Therapeutic designing for urethral obstruction by virtual urethra and flow dynamics simulation

Abstract

Introduction: Transurethral surgery is widely accepted as standard therapy for male urethral obstruction. The present study was undertaken to identify and select lesions to be managed by processing endoscopic images of the urethra for assisting less invasive therapy in patients with voiding dysfunction. Material and methods: Cystourethroscopic video files of 25 patients with lower urinary tract symptoms were recorded before and after administration of alpha-1 adrenoceptor antagonists. Each video frame was restored and tagged with information indicating the position in the panoramic image of the urethra. A three-dimensional virtual urethra was created to indicate critical lesions for voiding dysfunction, together with fluid dynamics simulation of urine flow. Results: The urine stream was depicted in the virtual urethras in 19 patients. Before therapy, 17 patients showed vortex formation that was diminished after therapy in nine patients with a significant relationship in improvement of relative energy loss of flow (p=0.025). The narrowing points proximal to the vortex, candidate of lesions, were identified in the panoramic image and linked to the endoscopic image. Discussion: Therapeutic designing for endoscopic management was possible in patients with voiding dysfunction based on computational fluid dynamics, and would be promising as “focal” therapy for aging males.

Key words:

• 3D virtual endoscopy
• computational fluid dynamics
• minimally invasive procedure
• endoscopy
• voiding dysfunction

Acknowledgement

The research is sponsored by National grant of Ministry of Culture, Education and Sports in Japan (No.23659753).We thank Drs. Sazuka T from Department of Urology, Chiba University, Dr. Mikami K. from Department of Urology, Saiseikai Narashino Hospital, for their efforts to collect patients’ data, and to Mr. Kambara Y., Graduate School Engineering, Chiba University, for supporting to analyze hydraulic calculation.

Declaration of interest: Corresponding author (T.I.) accepted donation from Asahi Kasei Corp., Chiyoda-ku, Tokyo, Japan and Astellas Pharma Inc., Chuo-ku, Tokyo, Japan.