Transvaginal shear wave elastography for measuring uterine myometrial and leiomyoma stiffness: a protocol pilot study

Recent studies suggest that the stiffness of uterine leiomyomas may be related to their growth and behavior. Shear wave elastography (SWE), 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 establish a standardized protocol for transvaginal SWE to measure uterine myometrial and leiomyoma stiffness and assess the reproducibility and reliability of SWE measurements. We also assessed myometrial vs. leiomyoma stiffness, compared myometrial stiffness in participants with and without leiomyomas, and assessed menstrual phase effects on stiffness values.

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

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

Tissue type (myometrium/leiomyoma), leiomyoma status (presence/absence of leiomyomas), and menstrual phase (follicular/luteal).

Interrater and test-retest reliability of SWE measurements. Myometrial and leiomyoma shear wave values.

We successfully designed a streamlined protocol for obtaining SWE measurements in participants with and without leiomyomas. Fifty-one myometrial and 38 leiomyoma stiffness values measured by 2 independent raters achieved excellent interrater reliability: the intraclass correlation coefficients between the 2 raters were 0.990 and 0.994, respectively. Fifty myometrial and 42 leiomyoma stiffness measurements calculated by a single rater at 2 time points at least 90 days apart achieved excellent test-retest reliability: intraclass correlation coefficients of 0.992 and 0.995. The median stiffness values for leiomyomas were significantly higher than those for the surrounding myometrium (48.1 [interquartile range, 39.7-59.5] vs. 31.6 [interquartile range, 22.9-46.9] kPa). There was no significant change in myometrial or leiomyoma median stiffness values between the menstrual phases.

Transvaginal ultrasound SWE showed excellent reproducibility and reliability in measuring myometrial and leiomyoma stiffness. Leiomyoma stiffness was significantly higher than that for the surrounding myometrium. Together, these findings support SWE's potential clinical utility in leiomyoma management.