Angioarchitecture Determines Obliteration Rate After Radiosurgery in Brain Arteriovenous Malformations

BACKGROUND: Radiosurgery as a potential treatment modality for brain arteriovenous malformations (AVM) has 60% to 90% obliteration rates. OBJECTIVE: To test whether AVM angioarchitecture determines obliteration rate after radiosurgery. METHODS: This study was a retrospective analysis of 139 patients with AVM who underwent radiosurgery. Multiple angioarchitectural characteristics were reviewed on conventional angiogram on the day of radiosurgery: enlargement of feeding arteries, flow-related or intranidal aneurysms, perinidal angiogenesis, arteriovenous transit time, nidus type, venous ectasia, focal pouches, venous rerouting, and presence of a pseudophlebitic pattern. The radiation plan was reviewed for nidus volume and eloquence of AVM location. A chart review was performed to determine clinical presentation and previous treatment. Outcome was dichotomized into complete/incomplete obliteration, and various statistics were performed, examining whether outcome status was associated with the investigated factors. RESULTS: Marginal dose ranged from 15 to 25 Gy (mean, 18.8 Gy), with lower doses prescribed in eloquent locations. Sizes of AVMs ranged from 0.08 to 21cm(3) (mean, 3.78 +/- 4.19 cm(3)). Complete AVM obliteration was achieved in 92 patients (66%) and was related to these independent factors: noneloquent location (odds ratio [OR], 3.20), size (OR, 0.88), low flow (OR, 3.47), no or mild arterial enlargement (OR, 3.32), and absence of perinidal angiogenesis (OR, 2.61). Concerning the 3 last angioarchitectural characteristics, if no or only a single factor was present in an individual patient (n = 92 patients), obliteration was observed in 74 (80%); if 2 or 3 factors were present (n = 47), obliteration was observed in 18 patients (38%; OR, 6.62). CONCLUSION: Angioarchitectural factors that indicate high flow are associated with a lower rate of AVM obliteration after radiosurgery.