Cross-relaxation times of normal and biochemically induced osteoarthritic rabbit knee cartilages

Abstract

We measured the spin-lattice relaxation times (T1) of water protons and intermolecular cross-relaxation times (T(IS)) from irradiated protein protons (f2-irradiation at 1.95 or -4.00 ppm) of rabbit normal and monoiodoacetate-induced degenerated knee articular cartilages to observed water protons. The mean values of T1 (T̄1) for control and degenerated rabbit knee cartilages were 1.87 ± 0.15 (mean ± SD, n = 29) and 1.82 ± 0.13s (n = 34), respectively. The mean values of water content (W̄(H2O)) for control and degenerated rabbit knee cartilages were 82.9 ± 2.09 (n = 26) and 83.1 ± 2.57% (n = 28), respectively. These values were not statistically different from each other. However, the mean values of T(IS) (T̄(IS)) for normal knee articular cartilage were significantly different from those for degenerated cartilage: (normal), T̄(IS) (f2=1.95 ppm) = 2.46 ± 0.62 s (n = 28), T̄(IS) (f2 = -4.00 ppm) = 4.25 ± 1.26 s (n = 26); (degenerated), T̄(IS) (f2 = 1.95 ppm) = 1.99 ± 0.76 s (n = 34), T̄(IS) (f2= -4.00 ppm) = 3.33 ± 0.76 s (n = 31). Obtained results may be attributed to the reported switchover from type II to type I collagen syntheses in osteoarthritic cartilage, resulting in broad collagen fibers. This specificity of cross-relaxation effect may prove useful in the noninvasive and pathophysiological evaluation of cartilage tissues in vivo.