ABSTRACT
Positron-emission tomography (PET) imaging with 18F-fluorodeoxyglucose (FDG) has the unique capability of visualizing intracellular biochemical processes. Tumour cells display to some extent increased expression of glucose membrane transporters, enhanced glycolysis, or both. FDG is a glucose analogue, and cells take it up proportionally to the strength of these phenomena.1 Unlike glucose, FDG is only phosphorylated by hexokinase and not further metabolized. It thus accumulates in glucoseavid tissues such as tumours. In recent years, PET has become a major tool for diagnosing and staging various neoplastic conditions, including colorectal carcinoma. The originality of the technique results from both the metabolic features of the signal and the technological improvements that have permitted its use in a clinical setting. Indeed, modern scanners now provide high-quality, fully corrected images of the whole body. These studies are performed in a time frame compatible with a clinical environment. In particular, image reconstruction using iterative algorithms and a more generalized utilization of attenuation correction have greatly improved the image quality and the clinical relevance of PET studies. An example of a normal study is shown in Figure 28.1.
