Question

What is the investigation of choice for neuroendocrine tumors?

• A. Endoscopic USG
• B. SPECT
• C. Radionuclide study
• D. MRI

Hint:

NET cells carry somatostatin receptors; a receptor-targeted radionuclide scan (octreotide/DOTATATE) finds the tumor and any spread in one test.

Answer 1

The Correct Option is C

This question tests knowledge of the best imaging method to find and stage a neuroendocrine tumor (NET), a tumor type that arises from hormone producing cells scattered through the gut, pancreas, and lungs.

1. Endoscopic USG: Good for spotting a small pancreatic NET up close, but it only looks at one region and cannot check for spread to the liver or bones.
2. SPECT: This is a camera technique, not a tracer. It becomes useful only when paired with a receptor-seeking tracer, so on its own it is not the full answer.
3. Radionuclide study: NET cells are rich in somatostatin receptors. A tracer such as labeled octreotide binds these receptors, so a single whole-body radionuclide scan finds the primary tumor and any secondary spread together. This is why it is preferred.
4. MRI: Shows soft tissue detail and organ anatomy well, but it cannot tell a NET apart from other masses unless the tumor is already large enough to see.

The correct choice is the radionuclide study (somatostatin receptor scintigraphy, now often done as Ga-68 DOTATATE PET/CT), because it targets a feature unique to NET cells and covers the whole body in one test.

Let's summarize:

• NETs express somatostatin receptors on their surface.
• A receptor-targeted radionuclide scan can find both the primary tumor and metastases in a single study.

So the investigation of choice for neuroendocrine tumors is the radionuclide study.