title: Improved image-quality consistency in coronary CT angiography using a test-bolus-based individually tailored contrast medium injection protocol.
abstract: OBJECTIVE
  To develop and validate a test bolus (TB)-based quantitative model to create an individualised contrast medium injection protocol for use at coronary computed tomography angiography (CCTA) to improve patient-to-patient uniformity of intracoronary attenuation.
  
  
  METHODS
  In the model-building phase, 175 patients who underwent CCTA using a traditional contrast medium injection protocol were recruited. A personalised injection equation was proposed according to the relationship between aortic enhancement and the haemodynamic parameters obtained from the TB. In the model-validation phase, a target aortic enhancement of 350 HU was set. Two hundred and fifteen additional CCTA examinations were performed using the proposed personalised injection model. Comparisons of inter-individual variability between the traditional and the proposed personalised injection protocol were performed.
  
  
  RESULTS
  In the model-building phase, a high positive correlation between aortic enhancement and the haemodynamic parameters obtained from the TB was found. As a result, a personalised injection equation was determined using linear regression. In the model-validation phase, the average aortic enhancement was 350.5 HU, without significant differences from the preset level. Using the TB-based personalised injection protocol, inter-individual variability of aortic enhancement was significantly reduced (71.8 versus 38.9 HU, p<0.001) and patients who were scanned at 100 kVp had a reduction in the average contrast medium flow rate from 4.1 to 3.2 ml/s (p<0.001).
  
  
  CONCLUSIONS
  The proposed TB-based injection protocol can achieve a desired preset and stable aortic enhancement.
authors.affiliation: Department of Radiology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, 210029, China.
authors.forename: X
authors.initials: X
authors.lastname: Zhu
authors.affiliation: Department of Radiology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, 210029, China.
authors.forename: Y
authors.initials: Y
authors.lastname: Zhu
authors.affiliation: Department of Radiology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, 210029, China.
authors.forename: W
authors.initials: W
authors.lastname: Liu
authors.affiliation: Lab. of Image Science & Technology, School of Computer Science and Engineering, Southeast University, 2 Sipailou, Nanjing 210096, Jiangsu, China.
authors.forename: G
authors.initials: G
authors.lastname: Yang
authors.affiliation: GE Healthcare, 12f Building A, E-town International Center, No. 10 Ronghua Road, Business Development Area, Beijing, 100176, China.
authors.forename: Z
authors.initials: Z
authors.lastname: Su
authors.affiliation: Department of Radiology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, 210029, China. Electronic address: Lijun.tang@hotmail.com.
authors.forename: L
authors.initials: L
authors.lastname: Tang
authors.affiliation: Department of Radiology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, 210029, China. Electronic address: aleenxu@hotmail.com.
authors.forename: Y
authors.initials: Y
authors.lastname: Xu
mesh_terms: D001011:Aorta / Q000000981:diagnostic imaging; D000072226:Computed Tomography Angiography / Q000379:methods*; D003287:Contrast Media / Q000008:administration & dosage*; D017023:Coronary Angiography / Q000379:methods*; D005260:Female; D006801:Humans; D007275:Injections, Intravenous; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011856:Radiographic Image Enhancement / Q000379:methods*; D015203:Reproducibility of Results
chemical_list: D003287:Contrast Media