Quantifying whole bladder biomechanics using the novel pentaplanar reflected image macroscopy system

Area of Science:

• Biomedical Engineering
• Urology
• Biophysics

Background:

• Bladder compliance is crucial for urinary storage and voiding.
• Current clinical methods for bladder compliance lack insight into wall structure and mechanics.
• Lower urinary tract dysfunction is often associated with altered bladder wall biomechanical properties.

Purpose of the Study:

• To develop a novel ex vivo imaging method for real-time measurement of bladder wall stress and stretch.
• To accurately calculate bladder wall biomechanics based on material properties rather than pressure-volume changes.
• To provide a more insightful characterization of bladder wall mechanics during filling.

Main Methods:

• Developed Pentaplanar Reflected Image Macroscopy (PRIM) for ex vivo bladder imaging.
• Simultaneously recorded intravesical pressure, infused volume, and multi-planar bladder images.
• Measured wall thickness and volume to calculate stress and stretch during bladder filling.

Main Results:

• Demonstrated nonlinear increases in bladder wall stress with increasing stretch, particularly above 15 mmHg intravesical pressure.
• Showed that bladder wall mechanical properties remain consistent across bladders of varying capacities.
• Quantified bladder wall tension, stress, and stretch, defining biomechanics via material properties.

Conclusions:

• PRIM enables accurate, real-time measurement of bladder wall biomechanics.
• This method offers superior insight into bladder wall material properties compared to traditional compliance calculations.
• PRIM is valuable for studying bladder remodeling in conditions like diabetes and spinal cord injury.