Purpose: The discrimination between neuromyelitis optica (NMO)- and multiple sclerosis (MS)-related acute optic neuritis (ON) after the first presentation is difficult in clinical practice. Through a comparison with diffusion-weighted imaging using readout-segmented echo-planar imaging (RESOLVE-DWI), our aim was to determine the feasibility of diffusional kurtosis imaging (DKI) for differential diagnosis.
Materials and methods: Orbital DKI and RESOLVE-DWI in a 3.0-T scanner were performed on 37 patients with acute ON (15 NMO-related and 22 MS-related). The mean kurtosis (MK), axial kurtosis (AK), radial kurtosis (RK), mean diffusivity (MD), and apparent diffusion coefficient (ADC) were calculated for quantitative analyses, and receiver operating characteristic curve analyses were also performed to determine their abilities to differentiate the 2 conditions.
Results: The intraclass correlation coefficients among observers were 0.842, 0.885, 0.828, 0.871, and 0.942 for MK, RK, AK, MD, and ADC, respectively, in the affected nerve group and 0.890, 0.840, 0.832, 0.934, and 0.941 in the unaffected nerve group. Regarding the comparisons of the DKI and RESOLVE-DWI parameters among the groups, the mean MK, RK, AK, MD, and ADC values were significantly lower in the affected groups (all, P < 0.001). Furthermore, the MK, RK, MD, and ADC values were significantly lower in the NMO-ON group than in the MS-ON group (P = 0.001, 0.002, 0.013, and <0.001, respectively), and no significant differences were found in the AK values (P = 0.064). In addition, establishing MK ≤ 0.843 as the diagnostic criterion for NMO-related acute ON provided the highest sensitivity (90.5%), whereas the highest specificity (91.3%) was obtained using RK ≤ 0.784 as the diagnostic criterion.
Conclusions: Diffusional kurtosis imaging is helpful for differentiating NMO-related acute ON from MS-related acute ON, and it can achieve more agreeable sensitivity and specificity than RESOLVE-DWI in differential diagnosis.