Altered Microstructure of Cerebral Gray Matter in Neuromyelitis Optica Spectrum Disorder-Optic Neuritis: A DKI Study.

Hanjuan Zhang,Xiaoxia Qu,Qing Li,Junfang Xian,Lei Liu,Qian Wang,Bingbing Yang

doi:10.3389/fnins.2021.738913

Hanjuan Zhang, Xiaoxia Qu + Show 5 more

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https://doi.org/10.3389/fnins.2021.738913

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Abstract

The purpose of this study was to analyze microstructural alterations in cerebral gray matter using non-Gaussian diffusion kurtosis imaging (DKI) in neuromyelitis optica spectrum disorder (NMOSD) patients with optic neuritis (NMOSD-ON). DKI was performed in 14 NMOSD-ON patients and 22 normal controls (NCs). DKI-derived metrics, including mean kurtosis (MK), radial kurtosis (RK), axial kurtosis (AK), fractional anisotropy (FA), and mean diffusivity (MD), were voxel-wisely compared by two-sample t-tests with gaussian random field (GRF) correction between the two groups. The correlations between altered DKI metrics and clinical features were analyzed. Compared with NCs, NMOSD-ON patients showed significantly decreased MK and RK both in the left inferior temporal gyrus (ITG), and decreased AK in the bilateral calcarine (CAL). While increased MD in the left fusiform gyrus (FFG), right CAL, and right hippocampus (HIP)/parahippocampal gyrus (PHG) were found. Furthermore, correlation analysis showed that mean deviation was negatively correlated with AK values of bilateral CAL and positively correlated with MD values of right CAL (q < 0.05, false discovery rate (FDR) corrected). For NMOSD-ON patients, microstructural abnormalities in the occipital visual cortex are correlated with clinical disability. These findings may provide complementary information to understand the neuropathological mechanisms underlying the impairments of cerebral gray matter in NMOSD-ON.

Highlights

Neuromyelitis optica spectrum disorder (NMOSD) is an inflammatory demyelinating disease mediated by inflammation against the aquaporin-4 (AQP4) water channel on astrocytes predominantly attacked optic nerves and spinal cord
Correlation analysis showed that the mean deviation was negatively correlated with axial kurtosis (AK) values of bilateral CAL and positively correlated with mean diffusivity (MD) values of right CAL, showing the clinical implications of these findings in neuromyelitis optica spectrum disorder (NMOSD)-optic neuritis (ON)
Significantly decreased kurtosis metrics (MK, radial kurtosis (RK), and AK) and increased MD were detected in the visual cortices of NMOSD-ON, including bilateral CAL, left inferior temporal gyrus (ITG), and left fusiform gyrus (FFG)

Summary

Introduction

Neuromyelitis optica spectrum disorder (NMOSD) is an inflammatory demyelinating disease mediated by inflammation against the aquaporin-4 (AQP4) water channel on astrocytes predominantly attacked optic nerves and spinal cord. Most neuroimaging studies of NMOSD have reported structural damage predominantly restricted to white matter, especially for optic radiation which is characterized by decreased FA and increased MD using diffusion tensor imaging (DTI; Yu et al, 2008; Jeantroux et al, 2012; Liu et al, 2012; Rueda et al, 2012; Zhao et al, 2012). Increasing studies have shown subtle morphological alteration in the visual cortex beyond the optic radiation, featured by reduced gray matter volume (Pichiecchio et al, 2012; Von Glehn et al, 2014; Liu et al, 2018) and cortical atrophy (Calabrese et al, 2012; Liu et al, 2014) in NMOSD patients. Anterograde trans-synaptic degeneration through the lateral geniculate nuclei has been considered as the leading mechanism to explain the reduced volume or thickness of the primary visual cortex in NMOSD patients with ON (Von Glehn et al, 2014; Manogaran et al, 2016; Tian et al, 2018), but the evidence for this mechanism remains inadequate

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