Neuroimaging: ADC and infarct age: 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: ADC and infarct age

Sample item

On MRI of a patient with stroke, DWI is bright and the ADC map is dark in the right MCA territory, and FLAIR is normal. How would you interpret this?

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

The answer and the reasoning

C. Hyperacute infarct within about 4.5 hours of onset (DWI-FLAIR mismatch)

Restricted diffusion with a low ADC indicates true cytotoxic oedema, and absent FLAIR change suggests early onset, within about 4.5 hours, so a DWI-FLAIR mismatch helps to select patients with unknown onset time for thrombolysis. A chronic infarct has an elevated ADC. T2 shine-through has a bright ADC.

Option by option

  • A. T2 shine-through of old gliosis

    T2 shine-through is bright on DWI but the ADC is high, not dark.

  • B. Vasogenic oedema from a tumour

    Vasogenic oedema has a high ADC.

  • C. Hyperacute infarct within about 4.5 hours of onset (DWI-FLAIR mismatch) (correct)

    Correct. Low ADC with a normal FLAIR indicates a hyperacute infarct.

  • D. Chronic infarct

    A chronic infarct has a high ADC and bright FLAIR.

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, Hyperacute infarct within about 4.5 hours of onset (DWI-FLAIR mismatch). Restricted diffusion with a low ADC indicates true cytotoxic oedema, and absent FLAIR change suggests early onset, within about 4.

Why is "T2 shine-through of old gliosis" not the answer?

T2 shine-through is bright on DWI but the ADC is high, not dark.

Why is "Vasogenic oedema from a tumour" not the answer?

Vasogenic oedema has a high ADC.

Why is "Chronic infarct" not the answer?

A chronic infarct has a high ADC and bright FLAIR.

What concept does this question test?

It tests Neuroimaging: ADC and infarct age in Radiology. 5 hours, so a DWI-FLAIR mismatch helps to select patients with unknown onset time for thrombolysis. A chronic infarct has an elevated ADC. T2 shine-through has a bright ADC.

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: ADC and infarct age?

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.