title: Prospective ECG-triggered coronary CT angiography: clinical value of noise-based tube current reduction method with iterative reconstruction.
abstract: OBJECTIVE
  To evaluate the clinical value of noise-based tube current reduction method with iterative reconstruction for obtaining consistent image quality with dose optimization in prospective electrocardiogram (ECG)-triggered coronary CT angiography (CCTA).
  
  
  METHODS
  We performed a prospective randomized study evaluating 338 patients undergoing CCTA with prospective ECG-triggering. Patients were randomly assigned to fixed tube current with filtered back projection (Group 1, n = 113), noise-based tube current with filtered back projection (Group 2, n = 109) or with iterative reconstruction (Group 3, n = 116). Tube voltage was fixed at 120 kV. Qualitative image quality was rated on a 5-point scale (1 = impaired, to 5 = excellent, with 3-5 defined as diagnostic). Image noise and signal intensity were measured; signal-to-noise ratio was calculated; radiation dose parameters were recorded. Statistical analyses included one-way analysis of variance, chi-square test, Kruskal-Wallis test and multivariable linear regression.
  
  
  RESULTS
  Image noise was maintained at the target value of 35HU with small interquartile range for Group 2 (35.00-35.03HU) and Group 3 (34.99-35.02HU), while from 28.73 to 37.87HU for Group 1. All images in the three groups were acceptable for diagnosis. A relative 20% and 51% reduction in effective dose for Group 2 (2.9 mSv) and Group 3 (1.8 mSv) were achieved compared with Group 1 (3.7 mSv). After adjustment for scan characteristics, iterative reconstruction was associated with 26% reduction in effective dose.
  
  
  CONCLUSIONS
  Noise-based tube current reduction method with iterative reconstruction maintains image noise precisely at the desired level and achieves consistent image quality. Meanwhile, effective dose can be reduced by more than 50%.
authors.affiliation: Department of Radiology, Xuanwu Hospital of Capital Medical University, Beijing, China.
authors.forename: Junlin
authors.initials: J
authors.lastname: Shen
authors.forename: Xiangying
authors.initials: X
authors.lastname: Du
authors.forename: Daode
authors.initials: D
authors.lastname: Guo
authors.forename: Lizhen
authors.initials: L
authors.lastname: Cao
authors.forename: Yan
authors.initials: Y
authors.lastname: Gao
authors.forename: Qi
authors.initials: Q
authors.lastname: Yang
authors.forename: Pengyu
authors.initials: P
authors.lastname: Li
authors.forename: Jiabin
authors.initials: J
authors.lastname: Liu
authors.forename: Kuncheng
authors.initials: K
authors.lastname: Li
mesh_terms: D000368:Aged; D017023:Coronary Angiography / Q000379:methods*; D004562:Electrocardiography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011829:Radiation Dosage; D011856:Radiographic Image Enhancement; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods; D059629:Signal-To-Noise Ratio; D014057:Tomography, X-Ray Computed / Q000379:methods*