Summary
Highlights
18F-FDG glucose has a short half-life, meaning its radioactivity decreases rapidly. The radiation dose from a PET/CT scan is roughly equivalent to the average annual natural background radiation. Currently, PET/CT primarily produces static images of metabolic processes, but future developments aim for dynamic imaging to capture and quantify these processes over time, offering even more comprehensive diagnostic and monitoring capabilities.
PET/CT combines Positron Emission Tomography (PET) and Computed Tomography (CT) into a single scan. This highly sensitive test allows for the precise localization and early evaluation of physiological changes by integrating metabolic process measurements from PET with high-resolution anatomical images from CT. This combination provides a more accurate picture than separate scans, aiding in earlier diagnosis.
Physicians use PET/CT scans for detecting tumors and metastasis, distinguishing between malignant and benign changes, determining disease stages, developing treatment strategies, and monitoring treatment response. It is also valuable in evaluating Alzheimer’s disease and heart disease.
PET measures metabolic activity using weakly radioactive biomolecules called PET tracers. These tracers behave like normal biomolecules and accumulate in areas with higher metabolic activity. The PET scanner records the distribution of the tracer, showing these active areas as bright spots on the scan.
While various biomolecules can be tracers, radioactive labeled glucose (18F-FDG) is most commonly used. This tracer accumulates in tissues and organs with high energy demand but decays quickly, requiring fresh preparation for each examination. Patients receive an intravenous injection of the tracer, rest for an hour to allow distribution, and then undergo the combined PET/CT scan. CT uses X-rays for anatomical imaging, while PET registers the tracer's decay via gamma rays, resulting in a fused image.