| Objective To understand the capacity of shear wave elastography(SWE)in assessing the ablation zone of benign thyroid nodules treated with microwave ablation and to observe the dynamic changes of Young’s modulus before and after treatment.Methods Data of 32 patients with benign thyroid nodules who underwent microwave ablation from September 2018 to August 2020 was included.There were 39 lesions,including 33 cases of nodular goiter and 6 cases of thyroid adenoma.SWE examination including vertical and horizontal sections was performed before ablation and 1,3 and 6 months after ablation.The ablation zone displayed by SWE was compared with that measured by conventional ultrasound and contrast-enhanced ultrasound(CEUS)at different time after treatment.Moreover,the changes of Young’s modulus of the ablation zone were recorded.Results(1)At 1,3 and 6 months after microwave ablation,the average volume of ablation nodules decreased gradually both in nodular goiter and in thyroid adenoma.In the nodular goiter group,the difference between different time before and after treatment was statistically significant(P <0.05).In the thyroid adenoma group,there is a statistically significant difference between 6 months after surgery and before and 1 month after surgery(P < 0.05).Among other time comparisons,there was no statistically significant difference(P>0.05).The comparison between the two groups simultaneously showed no significance(P > 0.05).(2)After ablation,the effective rate of nodules treatment increased gradually,and the difference was statistically significant between 3 and 6months after operation and 1 month after operation(P < 0.05).The reduction rate of nodule volume increased continuously in both groups,and there was no significant difference between the two groups 1 month after operation(P> 0.05).But at 3 and 6 months after operation,there was a significant difference(P < 0.05).(3)At 1 month after operation of nodular goiter,SWE showed that the ablation zone’s length was larger than that measured by conventional ultrasound.There was no significant difference in the ablation zone between SWE and conventional ultrasound at 3 and 6 months after operation.However,the length on SWE was less than that on CEUS at 3 months after operation.In the thyroid adenoma group,the ablation zone on SWE was not significantly different from those on conventional ultrasound and CEUS at various times after operation(P > 0.05).(4)After ablation,the mean(Emean)and maximum(Emax)of Young’s modulus of ablation lesions in the nodular goiter group and thyroid adenoma group both increased at first and then decreased.In the same group,there were statistical difference between different time before and after ablation(P <0.05).Between the two groups,there was no significant difference in Emax values before ablation,1,3 months after operation,and Emean values at 1,3and 6 months after operation(P>0.05).But the Emax values compared at 6months after the operation and the Emean values compared before ablation between the two groups showed a statistical significant difference(P<0.05).Conclusions(1)SWE can identify the hardness difference between the ablation lesion and the surrounding normal thyroid tissue.Moreover,it can accurately evaluate the range of benign thyroid nodules after microwave ablatio,which can be used as a non-invasive way to evaluate the ablation efficacy.During the short-term follow-up period after surgery,the volume reduction rate of ablation nodules measured by SWE and the effective rate of treatment gradually increased.(2)After microwave ablation of benign thyroid nodules,the hardness of ablation lesions measured by SWE was significantly improved compared with that before operation,showing a trend of increasing at first and then decreasing,reaching a peak at 1 month after operation,which wil help clinicians to judge the texture change and absorption of the lesion. |
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