A Preliminary Study on Quantitative Quality Measurements of the Urethral Rhabdosphincter Muscle by Supersonic Shear Wave Imaging in Women With Stress Urinary Incontinence

Abstract

ObjectivesTo quantitatively assess the quality of the urethral rhabdosphincter muscle by measuring its shear wave velocity (Vs) and calculating the Young modulus (E) with supersonic shear wave imaging (SSI).MethodsThis was a prospective study of 43 women with SUI and 52 female control participants who underwent a transperineal US examination with SSI. Supersonic shear wave imaging was performed at rest with a linear transducer and a specialized‐preset procedure. The stability and validity of the shear waves were automatically assessed by the SSI procedure. The SSI images were visualized in a color‐coded elastographic image. In the postprocessing analysis, the ventral part of the urethral rhabdosphincter muscle was manually outlined. The mean Vs and the mean E of the muscle were measured by the SSI procedure. The relationship between the mean Vs, mean E, and SUI was evaluated.ResultsThe SSI examination was successfully performed in 40 patients with SUI (93.0%) and 40 female control participants (76.9%). No significant differences between the groups in age, body mass index, and parity were identified. For the SUI and control groups, the mean Vs values were 2.54 and 2.73 m/s, respectively, and the mean E values were was 19.7 and 22.7kPa. Significant correlations were found between SUI and the mean Vs as well as the mean E (Spearman correlation coefficients, –0.41 and –0.43; P < .05).ConclusionsThe mechanical properties of the urethral sphincter can be quantitatively assessed by SSI. The stiffness of the urethral rhabdosphincter muscle was significantly lower in women with SUI.

Association between urethral funneling in stress urinary incontinence and the biological properties of the urethral rhabdosphincter muscle based on shear wave elastography

“…SUI correlates with the loss of closing pressure, which appears to be related to rhabdosphincter muscle mass 18 . The stiffness of the rhabdosphincter increases with increasing urethral sphincter quality 5,19 . In this study, we indirectly evaluated the biological properties of the rhabdosphincter to reflect the urethral closing pressure and rhabdosphincter contractility.…”

“…An advantage of this study is the collection of SWE measurements at the anterior and posterior rhabdosphincter, which is superior to previous studies in which the anterior rhabdosphincter alone was the research object 5 . Unexpectedly, we found that the thickness and stiffness measurements of the anterior rhabdosphincter were generally larger than those of the posterior rhabdosphincter, perhaps because there are significant differences in the closing pressure of the four walls of the urethra, with the anterior urethral wall having the highest closing pressure and the posterior wall having the lowest pressure 20 .…”

“…It is well accepted that urethral hypermobility 2 and intrinsic sphincter deficiency (ISD) 3 are the main pathologic factors of SUI. ISD 4 is a dysfunction of the urethral sphincter closure system involving the urethral rhabdosphincter muscle, smooth muscle, and submucosal vessels; among them, the urethral rhabdosphincter is the essential part providing urethral closure pressure 5 . According to the urethral hanging theory, a “weak sphincter” forces funneling of the proximal urethra 6 .…”

“…Thus, clinicians do not recommend this examination for all patients. At present, shear wave elastography (SWE) has been applied to reasonably evaluate the urethral rhabdosphincter 5 . In our study, SWE combined with transperineal ultrasonography (TPUS) was applied to assess the biological properties of the urethral rhabdosphincter to analyze their associations with urethral funneling, aiming to provide a reference for identifying impaired urethral rhabdosphincter in SUI and its ultrasound appearance.…”

Elastography in the Urological Practice: Urinary and Male Genital Tract, Prostate Excluded—Review

“…Zhao B used supersonic shear wave imaging to compare the stiffness of the striated urinary sphincter in women with stress incontinence. Comparing 40 patients with stress urinary incontinence and 40 healthy subjects with no difference in age, as well as the body mass index and parity between the groups, they observed that the stiffness of the urethral rhabdosphincter muscle was significantly lower in women with stress urinary incontinence (mean values: 2.54 vs. 2.73 m/s; 19.7 vs. 22.7 kPa) [ 90 ].…”