LGI1 and autoimmune encephalitis: PURPOSE: To explore whether detecting local astrogliosis using [18F]fluorodeprenyl-D2 ([18F]F-DED) positron-emission-tomography (PET) uncovers and monitors inflammatory lesions in patients with anti-leucine-rich glioma-inactivated 1 antibody (LGI1-ab) associated autoimmune encephalitis (AE).