title: Comparison of image quality and radiation dose between prospectively ECG-triggered and retrospectively ECG-gated CT angiography: Establishing heart rate cut-off values in first-generation dual-source CT.
abstract: OBJECTIVE
  To evaluate radiation dose and image quality of prospectively electrocardiography (ECG)-triggered and retrospectively ECG-gated coronary computed tomography (CT) angiography and to establish cut-off values of heart rates (HRs) for each technique in first-generation dual-source CT.
  
  
  METHODS
  A total of 200 consecutive patients with suspected coronary artery disease were accepted into the study. Patients were selected randomly for each technique (prospective triggering group n=99, mean age 55.85±10.74 and retrospective gating group n=101, mean age 53.38±11.58). Two independent radiologists scored coronary artery segments for image quality using a 5-point scale. Also, attenuation values of each coronary artery segment and dose-length product values were measured. For each technique, cut-off HR values were determined for the best image quality.
  
  
  RESULTS
  Mean image quality scores and attenuation values were found to be higher in the prospective triggering group (p<0.05). Mean radiation dose was 73% lower for the prospective triggering group (p<0.01). The cut-off HR values for good image quality scores were ≤67 beats per minute (bpm) and ≤80 bpm for the prospective triggering and retrospective gating groups, respectively (p<0.05). Increased HR (≥68 and ≥81 bpm, respectively) had negative effects on image quality (p<0.05).
  
  
  CONCLUSIONS
  The prospective ECG triggering technique has better image quality scores than retrospective ECG gating, particularly in patients who have an HR of less than 68 bpm. Also, a 73% radiation dose reduction can be achieved with prospective ECG triggering. In patients with higher heart rates, retrospective ECG gating is recommended.
authors.affiliation: Department of Radiology, Faculty of Medicine, Hacettepe University; Ankara-Turkey. tuncayhazirolan@yahoo.com.
authors.forename: Emre
authors.initials: E
authors.lastname: Ünal
authors.forename: A Elçin
authors.initials: AE
authors.lastname: Yıldız
authors.forename: Ezgi
authors.initials: E
authors.lastname: Güler
authors.forename: Muşturay
authors.initials: M
authors.lastname: Karcaaltıncaba
authors.forename: Deniz
authors.initials: D
authors.lastname: Akata
authors.forename: Abidin
authors.initials: A
authors.lastname: Kılınçer
authors.forename: Eray
authors.initials: E
authors.lastname: Atlı
authors.forename: Melih
authors.initials: M
authors.lastname: Topçuoğlu
authors.forename: Tuncay
authors.initials: T
authors.lastname: Hazırolan
mesh_terms: D055424:Cardiac-Gated Imaging Techniques / Q000379:methods; D017023:Coronary Angiography / Q000379:methods; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging* / Q000503:physiopathology; D004562:Electrocardiography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods; D015203:Reproducibility of Results; D012189:Retrospective Studies