人體下泌尿道的流體力學機制與其不正常排尿行為存在著密切關係。由於排尿功能異常的型態在泌尿學中有許多種的分類，其中包括神經性質膀胱、膀胱逼尿肌功能異常、尿道幾何形狀過於狹窄或是前列腺腫大壓迫尿道等原因。所以人體下祕尿道的幾何大小形狀、膀胱壓力與不正常排尿有重要關係。膀胱出口阻塞症狀（ＢＯＯ）是一種常見的老年疾病，而現今在臨床上的診斷依據卻又都是用非侵入式的檢測方式，這不僅影響病人的身心健康，還會有感染傳染病的危險。此計畫希望能夠利用數值方法發展一套非侵入式的診斷方法來協助醫師診斷膀胱出口阻塞症狀。研究方法方面，著重在找出尿道流場中影響壓力損失的最主要因素。本研究透過醫學影像分析，取得真實人體下泌尿道的幾何外形，利用影像資料配合影像處理與網格生成技術，重建出真實人體下泌尿道外形的網格系統，再而進行計算流體力學分析，呈現其流場內的壓力與速度分布情形。目的協助醫師判斷病因，並同時可減輕病人在診斷時不論心理或生理上的不適。

In the present study, the aim is to develop a non-invasive measurement technique to diagnose patients having Bladder Outlet Obstruction (BOO). This is achieved by identifying major causes of the pressure loss in the lower urinary system by CFD methods. The CT-scan images are obtained from the Taipei Veterans General Hospital. A sequence of semi-automatic methods proposed by Ching and his co-worker is used to construct rectangular meshes from CT images. Based on the reconstructed 3-D model, CFD analysis is used to determine the detailed flow and pressure distributions within the lower urinary tract system, and it is found that the major causes of the pressure loss exists in the membranous urethra, which is obstructed zone. In the obstructed cases, there are two major losses. One is the major or frictional loss, and the other is the minor loss. Minor loss happens due to the change of geometry. The ratio of the maximum velocity in the prostate urethra to the minimum velocity in the membranous urethra is about 4. This parameter might be a good indication regarding the obstructed condition of the patients. Further studies with different obstructed conditions can be used to examine the influence of this parameter. However, the predicted pressure losses are much lower than that obtained by the field measurements. Part of the reason is that the simulation does not include the bladder, which may also cause excessive pressure loss. Another cause might be the influence of the elastic boundary, which is not accounted in the study.

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