Quantifying Cortical Bone Free Water Using short echo time (STE-MRI) at 1.5T (2002.00209v1)

Abstract: Purpose: The purpose of our study was to use Dual-TR STE-MR protocol as a clinical tool for cortical bone free water quantification at 1.5T and validate it by comparing the obtained results (MR-derived results) with dehydration results. Methods: Human studies were compliant with HIPPA and were approved by the institutional review board. Short Echo Time (STE) MR imaging with different Repetition Times (TRs) was used for quantification of cortical bone free water T1 (T1free) and concentration (\r{ho}free). The proposed strategy was compared with the dehydration technique in seven bovine cortical bone samples. The agreement between the two methods was quantified by using Bland and Altman analysis. Then we applied the technique on a cross-sectional population of thirty healthy volunteers (18F/12M) and examined the association of the biomarkers with age. Results: The mean values of \r{ho}free for bovine cortical bone specimens were quantified as 4.37% and 5.34% by using STE-MR and dehydration techniques, respectively. The Bland and Altman analysis showed good agreement between the two methods along with the suggestion of 0.99% bias between them. Strong correlations were also reported between \r{ho}free (r2 = 0.62) and T1free and age (r2 = 0.8). The reproducibility of the method, evaluated in eight subjects, yielded an intra-class correlation of 0.95. Conclusion: STE-MR imaging with dual-TR strategy is a clinical solution for quantifying cortical bone \r{ho}free and T1free.

• The paper proposes a dual-TR STE-MR protocol validated against the dehydration technique for quantifying cortical bone free water at 1.5T in a clinical setting.
• The STE-MRI method showed strong agreement with dehydration (bias 0.99%) and high reproducibility (ICC 0.95), with free water parameters correlating significantly with age (ρ=0.62, T1=0.8).
• This clinical STE-MRI approach provides an accessible alternative to other methods, potentially enabling better monitoring of age-related bone quality and porosity changes relevant to conditions like osteoporosis.

Quantifying Cortical Bone Free Water Using STE-MRI at 1.5T

This paper introduces a clinical methodology for the quantification of cortical bone free water using short echo time magnetic resonance imaging (STE-MRI) at a magnetic field strength of 1.5 Tesla. The authors propose a Dual-TR STE-MR protocol and validate this method against the established dehydration technique.

Methodology

The paper employed STE-MRI with varying repetition times (TRs) to quantify cortical bone free water's longitudinal relaxation time (T1free) and concentration (ρfree). This approach was compared to the dehydration technique in bovine cortical bone samples, quantified by Bland and Altman analysis. Further, the methodology was applied to a cross-sectional sample of thirty healthy volunteers.

Results

The paper reports mean free water concentration values of 4.37% and 5.34% from STE-MRI and dehydration techniques, respectively, with a suggested bias of 0.99% between them. Comparative analysis showed strong agreement between these methods, and high reproducibility was noted, with an intra-class correlation coefficient of 0.95. Notably, the cortical bone free water parameters correlated with age, a finding statistically reinforced by Pearson correlation coefficients of 0.62 for concentration and 0.8 for T1free.

Implications

The findings underscore the feasibility of using STE-MRI with a dual-TR strategy as a clinical tool for quantifying cortical bone free water, offering an alternative to UTE-MRI techniques without requiring specialized hardware not typically present in clinical environments. This suggests that the new method could enhance the accessibility of cortical bone water assessments, thereby improving the ability to monitor age-related changes in bone quality and porosity, which are important for understanding and diagnosing bone-related conditions such as osteoporosis.

Future Directions

The results suggest avenues for further investigation, particularly in improving T1 quantification strategies and addressing potential methodological limitations like fat contamination and motion artifacts. The protocol's ease of integration into standard clinical practice opens potential for larger-scale studies to confirm its efficacy as a diagnostic tool.

Conclusion

Overall, this research provides an important step toward clinical adoption of MRI-based free water quantification for cortical bone, providing a reliable and accessible alternative to existing methods. The correlation of free water metrics with age further supports the potential for these measurements as surrogate markers for cortical bone porosity and age-related bone quality assessment.