An Fluorodeoxyglucose F 18 (FDG) PET/CT scan is a powerful, dual-action imaging technology used to detect, stage, and monitor cancer. By combining the metabolic insights of a PET scan with the precise structural map of a CT scan, it allows oncology teams to see both what a tumor looks like and how actively it is growing.
Why It Is Used
- Accurate Staging: Determines the exact size of a tumor and reveals whether cancer cells have spread to nearby lymph nodes or other organs.
- Treatment Monitoring: Checks how effectively a tumor is responding to chemotherapy, radiation, or immunotherapy, often long before structural changes show up on a standard X-ray.
- Recurrence Detection: Identifies if cancer has returned in patients who have completed treatment, even if scar tissue makes standard imaging difficult to read.
How It Works
- Metabolic Tracking: Cancer cells rapidly divide and consume significantly more energy than healthy cells, relying heavily on glucose (sugar) to grow.
- The Tracer: Patients receive an injection of fluorodeoxyglucose (FDG), a safe, microscopic amount of radioactive sugar that mimics normal glucose.
- Illuminating Tumors: The FDG tracer naturally pools in areas with high metabolic activity. The PET scanner detects these concentrations, causing active cancer cells to "glow" brightly on the screen.
The Procedure
- Preparation: Patients must fast (no food or sugar) for 4 to 6 hours before the test and strictly avoid strenuous exercise for 24 hours to ensure accurate results.
- The Wait Period: After the FDG injection, patients relax quietly in a private room for about 60 minutes to allow the tracer to fully distribute through the body.
- The Scan: Patients lie flat on a motorized table that slides smoothly into the scanner. The imaging process is completely painless and takes roughly 20 minutes.
- Aftercare: The tracer naturally decays and leaves the body through urine. Drinking plenty of water and emptying the bladder frequently after the appointment accelerates this process.
Safety and Benefits
- Early Detection: Finds cellular changes at a microscopic level, often detecting disease months before it causes visible anatomical changes on standard CTs or MRIs.
- Minimal Radiation: The radiation dose from the tracer is small, highly controlled, and safely clears out of the patient's system within 24 hours.