Nuclear medicine: sentinel lymph node: 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: sentinel lymph node

Sample item

A woman with early breast cancer is to have sentinel node biopsy. Which preoperative nuclear imaging is used?

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

The answer and the reasoning

D. Peritumoural injection of a technetium-99m labelled colloid for lymphoscintigraphy

A colloid labelled with technetium-99m, injected around the tumour, drains to the first lymph node, which is mapped on imaging and located in theatre with a gamma probe. It spares many patients a full axillary dissection.

Option by option

  • A. Intravenous thallium-201

    Thallium is a myocardial perfusion tracer.

  • B. Oral iodine-131

    Oral radioiodine is thyroid specific.

  • C. Intravenous gallium-67

    Gallium is not used for node mapping.

  • D. Peritumoural injection of a technetium-99m labelled colloid for lymphoscintigraphy (correct)

    Correct. Lymphoscintigraphy maps the first draining node.

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 D, Peritumoural injection of a technetium-99m labelled colloid for lymphoscintigraphy. A colloid labelled with technetium-99m, injected around the tumour, drains to the first lymph node, which is mapped on imaging and located in theatre with a gamma probe.

Why is "Intravenous thallium-201" not the answer?

Thallium is a myocardial perfusion tracer.

Why is "Oral iodine-131" not the answer?

Oral radioiodine is thyroid specific.

Why is "Intravenous gallium-67" not the answer?

Gallium is not used for node mapping.

What concept does this question test?

It tests Nuclear medicine: sentinel lymph node in Radiology. It spares many patients a full axillary dissection.

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 Nuclear medicine: sentinel lymph node?

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.