[PET/CT tomography. Usefulness in oncology]

In order to have optimum results in oncological patients, precise evaluation, diagnosis and staging of the patient is necessary. Positron emission tomography (PET) yields a high negative predictive value through exploration of the entire body. It diagnoses the benign or malignant state of a neoplasm that has been detected by other imaging methods and establishes an extensive diagnosis previous to therapeutic treatment of a known cancer. It identifies residual tumor and changes produced after surgery, chemotherapy or radiotherapy and locates suspicious residual tumor clinically or by elevation of the tumor markers. It allows for a new extension study or re-staging after diagnosis of recurrence and permits early evaluation of response to a therapeutic regime and permits the search for a primary tumor in patients with metastasis of unknown origin. PET leads to a molecular functional imaging of cancer in the entire body.