Bracco Marta Irene, Yousefi Ali Akbar Karkhaneh, Rouet Laurence, Avril Stéphane
INSERM, Sainbiose, Mines Saint-Étienne, Saint-Étienne, France.
Philips Research Paris, Suresnes, France.
Ann Biomed Eng. 2025 Jan;53(1):71-82. doi: 10.1007/s10439-024-03608-8. Epub 2024 Sep 4.
Ultrasound imaging is key in the management of patients with an abdominal aortic aneurysm (AAA). It was recently shown that the cyclic diameter variations between diastole and systole, which can be quantified with US imaging, increase significantly with the strength of the applied probe pressure on the patient's abdomen. The goal of this study is to investigate this effect more thoroughly.
With finite-element modeling, pulsatile blood pressure and probe pressure are simulated in three patient-specific geometries. Two distinct models for the aortic wall were simulated: a nonlinear hyperelastic and a linear elastic model. In addition, varying stiffness was considered for the surrounding tissues. The effect of light, moderate, and firm probe pressure was quantified on the stresses and strains in the aortic wall, and on two in vivo stiffness measures. In addition, the Elasticity Loss Index was proposed to quantify the change in stiffness due to probe pressure.
Firm probe pressure decreased the measured aortic stiffness, and material stiffness was affected only when the wall was modeled as nonlinear, suggesting a shift in the stress-strain curve. In addition, stiffer surrounding tissues and a more elongated aneurysm sac decreased the responsiveness to the probe pressure.
The effect of probe pressure on the AAA wall stiffness was clarified. In particular, the AAA wall nonlinear behavior was found to be of primary importance in determining the probe pressure response. Thus, further work will intend to make use of this novel finding in a clinical context.
超声成像在腹主动脉瘤（AAA）患者的管理中起着关键作用。最近的研究表明，舒张期和收缩期之间的周期性直径变化可以通过超声成像进行量化，并且随着施加在患者腹部的探头压力强度的增加而显著增加。本研究的目的是更深入地研究这种效应。
通过有限元建模，在三种特定患者的几何模型中模拟脉动血压和探头压力。模拟了两种不同的主动脉壁模型：非线性超弹性模型和线性弹性模型。此外，还考虑了周围组织的不同刚度。量化了轻、中、强探头压力对主动脉壁应力和应变以及两种体内刚度测量值的影响。此外，还提出了弹性损失指数来量化由于探头压力引起的刚度变化。
强探头压力降低了测量的主动脉刚度，并且只有当壁被建模为非线性时材料刚度才会受到影响，这表明应力 - 应变曲线发生了偏移。此外，周围组织越硬且动脉瘤囊越长，对探头压力的反应性越低。
阐明了探头压力对腹主动脉瘤壁刚度的影响。特别是，发现腹主动脉瘤壁的非线性行为在确定探头压力反应中至关重要。因此，未来的工作将致力于在临床环境中利用这一新发现。
