Reproducibility of in vivo magnetic resonance imaging T 1 rho and T 2 relaxation time measurements of hip cartilage at 3.0T in healthy volunteers

Abstract : PurposeTo assess the T1ρ and T2 values in the hip cartilage of healthy volunteers and to evaluate the reproducibility of these measurements.Materials and MethodsThe right hip joint of 30 asymptomatic volunteers was explored with 3T magnetic resonance imaging (MRI). Quantitative 3D T1ρ- and T2-maps sequences were repeated twice with a 30-minute delay (immediate reproducibility). The same protocol was repeated 14 days later (short-term reproducibility). Immediate and short-term reproducibility were estimated using coefficients of variation and correlation concordance coefficients (CCC). The precisions of the measurements were estimated by the ratio of the standard deviations. A mixed linear model was used to analyze the effect of patient's characteristics on T1ρ and T2 values.ResultsImmediate reproducibility was significantly better than short-term reproducibility for T1ρ (CCC of 0.75 versus 0.55; P = 0.007) and T2 (CCC 0.65 versus 0.32; P < 0.001). The precisions of the measurements were estimated between 5.5% and 9.1%. Median T1ρ values were 6.0 msec higher in women than in men (P = 0.006), with no significant influence of age, body mass index (BMI), or sports activity. Median T2 values were not significantly different between men and women (0.4 msec lower in women; P = 0.76). There was no significant influence of age, BMI, or sports activity. T1ρ and T2 values were lower in lateral regions than in medial regions (4.9 msec and 2.5 msec lower respectively; P < 0.0001).ConclusionImmediate reproducibility of T1ρ and T2 values is better than short-term, with limited effect of 30 minutes decubitus. T1ρ values are significantly higher in women.Level of Evidence: 2Technical Efficacy: Stage 2