Glucose consumption in tissue can be measured using positron emission tomography (PET) and 18F-deoxyglucose (18FDG). Malignant tumors rely largely on anaerobic glycolysis and show very rapid glucose consumption, and can therefore be imaged using PET and 18FDG. PET has been shown to be useful in the evaluation of patients with e.g. lung cancer, colo-rectal cancer, malignant melanoma and malignant lymphoma, in terms of both diagnostic accuracy and cost-effectiveness. The clinical use of PET for workup of cancer patients is increasing rapidly in North America as well as in the European Union, but Sweden is lagging behind.