A PET scan (Positron Emission Tomography) is an imaging technique widely used in oncology and other medical fields.
Here’s a pharmacist-focused definition:
PET Scan (Positron Emission Tomography)
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Principle: Uses a radioactive tracer (commonly 18F-fluorodeoxyglucose, FDG) that mimics glucose.
- Cancer cells have high metabolic activity, so they uptake more FDG.
- The tracer emits positrons, which collide with electrons, producing gamma rays detected by the scanner.
- Result: A 3D image showing areas of increased metabolic activity (often cancer).
Oncology Uses
- Diagnosis & staging: Detects primary tumors and metastatic disease.
- Treatment planning: Guides surgery, radiation, and systemic therapy.
- Response assessment: Evaluates early response to chemotherapy, targeted therapy, or immunotherapy.
- Surveillance/recurrence detection: Helps detect relapse earlier than CT/MRI in some cancers.
Pharmacist Considerations
- Tracer: Most common is 18F-FDG (glucose analog).
- Patient prep:
- Fasting (≥6 hrs) to reduce background glucose uptake.
- Avoid strenuous exercise (prevents muscle uptake).
- Blood glucose control: Hyperglycemia can reduce test accuracy.
- Limitations:
- Not all cancers are FDG-avid (e.g., prostate, some indolent lymphomas).
- False positives from infection/inflammation (↑ metabolic activity).
- Radiation exposure: Low-to-moderate, but cumulative over multiple scans.
In oncology practice, PET is often combined with CT (PET/CT) for both metabolic and anatomical information.