Abstract: 18F-fluorodeoxyglueose (¹⁸F-FDG) PET is a king of functional imaging technique. It can reveal occult distant melastases on routine imaging. It has a significant clinical impact on detecting cervical nodal involvement, distant metastasis. ¹⁸F-FDC PET is also superior to conventional anatomic imaging modalities in monitoring curative effect and differentiating recurrent or residual disease from therapy-induced changes in nasopharyngeal carcinoma. Compared with CT and MRI, the inherent limitation of ¹⁸F-FDG PET is poor anatomic resolution. Combined PET and CT (PET-CT) can often overcome these difficulties by fusing anatomic and physiological data.