title: MR flow mapping in coronary artery bypass grafts: a validation study with Doppler flow measurements.
abstract: OBJECTIVE
  To validate fast magnetic resonance (MR) flow mapping with intravascular Doppler flow measurements in vitro and in patients with nonstenotic and stenotic coronary artery bypass grafts.
  
  
  METHODS
  MR and Doppler flow measurements were performed in a small-diameter flow phantom with physiologic flow conditions and at baseline and during adenosine stress in 27 grafts in 23 patients, who were scheduled for cardiac catheterization. At invasive analysis, the grafts were divided into those with stenosis of less than 50% (nonstenotic) and those with stenosis greater than or equal to 50% (stenotic). In vitro velocity values and velocity values in nonstenotic and stenotic grafts were compared with linear regression analysis, and the in vitro interstudy variability was determined.
  
  
  RESULTS
  Excellent correlations in average peak velocity (r = 0.99, P <.001) and diastolic peak velocity (r = 0.99, P <.001) were demonstrated in vitro between MR and Doppler flow measurements, with less than 5% interstudy variability. MR and Doppler flow measurements revealed good correlations in peak velocity and velocity reserve both in nonstenotic (n = 20) (average peak velocity: r = 0.81, P <.001; diastolic peak velocity: r = 0.83, P <.001; velocity reserve: r = 0.56, P =.010) and stenotic (n = 7) (average peak velocity: r = 0.83, P <.001; diastolic peak velocity: r = 0.78, P =.001; velocity reserve: r = 0.70, P =.078) grafts.
  
  
  CONCLUSIONS
  Fast MR flow mapping provides noninvasive measures of peak velocity and velocity reserve, which closely correlate with Doppler values both in vitro and in nonstenotic and stenotic grafts.
authors.affiliation: Dept of Cardiology, Leiden Univ Medical Center, Albinusdreef 2, 2333 ZA Leiden, the Netherlands.
authors.forename: Susan E
authors.initials: SE
authors.lastname: Langerak
authors.forename: Patrik
authors.initials: P
authors.lastname: Kunz
authors.forename: Hubert W
authors.initials: HW
authors.lastname: Vliegen
authors.forename: J Wouter
authors.initials: JW
authors.lastname: Jukema
authors.forename: Aeilko H
authors.initials: AH
authors.lastname: Zwinderman
authors.forename: Paul
authors.initials: P
authors.lastname: Steendijk
authors.forename: Hildo J
authors.initials: HJ
authors.lastname: Lamb
authors.forename: Ernst E
authors.initials: EE
authors.lastname: van der Wall
authors.forename: Albert
authors.initials: A
authors.lastname: de Roos
mesh_terms: D000241:Adenosine; D000368:Aged; D001783:Blood Flow Velocity / Q000502:physiology; D001026:Coronary Artery Bypass; D003326:Coronary Circulation; D003331:Coronary Vessels / Q000000981:diagnostic imaging* / Q000502:physiology*; D015150:Echocardiography, Doppler; D005260:Female; D006083:Graft Occlusion, Vascular / Q000175:diagnosis* / Q000000981:diagnostic imaging; D006801:Humans; D007091:Image Processing, Computer-Assisted; D016014:Linear Models; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D019047:Phantoms, Imaging; D014654:Vascular Patency
chemical_list: D000241:Adenosine