Abstract: ObjectiveTo investigate the MR imaging features and diagnostic points of anaplastic astrocytoma. MethodsMR studies of 12 patients with pathologically confirmed anaplastic astrocytomas（WHO Ⅲ grade） were reviewed retrospectively. ResultsThe tumors were mainly located in frontal lobe (50%), and 1 case presented multiple lesions. The tumors showed the performance of cystic-solid(83.33%). Compared with gray matter, solid part has a signal of iso-intensity in T1WI and slight hyper-intensity in T2WI and FLAIR, with an obviously irregular ring enhancement. The tumors were mainly located in the cortex and involved the white matter. Those tumors with large lesions exhibited necrosis or calcification inside them, heavily mass effect, peripheral edema, bad-demarcated border, and obviously oppressed surrounding tissue, offset the midline; while those tumors were rarely not overpassed to the contralateral hemisphere. The case of multiple lesions showed unspecific performance. ConclusionMRI can clearly detect the extent and feature of anaplastic astrocytoma and should be the first modality of choice in showing the tumor spectrum, which has a significant clinical value for the diagnosis of anaplastic astrocytoma and for the differential diagnosis.