MRI of cardiac function and myocardial tissue properties

在射血前，心肌的顺应性对于心脏的正常充盈是重要的。在许多收缩功能正常的心力衰竭患者中，“僵硬心脏综合征”可能是由僵硬的心肌引起的。在过去的一年中，我们已经证实了一种非侵入性的，基于MRI的心肌顺应性测量的准确性，证明了其在人类中的可行性，并显示了缺血性损伤后肌肉的僵硬。我们现在有一个协议，看看高血压患者，看看肌肉抱怨是不是他们的条件特别负责。 我们还观察到心脏中血流的一个独特特征，即由于心脏收缩的挤压效应，冠状动脉树的小分支中的动脉和静脉流动是异相的。我们测量了由于这种效应引起的组织体积变化，这给出了心脏壁灌注的独立估计，并指出了心脏中机械功和氧气输送非常及时耦合的机制。

The compliance of the cardiac muscle in diastole is important to normal filling of the heart prior to ejection. In many heart failure patients with normal systolic function, the "stiff heart syndrome" is likely caused by stiffened heart muscle. In the last year we have confirmed the accuracy of a non-invasive, MRI based measurement of heart muscle compliance, demonstrated its feasibility in humans, and showed the stiffening of the muscle following ischemic injury. We now have a protocol to look at patients with hypertension to see if muscle complaince is specifically responsible for their conditions. We also observed a unique feature of blood flow in the heart, the out-of-phase arterial and venous flow in small branches of the coronary tree due to of the squeezing effect of heart contraction. We measuremented tissue volume changes due to this effect, which give an independent estimate of perfusion of the heart wall, and points to a mechanism of very timely coupling of mechanical work and oxygen delivery in the heart.