[Linac-based stereotactic radiosurgery for arteriovenous malformations (AVMs) in brain: estimation for efficacy of...

The purpose of this study was to determine whether it is possible to predict the efficacy of therapeutic response to linac-based stereotactic radiosurgery for AVMs on the basis of the stagnation rate in the nidus, which was defined as follows: [(pooling time of contrast material in the nidus of AVM)/ (intracranial circulation time)] x 100. Cerebral angiograms of twenty-five AVMs were retrospectively evaluated, and the stagnation rates in the nidus were calculated before and one year after stereotactic radiosurgery. Reduction rate was also calculated by using angiography, and we statistically evaluated the relationship between the stagnation rates in the nidus and the reduction rates. The stagnation rates in the nidus prior to linac-based stereotactic radiosurgery were positively correlated with the reduction ratios of AVMs after stereotactic radiosurgery (r = 0.406, p = 0.0432). Our study suggested that a higher stagnation rate in the nidus of the AVM might be obliterated faster after linac-based stereotactic radiosurgery. Thus, calculation of the stagnation rate in the nidus before stereotactic radiosurgery is useful in predicting the efficacy of therapeutic response to linac-based stereotactic radiosurgery for AVMs.