Knee cartilage T2 characteristics and evolution in relation to morphologic abnormalities detected at 3-T MR imaging: a longitudinal study of the normal control cohort from the Osteoarthritis Initiative.

Abstract

To determine the frequency of degenerative knee morphologic abnormalities in asymptomatic individuals by using 3-T magnetic resonance (MR) imaging and to investigate the characteristics and evolution of cartilage T2 values in relation to morphologic abnormalities with a longitudinal study. The study was approved by the institutional review board and was compliant with HIPAA. Ninety-five asymptomatic subjects aged 45-78 years who were free of risk factors for osteoarthritis (OA) were selected from the Osteoarthritis Initiative normal control cohort and examined with radiography and 3-T MR imaging. Data obtained at both baseline and 2-year follow-up were analyzed. OA-related knee abnormalities were analyzed by using the whole-organ MR imaging score (WORMS). Cartilage T2 maps were generated by using sagittal two-dimensional multiecho spin-echo images of the right knee. Statistical significance was determined with the Student t test, the paired t test, a mixed random effects model, one-way analysis of variance, and a multiple linear regression model. Knee abnormalities were identified with a high frequency (90% at baseline and 92% at 2-year follow-up). The prevalence of hyaline cartilage lesions was particularly high (86% at baseline and 84% at follow-up). A significant longitudinal increase in T2 was detected in the tibiofemoral cartilage but not the patellofemoral cartilage (P = .0072). The longitudinal change in T2 was significantly associated with worsening of the cartilage WORMS (P = .038). Asymptomatic subjects have a high frequency of OA-related morphologic abnormalities. A significant increase in tibiofemoral cartilage T2 was detected over the 2-year period. A greater increase in T2 was associated with increased progression of cartilage morphologic abnormalities.