Diffusion tensor microscopy of the intervertebral disc anulus fibrosus

Abstract

Morphologically accurate biomechanical models of the intervertebral disc anulus fibrosus (AF) require precise knowledge of its lamellar architecture; however, available methods of assessment are limited by poor spatial resolution or the destructive nature of the technique. In a novel approach, diffusion tensor microscopy was used in this study to characterize the microstructure of excised porcine AF samples. Results show diffusion in the AF to be anisotropic. The orientations of anisotropy exhibit a layered morphology that agrees with light micrographs of the corresponding samples, and the behavior of the orientation angles is consistent with the known AF collagen fiber architecture. A static magnetic field-dependent relaxation anisotropy was observed in the AF, which has methodological implications for magnetic resonance (MR) imaging of ordered collageneous tissues. These findings present 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. 1999 Wiley-Liss, Inc.

In vivo quantification of human lumbar disc degeneration using T1ρ-weighted magnetic resonance imaging

“…Similar quantitative imaging studies investigating intervertebral disc degeneration have been performed previously, including T 1 -and T 2 -weighted relaxation [4,8,11], magnetization transfer [27], diffusion imaging [3,15,18,21], and spectroscopy [19,22]. Some techniques, while appropriate for basic science research, are less suitable for clinical in vivo applications.…”

Magnetic resonance imaging and spectroscopy of the intervertebral disc

“…Quantitative T 1r imaging has been used in cartilage (31)(32)(33)(34)(35)(36)(37)(38)(39)(40)(41) and is affected by the interaction between motionally restricted water molecules and their macromolecular environment such as the glycosaminoglycan content. The extracellular matrix in the intervertebral disc may potentially be investigated using these techniques.…”

“…It was also shown that collagenase degradation of the nucleus slightly increased the apparent diffusion coefficient (ADC) (36). In a microscopic diffusion tensor study (37), at 7.1 T, using specimens of porcine annulus fibrosus, Hsu et al demonstrated diffusion anisotropy, which potentially could be related to the collagen fiber orientation.…”

Reconstruction and Quantification of Diffusion Tensor Imaging-Derived Cardiac Fibre and Sheet Structure in Ventricular Regions used in Studies of Excitation Propagation

“…Previously applied to trace fibre tracts in the central nervous system [26,40,50] and study structure in cartilage [37] and skeletal muscle [3], the primary eigenvector of the diffusion tensor has been validated as a measure of cardiac fibre orientation [33,36,53] and the secondary and tertiary eigenvectors have been proposed as indices [61] and validated as measures [29] of ventricular sheet structure.…”