title: Arterial spin-labeling MR imaging measurements of timing parameters in patients with a carotid artery occlusion.
abstract: OBJECTIVE
  Arterial spin-labeling (ASL) with image acquisition at multiple delay times can be exploited in perfusion MR imaging to visualize and quantify the temporal dynamics of arterial blood inflow. In this study, we investigated the consequences of an internal carotid artery (ICA) occlusion and collateral blood flow on regional timing parameters.
  
  
  METHODS
  Seventeen functionally independent patients with a symptomatic ICA occlusion (15 men, 2 women; mean age, 57 years) and 29 sex- and age-matched control subjects were investigated. ASL at multiple delay times was used to quantify regional cerebral blood flow (CBF) and the transit and trailing edge times (arterial timing parameters) reflecting, respectively, the beginning and end of the labeled bolus. Intra-arterial digital subtraction angiography and MR angiography were used to grade collaterals.
  
  
  RESULTS
  In the hemisphere ipsilateral to the ICA occlusion, the CBF was lower in the anterior frontal (31 +/- 4 versus 47 +/- 3 mL/min/100 g, P < .01), posterior frontal (39 +/- 4 versus 55 +/- 2 mL/min/100 g, P < .01), and frontal parietal region (49 +/- 3 versus 61 +/- 3 mL/min/100 g, P = .04) than that in control subjects. The trailing edge of the frontal-parietal region was longer in the hemisphere ipsilateral to the ICA occlusion compared with that in control subjects (2225 +/- 167 versus 1593 +/- 35 ms, P < .01). In patients with leptomeningeal collateral flow, the trailing edge was longer in the anterior frontal region (2436 +/- 275 versus 1648 +/- 201 ms, P = .03) and shorter in the occipital region (1815 +/- 128 versus 2388 +/- 203 ms, P = .04), compared with patients without leptomeningeal collaterals.
  
  
  CONCLUSIONS
  Regional assessment of timing parameters with ASL may provide valuable information on the cerebral hemodynamic status. In patients with leptomeningeal collaterals, the most impaired territory was found in the frontal lobe.
authors.affiliation: Department of Radiology, University Medical Center Utrecht, Utrecht, the Netherlands. r.p.h.bokkers@umcutrecht.nl
authors.forename: R P H
authors.initials: RP
authors.lastname: Bokkers
authors.forename: P J
authors.initials: PJ
authors.lastname: van Laar
authors.forename: K C C
authors.initials: KC
authors.lastname: van de Ven
authors.forename: L J
authors.initials: LJ
authors.lastname: Kapelle
authors.forename: C J M
authors.initials: CJ
authors.lastname: Klijn
authors.forename: J
authors.initials: J
authors.lastname: Hendrikse
mesh_terms: D000368:Aged; D015901:Angiography, Digital Subtraction; D001783:Blood Flow Velocity / Q000502:physiology; D001921:Brain / Q000098:blood supply*; D002343:Carotid Artery, Internal; D016893:Carotid Stenosis / Q000175:diagnosis*; D003097:Collateral Circulation / Q000502:physiology; D004292:Dominance, Cerebral / Q000502:physiology; D005260:Female; D005625:Frontal Lobe / Q000098:blood supply; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D018810:Magnetic Resonance Angiography; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009778:Occipital Lobe / Q000098:blood supply; D010296:Parietal Lobe / Q000098:blood supply; D012039:Regional Blood Flow / Q000502:physiology; D012680:Sensitivity and Specificity; D013113:Spin Labels
chemical_list: D013113:Spin Labels