Validation of quantitative bound- and pore-water imaging in cortical bone.

PURPOSE To implement and validate a previously proposed ultra-short echo time method for measuring collagen-bound- and pore-water concentrations in bone based on their T2 differences. METHODS Clinically compatible ultra-short echo time image sequences for quantitative T2 -based bound and pore-water imaging in bone were implemented and validated on a 3T human scanner and a 4.7T small bore system. Bound- and pore-water images were generating using T2 -selective adiabatic pulses. In both cases, the magnetization preparation was integrated into a three-dimensional ultra-short echo time acquisition, with 16 radial spokes acquired per preparation. Images were acquired from human cadaveric femoral mid-shafts from which isolated bone samples were subsequently extracted for nonimaging analysis using T2 spectroscopic measurements. RESULTS A strong correlation was found between imaging-derived concentrations of bound and pore water and those determined from the isolated bone samples. CONCLUSIONS These studies demonstrate the translation of the previously developed approaches for distinguishing bound and pore water from human cortical bone using practical human MRI constraints of gradient performance and radiofrequency power deposition.