What is a PET scan done for?

A PET-CT combines a metabolic picture from FDG Radiotracer with a CT picture of body structures. This can help show whether a suspicious area is active, whether disease involves nearby lymph nodes or other organs, and whether treatment appears to be changing the pattern of activity. It may also help select a safe and useful site for biopsy or clarify a finding that another scan could not fully explain.

A PET-CT is not automatically needed for every tumour or symptom. The value depends on the clinical question, the body area, previous imaging, and the type of suspected disease. For example, it may form part of an assessment for Lymphoma or Cancer of Unknown Primary.

Use the appointment instructions as your preparation plan. Tell the imaging team about diabetes, medicines, pregnancy, breastfeeding, recent infection, or strenuous exercise. They may give specific directions about food, fluids, and medication because glucose levels and muscle activity can affect the images. Bring relevant reports and arrive with time for registration, tracer administration, a quiet rest, and the scan. Do not change prescribed medicines unless the clinical team tells you to.

Call before attending if you are unwell, cannot complete the preparation, or may be pregnant. Following the appointment, get urgent help for severe breathing difficulty, swelling of the face or throat, collapse, or a rapidly worsening condition. For non-urgent concerns, contact the imaging service about the tracer or appointment instructions rather than waiting for the report.

What specific decision will this scan help with? Is it being used for diagnosis, staging, treatment planning, or monitoring? How might the result change my next step? Are there alternatives, and when will the findings be reviewed with me?