Diffusion tensor imaging in assessment of structural brain networks in patients with anti-N-methyl-D-aspartate receptor encephalitis / 中华放射学杂志

ABSTRACT

Objective:To explore the alteration of structural network, cognitive scores in patients with anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis, as well as the relationship between cognitive impairment and changes of structural networks in patients with NMDAR encephalitis.Methods:This study was a retrospective study. A total of 39 patients with anti-NMDAR encephalitis were recruited as the autoimmune encephalitis group (AE group) from the First Affiliated Hospital of Chongqing Medical University between September 2012 to December 2019, and 32 healthy volunteers with normal results of routine head MR examinations and no history of central nervous system diseases were recruited as the health control group (HC group). There were 16 males and 23 females, aged from 13 to 66 (34±15) years, with duration of disease from 11 to 110 (31±20) days in AE group, and there were 16 males and 23 females, aged from 13 to 66 (34±15) years in HC group. All subjects underwent diffusion tensor imaging (DTI) scan and cognitive function evaluation. The brain structural networks of two groups were constructed by deterministic fiber tracking techniques, and the differences of global topological properties [clustering coefficient (C p), shortest path length (L p), local efficiency (E loc), global efficiency (E glob), normalized C p (γ), normalized L p (λ), small-worldness (σ)] and local topological properties between two groups were analyzed by the graph theory approch. The correlations between characteristics of brain structural networks and cognitive function scores were further analyzed. Results:There was no significant difference in age and gender distribution between the AE group and HC group ( P>0.05). The C p [0.005(0.004, 0.007)], γ (1.76±0.13), λ (0.51±0.03) and σ value (1.57±0.13) of AE group were decreased when compared with HC group [the values were 0.007(0.004,0.017), 2.13±0.63, 0.55±0.06 and 1.73±0.36 each] ( Z=-939.00, t=-3.58, t=-4.16, t=-2.58, P<0.05). Compared with HC group, nodal efficiencies in the left middle frontal gyrus (orbital part), left and right supplementary motor areas, left olfactory cortex, left gyrus rectus, bilateral insula, left postcentral gyrus, left paracentral lobule and right heschl gyrus were changed ( P<0.05). There were five identical hub regions which contains the left middle occipital gyrus, bilateral supplementary motor areas and precuneus in both groups. However, in the AE group, three hub regions of the left middle occipital gyrus and bilateral middle temporal gyrus were reduced, and the left precentral gyrus was increased as hub region. The nodal efficiencies of the left supplementary motor areas ( r=0.393, P=0.013), right supplementary motor areas ( r=0.384, P=0.016) and left paracentral lobule ( r=0.356, P=0.026) were positively correlated with the montreal cognitive assessment scores. Conclusion:The white matter is extensively impaired in anti-NMDAR encephalitis patients and the changes of topological properties in several brain regions are correlated with cognitive decline.