Comparison of the effects of model-based iterative reconstruction and filtered back projection algorithms on software measurements in pulmonary subsolid nodules

To evaluate the differences between filtered back projection (FBP) and model-based iterative reconstruction (MBIR) algorithms on semi-automatic measurements in subsolid nodules (SSNs). Unenhanced CT scans of 73 SSNs obtained using the same protocol and reconstructed with both FBP and MBIR algorithms were evaluated by two radiologists. Diameter, mean attenuation, mass and volume of whole nodules and their solid components were measured. Intra- and interobserver variability and differences between FBP and MBIR were then evaluated using Bland-Altman method and Wilcoxon tests. Longest diameter, volume and mass of nodules and those of their solid components were significantly higher using MBIR (p??0.05). Semi-automatic measurements of SSNs significantly differed between FBP and MBIR; however, the differences were within the range of measurement variability. ? Intra- and interobserver reproducibility of measurements did not differ between FBP and MBIR. ? Differences in SSNs' semi-automatic measurement induced by reconstruction algorithms were not clinically significant. ? Semi-automatic measurement may be conducted regardless of reconstruction algorithm. ? SSNs' semi-automated classification agreement (pure vs. part-solid) did not significantly differ between algorithms.