title: Detection of residual brain arteriovenous malformations after radiosurgery: diagnostic accuracy of contrast-enhanced four-dimensional MR angiography at 3.0 T.
abstract: OBJECTIVE
  To evaluate the diagnostic accuracy of four-dimensional MR angiography (4D-MRA) at 3.0 T for detecting residual arteriovenous malformations (AVMs) after Gamma Knife (Elekta Instrument AB, Stockholm, Sweden) radiosurgery (GKRS).
  
  
  METHODS
  We assessed 36 angiographically confirmed AVMs in 36 patients who had been treated with GKRS. 4D-MRA was performed after GKRS and the time intervals were 39.4 ± 26.0 months [mean ± standard deviation (SD)]. 4D-MRA was obtained at 3.0 T after contrast injection, with a measured voxel size of 1 × 1 × 1 mm and a temporal resolution of 1.1 s (13 patients) or a voxel size of 1 × 1 × 2 mm and a temporal resolution of 0.98 s (23 patients). X-ray angiography was performed as the standard reference within 53 ± 47 days (mean ± SD) after MRA. To determine a residual AVM, the 4D-MRA results were independently reviewed by two readers blinded to the X-ray angiography results. We evaluated diagnostic sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy of 4D-MRA for detection of a residual AVM.
  
  
  RESULTS
  A residual AVM was identified in 13 patients (13/36, 36%) on X-ray angiography. According to Readers 1 and 2, 4D-MRA had a sensitivity of 79.6% and 64.3%, a specificity of 90.9% and 100%, a PPV of 84.6% and 100% and an NPV of 90% and 81.5%, respectively, and a diagnostic accuracy of 86.1% for Readers 1 and 2, for detecting residual AVMs after GKRS.
  
  
  CONCLUSIONS
  The diagnostic accuracy of 4D-MRA at 3.0 T seems high, but there is still the possibility of further improving the spatiotemporal resolution of this technique.
authors.affiliation: Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Republic of Korea.
authors.forename: H K
authors.initials: HK
authors.lastname: Lim
authors.forename: C G
authors.initials: CG
authors.lastname: Choi
authors.forename: S M
authors.initials: SM
authors.lastname: Kim
authors.forename: J L
authors.initials: JL
authors.lastname: Kim
authors.forename: D H
authors.initials: DH
authors.lastname: Lee
authors.forename: S J
authors.initials: SJ
authors.lastname: Kim
authors.forename: D C
authors.initials: DC
authors.lastname: Suh
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D003287:Contrast Media; D005260:Female; D006801:Humans; D002538:Intracranial Arteriovenous Malformations / Q000175:diagnosis* / Q000601:surgery; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011184:Postoperative Period; D016634:Radiosurgery / Q000379:methods*; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D055815:Young Adult
chemical_list: D003287:Contrast Media