Department of Radiation Oncology, University of California San Francisco, San Francisco, CA, USA.
Acoustic MedSystems, Inc., Savoy, IL, USA.
Med Biol Eng Comput. 2020 Jun;58(6):1325-1340. doi: 10.1007/s11517-020-02152-6. Epub 2020 Apr 10.
The purpose of this study is to investigate the feasibility and performance of a stationary, non-focused dual-sectored tubular transurethral ultrasound applicator for thermal exposure of tissue regions adjacent to the urethra for treatment of stress urinary incontinence (SUI) through acoustic and biothermal simulations on 3D anatomical models. Parametric studies in a generalized tissue model over dual-sectored ultrasound applicator configurations (acoustic surface intensities, lateral active acoustic output sector angles, and durations) were performed. Selected configurations and delivery strategies were applied on 3D pelvic anatomical models. Temperature and thermal dose distributions on the target region and surrounding tissues were calculated. Endovaginal cooling was explored as a strategy to mitigate vaginal heating. The 75-90° dual-sectored transurethral tubular transducer (3.5 mm outer diameter (OD), 14 mm length, 6.5 MHz, 8.8-10.2 W/cm) and 2-3-min sonication duration were selected from the parametric study for acoustic and biothermal simulations on anatomical models. The transurethral applicator with two opposing 75-90° active lateral tubular sectors can create two heated volumes for a total of up to 1.8 cm over 60 EM, with at least 10 mm radial penetration depth, 1.2 mm urethral sparing, and no lethal damage to the vagina and adjacent bone (< 60 EM). Endovaginal cooling can be applied to further reduce the vaginal wall exposure (< 15 EM). Simulations on 3D anatomical models indicate that dual-sectored transurethral ultrasound applicators can selectively heat pelvic floor tissue lateral to the mid-urethra in short treatment durations, without damaging adjacent vaginal and bone tissues, as a potential alternative treatment option for stress urinary incontinence. Graphical abstract Schema for in silico investigation of transurethral ultrasound thermal therapy applicator for minimally invasive treatment of SUI.
本研究旨在通过对 3D 解剖模型进行声学和生物热模拟，探讨一种用于经尿道热疗治疗压力性尿失禁（SUI）的固定、非聚焦双扇形管状经尿道超声应用器的可行性和性能。在双扇形超声应用器配置（声表面强度、侧向有源声输出扇区角度和持续时间）的广义组织模型中进行了参数研究。将选定的配置和输送策略应用于 3D 骨盆解剖模型。计算目标区域和周围组织的温度和热剂量分布。探索阴道内冷却作为减轻阴道加热的策略。从参数研究中选择了 75-90°双扇形经尿道管状换能器（3.5mm 外径（OD）、14mm 长度、6.5MHz、8.8-10.2W/cm）和 2-3 分钟的超声持续时间，用于解剖模型上的声学和生物热模拟。带有两个相对的 75-90°有源侧向管状扇区的经尿道应用器可以在总共 60 EM 内创建两个加热体积，总加热体积可达 1.8cm，径向穿透深度至少 10mm，尿道保留 1.2mm，阴道和相邻骨骼无致命损伤（<60 EM）。阴道内冷却可进一步减少阴道壁暴露（<15 EM）。3D 解剖模型上的模拟表明，双扇形经尿道超声应用器可以在短治疗时间内选择性加热尿道中部外侧的盆底组织，而不会损伤相邻的阴道和骨骼组织，作为治疗压力性尿失禁的潜在替代选择。
