Nuclear medicine: lung ventilation-perfusion: 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 · Nuclear medicine: lung ventilation-perfusion

Sample item

A V/Q scan shows multiple segmental perfusion defects with normal ventilation in the same regions. What does this mismatch pattern indicate?

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

The answer and the reasoning

B. High probability for pulmonary embolism

Embolic occlusion stops perfusion while ventilation is preserved, producing a mismatch. In COPD or pneumonia both ventilation and perfusion are decreased (matched defects). Macroaggregated albumin labelled with Tc-99m is used for perfusion.

Option by option

  • A. Pneumonia

    Pneumonia gives matched defects.

  • B. High probability for pulmonary embolism (correct)

    Correct. Segmental perfusion defects with normal ventilation signal PE.

  • C. Normal scan

    Segmental defects mean the study is abnormal.

  • D. COPD

    COPD gives matched defects.

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, High probability for pulmonary embolism. Embolic occlusion stops perfusion while ventilation is preserved, producing a mismatch.

Why is "Pneumonia" not the answer?

Pneumonia gives matched defects.

Why is "Normal scan" not the answer?

Segmental defects mean the study is abnormal.

Why is "COPD" not the answer?

COPD gives matched defects.

What concept does this question test?

It tests Nuclear medicine: lung ventilation-perfusion in Radiology. In COPD or pneumonia both ventilation and perfusion are decreased (matched defects). Macroaggregated albumin labelled with Tc-99m is used for perfusion.

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 Nuclear medicine: lung ventilation-perfusion?

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.