Positron Emission Tomography-Computed Tomography, also known as Positron Emission Tomography or PET-CT scan, is a combined examination of both cellular structures and functions of the body. Apart from detecting pathological changes of tumour cells in the early stages and assessing the extent of metastasis, PET-CT scan can also be used to diagnose cardiovascular and neurological diseases, such as primary brain tumour, Alzheimer’s diseases and seizure.
PET-CT scan can display metabolic state of body cells. Prior to the scanning examination, radiotracers, commonly F-18 Fluorodeoxyglucose (FDG) that is a molecule similar to glucose, are injected intravenously. As tumour cells are more metabolically active and may absorb glucose at a higher rate, the rate of FDG uptake and emission of gamma rays can be detected by the gamma camera, which facilitates the localization of tumour cells. In case of infectious and inflammatory diseases, PET-CT also has the ability to detect the FDG uptake in granulomatous cells producing the inflammation.
On the other hand, CT uses a narrow X-ray beam operating at a high energy level to capture cross-sectional images of inside organs. By superimposing PET images with CT to produce special views, it allows doctors to better correlate and interpret both functional and anatomical information, leading to more precise and accurate diagnoses.
Below is the information regarding the uses, safety issues, concerns of undergoing a PET-CT examination and its advantages and limitations in comparison with other types of imaging modalities.