18F-FDG

18F-FDG PET/CT is a widely used diagnostic tool in the management of oncologic diseases. Being an analog of glucose, the 18F-FDG uptake in cancer cells allows to detect growth and vitality during the time and distant metastases, in malignant tumors with high gradient of glucose metabolism. In these oncologic diseases, 18F-FDG is also currently useful as marker of response to therapy. Moreover, the use of this tracer is not limited to oncology but is involved in the evaluation of brain metabolism in neurodegenerative diseases, also with hybrid, simultaneous, PET/MR imaging, and in the detection of myocardial viability by means of PET imaging. The 18F-FDG follows, in vivo, the same biological pathway of glucose; after administration, it is taken up in cells with high glycolysis. Site of high rate of physiological uptake are the brain, myocardium, liver, spleen, and, due to renal excretion, kidneys, ureters, and bladder. During the time, several false positive cases have been described, due to the possibility of 18F-FDG uptake in inflammation, infections, and benign tumors. False negative cases can be due to malignant lesions with low rate of glucose metabolism.