Hyperintensity on T2 MRI and size as predictors of obliteration in radiosurgically treated arteriovenous malformations

The aim of this study was to determine which factors were statistically related to radiological and clinical outcomes following radiosurgical treatment of arteriovenous malformations (AVMs). The data of 59 patients receiving radiosurgical treatment at our department were retrospectivelly reviewed. Different clinical and biological data, including Spetzler-Martin grade, the presentation of symptoms, radiation dose, number of isocenters and both radiological and clinical outcome, were subjected to multivariate analysis. AVM obliteration was achieved in 77% of patients, the majority of them occurring between 3-5 years after treatment. Ten patients (17%) showed either acute or delayed complications. Only one patient died due tor hemorrhage during the follow-up after radiosurgery. A multivariate analysis showed that, hyperintensity on T2 MRI and a nidus smaller than 3 cm were the only factors statistically related to oclusion of the AVM (p=0.03 and p=0.05, respectively). The nidus size and the development of hyperintensity on T2 MRI after the treatment were the strongest predictive factors of obliteration in our series of AVMs radiosurgically treated. Moreover, given that many AVMs showed complete obliteration between 3-5 years after treatment, we recommend to wait untill 5 years after treatment before considering a new terapeuthic approach in patients showing small residual nidus at control imaging.