Nuclear medicine: 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

Sample item

In FDG-PET imaging, why does the tracer accumulate in many malignant tumours?

AIt is a glucose analogue trapped after phosphorylation in cells with high glycolysisBIt binds to specific receptors on tumour cell membranesCIt is taken up by osteoblasts during new bone formationDIt is concentrated by the sodium-iodide symporter

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

The answer and the reasoning

A. It is a glucose analogue trapped after phosphorylation in cells with high glycolysis

Fluorodeoxyglucose enters cells like glucose, and hexokinase phosphorylates it. The product cannot proceed down the glycolytic pathway, so it is trapped. Tumour cells with high glycolytic activity therefore appear as hot spots on the scan.

Option by option

A. It is a glucose analogue trapped after phosphorylation in cells with high glycolysis (correct)
Correct. Metabolic trapping in glucose-avid cells forms the basis of the image.
B. It binds to specific receptors on tumour cell membranes
FDG is not a receptor-binding ligand.
C. It is taken up by osteoblasts during new bone formation
Uptake by osteoblasts describes bone-seeking tracers such as bone scan agents.
D. It is concentrated by the sodium-iodide symporter
The sodium-iodide symporter concentrates radioiodine in thyroid tissue, not FDG.

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.

Questions about this Radiology question

What is the answer to this Radiology question?

The best answer is A, It is a glucose analogue trapped after phosphorylation in cells with high glycolysis. Fluorodeoxyglucose enters cells like glucose, and hexokinase phosphorylates it.

Why is "It binds to specific receptors on tumour cell membranes" not the answer?

FDG is not a receptor-binding ligand.

Why is "It is taken up by osteoblasts during new bone formation" not the answer?

Uptake by osteoblasts describes bone-seeking tracers such as bone scan agents.

Why is "It is concentrated by the sodium-iodide symporter" not the answer?

The sodium-iodide symporter concentrates radioiodine in thyroid tissue, not FDG.

What concept does this question test?

It tests Nuclear medicine in Radiology. The product cannot proceed down the glycolytic pathway, so it is trapped. Tumour cells with high glycolytic activity therefore appear as hot spots on the scan.

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?

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.