血管弹性重构方法的研究

Reconstructive Method of Microscopic Elasticity Images of Vascular Tissues Based on Intravascular Ultrasound

在血管内施加静态压力，由血管内超声成象与二维运动估计方法获得血管壁组织内位移与应变分布后，在国际上首次重构获得了不同应变条件下真正意义上的血管壁组织弹性显微分布图象，在血管小应变条件下，确定弹性明显差异区域与边界，求解应力平衡方程来重构血管组织弹性分布；在血管大应变条件下，利用牛顿－拉斐逊法使迭代逼近位移与运动估计实验位移的均方误差为最小来重构血管弹性分布．离体猪血管实验结果证实了文中提出的血管弹性显微图象重构方法的合理性，并抑制了应变成象中的噪声，将血管力学在体实验研究推进到二维或多维亚毫米微结构层次，对血管力学基础研究和ＰＴＣＡ过程监控与疗效评价具有重要价值。

A static pressure was applied in the artery. The displacement and strain distributions of artery wall tissue were estimated using high frequency intravascular ultrasound imaging and two-dimensional motion estimation. The authors obtained 'real' elasticity distribution images of different strain vascular tissues for the first time in the world by the reconstructive methods proposed in this paper. When arteries are in the small strain condition, the regions and boundaries of clear elasticity distribution variation are roughly identified. The vascular tissue elasticity distributions are reconstructed by using stress equlibrium equations. When arteries are in the large strain and nonlinear condition, the Newton-Raphson method is used to minimizes the least square error between experimentally estimated and theoretically predicted displacement fields so as to reconstruct elasticity distribution. The vitro experimental results of porcine artery demonstrates that the linear and nonlinear elasticity reconstructive methods are reasonable. The artifacts in the strain imaging can be reduced. Experimental research of vascular mechanics can be advanced to 2D or 3D sub-millimeter microstructure levels. These studies are of great importance in fundamental research of vascular mechanics and in the monitoring and evaluation of PTCA process.