Abstract: Abstract:Objective  To clarify the relationship between MRI quantitative parameters and astrocytoma related  indexes by analyzing the correlation between MRI quantitative parameters and the expression level of hypoxia inducible factor-1α（HIF-1α） in cerebral astrocytoma.Methods  A total of 33 cases of astrocytoma proved by operation and pathology were collected.The MRI quantitative parameters,such as edema index(EI),relative signal intensity on Gd-enhanced T1WI(RSIGd) and enhancement percentage(EP) were measured.The expression of HIF-1α in tumor tissues was detected with immunohistochemical method.Results The values of RSIGd and EP of low grade astrocytoma(WHO grade Ⅰ-Ⅱ) were significantly lower than those of  high grade astrocytoma (WHO grade Ⅲ-Ⅳ) (P<0.01).The EI value of low grade astrocytoma was lower than that of high grade astrocytoma(P<0.01).There was no expression of HIF-1α in normal brain tissue.But HIF-1α expressed in astrocytoma with different grades.The expression level of  HIF-1α  in low grade astrocytoma was lower than that in high grade astrocytoma(P<0.001).The expression level of  HIF-1α  was positively correlated with the value of RSIGd( r=0.431,P<0.05).The expression level of  HIF-1α  was significantly positively correlated with the value of EP (r=0.651,P<0.001).There was no obviously significant correlation between the level of  HIF-1α  and the value of EI (r=0.317,P>0.05).Conclusion  RSIGd and EP are very helpful to evaluate the pathological grades and the permeability of new vessels of cerebral astrocytoma.High grade cerebral astrocytomas are often accompanied by peritumoral edema but it can’t be explained by only one theory.

Key words: astrocytoma, hypoxia inducible factor-1&alpha, peritumoral edema, angiogenesis, magnetic resonance imaging