title: Prospective motion correction and selective reacquisition using volumetric navigators for vessel-encoded arterial spin labeling dynamic angiography.
abstract: The aim of this study was to improve robustness to motion in a vessel-encoded angiography sequence used for patient scans. The sequence is particularly sensitive to motion between imaging segments, which causes ghosting and blurring that propagates to the final angiogram.
  
  
  
  Volumetric echo planar imaging (EPI) navigators acquired in 275 ms were inserted after the imaging readout in a vessel-encoded pseudo-continuous arterial spin labeling (VEPCASL) sequence. The effects of movement between segments on the images were tested with phantom experiments. Deliberate motion experiments with healthy volunteers were performed to compare prospective motion correction (PMC) with reacquisition versus no correction.
  
  
  
  In scans without motion, the addition of the EPI navigator to the sequence did not affect the quality of the angiograms in comparison with the original sequence. PMC and reacquisition improved the visibility of vessels in the angiograms compared with the scans without correction. The reacquisition strategy was shown to be important for complete correction of imaging artifacts.
  
  
  
  We have demonstrated an effective method to correct motion in vessel-encoded angiography. For reacquisition of 15 segments, the technique requires approximately 30 s of additional scanning (∼25%). Magn Reson Med 76:1420-1430, 2016. © 2015 International Society for Magnetic Resonance in Medicine.
authors.affiliation: FMRIB Centre, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom. robert.frost@ndcn.ox.ac.uk.
authors.forename: Robert
authors.initials: R
authors.lastname: Frost
authors.affiliation: Oxford Centre for Clinical Magnetic Resonance Research, Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom.
authors.forename: Aaron T
authors.initials: AT
authors.lastname: Hess
authors.affiliation: FMRIB Centre, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom.
authors.forename: Thomas W
authors.initials: TW
authors.lastname: Okell
authors.affiliation: FMRIB Centre, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom.|Institute of Biomedical Engineering, University of Oxford, Oxford, United Kingdom.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Chappell
authors.affiliation: A. A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, Massachusetts, USA.|Department of Radiology, Harvard Medical School, Boston, Massachusetts, USA.
authors.forename: M Dylan
authors.initials: MD
authors.lastname: Tisdall
authors.affiliation: A. A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, Massachusetts, USA.|Department of Radiology, Harvard Medical School, Boston, Massachusetts, USA.
authors.forename: André J W
authors.initials: AJ
authors.lastname: van der Kouwe
authors.affiliation: FMRIB Centre, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom.
authors.forename: Peter
authors.initials: P
authors.lastname: Jezzard
mesh_terms: D000465:Algorithms; D016477:Artifacts; D055424:Cardiac-Gated Imaging Techniques / Q000379:methods*; D002339:Carotid Arteries / Q000000981:diagnostic imaging*; D002533:Cerebral Angiography / Q000379:methods*; D017352:Echo-Planar Imaging / Q000379:methods; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods*; D018810:Magnetic Resonance Angiography / Q000379:methods*; D009038:Motion; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013113:Spin Labels; D013382:Subtraction Technique
chemical_list: D013113:Spin Labels
keywords: magnetic resonance angiography; prospective motion correction; pseudo-continuous arterial spin labeling; reacquisition; vessel-encoded angiography; volumetric navigator