There’s more to bone than just hard minerals like calcium. “Soft” components like collagen and collagen-bound water comprise more than half of bone’s content and are important for bone strength. X-ray based diagnostic tests (like CT and DXA – or “DEXA” – scans), which are used to assess bone strength and density, are sensitive only to the mineral portion of bone; the soft components are essentially invisible.
, and colleagues investigated the utility of nuclear magnetic resonance (NMR) signals – the basis for MRI scans – for assessing the mechanical properties of bone samples from cadavers. They found that NMR signals were better predictors of several measures of bone strength than X-ray derived signals like DXA.
Although standard clinical MRI scanners do not detect the exact NMR signals used in this study, the results, reported , suggest that if these measures are implemented on clinical scanners, MRI scans could provide a more complete assessment of fracture risk than X-ray based tests.