Diffusion tensor imaging of the human thigh: consideration of DTI-based fiber tracking stop criteria

To consider the tract-based analysis of DTI parameters in human muscle by assessing different fiber tracking stop criteria settings on diffusion parameters.

30 healthy volunteers underwent a 3 T MRI. Diffusion-weighted images were acquired to perform DTI and fiber tracking analysis for six thigh muscles. Whole thigh muscles were evaluated by fiber tractography using different fiber tracking stop parameters [FA (0.01-0.15) to (0.4-0.99); angle 10°-30°, step size 0.75 mm, 1.5 mm, 3 mm]. Diffusion and tractography-derived parameters per stop criterion were compared using a repeated measure ANOVA including Bonferroni-corrected post hoc tests.

We found significant differences in all examined diffusion parameters between different stop criteria (main effect p < 0.001). We showed different influence of tracking parameters on diffusion parameters in examined muscles (main effect p ≤ 0.001).

Statistically significant differences in fiber tracking results using different stop criteria were shown. Fiber tracking stop criteria do have an important influence on study results and should be considered in the development of study protocols and comparison of studies. We recommend a FA minimum of 0.10 and a step size lower than voxel size, e.g., a half with a constant ratio between step size and angle of 10°/mm.