title: Toward normal perfusion after radiosurgery: perfusion MR Imaging with independent component analysis of brain arteriovenous malformations.
abstract: OBJECTIVE
  Brain perfusion is disturbed by cerebral arteriovenous malformations (AVMs). Our study was conducted to determine the radiosurgical effects on this disturbed perfusion.
  
  
  METHODS
  MR perfusion imaging with independent component analysis was performed in five healthy subjects and 19 patients with AVM before and after radiosurgery (every 6 months up to 2 years). Perfusion map relative cerebral blood volume (rCBV), cerebral blood flow (rCBF), and mean transient time (rMTT) were assessed. Regions of interest (ROIs) on AVM target sections were defined as follows: N, AVM nidus; H, the rest of the ipsilateral hemisphere; P, immediately posterior to the nidus; A, immediately anterior to the nidus; Ar, anterior remote; Pr, posterior remote. Similar ROIs in the contralateral hemisphere (N1, H1, P1, A1, Pr1, and Ar1) served as internal references. Perfusion ratios of ROI-ROI1 were defined. Nonparameteric Mann-Whitney U tests and generalized linear models were used for statistical analysis.
  
  
  RESULTS
  Before radiosurgery, patients' H/H1 rCBV and rCBF ratios were significantly higher than those of healthy subjects (P < .005), indicating AVM steal. Three types of perilesional perfusion disturbance were observed. From the first postradiosurgical follow-up at 6 months, N/N1 rCBV and rCBF ratios gradually decreased to 1.0 (both P < .001), whereas rMTT ratios gradually increased to 1.0 (P < .015); H/H1, A/A1, and P/P1 rCBV and rCBF ratios decreased after radiosurgery (P < .005), indicating reversal of steal toward normal perfusion.
  
  
  CONCLUSIONS
  Initial high transnidal flow and perinidal perfusion disturbances were demonstrated. They gradually changed toward normal perfusion after radiosurgery. This explains, in part, the pathophysiologic factors of AVM and therapeutic effects.
authors.affiliation: Department of Radiology, Taipei Veterans General Hospital, No, 201, Section II, Shih-Pai Road, 112 Taipei, Taiwan, ROC.
authors.forename: Wan-Yuo
authors.initials: WY
authors.lastname: Guo
authors.forename: Yu-Te
authors.initials: YT
authors.lastname: Wu
authors.forename: Hsiu-Mei
authors.initials: HM
authors.lastname: Wu
authors.forename: Wen-Yuh
authors.initials: WY
authors.lastname: Chung
authors.forename: Yi-Hsuan
authors.initials: YH
authors.lastname: Kao
authors.forename: Tzu-Chen
authors.initials: TC
authors.lastname: Yeh
authors.forename: Cheng-Ying
authors.initials: CY
authors.lastname: Shiau
authors.forename: D Hung-Chi
authors.initials: DH
authors.lastname: Pan
authors.forename: Yue-Cune
authors.initials: YC
authors.lastname: Chang
authors.forename: Jen-Chuen
authors.initials: JC
authors.lastname: Hsieh
mesh_terms: D000328:Adult; D015901:Angiography, Digital Subtraction; D001810:Blood Volume; D002339:Carotid Arteries / Q000000981:diagnostic imaging; D016022:Case-Control Studies; D002533:Cerebral Angiography; D002560:Cerebrovascular Circulation; D005260:Female; D006801:Humans; D002538:Intracranial Arteriovenous Malformations / Q000175:diagnosis / Q000503:physiopathology* / Q000601:surgery*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011184:Postoperative Period; D016896:Treatment Outcome