title: Evaluation of three-dimensional navigator-gated whole heart MR coronary angiography: the importance of systolic imaging in subjects with high heart rates.
abstract: OBJECTIVE
  To evaluate the influence of heart rate (HR) on magnetic resonance coronary angiography (MRCA) image quality in diastolic and systolic phases.
  
  
  METHODS
  Twenty-seven healthy volunteers (9 men; 33+/-9 years, HR 53-110 bpm), were evaluated with the electrocardiography and three-dimensional navigator-gating MRCA in a 1.5-T MR scanner (Avanto, Siemens) in diastolic and systolic phases (steady-state free precession; TR/TE/flip angle=3.2 ms/1.6 ms/90 degrees). The timing of scanning was individually adapted to the cardiac rest periods obtained in the prescanning, by visually identifying when the movement of right coronary artery was minimized during diastole and systole. Images of two phases were side-by-side compared on a four-point scale (from 1=poor to 4=excellent visibility; score of 3 or 4 as diagnostic).
  
  
  RESULTS
  Of 13 subjects with HR < or =65 bpm (low HR group, mean 59.8+/-4.9 bpm, range 53-65), the image quality scores were significantly better than that with higher heart rates (73.9+/-9.0 bpm, range 68-110) in diastolic MRCA. The image quality was significantly improved during systole in high HR group. Overall, 91.3% of low HR group had MRCA image of diagnostic quality acquired at diastole, while 88.3% of high HR group had diagnostic images at systole by segmental analysis (p=NS).
  
  
  CONCLUSIONS
  MRCA at systole offered superior quality in patients with high heart rates.
authors.affiliation: Department of Diagnostic Imaging, Kyoto University Graduate School of Medicine, 54 Shogoinkawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan.
authors.forename: Yen-Wen
authors.initials: YW
authors.lastname: Wu
authors.forename: Eiji
authors.initials: E
authors.lastname: Tadamura
authors.forename: Masaki
authors.initials: M
authors.lastname: Yamamuro
authors.forename: Shotaro
authors.initials: S
authors.lastname: Kanao
authors.forename: Kazuki
authors.initials: K
authors.lastname: Nakayama
authors.forename: Kaori
authors.initials: K
authors.lastname: Togashi
mesh_terms: D000328:Adult; D016477:Artifacts; D017023:Coronary Angiography / Q000295:instrumentation / Q000379:methods*; D003331:Coronary Vessels / Q000033:anatomy & histology*; D003971:Diastole; D005260:Female; D006339:Heart Rate; D006801:Humans; D007089:Image Enhancement / Q000295:instrumentation / Q000379:methods*; D018810:Magnetic Resonance Angiography / Q000295:instrumentation / Q000379:methods*; D008297:Male; D009068:Movement; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013599:Systole