title: Nonenhanced arterial spin labeled carotid MR angiography using three-dimensional radial balanced steady-state free precession imaging.
abstract: OBJECTIVE
  To optimize and preliminarily evaluate a three-dimensional (3D) radial balanced steady-state free precession (bSSFP) arterial spin labeled (ASL) sequence for nonenhanced MR angiography (MRA) of the extracranial carotid arteries.
  
  
  METHODS
  The carotid arteries of 13 healthy subjects and 2 patients were imaged on a 1.5 Tesla MRI system using an undersampled 3D radial bSSFP sequence providing a scan time of ∼4 min and 1 mm(3) isotropic resolution. A hybridized scheme that combined pseudocontinuous and pulsed ASL was used to maximize arterial coverage. The impact of a post label delay period, the sequence repetition time, and radiofrequency (RF) energy configuration of pseudocontinuous labeling on the display of the carotid arteries was assessed with contrast-to-noise ratio (CNR) measurements. Faster, higher undersampled 2 and 1 min scans were tested.
  
  
  RESULTS
  Using hybridized ASL MRA and a 3D radial bSSFP trajectory, arterial CNR was maximized with a post label delay of 0.2 s, repetition times ≥ 2.5 s (P < 0.05), and by eliminating RF energy during the pseudocontinuous control phase (P < 0.001). With higher levels of undersampling, the carotid arteries were displayed in ≤ 2 min.
  
  
  CONCLUSIONS
  Nonenhanced MRA using hybridized ASL with a 3D radial bSSFP trajectory can display long lengths of the carotid arteries with 1 mm(3) isotropic resolution.
authors.affiliation: Department of Radiology, NorthShore University HealthSystem, Evanston, Illinois, USA; The University of Chicago Pritzker School of Medicine, Chicago, Illinois, USA.
authors.forename: Ioannis
authors.initials: I
authors.lastname: Koktzoglou
authors.forename: Joel R
authors.initials: JR
authors.lastname: Meyer
authors.forename: William J
authors.initials: WJ
authors.lastname: Ankenbrandt
authors.forename: Shivraman
authors.initials: S
authors.lastname: Giri
authors.forename: Davide
authors.initials: D
authors.lastname: Piccini
authors.forename: Michael O
authors.initials: MO
authors.lastname: Zenge
authors.forename: Oisin
authors.initials: O
authors.lastname: Flanagan
authors.forename: Tina
authors.initials: T
authors.lastname: Desai
authors.forename: NavYash
authors.initials: N
authors.lastname: Gupta
authors.forename: Robert R
authors.initials: RR
authors.lastname: Edelman
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D002339:Carotid Arteries / Q000473:pathology*; D016893:Carotid Stenosis / Q000473:pathology*; D003287:Contrast Media; D005260:Female; 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*; D008297:Male; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013113:Spin Labels
chemical_list: D003287:Contrast Media; D013113:Spin Labels
keywords: angiography; arterial spin labeling; carotid; nonenhanced; radial