[Positron emission tomography (PET): application in urogenital system oncologic diseases]

To review and discuss the applications of positron emission tomography (PET), with special reference to genitourinary tumors.

Our experience and the relevant literature on PET are reviewed. The principles and technical aspects of PET, the different parameters analyzed, its clinical indications, applications in genitourinary tumors and research are discussed.

Positron emission tomography (PET) permits visualization and determination in vivo of a number of tissue and organ physiologic and biomolecular parameters. PET is also used for biomedical research and is especially useful for research and development of new drugs, tumor biomolecular phenotyping and for monitoring gene therapy. It has also proved to be a useful non-invasive diagnostic imaging technique in the clinical setting with an excellent cost-effectiveness in cancer patients. Fluor-deoxyglucose-F18 or FDG is the only radiotracer with a clinical application. PET detects the intense tumor uptake of FDG due to the higher glycolytic index of tumor cells. The PET tomograms allow performing a complete study of the whole body in the same session. The clinical indications of FDG PET that are currently accepted and established are: diagnosis of benign versus malignant solitary lung nodule, pre-treatment study to determine the extent of non-small cell lung cancer, localization and re-staging of colorectal cancer recurrence, extent and post-treatment assessment of lymphomas and extent of recurrent malignant melanoma. The application of FDG PET in genitourinary cancer is controversial. It does not appear to be useful in the initial diagnosis of primary prostatic, bladder and kidney tumors. Its clinical yield appears to be better for localizing recurrence and re-staging patients with increased prostatic specific antigen (PSA) levels after treatment of a primary prostatic tumor. Furthermore, it can also be used to determine the extent of hypernephroma and malignant bladder tumor suspected to be metastatic at the initial diagnosis. In testicular germ cell tumors, FDG PET can be a very useful tool for pre-treatment staging and to evaluate post-treatment residual masses.