title: Application of susceptibility weighted imaging (SWI) for evaluation of draining veins of arteriovenous malformation: utility of magnitude images.
abstract: BACKGROUND
  The current study evaluated the signal characteristics of susceptibility weighted imaging (SWI) of arteriovenous malformation (AVM), especially for draining veins. For this purpose, we identified the draining veins of the AVM on angiography and evaluated the signal on magnitude image for SWI (SWI-mag) and minimum intensity projection image (SWI-minIP).
  
  
  METHODS
  Subjects were 14 cases with angiographically proven AVM. SWI-mag, SWI-minIP, and time-of-flight (TOF) magnetic resonance angiography were acquired. For the draining veins of the AVM identified on angiography, we analyzed signal intensity on the images listed above, and classified it into hyperintensity (hyper), mixed intensity (mixed), hypointensity (hypo), and no visualization.
  
  
  RESULTS
  On the analysis of 27 angiographically proven draining veins, 19 draining veins were classified as hyper, 3 as mixed, 0 as hypo, and 6 as no visualization on SWI-mag. On TOF images, 21 draining veins were classified as hyper, 2 as mixed, 0 as hypo, and 4 as no visualization, while 6 draining veins did not show hyperintensity on TOF, and SWI-mag visualized 3 of these 6 veins as hyper.
  
  
  CONCLUSIONS
  SWI-mag depicted most draining veins of AVM as hyperintensity. We speculate that this is mainly due to the higher concentration of oxygenated hemoglobin (oxy-Hb) and inflow effect of the draining vein. SWI-mag seems to be useful in the analysis and follow-up for AVM as the signal on the image may reflect physiological status.
authors.affiliation: Department of Radiology, Nara Medical University, 840 Shijo-cho, Kashihara, Nara, Japan. michy@altgo.net
authors.forename: Toshiteru
authors.initials: T
authors.lastname: Miyasaka
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Taoka
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Nakagawa
authors.forename: Takeshi
authors.initials: T
authors.lastname: Wada
authors.forename: Katsutoshi
authors.initials: K
authors.lastname: Takayama
authors.forename: Kaoru
authors.initials: K
authors.lastname: Myochin
authors.forename: Masahiko
authors.initials: M
authors.lastname: Sakamoto
authors.forename: Tomoko
authors.initials: T
authors.lastname: Ochi
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Akashi
authors.forename: Kimihiko
authors.initials: K
authors.lastname: Kichikawa
mesh_terms: D000328:Adult; D000368:Aged; D001921:Brain / Q000098:blood supply*; D005260:Female; D006801:Humans; D002538:Intracranial Arteriovenous Malformations / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D059906:Neuroimaging / Q000379:methods*; D012189:Retrospective Studies; D014680:Veins; D055815:Young Adult