Ultrasound-guided implantation of radioactive 125 I seed in radioiodine refractory differentiated thyroid carcinoma

Background Treatment for radioiodine refractory differentiated thyroid carcinoma (RR-DTC) is challenging. The purpose of this study was to assess the efficacy and safety of ultrasound-guided implantation of radioactive 125 I-seed in radioiodine refractory differentiated thyroid carcinoma. Methods Thirty-six cervical metastatic lymph nodes (CMLNs) diagnosed with RR-DTC from 18 patients were enrolled in this retrospective study. US and contrast-enhanced ultrasound (CEUS) examinations were performed before implantation. Follow-up comprised US, CEUS, thyroglobulin (Tg) level and routine hematology at 1–3, 6, 9 and 12 months and every 6 months thereafter. The volumes of the nodules were compared before implantation and at each follow-up point. The volume reduction rate (VRR) of nodules was also recorded. Results The median volume of the nodules was 523 mm 3 (148, 2010mm 3 ) initially, which decreased significantly to 53mm 3 (0, 286mm 3 ) ( P < 0.01) at the follow-up point of 24 months with a median VRR as 95% (86,100%). During the follow-up period (the range was 24–50 months), 25 (69%) nodules had VRR greater than 90%, of which 12 (33%) nodules had VVR ≈ 100% with unclear structures and only 125 I seed images were visible in the US. At the last follow-up visit, the serum Tg level decreased from 57.0 (8.6, 114.8) ng/ml to 4.9 (0.7, 50.3) ng/ml, ( P < 0.01). Conclusion US-guided 125 I seed implantation is safety and efficacy in treating RR- DTC. It could be an effective supplement for the comprehensive treatment of thyroid cancer.