Activated microglia by 18F-DPA714 PET in a case of anti-LGI1 autoimmune encephalitis.

We reported a female patient with severe memory loss and faciobrachial dystonic seizures. Anti-LGI1 antibodies were detected in both serum and cerebrospinal fluid. Brain MRI only showed subtle abnormality. She received immunotherapy but unfortunately underwent two relapses after the first attack, resulting in gradual memory decline. Intriguingly, we found higher distribution of 18F-DPA714 in her left medial temporal lobe by PET/CT scan. A novel non-invasive molecular imaging technology indicated potential microglial activation, which might be a promising biomarker for diagnosing and monitoring anti-LGI1 autoimmune encephalitis.