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. 2020 Nov 19;15(11):e0238404.
doi: 10.1371/journal.pone.0238404. eCollection 2020.

A pilot study of bladder voiding with real-time MRI and computational fluid dynamics

Ryan Pewowaruk  1 , David Rutkowski  2   3 , Diego Hernando  3   4 , Bunmi B Kumapayi  5 , Wade Bushman  5 , Alejandro Roldán-Alzate  1   3   6
Affiliations

A pilot study of bladder voiding with real-time MRI and computational fluid dynamics

Ryan Pewowaruk et al. PLoS One. .

Abstract

Lower urinary track symptoms (LUTS) affect many older adults. Multi-channel urodynamic studies provide information about bladder pressure and urinary flow but offer little insight into changes in bladder anatomy and detrusor muscle function. Here we present a novel method for real time MRI during bladder voiding. This was performed in a small cohort of healthy men and men with benign prostatic hyperplasia and lower urinary tract symptoms (BPH/LUTS) to demonstrate proof of principle; The MRI urodynamic protocol was successfully implemented, and bladder wall displacement and urine flow dynamics were calculated. Displacement analysis on healthy controls showed the greatest bladder wall displacement in the dome of the bladder while men with BPH/LUTS exhibited decreased and asymmetric bladder wall motion. Computational fluid dynamics of voiding showed men with BPH/LUTS had larger recirculation regions in the bladder. This study demonstrates the feasibility of performing MRI voiding studies and their potential to provide new insight into lower urinary tract function in health and disease.

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Conflict of interest statement

The authors have read the journal’s policy and have the following potential competing interests: the authors received CONVERGE licenses through a partnership between Convergent Science Inc. and the University of Wisconsin – Madison. This does not alter our adherence to PLOS ONE policies on sharing data and materials. There are no patents, products in development or marketed products associated with this research to declare.

Figures

Fig 1
Fig 1. MRI protocol.
Fig 2
Fig 2. Schematic of the bladder wall divided into anterior-posterior, dome-base, and left-right regions for regional displacement and asymmetry analysis.
Different colors represent different regions (anterior–aqua, posterior–yellow, dome–navy blue, base–royal blue, left–red, right–not shown).
Fig 3
Fig 3. Real time imaging of voiding in a 66-year-old healthy volunteer.
The curve shows the bladder emptying with respect to time following a sigmoidal behavior. 2D mid sagittal plane images show the bladder deformation at four different time points during the voiding event. Similarly, three-dimensional (3D) maps show bladder contraction (wall displacement) estimated from computational interpolation between pre and post void MRI at four different time points during voiding.
Fig 4
Fig 4. Top row: Pre- and post-voiding bladder anatomies for each subject.
Middle row: Bladder wall displacement maps (in mm) for each subject. Note that the legend scale is much smaller for the men with BPH/LUTS. Bottom row: Box plots showing regional displacement behavior for each subject (C: Control; P: Patient).
Fig 5
Fig 5. Probability density functions of bladder wall displacement show the control subjects bladder move much more during voiding.
Additionally, the men with BPH/LUTS exhibit significant left-right asymmetry that was not observed in the control subjects.
Fig 6
Fig 6. CFD results showing velocity contours and streamlines on a sagittal plane at the center of the bladder for each subject.
Time points are displayed both near the initiation and termination voiding.
Fig 7
Fig 7. Bladder vorticity was lower for the men with BPH/LUTS due to their lower flowrates and urine velocities.
After making vorticity dimensionless (a normalization to account for different flow rates between subjects), vorticity was similar for both groups.
See this image and copyright information in PMC

Comment in

  • Benign Prostatic Hyperplasia.
    Kaplan SA. Kaplan SA. J Urol. 2021 Sep;206(3):745-747. doi: 10.1097/JU.0000000000001919. Epub 2021 Jun 17. J Urol. 2021. PMID: 34134522 No abstract available.

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