In this study, we retrospectively analyzed 214 patients who underwent ultrasound - guided microwave ablation. After 10.12 ± 2.78 months of follow-up, the volume reduction ratio(VRR) of benign thyroid nodules was up to 85.60%. Univariate analysis showed that there was a statistical difference between the initial volume of nodules and the effect of microwave ablation. Logistic regression analysis showed that microwave ablation had a good effect on the initial volume of nodules less than or equal to 10 ml. Furthermore, the serum levels of triiodide thyroid hormone (T3), thyroxine (T4) and thyrotropin (TSH) were all within the normal range, indicating that microwave ablation would not impair thyroid function.
The therapeutic effect of microwave ablation has been proved clinically at home and abroad. It has a good therapeutic effect on benign thyroid nodules. Numerous studies have shown that the volume reduction ratio after microwave ablation can reach 24.0–51%, 54.8–75.1%, 68.7–85.2%, 75.8–96.4% respectively after 1, 3, 6 and 12 months.[1, 5, 11–14] Our study showed similar outcomes.
Our results are consistent with those reported by Liu YJ, Yue W, Wu W et al.[13, 15, 16], none of the patients treated with microwave ablation had serious complications. Only one case of intrathyroid hemorrhage and postoperative hoarseness occurred in our study, but all recovered 2 months after the MWA. Hu et al.[12] found that 2.3% of the sound changes in the study followed microwave ablation, but all recovered within two weeks. Therefore, it can be seen that microwave ablation(MWA)for benign thyroid class has the characteristics of fewer complications and easier recovery.
In our study, Logistic regression analysis showed that the initial volume of nodules, especially small nodules (volume < 10 ml), was a risk factor for the effect of microwave ablation. Cesareo R et al.[17]obtained similar results in their study, suggesting that ablation can effectively reduce benign thyroid nodules, especially small ones. Lee GM et al.[10] found that ablation was more effective in the treatment of small nodules with a volume less than 4 ml.(P = 0.030)
Heck K et al.[18] proposed that the serum levels of triiodothyroid hormone (T3), thyroxine (T4), thyrotrophin (TSH), thyroglobulin (Tg), anti-TG, thyrotrophin receptor (TRAb), and thyroid peroxidase (anti-TPO) showed no significant changes after the microwave ablation and the follow-up of half a year. Erturk MS et al.[19] pointed out that the effect of MWA on thyroid function had no significant difference at 6 months, but the effect was significant at 24 hours. In our study, we reached the same conclusion that the serum levels of triiodide thyroid hormone (T3), thyroxine (T4) and thyrotropin (TSH) after microwave ablation were all within the normal level and decreased compared with that before surgery. Therefore, we have reason to believe that microwave ablation has a good effect and has no effect on thyroid function.
This study still has some limitations. First, this was a retrospective study, with no control group. Second, the follow-up time in this study was not long enough so that the volume reduction ratio reached a plateau value. Third, symptom scores and cosmetic scores were not used for quantitative evaluation. Therefore, long-term, quantitative and prospective studies are needed to further verify the conclusions in the future.