Neuroimaging: practice question

A Radiology question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Radiology · Neuroimaging

Sample item

A 65-year-old man has sudden right hemiparesis and aphasia for 90 minutes. A non-contrast CT head shows no haemorrhage and no obvious abnormality. Which MRI sequence will show acute infarction earliest?

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

C. Diffusion-weighted imaging with low apparent diffusion coefficient

Cytotoxic oedema in acute ischaemia restricts the movement of water molecules, producing high signal on diffusion-weighted imaging and low signal on the ADC map within minutes of onset. CT and conventional MRI sequences may remain normal for hours. Early CT is mainly used to exclude haemorrhage before thrombolysis.

Option by option

  • A. T2-weighted FLAIR imaging

    FLAIR changes appear later, typically after several hours.

  • B. T1-weighted imaging after gadolinium

    Post-gadolinium T1 enhancement appears later when the blood-brain barrier breaks down.

  • C. Diffusion-weighted imaging with low apparent diffusion coefficient (correct)

    Correct. Restricted diffusion appears within minutes of vessel occlusion.

  • D. T1-weighted imaging without contrast

    Unenhanced T1 images are insensitive for early infarcts.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

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Questions about this Radiology question

What is the answer to this Radiology question?

The best answer is C, Diffusion-weighted imaging with low apparent diffusion coefficient. Cytotoxic oedema in acute ischaemia restricts the movement of water molecules, producing high signal on diffusion-weighted imaging and low signal on the ADC map within minutes of onset.

Why is "T2-weighted FLAIR imaging" not the answer?

FLAIR changes appear later, typically after several hours.

Why is "T1-weighted imaging after gadolinium" not the answer?

Post-gadolinium T1 enhancement appears later when the blood-brain barrier breaks down.

Why is "T1-weighted imaging without contrast" not the answer?

Unenhanced T1 images are insensitive for early infarcts.

What concept does this question test?

It tests Neuroimaging in Radiology. CT and conventional MRI sequences may remain normal for hours. Early CT is mainly used to exclude haemorrhage before thrombolysis.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Neuroimaging?

Learn signs with the image, and the disease they point to. Then use the flashcards and the other Radiology questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.