Magnetic resonance imaging of cardiac function and myoca

在射血前，心肌的顺应性对于心脏的正常充盈是重要的。去年，我们首次对心肌的弹性和粘性进行了非侵入性测量。我们使用了由我们称为DENSE的小组开发的MRI相移技术。我们获得了非常不同的结果，在跳动的心脏，从以前公布的数字在孤立的组织样本。活的肌肉明显更柔顺，粘性更低。基于这些数据，我们计划研究影响心肌硬度的生理条件，并将此测量扩展到人类志愿者和潜在的舒张功能障碍患者。 我们还进行了基于图像的心肌血容量和毛细血管中的平均流速的测量。我们观察到毛细血管在主动脉壁中有组织的定向。我们的数据也支持这样的观点，即与其他器官不同，心脏中的微循环就像海绵一样振荡，被肌肉收缩本身周期性地挤压。这对如何将均匀的新鲜血液输送到心肌具有影响。我们现在正在进行测量，以衡量区域灌注和心肌的工作输出的异质性程度。我们还对心肌的挤压效应进行直接成像，以更好地了解这种特殊的血流动力学。

The compliance of the cardiac muscle in diastole is important to normal filling of the heart prior to ejection. In the last year we performed the first non-invasive measurements of the elasticity and viscousity of the myocardium. We did this using a MRI phase-shift technique developed by our group called DENSE. We obtained very different results in the beating heart from previously published numbers obtained in isolated tissue samples. The living muscle is markedly more compliant and less viscous. Based on these data we plan to look into the physiological conditions that affect myocardial stiffness, and extend this measurement to human volunteers and potentially patients with diastolic dysfunction. We also performed image based measurements of the blood volume of the myocardium and mean flow velocity in the capillaries. We observed the organized orientation of the capillaries in the mocardial wall. Our data also supported the notion that unlike other organs, microcirculation in the heart oscillates like a the sponge being periodically squeezed by the muscle contraction itself. This has implications on how uniform fresh blood is delivered to the heart muscle. We are now conducting measurements to gauge the degree of heterogeneity in regional perfusion and work output of the myocardium. We are also performing direct imaging of the squeezing effect of the myocardium to better understand this particular dynamics of blood flow.