title: Arteriovenous shunt visualization in arteriovenous malformations with arterial spin-labeling MR imaging.
abstract: OBJECTIVE
  A reliable quantitative technique for measuring arteriovenous (AV) shunt in vascular malformations is not currently available. Here, we evaluated the hypothesis that continuous arterial spin-labeled (CASL) perfusion MR imaging can be used to detect and measure AV shunt in patients with arteriovenous malformations (AVMs).
  
  
  METHODS
  CASL perfusion MR imaging was performed in 7 patients with AVMs. Semiquantitative AV shunt estimates were generated based on a thresholding strategy by using signal-intensity difference (DeltaM) images to avoid potential errors in cerebral blood flow (CBF) calculation related to abnormal transit times and nonphysiologic blood-tissue water exchange in and around the AVMs. The potential for measuring CBF in regions distant from and near the AVM was explored, as was the relationship of CBF changes related to the size of the shunt.
  
  
  RESULTS
  In all 7 cases, striking increased intensity was seen on CASL perfusion DeltaM maps in the nidus and venous structures draining the AVM. Shunt estimates ranged from 30% to 0.6%. Mean CBF measurements in structures near the AVMs were not significantly different from the contralateral measurements. However, CBF in adjacent ipsilateral white matter increased relative to the contralateral side as the percent shunt increased (P = .02). Cortical gray matter CBF Delta (contralateral-ipsilateral) values demonstrated the same effect, but the correlation was weak and not significant. Thalamic CBF decreased ipsilaterally with increasing percent AV shunt (P = .01), indicating a possible steal effect. Basal ganglia Delta values showed little change in CBF with the size of the AV shunt.
  
  
  CONCLUSIONS
  CASL perfusion MR imaging can demonstrate AV shunting, providing high lesion conspicuity and a novel means for evaluating AVM physiology.
authors.affiliation: Department of Radiology, University of Pennsylvania Medical Center, Philadelphia, PA 19104, USA. Ronald.Wolf@uphs.upenn.edu
authors.forename: R L
authors.initials: RL
authors.lastname: Wolf
authors.forename: J
authors.initials: J
authors.lastname: Wang
authors.forename: J A
authors.initials: JA
authors.lastname: Detre
authors.forename: E L
authors.initials: EL
authors.lastname: Zager
authors.forename: R W
authors.initials: RW
authors.lastname: Hurst
mesh_terms: D000328:Adult; D000368:Aged; D004621:Embolization, Therapeutic; D006801:Humans; D002538:Intracranial Arteriovenous Malformations / Q000175:diagnosis* / Q000628:therapy; D018810:Magnetic Resonance Angiography; D008875:Middle Aged; D013113:Spin Labels
chemical_list: D013113:Spin Labels