Factors influencing the outcome from ultrasonography-guided fine-needle aspiration of benign thyroid cysts and partially cystic thyroid nodules: A multicenter study

Abstract

Purpose: The effect of ultrasonography (US)-guided fine-needle aspiration (US-FNA) for the collapse of benign cystic thyroid nodules is still unclear. This study aimed to assess the positive response rate following US-FNA of the cystic component of thyroid cysts and of partially cystic thyroid nodules (PCTNs), and to evaluate the factors influencing the outcome. Methods: From June to December 2013, seven radiologists at seven institutions prospectively performed US-FNA on 320 cystic thyroid nodules in 320 patients. Among them, 179 underwent at least one follow-up US examination following US-FNA of the cystic component at each institution by the same radiologist. A variety of factors, including US features of cystic thyroid nodules, the characteristics of the aspirates, and the follow-up US findings, were analyzed. Results: Of 179 cystic thyroid nodules, there were 53 thyroid cysts and 126 PCTNs. Of 179 cystic thyroid nodules, no malignancies were detected. On follow-up US, the mean size reduction rate of the cystic component was 31.9%, and 102 out of 179 thyroid nodules (57.0%) were assigned to the response group. On univariate analysis, the degree of aspiration and time interval between US-FNA and the final follow-up US showed the significant differences between the response and no response groups. On multivariate analysis, the only factor that influenced the outcome was the nodule type. The cystic component’s positive response rate after simple aspiration was higher in the thyroid cysts than in the PCTNs. Conclusions: US-FNA may be effective at collapsing the cystic components of benign thyroid cysts and PCTNs.