Can the probability for obliteration after radiosurgery for arteriovenous malformations be accurately predicted?

Purpose: To investigate how accurate different models predict the probability for obliteration following radiosurgery for an arteriovenous malformation (AVM), Methods and Materials: The probability for obliteration was calculated for all 838 AVMs with a known treatment outcome and treated at the Karolinska Hospital with Gamma Knife surgery 1970-1993, Four different models were used for the calculation, resulting in four different values of the probability for obliteration. The calculated prediction values were added for each model, and the total number of predicted obliteration compared to that observed in the whole patient material as well as in different subgroups. Results: Three of the four models predicted the total number of obliterations accurately. In two of those three models, the accuracy of the prediction was dependent on AVM volume and treatment dose. In one model only, the prediction was accurate and independent of all investigated parameters. Conclusions: The probability for obliteration was accurately predicted by one of the models analyzed. In this model, the probability for obliteration was related to the dose to the AVM periphery only. The AVM volume had no independent impact on the probability for obliteration. There was a trend that AVMs with a central location had a better obliteration rate than predicted. (C) 1999 Elsevier Science Inc.