Abstract:

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.

Key words: differentiated thyroid carcinoma, ¹³¹I whole body scan, serum thyroglobulin, ¹⁸F-FDG