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Urine Flow Dynamics Through Prostatic Urethra With Tubular Organ Modeling Using Endoscopic Imagery

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Voiding dysfunction is common in the aged male population. However, the obstruction mechanism in the lower urinary tract and critical points for obstruction remains uncertain. The aim of this paper was to develop a system to investigate the relationship between voiding dysfunction and alteration of the shape of the prostatic urethra by processing endoscopic video images of the urethra and analyzing the fluid dynamics of the urine stream. A panoramic image of the prostatic urethra was generated from cystourethroscopic video images. A virtual 3-D model of the urethra was constructed using the luminance values in the image. Fluid dynamics using the constructed model was then calculated assuming a static urethra and maximum urine flow rate. Cystourethroscopic videos from 11 patients with benign prostatic hyperplasia were recorded around administration of an alpha-1 adrenoceptor antagonist. The calculated pressure loss through the prostatic urethra in each model corresponded to the prostatic volume, and the improvements of the pressure loss after treatment correlated to the conventional clinical indices. As shown by the proposed method, the shape of the prostatic urethra affects the transporting urine fluid energy, and this paper implies a possible method for detecting critical lesions responsible for voiding dysfunction. The proposed method provides critical information about deformation of the prostatic urethra on voiding function. Detailed differences in the various types of relaxants for the lower urinary tract could be estimated.
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See complete bios of the authors in the full version of this article.
T IshiiT Ishii
Mr. Ishii has been a Research Fellow of the Japan Society for the Promotion of Science since 2012. His research interests include image processing for endoscopic images, in particular, spatial recognition of body cavity for medical staffs and fluid dynamics analysis in the lower urinary tract.

Y KambaraT Ishii
Mr. Kambara has received B.Sc. and M.Sc. degrees in engineering from Chiba University, Chiba, Japan, in 2011 and 2013, respectively. His research topics are shape modeling of the urinary tract and urine flow analysis for voiding dysfunction.

T YamanishiT Yamanishi
Prof. Yamanishi is a Professor of Urology at Dokkyo Medical University. He is also a Boarding Member of the Japanese Urological Association, Japanese Neurogenic Bladder Society, Japan Medical Association of Spinal Cord Lesion, and Japanese Association of Enuresis, and also a member of the International Continence Society, European Association of Urology, American Urological Association, International Spinal Cord Society, and International Urogynecological Association.

Y NayaY Naya
Dr. Naya is a top-ranked surgeon in Japan, particularly in the urological field. His research interests are laparoscopic surgery for the urogenital organs and endourology, in particular, establishment of focal therapy in the urological field.

T IgarashiT Igarashi
Dr. Igarashi is a Professor at the Research Center for Frontier Medical Engineering, since 2003. His research interests are endoscopic image processing and macroscopic ow dynamics in the body cavity, in particular, the novel surgical system carried out under water.

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