title: CT coronary angiography: image quality with sinogram-affirmed iterative reconstruction compared with filtered back-projection.
abstract: OBJECTIVE
  To investigate image quality and potential for radiation dose reduction using sinogram-affirmed iterative reconstruction (SAFIRE) at computed tomography (CT) coronary angiography (CTCA) compared with filtered back-projection (FBP) reconstruction.
  
  
  METHODS
  A water phantom and 49 consecutive patients were scanned using a retrospectively electrocardiography (ECG)-gated CTCA protocol on a dual-source CT system. Image reconstructions were performed with both conventional FBP and SAFIRE. The SAFIRE series were reconstructed image data from only one tube, simulating a 50% radiation dose reduction. Two blinded observers independently assessed the image quality of each coronary segment using a four-point scale and measured image noise (the standard deviation of Hounsfield values, SD), signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR). Radiation dose estimates were calculated.
  
  
  RESULTS
  In the water phantom, image noise decreased at the same ratio as the tube current increased for both reconstruction algorithms. Despite an estimated radiation dose reduction from 7.9 ± 2.8 to 4 ± 1.4 mSv, there was no significant difference in the SD and SNR within the aortic root and left ventricular chamber between the two reconstruction methods. There was also no significant difference in the image quality between the FBP and SAFIRE series.
  
  
  CONCLUSIONS
  Compared with traditional FBP, there is potential for substantial radiation dose reduction at CTCA with use of SAFIRE, while maintaining similar diagnostic image quality.
authors.affiliation: Department of Radiology, Beijing Anzhen Hospital, Capital Medical University, Beijing, China.
authors.forename: R
authors.initials: R
authors.lastname: Wang
authors.forename: U J
authors.initials: UJ
authors.lastname: Schoepf
authors.forename: R
authors.initials: R
authors.lastname: Wu
authors.forename: K P
authors.initials: KP
authors.lastname: Gibbs
authors.forename: W
authors.initials: W
authors.lastname: Yu
authors.forename: M
authors.initials: M
authors.lastname: Li
authors.forename: Z
authors.initials: Z
authors.lastname: Zhang
mesh_terms: D000465:Algorithms; D000704:Analysis of Variance; D055424:Cardiac-Gated Imaging Techniques; D016009:Chi-Square Distribution; D003287:Contrast Media; D017023:Coronary Angiography / Q000379:methods*; D003327:Coronary Disease / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D007472:Iohexol / Q000031:analogs & derivatives; D008297:Male; D008875:Middle Aged; D019047:Phantoms, Imaging; D011829:Radiation Dosage; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media; D007472:Iohexol; C038192:iopromide