MRI: metal susceptibility artefact: 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: metal susceptibility artefact

Sample item

A patient with spinal pedicle screws needs an MRI. The images show signal loss and geometric distortion around the metal. Which choice reduces this?

AUsing gradient echo with long echo timeBUsing fast spin echo sequences rather than gradient echoCRaising the field strengthDSwitching to a larger voxel only

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

The answer and the reasoning

B. Using fast spin echo sequences rather than gradient echo

Metal distorts the local magnetic field, an effect that dephases spins and is not refocused by gradient echo. Spin echo based sequences refocus much of it, and lower field strength and short echo times help.

Option by option

A. Using gradient echo with long echo time
Gradient echo with long echo time worsens the artefact.
B. Using fast spin echo sequences rather than gradient echo (correct)
Correct. Spin echo based sequences are less sensitive to susceptibility.
C. Raising the field strength
Higher field strength increases susceptibility effects.
D. Switching to a larger voxel only
A larger voxel alone does not correct field distortion.

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.

Questions about this Radiology question

What is the answer to this Radiology question?

The best answer is B, Using fast spin echo sequences rather than gradient echo. Metal distorts the local magnetic field, an effect that dephases spins and is not refocused by gradient echo.

Why is "Using gradient echo with long echo time" not the answer?

Gradient echo with long echo time worsens the artefact.

Why is "Raising the field strength" not the answer?

Higher field strength increases susceptibility effects.

Why is "Switching to a larger voxel only" not the answer?

A larger voxel alone does not correct field distortion.

What concept does this question test?

It tests MRI: metal susceptibility artefact in Radiology. Spin echo based sequences refocus much of it, and lower field strength and short echo times help.

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: metal susceptibility artefact?

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.