Kim Kang, Weitzel W F, Rubin J M, Xie Hua, Chen Xunchang, O'Donnell M
Department of Biomedical Engineering, University of Michigan, Ann Arbor, 48109-2099, USA.
Ultrasound Med Biol. 2004 Jun;30(6):761-71. doi: 10.1016/j.ultrasmedbio.2004.04.003.
Peripheral vascular strain imaging has limited strain dynamic range because arterial wall deformations only exhibit small strains under physiologic pressures. A noninvasive freehand ultrasound (US) scanning procedure was performed to apply external force, comparable to the force generated in measuring a subject's blood pressure, to achieve higher strains by equalizing the internal arterial baseline pressure. When the applied pressure matched the internal baseline diastolic pressure, intramural strain and strain rate increased by a factor of 10 over a cardiac cycle. Radial arterial strain was assessed within the vessel wall over the entire deformation procedure using a phase-sensitive 2-D speckle-tracking algorithm. The feasibility of this technique to assess vascular nonlinear elastic properties is demonstrated in an ex vivo experiment and further supported by in vivo measurements. With some uncertainty associated with the elastic properties of surrounding tissue, an elastic modulus reconstruction procedure was developed to estimate the nonlinear elastic properties of the vascular wall.
外周血管应变成像的应变动态范围有限，因为在生理压力下动脉壁变形仅表现出微小应变。进行了一种无创徒手超声（US）扫描程序，以施加与测量受试者血压时产生的力相当的外力，通过平衡动脉内部基线压力来实现更高的应变。当施加的压力与内部基线舒张压匹配时，在一个心动周期内，壁内应变和应变率增加了10倍。在整个变形过程中，使用相敏二维散斑追踪算法在血管壁内评估桡动脉应变。该技术评估血管非线性弹性特性的可行性在离体实验中得到了证明，并通过体内测量得到了进一步支持。由于周围组织弹性特性存在一些不确定性，开发了一种弹性模量重建程序来估计血管壁的非线性弹性特性。
