Spiegel Marcus A, Luechinger Roger, Schwitter Jueg, Boesiger Peter
Institute for Biomedical Engineering, University and ETH, Zurich, Switzerland.
Invest Radiol. 2003 Oct;38(10):669-78. doi: 10.1097/01.rli.0000084888.79706.3a.
Although endocardial ejection indexes lead to overestimation of contractility in hypertrophied hearts, circumferential fiber shortening at the mid wall (cFS) is less affected by wall thickness. In this study magnetic resonance tagging is exploited to assess directly cFS in normal and hypertrophied hearts.
A novel tagging procedure generates freely definable, convex ring saturation bands. Data acquisition during the cardiac cycle is achieved with a fast, single breath-hold echo-planar imaging measurement that is combined with a slice-following approach and a navigator-guided breath-holding technique to improve reproducibility of breath hold positions.
The procedure is able to create variably shaped convex saturation structures on the myocardium that can be tracked automatically throughout the cardiac cycle. Circumferential shortening at the endocardial border (FSendo) obtained in 6 healthy volunteers and in 6 patients with hypertensive cardiomyopathy suggested hypercontractility of hypertrophied hearts (30.7 +/- 4.1% vs. 43.9 +/- 4.4% respectively; P < 0.002), whereas shortening at the level of the myofibers assessed as cFS was not different (17.2 +/- 1.4% vs. 18.1 +/- 2.8% respectively; P = 0.49).
The presented approach allows for assessment of midwall myocardial mechanics and may become a useful tool to study contractile function in hypertrophied hearts.
尽管心内膜射血指数会导致对肥厚心脏收缩力的高估，但中壁圆周纤维缩短（cFS）受壁厚的影响较小。在本研究中，利用磁共振标记直接评估正常和肥厚心脏中的cFS。
一种新颖的标记程序可生成可自由定义的凸环形饱和带。通过快速单屏气回波平面成像测量实现心动周期中的数据采集，该测量与切片跟踪方法和导航器引导的屏气技术相结合，以提高屏气位置的可重复性。
该程序能够在心肌上创建形状可变的凸饱和结构，这些结构可在整个心动周期中自动跟踪。在6名健康志愿者和6名高血压性心肌病患者中获得的心内膜边界处的圆周缩短（FSendo）表明肥厚心脏存在收缩亢进（分别为30.7±4.1%和43.9±4.4%；P<0.002），而作为cFS评估的肌纤维水平处的缩短无差异（分别为17.2±1.4%和18.1±2.8%；P = 0.49）。
所提出的方法可用于评估中壁心肌力学，可能成为研究肥厚心脏收缩功能的有用工具。
