title: Radiation dose reduction in cardiovascular CT angiography with iterative reconstruction (AIDR 3D) in a swine model: a model of paediatric cardiac imaging.
abstract: OBJECTIVE
  To investigate the potential dose reduction in cardiovascular computed tomography angiography (CTA) in a swine model using 320-detector volume CT with adaptive iterative dose reduction in three dimensions (AIDR 3D) reconstruction to maintain a comparable image quality (IQ) to that reconstructed by a conventional filtered back projection (FBP) algorithm.
  
  
  METHODS
  Twenty-four mini-pigs underwent cardiovascular CTA four times at 80 KVp and different tube currents. An automatic exposure control (AEC) system was used and the noise index (NI) was predetermined at a standard deviation (SD) of 20 (Method A, routine dose), and 25, 30, 35 (Methods B-D) to reduce the dose gradually. Method A was reconstructed with FBP. Methods B-D were reconstructed using AIDR 3D (strong). Two radiologists graded IQ by reviewing both cardiac and vascular structures using a five-point scale. Quantitative IQ parameters of image noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) were measured and compared. A receiver-operating characteristic (ROC) analysis was performed to select a radiation reduction threshold and maintain comparable IQ (score ≥4).
  
  
  RESULTS
  Method B and C had significantly lower image noise (p<0.0001), higher CNR and SNR than Method A (p<0.0001). Compared with Method A (noise: 52.7±8.3; SNR: 11.7±2.8; and CNR: 9.9±2.7), Method C had comparable subjective IQ and higher objective IQ (noise: 38.9±6.1; SNR: 16.3±3.5; and CNR: 13.5±3.3). The results of the ROC curve showed that Method C (SD30) was the optimal dose threshold to maintain a comparable subjective IQ (AUC: 0.85, 95% confidence interval [CI]: 0.80-0.90). The effective dose (ED) of Method C was reduced by 49%, compared to that of Method A (0.33±0.08 mSv versus 0.65±0.15 mSv).
  
  
  CONCLUSIONS
  AIDR 3D at a strong level combined with an AEC system can potentially reduce the ED by 49% and maintain an IQ comparable to that achieved using a routine-dose and FBP reconstruction in mini-pig cardiovascular CTA.
authors.affiliation: Department of Radiology, Shengjing Hospital of China Medical University, 36 Sanhao Street, Shenyang, Liaoning Province 110004, PR China.
authors.forename: Pengfei
authors.initials: P
authors.lastname: Zhao
authors.affiliation: Department of Radiology, Shengjing Hospital of China Medical University, 36 Sanhao Street, Shenyang, Liaoning Province 110004, PR China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Hou
authors.affiliation: Department of Radiology, Shengjing Hospital of China Medical University, 36 Sanhao Street, Shenyang, Liaoning Province 110004, PR China.
authors.forename: Qin
authors.initials: Q
authors.lastname: Liu
authors.affiliation: Department of Radiology, Shengjing Hospital of China Medical University, 36 Sanhao Street, Shenyang, Liaoning Province 110004, PR China.
authors.forename: Yue
authors.initials: Y
authors.lastname: Ma
authors.affiliation: Department of Radiology, Shengjing Hospital of China Medical University, 36 Sanhao Street, Shenyang, Liaoning Province 110004, PR China. Electronic address: guoqy@sj-hospital.org.
authors.forename: Qiyong
authors.initials: Q
authors.lastname: Guo
mesh_terms: D000465:Algorithms; D000818:Animals; D002648:Child; D000072226:Computed Tomography Angiography / Q000379:methods*; D017023:Coronary Angiography / Q000379:methods*; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D010372:Pediatrics / Q000379:methods*; D011829:Radiation Dosage; D011835:Radiation Protection / Q000379:methods*; D011856:Radiographic Image Enhancement / Q000379:methods; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods; D011874:Radiometry; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013552:Swine