FDG PET imaging in the follow up of nasopharyngeal carcinoma

Objective To investigate the clinical value of FDG PET imaging in the follow up of nasopharyngeal carcinoma after radiotherapy. Methods Twelve patients with nasopharyngeal carcinoma underwent FDG PET, CT and/or MRI during the follow up of 12 18 months after radiotherapy. The results of FDG PET were double blind evaluated and compared with these of CT and MRI. The recurrent lesions in six of these patients were pathologically confirmed and six by CT scan. Results Nine of 12 patients did not show any recurrence by CT and MRI scans. However, FDG PET scans showed significantly increased FDG metabolism, indicating recurrence in 3 of these patients. In 2 patients, both CT/MRI and FDG PET indicated recurrence. The remaining one patient had radiotherapy induced cerebral necrosis. He was misdiagnozed as an intracranial recurrence by MRI, but FDG imaging was negative. Conclusions FDG PET imaging has an advantage in distinguishing the relapse or necrosis in the follow up of post radiotherapy nasopharyngeal carcinoma patients. PET, CT and MRI is able to give a detail both in morphological and functional changes of disease. They are especially useful in the follow up or the set up of treatment planning for recurrent nasopharyngeal carcinoma.