PETskanning

PET scanning, or positron emission tomography, is a nuclear medicine imaging technique that visualizes metabolic and molecular processes in the body. It uses short-lived positron-emitting radiotracers, most commonly fluorine-18 labeled fluorodeoxyglucose (FDG), injected into the patient. After injection, tracer uptake is allowed for about 30 to 60 minutes, then a PET scanner detects pairs of gamma photons produced by positron annihilation. A computer reconstructs images that reflect regional tracer concentration, often expressed as standardized uptake values (SUVs).

Because many diseases alter metabolism, PET provides functional information that complements anatomic imaging. The modality is frequently combined with computed tomography (PET/CT) or magnetic resonance imaging (PET/MRI) to provide precise localization. Common tracers include FDG for glucose metabolism; other tracers target myocardial perfusion, amino acid transport, receptor expression, or specific biochemical pathways in oncology and neurology.

Applications include oncology for detecting tumors, staging, and monitoring response to therapy; neurology for epilepsy focus localization and investigation of dementias; and cardiology for assessment of myocardial perfusion and viability.

Procedure and safety considerations include fasting and blood glucose control before FDG PET. The exam involves exposure to a small amount of ionizing radiation, and most patients experience minimal risk. Limitations include limited spatial resolution, potential false positives from infection or inflammation, and high cost and limited availability. Results are interpreted in the context of clinical data and other imaging studies.