Bambi G, Morganti T, Ricci S, Boni E, Guidi F, Palombo C, Tortoli P
Department of Electronics and Telecommunications, University of Florence, Via Santa Marta 3, Firenze 50139, Italy.
Ultrasonics. 2004 Apr;42(1-9):731-7. doi: 10.1016/j.ultras.2003.11.008.
The study of arterial mechanics concerns functional characteristics depending on wall elasticity and flow profile. Wall elasticity can be investigated through the estimation of parameters like the arterial distensibility, which is of high clinical interest because of its known correlation not only with the advanced atherosclerotic disease, but also with aging and major risk factors for cardiovascular disease. The flow velocity profile is also clinically relevant, because it modulates endothelial function and can be responsible for the development and distribution of atherosclerotic plaques. A clinically relevant variable extracted from the blood velocity profile is the wall shear rate (WSR), which represents the spatial velocity gradient near the vessel wall. This paper describes an integrated ultrasound system, capable of detecting both the velocity profile and the wall movements in human arteries. It basically consists of a PC add-on board including a single high-speed digital signal processor. This is dedicated to the analysis of echo-signals backscattered from 128 range cells located along the axis of the interrogating ultrasound (US) beam. Echoes generated from the walls (characterized by high amplitudes and low Doppler frequencies) and from red blood cells (characterized by low amplitudes and relatively high Doppler frequencies) are independently processed in real-time. Wall velocity is detected through the autocorrelation algorithm, while blood velocity is investigated through a complete spectral analysis of all signals backscattered by erythrocytes and WSR is extracted from the estimated velocity profile. Preliminary applications of the new system, including the simultaneous analysis of blood flow and arterial wall movement in healthy volunteers and in a diseased patient, are discussed, and first results are presented.
动脉力学研究关注取决于血管壁弹性和血流剖面的功能特性。血管壁弹性可通过诸如动脉扩张性等参数的估计来研究，由于其不仅与晚期动脉粥样硬化疾病相关，还与衰老及心血管疾病的主要风险因素有关，因此具有很高的临床研究价值。血流速度剖面在临床上也具有相关性，因为它调节内皮功能，并且可能导致动脉粥样硬化斑块的形成和分布。从血流速度剖面中提取的一个与临床相关的变量是壁面切应力（WSR），它表示血管壁附近的空间速度梯度。本文描述了一种集成超声系统，能够检测人体动脉中的速度剖面和血管壁运动。它主要由一块包含单个高速数字信号处理器的PC扩展板组成。该处理器专门用于分析沿超声（US）探测波束轴线上128个距离单元反向散射的回波信号。从血管壁（具有高幅度和低多普勒频率特征）和红细胞（具有低幅度和相对高多普勒频率特征）产生的回波被实时独立处理。通过自相关算法检测血管壁速度，而通过对红细胞反向散射的所有信号进行完整的频谱分析来研究血流速度，并从估计的速度剖面中提取壁面切应力。讨论了新系统的初步应用，包括对健康志愿者和患病患者的血流与动脉壁运动的同步分析，并展示了初步结果。
