Finite element analysis of male lower urinary tract based on the collodion slice images
1. College of Mechanical Engineering, Tianjin University of Science and Technology, Tianjin 300222, P.R.China
2. The Key Laboratory of Integrated Design and On-Line Monitoring of Light Industrial and Food Engineering Machinery and Equipment in Tianjin, Tianjin 300222, P.R.China
3. School of Basic Medicine, Medical University of Tianjin, Tianjin 300070, P.R.China
男性原发性膀胱颈梗阻发病率高，而现有尿动力学检查方法具有侵入性，且易造成误诊或漏诊。因此为构建男性下尿路非侵入式生物力学检测系统，本文基于正常男性下尿路火棉胶切片图像构建出下尿路有限元模型，并模拟真实排尿环境，进行流固耦合仿真分析。通过对比下尿路临床试验数据与仿真结果，验证了下尿路有限元模型的有效性。本文进一步对下尿路变形、应力与尿流速率等参数进行了分析，结果表明正常男性下尿路模型中膜部括约肌处米塞斯应力与壁面切应力均达到峰值，并且与膀胱压力曲线的峰值在时间上有 1 s 左右的尿流延迟，模型还原度良好。本文的研究结果为进一步开展对下尿路梗阻模型膀胱压、尿流率等尿动力学的响应机理研究奠定了基础，可为非侵入式生物力学检测系统的研发提供理论依据。
Males typically have high rates of morbidity of primary bladder neck obstruction, while the existing urodynamic examination is invasive and more likely to cause false diagnosis. To build a non-invasive biomechanical detecting system for the male lower urinary tract, a finite element model for male lower urinary tract based on the collodion slice images of normal male lower urinary tract was constructed, and the fluid-structure interaction of the lower urinary tract was simulated based on the real urination environment. The finite element model of the lower urinary tract was validated by comparing the clinical experiment data with the simulation result. The stress, flow rate and deformation of the lower urinary tract were analyzed, and the results showed that the Von Mises stress and the wall shear stress at the membrane sphincter in the normal male lower urinary tract model reached a peak, and there was nearly 1 s delay than in the bladder pressure, which helped to validate the model. This paper lays a foundation for further research on the urodynamic response mechanism of the bladder pressure and flow rate of the lower urinary tract obstruction model, which can provide a theoretical basis for the research of non-invasive biomechanical detecting system.
Zhai Lidong, Liu Jin, Li Yunsheng, et al. The male rectourethralis and deep transverse perineal muscles and their relationship to adjacent structures examined with successive slices of celloidin-embedded pelvic viscera. Eur Urol, 2011, 59(3): 415-421.
Boubaker M B, Haboussi M, Ganghoffer J F, et al. Predictive model of the prostate motion in the context of radiotherapy: a biomechanical approach relying on urodynamic data and mechanical testing. J Mech Behav Biomed Mater, 2015, 49(6): 30-42.
Samavati N, Mcgrath D M, Jewett M A, et al. Effect of material property heterogeneity on biomechanical modeling of prostate under deformation. Phys Med Biol, 2015, 60(1): 195-209.
Boubaker M B, Haboussi M, Ganghoffer J F, et al. Finite element simulation of interactions between pelvic organs: predictive model of the prostate motion in the context of radiotherapy. J Biomech, 2009, 42(12): 1862-1868.
Bréaud J, Montoro J, Lecompte J F, et al. Posterior urethral injuries associated with motorcycle accidents and pelvic trauma in adolescents: analysis of urethral lesions occurring prior to a bony fracture using a computerized finite-element model. J Pediatr Urol, 2013, 9(1): 62-70.
Wang Yi, Cheng Jiezhi, Ni Dong, et al. Towards personalized statistical deformable model and hybrid point matching for robust MR-TRUS registration. IEEE Trans Med Imaging, 2016, 35(2): 589-604.
Aenis M, Stancampiano A P, Wakhloo A K, et al. Modeling of flow in a straight stented and nonstented side wall aneurysm model. J Biomech Eng, 1997, 119(2): 206-212.