title: SENSE or k-MAG to accelerate free breathing navigator-guided coronary MR angiography.
abstract: OBJECTIVE
  The purpose of this study was to assess the relative merits of reducing the scanning time of navigator-guided (NAV) coronary MR angiography by including, both independently and in combination, two time-saving strategies: k-space weighted motion-adapted gating (k-MAG) and sensitivity encoding (SENSE, factor = 2).
  
  
  METHODS
  Coronary arteries of 21 healthy subjects were imaged with four NAV MR angiography sequences: conventional NAV sequence, NAV with the addition of SENSE, NAV with the addition of k-MAG, and NAV with a combination of SENSE and k-MAG. All imaging parameters including the magnetization preparation schemes, prescribed spatial resolution, and acquisition duration per R-R interval were identical for all techniques. The total scanning time, navigator efficiency, visible length of the coronary artery, and subjective image quality were used as metrics for evaluating the performance of the techniques.
  
  
  RESULTS
  The results show that the addition of k-MAG to NAV coronary MR angiography (with or without SENSE) improved scan efficiency and decreased scanning time by an average of 17% without compromising the length of coronary artery visible or the image quality. The addition of SENSE to the NAV technique (with or without k-MAG) reduces the scanning time by an average of 50%.
  
  
  CONCLUSIONS
  While the average image quality of coronary arteries was unaffected by the addition of k-MAG to navigator techniques, there was a slight reduction in image quality scores for the navigator sequence with SENSE. Identification of the proximal coronary arteries was not hampered by the addition of k-MAG, SENSE, or both to the NAV coronary MR angiography sequence.
authors.affiliation: Department of Radiology, St. Luke's Episcopal Hospital and Texas Heart Institute and Baylor College of Medicine, 6720 Bertner Ave., MC 2-256, Houston, TX 77030, USA. raja.muthupillai@philips.com
authors.forename: Raja
authors.initials: R
authors.lastname: Muthupillai
authors.forename: Jouke
authors.initials: J
authors.lastname: Smink
authors.forename: Steve
authors.initials: S
authors.lastname: Hong
authors.forename: Roshan
authors.initials: R
authors.lastname: Ravindran
authors.forename: Vei Vei
authors.initials: VV
authors.lastname: Lee
authors.forename: Scott D
authors.initials: SD
authors.lastname: Flamm
mesh_terms: D000328:Adult; D000368:Aged; D017023:Coronary Angiography / Q000379:methods*; D005260:Female; D006801:Humans; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012119:Respiration; D013997:Time Factors