In vivo patient measurements of bladder elasticity using Ultrasound Bladder Vibrometry (UBV)

A healthy compliant bladder is capable of storing increasing volumes of urine at low pressures. The loss of bladder compliance is associated with various diseases. The urodynamic studies (UDS), the current clinical gold standard for measuring bladder compliance, requires catheterization and measuring intra-bladder pressure as a function of filling volumes. Ultrasound Bladder Vibrometry (UBV) is a noninvasive technique that uses focused ultrasound radiation force to excite Lamb waves in the bladder wall and pulse-echo techniques to track the wave motion in tissue. Cross-spectral analysis is used to calculate the wave velocity, which is directly related to the elastic properties of the bladder wall. In this study, we compare the measurements of changes in bladder elasticity as a function of bladder pressure and volume obtained using UBV and the pressure-volume measurements obtained using UDS. UBV and UDS of an excised porcine bladder are presented. Comparative studies in neurogenic and healthy patient bladders are also summarized.