Wedeen V J, Weisskoff R M, Reese T G, Beache G M, Poncelet B P, Rosen B R, Dinsmore R E
Department of Radiology, Massachusetts General Hospital, Boston, USA.
Magn Reson Med. 1995 Mar;33(3):401-8. doi: 10.1002/mrm.1910330313.
We present methods to acquire and analyze NMR movies of myocardial strain rates in which cardiac motion is suppressed and the histories of strain rates are accurately defined for each voxel of myocardial tissue. By means of stimulated echoes, the myocardial strain-rate tensor is phase-encoded at progressive delays in the cardiac cycle while the slice-select and spatial encoding of the image acquisition are performed at a constant cardiac delay. In these data, every image shows the identical myocardial tissue, and the anatomic configuration of the heart appears motionless. The myocardial strain-rate data, however, indicate the state of motion which existed in this slice at the time of the velocity phase-encoding, and these data evolve with the progressive delay as a movie. Using echo-planar MRI, motionless movies of myocardial strain rate of four to eight cardiac delays are obtained in a breath-hold. As an application, a quantitative characterization of cardiac mechanical synchrony is accomplished by principal component analysis (PCA) of the time series of strain rates.
我们提出了获取和分析心肌应变率核磁共振电影的方法，其中心脏运动被抑制，并且心肌组织的每个体素的应变率历史被精确界定。通过受激回波，心肌应变率张量在心动周期的渐进延迟中进行相位编码，而图像采集的层面选择和空间编码在恒定的心脏延迟下进行。在这些数据中，每幅图像都显示相同的心肌组织，心脏的解剖结构看起来静止不动。然而，心肌应变率数据表明了在速度相位编码时该层面存在的运动状态，并且这些数据随着渐进延迟像电影一样演变。使用回波平面磁共振成像，在一次屏气中可获得四到八个心脏延迟的心肌应变率静止电影。作为一种应用，通过对应变率时间序列进行主成分分析（PCA）实现了心脏机械同步性的定量表征。
