Feasibility of T2* Mapping for the Evaluation of Hip Joint Cartilage at 1.5T Using a Three-Dimensional (3D), Gradient-Echo (GRE) Sequence: A Prospective Study

This study defines the feasibility of utilizing three-dimensional (3D) gradient-echo (GRE) MRI at 1.5T for T-2* mapping to assess hip joint cartilage degenerative changes using standard morphological MR grading while comparing it to delayed gadolinium-enhanced MRI of cartilage (dGEMRIC). MRI was obtained from 10 asymptomatic young adult volunteers and 33 patients with symptomatic femoroacetabular impingement (FAI). The protocol included T-2* mapping without gadolinium-enhancement utilizing a 3D-GRE sequence with six echoes, and after gadolinium injection, routine hip sequences, and a dual-flip-angle 3D-GRE sequence for dGEMRIC T-1 mapping. Cartilage was classified as normal, with mild changes, or with severe degenerative changes based on morphological MRI. T-1 and T-2 findings were subsequently correlated. There were significant differences between volunteers and patients in normally-rated cartilage only for T-1 values. Both T-1 and T-2* values decreased significantly with the various grades of cartilage damage. There was a statistically significant correlation between standard MRI and T-2* (T-1) (P < 0.05). High intraclass correlation was noted for both T-1 and T-2*. Correlation factor was 0.860 to 0.954 (T-2*-T-1 intraobserver) and 0.826 to 0.867 (T-2*-T-1, interobserver). It is feasible to gather further information about cartilage status within the hip joint using GRE T-2* mapping at 1.5T. Magn Reson Med 62:896-901, 2009. (C) 2009 Wiley-Liss, Inc.