MRI: diffusion weighted imaging: 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 · MRI: diffusion weighted imaging

Sample item

A patient with sudden hemiparesis has a normal CT at 2 hours. Which MRI sequence would show the infarct earliest?

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

The answer and the reasoning

B. Diffusion weighted imaging with low ADC

In acute ischaemia, cytotoxic oedema restricts water movement, giving a bright DWI signal and a low ADC within minutes. Conventional T2 changes appear much later. DWI is the most sensitive test for hyperacute infarction.

Option by option

  • A. T1 with contrast

    T1 contrast enhancement appears days later.

  • B. Diffusion weighted imaging with low ADC (correct)

    Correct. DWI with low ADC detects hyperacute infarcts within minutes.

  • C. Gradient echo

    Gradient echo is used to detect haemorrhage.

  • D. T2 weighted imaging at 24 hours

    T2 changes are delayed by several hours.

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 B, Diffusion weighted imaging with low ADC. In acute ischaemia, cytotoxic oedema restricts water movement, giving a bright DWI signal and a low ADC within minutes.

Why is "T1 with contrast" not the answer?

T1 contrast enhancement appears days later.

Why is "Gradient echo" not the answer?

Gradient echo is used to detect haemorrhage.

Why is "T2 weighted imaging at 24 hours" not the answer?

T2 changes are delayed by several hours.

What concept does this question test?

It tests MRI: diffusion weighted imaging in Radiology. Conventional T2 changes appear much later. DWI is the most sensitive test for hyperacute infarction.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. 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 MRI: diffusion weighted imaging?

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.