RESUMO
Objective To compare the difference of MRI characteristics of pilomyxoid astrocytomas (PMA)and pilocytic astrocy-tomas (PA)in hypothalamus/optic chiasma region.Methods The MR images and clinical materials of 20 PMAs and 20 PAs proved by pathology were reviewed retrospectively.Imaging characteristics and clinical materials were analyzed,including age,gender, size,the signal characteristics of the tumor,growth,enhancement pattern,hydrocephalus and leptomeningeal dissemination.Results There were statistically significant differences in streaky low signal intensity among the high intensity of T2 WI and leptomeningeal dissemination between PMA and PA (P <0.05).However,no statistically significant differences were found in the other character-istics and clinical materials between the two types of tumors.Conclusion PMA and PA in hypothalamus/optic chiasma region are difficult to make differential diagnosis.The streaky low signal intensity among the high intensity of T2 WI and more frequent lepto-meningeal dissemination are helpful differential features of PMA as compared to PA.