The Relationship between MR Parameters and Biomechanical Quantities of Loaded Human Articular Cartilage in Osteoarthritis: An In-Vitro Study

Abstract

The aim of this study was to assess the changes in MRI parameters during applied load directly in MR scanner and correlate these changes with biomechanical parameters of human articular cartilage. Cartilage explants from patients who underwent total knee replacement were examined in the micro-imaging system in 3T scanner. Respective MRI parameters (T 1 without-and T 1 with contrast agent as a marker of proteoglycan content, T 2 as a marker of collagen network anisotropy and ADC as a measure of diffusivity) were calculated in pre-and during compression state. Subsequently, these parameters were compared to the biomechanical properties of articular cartilage, instantaneous modulus (I), equilibrium modulus (Eq) and time of tissue relaxation (τ). Significant load-induced changes of T 2 and ADC were recorded. High correlation between T1Gd and I (r = 0.6324), and between ADC and Eq (r = -0.4884) was found. Multi-parametric MRI may have great potential in analyzing static and dynamic biomechanical behavior of articular cartilage in early stages of osteoarthritis (OA).

SNR‐weighted regularization of ADC estimates from double‐echo in steady‐state (DESS)

“…The ADC of cartilage has been measured in high-field MRI experiments as 1.6·10 −3 mm 2 /s in vivo at field strengths of 1.5T-3T [9, 10, 11], with slightly lower values in vitro [12, 13]. It has also been shown to be almost twice as large at the articular surface compared to the bone-cartilage interface [14, 15]. Furthermore, elevated ADC has been measured in OA-affected cartilage by about 25% [16].…”