An Investigation on Noninvasive Measurement of Transmural Distribution of Myocardial Systolic Function and Diastolic Properties Using Ultrasound

对于严重的心脏疾病，不同的跨壁心肌层在收缩强度方面具有跨壁异质性。一种测量这种具有足够空间分辨率的跨壁异质性的方法从未被开发出来。本研究提出了一种无创测量心内收缩/舒张非均匀性的方法，即通过测量厚度或速度的二维变化来测量心内收缩/舒张非均匀性。提出了一种测量心肌粘弹性的新方法，并通过基础实验和体内实验验证了其原理。本研究提出了一种无创测量心内收缩/舒张异质性的方法，即通过测量厚度或速度的二维变化来测量心内收缩/舒张异质性。以物理参数已知的硅橡胶球壳为模拟心脏模型，进行了基础实验，验证了该方法测量的准确性。此外，本研究还开发了一种新的方法，用于无创测量舒张期开始时的心肌粘弹性，并用于成像弹性波传播的跨壁异质性。该方法适用于健康受试者和心脏病患者。通过这种方法，可以成功地检测到心壁的速度信号，并且具有足够的重现性。在这项研究中，脉冲波几乎同时在沿心脏壁设置的160个点上以足够高的帧率进行测量。通过测量波的傅里叶变换得到的连续空间相位分布，首次清晰地揭示了波沿心壁的传播。基于这一现象，我们开发了一种利用兰姆波在粘弹性板中的传播模型来测量心肌在体内粘弹性的方法。该方法具有无创性评价心肌粘弹性的潜力。少

For the serious heart diseases, the different transmural layers of the myocardium have transmural heterogeneity with respect to the strength of contraction. A method for measuring such transmural heterogeneity with sufficient spatial resolution has never been developed. In this study, a method for noninvasive measurement of the intramyocardial contraction/relaxation heterogeneity by evaluating the change in thickness or its speed in two dimensions and its measurement system were developed. Moreover, a novel method for measuring the myocardial viscoelasticity was developed and its principle was confirmed by the basic experiments and in vivo experiments as follows :1.In this study, a method for noninvasive measurement of the intramyocardial contraction/relaxation heterogeneity by evaluating the change in thickness or its speed in two dimensions and its measurement system were developed.2.Based on the basic experiments using a spherical shell made of silicone rubber, which physical parame … More ters are known, as a heart-mimicking phantom, the accuracy of the measurement of the developed method was confirmed.3.Moreover, this study developed the following novel method for noninvasively measuring the myocardial viscoelasticity at the beginning of diastole and for imaging the transmural heterogeneity in the propagation of the elastic waves. The method was applied to healthy subjects and patients with heart diseases. By this method, a velocity signal of the heart wall can be successfully detected with sufficient reproducibility. In this study, the pulsive waves were measured almost simultaneously at about 160 points set along the heart wall at a sufficiently high frame rate. The consecutive spatial phase distributions, obtained by the Fourier transform of the measured waves, clearly revealed wave propagation along the heart wall for the first time. Based on this phenomenon, we developed a means to measure the myocardial viscoelasticity in vivo using the model of the Lamb wave propagation in a viscoelastic plate. This method has a potential to noninvasively evaluate the myocardial viscoelasticity. Less