摘要Background The degree of pathological microvascular proliferation is an important element in evaluation of the astrocytoma grade.This study was aimed to quantitatively assess the microvascular permeability of brain astrocytoma with the volume transfer constant (Ktrans) and volume of extravascular extracellular space per unit volume of tissue (Ve) from dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and to evaluate the effectiveness of the Ktrans and Ve in the grading of astrocytoma.Methods The highest values of the Ktrans and Ve of 67 patients with astrocytoma (27 with grade Ⅱ,12 with grade Ⅲ,and 28 with grade Ⅳ) were obtained.The comparisons of the differences of the Ktrans and Ve between the different grades were conducted using the Mann-Whitney rank-sum tests.Spearman's rank correlation coefficients were determined between Ktrans values,Ve values and astrocytoma grades.Receiver operating characteristic (ROC) curve analyses were performed to determine the cut-off values for the Ktrans and Ve to distinguish between the different grades of astrocytoma.Results There were significant differences (P＜0.001) between the different grades in the Ktrans values and Ve values,except for grades Ⅲ and Ⅳ.The Ktrans values and Ve values were both correlated with astrocytoma grades (both P＜0.001).The ROC curve analyses showed that the cut-off values for the Ktrans and Ve provided the best combination of sensitivity and specificity in distinguishing between grade Ⅱ and grade Ⅲ or Ⅳ astrocytomas.Conclusions DCE-MRI can play an important role in assessing the microvascular permeability and the grading of brain astrocytoma.