title: Impact of iterative reconstructions on objective and subjective emphysema assessment with computed tomography: a prospective study.
abstract: OBJECTIVE
  To prospectively evaluate the impact of iterative reconstruction (IR) algorithms on pulmonary emphysema assessment as compared to filtered back projection (FBP).
  
  
  METHODS
  One hundred ten unenhanced chest CT examinations were obtained on two different scanners. Image reconstructions from a single acquisition were done with different levels of IR and compared with FBP on the basis of the emphysema index (EI), lung volume and voxel densities. Objective emphysema assessment was performed with 3D software provided by each manufacturer. Subjective assessment of emphysema was performed as a blinded evaluation. Quantitative and subjective values were compared using repeated ANOVA analysis, Bland-Altman analysis and Kendall's coefficient of concordance (W).
  
  
  RESULTS
  Lung volumes are stable on both units, throughout all IR levels (P ≥ 0.057). EI significantly decreases on both units with the use of any level of IR (P < 0.001). The highest levels of IR are responsible for a decrease of 33-36 % of EI. Significant differences in minimal lung density are found between the different algorithms (P < 0.003). Intra- and inter-reader concordance for emphysema characterisation is generally good (W ≥ 0.77 and W ≥ 0.86, respectively).
  
  
  CONCLUSIONS
  Both commercially available IR algorithms used in this study significantly changed EI but did not alter visual assessment compared to standard FBP reconstruction at identical radiation exposure.
  
  
  CONCLUSIONS
  • Objective quantification of pulmonary emphysema is sensitive to iterative reconstructions • Subjective evaluation of pulmonary emphysema is not influenced by iterative reconstructions • Consistency in reconstruction algorithms is of paramount importance for pulmonary emphysema monitoring.
authors.affiliation: Division of Radiology, Department of Imaging and Medical Information Sciences, Geneva University Hospitals, Geneva, Switzerland. Steve.Martin@hcuge.ch.
authors.forename: Steve P
authors.initials: SP
authors.lastname: Martin
authors.affiliation: Division of Radiology, Department of Imaging and Medical Information Sciences, Geneva University Hospitals, Geneva, Switzerland.
authors.forename: Joanna
authors.initials: J
authors.lastname: Gariani
authors.affiliation: Division of Radiology, Department of Imaging and Medical Information Sciences, Geneva University Hospitals, Geneva, Switzerland.
authors.forename: Anne-Lise
authors.initials: AL
authors.lastname: Hachulla
authors.affiliation: Division of Radiology, Department of Imaging and Medical Information Sciences, Geneva University Hospitals, Geneva, Switzerland.
authors.forename: Diomidis
authors.initials: D
authors.lastname: Botsikas
authors.affiliation: Division of Pneumology, Department of Internal Medicine, Geneva University Hospitals, Geneva, Switzerland.
authors.forename: Dan
authors.initials: D
authors.lastname: Adler
authors.affiliation: Division of Thoracic Surgery, Department of Surgery, Geneva University Hospitals, Geneva, Switzerland.
authors.forename: Wolfram
authors.initials: W
authors.lastname: Karenovics
authors.affiliation: Division of Radiology, Department of Imaging and Medical Information Sciences, Geneva University Hospitals, Geneva, Switzerland.
authors.forename: Christoph D
authors.initials: CD
authors.lastname: Becker
authors.affiliation: Division of Radiology, Department of Imaging and Medical Information Sciences, Geneva University Hospitals, Geneva, Switzerland.
authors.forename: Xavier
authors.initials: X
authors.lastname: Montet
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011656:Pulmonary Emphysema / Q000000981:diagnostic imaging*; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D012984:Software; D014057:Tomography, X-Ray Computed / Q000379:methods*
keywords: Iterative reconstruction; Multidetector computed tomography; Pulmonary emphysema; Quantitative analysis; Visual assessment