Abstract： Objective To assess the value of combination of susceptibility weighted imaging (SWI)and dynamic susceptibility-weighted contrast-enhanced (DSC) perfusion-weighted magnetic resonance imaging in astrocytoma grading.Methods SWI and DSC scans were performed in 82 patients with pathologically confirmed astrocytoma.The patient group consisted of grade Ⅱ (15),grade Ⅲ (10),and grade Ⅳ (57).The intratumoral susceptibility signal intensity (ITSS) and relative cerebral blood volume (rCBV) max were used to determine the grade of astrocytomas by Kruskal Wallis test,Welch test,Spearman correlation coefficients,Pearson correlation coefficients,and receiver operating characteristic curve (ROC)statistic methods.Results There were no ITSS in 14 cases of low-grade astrocytomas,the degree of ITSS were grade 1 to 3 in anaplastic astrocytomas,the degree of ITSS were grade 3 in all of the glioblastomas,the degree of ITSS were significant difference in all grades (H =71.96,P ＜ 0.01).rCBV max in grade Ⅱ,grade Ⅲ and grade Ⅳ astrocytomas were 1.26 ± 0.42,3.59 ± 2.09 and 8.34 ± 1.16 respectively,rCBV max were significant difference in all grades (F' =681.72,P ＜ 0.01).ITSS showed significant correlation with rCBV max (r =0.72,P ＜0.01) and tumor grades (r =0.89,P ＜0.01),and rCBV and tumor grades showed significant correlation (r =0.78,P ＜ 0.01).Area under the ROC curve application SWI,DSC,SWI and DSC in differentiation of the grade Ⅱ and grade Ⅲ astrocytomas were 0.99,0.93,1.00,differentiate grade Ⅲ from grade Ⅳ were 0.70,0.94,0.94,and differentiate high-grade from low-grade astrocytomas were 1.00,0.99,1.00.Conclusions ITSS is helpful to determine the grade of astrocytomas.The use of SWI in combination with DSC may improve the diagnostic accuracy of astrocytoma grading.