Magnetic resonance imaging of cardiac function and myoca

舒张期心肌的顺应性对射血前心脏的正常充盈很重要。去年，我们首次进行了心肌弹性和黏度的非侵入性测量。我们使用了我们小组开发的MRI相移技术，叫做DENSE。我们在跳动的心脏中获得的结果与之前发表的在分离组织样本中获得的结果非常不同。活肌肉明显更柔顺，更少粘稠。基于这些数据，我们计划研究影响心肌硬度的生理条件，并将这项测量扩展到人类志愿者和潜在的舒张功能障碍患者。

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.