Multinuclear solid-state three-dimensional MRI of bone and synthetic calcium phosphates

Multinuclear three-dimensional solid-state MRI of bone, tooth, and syntheti c calcium phosphates is demonstrated in vitro and in vivo with a projection reconstruction technique based on acquisition of free induction decays in the presence of fixed amplitude magnetic field gradients. Phosphorus-31 sol id-state MRI provides direct images of the calcium phosphate constituents o f bone substance and is a quantitative measurement of the true volumetric b one mineral density of the bone. Proton solid-state MRI shows the density o f bone matrix including its organic constituents, which consist principally of collagen. These solid-state MRI methods promise to yield a biological p icture of bone richer in information concerning the bone composition and sh ort range-crystalline order than the fluid-state images provided by convent ional proton MRI or the density images produced by radiologic imaging techn iques. Three-dimensional solid-state projection reconstruction MRI should b e readily adaptable to both human clinical use and nonmedical applications for a variety of solids in materials science.