title: Dual-source computed tomography angiography image quality in patients with fast heart rates.
abstract: BACKGROUND
  Dual-source computed tomography (DSCT) provides diagnostic quality images of the coronary arteries over a wide range of heart rates (HRs). Current dose reduction techniques, including electrocardiographic (ECG) dose modulation and prospective triggering, are optimized for use in patients with relatively slow (<70 beats/min) HRs by limiting radiation dose to the ideal phases of image acquisition.
  
  
  OBJECTIVE
  We evaluated coronary vessel image quality (IQ) at different reconstruction phases in patients with fast HRs (>80 beats/min) to assess potential feasibility of prospective triggering techniques on DSCT.
  
  
  METHODS
  Patients (n=101) underwent 64-slice DSCT with retrospective ECG-gating without beta-blocker premedication. Image reconstructions were performed at 10% R-R wave phase intervals (0%-90%). Patients were grouped by mean HR: group A, <60 beats/min (n=22); group B, 60-80 beats/min (n=57); group C, >80 beats/min (n=22). Coronary artery IQ was assessed by 2 readers in consensus on a 5-point scale.
  
  
  RESULTS
  Optimal IQ occurred at 70% phase for all arteries in groups A and B. In group C, optimal IQ occurred at 30% and 40% phases. The 70% phase achieved diagnostic IQ in 97% of group A and 86% of group B. A widened reconstruction window (30%-50%) was necessary for diagnostic IQ in a similar high proportion (84%) of group C.
  
  
  CONCLUSIONS
  Optimal IQ occurs during late-systolic phases for patients with fast HRs (>80 beats/min). Late-systolic phase prospective triggering is potentially feasible in these patients; however, given the widened reconstruction windows required, a higher radiation dose may be required compared with patients with slower HRs (<80 beats/min).
authors: Department of Radiology, New York University School of Medicine, 530 First Avenue HCC-C48, New York, NY 10016, USA. srichai@alum.mit.edu
authors: Monvadi B
authors: MB
authors: Srichai
authors: Elizabeth M
authors: EM
authors: Hecht
authors: Danny
authors: D
authors: Kim
authors: James
authors: J
authors: Babb
authors: Jessica
authors: J
authors: Bod
authors: Jessica
authors: J
authors: Bodd
authors: Jill E
authors: JE
authors: Jacobs
mesh_terms: D016477:Artifacts; D055424:Cardiac-Gated Imaging Techniques / Q000379:methods*; D017023:Coronary Angiography / Q000379:methods*; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging*; D005260:Female; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D011856:Radiographic Image Enhancement / Q000379:methods*; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*