Morphological Disease Progression of Combined Pulmonary Fibrosis and Emphysema: Comparison With Emphysema Alone and Pulmonary Fibrosis Alone

Objectives: The purpose of this study was to evaluate the differences in 5-year morphological changes among the patients with combined pulmonary fibrosis and emphysema (CPFE), emphysema alone, and fibrosis alone using quantitative computed tomography evaluation. Methods: This study involved 42 patients with CPFE, 45 patients with emphysema alone, and 35 patients with fibrosis alone who underwent computed tomography scans twice (initial and 5 years after the initial scan). The extent of emphysematous lesions was obtained by calculating the percentage of low attenuation area (% LAA) lower than -950 Hounsfield units. Fibrotic lesion was defined as a high attenuation area (HAA) using thresholds with pixels between 0 and -700 Hounsfield units, and the extent of fibrosis was obtained by calculating the mean percentage of HAA (% HAA). For the quantitative evaluation of the total area of emphysematous change and fibrosis, the percentage of destructed lung area (% DA) was obtained by summing % LAA and % HAA. The 5-year changes of % LAA, % HAA, and % DA were calculated. Differences were evaluated by 1-way analysis of variance, which was followed by the Tukey-Kramer test. Results: The mean change of % LAA was significantly higher in CPFE (7.4% +/- 3.8%) than in emphysema alone (P < 0.05). The mean change of % DA was significantly higher in CPFE (12.9% +/- 5.8%) than in emphysema alone (4.9% +/- 2.8%) and fibrosis alone (7.1% +/- 5.7%). Conclusions: Morphological disease progression in CPFE differed from that in emphysema alone or fibrosis alone. In particular, the increase in emphysematous low-attenuation lesions was significantly higher in CPFE.