title: Cardiac CT for planning redo cardiac surgery: effect of knowledge-based iterative model reconstruction on image quality.
abstract: OBJECTIVE
  The purpose of this study was to investigate the effects of knowledge-based iterative model reconstruction (IMR) on image quality in cardiac CT performed for the planning of redo cardiac surgery by comparing IMR images with images reconstructed with filtered back-projection (FBP) and hybrid iterative reconstruction (HIR).
  
  
  METHODS
  We studied 31 patients (23 men, 8 women; mean age 65.1 ± 16.5 years) referred for redo cardiac surgery who underwent cardiac CT. Paired image sets were created using three types of reconstruction: FBP, HIR, and IMR. Quantitative parameters including CT attenuation, image noise, and contrast-to-noise ratio (CNR) of each cardiovascular structure were calculated. The visual image quality--graininess, streak artefact, margin sharpness of each cardiovascular structure, and overall image quality--was scored on a five-point scale.
  
  
  RESULTS
  The mean image noise of FBP, HIR, and IMR images was 58.3 ± 26.7, 36.0 ± 12.5, and 14.2 ± 5.5 HU, respectively; there were significant differences in all comparison combinations among the three methods. The CNR of IMR images was better than that of FBP and HIR images in all evaluated structures. The visual scores were significantly higher for IMR than for the other images in all evaluated parameters.
  
  
  CONCLUSIONS
  IMR can provide significantly improved qualitative and quantitative image quality at in cardiac CT for planning of reoperative cardiac surgery.
  
  
  CONCLUSIONS
  • Cardiac CT before redo surgery may mitigate increased risk • Iterative model reconstruction is the next generation in iterative reconstruction • Iterative model reconstruction improves the image quality in cardiac CT.
authors.affiliation: Department of Cardiology, MedStar Washington Hospital Center, 110 Irving Street, NW, Suite 4B-1, Washington, DC, 20010, USA, seisei0430@nifty.com.
authors.forename: Seitaro
authors.initials: S
authors.lastname: Oda
authors.forename: Gaby
authors.initials: G
authors.lastname: Weissman
authors.forename: Mani
authors.initials: M
authors.lastname: Vembar
authors.forename: Wm Guy
authors.initials: WG
authors.lastname: Weigold
mesh_terms: D000368:Aged; D000465:Algorithms; D006348:Cardiac Surgical Procedures; D017023:Coronary Angiography / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D057234:Preoperative Period; D011829:Radiation Dosage; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed / Q000379:methods*