Abstract: Conventional diagnostic techniques are not very accurate in detection tumor recurrence and restaging tumor. As a functional metabolic imaging modality, ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) PET can detect tumor recurrence at early stage, accurately differentiate postoperative scar from recurrence, and provide comprehensive information about restaging, but some false positive and false negative exist. Fusion PET and CT can help correctly interpret the PET image, and is accurate in location and diagnosis. Integrated PET-CT will have wider application in tumors.