Abstract： Objective To describe the MR features of Rasmussen encephalitis (RE).Methods The MRI of 10 pathologic confirmed patients (7 male,3 female,mean age 11 ± 4 years) with RE were retrospectively analyzed in this study.Routine axial,sagittal and coronal (perpendicular to the oblique long axis of the hippocampus) scans were obtained for T1WI,T2WI and fluid-attenuated inversion recovery (FLAIR) images. The location and degree of cerebral atrophy,gray matter signal changes,and the evolution of these findings were evaluated. Results Brain atrophy included the enlargement of lateral ventricle(8/10),temporal horn (9/10)and lateral fissure (9/10); widened sulci and small gyri in the isolateral hemisphere (7/10) ; atrophy in caudate and putamen nucleus (6/10).The cortical atrophy was extensive at late stage of the RE,and usually was hemispheric or involved more than two lobes.The signal changes included hyperintensity involving extensive cortical and/or subcortical regions (9/10). The follow-up MR study demonstrated the progression of brain atrophy and extensive signal changes.Conclusions RE usually presents in pediatric patients. The imaging findings included progressive unilateral brain atrophy,enlargement of lateral ventricle,lateral fissure and sulci,and small gyri with or without cortical T2 hyperintensity.Deep nucleus atrophy may be involved in RE.