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Ishii T, Yamanishi T, Kamasako T, Shibata C, Fuse M, Kaga M, Kaga K, Nahas H, Yiu BYS, Yu ACH, Saijo Y. Transrectal ultrasound vector projectile imaging for time-resolved visualization of flow dynamics in the male urethra: A clinical pilot study. Med Phys 2024; 51:428-438. [PMID: 37983613 DOI: 10.1002/mp.16834] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Revised: 10/14/2023] [Accepted: 10/30/2023] [Indexed: 11/22/2023] Open
Abstract
BACKGROUND Quantitative and comprehensive visualization of urinary flow dynamics in the urethra is crucial for investigating patient-specific mechanisms of lower urinary tract symptoms (LUTS). Although some methods can evaluate the global properties of the urethra, it is critical to assess the local information, such as the location of the responsible lesion and its interactions with urinary flow in relation to LUTS. This approach is vital for enhancing personalized and focal treatments. However, there is a lack of such diagnostic tools that can directly observe how the urethral shape and motion impact urinary flow in the urethra. PURPOSE This study aimed to develop a novel transrectal ultrasound imaging modality based on the contrast-enhanced urodynamic vector projectile imaging (CE-UroVPI) framework and validate its clinical applicability for visualizing time-resolved flow dynamics in the urethra. METHODS A new CE-UroVPI system was developed using a research-purpose ultrasound platform and a custom transrectal linear probe, and an imaging protocol for acquiring urodynamic echo data in male patients was designed. Thirty-four male patients with LUTS participated in this study. CE-UroVPI was performed to acquire ultrasound echo signals from the participant's urethra and urinary flow at various voiding phases (initiation, maintenance, and terminal). The ultrasound datasets were processed with custom software to visualize urinary flow dynamics and urethra tissue deformation. RESULTS The transrectal CE-UroVPI system successfully visualized the time-resolved multidirectional urinary flow dynamics in the prostatic urethra during the initiation, maintenance, and terminal phases of voiding in 17 patients at a frame rate of 1250 fps. The maximum flow speed measured in this study was 2.5 m/s. In addition, when the urethra had an obstruction or an irregular partial deformation, the devised imaging modality visualized complex flow patterns, such as vortices and flow jets around the lesion. CONCLUSIONS Our study findings demonstrate that the transrectal CE-UroVPI system developed in this study can effectively image fluid-structural interactions in the urethra. This new diagnostic technology has the potential to facilitate quantitative and precise assessments of urethral voiding functions and aid in the improvement of focal and effective treatments for patients with LUTS.
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Affiliation(s)
- Takuro Ishii
- Frontier Research Institute for Interdisciplinary Sciences, Tohoku University, Sendai, Miyagi, Japan
- Graduate School of Biomedical Engineering, Tohoku University, Sendai, Miyagi, Japan
| | - Tomonori Yamanishi
- Continence Center, Dokkyo Medical University Hospital, Utsumomiya, Tochigi, Japan
| | - Tomohiko Kamasako
- Continence Center, Dokkyo Medical University Hospital, Utsumomiya, Tochigi, Japan
| | - Chiharu Shibata
- Continence Center, Dokkyo Medical University Hospital, Utsumomiya, Tochigi, Japan
| | - Miki Fuse
- Continence Center, Dokkyo Medical University Hospital, Utsumomiya, Tochigi, Japan
| | - Mayuko Kaga
- Continence Center, Dokkyo Medical University Hospital, Utsumomiya, Tochigi, Japan
| | - Kanya Kaga
- Continence Center, Dokkyo Medical University Hospital, Utsumomiya, Tochigi, Japan
| | - Hassan Nahas
- Research Institute for Aging, University of Waterloo, Waterloo, Ontario, Canada
| | - Billy Y S Yiu
- Research Institute for Aging, University of Waterloo, Waterloo, Ontario, Canada
| | - Alfred C H Yu
- Research Institute for Aging, University of Waterloo, Waterloo, Ontario, Canada
| | - Yoshifumi Saijo
- Graduate School of Biomedical Engineering, Tohoku University, Sendai, Miyagi, Japan
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Minagawa T, Saito T, Ueno M, Ogawa T, Ishizuka O. Initial clinical results of fluid dynamical approach for lower urinary tract function using a high-speed video camera. Int J Urol 2022; 30:415-416. [PMID: 36541166 DOI: 10.1111/iju.15126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Tomonori Minagawa
- Department of Urology, Shinshu University School of Medicine, Matsumoto, Nagano, Japan
| | - Tetsuichi Saito
- Department of Urology, Shinshu University School of Medicine, Matsumoto, Nagano, Japan
| | - Manabu Ueno
- Department of Urology, Shinshu University School of Medicine, Matsumoto, Nagano, Japan
| | - Teruyuki Ogawa
- Department of Urology, Shinshu University School of Medicine, Matsumoto, Nagano, Japan
| | - Osamu Ishizuka
- Department of Urology, Shinshu University School of Medicine, Matsumoto, Nagano, Japan
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Jang KS, Kim JW, Ryu J. Numerical investigation of urethra flow characteristics in benign prostatic hyperplasia. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2022; 224:106978. [PMID: 35797748 DOI: 10.1016/j.cmpb.2022.106978] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Revised: 04/05/2022] [Accepted: 06/25/2022] [Indexed: 06/15/2023]
Abstract
BACKGROUND AND OBJECTIVE Conventional practice includes a limited depiction of urethral pressure and flows based on fragmented gross clinical observations. However, with technological advancements in simulations, computational fluid dynamics (CFD) can provide an alternative approach to predict the bladder pressure with a concordant quantitative flow field in the urethra. Thus, this study aims to comprehensively analyze the urine flow characteristics in various urethra models using simulations. METHODS Three-dimensional urethra models were constructed for seven specific subjects based on clinical radiographs. Simulations with Reynolds averaged Navier-Stokes model were performed to quantitatively investigate the urine flow under various volume flow rate of voided urine. RESULTS Under benign prostatic hyperplasia, the spindle shape of the prostatic urethra (PRU) generates wake flow. The wake flow was also observed in several regions downstream of the PRU, depending on the urethra shape. This wake flow resulted in total pressure loss and urinary tract dysfunction. When comparing pre- and post-operative urethra models, the bladder pressure decreased by 14.98% in P04 and 4.67% in P06. Thus, we identified variability between surgical results of patients. The bladder pressure according to the volume flow rate of voided urine was investigated using simulations and the theoretical consideration based on hydrodynamics. In theoretical consideration, the bladder pressure was expressed as a second-order polynomial for volume flow rate. These results concur with the simulation results. CONCLUSION Numerical simulation can describe the urine flow field in the urethra, providing the possibility to predict the bladder pressure without requiring painful, invasive interventions, such as cystoscopy. Furthermore, effective treatments to improve urination function can be formulated to be patient-specific, by detecting causes and problem regions based on quantitative analysis and predicting post-surgical outcomes.
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Affiliation(s)
- Kyeong Sik Jang
- PKG Design Team, Test& System Package (TSP), Samsung Electronics, Gyeonggi-do 18448, Republic of Korea
| | - Jin Wook Kim
- Department of Urology, Chung-Ang University, Seoul 06974, Republic of Korea; Biomedical Research Institute, Chung-Ang University Hospital, Seoul 06973, Republic of Korea.
| | - Jaiyoung Ryu
- Department of Mechanical Engineering, Chung-Ang University, Seoul 06974, Republic of Korea; Department of Intelligent Energy and Industry, Chung-Ang University, Seoul 06974, Republic of Korea.
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Zhang B, Liu S, Liu Y, Wu B, Zhang X, Wang X, Liang X, Cao X, Wang D, Wu CL. Novel CFD modeling approaches to assessing urine flow in prostatic urethra after transurethral surgery. Sci Rep 2021; 11:663. [PMID: 33436678 PMCID: PMC7804846 DOI: 10.1038/s41598-020-79505-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Accepted: 11/30/2020] [Indexed: 11/09/2022] Open
Abstract
Assessment of the pressure and velocity of urine flow for different diameter ratios of prostatic urethra (RPU) after transurethral surgery using computational fluid dynamics (CFD). A standardized and idealized two-dimensional CFD model after transurethral surgery (CATS-1st) was developed for post-surgery mid-voiding. Using CATS-1st, 210 examples were amplified according to an array of size [3][5][14], which contained three groups of longitudinal diameters of prostatic urethra (LD-PU). Each of these groups contained five subgroups of transverse diameters of the bladder neck (TD-BN), each with 14 examples of transverse diameters of PU (TD-PU). The pressure and velocity of urine flow were monitored through flow dynamics simulation, and the relationship among RPU-1 (TD-PU/TD-BN), RPU-2 (RPU-1/LD-PU), the transverse diameter of the vortex, and the midpoint velocity of the external urethral orifice (MV-EUO) was determined. A total of 210 CATS examples, including CATS-1st examples, were analyzed. High (bladder and PU) and medium/low (the rest of the urethra) pressure zones, and low (bladder), medium (PU), and high (the rest of the urethra) velocity zones were determined. The rapid changes in the velocity were concentrated in and around the PU. Laminar flow was present in all the examples. The vortices appeared and then gradually shrank with reducing RPU on both the sides of PU in 182 examples. In the vortex examples, minimum RPU-1 and RPU-2 reached close to the values of 0.79 and 0.02, respectively. MV-EUO increased gradually with decreasing RPU. In comparison to the vortex examples, the non-vortex examples exhibited a significantly higher (p < 0.01) MV-EUO. The developed CFD models (CATS) presented an effective simulation of urine flow behavior within the PU after transurethral surgery for benign prostatic hyperplasia (BPH). These models could prove to be useful for morphological repair in PU after transurethral surgery.
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Affiliation(s)
- Bin Zhang
- Department of Urology, First Hospital of Shanxi Medical University, Taiyuan, 030001, Shanxi, China.,Department of Urology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, 02114, USA
| | - Shuang Liu
- Department of Urology, First Hospital of Shanxi Medical University, Taiyuan, 030001, Shanxi, China
| | - Yinxia Liu
- Department of Obstetrics and Gynecology, Shanxi Health Vocational College, Shanxi Traditional Chinese Medicine School, Jinzhong, 030600, Shanxi, China
| | - Bo Wu
- Department of Urology, First Hospital of Shanxi Medical University, Taiyuan, 030001, Shanxi, China
| | - Xuhui Zhang
- Department of Urology, First Hospital of Shanxi Medical University, Taiyuan, 030001, Shanxi, China
| | - Xin Wang
- Department of Urology, First Hospital of Shanxi Medical University, Taiyuan, 030001, Shanxi, China
| | - Xuezhi Liang
- Department of Urology, First Hospital of Shanxi Medical University, Taiyuan, 030001, Shanxi, China
| | - Xiaoming Cao
- Department of Urology, First Hospital of Shanxi Medical University, Taiyuan, 030001, Shanxi, China
| | - Dongwen Wang
- National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital & Shenzhen Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, No. 113 Baohe road, Longgang district, Shenzhen, 518116, China. .,First College of Clinical Medicine, Shanxi Medical University, Taiyuan, 030001, Shanxi, China.
| | - Chin-Lee Wu
- Department of Urology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, 02114, USA.,Department of Pathology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, 02114, USA
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