Diffusion tensor MRI of myocardial fibers and sheets: Correspondence with visible cut‐face texture

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Abstract
Purpose To test the hypothesis that the primary, secondary, and tertiary eigenvectors of the diffusion tensor (DT) measured with DT-MRI correspond to the fiber, sheet, and sheet normal directions, respectively, we compared DT-MRI data with the texture visible in the cut face of fresh bovine myocardium. Materials and Methods DT-MRI and optical images obtained under identical conditions were compared objectively. Ink prints were made of the cut tissue, and the local orientations within these images were defined by analysis of local autocorrelations for regions matching DT-MRI pixels. Deviation angles between the cleavage orientations and the diffusion eigenvectors were analyzed in eight specimens sliced in three orthogonal planes. Results Root-mean-square (RMS) angular disparity was 11° between the first eigenvectors of the DT and the fiber direction, 14° between the second eigenvector and the sheet direction, 14° between the third eigenvector and the sheet normal direction, and 15° between the tensor orientation in the imaging plane and the cleavage orientation of the cut face. Conclusion The results support a parallel relationship between the eigenvectors of the DT and symmetry axes of the myocardial architecture. Specifically, the first, second and third eigenvectors correspond to the fiber, sheet, and sheet normal directions, respectively. J. Magn. Reson. Imaging 2003;17:31–42.