RESUMEN
<p><b>OBJECTIVE</b>To investigate the diagnostic value of F-18-fluoro-deoxyglucose positron emission tomography (FDG-PET) for the recurrent or residual nasopharyngeal carcinomas in the skull base area.</p><p><b>METHODS</b>Nine post-irradiation nasopharyngeal carcinoma patients did FDG-PET scanning, CT/MRI imaging and underwent nasopharynx and skull base-biopsy under endoscopy. The results of FDG-PET were evaluated and compared with CT/MRI studies and biopsies.</p><p><b>RESULTS</b>In 9 cases of post-irradiation nasopharyngeal carcinoma, CT/MRI detected 7 recurrent cases and 2 suspected recurrent cases in occipital bone and clivus. All 9 cases had accumulated FDG in nasopharynx and cranial base. A definite diagnosis was made by biopsy, 3 cases were confirmed recurrence, and others 6 cases were proved mucous chronic inflammation and (or) osteoradionecrosis. The accuracy of FDG-PET was 33.3% (3/9), and the false positive rate was 66.7% (6/9).</p><p><b>CONCLUSIONS</b>Diagnosis of recurrent or residual nasopharyngeal carcinomas in the skull base area with FDG-PET had high false-positive rate, final diagnosis must depend on histopathologic examination under endoscopy.</p>