Ultrasound: resistive index calculation: 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 · Ultrasound: resistive index calculation

Sample item

On spectral Doppler of a renal artery, peak systolic velocity is 80 cm/s and end-diastolic velocity is 20 cm/s. What is the resistive index?

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

The answer and the reasoning

A. 0.75

Resistive index is the peak systolic velocity minus the end-diastolic velocity, divided by the peak systolic velocity. Here (80 minus 20) divided by 80 gives 0.75, which is above the usual upper limit of about 0.70 for a normal kidney.

Option by option

  • A. 0.75 (correct)

    Correct. (80 - 20) / 80 = 0.75.

  • B. 0.60

    This does not follow from the given velocities.

  • C. 4.0

    This is the ratio of systolic to diastolic velocity, not the resistive index.

  • D. 0.25

    This is the end-diastolic velocity divided by the peak systolic velocity, which is not the index.

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 A, 0.75. Resistive index is the peak systolic velocity minus the end-diastolic velocity, divided by the peak systolic velocity.

Why is "0.60" not the answer?

This does not follow from the given velocities.

Why is "4.0" not the answer?

This is the ratio of systolic to diastolic velocity, not the resistive index.

Why is "0.25" not the answer?

This is the end-diastolic velocity divided by the peak systolic velocity, which is not the index.

What concept does this question test?

It tests Ultrasound: resistive index calculation in Radiology. Here (80 minus 20) divided by 80 gives 0.75, which is above the usual upper limit of about 0.70 for a normal kidney.

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 Ultrasound: resistive index calculation?

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.