ANISOTROPY OF WATER DIFFUSION IN THE MYOCARDIUM OF THE RAT
ANISOTROPY OF WATER DIFFUSION IN THE MYOCARDIUM OF THE RAT
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DOI：
10.1161/01.res.74.5.789
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发表时间：
1994-05-01
影响因子：
20.1
通讯作者：
KANTOR, HL
中科院分区：
文献类型：
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作者：
GARRIDO, L;WEDEEN, VJ;KANTOR, HL
脉冲场梯度核磁共振方法结合核磁共振成像，用于确定在37 ℃灌注大鼠心脏的水扩散各向异性。发现观察到的扩散系数D-app（表观扩散系数）取决于所施加的梯度g的取向。当g平行于心外膜表面时，观察到的扩散率为D-app平行于t =1.8+/-0.4x10（-9）m（2）s（-1），而当g垂直于t时，扩散率为D（app）垂直于t =2.5+/-0.5x10（-9）m（2）s（-1）。为了更好地表征这种方向依赖性，获得了心肌的二阶扩散张量D的图像。这些数据表明心肌结构的几个基本特征，包括纤维取向相对于心室轴的螺旋度和纤维节距角随透壁深度的变化。扩散各向异性可以通过扩散张量的本征值以与坐标无关的方式量化。在心肌中壁，这些特征值为E（1）=3.29+/-0.57，E（2）=2.01+/-0.42，E（3）=0.77+/-0.58x10（-9）m（2）s（-1）（平均值+/-SD）。这些数据表明，心肌水扩散基本上是不受限制的平行肌纤维。他们进一步表明，未能测量完整的扩散张量可能会导致大大低估心肌中的扩散各向异性。
Pulsed field gradient nuclear magnetic resonance methods combined with nuclear magnetic resonance imaging were used to determine the water diffusion anisotropy in perfused rat hearts at 37 degrees C. It was found that the observed diffusion coefficient D-app (apparent diffusion coefficient) depends on the orientation of the applied gradient g. When g is parallel to the epicardial surface, the observed diffusivity is D-app parallel to=1.8+/-0.4x10(-9) m(2) s(-1), whereas when g is perpendicular to it, diffusivity is D(app)perpendicular to=2.5+/- 0.5x10(-9) m(2) s(-1). To better characterize this directional dependence, images of the second-order diffusion tenser D of the myocardium were obtained. These data demonstrate several essential features of cardiac myoarchitecture, including the helicity of fiber orientation with respect to the ventricular axis and the variation of fiber pitch angle with transmural depth. Diffusion anisotropy may be quantified in a coordinate-independent manner by the eigenvalues of the diffusion tenser. In the myocardial midwall, these eigenvalues were E(1)=3.29+/-0.57, E(2)=2.01+/-0.42, and E(3)=0.77+/-0.58x10(-9) m(2) s(-1) (mean+/-SD). These data suggest that myocardial water diffusion is essentially unrestricted parallel to the myofibers. They further show that failure to measure the complete diffusion tenser may lead to substantial underestimates of diffusion anisotropy in the myocardium.