title: FLAIR vascular hyperintensities and dynamic 4D angiograms for the estimation of collateral blood flow in posterior circulation occlusion.
abstract: BACKGROUND
  The objectives of this paper are to assess collateral blood flow in posterior circulation occlusion by MRI-based approaches (fluid-attenuated inversion recovery (FLAIR) vascular hyperintensities (FVHs), collateralization on dynamic 4D angiograms) and investigate its relation to ischemic lesion size and growth.
  
  
  METHODS
  In 28 patients with posterior cerebral artery (PCA) and 10 patients with basilar artery (BA) occlusion, MRI findings were analyzed, with emphasis on distal FVH and collateralization on dynamic 4D angiograms.
  
  
  RESULTS
  In PCA occlusion, distal FVH was observed in 18/29 (62.1%), in BA occlusion, in 8/10 (80%) cases. Collateralization on dynamic 4D angiograms was graded 1 in 8 (27.6%) patients, 2 in 1 (3.4%) patient, 3 in 12 (41.4%) patients, and 4 in 8 (27.6%) patients with PCA occlusion and 0 in 1 (10%) patient, 2 in 3 (30%) patients, 3 in 1 (10%) patient, and 4 in 5 (50%) patients with BA occlusion. FVH grade showed neither correlation with initial or follow-up diffusion-weighted image (DWI) lesion size nor DWI-perfusion-weighted imaging (PWI) mismatch ratio. Collateralization on dynamic 4D angiograms correlated inversely with initial DWI lesion size and moderately with the DWI-(PWI) mismatch ratio. The combination of distal FVH and collateralization grade on dynamic 4D angiograms correlated inversely with initial as well as follow-up DWI lesion size and highly with the DWI-PWI mismatch ratio.
  
  
  CONCLUSIONS
  In posterior circulation occlusion, FVH is a frequent finding, but its prognostic value is limited. Dynamic 4D angiograms are advantageous to examine and graduate collateral blood flow. The combination of both parameters results in an improved characterization of collateral blood flow and might have prognostic relevance.
authors.affiliation: Department of Neuroradiology, Universitätsmedizin Mannheim, University of Heidelberg, Theodor-Kutzer-Ufer 1-3, 68167, Mannheim, Germany, Alex.Foerster@umm.de.
authors.forename: Alex
authors.initials: A
authors.lastname: Förster
authors.forename: Holger
authors.initials: H
authors.lastname: Wenz
authors.forename: Hans Ulrich
authors.initials: HU
authors.lastname: Kerl
authors.forename: Mansour
authors.initials: M
authors.lastname: Al-Zghloul
authors.forename: Sonia
authors.initials: S
authors.lastname: Habich
authors.forename: Christoph
authors.initials: C
authors.lastname: Groden
mesh_terms: D000368:Aged; D000792:Angiography / Q000379:methods; D002560:Cerebrovascular Circulation; D002561:Cerebrovascular Disorders / Q000175:diagnosis* / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D012189:Retrospective Studies