Quantification of cartilage biomechanical and biochemical properties via T1ρ magnetic resonance imaging

Abstract

The aim of this study is to develop T_1ρ as an MR marker of the compositional and functional condition of cartilage. Specifically, we investigate the correlation of changes in cartilage biomechanical and biochemical properties with T_1ρ relaxation rate in a cytokine‐induced model of degeneration. Bovine cartilage explants were cultured with 30 ng/mL of interleukin‐1β to mimic the cartilage degradation of early osteoarthritis. The average rate of T_1ρ relaxation was calculated from T_1ρ maps acquired on a 4.7 T research scanner. Stress‐relaxation biomechanical tests were conducted with a confined compression apparatus to measure uniaxial aggregate modulus (H_A) and hydraulic permeability (k₀) using linear biphasic theory. Proteoglycan, collagen, and water content were measured via biochemical assays. Average T_1ρ relaxation rate was strongly correlated with proteoglycan content (R² = 0.926), H_A (R² = 0.828), and log₁₀ k₀ (R² = 0.862). Results of this study demonstrate that T_1ρ MRI can detect changes in proteoglycan content and biomechanical properties of cartilage in a physiologically relevant model of cartilage degeneration. The T_1ρ technique can potentially be used to noninvasively and quantitatively assess the biochemical and biomechanical characteristics of articular cartilage in humans during the progression of osteoarthritis. Magn Reson Med, 2005.