PET-CT Before Surgery: — What Your Surgeon Needs to See

A CT scan shows the size and shape of structures but can miss spread to lymph nodes that appear normal in size and to distant organs where the abnormality is too subtle to see on anatomy alone. A PET-CT adds metabolic information — it shows which tissues are consuming glucose at a rate typical of cancer — so your surgeon gets a fuller picture of where the disease is before deciding how to operate. The two scans answer different questions, which is why both are sometimes needed.

Not necessarily. Surgeons order a PET-CT to find out whether spread has occurred before deciding on the operation — it is a question being asked, not an answer already known. For many patients the scan confirms that the cancer is where it appeared to be on earlier imaging, and surgery proceeds as planned. The scan is ordered because the surgeon wants certainty before committing to a major procedure, not because spread is assumed.

You will usually be asked to avoid eating for a number of hours before the scan, because the tracer is glucose-based and food affects how it distributes in the body. The exact instructions will be given to you by the imaging centre when the appointment is confirmed. Follow their specific guidance, and tell them in advance if you have diabetes or take medications that affect blood sugar, as the preparation may differ for you.

The most commonly used tracer is a radioactive form of glucose — FDG — that is absorbed by metabolically active cells, including cancer cells. It is given as an injection and the radioactivity is low and short-lived; it leaves the body within hours. The scan is considered safe for most adults. Tell the team if you are pregnant or breastfeeding before the appointment is confirmed, as additional precautions apply.

If the scan reveals spread that makes the planned surgery unsuitable, your team will discuss the alternatives. This often means treating the disease systemically first — with chemotherapy, targeted therapy or radiation — with surgery reconsidered once that treatment has had an effect. In some situations a different type of operation is planned instead. A change to the plan is not a closed door; it means the team now has the information to plan something that fits the disease as it actually is.

That depends on what the scan shows and whether additional steps are needed first — a confirmatory biopsy, a multidisciplinary team discussion, or a change in the treatment sequence. Your surgeon will give you a timeline once the result has been reviewed. If you have not heard within the timeframe they gave you, call the team rather than waiting. Asking for a clear timeline at your results appointment tells you exactly when to follow up.