Quantitative evaluation of local biomechanics of thoracic aorta

本研究的目的是建立一套应用超声诊断装置定量测量主动脉壁生物力学的系统，并建立动脉瘤破裂和手术的客观指征。资助期间研究的具体目的是利用血管内超声（IVUS）和经食管超声心动图测量主动脉壁局部弹性。（TEE）临床IVUS仪器的射频（RF）信号通过模拟/数字（A/D）转换器采样，采样率为500 MSa/s，存储在工作站。同时通过10 kSa/s的A/D转换器采集心电图和冠状动脉内压。计算了同一地址的射频线在相邻火焰中的相关性和位移。假设高相关区域为血管壁，进行血管壁的自动识别。组织速度计算为帧差为33 ms。组织速度成像定义为高相关区域的组织速度。中心频率为4 ~ 7mhz的TEE获得降主动脉短轴图。同时记录心电图和血压。采用相邻帧中兴趣区域平方的模板匹配方法计算二维组织速度、向量。将IVUS结果与冠脉定向切除标本进行比较，TEE结果与手术切除标本进行比较。血压变化引起的被动运动与组织成分和巨噬细胞等炎症细胞的表达相关。最后，提出了利用超声技术精确测量生物力学的方法。

The objectives of the present study are to develop a quantitative measurement system of biomechanics of aortic wall by applying ultrasound diagnostics device and to establish an objective indication for rupture of aneurysm and operation. The concrete object of the research during grant-in-aid is to measure the local elasticity of aortic wall by using intravascular ultrasound (IVUS) and transesophageal echocardiography. (TEE)Radio-frequency (RF) signal of clinical IVUS apparatus was sampled via analogue/digital (A/D) converter with sampling rate of 500 MSa/s and stored in a workstation. Electrocardiogram and intracoronary pressure were also sampled via A/D converter with 10 kSa/s, simultaneously. The correlation and displacement of RF lines of the same address in neighboring flames were calculated. Assuming that high correlation area indicated vascular wall, automatic recognition of vascular wall was performed. Tissue velocity was calculated as the difference of the frames was 33 ms. Tissue Velocity Imaging was defined as the tissue velocity in high correlation areas. Short axis view of descending aorta was obtained by a TEE with the central frequency of 4-7 MHz. Electrocardiogram and blood pressure were recorded simultaneously. Two dimensional tissue velocity, vectors were calculated by template matching method of squared region of interests in neighboring frames. IVUS findings and excised specimen by directional coronary atherectomy were compared and TEE findings and surgicaly excised specimen were compared The passive movement by blood pressure variance was correlated with tissue components and expression of inflammatory cells such as macrophages. Finally, precise measurement of biomechanics by applying ultrasonic technology was shown in the present research.