Introduction: The ability to identify and quantitate peri-urethral fibrosis is limited prior to urethral stricture surgery. Shear wave elastography (SWE) is a quantitative and reproducible method to measure a tissue’s elastic properties. We examined the utility of SWE for the evaluation of corpus spongiosum elasticity pre- and post-urethral stricture surgery.
Methods: Patients with a single, bulbar urethral stricture diagnosed on preoperative cystoscopy or retrograde urethrogram, who elected to undergo surgical repair provided informed consent to participate in this ongoing, IRB-approved study from October 2018 to September 2019. SWE imaging was performed under anesthesia prior to open surgical repair using an Aplio i800 scanner (Canon Medical Systems, Tustin, CA) and an i8CX1 transducer with the system’s proprietary SWE package. Upon acquisition of stricture images, 4 regions of interest (ROI) were placed on the corpus spongiosum – 2 on the stricture, 2 on healthy tissue. Tissue elasticity (in kPa) was averaged across the ROIs. SWE and the associated data analysis were then repeated for each patient during their 3-month post-operative appointment. Pre- to post-procedure results were compared using paired student’s t-tests.
Results: Twelve men (mean age 57.1±18.1 years and BMI 29.2±6.8 kg/m2) have been enrolled. Nine (75%) patients had previously undergone a median of 2 stricture dilation procedures. Seven (58%) patients have undergone post-operative follow-up imaging, 6 of which revealed no evidence of stricture recurrence. One patient (8%) did not undergo urethroplasty as his stricture was passively dilated on cystoscopy. Mean elasticity among the strictured urethra was lower before surgery (27.9±5.8 kPa) compared to after surgery (36.8±4.2 kPa) (n=7, p=0.56). Mean elasticity of the strictured portion was lower (27.9±5.8 kPa) than that of the healthy urethra (29.9±4.3 kPa) before surgery (n=12, p=0.19) and after surgery (36.8±4.2 vs. 37.5±3.4 kPa, n=7, p=0.32).
Conclusions: SWE may help to assess peri-urethral fibrosis in the initial characterization and post-operative follow-up of urethral stricture disease. Further studies assessing the utility of SWE and optimizing the protocol should be performed in larger cohorts. Source of
Funding: Material Support Grant from Bracco Diagnostics, Provost’s Pilot Clinical Research Award from Thomas Jefferson University
