Sack Ingolf, Rump Jens, Elgeti Thomas, Samani Abbas, Braun Jürgen
Department of Radiology, Charité-Universitätsmedizin Berlin, Berlin, Germany.
Magn Reson Med. 2009 Mar;61(3):668-77. doi: 10.1002/mrm.21878.
Many cardiovascular diseases and disorders are associated with hemodynamic dysfunction. The heart's ability to contract and pump blood through the vascular system primarily depends on the elasticity of the myocardium. This article introduces a magnetic resonance elastography (MRE) technique that allows noninvasive and time-resolved measurement of changes in myocardial elasticity over the cardiac cycle. To this end, low-frequency shear vibrations of 24.3 Hz were induced in the human heart via the anterior chest wall. An electrocardiograph (ECG)-triggered, steady-state MRE sequence was used to capture shear oscillations with a frame rate of eight images per vibration cycle. The time evolution of 2D-shear wave fields was observed in two imaging planes through the short axis of the heart in six healthy volunteers. Correlation analysis revealed that wave amplitudes were modulated in synchrony to the heartbeat with up to 2.45 +/- 0.18 higher amplitudes during diastole than during systole (interindividual mean +/- SD). The reduction of wave amplitudes started at 75 +/- 9 ms prior to changes in left ventricular diameter occurring at the beginning of systole. Analysis of this wave amplitude alteration using a linear elastic constitutive model revealed a maximum change in the myocardial wall stiffness of a factor of 37.7 +/- 10.6 during the cardiac cycle.
许多心血管疾病和病症都与血液动力学功能障碍有关。心脏收缩并通过血管系统泵血的能力主要取决于心肌的弹性。本文介绍了一种磁共振弹性成像（MRE）技术，该技术能够对心动周期中心肌弹性的变化进行无创且具有时间分辨力的测量。为此，通过前胸壁在人体心脏中诱发了24.3Hz的低频剪切振动。使用心电图（ECG）触发的稳态MRE序列，以每个振动周期八幅图像的帧率捕捉剪切振荡。在六名健康志愿者中，通过心脏短轴在两个成像平面中观察了二维剪切波场的时间演变。相关性分析表明，波幅与心跳同步调制，舒张期的波幅比收缩期高2.45±0.18（个体间平均值±标准差）。波幅的降低在收缩期开始时左心室直径变化之前75±9毫秒就已开始。使用线性弹性本构模型对这种波幅变化进行分析，结果显示在心动周期中心肌壁刚度的最大变化系数为37.7±10.6。
