Real-time tissue elastography in the evaluation of uterine fibroids with different echo intensity following radio-frequency ablation

Abstract

Objective 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). Methods 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. Results (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 0.05). (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 0.05). (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 0.05). Conclusions 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. Key words: Leiomyoma; Radio-frequency ablation; Elasticity imaging techniques