Voxel-based mapping of five MR biomarkers in the wrist bone marrow.

OBJECTIVE: MRI is a reliable and accurate technique to characterize rheumatoid arthritis. The aim of this study was to provide voxel-by-voxel 3D maps of the proton density fat fraction (PDFF), the T1 of water (T1W), the T1 of fat (T1F), the T2* of water (T2*W), the T2* of fat (T2*F) in the wrist bone marrow. MATERIALS AND METHODS: The experiments were conducted on 14 healthy volunteers (mean age: 24 ± 4). The data were acquired at 1.5 T using two optimized four-echo 3D 1.2 × 1.2 × 1.2 mm3-isotropic spoiled gradient sequences. A repeatability study was carried out. The measurements were done using a homemade parametric viewer software. RESULTS: The inter-volunteer results were, on average: PDFF = 86 ± 3%, T1W = 441 ± 113 ms, T1F = 245 ± 19 ms, T2*W = 6 ± 1 ms and T2*F = 16 ± 3 ms. The coefficients of variation were for fat based biomarkers CVPDFF < 5%, CVT1F < 15% and CVT2*F < 10% in the repeatability study. DISCUSSION: The protocol and quantification tool proposed in this study provide high-resolution voxel-by-voxel 3D maps of five biomarkers in the wrist in less than 4 min of acquisition.