title: Improving head and neck CTA with hybrid and model-based iterative reconstruction techniques.
abstract: OBJECTIVE
  To compare image quality of head and neck computed tomography angiography (CTA) reconstructed with filtered back projection (FBP), hybrid iterative reconstruction (HIR) and model-based iterative reconstruction (MIR) algorithms.
  
  
  METHODS
  The raw data of 34 studies were simultaneously reconstructed with FBP, HIR (iDose(4), Philips Healthcare, Best, the Netherlands), and with a prototype version of a MIR algorithm (IMR, Philips Healthcare). Objective (contrast-to-noise ratio [CNR], vascular contrast, automatic vessel analysis [AVA], stenosis grade) and subjective image quality (ranking at level of the circle of Willis, carotid bifurcation, and shoulder) of the five reconstructions were compared using repeated-measures analysis of variance (ANOVA) and post-hoc analysis.
  
  
  RESULTS
  Vascular contrast was significantly higher in both the circle of Willis and carotid bifurcation with both levels of MIR compared to the other reconstruction methods (all p<0.0001). The CNR was highest for high MIR, followed by low MIR, high HIR, mid HIR and FBP (p<0.001 except low MIR versus high HIR; p>0.33). AVA showed most complete carotids in both MIR-levels, followed by high HIR (p>0.08), mid HIR (p<0.023) and FBP (p<0.010), vertebral arteries completeness was similar (p=0.40 and p=0.06). Stenosis grade showed no significant differences (p=0.16). High HIR showed the best subjective image quality at the circle of Willis and carotid bifurcation level, followed by mid HIR. At shoulder level, low MIR and high HIR were ranked best, followed by high MIR.
  
  
  CONCLUSIONS
  Objectively, MIR significantly improved the overall image quality, reduced image noise, and improved automated vessel analysis, whereas FBP showed the lowest objective image quality. Subjectively, the highest level of HIR was considered superior at the level of the circle of Willis and the carotid bifurcation, and along with the lowest level of MIR for the origins of the neck arteries at shoulder level.
authors.affiliation: Department of Radiology, University Medical Center Utrecht, Heidelberglaan, Utrecht, The Netherlands. Electronic address: jmniesten@gmail.com.
authors.forename: J M
authors.initials: JM
authors.lastname: Niesten
authors.affiliation: Department of Radiology, University Medical Center Utrecht, Heidelberglaan, Utrecht, The Netherlands.
authors.forename: I C
authors.initials: IC
authors.lastname: van der Schaaf
authors.affiliation: Department of Radiology, University Medical Center Utrecht, Heidelberglaan, Utrecht, The Netherlands.
authors.forename: P C
authors.initials: PC
authors.lastname: Vos
authors.affiliation: Department of Radiology, University Medical Center Utrecht, Heidelberglaan, Utrecht, The Netherlands.
authors.forename: M J
authors.initials: MJ
authors.lastname: Willemink
authors.affiliation: Department of Radiology, University Medical Center Utrecht, Heidelberglaan, Utrecht, The Netherlands.
authors.forename: B K
authors.initials: BK
authors.lastname: Velthuis
mesh_terms: D000465:Algorithms; D000704:Analysis of Variance; D000792:Angiography / Q000379:methods / Q000592:standards; D002545:Brain Ischemia / Q000000981:diagnostic imaging; D002339:Carotid Arteries / Q000000981:diagnostic imaging*; D002941:Circle of Willis / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods* / Q000592:standards; D002532:Intracranial Aneurysm / Q000000981:diagnostic imaging; D002538:Intracranial Arteriovenous Malformations / Q000000981:diagnostic imaging; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D011446:Prospective Studies; D058996:Quality Improvement; D012851:Sinus Thrombosis, Intracranial / Q000000981:diagnostic imaging; D014057:Tomography, X-Ray Computed / Q000379:methods / Q000592:standards