title: Optimal systolic and diastolic image reconstruction windows for coronary 256-slice CT angiography.
abstract: OBJECTIVE
  The aims of this study were to determine the optimal image reconstruction intervals for the systolic and diastolic phases of coronary computed tomographic angiography on 256-slice computed tomography and to assess their associated motion artifacts.
  
  
  METHODS
  One hundred twenty-six patients were recruited (mean heart rate [HR], 72.1 beats/min; heart rate variability, 1.3 beats/min). Twenty data sets were reconstructed in 5% steps through 0% to 95% of the R-R interval. Two reviewers discriminated optimal reconstruction intervals for 15 segments distributed in three coronary arteries on the basis of motion artifacts, which were graded from 1 (no motion artifacts) to 4 (severe motion artifacts preventing diagnosis). Patients were then stratified into four HR groups for motion score comparison according to the results of a correlation analysis of HR and motion scores.
  
  
  RESULTS
  The optimal systolic and diastolic reconstruction intervals were 44.4 ± 3.8% and 77.4 ± 3.7%, respectively. The mean motion scores for systolic, diastolic, and combined systolic and diastolic (S+D) reconstructions were 1.8 ± 0.3, 1.8 ± 0.5, and 1.5 ± 0.3, respectively. Combined S+D reconstruction improved diagnostic evaluability to 100% and showed fewer motion artifacts compared to single-phase reconstructions for all HR ranges (S+D vs systolic, P < .05 for HR < 85 beats/min; S+D vs diastolic, P < .05 for HRs of 73-84 beats/min). For HRs of 60 to 72 beats/min, motion artifacts were significantly lower for diastole (1.6 ± 0.3) than systole (1.8 ± 0.4) (P < .001), and vice versa for HRs of 73 to 84 beats/min (1.7 ± 0.3 for systole vs 2.0 ± 0.5 for diastole, P < .01).
  
  
  CONCLUSIONS
  Optimal systolic and diastolic reconstruction intervals were determined for this 256-slice coronary computed tomographic angiographic study. Combined reconstruction showed fewer motion artifacts compared to single-phase reconstruction. In conclusion, 256-slice computed tomography has the potential to improve the diagnostic accuracy of coronary computed tomographic angiography.
authors.affiliation: Department of Imaging and Interventional Radiology, The Chinese University of Hong Kong, Hong Kong.
authors.forename: Greta S P
authors.initials: GS
authors.lastname: Mok
authors.forename: Ching-Ching
authors.initials: CC
authors.lastname: Yang
authors.forename: Liang-Kuang
authors.initials: LK
authors.lastname: Chen
authors.forename: Kun-Mu
authors.initials: KM
authors.lastname: Lu
authors.forename: Wei-Yip
authors.initials: WY
authors.lastname: Law
authors.forename: Tung-Hsin
authors.initials: TH
authors.lastname: Wu
mesh_terms: D000465:Algorithms; D017023:Coronary Angiography / Q000379:methods*; D003324:Coronary Artery Disease / Q000150:complications* / Q000000981:diagnostic imaging*; D003971:Diastole; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011856:Radiographic Image Enhancement / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013599:Systole; D014057:Tomography, X-Ray Computed / Q000379:methods*; D018487:Ventricular Dysfunction, Left / Q000175:diagnosis* / Q000209:etiology*