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 post-operative ¹³¹I therapy.

Methods There were 153 patients with differentiated thyroid cancer receiving post-operative 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.