目的 探讨¹⁸F-FDG PET/CT显像在血清Tg和¹³¹I全身扫描均为阴性的行甲状腺癌切除和清除残留甲状腺组织治疗后的患者中检测肿瘤复发和转移的应用价值。方法 41例接受了甲状腺全切和大剂量¹³¹I清除残留甲状腺组织治疗的DTC患者，在随访中进行了血清Tg测定、¹³¹I-WBS、颈部B超、胸部CT及¹⁸F-FDG PET/CT全身显像。结果 41例患者血清Tg和¹³¹I-WBS均为阴性，颈部B超或胸部CT均显示存在异常病灶；其中23例患者¹⁸F-FDG PET/CT显像阳性，18例患者¹⁸F-FDG PET/CT显像阴性。¹⁸F-FDG PET/CT显像阳性患者中，有3例经病理检查证实为甲状腺癌转移；¹⁸F-FDG PET/CT显像阳性病灶与阴性病灶的长短径差异无统计学意义。结论 接受甲状腺全切和大剂量¹³¹I清除残留甲状腺组织治疗后的DTC患者术后随访血清Tg及¹³¹I-WBS均为阴性时，¹⁸F-FDG PET/CT显像可显示可疑的阳性病灶，有助于发现复发和转移病灶。

Objective To investigate the application of ¹⁸F-FDG PET/CT in detection of tumor  recurrence and metastasis among patients with negative findings in serum thyroglobulin (Tg) measurement and ¹³¹I-whole body scan (¹³¹I-WBS) after total thyroidectomy and 131I ablation of the remaining thyroid tissues for differentiated thyroid carcinoma (DTC). Methods Forty-one patients with DTC underwent total thyroidectomy and 131I ablation of the remaining thyroid tissues, and were followed up with serum Tg measurement, ¹³¹I-WBS, neck ultrasound, chest CT and whole body ¹⁸F-FDG PET/CT. Results All these 41 patients had negative findings in serum Tg measurement and ¹³¹I-WBS, while abnormal lesions were detected by neck ultrasound or chest CT. Twenty-three patients had positive findings in ¹⁸F-FDG PET/CT, 3 of whom were confirmed as thyroid carcinoma metastases by pathological examinations. There was no significant difference between the size of ¹⁸F-FDG PET/CT positive lesions and that of ¹⁸F-FDG PET/CT negative lesions. Conclusion ¹⁸F-FDG PET/CT may demonstrate suspicious positive lesions in patients with negative findings in serum Tg measurement and ¹³¹I-WBS after total thyroidectomy and ¹³¹I ablation of the remaining thyroid tissues for DTC, which may help in the detection of tumor recurrence and metastasis.