Quantifying cortical bone free water using short echo time (STE-MRI) at 1.5 T.

Area of Science:

• Biomedical Engineering
• Radiology
• Bone Biology

Background:

• Cortical bone water content influences bone mechanical properties.
• Accurate quantification of free water in cortical bone is crucial for understanding bone health.
• Existing methods for bone water quantification have limitations.

Purpose of the Study:

• To establish and validate a Dual-TR Short Echo Time (STE) Magnetic Resonance (MR) protocol for clinical quantification of cortical bone free water at 1.5T.
• To compare MR-derived free water quantification with established dehydration techniques.
• To assess the correlation of bone water biomarkers with age in a healthy population.

Main Methods:

• Utilized a Dual-TR STE-MR imaging protocol to quantify cortical bone free water T1 (T1free) and concentration (ρfree).
• Validated the MR technique against dehydration in seven bovine cortical bone samples, using Bland-Altman analysis for agreement.
• Applied the validated technique to thirty healthy volunteers and examined the association between ρfree, T1free, and age.

Main Results:

• Mean ρfree values were 4.37% (STE-MR) and 5.34% (dehydration) for bovine bone, with good agreement (0.99% bias).
• Strong correlations were observed between ρfree and age (r² = 0.62) and T1free and age (r² = 0.8).
• The method demonstrated high reproducibility with an intra-class correlation of 0.95.

Conclusions:

• Dual-TR STE-MR imaging serves as a viable clinical tool for quantifying cortical bone free water concentration (ρfree) and T1 (T1free).
• The MR technique provides reliable and reproducible results comparable to dehydration methods.
• This imaging approach can be used to study age-related changes in cortical bone water content.