Quantifying Human Cortical Bone Bound and Free Water in vivo from Ultrashort Echo-Time MRI: A Model-Based Approach

Abstract

Objective: To quantify free and bound water components of cortical bone with a model-based numeric approach with use of ultrashort echo time (UTE) magnetic resonance (MR) imaging in vivo in order to introduce a new predictor for age related deterioration of cortical bone structure.
Results: The mean free water concentration, bound water concentration, free water T1, and bound water T1 in the recruited population were 5.9%, 19.6%, 306.79 msec, and 162.47 msec, respectively. All reported values were in good agreement with those in the literature. Cortical bone free water T1 (R2 = 0.72) and cortical bone free water concentration (R2 = 0.62) showed strong positive correlations with age.
Conclusion: The cortical bone free water concentration and free water T1 derived with UTE imaging are good predictors of agerelated deterioration of cortical bone structure and are potentially superior to previously introduced measures such as bone water concentration and suppression ratio.