CT: partial volume effect: 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.

Try it

Radiology · CT: partial volume effect

Sample item

A 4 mm hypodense nodule in the liver measures 20 HU on a 10 mm slice but its true density is close to that of water. Which step best reduces this error?

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

The answer and the reasoning

D. Reconstructing thinner slices

In partial volume averaging, a structure smaller than the slice thickness is averaged with adjacent tissue so its measured attenuation is wrong. Thinner slices reduce the volume averaged and give a truer HU value.

Option by option

  • A. Lowering the kVp

    Changing kVp alters attenuation values but does not cure averaging.

  • B. Using oral contrast

    Oral contrast does not address averaging within a slice.

  • C. Using a wider window width

    Window width changes display contrast, not the measured HU.

  • D. Reconstructing thinner slices (correct)

    Correct. Thin slices reduce averaging of the small lesion with surrounding liver.

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.

More Radiology questions

Questions about this Radiology question

What is the answer to this Radiology question?

The best answer is D, Reconstructing thinner slices. In partial volume averaging, a structure smaller than the slice thickness is averaged with adjacent tissue so its measured attenuation is wrong.

Why is "Lowering the kVp" not the answer?

Changing kVp alters attenuation values but does not cure averaging.

Why is "Using oral contrast" not the answer?

Oral contrast does not address averaging within a slice.

Why is "Using a wider window width" not the answer?

Window width changes display contrast, not the measured HU.

What concept does this question test?

It tests CT: partial volume effect in Radiology. Thinner slices reduce the volume averaged and give a truer HU value.

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 CT: partial volume effect?

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.