Longitudinal evaluation of T1ρ and T2 spatial distribution in osteoarthritic and healthy medial knee cartilage

Objective: To investigate longitudinal changes in laminar and spatial distribution of knee articular cartilage magnetic resonance imaging (MRI) T-1p and T-2 relaxation times, in individuals with and without medial compartment cartilage defects. Design: All subjects (at baseline n = 88, >18 years old) underwent 3-Tesla knee MRI at baseline and annually thereafter for 3 years. The MR studies were evaluated for presence of cartilage defects (modified Whole-Organ Magnetic Resonance Imaging Scoring - mWORMS), and quantitative T-1 rho and T-2 relaxation time maps. Subjects were segregated into those with (mWORMS >= 2) and without (mWORMS <= 1) cartilage lesions at the medial tibia (MT) or medial femur (MF) at each time point. Laminar (bone and articular layer) and spatial (gray level co-occurrence matrix - GLCM) distribution of the T-1 rho and T-2 relaxation time maps were calculated. Linear regression models (cross-sectional) and Generalized Estimating Equations (GEEs) (longitudinal) were used. Results: Global T-1 rho, global T-2 and articular layer T-2 relaxation times at the MF, and global and articular layer T-2 relaxation times at the MT, were higher in subjects with cartilage lesions compared to those without lesions. At the MT global T-1 rho relaxation times were higher at each time point in subjects with lesions. MT T-1 rho and T-2 became progressively more heterogeneous than control compartments over the course of the study. Conclusion: Spatial distribution of T-1 rho and T-2 relaxation time maps in medial knee OA using GLCM technique may be a sensitive indicator of cartilage deterioration, in addition to whole-compartment relaxation time data. (C) 2013 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.