Multimodal magnetic resonance imaging quantification of gray matter alterations in relapsing‐remitting multiple sclerosis and neuromyelitis optica spectrum disorder

Abstract

Herein, we combined neurite orientation dispersion and density imaging (NODDI) and synthetic magnetic resonance imaging (SyMRI) to evaluate the spatial distribution and extent of gray matter (GM) microstructural alterations in patients with relapsingremitting multiple sclerosis (RRMS) and neuromyelitis optica spectrum disorder (NMOSD). The NODDI (neurite density index [NDI], orientation dispersion index [ODI], and isotropic volume fraction [ISOVF]) and SyMRI (myelin volume fraction [MVF]) measures were compared between age-and sex-matched groups of 30 patients with RRMS (6 males and 24 females; mean age, 51.43 ± 8.02 years), 18 patients with anti-aquaporin-4 antibody-positive NMOSD (2 males and 16 females; mean age, 52.67 ± 16.07 years), and 19 healthy controls (6 males and 13 females; mean age, 51.47 ± 9.25 years) using GM-based spatial statistical analysis. Patients with RRMS showed reduced NDI and MVF and increased ODI and ISOVF, predominantly in the limbic and paralimbic regions, when compared with healthy controls, while only increases in ODI and ISOVF were observed when compared with NMOSD. Compared to NDI and MVF, the changes in ODI and ISOVF were observed more widely, including in the cerebellar cortex. These abnormalities were associated with disease progression and disability. In contrast, patients with NMOSD only showed reduced NDI mainly in the cerebellar, limbic, and paralimbic cortices when compared with healthy controls and patients with RRMS. Taken together, our study supports the notion that GM pathologies in RRMS are distinct from those of NMOSD. However, owing to the limitations of the study, the results should be cautiously interpreted.

Neurite Orientation Dispersion and Density Imaging in Multiple Sclerosis: A Systematic Review

“…In addition, similar to the findings of NAWM, two studies explored specific regions of the NAGM 23,27 . Decreased NDI was observed, although mapping in different areas.…”

“…Decreased NDI was observed, although mapping in different areas. Andica et al, reported GM alterations in the insula, limbic, and paralimbic regions, 23 while Collorone et al observed widespread alterations in the visual cortex, occipital, parietal, and temporal lobes 27 . ISOVF was assessed only in one study, reporting elevated values in extensive NAGM regions, including entorhinal, fusiform, and superior temporal regions, cerebellum cortex, hippocampus, insula, and parahippocampus areas 23 .…”

“…Participants were age‐matched in four studies, 24,28,37,39 sex‐matched in one study 36 . Meanwhile, 15 studies controlled for both age and gender 16,18,23,26,27,29–31,33–35,40–43 …”

“…Andica et al, reported GM alterations in the insula, limbic, and paralimbic regions, 23 while Collorone et al observed widespread alterations in the visual cortex, occipital, parietal, and temporal lobes 27 . ISOVF was assessed only in one study, reporting elevated values in extensive NAGM regions, including entorhinal, fusiform, and superior temporal regions, cerebellum cortex, hippocampus, insula, and parahippocampus areas 23 . In addition to these two studies, in an independent study, Preziosa et al reported that ODI thalamus of MS patients was similar to HC, while NDI was reduced 36 .…”

“…In this review, we also tackled the associations between MS clinical outcomes and NODDI measures. We identified several studies reporting this analysis 18,23,26,27,29,32,35–37,41 . The EDSS score was the most common measure investigated.…”