7 Tesla quantitative hip MRI: T1, T2 and T2* mapping of hip cartilage in healthy volunteers.

Abstract

To evaluate the technical feasibility and applicability of quantitative MR techniques (delayed gadolinium-enhanced MRI of cartilage (dGEMRIC), T2 mapping, T2* mapping) at 7T MRI for assessing hip cartilage. Hips of 11 healthy volunteers were examined at 7T MRI with an 8-channel radiofrequency transmit/receive body coil using multi-echo sequences for T2 and T2* mapping and a dual flip angle gradient-echo sequence before (T10) and after intravenous contrast agent administration (T1Gd; 0.2mmol/kg Gd-DTPA(2-) followed by 0.5h of walking and 0.5h of rest) for dGEMRIC. Relaxation times of cartilage were measured manually in 10 regions of interest. Pearson's correlations between R1delta = 1/T1Gd - 1/T10 and T1Gd and between T2 and T2* were calculated. Image quality and the delineation of acetabular and femoral cartilage in the relaxation time maps were evaluated using discrete rating scales. High correlations were found between R1delta and T1Gd and between T2 and T2* relaxation times (all p < 0.01). All techniques delivered diagnostic image quality, with best delineation of femoral and acetabular cartilage in the T2* maps (mean 3.2 out of a maximum of 4 points). T1, T2 and T2* mapping of hip cartilage with diagnostic image quality is feasible at 7T. To perform dGEMRIC at 7T, pre-contrast T1 mapping can be omitted. • dGEMRIC of hip cartilage with diagnostic image quality is feasible at 7 T. • To perform dGEMRIC at 7 T, pre-contrast T1 mapping can be omitted. • T2(*) mapping of hip cartilage with diagnostic image quality is feasible at 7 T. • T2 and T2* relaxation times of cartilage were highly correlated at 7 T. • Best delineation of femoral and acetabular cartilage was found in T2* maps.