MRI of cardiac function and myocardial tissue properties

舒张期心肌的顺应性对射血前心脏的正常充盈很重要。在许多心脏收缩功能正常的心力衰竭患者中，“心脏僵硬综合征”可能是由心肌僵硬引起的。在去年，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，证明了它在人类中的可行性，并显示了缺血性损伤后肌肉的僵硬。我们现在有一个方案来观察高血压患者，看看肌肉不适是否对他们的状况负有特别的责任。

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.