V12-01: Computational fluid dynamics simulations of male voiding: a novel method using real-time magnetic re

V12-01: Computational fluid dynamics simulations of male voiding: a novel method using real-time magnetic resonance image



To study the mechanism of the urine stream during micturition, we developed a noninvasive magnetic resonance image (MRI) protocol that simulates computational fluid dynamic (CFD) of male voiding.


MRI uroflowgraphic assessment was done during urinary voiding in the lateral position. To visualize the entire pelvis and urethra, a sagittal plane image was obtained such that a line connecting the coccyx and pubic symphysis could be observed during micturition. In addition, 2 more images were collected, bilaterally, 1 cm from the midplane. Three coronal planar imaging, at the midplane including centerline of urethra, and 1cm back side and front side were performed. We were collected the intermitted images until the end of voiding. Using the total 6 planar MRI digital imaging and communications in medicine files, we created a multiple 3D models during voiding. We created 7 models, to span the duration from initiation to terminal voiding. Those multiple intermitted models were converted to a serial dynamic model with special software. Pressure and velocity of the 3 different sites in the bladder simulation model were measured by CFD software. Those CFD results were compared with simple model. This simple model was artificially made in a shape resembling a balloon.


Deformation of the bladder neck appeared to be very complicated. CFD result showed real-time changes in stream, pressure, and velocity (fig. 1). The intravesical pressure differed depending on the measuring site (fig. 2). The actual 3D dynamic model created from MRI data showed highly intricate urine flow compare with simple model.


A dynamic 3D model can be created from MRI data using CAD software. This new method is noninvasive and involves no radiation exposure. This dynamic model can be used for computational fluid dynamics simulation. This new method is useful in improving our understanding of the mechanism of urinary voiding.

Funding: JSPS KAKENHI Grant-in-Aid for Exploratory Research Number JP 15K15587