title: Direct coronary motion extraction from a 2D fat image navigator for prospectively gated coronary MR angiography.
abstract: OBJECTIVE
  Direct 2D tracking of cardiac motion may provide superior respiratory navigator gating for coronary magnetic resonance angiography compared to conventional liver-diaphragm navigators. However, additional 2D processing for motion extraction is unsuitable for real-time prospective gating. In this work, a 2D fat-selective image navigator, which delineates the epicardial fat surrounding coronary arteries, is developed to directly monitor epicardial fat motion at every heartbeat in real-time for prospective gating.
  
  
  METHODS
  The proposed navigator is incorporated into a real-time interactive software that allows rapid setup and efficient motion extraction, and runs on standard clinical hardware without any additional dedicated components for processing. The proposed 2D cardiac fat image navigator was compared with the conventional 1D diaphragm navigator in free-breathing b-SSFP coronary MRAs in 12 healthy volunteers at 1.5T.
  
  
  RESULTS
  Real-time motion extraction from 2D cardiac fat navigator images was feasible within 20 ms, enabling successful prospectively gated coronary magnetic resonance angiographies in all subjects. Compared to 1D diaphragmatic navigator, 2D fat image navigator reduced scan time by 38% (P < 0.0005), and significantly improved vessel sharpness, myocardial suppression, and image quality (P < 0.05).
  
  
  CONCLUSIONS
  This demonstrates the feasibility of a 3D SSFP coronary magnetic resonance angiography sequence using a 2D epicardial fat image as a navigator for real-time prospective motion tracking.
authors.affiliation: Department of Biomedical Engineering, Cornell University, Ithaca, New York, USA; Department of Radiology, Weill Cornell Medical College, New York, New York, USA.
authors.forename: Keigo
authors.initials: K
authors.lastname: Kawaji
authors.forename: Pascal
authors.initials: P
authors.lastname: Spincemaille
authors.forename: Thanh D
authors.initials: TD
authors.lastname: Nguyen
authors.forename: Nandadeepa
authors.initials: N
authors.lastname: Thimmappa
authors.forename: Mitchell A
authors.initials: MA
authors.lastname: Cooper
authors.forename: Martin R
authors.initials: MR
authors.lastname: Prince
authors.forename: Yi
authors.initials: Y
authors.lastname: Wang
mesh_terms: D000328:Adult; D017023:Coronary Angiography / Q000379:methods*; D003331:Coronary Vessels / Q000502:physiology; D003964:Diaphragm / Q000502:physiology; D006801:Humans; D018810:Magnetic Resonance Angiography / Q000379:methods*; D012984:Software