Radiotherapy and nuclear medicine basics: PET-CT in an unknown primary: 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 · Radiotherapy and nuclear medicine basics: PET-CT in an unknown primary

Sample item

A man has a squamous carcinoma in a cervical lymph node. Examination, endoscopy and CT do not show a primary. Which imaging is most useful to find it?

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

The answer and the reasoning

D. FDG PET-CT

FDG PET-CT detects metabolically active primary tumours that anatomical imaging misses and identifies the primary in a substantial proportion of unknown primary cases in the head and neck. Bone and thyroid scans and chest radiography are unlikely to identify a squamous primary.

Option by option

  • A. Thyroid scintigraphy

    Thyroid scintigraphy is not used to find a squamous carcinoma.

  • B. Bone scintigraphy

    Bone scintigraphy looks for skeletal metastases, not a squamous primary.

  • C. Chest radiograph

    A chest radiograph would miss a small primary and adds little.

  • D. FDG PET-CT (correct)

    Correct. FDG PET-CT finds occult metabolically active primaries.

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, FDG PET-CT. FDG PET-CT detects metabolically active primary tumours that anatomical imaging misses and identifies the primary in a substantial proportion of unknown primary cases in the head and neck.

Why is "Thyroid scintigraphy" not the answer?

Thyroid scintigraphy is not used to find a squamous carcinoma.

Why is "Bone scintigraphy" not the answer?

Bone scintigraphy looks for skeletal metastases, not a squamous primary.

Why is "Chest radiograph" not the answer?

A chest radiograph would miss a small primary and adds little.

What concept does this question test?

It tests Radiotherapy and nuclear medicine basics: PET-CT in an unknown primary in Radiology. Bone and thyroid scans and chest radiography are unlikely to identify a squamous primary.

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 Radiotherapy and nuclear medicine basics: PET-CT in an unknown primary?

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.