Abstract: Objective:To analyze the CT and MRI features of liposarcoma of the extremities and trunk for improving the diagnosis of the disease.Methods:The CT and MRI findings of 12 cases of primary liposarcoma confirmed by operation and pathology were analyzed retrospectively.Seven cases were examined by CT,11 cases by MRI,and 6 cases by both CT and MRI.Results:Among the 12 cases,6 were well differentiated liposarcoma,2 sclerosing liposarcoma,3 myxoid iposarcoma,2 pleomorphic and 1 was dedifferentiated liposarcoma.Seven cases were irregularly margined and five cases regularly margined.The mean diameter of the lesions ranged from 6.1 to 19.9 cm.Well differentiated liposarcom contained a large amount of mature fat.CT and MRI showed fat tissue which was well defined,and homogeneous in density and signal intensity(SI).Myxoid liposarcoma consisted mainly of myxoid matrix,containing a few well differentiated proliferating lipoblasts;CT and MRI demonstrated no or little fat with irregular density and mildly inhomogeneous SI.Pleomorphic liposarcoma had no characteristic of fat tissue,and the adjacent structures were infiltrated and edematous with apparently inhomogeneous density and SI.Dedifferentiated liposarcoma had a pretty large volume with apparently inhomogeneous density and SI.The enhancement was highly intensified.Conclusions:CT and MRI can reflect the histological features of liposarcoma of the extremities and trunk,and demonstrate the exact boundaries of tumors,the actual area and surrounding tissues.The degree of histology differentiation and malignancy can be evaluated on the basis of CT and MRI findings of liposarcoma.