title: Prediction of infarction and reperfusion in stroke by flow- and volume-weighted collateral signal in MR angiography.
abstract: OBJECTIVE
  In proximal anterior circulation occlusive strokes, collateral flow is essential for good outcome. Collateralized vessel intensity in TOF- and contrast-enhanced MRA is variable due to different acquisition methods. Our purpose was to quantify collateral supply by using flow-weighted signal in TOF-MRA and blood volume-weighted signal in contrast-enhanced MRA to determine each predictive contribution to tissue infarction and reperfusion.
  
  
  METHODS
  Consecutively (2009-2013), 44 stroke patients with acute proximal anterior circulation occlusion met the inclusion criteria with TOF- and contrast-enhanced MRA and penumbral imaging. Collateralized vessels in the ischemic hemisphere were assessed by TOF- and contrast-enhanced MRA using 2 methods: 1) visual 3-point collateral scoring, and 2) collateral signal quantification by an arterial atlas-based collateral index. Collateral measures were tested by receiver operating characteristic curve and logistic regression against 2 imaging end points of tissue-outcome: final infarct volume and percentage of penumbra saved.
  
  
  RESULTS
  Visual collateral scores on contrast-enhanced MRA but not TOF were significantly higher in patients with good outcome. Visual collateral scoring on contrast-enhanced MRA was the best rater-based discriminator for final infarct volume < 90 mL (area under the curve, 0.81; P < .01) and percentage of penumbra saved >50% (area under the curve, 0.67; P = .04). Atlas-based collateral index of contrast-enhanced MRA was the overall best independent discriminator for final infarct volume of <90 mL (area under the curve, 0.94; P < .01). Atlas-based collateral index combining the signal of TOF- and contrast-enhanced MRA was the overall best discriminator for effective reperfusion (percentage of penumbra saved >50%; area under the curve, 0.89; P < .001).
  
  
  CONCLUSIONS
  Visual scoring of contrast-enhanced but not TOF-MRA is a reliable predictor of infarct outcome in stroke patients with proximal arterial occlusion. By atlas-based collateral assessment, TOF- and contrast-enhanced MRA both contain predictive signal information for penumbral reperfusion. This could improve risk stratification in further studies.
authors.affiliation: From the Departments of Diagnostic and Interventional Neuroradiology (M.E., L.B., S.S., J.F., A.K.).
authors.forename: M
authors.initials: M
authors.lastname: Ernst
authors.affiliation: Department of Radiology and Hotchkiss Brain Institute (N.D.F.), University of Calgary, Calgary, Canada.
authors.forename: N D
authors.initials: ND
authors.lastname: Forkert
authors.affiliation: From the Departments of Diagnostic and Interventional Neuroradiology (M.E., L.B., S.S., J.F., A.K.).
authors.forename: L
authors.initials: L
authors.lastname: Brehmer
authors.affiliation: Neurology (G.T.), University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: G
authors.initials: G
authors.lastname: Thomalla
authors.affiliation: From the Departments of Diagnostic and Interventional Neuroradiology (M.E., L.B., S.S., J.F., A.K.).
authors.forename: S
authors.initials: S
authors.lastname: Siemonsen
authors.affiliation: From the Departments of Diagnostic and Interventional Neuroradiology (M.E., L.B., S.S., J.F., A.K.).
authors.forename: J
authors.initials: J
authors.lastname: Fiehler
authors.affiliation: From the Departments of Diagnostic and Interventional Neuroradiology (M.E., L.B., S.S., J.F., A.K.) Department of Neuroradiology (A.K.), University of Luebeck, Luebeck, Germany. a.kemmling@uke.de.
authors.forename: A
authors.initials: A
authors.lastname: Kemmling
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001157:Arterial Occlusive Diseases / Q000175:diagnosis*; D020520:Brain Infarction / Q000175:diagnosis*; D003097:Collateral Circulation / Q000502:physiology; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D016015:Logistic Models; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012372:ROC Curve; D015424:Reperfusion; D020521:Stroke / Q000175:diagnosis* / Q000503:physiopathology*