PETimaging

PET imaging, or positron emission tomography imaging, is a nuclear medicine technique that uses positron-emitting radiotracers to visualize metabolic and molecular processes in the body. After administration, tracer uptake reflects biological activity in tissues. Detectors capture pairs of gamma photons from positron annihilation, allowing the reconstruction of three-dimensional images. PET is often combined with computed tomography or magnetic resonance imaging to provide anatomic localization, resulting in PET/CT or PET/MRI studies. Attenuation correction is commonly applied to improve image accuracy.

The most widely used tracer is 2-deoxy-2-[18F]fluoro-D-glucose (FDG), which mirrors glucose metabolism. Other tracers target perfusion, receptor expression, hypoxia, and protein aggregates such as amyloid and tau for Alzheimer's disease, as well as various neurotransmitter systems. Radiotracers have short physical half-lives, necessitating on-site production or rapid distribution from a nearby radiopharmacy or cyclotron.

Applications of PET imaging span several fields. In oncology, it assists in tumor detection, staging, monitoring response to therapy, and identifying recurrence. In neurology, it helps localize epileptic foci and study neurodegenerative disorders. In cardiology, it assesses myocardial perfusion and tissue viability. In research, it enables investigation of molecular pathways and the effects of new drugs.

Limitations and safety considerations include relatively limited spatial resolution compared with CT or MRI, partial-volume effects, high cost, and radiation exposure. The dose depends on the tracer and administered activity but is generally within standard diagnostic imaging ranges. Advances continue in improving resolution, developing new tracers, and combining modalities to enhance diagnostic accuracy.