Impact of iterative reconstructions on objective and subjective emphysema assessment with computed tomography: a prospective study
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To prospectively evaluate the impact of iterative reconstruction (IR) algorithms on pulmonary emphysema assessment as compared to filtered back projection (FBP).
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).
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).
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.
• 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
KeywordsPulmonary emphysema Multidetector computed tomography Iterative reconstruction Quantitative analysis Visual assessment
Abbreviations and acronyms
Adaptive statistical image reconstruction
Filtered back projection
Low attenuation value percentage
Sinogram affirmed iterative reconstruction
Model-based iterative reconstruction
The scientific guarantor of this publication is PR Xavier Montet. The authors of this manuscript declare no relationships with any companies, whose products or services may be related to the subject matter of the article. The authors state that this work has not received any funding.
No complex statistical methods were necessary for this paper. Institutional Review Board approval was obtained. Written informed consent was obtained from all subjects (patients) in this study. Methodology: prospective, case-control study, performed at one institution.
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