title: Stereotactic radiosurgery for brain arteriovenous malformations: quantitative MR assessment of nidal response at 1 year and angiographic factors predicting early obliteration.
abstract: BACKGROUND
  We investigated the role of magnetic resonance angiography (MRA) in the early follow-up of patients after stereotactic radiosurgery (STRS) for cerebral arteriovenous malformations (AVMs) and determined the influence of individual morphological factors of AVMs in early response to treatment.
  
  
  METHODS
  A group of 40 patients (41 AVMs) consented to a dedicated 1.5-T MR protocol 12 months after receiving STRS for a brain AVM. In addition to standard spin echo sequences, 3-D contrast-enhanced sliding interleaved Ky MRA (CE-SLINKY) and dynamic time-resolved subtraction angiography (MR-DSA) were performed. Nidal volumes were calculated using CE-SLINKY data in patients with a persisting arteriovenous shunt. Planning angiographic data was investigated in all 40 patients. The following AVM factors were used in the statistical analysis to determine their role in nidus obliteration: (1) maximum linear dimension, (2) nidal volume, (3) AVM location (4) nidal morphology, (5) venous drainage, (6) "high-flow angiographic change", (7) prior embolization, and (8) dose reduction.
  
  
  RESULTS
  Complete nidal obliteration was found in 9 patients, 26 showed greater than 50% nidal reduction and 6 had less than 50%. Two AVM factors, venous drainage and AVM location, were found to significantly correlate with rate of obliteration.
  
  
  CONCLUSIONS
  We successfully demonstrated the use of MRA to quantitatively assess the response of AVMs to STRS. Two AVM factors, venous drainage and AVM location were found to correlate with rate of obliteration prior to the application of the Bonferroni correction, but if this more rigorous statistical test was applied then none of the factors was found to be significant.
authors.affiliation: Section of Academic Radiology, University of Sheffield, Royal Hallamshire Hospital, Glossop Road, Sheffield, S10 2JF, England, UK. s.nagaraja@shef.ac.uk
authors.forename: S
authors.initials: S
authors.lastname: Nagaraja
authors.forename: K J
authors.initials: KJ
authors.lastname: Lee
authors.forename: S C
authors.initials: SC
authors.lastname: Coley
authors.forename: D
authors.initials: D
authors.lastname: Capener
authors.forename: L
authors.initials: L
authors.lastname: Walton
authors.forename: A A
authors.initials: AA
authors.lastname: Kemeny
authors.forename: I D
authors.initials: ID
authors.lastname: Wilkinson
authors.forename: P D
authors.initials: PD
authors.lastname: Griffiths
mesh_terms: D000293:Adolescent; D000328:Adult; D002533:Cerebral Angiography; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D002538:Intracranial Arteriovenous Malformations / Q000175:diagnosis* / Q000601:surgery*; D018810:Magnetic Resonance Angiography; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D016634:Radiosurgery; D012189:Retrospective Studies; D013997:Time Factors; D016896:Treatment Outcome