Objective:To investigate microstructural alterations in the optic chiasm and optic radiations of multiple sclerosis (MS) and neuromyelitis optica spectrum disorders (NMOSD) based on diffusion kurtosis imaging (DKI).Methods:This study was a cross-sectional study. Retrospective analyses were conducted on the clinical and imaging data of 63 patients with relapsing-remitting MS (RRMS) and 62 patients with NMOSD diagnosed at First Affiliated Hospital of Chongqing Medical University from January 2019 to December 2023. According to the occurrence of optic neuritis (ON), they were categorized into ON-positive MS (ON+MS) group (40 cases), ON-negative MS (ON-MS) group (23 cases), ON-positive NMOSD (ON+NMOSD) group (40 cases) and ON-negative NMOSD (ON-NMOSD) group (22 cases). In addition, 40 healthy controls were enrolled during the same period. DKI data of all subjects were collected, and DKI post-processing was performed to obtain fractional anisotropy (FA), mean kurtosis (MK), axial kurtosis (AK), and radial kurtosis (RK) values of the optic chiasm and bilateral optic radiations. The scores of the mini-mental state examination (MMSE), montreal cognitive assessment (MoCA), and expanded disability status scale (EDSS) were obtained. The Kruskal-Wallis test was used to analyze the differences in DKI parameters of the optic chiasm and bilateral optic radiation among the 5 groups, and the Holm-Bonferroni method was employed for multiple comparison correction in pairwise comparisons.Results:There were statistically significant overall differences in the DKI parameters of the optic chiasm and bilateral optic radiations among healthy control group, ON+MS group, ON-MS group, ON+NMOSD group, and ON-NMOSD group (all P0.05). The FA value of the optic chiasm in ON+NMOSD group was significantly lower than that of healthy control group and ON-MS group, as well as ON-NMOSD group ( P0.05). The FA value of the left optic radiation in ON+NMOSD group was lower than that in healthy control group and the ON-MS group. The RK value of the optic chiasm in ON+MS group was lower than that in the healthy control group and ON-NMOSD group ( P0.05). The MK and RK values of the left optic radiation in ON-MS group were significantly lower than those in the ON+NMOSD group and ON-NMOSD group ( P0.05). Conclusions:NMOSD and RRMS patients demonstrate varying degrees of microstructural damage in the optic chiasm and optic radiations. Differences of DKI parameters suggest different pathological mechanisms of visual pathway damage between NMOSD and MS, which may be helpful for early detection of occult visual pathway lesions.

Objective:To investigate microstructural alterations in the optic chiasm and optic radiations of multiple sclerosis (MS) and neuromyelitis optica spectrum disorders (NMOSD) based on diffusion kurtosis imaging (DKI).Methods:This study was a cross-sectional study. Retrospective analyses were conducted on the clinical and imaging data of 63 patients with relapsing-remitting MS (RRMS) and 62 patients with NMOSD diagnosed at First Affiliated Hospital of Chongqing Medical University from January 2019 to December 2023. According to the occurrence of optic neuritis (ON), they were categorized into ON-positive MS (ON+MS) group (40 cases), ON-negative MS (ON-MS) group (23 cases), ON-positive NMOSD (ON+NMOSD) group (40 cases) and ON-negative NMOSD (ON-NMOSD) group (22 cases). In addition, 40 healthy controls were enrolled during the same period. DKI data of all subjects were collected, and DKI post-processing was performed to obtain fractional anisotropy (FA), mean kurtosis (MK), axial kurtosis (AK), and radial kurtosis (RK) values of the optic chiasm and bilateral optic radiations. The scores of the mini-mental state examination (MMSE), montreal cognitive assessment (MoCA), and expanded disability status scale (EDSS) were obtained. The Kruskal-Wallis test was used to analyze the differences in DKI parameters of the optic chiasm and bilateral optic radiation among the 5 groups, and the Holm-Bonferroni method was employed for multiple comparison correction in pairwise comparisons.Results:There were statistically significant overall differences in the DKI parameters of the optic chiasm and bilateral optic radiations among healthy control group, ON+MS group, ON-MS group, ON+NMOSD group, and ON-NMOSD group (all P0.05). The FA value of the optic chiasm in ON+NMOSD group was significantly lower than that of healthy control group and ON-MS group, as well as ON-NMOSD group ( P0.05). The FA value of the left optic radiation in ON+NMOSD group was lower than that in healthy control group and the ON-MS group. The RK value of the optic chiasm in ON+MS group was lower than that in the healthy control group and ON-NMOSD group ( P0.05). The MK and RK values of the left optic radiation in ON-MS group were significantly lower than those in the ON+NMOSD group and ON-NMOSD group ( P0.05). Conclusions:NMOSD and RRMS patients demonstrate varying degrees of microstructural damage in the optic chiasm and optic radiations. Differences of DKI parameters suggest different pathological mechanisms of visual pathway damage between NMOSD and MS, which may be helpful for early detection of occult visual pathway lesions.