Change of Diffusion Tensor Imaging Parameters in Articular Cartilage With Progressive Proteoglycan Extraction

Abstract

Mean diffusivity evidence by the ADC is linearly correlated to progressive PG extraction in articular cartilage. FA and the first eigenvector seem to be specific to the collagen architecture of cartilage. DTI has the potential to become a valuable biomarker for the workup of cartilage degeneration in osteoarthritis, since evaluation of the PG content and collagen architectural properties of cartilage can be performed with a single, non–contrast-enhanced proton-based MRI measurement.

Ultra-high field diffusion tensor imaging of articular cartilage correlated with histology and scanning electron microscopy

“…The highly ordered structure of the collagen matrix is expected to induce anisotropy in the diffusivity of water, so that measuring the anisotropy of diffusion could give direct information on the integrity of the collagen matrix [6,7]. Also, diffusion tensor imaging (DTI) may be sensitive to the PG content through mean diffusivity [2,[8][9][10][11][12]. Therefore, diffusion tensor imaging (DTI) appears a promising technique for the diagnostic workup of articular cartilage, especially since it may be sensitive to both PG content and collagen fiber architecture.…”

“…Complete PG depletion resulted in increased apparent diffusion coefficients (ADC) [2,[8][9][10][11][12] but unchanged fractional anisotropy (FA) [10][11][12] and EV [10,12], thus indicating a dependence of ADC on the PG content and a dependence of FA and EV on the collagen architecture. Under loading conditions, changes in the cartilage matrix lead to changes in ADC, FA, and the EV orientation [13,14].…”

Techniques and applications of in vivo diffusion imaging of articular cartilage

“…Histology with safranin-O (for GAG estimation) and picrosirius red (to assess the orientation of the collagen architecture with polarized light microscopy [PLM]) were available before and after cartilage treatment with trypsin. Raya et al (24) found a significant correlation between the MD and the GAG loss as measured from safranin-O slices (r 2 =0.86, P<0.007). FA and first eigenvector as well as PLM showed only small changes in the order of magnitude of measurement errors, not correlating with PG loss.…”

“…More recently, Raya et al (24) analyzed the effect in the DTI parameters of progressive GAG depletion (Fig. 5).…”

“…The key idea behind the use of DTI is that the various components of the cartilage matrix have different effects on the motion of water molecules (20). The collagen network favors the motion of water along the collagen fibers inducing anisotropy in the motion of water, which can be measured with fractional anisotropy (FA) (20)(21)(22)(23)(24)(25)(26)(27). PG molecules, on the other hand, do not show a preferred orientation and therefore restrict the motion of water molecules equally in all directions.…”