Quantitative elasticity measurement of urinary bladder wall using laser-induced surface acoustic waves

Abstract

Abstract:The maintenance of urinary bladder elasticity is essential to its functions, including the storage and voiding phases of the micturition cycle. The bladder stiffness can be changed by various pathophysiological conditions. Quantitative measurement of bladder elasticity is an essential step toward understanding various urinary bladder disease processes and improving patient care. As a nondestructive, and noncontact method, laserinduced surface acoustic waves (SAWs) can accurately characterize the elastic properties of different layers of organs such as the urinary bladder. This initial investigation evaluates the feasibility of a noncontact, all-optical method of generating and measuring the elasticity of the urinary bladder. Quantitative elasticity measurements of ex vivo porcine urinary bladder were made using the laser-induced SAW technique. A pulsed laser was used to excite SAWs that propagated on the bladder wall surface. A dedicated phase-sensitive optical coherence tomography (PhS-OCT) system remotely recorded the SAWs, from which the elasticity properties of different layers of the bladder were estimated. During the experiments, series of measurements were performed under five precisely controlled bladder volumes using water to estimate changes in the elasticity in relation to various urinary bladder contents. The results, validated by optical coherence elastography, show that the laser-induced SAW technique combined with PhS-OCT can be a feasible method of quantitative estimation of biomechanical properties. 1768-1778 (1999). 3. T. Watanabe, S. Omata, J. Z. Lee, and C. E. Constantinou, "Comparative analysis of bladder wall compliance based on cystometry and biosensor measurements during the micturition cycle of the rat," Neurourol. Urodyn. 16(6), 567-581 (1997). 4. A. Elbadawi, S. V. Yalla, and N. M. Resnick, "Structural basis of geriatric voiding dysfunction. IV. Bladder outlet obstruction," J. Urol. 150(5 Pt 2), 1681-1695 (1993). 5. L. M. Liao and W. Schaefer, "Cross-sectional and longitudinal studies on interaction between bladder compliance and outflow obstruction in men with benign prostatic hyperplasia," Asian J. Androl. 9(1), 51-56 (2007 418-426 (2012). 10. K. Sabanathan, H. M. Duffin, and C. M. Castleden, "Urinary tract infection after cystometry," Age Ageing 14(5), 291-295 (1985). 11. N. N. Bhatia and A. Bergman, "Cystometry: unstable bladder and urinary tract infection," Br. J. Urol. 58(2), 134-137 (1986) 21-29 (1994). 54. F. F. Chai and T. T. Wu, "Determination of anisotropic elastic constants using laser-generated surface waves," J. ©2014 Optical Society of AmericaAcoust. Soc. Am. 95(6), 3232-3241 (1994

The dynamic deformation of a layered viscoelastic medium under surface excitation

“…Such results are in agreement with the experimental data obtained for surface wave propagation by the other groups (Li et al, 2012b, Li et al, 2014). Therefore, the depth-dependence of the mechanical parameters could be potentially resolved by relying on the spectral analysis concept.…”

“…The radiation force can be generated not only inside the tissue but also at the tissue surface or at the tissue boundaries where there is a significant difference in the acoustic impedance. Tissue excitation and surface deformation measurements have been used in elastography of skin (Li et al, 2012a, Li et al, 2012b, Coutts et al, 2006, Kirkpatrick et al, 2006), cornea (Tanter et al, 2009, Twa et al, 2014), crystalline lens (Wang et al, 2013, Manapuram et al, 2011, Wu et al, 2015), bladder wall (Li et al, 2014, Nenadic et al, 2013) and other potential applications (Sarvazyan, 2010). However, in all of these applications, the depth inhomogeneity of the tissue plays an important role in its mechanical response.…”

Design and Anchorage Dependence of Shape Memory Alloy Actuators on Enhanced Voiding of a Bladder

“…The balloon voiding in petri dish under 4 V application for 25 s is shown in Movie S3 (Supporting Information). Young's Modulus of the bladder muscle is at least two orders of magnitude smaller than that of the rubber balloon, [38] therefore a higher value of ΔV/V was not unexpected.…”

A 3D Printed Implantable Device for Voiding the Bladder Using Shape Memory Alloy (SMA) Actuators

“…This increased the voided amount to a Δ V / V of 7.7%. For comparison, the Young's modulus of the bladder muscle is at least two orders of magnitude smaller than that of the rubber balloon,46 thus a higher value of Δ V / V was not unexpected. However, the urethral resistance can affect the value of Δ V / V 1.…”