LGI1 and viral encephalitis: As shown in Figure 4 and summarized in Table 4, significantly increased PET signals were observed in the bilateral medial temporal lobe, the bilateral basal ganglia, the left precuneus, the left medial part of the superior frontal gyrus, the right postcentral gyrus, and the left calcarine fissure and surrounding cortex, indicating that the patients with anti-LGI1 encephalitis presented hypermetabolism in these brain regions.