title: The Effect of Heart Rate on Exposure Window and Best Phase for Stress Perfusion Computed Tomography: Lessons From the CORE320 Study.
abstract: OBJECTIVE
  The aim of this study is to evaluate the effect of heart rate on exposure window, best phase, and image quality for stress computed tomography perfusion (CTP) in the CORE320 study.
  
  
  METHODS
  The CTP data sets were analyzed to determine the best phase for perfusion analysis. A predefined exposure window covering 75% to 95% of the R-R cycle was used.
  
  
  RESULTS
  Of the 368 patients included in the analysis, 93% received oral β blockade before the rest scan. The median heart rate during the stress acquisition was 69 bpm (interquartile range [IQR], 60-77). The median best phase was 81% (IQR, 76-90), and length of exposure window was 22% (IQR, 19-24). The best phase was significantly later in the cardiac cycle with higher heart rates (P < 0.001), and higher heart rates resulted in a small, but higher number of poor quality scans (6%, P < 0.001). The median effective dose of the stress scan was 5.3 mSv (IQR, 3.8-6.1).
  
  
  CONCLUSIONS
  Stress myocardial CTP imaging can be performed using prospective electrocardiography triggering, an exposure window of 75% to 95%, and β-blockade resulting in good or excellent image quality in the majority (80%) of patients while maintaining a low effective radiation dose.
authors.affiliation: From the *Toshiba Medical Systems Corporation, Tokyo, Japan; †Toshiba Medical Systems, Europe, Zoetermeer, The Netherlands; ‡Division of Cardiology, Department of Medicine, Johns Hopkins University, School of Medicine, Baltimore, MD; §Toshiba Medical Research Institute, Vernon Hills, IL; and ∥Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD.
authors.forename: Chloe
authors.initials: C
authors.lastname: Steveson
authors.forename: Joanne D
authors.initials: JD
authors.lastname: Schuijf
authors.forename: Andrea L
authors.initials: AL
authors.lastname: Vavere
authors.forename: Richard T
authors.initials: RT
authors.lastname: Mather
authors.forename: Teresa
authors.initials: T
authors.lastname: Caton
authors.forename: Vishal
authors.initials: V
authors.lastname: Mehra
authors.forename: Aisha
authors.initials: A
authors.lastname: Betoko
authors.forename: Christopher
authors.initials: C
authors.lastname: Cox
authors.forename: Joao Ac
authors.initials: JA
authors.lastname: Lima
authors.forename: Richard T
authors.initials: RT
authors.lastname: George
mesh_terms: D058671:Adrenergic beta-1 Receptor Antagonists; D000368:Aged; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging* / Q000503:physiopathology; D004562:Electrocardiography / Q000379:methods / Q000706:statistics & numerical data; D005080:Exercise Test; D005260:Female; D006339:Heart Rate; D006801:Humans; D008297:Male; D008790:Metoprolol; D008875:Middle Aged; D011446:Prospective Studies; D014057:Tomography, X-Ray Computed / Q000379:methods* / Q000706:statistics & numerical data
chemical_list: D058671:Adrenergic beta-1 Receptor Antagonists; D008790:Metoprolol