Evaluation of articular cartilage in knee osteoarthritis using hybrid multidimensional MRI

To evaluate a two-compartment model with a normal and an abnormal compartment using hybrid multidimensional (HM) magnetic resonance imaging (MRI) for detection of early stage degeneration in knee articular cartilage.Forty mild osteoarthritis (OA; Kellgren-Lawrence grades [KLGs] 1 and 2), 27 moderate OA (KLG 3), and 23 healthy controls were included in the study. HM imaging using a two-compartment model was used to measure a normal and an abnormal cartilage compartment. The relationship between Vnormal and the degree of cartilage degeneration was examined using whole-organ MRI scores (WORMS). Receiver operating characteristic analysis was used to detect the ability of Vnormal, apparent diffusion coefficient (ADC), and T2 relaxation time to discriminate healthy controls from early OA.The intra- and interobserver reproducibility for calculated mean Vnormal values and WORMS indicated substantial agreement (intraclass correlation coefficient and weighted kappa >0.8). Overall, Vnormal in all compartments significantly differed among the healthy controls (50 ± 5.5%) and mild (41.1 ± 5.3%) and moderate OA (36.4 ± 8.1%). Mean Vnormal correlated negatively with the degree of OA progression (ρ = -0.778, p<0.001). Mean Vnormal was characterised by a higher sensitivity (82.5%, 95% confidence interval [CI = 67.2-92.7) and specificity (87%, 95% CI = 66.4-97.2), with a cut-off value of 44.4%, compared to ADC and T2 values or a combination of ADC and T2 to differentiate early OA from healthy controls.HM-MRI coupled with values of ADC and T2 may provide value for detecting cartilage degeneration at an early stage of OA.