SUV Values in — Infection and Inflammation

Not always, but often. When the clinical picture — your symptoms, blood tests and exposure history — clearly points toward infection and the finding is in a low-risk location, your team may treat empirically and repeat the scan to assess the response. When cancer cannot reasonably be excluded on clinical grounds, biopsy is usually recommended before treatment starts, because treating lymphoma as TB, or vice versa, carries serious risk. The decision depends on where the finding is, how certain the clinical picture is, and the procedural risk at that specific site.

Yes. Some cancers are relatively slow-growing and consume glucose at a rate that does not produce a noticeably elevated reading. Well-differentiated thyroid cancers, some mucinous tumours and certain low-grade lymphomas are examples where PET-CT is less sensitive. A normal or low SUV does not exclude cancer, which is why PET-CT is one tool in the diagnostic process rather than the only one.

Because blood tests and PET-CT measure different things, and cancer does not always alter blood counts or markers to a degree that shows up early. The phrase 'cannot exclude malignancy' means the radiologist sees a pattern consistent with cancer but cannot confirm it from the scan alone — it is not a statement about your blood tests. It is a prompt for your oncologist to decide whether biopsy is needed to settle the question.

A false positive is when the scan shows elevated uptake that looks concerning but turns out, on biopsy or follow-up, to be benign — infection, inflammation or a normal variant. False positives are well-documented with FDG PET-CT and are especially common in regions where tuberculosis and sarcoidosis are prevalent. They are not a sign that the scanner is faulty; they reflect the fact that SUV measures metabolic activity, and several conditions share that feature with cancer.

Yes. You are asked to fast before a PET-CT because elevated blood glucose competes with the radioactive tracer for uptake. If your blood sugar is high at the time of the scan — because of diabetes, inadequate fasting or stress — the tracer distributes differently and the images are harder to interpret. People with diabetes need specific preparation instructions from the scanning centre. Tell your team if you are diabetic or if you ate or drank anything before the scan.

A second opinion from a nuclear medicine physician or radiologist experienced in PET-CT interpretation is always reasonable, particularly when the finding is ambiguous and a major treatment decision rests on the scan. Bring your original images rather than just the printed report, because the images carry detail the written report may not fully capture. Your oncologist can also review the images with the reporting radiologist directly, which is often faster and more informative than a separate referral.