To investigate the value of real-time elastography (RTE) in evaluating the characteristics and elasticity index (E-index) changes at different echo level of uterine fibroids before and after radiofrequency ablation (RFA).

A total of 43 patients (with 55 lesions) accepted RFA under ultrasound guidance in the Fourth Affiliated Hospital of Harbin Medical University from September 2013 to January 2015. All lesions were confirmed to have no perfusion through ultrasonography 1 h after RFA. The diameter of lesions ranging from 1.0 cm to 3.0 cm (with an average of 1.9±1.2 cm). Preoperative lesions were classified into 3 groups for comparison based on ultrasonic echo type, group A: hypo echo (n=30); group B: hyper echo (n=12); and group C: mixed echo (n=12). Measured elasticity index E-index and internal uniformity (△E) were analyzed. Comparisons of E value and △E value were performed with repeated measures. RTE images features using χ² test of Fisher inspection comparison at the same time differences between groups.

(1) Before RFA, RTE images showed blue alternating with green with green being dominated accounting for 70% (21/30). 50% of RTE images in group B were completely covered in blue (6/12), while group C exhibited 53.9% blue alternating with green with blue being dominated (7/13). There were statistically significant characteristics of RTE images among 3 groups (P<0.01). 1 h after RFA, 74.5% lesions exhibited with blue being dominated (41/55). However, 83.6% (41/55) exhibited with blue 3 months after RFA. The difference in characteristics of RTE among 3 groups displayed no statistical significance (P>0.05). (2) The comparison of E-index revealed that before RFA, the E value was the lowest in the group A and the highest in the group B, while the group C was between them. There was significant difference between group A and B (F=19.25, P<0.01). E-index elevated in all the three groups and significant differences were found 1 h, 3 month after RFA in comparison with that before RFA in the group A (F=386.75, 294.68, both P<0.01). In addition, significant differences were also found 1 h, 3 month after RFA in comparison with the treatment in the group B (F=29.98, 45.88, both P<0.01). As for the group C, there were significant differences in E-index 1 h, 3 month after RFA compared with before RFA (F=120.29, 139.64, both P<0.01). 3 months after RFA, E-index further elevated in the three groups and no significant inter-group difference was found at the same time points (P> 0.05). (3)Before RFA, the △E value was lower in group A and group B, while higher in the group C, group C presenting significant difference from group A and B (F=484.68, 344.15, both P<0.01). At 1 h after RFA , △E value was higher in group A and group C, while lower in group B, with group B showing significant difference from the low and mixed echo groups (F=53.58, 94.79, both P<0.01). Significant difference was observed 1 h after surgery compared to before RFA in group A (F=154.35, P<0.01). Significant difference was also found 1 h after RFA compared to 3 month after RFA in group A (F=266.85, P<0.01). As for group C, there were also significant differences in △E-index before treatment and 1 h after RFA compared with 3 month after RFA (F=103.24, 76.53, both P<0.01). At 3 months after RFA, △E-index decreased in all three groups. No significant inter-group difference was found at the same time points (all P>0.05).

RTE characteristics and the elasticity index are distinctly different among uterine fibroid at various echo intensities. RTE contributes to judging changes in hardness before and after RFA. The application of RTE for quantitative comparison of lesion hardness and uniformity can be served as the foundation for evaluating therapeutic effects of RFA.