title: Comparison of respiratory suppression methods and navigator locations for MR coronary angiography.
abstract: OBJECTIVE
  Currently, breath-holding during MR coronary angiography is used to minimize respiratory motion. This technique requires patient cooperation and is associated with slice registration errors. The goal of this study was to evaluate alternative non-breath-hold techniques for MR coronary angiography during free breathing.
  
  
  METHODS
  Subjects underwent MR coronary angiography using an ECG-gated, fat-suppressed, segmented K-space, gradient-echo sequence. Images were obtained during free breathing using both real-time navigator gating and respiratory bellows gating. These were compared with images obtained during conventional breath-holding. The optimal navigator location (diaphragmatic or cardiac) was also studied. Image quality, registration error, and scan time were measured for all scans.
  
  
  RESULTS
  Navigator gating for MR coronary angiography during free breathing resulted in image quality equivalent to that obtained during breath-holding and was superior to that obtained with respiratory bellows gating (p < .04). Also, navigator gating reduced registration errors by 75% compared with breath-holding (p < .01) and did not increase scan time. No significant differences in the parameters measured were observed among the different navigator locations.
  
  
  CONCLUSIONS
  Real-time navigator gating for MR coronary angiography during free breathing achieved image quality and scan time equivalent to breath-holding. Navigator gating also significantly reduced registration error. Compared with breath-holding and respiratory bellows gating, navigator gating during free breathing is a more optimal approach for suppression of respiratory motion during MR coronary angiography.
authors.affiliation: Department of Medicine, Charles A. Dana Research Institute, Boston, MA, USA.
authors.forename: M V
authors.initials: MV
authors.lastname: McConnell
authors.forename: V C
authors.initials: VC
authors.lastname: Khasgiwala
authors.forename: B J
authors.initials: BJ
authors.lastname: Savord
authors.forename: M H
authors.initials: MH
authors.lastname: Chen
authors.forename: M L
authors.initials: ML
authors.lastname: Chuang
authors.forename: R R
authors.initials: RR
authors.lastname: Edelman
authors.forename: W J
authors.initials: WJ
authors.lastname: Manning
mesh_terms: D000328:Adult; D000368:Aged; D016477:Artifacts; D003331:Coronary Vessels / Q000033:anatomy & histology*; D004562:Electrocardiography; D005069:Evaluation Studies as Topic; D005260:Female; D006801:Humans; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012119:Respiration; D013997:Time Factors