In this study, we made three observations regarding the use of IR for CT-based quantitative analysis of emphysema.
1) The extent of emphysema was more consistent across three different tube currents on CT images when using AIDR3D than on CT images when using FBP. 2) Similar to previous studies that used different IR techniques,5–9 using AIDR3D resulted in slightly higher MLD, smaller LAA%, and higher 15th percentile values than when using conventional FBP. 3) Measurement errors for LAA% or 15th percentiles were correlated with patients’ body weights on scans without AIDR3D, and were minimized on scans with AIDR3D. Based on these observations, we believe that using IR should be recommended for quantitative analysis of emphysema to reduce measurement errors that are caused by tube current settings and body habitus; however, investigators must be aware that there will inevitably be differences in measured values between scans using IR and those using FBP.