Analysis of energy loss mediated by an alpha-1 blocker in patients with benign prostatic hyperplasia using a virtual urethra processed from an endoscopic video image.

To examine the efficacy of an alpha-1 blocker and its correlation to structural alteration of the prostatic urethra and the loss of energy in the urine flow using a virtual urethra processed from an endoscopic video image. Video images of the prostatic urethra were recorded during cystourethroscopy in 11 patients with benign prostatic hyperplasia (BPH) before and after treatment with an alpha-1 blocker, naftopidil. The three-dimensional (3D) structure of the prostatic urethra was reproduced from video files. Fluid dynamic analysis and hydraulic energy calculations were performed using the "virtual" 3D urethral images. In 9 of 11 patients studied, an 11% improvement in the loss of energy (range, 1%-82%) was seen. Alpha-1 blocker treatment mediated the disappearance or decrease of the bulky vortex formation in seven patients, which led to an improved urinary stream. A positive correlation was found between improved energy loss and residual urine volume (P=0.0312). Alpha-1 blocker therapy led to a decreased energy loss in the urine flow in the prostatic urethra in relation to the improvement of clinical symptoms. The cystourethroscopy could be a tool to assess the urethral resistance in patients with BPH using image processing methodology.