PET-FDG imaging

Positron emission tomography with 18F-fluorodeoxyglucose (FDG-PET), typically combined with low-dose CT for attenuation correction and anatomical co-registration (PET/CT), images regional glucose metabolism. The effective dose is roughly 5–10 mSv (~7 mSv for FDG alone plus the CT component). Established indications include initial staging and response assessment in lymphoma, lung, head-and-neck, oesophageal, colorectal, melanoma and many other cancers, detection of recurrence, evaluation of cardiac sarcoidosis and infection of prosthetic material, and differentiation of dementia subtypes (Alzheimer- versus frontotemporal-pattern hypometabolism). FDG is not specific for tumour cells – inflammation, infection and brown adipose tissue also avidly take up glucose – so false positives are common. FDG-PET is not validated as a routine longevity or whole-body screening test in asymptomatic adults because of the high incidentaloma rate, radiation exposure and cost. Standardised acquisition follows EANM procedure guidelines.