title: Double prospectively ECG-triggered high-pitch spiral acquisition for CT coronary angiography: initial experience.
abstract: OBJECTIVE
  To evaluate the feasibility of double prospectively electrocardiogram (ECG)-triggered high-pitch spiral acquisition mode (double high-pitch mode) for coronary computed tomography angiography (CTCA).
  
  
  METHODS
  One hundred and forty-nine consecutive patients [40 women, 109 men; mean age 58.2 ± 9.2 years; sinus rhythm ≤70 beats/min (bpm) after pre-medication, body weight ≤100 kg] were enrolled for CTCA examinations using a dual-source CT system with 2 × 128 × 0.6 mm collimation, 0.28 s rotation time, and a pitch of 3.4. Double high-pitch mode was prospectively triggered first at 60% and later at 30% of the R-R interval within two cardiac cycles. Image quality was evaluated using a four-point scale (1 = excellent, 4 = non-assessable).
  
  
  RESULTS
  From 2085 coronary artery segments, 86.4% (1802/2085) were rated as having a score of 1, 12.3% (257/2085) as score of 2, 1.2% (26/2085) as score of 3, and none were rated as "non-assessable". The average image quality score was 1.15 ± 0.26 on a per-segment basis. The effective dose was calculated by multiplying the coefficient factor of 0.028 by the dose-length product (DLP); the mean effective dose was 3.5 ± 0.8 mSv (range 1.7-7.6 mSv). The total dosage of contrast medium was 78.7 ± 2.9 ml.
  
  
  CONCLUSIONS
  Double prospectively ECG-triggered high-pitch spiral acquisition mode provides good image quality with an average effective dose of less than 5 mSv in patients with a heart rate ≤70 bpm.
authors.affiliation: Department of Cardiology, Chinese PLA General Hospital, Beijing, China.
authors.forename: Q
authors.initials: Q
authors.lastname: Wang
authors.forename: J
authors.initials: J
authors.lastname: Qin
authors.forename: B
authors.initials: B
authors.lastname: He
authors.forename: Y
authors.initials: Y
authors.lastname: Zhou
authors.forename: J-J
authors.initials: JJ
authors.lastname: Yang
authors.forename: X-L
authors.initials: XL
authors.lastname: Hou
authors.forename: X-B
authors.initials: XB
authors.lastname: Yang
authors.forename: J-H
authors.initials: JH
authors.lastname: Chen
authors.forename: Y-D
authors.initials: YD
authors.lastname: Chen
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D055424:Cardiac-Gated Imaging Techniques / Q000379:methods*; D003287:Contrast Media; D017023:Coronary Angiography / Q000379:methods*; D023921:Coronary Stenosis / Q000000981:diagnostic imaging*; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011829:Radiation Dosage; D011857:Radiographic Image Interpretation, Computer-Assisted; D018709:Statistics, Nonparametric; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media