Quantitative magnetic resonance arthrography in patients with femoroacetabular impingement

Purpose: Quantitative MRI (QMRI) of the hip with sequences such as T1_ρ and T2 mapping has been utilized to detect early changes in cartilage matrix composition. However, QMRI has not been performed in the presence of intra-articular contrast. Thus the purpose of this study was to evaluate the feasibility and use of QMRI during MR-arthrography (MRA) in femoracetabular impingement (FAI) patients. Materials and Methods: Using a 3 Tesla MR-scanner, 10 FAI patients underwent a unilateral MRA and standard MRI of the hip joint. Global and sub-regional T1_ρ and T2 relaxation times of the acetabular and femoral articular cartilage were computed in the MRA and MRI assessments and agreement of these values were assessed using the Krippendorff's alpha (α) coefficient and linear regression (μ). T1_ρ and T2 relaxation times between the MRA and MRI were compared using a repeated measures analysis of variance. Results: Both global and sub-regional T1_ρ and T2 relaxation times demonstrated strong agreement (α > 0.83; μ > 0.85) independent of intra-articular contrast. Also, global and sub-regional acetabular T1_ρ (P = 0.72) and T2 (P = 0.94), as well as femoral T1_ρ, relaxation times were similar between MRA and MRI (P = 0.73) yet femoral T2 relaxation times decreased when using intra-articular contrast (P = 0.04). Conclusion: This study demonstrated the feasibility of T1ρ and T2 mapping for use in hip MRA with FAI patients. The inclusion of QMRI in MRA provides a quantitative assessment of the effects of FAI on hip joint articular cartilage while allowing for detailed assessment of labral pathology with the use of intra-articular contrast. J. Magn. Reson. Imaging 2016;44:1539–1545.