Purpose
TSPO PET with radioligand 18F-DPA714 is an emerging molecular imaging technique that reflects cerebral microglial activation and has been recently used in central nervous system diseases. In this study, we aimed to investigate the microglial activation pattern of anti–leucine-rich glioma-inactivated 1 (LGI1) protein autoimmune encephalitis (AIE) and to evaluate its correlation with clinical phenotypes.
Methods
Twenty patients with anti-LGI1 encephalitis from the autoimmune encephalitis cohort in Huashan hospital and ten with other AIE and non-inflammatory diseases underwent TSPO PET imaging were included in the current study. TSPO PET abnormalities in anti-LGI1 AIE were detected on a voxel basis using statistic parametric mapping analysis. Multiple correspondence analysis and hierarchical clustering were conducted for discriminate subgroups in anti-LGI1 AIE. Standardized uptake value ratios normalized to the cerebellum (SUVRc) were calculated for semiquantitative analysis of TSPO PET features between different LGI1-AIE subgroups.
Results
Increased distribution of 18F-DPA714 was identified in the bilateral hippocampus, caudate nucleus and frontal cortex in anti-LGI1 patients. Two subgroups of anti-LGI1 patients were distinguished based on the top seven common symptoms. Patients in cluster 1 had a high frequency of facio-brachial dystonic seizures than those in cluster 2 (p = 0.004), whereas patients in cluster 2 had a higher frequency of general tonic clonic seizures than those in cluster 1 (p < 0.001). Supplementary motor area and superior frontal gyrus showed higher 18F-DPA714 distribution in cluster 2 patients compared with those in cluster 1 (p = 0.024; p = 0.04, respectively).
Conclusions
Anti-LGI1 AIE has a distinctive molecular imaging pattern presented by TSPO PET scan. Different characteristics in LGI1-AIE subgroups indicate underlying mechanisms of microglia in pathogenesis and clinical phenotypes. Further studies are required for verifying its value in clinical application.