Positron emission tomography (PET) and [F-18]-fluorodeoxyglucose (FDG) in cancerology

Positron emission tomography (PET) with F-18-fluorodeoxyglucose (FDG) is a scintigraphic imaging technique undergoing a rapid growth in the field of oncology. The constant progress of the detectors, either CDET or PET dedicated cameras, allows to obtain in routine conditions images with a 5 mm spatial resolution. Absolute tracer uptake quantification is also possible, which allows to evaluate objectively therapy efficacy. The mechanisms of FDG tissular accumulation are now better understood. Increase of glycolysis and of transmembrane transport of glucose seems to be at the origin of the high tumorous accumulation of FDG. The main current oncologic application of FDG PET is in the diagnosis of malignancy of the isolated pulmonary nodules, with a sensitivity of more than 95%, and in the staging of lung cancer where PET shows higher performances than conventional imaging. The same stands in cutaneous melanoma and for malignancies of the digestive tract, either in colorectal, pancreatic or esophageal localizations. In colorectal cancers, the role of PET has for long being recognized in the differential diagnosis between recurrence and postoperative fibrosis. In the head and neck tumors, FDG also allows to differentiate between recurrence and postradiation necrosis. In lymphoma, the most suitable site for biopsy can be identified on a PET scan and therapy efficacy can also be assessed. In breast cancer, the detection of metastases seems to be possible with FDG. In brain and thyroid cancers, the role of FDG PET remains to be further determined. The low uptake of FDG in prostate cancer metastasis is not in favor of its use in this indication. In conclusion, the indications of FDG PET in oncology are now becoming more precise and it can be expected that clinical PET centers will soon appear in France.