Prior studies have demonstrated that FDG uptake is greater in inflamed tissues, such as infectious foci and tumors. In chronic inflammatory lesions and malignancies, FDG uptake is increased in macrophage-dense regions. The relatively high uptake of FDG by macrophages is attributed to the relatively high metabolic rates of macrophages, and the inability of macrophages to store glycogen, making them more reliant upon external glucose as a source of fuel. Activation of macrophages can further increase their glucose consumption. Both in animal models and humans, inflamed blood vessels have been shown to have an increased uptake of FDG. Several investigators have shown that FDG-PET can reliably detect inflammation in atherosclerosis. Thus detection of enhanced FDG uptake in the aneurysmal walls of patients with AAA may have potential significance.