title: Influence of adaptive statistical iterative reconstruction algorithm on image quality in coronary computed tomography angiography.
abstract: BACKGROUND
  Coronary computed tomography angiography (CCTA) requires high spatial and temporal resolution, increased low contrast resolution for the assessment of coronary artery stenosis, plaque detection, and/or non-coronary pathology. Therefore, new reconstruction algorithms, particularly iterative reconstruction (IR) techniques, have been developed in an attempt to improve image quality with no cost in radiation exposure.
  
  
  OBJECTIVE
  To evaluate whether adaptive statistical iterative reconstruction (ASIR) enhances perceived image quality in CCTA compared to filtered back projection (FBP).
  
  
  METHODS
  Thirty patients underwent CCTA due to suspected coronary artery disease. Images were reconstructed using FBP, 30% ASIR, and 60% ASIR. Ninety image sets were evaluated by five observers using the subjective visual grading analysis (VGA) and assessed by proportional odds modeling. Objective quality assessment (contrast, noise, and the contrast-to-noise ratio [CNR]) was analyzed with linear mixed effects modeling on log-transformed data. The need for ethical approval was waived by the local ethics committee as the study only involved anonymously collected clinical data.
  
  
  RESULTS
  VGA showed significant improvements in sharpness by comparing FBP with ASIR, resulting in odds ratios of 1.54 for 30% ASIR and 1.89 for 60% ASIR (P= 0.004). The objective measures showed significant differences between FBP and 60% ASIR (P< 0.0001) for noise, with an estimated ratio of 0.82, and for CNR, with an estimated ratio of 1.26.
  
  
  CONCLUSIONS
  ASIR improved the subjective image quality of parameter sharpness and, objectively, reduced noise and increased CNR.
authors.affiliation: Department of Medical Research, Odense University Hospital Svendborg, Svendborg, Denmark; Conrad Research Programme, University College Lillebelt, Odense, Denmark.
authors.forename: Helle
authors.initials: H
authors.lastname: Precht
authors.affiliation: Department of Clinical Engineering, Central Denmark Region, Århus, Denmark.
authors.forename: Jesper
authors.initials: J
authors.lastname: Thygesen
authors.affiliation: Department of Nuclear Medicine, Odense University Hospital, Odense, Denmark; Center of Health Economics Research, University of Southern Denmark, Odense, Denmark.
authors.forename: Oke
authors.initials: O
authors.lastname: Gerke
authors.affiliation: Department of Medical Research, Odense University Hospital Svendborg, Svendborg, Denmark.
authors.forename: Kenneth
authors.initials: K
authors.lastname: Egstrup
authors.affiliation: Gjøvik University College, Gjøvik, Norway.
authors.forename: Dag
authors.initials: D
authors.lastname: Waaler
authors.affiliation: Department of Medical Research, Odense University Hospital Svendborg, Svendborg, Denmark.
authors.forename: Jess
authors.initials: J
authors.lastname: Lambrechtsen
keywords: Computed tomography angiography (CTA); cardiac; image manipulation/reconstruction; perception image; vascular