Texture analysis of cartilage T-2 maps: individuals with risk factors for OA have higher and more heterogeneous knee cartilage MR T-2 compared to normal controls - data from the osteoarthritis initiative

Introduction: The goals of this study were (i) to compare the prevalence of focal knee abnormalities, the mean cartilage T-2 relaxation time, and the spatial distribution of cartilage magnetic resonance (MR) T-2 relaxation times between subjects with and without risk factors for Osteoarthritis (OA), (ii) to determine the relationship between MR cartilage T-2 parameters, age and cartilage morphology as determined with whole-organ magnetic resonance imaging scores (WORMS) and (iii) to assess the reproducibility of WORMS scoring and T-2 relaxation time measurements including the mean and grey level co-occurrence matrix (GLCM) texture parameters. Methods: Subjects with risk factors for OA (n = 92) and healthy controls (n = 53) were randomly selected from the Osteoarthritis Initiative (OAI) incidence and control cohorts, respectively. The specific inclusion criteria for this study were (1) age range 45-55 years, (2) body mass index (BMI) of 19-27 kg/m(2), (3) Western Ontario and McMaster University (WOMAC) pain score of zero and (4) Kellgren Lawrence (KL) score of zero at baseline. 3.0 Tesla MR images of the right knee were analyzed using morphological gradings of cartilage, bone marrow and menisci (WORMS) as well as compartment specific cartilage T-2 mean and heterogeneity. Regression models adjusted for age, gender, and BMI were used to determine the difference in cartilage parameters between groups. Results: While there was no significant difference in the prevalence of knee abnormalities (cartilage lesions, bone marrow lesions, meniscus lesions) between controls and subjects at risk for OA, T-2 parameters (mean T-2, GLCM contrast, and GLCM variance) were significantly elevated in those at risk for OA. Additionally, a positive significant association between cartilage WORMS score and cartilage T-2 parameters was evident. Conclusions: Overall, this study demonstrated that subjects at risk for OA have both higher and more heterogeneous cartilage T-2 values than controls, and that T-2 parameters are associated with morphologic degeneration.