title: Iterative image reconstruction techniques: Applications for cardiac CT.
abstract: BACKGROUND
  Traditional limitations of cardiac CT are related to image noise, blooming artifacts from calcifications and stents, and radiation exposure. We evaluated whether these limitations can be ameliorated by the use of iterative reconstruction in image space (IRIS) instead of traditional filtered back projection (FBP) image reconstruction techniques.
  
  
  METHODS
  We compared image reconstruction with the use of IRIS with traditional FBP for their effect on image quality, noise, volume of heavy coronary artery calcifications, and stents as a measure of "blooming" artifacts, and radiation dose at cardiac CT. The radiation dose comparison was performed as a matched pair analysis, whereas all other comparisons were performed within the same group of patients.
  
  
  RESULTS
  The subjective image quality of IRIS reconstructions was rated higher than FBP reconstructions. Image noise was lower with IRIS than with FBP. The volume of stents and heavy coronary artery calcifications measured lower in IRIS reconstructed series compared with FBP. Similar levels of image noise were achieved with 80/100 kVp of tube voltage with IRIS compared with 120 kVp and FBP, resulting in a 62% reduction in effective dose.
  
  
  CONCLUSIONS
  Our preliminary experiences suggest that IRIS incrementally improves the CT evaluation of coronary arteries, especially in challenging scenarios. Substantial radiation reduction seems feasible without associated increases in image noise.
authors: Heart and Vascular Center, Medical University of South Carolina, Ashley River Tower, MSC 226, 25 Courtenay Dr, Charleston, SC 29401, USA.
authors: Matthias
authors: M
authors: Renker
authors: Ashok
authors: A
authors: Ramachandra
authors: U Joseph
authors: UJ
authors: Schoepf
authors: Rainer
authors: R
authors: Raupach
authors: Paul
authors: P
authors: Apfaltrer
authors: Garrett W
authors: GW
authors: Rowe
authors: Sebastian
authors: S
authors: Vogt
authors: Thomas G
authors: TG
authors: Flohr
authors: J Matthias
authors: JM
authors: Kerl
authors: Ralf W
authors: RW
authors: Bauer
authors: Christian
authors: C
authors: Fink
authors: Thomas
authors: T
authors: Henzler
mesh_terms: D000465:Algorithms; D016477:Artifacts; D002114:Calcinosis / Q000000981:diagnostic imaging; D017023:Coronary Angiography / Q000379:methods*; D023921:Coronary Stenosis / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D008297:Male; D016555:Matched-Pair Analysis; D008875:Middle Aged; D011237:Predictive Value of Tests; D011829:Radiation Dosage; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D015607:Stents; D014057:Tomography, X-Ray Computed