Assessing optic nerve integrity in optic neuritis with conventional magnetic resonance imaging.

BACKGROUND AND PURPOSE: The aim of this study was to investigate the integrity of the optic nerve using the ratio between T1WI and T2WI (T1/T2) MRI signal intensities, and to assess whether inter-eye differences could indicate the presence of lesions in the optic nerve.

MATERIAL AND

METHODS

The cohort included eighteen healthy controls and forty-nine individuals with multiple sclerosis; from those, thirty-two had a previous episode of optic neuritis. A method was trained to generate automatic segmentations of the optic nerve. Provided masks were then applied to the T1/T2 map and the mean profile was extracted. Inter-eye asymmetry was calculated from the area under the profiles. The presence of optic nerve lesions was confirmed using double inversion recovery MRI. Group differences were evaluated with non-parametric statistical tests, and the ability of inter-eye asymmetry to identify lesions was assessed using logistic regression.

RESULTS

Automated masks showed a moderate agreement with the reference segmentations (mean Dice coefficient ± SD = 0.53 ± 0.12). Eyes with a visible lesion on MRI showed a significantly lower T1/T2 (mean ± SD = 0.61 ± 0.09) compared to other groups (multiple sclerosis without optic neuritis 0.74 ± 0.06, p<0.001; and healthy subjects 0.77 ± 0.09, p<0.001). Inter-eye asymmetry demonstrated a good discriminative performance, with an area under the curve of 0.83, a sensitivity of 0.74, and a specificity of 0.82.

CONCLUSION

The findings indicate that conventional MRI can provide clinically meaningful information regarding optic nerve integrity and support the development of automated tools for detecting optic nerve lesions.