PET-CT in Leukaemia: — When Is It Used?

There is usually a specific clinical reason — something in your blood tests, your symptom pattern, or a previous scan that makes PET-CT the right next step. The most common reasons are suspicion of Richter's transformation in CLL, a possible chloroma in AML, or pre-transplant assessment. Ask your haemato-oncologist what question the scan is intended to answer — that is the most useful way to understand why it has been ordered for you.

In lymphoma, PET-CT is central to staging, treatment response, and the decision about whether to continue or change treatment. In leukaemia, bone marrow biopsy and blood counts carry most of that weight, because leukaemia lives in the marrow rather than forming the solid node masses that PET reads so clearly. PET-CT in leukaemia is reserved for specific situations rather than used routinely.

Not necessarily, and this is one of the reasons PET-CT is not used to monitor most leukaemia types. A normal PET result means there are no areas of elevated glucose uptake visible — but leukaemia in the blood and marrow can be present without producing a clear signal. Molecular tests on blood and bone marrow are far more sensitive for detecting minimal residual disease. Your team will tell you which tests are being used to assess your response.

FDG-avid means an area is taking up the radioactive glucose tracer above the expected background level. What that means clinically is something your haemato-oncologist interprets in the context of your whole picture — an FDG-avid node in someone with CLL, for example, may be the first sign of Richter's transformation, which carries very different implications from a mildly active node that has been stable for months. The report describes what the scan shows; your team places it in context.

PET-CT uses a small amount of radioactive glucose and a CT component. Both involve radiation, but at doses considered safe for diagnostic use by international imaging guidelines. The scan takes around an hour and requires only the injection and time in the scanner. At CION, PET-CT is coordinated with partner imaging centres; your haemato-oncologist will order the scan and specify the timing in the context of your treatment.

You can raise it as a question, and your doctor should be able to explain whether it would add information that changes your management. For most leukaemia types, a PET-CT ordered without a specific clinical reason is unlikely to alter the treatment plan and exposes you to radiation without benefit. If you feel your disease is not being adequately assessed, a second opinion from another haemato-oncologist is usually the more useful step.