Catheter-Free Bladder Pressure Measurement With Contrast-Enhanced Ultrasound

One of the major challenges in urodynamic testing is the presence of an indwelling urethral catheter during voiding pressure evaluation. The space-occupying property of the catheter results in non-physiological conditions, which in turn, can cause misdiagnosis. In this study we hypothesize that ultrasound-based technique known as subharmonic-aided pressure estimation (SHAPE) can measure pressure in a bladder phantom. SHAPE is based on the principle that subharmonic emission of ultrasound contrast agents decreases linearly with increasing ambient pressure.

Schematic of the benchtop experimental setup to investigate SHAPE efficacy in measuring bladder phantom pressure.

Ultrasound image of microbubbles inside the bladder phantom

Correlation between SHAPE and cystometrogram pressure readings

An example of correlation between benchtop bladder pressure (dashed-dotted line; left vertical axis) and subharmonic signal scattered by microbubbles (red dashed line; right vertical axis) during a post-filling event. The process used in calculating change in ambient pressure and subharmonic signal is also illustrated; the baseline signal (blue solid lines) is subtracted from peak values (solid and hollow circles).

Related Publications

[1] K. Kalayeh, J. B. Fowlkes, A. Chen, S. Yeras, M. L. Fabiilli, J. Claflin, S. Daignault-Newton, W. W. Schultz and B. S. Sack, “Pressure Measurement in a Bladder Phantom Using Contrast-Enhanced Ultrasonography-A Path to a Catheter-Free Voiding Cystometrogram.,” Invest. Radiol., vol. 58, no. 3, pp. 181-189, 2023. https://www.ncbi.nlm.nih.gov/pubmed/36070543

[2] K. Kalayeh, J. B. Fowlkes, J. Claflin, M. L. Fabiilli, W. W. Schultz and B. S. Sack, “Ultrasound Contrast Stability for Urinary Bladder Pressure Measurement.,” Ultrasound Med Biol, vol. 49, no. 1, pp. 136-151, 2023. https://www.ncbi.nlm.nih.gov/pubmed/36244919