Transvaginal Shear Wave Elastography for Measuring Uterine Myometrial and Leiomyoma Stiffness: a Protocol Pilot Study.

Objective: Recent studies suggest that the stiffness of uterine leiomyomas may be related to their growth and behavior. Shear wave elastography, a quantitative method of measuring tissue stiffness, has been increasingly studied for use in gynecologic conditions. However, no protocols have been proposed for its use in this clinical setting. This study aimed to 1) establish a standardized protocol for transvaginal shear wave elastography to measure uterine myometrial and leiomyoma stiffness and 2) assess the reproducibility and reliability of shear wave elastography measurements. We also assessed myometrial versus leiomyoma stiffness, compared myometrial stiffness in participants with and without leiomyomas, and assessed menstrual phase effects on stiffness values.

Design: Transvaginal SWE ultrasound measurements of myometrial and leiomyoma stiffness were obtained. All transvaginal SWE exams were performed by an individual sonographer. Independent raters calculated stiffness measurements. Myometrial and leiomyoma stiffness were compared across menstrual phases.

Subjects: Twenty-seven premenopausal women, 16 with leiomyomas and 11 without were enrolled. Seventeen participants completed exams during multiple menstrual phases.

Exposure(s): 1. Tissue type (Myometrium/Leiomyoma) 2. Leiomyoma status (Presence/Absence of leiomyomas) 3. Menstrual phase (Follicular/Luteal) MAIN OUTCOME MEASURES: Inter-rater and test-retest reliability of shear wave elastography measurements. Myometrial and leiomyoma shear wave values.

Results: We successfully designed a streamlined protocol for obtaining shear wave elastography measurements in participants with and without leiomyomas. Fifty-one myometrial and 38 leiomyoma stiffness values measured by two independent raters achieved excellent inter-rater reliability: the intraclass correlation coefficients (ICC) between the two raters were 0.990 (p<0.001) and 0.994 (p<0.001), respectively. Fifty myometrial and 42 leiomyoma stiffness measurements calculated by a single rater at two time points at least 90 days apart, achieved excellent test-retest reliability: ICC=0.992, p<0.001; ICC=0.995, p<0.001. Median stiffness values for leiomyomas were significantly higher than the surrounding myometrium (48.1 (IQR 39.7-59.5) versus 31.6 (IQR 22.9-46.9) kPa, p<0.001). There was no significant change in myometrial or leiomyoma median stiffness values between the menstrual phases.

Conclusion: Transvaginal ultrasound shear wave elastography showed excellent reproducibility and reliability in measuring myometrial and leiomyoma stiffness. Leiomyoma stiffness was significantly higher compared to the surrounding myometrium. Together, these findings support shear wave elastography's potential clinical utility in leiomyoma management.