Department of Mechanical Engineering, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, PA, 15213, USA.
Department of Neurology, Allegheny General Hospital, 490 E North Avenue, Pittsburgh, PA, 15212, USA.
Ann Biomed Eng. 2024 Dec;52(12):3184-3195. doi: 10.1007/s10439-024-03581-2. Epub 2024 Jul 8.
Individual facial soft tissue properties are necessary for creating individualized finite element (FE) models to evaluate medical devices such as continuous positive airway pressure (CPAP) masks. There are no standard tools available to measure facial soft tissue elastic moduli, and techniques in literature require advanced equipment or custom parts to replicate.
We propose a simple and inexpensive soft tissue measurement (STM) indenter device to estimate facial soft tissue elasticity at five sites: chin, cheek near lip, below cheekbone, cheekbone, and cheek. The STM device consists of a probe with a linear actuator and force sensor, an adjustment system for probe orientation, a head support frame, and a controller. The device was validated on six ballistics gel samples and then tested on 28 subjects. Soft tissue thickness was also collected for each subject using ultrasound.
Thickness and elastic modulus measurements were successfully collected for all subjects. The mean elastic modulus for each site is E = 53.04 ± 20.97 kPa for the chin, E = 16.33 ± 8.37 kPa for the cheek near lip, E = 27.09 ± 11.38 kPa for below cheekbone, E = 64.79 ± 17.12 kPa for the cheekbone, and E = 16.20 ± 5.09 kPa for the cheek. The thickness and elastic modulus values are in the range of previously reported values. One subject's measured soft tissue elastic moduli and thickness were used to evaluate custom-fit CPAP mask fit in comparison to a model of that subject with arbitrary elastic moduli and thickness. The model with measured values more closely resembles in vivo leakage results.
Overall, the STM provides a first estimate of facial soft tissue elasticity and is affordable and easy to build with mostly off-the-shelf parts. These values can be used to create personalized FE models to evaluate custom-fit CPAP masks.
为了评估医疗设备（如持续气道正压通气（CPAP）面罩），需要创建个体化的有限元（FE）模型，这就需要用到个体面部软组织特性。目前尚无可用于测量面部软组织弹性模量的标准工具，文献中的技术需要使用先进的设备或定制部件来复制。
我们提出了一种简单且经济的软组织测量（STM）压入器设备，可在五个部位（下巴、嘴唇附近的脸颊、颧骨下方、颧骨和脸颊）估计面部软组织的弹性。STM 设备由带有线性致动器和力传感器的探头、探头方向调节系统、头部支撑框架和控制器组成。该设备在六个弹道凝胶样本上进行了验证，然后在 28 名受试者上进行了测试。还使用超声为每位受试者收集了软组织厚度。
所有受试者均成功采集到厚度和弹性模量测量值。每个部位的平均弹性模量为：下巴处 E=53.04±20.97 kPa，嘴唇附近的脸颊处 E=16.33±8.37 kPa，颧骨下方处 E=27.09±11.38 kPa，颧骨处 E=64.79±17.12 kPa，脸颊处 E=16.20±5.09 kPa。厚度和弹性模量值在先前报道的范围内。一位受试者的测量软组织弹性模量和厚度用于评估与该受试者具有任意弹性模量和厚度的模型相比的定制 CPAP 面罩适配。具有测量值的模型更接近体内泄漏结果。
总体而言，STM 提供了面部软组织弹性的初步估计，价格实惠且易于构建，主要使用现成的部件。这些值可用于创建个性化的 FE 模型，以评估定制 CPAP 面罩的适配性。
