POSITRON EMISSION TOMOGRAPHY FOR PREOPERATIVE STAGING OF COLORECTAL-CARCINOMA

PURPOSE: Positron emission tomography (PET) is an imaging technique ba sed on in vivo cellular metabolism. Increased glucose metabolism in ne oplastic cells is detected by using fluorine-18 deoxyglucose. In an on going pilot study to determine the usefulness of this technique, PET i s compared with computerized tomography (CT) for the preoperative stag ing of colorectal carcinoma. METHODS: Sixteen patients were evaluated with both PET and CT of the abdomen and pelvis. Results were compared with operative and histopathologic findings. Fifteen malignant lesions were found in 16 patients by histology. PET had a positive predictive value of 93 percent and a negative predictive value of 50 percent. By comparison CT had a positive predictive value of 100 percent and a ne gative predictive value of 27 percent. CONCLUSIONS: These preliminary results indicate that PET has increased sensitivity for staging colore ctal carcinoma, whereas CT has higher specificity. The predictive valu e of a positive PET compares favorably with CT. Furthermore, the predi ctive accuracy for detection of colorectal carcinoma is 83 percent for PET and 56 percent for CT.