A DOSE-RESPONSE ANALYSIS OF ARTERIOVENOUS MALFORMATION OBLITERATION AFTER RADIOSURGERY

Purpose: Although radiosurgery is effective in obliterating the pathol ogic vessels of intracranial arteriovenous malformations (AVM), the re lationships of both dose and volume to obliteration have not been well defined. Methods and Materials: The results of radiosurgery in 197 AV M patients with 3-year angiographic follow-up were analyzed. Volume va ried from 0.06-18 cc (median: 4.1 cc), and minimum target dose (D-min) varied from 12.0-25.6 Gy (median: 20.0 Gy). Results: Follow-up angiog raphy revealed complete AVM obliteration in 142 out of 197 patients (7 2%), The targeted AVM nidus failed to obliterate in 20 patients (10%), but in-field obliteration was complete in the remaining 35 patients ( 18%) discovered to have residual untargeted AVM nidus, Multivariate lo gistic regression a analysis of in-field obliteration revealed a signi ficant independent correlation with D-min (p = 0.04), but not with vol ume or maximum dose. A sigmoid dose-response curve for in-field oblite ration was constructed that significantly differed from the dose-volum e-response relationships that would have been expected from overall ob literation data. Conclusions: The success rate for in-field obliterati on of AVM after radiosurgery depends on D-min but does not appear to c hange appreciably with volume or maximum dose, Success rates for compl ete obliteration additionally are limited by problems defining the com plete AVM nidus. Copyright (C) 1996 Elsevier Science Inc.