The Percentage of Low Attenuation Area on Computed Tomography to Detect Chronic Lung Allograft Dysfunction After Bilateral Lung Transplantation

Abstract

<h3>Purpose</h3> Lung emphysematous changes may develop in patients with chronic lung allograft dysfunction (CLAD) after lung transplantation (LT). To evaluate the severity of lung emphysema, the percentage of low attenuation area (LAA%) of the bilateral lungs calculated on computed tomography has been shown to be a useful index. This study aimed to investigate whether the LAA% was associated with the development of CLAD after bilateral LT. <h3>Methods</h3> We conducted a single-center retrospective study of 75 recipients who underwent bilateral LT from May 2008 to August 2015. The LAA% on computed tomography were calculated and compared between the CLAD group (N = 30) and the non-CLAD group (N = 45) from 2 years before to 4 years after the diagnosis of CLAD. The LAA% at 5 years after bilateral LT was designated as the control value in the non-CLAD group. The Pearson product-moment correlation coefficient was calculated between the LAA% and the percent baseline values of the forced expiratory volume in 1 s (FEV1), the forced vital capacity (FVC), and the total lung capacity (TLC) at the diagnosis of CLAD after bilateral LT. <h3>Results</h3> The median observation period after LT was 3277 (380-7691) days. The LAA% in the CLAD group was significantly higher than that in the non-CLAD group from even 2 years before the diagnosis of CLAD to 2 years after the diagnosis of CLAD (P < 0.05) (Figure 1). The difference in the LAA% between the CLAD group and the non-CLAD group tended to increase after the onset of CLAD. Furthermore, the LAA% was significantly correlated with the percent baseline values of the FEV1, the FVC, and the TLC (FEV1, r = -0.36, P = 0.0031; FVC, r = -0.27, P = 0.027; TLC, r = -0.40, P < 0.001) (Figure 2). <h3>Conclusion</h3> The LAA% was associated with the development of CLAD and increased after the diagnosis of CLAD. Moreover, the LAA% was associated with declines in the FEV1, FVC and TLC at the time of CLAD diagnosis. The LAA% appears to have the potential to predict CLAD after bilateral LT.