Neuroradiology Practice Questions

Q: A 58-year-old presents with progressive cognitive decline. MRI brain is unremarkable. FDG-PET shows bilateral temporoparietal and posterior cingulate hypometabolism with relative sparing of sensorimotor cortex. Analyze these findings to determine the most likely diagnosis.

Alzheimer's disease. ***Alzheimer's disease*** - The classic FDG-PET findings for this condition involve bilateral **temporoparietal** and **posterior cingulate** hypometabolism while typically sparing the **sensorimotor cortex**. - This metabolic signature often appears during the **prodromal phase**, frequently preceding the structural **atrophy** seen on traditional MRI scans. *Normal pressure hydrocephalus* - On imaging, this condition is characterized by **ventriculomegaly** disproportionate to the degree of cortical atrophy, which is not described here. - Clinically, it presents with the classic triad of **gait disturbance**, **urinary incontinence**, and **dementia**, rather than isolated metabolic patterns on PET. *Frontotemporal dementia* - FDG-PET would typically demonstrate hypometabolism localized to the **frontal** and **anterior temporal lobes**, which differs from the posterior pattern seen in this case. - Early symptoms usually include significant **personality changes** or **behavioral disturbances** rather than generalized progressive cognitive decline alone. *Vascular dementia* - PET scanning usually shows a **focal or multifocal** "patchy" pattern of hypometabolism corresponding to areas of prior **infarction** or chronic ischemia. - Diagnosis is generally supported by MRI evidence of **lacunar infarcts**, **extensive white matter disease**, or territorial strokes.

Q: Which imaging modality is best for evaluating retinoblastoma?

CT scan and MRI. **Explanation:** Retinoblastoma is the most common primary intraocular malignancy in children. The diagnosis and staging require a multi-modal imaging approach, making **CT scan and MRI** the combined gold standard. * **Why CT and MRI are both essential:** * **CT Scan:** It is the most sensitive modality for detecting **intraocular calcification**, which is the hallmark of retinoblastoma (seen in >90% of cases). CT is crucial for confirming the diagnosis when clinical findings are ambiguous. * **MRI:** It is the modality of choice for **staging**. MRI provides superior soft-tissue contrast to evaluate for optic nerve invasion, extraocular extension, and intracranial involvement (such as trilateral retinoblastoma involving the pineal gland). Crucially, MRI avoids ionizing radiation, which is vital in these patients who often have a genetic predisposition to secondary malignancies (RB1 mutation). **Analysis of Incorrect Options:** * **A. Ultrasonography:** While useful for initial screening and detecting calcified masses (showing high reflectivity with acoustic shadowing), it is operator-dependent and cannot assess posterior extension or intracranial spread. * **B & D. CT or MRI alone:** While both are powerful, neither is sufficient on its own for a complete evaluation. CT excels at identifying pathognomonic calcification, while MRI is mandatory for assessing the extent of the disease and planning management. **High-Yield Clinical Pearls for NEET-PG:** * **Classic Presentation:** Leukocoria (white pupillary reflex) in a child under 3 years. * **Trilateral Retinoblastoma:** Bilateral retinoblastoma associated with a pineal gland tumor (Pineoblastoma). * **Imaging Sign:** "Cloud-like" or "clumpy" calcification on CT. * **Management Tip:** Avoid biopsy (fine-needle aspiration) due to the high risk of tumor seeding along the needle track. Diagnosis is based on clinical exam and imaging.

Q: Intra-tumoral calcification in the brain is seen in all except?

Hemangioblastoma. **Explanation:** The correct answer is **Hemangioblastoma**. In neuroradiology, identifying the presence or absence of calcification is a high-yield diagnostic marker for intracranial tumors. **1. Why Hemangioblastoma is the correct answer:** Hemangioblastomas are highly vascular, WHO Grade 1 tumors typically located in the posterior fossa (cerebellum). Characteristically, they present as a **cystic lesion with a highly enhancing mural nodule**. Crucially, hemangioblastomas **do not calcify**. Their primary imaging features are related to vascularity (flow voids on MRI) and associated erythropoietin production, which may lead to polycythemia. **2. Why the other options are incorrect:** * **Oligodendroglioma:** This is the "classic" answer for calcified brain tumors. Calcification is seen in **70–90%** of cases, often described as chunky or ribbon-like. * **Craniopharyngioma:** In the pediatric population (adamantinomatous type), calcification is a hallmark, occurring in approximately **90%** of cases. It follows the "90% rule": 90% are cystic, 90% calcify, and 90% enhance. * **Meningioma:** These are extra-axial tumors that frequently show calcification (about **20–25%**). When the calcification is diffuse and gritty, they are histologically termed "Psammomatous meningiomas." **NEET-PG High-Yield Pearls:** * **Mnemonic for Calcified Brain Tumors (Old Men Are Posh):** **O**ligodendroglioma, **M**eningioma, **A**strocytoma, **P**ineal tumors/ **P**apilloma (Choroid plexus). * **Most common calcified tumor in children:** Craniopharyngioma. * **Most common calcified tumor in adults:** Oligodendroglioma. * **Hemangioblastoma Association:** Frequently associated with **Von Hippel-Lindau (VHL) syndrome**; look for retinal angiomas and renal cell carcinoma in clinical stems.

Q: Which of the following brain tumors is typically hyperdense on CT scan?

Medulloblastoma. **Explanation:** The density of a tumor on a non-contrast CT (NCCT) scan is primarily determined by its **cellularity** and the **nuclear-to-cytoplasmic (N:C) ratio**. **1. Why Medulloblastoma is correct:** Medulloblastoma is a "Small Round Blue Cell Tumor." These tumors are characterized by extremely high cellular density and very little cytoplasm. Because DNA and cellular proteins attenuate X-rays more than water or lipids, the high concentration of cells makes the tumor appear **hyperdense** relative to the normal brain parenchyma on NCCT. This is a classic radiological hallmark of medulloblastoma, typically seen in the midline (cerebellar vermis) of pediatric patients. **2. Analysis of Incorrect Options:** * **Ependymoma:** Usually appears isodense or heterogeneous on CT. While they often contain calcifications (which are hyperdense), the soft tissue component itself is not typically hyperdense. * **Oligodendroglioma:** These are known for having the highest incidence of **calcification** (up to 90%), which is hyperdense. However, the tumor mass itself is usually hypo-to-isodense. * **Astrocytoma:** Most low-grade astrocytomas are **hypodense** due to high water content and associated edema. High-grade gliomas (GBM) are usually heterogeneous due to necrosis and hemorrhage. **3. High-Yield Clinical Pearls for NEET-PG:** * **Hyperdense tumors on CT (Mnemonic: "M-L-G"):** **M**edulloblastoma, **L**ymphoma (Primary CNS), and **G**erm cell tumors/Meningioma. * **Medulloblastoma:** Most common malignant brain tumor in children; associated with "drop metastases" (seeding via CSF). * **Calcification Mnemonic:** "Old Elephants Can't Dance" (**O**ligodendroglioma, **E**pendymoma, **C**raniopharyngioma, **D**ysembryoplastic Neuroepithelial Tumor).

Question 1

A 58-year-old presents with progressive cognitive decline. MRI brain is unremarkable. FDG-PET shows bilateral temporoparietal and posterior cingulate hypometabolism with relative sparing of sensorimotor cortex. Analyze these findings to determine the most likely diagnosis.

Accepted Answer

Alzheimer's disease

Answer

Normal pressure hydrocephalus

Answer

Frontotemporal dementia

Answer

Vascular dementia

Question 2

How does diffusion-weighted imaging (DWI) detect acute stroke earlier than conventional MRI sequences?

Accepted Answer

By measuring restricted water diffusion due to cytotoxic edema

Answer

By detecting increased blood flow to ischemic tissue

Answer

By identifying hemorrhagic transformation

Answer

By detecting breakdown of blood-brain barrier

Question 3

Which imaging modality is best for evaluating retinoblastoma?

Accepted Answer

CT scan and MRI

Answer

Ultrasonography

Answer

CT scan

Answer

MRI

Question 4

Intra-tumoral calcification in the brain is seen in all except?

Accepted Answer

Hemangioblastoma

Answer

Craniopharyngioma

Answer

Meningioma

Answer

Oligodendroglioma

Question 5

Which of the following brain tumors is typically hyperdense on CT scan?

Accepted Answer

Medulloblastoma

Answer

Ependymoma

Answer

Oligodendroglioma

Answer

Astrocytoma

Neuroradiology — MCQs

Neuroradiology — MCQs

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