Significance of 131I whole body scan combined with serum thyroglobulin in the follow-up of differentiated hyroid cancer after thyroid ablation

Abstract

Objective To evaluate the clinical value of 131I whole body scans with that of serum thyroglobulin (Tg)determination for the follow-up of differentiated thyroid carcinoma(DTC)receiving postoperative 131I therapy.Methods There were 153 patients with differentiated thyroid cancer receiving postoperative 131I therapy for more than one time at the dose of 1.85-9.25 GBq.Serum Tg levels were measured before 131I treatment and 131I whole body scans were performed 5 days after treatment.Results Among the 153 patients who underwent 131I therapy,serum Tg levels and 131I-whole body scans were both abnormal in 85 patients (55.6％).Both examinations were negative in 21 patients (13.7％).In the 19 patients with abnormal 131I whole body scans only,image study with means of 18F-FDG,SPECT,CT,ultrasonic or whole body bone scan revealed lesions in 13 patients; while in the 28 patients with abnormal Tg levels only,image study with the above means revealed lesions in 25 patients.The sensitivity of Tg positiveness and 131I whole body scans positiveness were 89％ (110/123) and 79.6％ (98/123) respectively,and the specificity were 90％ (27/30)and 80％ (24/30)respectively.Conclusions Routine serum Tg measurement and 131I whole body scans in patients with DTC with 131I radiotherapy after thyroidectomy is essential.It is of greatly clinical value in early detecting metastases,optimizing the 131I treatment protocol and evaluating the curative effect. Key words: Thyroid neoplasms; Thyroglobulin; Iodine radioisotopes