Bone marrow fat quantification of osteoporotic vertebral compression fractures: comparison of multi-voxel proton MR spectroscopy and chemical-shift gradient-echo MR imaging

Background: Only a few studies have used in/opposed phase method for a quantitative evaluation of fat fraction in the spine. Purpose: To compare multivoxel proton MR spectroscopy and chemical-shift gradient-echo MR imaging for bone marrow fat quantification in vertebral compression fractures (VCF). Material and Methods: Vertebral marrow fat quantification in fifteen patients was measured at 3.0-T. Multivoxel proton spectroscopy (MRS) and in/opposed-phase MR imaging using a fat map build with a triple-echo gradient-echo sequence was used. All the patients had benign vertebral collapse. Bone marrow fat content was evaluated by both techniques in compressed (acute or chronic) and in non-compressed vertebrae. Results: The percentage of fat fraction measured by the triple-echo sequence was well correlated with those calculated by MRS (r(2) = 0.85; P < 10(-4)). There was a significant decrease of fat fraction in acute VCF versus both chronic VCF (P < 10(-9)) and non-fractured vertebrae (P < 10(-7)). There was no significant difference in fat fraction evaluated by both techniques between non-fractured vertebrae and chronic VCF. Conclusion: We have validated the in/opposed phase method compared with MRS for vertebral bone marrow fat quantification. The fat mapping using a triple-echo gradient-echo sequence allows distinguishing acute and chronic benign VCF.