title: Clinical evaluation and potential radiation dose reduction of the novel sinogram-affirmed iterative reconstruction technique (SAFIRE) in abdominal computed tomography angiography.
abstract: OBJECTIVE
  Computed tomographic angiography is the standard in routine follow-up after endovascular aneurysm repair, causing radiation exposure; thus, dose-saving strategies should be applied. The aim of this study was to evaluate the novel sinogram-affirmed iterative reconstruction (SAFIRE) algorithm in terms of clinical usability and potential reduction of radiation exposure.
  
  
  METHODS
  Forty-six patients underwent computed tomographic angiographic follow-up after endovascular aneurysm repair. Data were acquired using a dual-source computed tomographic scanner running both x-ray tubes at the same voltage (120 kV). Raw data were reconstructed using projections of both tubes with filtered back projection (FBP) and of only one tube with FBP and SAFIRE, corresponding to synthetic acquisition with half the radiation dose of the clinical routine radiation dose. Image sets were objectively compared regarding signal-to-noise ratio and edge sharpness. Two radiologists independently assessed a set of subjective criteria, including diagnostic usability, depiction of contrasted vessels, and image noise.
  
  
  RESULTS
  Half-dose (HD) SAFIRE images showed significantly higher signal-to-noise ratios compared to full-dose FBP images (P < .001), while having equal edge sharpness (P = .56). Most of the subjectively assessed parameters, such as diagnostic usability and depiction of contrasted vessels, were rated similar for HD SAFIRE and full-dose FBP images. Full-dose FBP images depicted fine anatomic structures more clearly (P < .05), while HD SAFIRE data sets showed less noise (P < .01). HD FBP images performed worse on all criteria (P < .001). Interrater agreement was good (κ = 0.74-0.80).
  
  
  CONCLUSIONS
  Using the SAFIRE algorithm, the radiation dose of high-contrast abdominal computed tomographic angiography is reducible from routine clinical levels by up to 50% while maintaining good image quality and diagnostic accuracy.
authors.affiliation: Department of Diagnostic and Interventional Radiology, University Hospital Tübingen, Hoppe-Seyler-Strasse 3, 72076 Tübingen, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Schabel
authors.forename: Michael
authors.initials: M
authors.lastname: Fenchel
authors.forename: Bernhard
authors.initials: B
authors.lastname: Schmidt
authors.forename: Thomas G
authors.initials: TG
authors.lastname: Flohr
authors.forename: Christian
authors.initials: C
authors.lastname: Wuerslin
authors.forename: Christoph
authors.initials: C
authors.lastname: Thomas
authors.forename: Andreas
authors.initials: A
authors.lastname: Korn
authors.forename: Ilias
authors.initials: I
authors.lastname: Tsiflikas
authors.forename: Claus D
authors.initials: CD
authors.lastname: Claussen
authors.forename: Martin
authors.initials: M
authors.lastname: Heuschmid
authors.forename: Dominik
authors.initials: D
authors.lastname: Ketelsen
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D000792:Angiography / Q000379:methods*; D017544:Aortic Aneurysm, Abdominal / Q000000981:diagnostic imaging* / Q000601:surgery*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D011829:Radiation Dosage; D011835:Radiation Protection / Q000379:methods*; D011856:Radiographic Image Enhancement / Q000379:methods; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods; D011860:Radiography, Abdominal / Q000379:methods*; D011874:Radiometry; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*; D016896:Treatment Outcome