[Detection of residue of nasopharyngeal carcinoma with FDG PET].

Background And Objective: The use of F-18-fluoro-2-deoxy-d-glucose positron emission tomography (FDG PET) in detection of suspected residue of malignant tumor after treatment has become one of the most important targets of study in radiotherapy. This study was designed to evaluate FDG PET in detection of suspected residue of nasopharyngeal carcinoma (NPC) after treatment, in comparison with CT imaging.

Methods: Twenty-five patients with clinically suspected residue of NPC did FDG PET Scanning, 23 of them also examine with CT imaging. The diagnosis of residue were confirmed by pathology or clinical follow-up.

Results: FDG PET correctly detected residue in 19/25 patients. There were 4 false positive and 2 false negative patients. The accuracy of FDG PET was 76.0% (19/25), compared to 52.2% (12/23) of CT scan. Eleven of 23 patients did not show any residue by CT scan, while, FDG PET scan showed significantly increased FDG metabolism, indicating residue in 2 of these patients. In 7 patients, both CT and FDG PET indicated residue tumor.

Conclusion: Compared with CT imaging, FDG PET has a higher accuracy in detection of residue nasopharyngeal carcinoma after treatment.