Diffusion tensor imaging parameters in the presence of optic neuritis in multiple sclerosis.

OBJECTIVE

This study examined how different diffusion tensor imaging (DTI) acquisition planes affect diffusion tensor indices in multiple sclerosis (MS) patients, stratified by optic neuritis (ON) history.

MATERIALS AND

METHODS

Thirty-seven relapsing-remitting MS patients were prospectively enrolled: 20 with a history of ON (MSwON) and 17 without (MSwoON). Each participant underwent DTI in both axial and coronal planes using a 1.5 Tesla MRI system. Optic nerve regions of interest were drawn independently for each plane, and 18 DTI-derived parameters were compared between groups using linear mixed-effects models with False Discovery Rate correction.

RESULTS

No significant group effect was detected for any DTI parameter (p > 0.05), suggesting that diffusion metrics were broadly comparable between MSwON and MSwoON patients. The group × acquisition plane interaction was also non-significant across all parameters. In contrast, acquisition plane exerted a significant main effect on ten parameters following FDR correction - among them Fractional Anisotropy, Apparent Diffusion Coefficient, Mean Diffusivity, and Radial Diffusivity - with axial acquisitions consistently yielding higher diffusivity and anisotropy values than coronal ones.

CONCLUSION

Optic nerve DTI parameters did not differ significantly between MSwON and MSwoON patients, a finding compatible with subclinical bilateral nerve involvement in both groups. The marked dependence of multiple DTI metrics on acquisition plane points to the non-negligible role of imaging geometry, EPI-related distortions, and partial volume contamination in small-structure DTI measurements.