Diffusion tensor microscopy of the intervertebral disc anulus fibrosus

Morphologically accurate biomechanical models of the intervertebral disc an ulus fibrosus (AF) require precise knowledge of its lamellar architecture; however, available methods of assessment are limited by poor spatial resolu tion or the destructive nature of the technique. In a novel approach, diffu sion tensor microscopy was used in this study to characterize the microstru cture of excised porcine AF samples. Results show diffusion in the AF to be anisotropic. The orientations of anisotropy exhibit a layered morphology t hat agrees with light micrographs of the corresponding samples, and the beh avior of the orientation angles is consistent with the known AF collagen fi ber architecture. A static magnetic field dependent relaxation anisotropy w as observed in the AF, which has methodological implications for magnetic r esonance (MR) imaging of ordered collageneous tissues. These findings prese nt MR diffusion tensor microscopy as a potentially valuable tool to assess quantitatively and nondestructively water diffusion anisotropy and lamellar structure of the intervertebral disc AF. Magn Reson Med 41:992-999, 1999. (C) 1999 Wiley-Liss, Inc.