The Value of FDG-PET in Reoperation of the Recurrent Papillary Thyroid Carcinoma with Elevated Thyroglobulin Levels and Negative I131 WBS

ABSTRACT

PURPOSE: We evaluated the diagnostic accuracy and useful ness of FDG-PET to determine the proper extent of surgery in recurrent papillary thyroid cancer patients with elevated thyroglobulin levels and negative I131 WBS. METHODS: FDG-PET was performed in 16 recurrent papillary thyroid cancer patients with elevated thyroglobulin levels and negative I131 WBS. In 9 patients, FDG-PET was performed to localize the recurrent lesions. In 7 patients, the recurrent lesions were initially diagnosed by physical examination or other image studies and the FDG-PET was subsequently performed to detect additional recurrent lesions. All suspected lesions detected by FDG-PET and other studies were explored. RESULTS: Among the 9 patients in whom FDG-PET was performed to localize the recurrent lesions, the recurrent lesions were detected only by FDG-PET in 4 patients. Among the 7 patients in whom FDG-PET was performed additionally to detect additional recurrent lesions, another recurrent cervical regions were detected by FDG-PET in 2 patients. However, the same lesions were able to be identified by ultrasonography. A total of 26 cervical regions were explored in 16 patients. There were 4 FDG-PET false positive regions and 2 FDG-PET false negative regions. Unnecessary surgery was performed in 4 cervical regions in 4 patients. CONCLUSION: FDG-PET was very useful in detecting small early recurrent lesions but was unable to contribute to the detection of additional recurrent cervical regions in the pa-tients in which the recurrent lesion had already been by physical examination or other studies. Other image studies are necessary to supplement the FDG-PET in false positive or false negative cases.