PET-CT for Melanoma: — When It Works and What It Misses

For most stage I and II melanoma, PET-CT is not part of standard staging. The likelihood of detectable distant spread at these stages is low, and NCCN does not recommend it routinely. Ultrasound of regional nodes or a sentinel lymph node biopsy may be used for regional assessment depending on your risk factors, but whole-body PET-CT is generally reserved for stage III and IV disease. If yours has been ordered at an earlier stage, ask your oncologist what clinical finding prompted that decision.

PET-CT cannot reliably detect brain metastases. The brain's continuous, high glucose use creates background signal that masks small deposits — MRI is far more sensitive there. Ordering both scans is standard practice for advanced melanoma because they complement rather than duplicate each other. The PET-CT maps systemic spread throughout the body; the MRI examines the brain. Having both ordered is not a sign that something unexpected is being investigated.

No. Sentinel lymph node biopsy examines tissue directly under a microscope and can detect microscopic clusters of melanoma cells well below what any imaging can see. PET-CT is not sensitive enough to replace it for surgical staging decisions in early disease. The two serve different purposes at different stages: biopsy stages regional nodes surgically in earlier disease, while PET-CT maps whole-body spread in stage III and IV. Your surgical and oncology teams will advise which applies to your situation.

It means your treatment plan will be reviewed — not that a decision is made on the spot. Your oncologist will consider the location and number of sites, the pattern of spread, and your overall fitness. Systemic options such as immunotherapy or targeted therapy are typically discussed for stage IV disease. Some PET-CT findings are confirmed by biopsy before treatment begins, particularly when the result would significantly change the approach. A positive scan starts a conversation, not an automatic protocol.

There is no single schedule — the timing depends on your treatment and how your disease is responding. For patients receiving immunotherapy or targeted therapy, scans are typically done at intervals set by your oncologist, often every few months in the early treatment phase. Your team will give you a specific plan and explain what they are looking for at each point. If you are unsure when your next scan is or why, your care coordinator can clarify.

Yes. PET-CT scans are coordinated through CION's partner imaging centres across the network. Your oncologist will arrange the referral, and the report will be reviewed with you at your next appointment. CION does not own PET-CT scanners directly — the scan takes place at a partner centre and the results return to your treating team. Your care coordinator can tell you which centre will be used, how to prepare, and how long results typically take at your location.