Synthetic MRI for Detecting Abnormal Signals in the Optic Nerves

Objectives: Synthetic magnetic resonance imaging (MRI) is a quantitative imaging technique that has shown promise in brain imaging but has not yet been evaluated for assessing the optic nerves. Our study aimed to investigate its diagnostic performance in this context. Materials and Methods: We retrospectively evaluated synthetic MRI’s performance in detecting optic nerve hypersignals in 65 patients who underwent synthetic MRI covering the optic nerves from March 2023 to February 2025 in a single tertiary center. Diagnostic performance for optic nerve hypersignals was assessed using conventional T2 and/or FLAIR-weighted images with fat saturation as the reference standard. Quantitative T2 and proton density (PD) values were compared between optic nerves exhibiting hypersignals on synthetic MRI and those without any hypersignals. The detection rate of optic nerve hypersignals in patients with a diagnosis of acute optic neuritis was evaluated using synthetic MRI, both overall and for each individual synthetic contrast. For the qualitative analysis, sensitivity, specificity, and accuracy were each calculated with a 95% CI using the exact binomial (Clopper-Pearson) method. Quantitative differences in T2 and PD values were assessed using the Cohen d to evaluate effect size, and statistical significance was determined by the Wilcoxon rank-sum test. Results: Synthetic MRI showed good overall diagnostic performance for optic nerve hypersignals, with sensitivity, specificity, and accuracy of 71.4% [0.513-0.868], 97.1% [0.916-0.994], and 91.5% [0.854-0.957], respectively. Quantitative analysis revealed significantly higher median T2 (66.29 vs. 72.4 ms) and proton density (72.22 vs. 86.51) values in optic nerves exhibiting hypersignals compared with those without ( P <0.001 for both). For acute optic neuritis specifically, 6 out of 7 (85.7%) were correctly identified in synthetic MRI. Confidence scores did not significantly differ between patients with optic nerve hypersignals and those without. Conclusions: Synthetic MRI showed promising results in detecting abnormal signals in the optic nerves, suggesting its potential role in their clinical evaluation.