acute hemorrhage** can be variable, and it is **less readily available** and takes longer to perform than NCCT. - MRI is generally preferred for subacute or chronic hemorrhage, or to investigate the **underlying cause** of the bleed (e.g., tumor, vascular malformation). *PET scan* - **Positron Emission Tomography (PET) scan** primarily measures **metabolic activity** and blood flow within the brain. - It is **not suitable for detecting acute bleeding** and is typically used for diagnosing conditions like tumors, epilepsy, or neurodegenerative diseases. *None of the options* - This option is incorrect because **NCCT** is indeed the gold standard for diagnosing acute intracerebral hemorrhage.

Q: Epidural hematoma on CT scan shows which of the following?

Biconvex hyperdense lesion. ***Biconvex hyperdense lesion*** - An epidural hematoma is characterized by a **biconvex** (lens-shaped) collection of blood between the dura mater and the skull. - Since it is an acute hemorrhage, the blood appears **hyperdense** (bright white) on a CT scan. *Crescent-shaped hyperdense lesion* - A **crescent shape** is characteristic of an **acute subdural hematoma**, not an epidural hematoma. - While acute subdural hematomas are also hyperdense, their crescent shape (following the contour of the brain) distinguishes them from the biconvex epidural hematomas. - Epidural hematomas are limited by suture lines and appear lens-shaped, while subdural hematomas can cross suture lines. *Biconcave hypodense lesion* - A **biconcave** shape is not a standard description in neuroradiology and does not represent epidural hematoma. - **Hypodense** would indicate an older lesion or other pathology, not acute hemorrhage. *Ring-enhancing hypodense lesion* - **Ring-enhancing lesions** are typically associated with abscesses, glioblastoma, or metastatic tumors, not an acute hematoma. - A **hypodense** (darker) center with enhancement would indicate an abscess or necrotic tumor, not a fresh extravasation of blood.

Q: In which of the following conditions is Stereotactic Radiosurgery primarily indicated?

Arteriovenous malformation of the brain. ***Arteriovenous malformation of the brain*** - **Stereotactic Radiosurgery (SRS)** is a highly effective treatment for brain AVMs, particularly those that are **small to medium-sized** and located in eloquent brain regions. - SRS delivers a **highly focused dose of radiation** directly to the AVM, causing the abnormal blood vessels to gradually close off over time, reducing the risk of hemorrhage. *Medulloblastoma of the spinal cord* - Medulloblastoma is a **highly aggressive malignant brain tumor** that often metastasizes to the spinal cord via cerebrospinal fluid. - Treatment for spinal medulloblastoma typically involves **cranio-spinal irradiation with chemotherapy**, and SRS is generally not the primary treatment modality for diffuse spinal disease. *Ependymoma* - Ependymomas are tumors arising from the **ependymal cells** lining the ventricles and spinal cord. - While surgery is the primary treatment, radiotherapy, including **conventional fractionated external beam radiation**, is often used as adjuvant therapy, but SRS is less commonly the sole primary indication. *Glioblastoma multiforme* - Glioblastoma multiforme (GBM) is the **most aggressive primary brain tumor** and is typically treated with **maximal surgical resection followed by concurrent chemoradiotherapy**. - While SRS may be used in carefully selected cases for **recurrent GBM** or as a boost in primary treatment, it is not the primary solitary indication for initial management.

Q: Which common tracer in PET is usually administered in the form of a glucose sugar?

Fluorine 18. ***Fluorine 18*** - **18F-FDG** (Fluorodeoxyglucose) is the most common PET tracer, utilizing **Fluorine-18** as its radioactive component. - FDG is a glucose analog, meaning it mimics glucose and is taken up by metabolically active cells, allowing for imaging of **glucose metabolism**. *Aluminum - 12* - **Aluminum-12** is not a common radionuclide used in PET imaging. - The most common tracers in PET are **positron emitters** like Fluorine-18, Carbon-11, Nitrogen-13, and Oxygen-15. *Carbon 11* - **Carbon-11** can be used in PET tracers (e.g., 11C-methionine), but it is **less common** than 18F-FDG due to its shorter half-life. - Its short half-life (20 minutes) requires an **on-site cyclotron** for production, limiting its widespread use. *Oxygen 15* - **Oxygen-15** is employed in PET tracers (e.g., 15O-water for cerebral blood flow), but it has an **even shorter half-life** (2 minutes) than Carbon-11. - Its extremely short half-life makes it **impractical** for routine clinical use in the form of a glucose sugar.

Question 1

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

Accepted Answer

CT scan

Answer

MRI

Answer

PET

Answer

SPECT

Question 2

Investigation of choice for acute intracerebral hemorrhage is -

Accepted Answer

NCCT

Answer

MRI

Answer

PET scan

Answer

None of the options

Question 3

Epidural hematoma on CT scan shows which of the following?

Accepted Answer

Biconvex hyperdense lesion

Answer

Crescent-shaped hyperdense lesion

Answer

Biconcave hypodense lesion

Answer

Ring-enhancing hypodense lesion

Question 4

In which of the following conditions is Stereotactic Radiosurgery primarily indicated?

Accepted Answer

Arteriovenous malformation of the brain

Answer

Ependymoma

Answer

Medulloblastoma of the spinal cord

Answer

Glioblastoma multiforme

Question 5

Which common tracer in PET is usually administered in the form of a glucose sugar?

Accepted Answer

Fluorine 18

Answer

Aluminum - 12

Answer

Carbon 11

Answer

Oxygen 15

NEET-PG 2015 — Radiology