POSITRON EMISSION TOMOGRAPHY SCANNING
Positron emission tomography (PET) scanning is designed to assess the distribution of tracers labeled with positron-emitting nuclides, such as carbon-11 (11C), nitrogen-13 (13N), oxygen-15 (15O), and fluorine-18 (18F). Fluorodeoxyglucose (FDG), a glucose analogue labeled with 18F, can cross the blood-brain barrier. The metabolic products of FDG become immobile and trapped where the molecule is first used, thereby permitting FDG to be used to map glucose uptake in the brain.
This is a valuable tool for investigating subtle physiological processes related to neurological diseases. The distribution of FDG can be localized and reconstructed using standard tomographic techniques that show the tracer distribution through- out the body or brain. In this example of axial, sagittal, and coronal views, the transmission measurement and correction was performed immediately following PET acquisition using a 16-slice CT unit. The PET and CT images were automatically fused by anatomical coregistration software (shown as colored images).