Henry H. Ong1, Alexander C. Wright1, Felix W. Wehrli1
1Laboratory for Structural NMR Imaging, Department of Radiology, University of Pennsylvania School of Medicine, Philadelphia, PA, United States
Magnetic resonance is a powerful tool for non-destructive study of bone water, which can provide insight into bone micro- and nanostructure. However, the MR signal of bone is comprised of several proton populations including collagen-associated water, and water within the pore space (Haversian and lacuno-canalicular system). We hypothesize that water in pores is predominantly free and water in the bone matrix is predominantly associated with collagen. Using 2H exchange and inversion recovery experiments, we estimated porosity in human cortical bone and found it to agree with micro-CT based volumetric measurements with a significant fraction being collagen-associated.