Voxel-based mapping of five MR biomarkers in the wrist bone marrow
Résumé
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 T of water (T), the T of fat (T), the T* of water (T*), the T* of fat (T*) 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 mm-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%, T = 441 ± 113 ms, T = 245 ± 19 ms, T* = 6 ± 1 ms and T* = 16 ± 3 ms. The coefficients of variation were for fat based biomarkers CV < 5%, CV < 15% and CV < 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.