PET-CT for Neuroendocrine Tumours: — FDG or DOTATATE?

Possibly, but timing matters. Long-acting somatostatin analogues such as octreotide LAR and lanreotide can compete with the DOTATATE tracer for the same receptors, which may reduce how clearly the tumour appears on the scan. Your team may ask you to wait a defined interval after your last injection before booking. Tell your oncologist and the imaging centre exactly when your last dose was given. Do not skip a dose on your own — that decision depends on your overall management plan.

DOTATATE binds to somatostatin receptors, which are found on the surface of well-differentiated neuroendocrine tumour cells. The tracer makes those cells visible on the scan as areas of increased uptake. It can detect the primary tumour and any spread to lymph nodes, liver, bone, or other sites. It does not show tumours that do not express somatostatin receptors, which is why high-grade NETs and neuroendocrine carcinomas are often invisible on a DOTATATE scan.

Not necessarily, and for low-grade NETs a normal FDG scan is expected rather than reassuring. Well-differentiated neuroendocrine tumours use so little glucose that FDG often shows nothing even when the tumour is still present and growing slowly. Your oncologist will interpret the FDG result alongside your DOTATATE scan, your symptoms, and your other investigations. A normal FDG scan in isolation is not a clear result without that full context.

Both scans are ordered when one tracer alone cannot show the full picture. This commonly happens when grade is uncertain, when different areas of the tumour appear to be behaving differently, or when a previously stable tumour starts growing more quickly. Comparing what each tracer shows helps your oncologist understand whether all the disease is well-differentiated or whether a more aggressive component has developed — which directly changes the treatment approach.

Yes. DOTATATE PET-CT is available at specialist nuclear medicine centres in India and is used routinely for neuroendocrine tumours. Access varies by city, and your oncologist will coordinate a referral to an appropriate imaging centre. At CION, PET-CT scans are coordinated with partner imaging centres. Ask your team which centre has been arranged for you and what preparation you will need before you travel.

Ki-67 measures how fast tumour cells are dividing, reported as a percentage from your biopsy sample. A low Ki-67 indicates a slowly growing tumour that is likely to express somatostatin receptors — the right target for DOTATATE. A high Ki-67 indicates rapid growth, and these tumours tend to be metabolically active enough for FDG to detect. When Ki-67 sits in an intermediate range, your oncologist may use both scans together to guide treatment decisions. Ask your team what your Ki-67 result is if you have not been told.