Objective:To explore the clinical and imaging features of leucine-rich glioma inactivated 1 antibody associated autoimmune encephalitis (LGI1-AE).Methods:Nine LGI1-AE patients had conformed diagnosis in Department of Neurology, First Affiliated Hospital, School of Medicine, Zhejiang University from January 2016 to December 2021 were enrolled. A retrospective analysis was performed on the clinical manifestations, MRI and PET-CT features, and clinical outcomes of these patients.Results:One patient had acute onset due to sudden disturbance of consciousness; 3 had subacute onset with a duration of 10-15 d, manifested as dizziness, memory loss, unconsciousness and limb convulsions; 5 had chronic onset with a duration of 6 months-2 years, manifested as amnesia, memory loss, dizziness, and headache in the early stage of the disease, including 2 accompanied by emotional stress and personality changes. Eight patients were followed up for an average of 8 months: 1 with acute onset had organic mental disorder (dementia state), 3 had recurrent seizures (1 with subacute onset and 2 with chronic onset), and the remaining 4 had symptom relief or disappearance. In these 9 patients, 8 patients, enjoying good prognosis, showed typical imaging findings: lesions were located at the limbic system, morphological swelling was accompanied by increased T2WI signal, and PET showed reduced or increased metabolism; 1 patient, enjoying poor prognosis, had atypical imaging finding: asymmetric hyperintensity in the basal ganglia, the clinical symptoms were more severe than the 8 patients having lesions at the limbic system, and rapid disease progress was noted.Conclusion:The prognosis of LGI1-AE patients with atypical imaging manifestations might be relatively poor.