The significance of ~(18)F-FDG PET/CT imaging in the follow up of nasopharyngeal carcinoma after radiotherapy

Objective To investigate the clinical value of whole-bocy 18F-FDG PET/CT imaging in early detecting the recurrence of nasopharyngeal carcinoma after radiotherapy. Methods 20 patients with nasopharyngeal carcinoma underwent 18F-FDG PET/CT and MRI examination during the following 12 to 18 months after radiotherapy. The diagnoses of 18F-FDG PET/CT、MRI were obtained by nuclear physicians and radiologists independently. The results of them were compared with each other. The final results were proved by follow up and pathological evidence. The recurrent lesions in 12 of these patients were pathologically confirmed. Results 11 patients did not show any recurrence on MRI scans. However, 18F-FDG PET/CT scans showed focal FDG uptake activity in the region of primary tumor , indicating recurrence in 5 patients. In 7 patients , both MRI and 18F-FDG PET/CT indicated recurrence. The remaining two patients had radiotherapy induced reaction. They was wrongly diagnosed as an intracranial recurrence by MRI, but 18F-FDG PET/CT scan showed no recurrence and suggested radiation encephalopathy. Conclusions Compared to MRI 18F-FDG PET/CT imaging has an advantage in distinguishing the relapse or post-radiotherapy changes in. nasopharyngeal carcinoma patients.