Advancements in Quantitative Bound and Pore Water MR Imaging Method for Bone Fracture Risk Evaluation

Abstract

Bone fragility is a widespread problem worldwide and the current clinical standard diagnosis method for evaluating bone fragility through Bone Mineral Density (BMD) is not always effective in predicting bone fracture risk. Magnetic resonance imaging (MRI) has shown promise to provide complimentary diagnostics of bone fracture risk by assessing the tissue components of cortical bone. The concentrations of collagen-bound water (Cbw) and pore water (Cpw) can be quantified using MRI with an Adiabatic Inversion Recovery (AIR) sequence and a Double Adiabatic Full Passage (DAFP) sequence, respectively. These two components have also been shown to be predictive of many mechanical properties of cortical bone. This dissertation presents an effort to enhance the performance and applications of MRI methods in quantifying the bone water components with the goal of improving bone fracture risk evaluation. First, MRI-based finite element models of cadaver radii were generated with tissue material properties derived from 3D maps of Cbw and Cpw to investigate the effect of Cbw and Cpw on the evaluation of bone mechanical properties. It was demonstrated that these MRI-derived measures of Cbw and Cpw could improve the prediction of bone mechanical properties and have the potential to be useful in assessing patient-specific bone fragility risk. Next, the spectroscopic relaxometry measurements of cortical bone specimens were analyzed to improve the accuracy of Cbw and Cpw quantification. Finally, the method was applied to the imaging of lumbar vertebra samples with the aim to extend the utility of the bound and pore water imaging to different bone sites. In summary, this dissertation presents a new method to improve the prediction of bone fracture risk using MRI-derived bound water and pore water imaging.