背景：本回溯性研究的主要目的是評估氟－8-去氧葡萄糖正子電腦斷層掃描使用於甲狀腺球蛋白升高，但碘－131全身掃描結果陰性的甲狀腺癌病人之臨床應用。方法：從2003年8月至2006年11月，共有23位甲狀腺癌病人因爲疑似復發而至本院接受氟－18-去氧葡萄糖正子電腦斷層掃描。23位病人當中，男性佔14位，女性佔9位，年齡介於21-77歲，平均年齡爲53歲。所有病人均已接受甲狀腺全切除手術以及碘－131治療，但追蹤過程中發現甲狀腺球蛋白升高，而碘－131-全身掃描結果爲陰性。檢查當天，有8位病人的促甲狀腺激素大於30μIU/mL（高促甲狀腺激素），另外15位病人的促甲狀腺激素小於1μIU/mL（低促甲狀腺激素）。結果：本研究結果顯示17位病人之正子掃描結果爲陽性，其敏感度爲74%。17位病人當中，正子掃描總共發現25個病灶，其中包含：頸部14個、縱膈腔3個、肺4個、骨3個、骨周圍軟組織1個。另外，正子掃描結果也改變了8位病人的治療策略，其中6位病人接受頸部淋巴結摘除手術，1位病人接受頸部脊椎之放射線治療，1位病人接受頸部轉移性淋巴結之酒精注射治療。此研究中，有6位病人正子掃描結果爲陰性，其中3位病人於正子掃描後12個月內，被證實有頸部淋巴結轉移。本研究結果另外顯示高促甲狀腺激素並沒有提高正子掃描的敏感度。結論：本研究顯示，氟－18-去氧葡萄糖正子電腦斷層掃描能有效應用於復發性甲狀腺癌病人病灶的偵測。

Background: The aim of this study is to evaluate the clinical role of 18F-FDG (FDG) PET-CT in detecting recurrent or metastatic lesions in patients with well-differentiated thyroid cancer who have elevated serum thyroglobulin level but negative 131I whole body scan. Methods: A retrospective study was performed in 23 patients with recurrent well-differentiated thyroid cancer who underwent FDG PET-CT in our institute from August 2003 to November 2006. All of these patients had received total thyroidectomy and 131I treatment, and subsequently presented with elevated serum thyroglobulin but negative 131I whole body scan. Among these 23 patients, 8 patients performed FDG PET-CT during high thyroid stimulating hormone (TSH) level and 15 patients performed FDG PET-CT during low TSH level. In all patients, results of FDG PET-CT were correlated with conventional images, histopathological findings and clinical follow-up. Results: FDG PET-CT showed positive findings in 17 of 23 patients, giving a sensitivity of 74%. There were altogether 25 metastatic lesions being detected in these 17 patients, which comprised of 14 neck lesions, 3 mediastinal lesions, 4 lung lesions, 3 bone lesions and 1 soft tissue lesion. FDG PET-CT led to a change in management in 8 patients, in whom 6 patients received surgery, 1 patient received radiation therapy of bone metastasis and the remaining patient received alcohol injection of metastatic neck lymph node. In 6 patients with negative finding on FDG PET-CT, 3 patients developed neck recurrence within 12 months after PET study. In our study, the sensitivity of FDG PET-CT was not improved by high serum TSH level. Conclusion: FDG PET-CT is a reliable method for detecting recurrence in patients with well-differentiated thyroid cancer with elevated serum thyroglobulin and negative 131I whole body scan.