Relationship between MRI characteristics and outcome after gamma knife radiosurgery for astrocytoma

The objective of the present study is to explore the relationship between MRI characteristics and outcome after gamma knife radiosurgery for astrocytoma. According to the characteristics of the definition and contrast enhancement of the lesions in the MRI examination, subjects were divided into three groups. The effectiveness was defined as astrocytoma shrinkage. The relationship between MRI characteristics and outcome after gamma knife radiosurgery were assessed. Twenty of 43 patients showed effectiveness. Thirteen of 18 showed effectiveness in type I group, 5 of 15 in type II group, and 2 of 10 in type III group. No significant difference was found among three type s in the age, gender, Karnofsky Performance Status (KPS), lesion location, mean maximal diameter of lesion, radiotherapy and chemotherapy. The WHO grade I/II glioma was more frequently found in the type I or II group than in type III group (P = 0.000, for both), but significant difference in the number of WHO I/II grade glioma was absent between type I group and type II group. The therapeutic effectiveness in the type I group was superior to that in type II and III groups (P< 0.05 for both), but there was no significant difference between type I group and type II group. The mean survival time was 15.8, 12.9 and 11.9 months in the type I, type II and type III groups, respectively, and marked difference was noted between type I group and type III group (P=0.025). Conclusion: Some MRI characteristics are related to outcomes after gamma knife radiosurgery for astrocytoma.