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

Objectives

To evaluate the technical feasibility and applicability of quantitative MR techniques (delayed gadolinium-enhanced MRI of cartilage (dGEMRIC), T2 mapping, T2* mapping) at 7 T MRI for assessing hip cartilage.

Methods

Hips of 11 healthy volunteers were examined at 7 T 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 (T1_Gd; 0.2 mmol/kg Gd-DTPA^2? followed by 0.5 h of walking and 0.5 h of rest) for dGEMRIC. Relaxation times of cartilage were measured manually in 10 regions of interest. Pearson’s correlations between R1_delta?=?1/T1_Gd???1/T1₀ and T1_Gd 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.

Results

High correlations were found between R1_delta and T1_Gd 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).

Conclusions

T1, T2 and T2* mapping 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.

Key Points

? 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.