Maier S E, Fischer S E, McKinnon G C, Hess O M, Krayenbuehl H P, Boesiger P
Institute of Biomedical Engineering and Medical Informatics, University of Zurich, Switzerland.
Circulation. 1992 Dec;86(6):1919-28. doi: 10.1161/01.cir.86.6.1919.
Segmental wall motion was assessed noninvasively in eight patients with hypertrophic cardiomyopathy and six healthy volunteers by magnetic resonance myocardial tagging.
Localization scans were performed for determination of the true short-axis views of the left ventricle (double-angulated view). Spatial modulation of magnetization was used to produce a rectangular grid of landmarks. Distortion of the grid was assessed at end diastole, mid systole, and end systole with multiphase gradient echoes. Image sets were acquired at three different planes, namely, the base, the equator, and the apex. Quantitative evaluation was carried out by computer-assisted image analysis. Each individual grid crossing point was identified automatically and the displacement calculated. A polar coordinate system with the center of gravity as motion reference point was chosen to assess fractional rotation and radial displacement at the endocardial, midwall, and epicardial layers of the septal, anterior, posterior, and inferior regions. A wringing motion of the left ventricle with a clockwise rotation of 5.0 +/- 2.4 degrees at the base and a counterclockwise rotation of -9.6 +/- 2.9 degrees at the apex was observed in control subjects. An equal rotation of 5.0 +/- 2.5 degrees at the base and a slightly reduced rotation of -7.3 +/- 5.2 degrees at the apex was found in patients with hypertrophic cardiomyopathy. A transmural gradient in fractional rotation and radial displacement was observed, with the highest values in the endocardial layer. Rotation in patients with hypertrophic cardiomyopathy was significantly less than in normal volunteers in the posterior region of the equatorial and apical planes. Furthermore, radial displacement was significantly reduced in the septum and inferior wall. In the anterior and posterior wall segments, a reduction of the radial displacement was observed only in the epicardium and midwall layers.
Magnetic resonance myocardial tagging allows the noninvasive assessment of regional wall motion. Both in normal volunteers and in patients with hypertrophic cardiomyopathies, cardiac motion occurs in a complex mode, with the base and the apex rotating in opposite directions and the equatorial plane as a transitional zone (wringing motion). A reduced cardiac rotation can be observed in patients with hypertrophic cardiomyopathy mainly in the posterior region, whereas a reduced radial displacement is found in the inferior septal zone.
通过磁共振心肌标记技术对8例肥厚型心肌病患者和6名健康志愿者进行了节段性室壁运动的无创评估。
进行定位扫描以确定左心室的真正短轴视图（双角度视图）。利用磁化强度的空间调制产生一个地标矩形网格。在舒张末期、收缩中期和收缩末期用多相梯度回波评估网格的变形情况。在三个不同平面，即心底、心尖和心腰部采集图像集。通过计算机辅助图像分析进行定量评估。自动识别每个网格交叉点并计算位移。选择以重心为运动参考点的极坐标系来评估间隔、前壁、后壁和下壁的心内膜、中层和心外膜层的分数旋转和径向位移。在对照受试者中观察到左心室呈拧绞样运动，心底顺时针旋转5.0±2.4度，心尖逆时针旋转-9.6±2.9度。肥厚型心肌病患者心底旋转角度为5.0±2.5度，与对照受试者相同，心尖旋转角度略有减小，为-7.3±5.2度。观察到分数旋转和径向位移存在跨壁梯度，在心内膜层值最高。肥厚型心肌病患者在赤道平面和心尖平面后壁区域的旋转明显低于正常志愿者。此外，间隔和下壁的径向位移明显减小。在前壁和后壁节段，仅在心外膜和中层观察到径向位移减小。
磁共振心肌标记技术可对局部室壁运动进行无创评估。无论是正常志愿者还是肥厚型心肌病患者，心脏运动都以复杂模式发生，心底和心尖向相反方向旋转，赤道平面为过渡区（拧绞样运动）。肥厚型心肌病患者主要在心后壁区域可观察到心脏旋转减小，而在下间隔区域可发现径向位移减小。
