Paraspinal Muscle DTI Metrics Predict Muscle Strength

Area of Science:

• Musculoskeletal Imaging
• Biomedical Engineering
• Radiology

Background:

• Lower back pain is often associated with paraspinal muscle function.
• Identifying imaging biomarkers for paraspinal musculature is clinically significant.
• Diffusion tensor imaging (DTI) offers microstructural examination of muscle tissue and pathology.

Purpose of the Study:

• To investigate the associations between DTI parameters of lumbar paraspinal muscles and isometric strength measurements.
• To explore the relationship between DTI-derived microstructural properties and functional strength in healthy individuals.

Main Methods:

• Prospective study involving 21 healthy subjects (12 male, 9 female).
• 3T/ss-EPI DTI in 24 directions and water-fat separation imaging were utilized.
• Lumbar paraspinal muscles (erector spinae) were segmented to calculate cross-sectional area (CSA), proton density fat fraction (PDFF), and DTI parameters. Maximum isometric torque (flexion/extension) was measured, and the extension-to-flexion strength ratio (E/F) was calculated.

Main Results:

• Significant positive correlations were observed between the E/F strength ratio and DTI parameters: mean diffusivity (MD), radial diffusivity (RD), and eigenvalues (λ1, λ2, λ3).
• Multivariate regression analysis identified λ3 of the erector spinae muscle and gender as significant predictors of E/F (adjusted R² = 0.42, P = 0.003).

Conclusions:

• DTI can identify microstructural differences in back muscles related to function, which are not apparent with CSA and PDFF measurements.
• DTI shows potential for tracking subtle changes in back muscle tissue composition.
• This technique may provide novel imaging biomarkers for assessing paraspinal muscle health and function.