title: Coronary computed tomography angiography during arrhythmia: Radiation dose reduction with prospectively ECG-triggered axial and retrospectively ECG-gated helical 128-slice dual-source CT.
abstract: BACKGROUND
  Arrhythmia during coronary computed tomography angiography (coronary CTA) acquisition increases the risk of nondiagnostic segments and high radiation exposure. An advanced arrhythmia rejection algorithm for prospectively electrocardiogram (ECG)-triggered axial scans using dual-source CT (DSCT) examinations has recently been reported.
  
  
  OBJECTIVE
  We compared image quality and effective dose at DSCT examinations using prospectively ECG-triggered axial scanning with advanced arrhythmia rejection software (PT-AAR) versus retrospectively ECG-gated helical scanning with tube-current modulation (RG-TCM) during arrhythmia.
  
  
  METHODS
  This was a retrospective case-control study of 90 patients (43 PT-AAR, 47 RG-TCM) with arrhythmia (defined as heart rate variability [HRV] > 10 beats/min during data acquisition) referred for physician-supervised coronary CTA between April 2010 and September 2011. A subset of 22 cases matched for body mass index, HR, HRV, and other scan parameters was identified. Subjective image quality (4-point scale) and effective dose (dose length product method) were compared.
  
  
  RESULTS
  PT-AAR was associated with lower effective dose than RG-TCM (4.1 vs 12.6 mSv entire cohort and 4.3 vs 9.1 mSv matched controls; both P < 0.01). Image quality scores were excellent in both groups (3.9 PT-AAR vs 3.6 RG-TCM) and nondiagnostic segment rates were low (0.1% vs 0.6%). Significantly higher image quality scores were found with PT-AAR in the entire cohort (P < 0.05), and in matched controls with high HRV > 28 beats/min (P < 0.05).
  
  
  CONCLUSIONS
  In patients with variable heart rates, prospectively ECG-triggered axial DSCT with arrhythmia rejection algorithm is feasible and can decrease radiation exposure by ∼50% versus retrospectively ECG-gated helical DSCT, with preserved image quality.
authors.affiliation: Cardiac MR PET CT Program, Department of Radiology and Division of Cardiology, Massachusetts General Hospital and Harvard Medical School, 165 Cambridge Street, Boston, MA 02114, USA. amlee@partners.org
authors.forename: Ashley M
authors.initials: AM
authors.lastname: Lee
authors.forename: Leif-Christopher
authors.initials: LC
authors.lastname: Engel
authors.forename: Baiju
authors.initials: B
authors.lastname: Shah
authors.forename: Gary
authors.initials: G
authors.lastname: Liew
authors.forename: Manavjot S
authors.initials: MS
authors.lastname: Sidhu
authors.forename: Mannudeep
authors.initials: M
authors.lastname: Kalra
authors.forename: Suhny
authors.initials: S
authors.lastname: Abbara
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Brady
authors.forename: Udo
authors.initials: U
authors.lastname: Hoffmann
authors.forename: Brian B
authors.initials: BB
authors.lastname: Ghoshhajra
mesh_terms: D001145:Arrhythmias, Cardiac / Q000150:complications* / Q000000981:diagnostic imaging; D055424:Cardiac-Gated Imaging Techniques / Q000379:methods*; D017023:Coronary Angiography / Q000379:methods*; D003324:Coronary Artery Disease / Q000150:complications* / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011829:Radiation Dosage; D011835:Radiation Protection / Q000379:methods; D011856:Radiographic Image Enhancement / Q000379:methods; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D036542:Tomography, Spiral Computed / Q000379:methods*