Prediction of response to endobronchial coiling based on morphologic emphysema characterization of the lung lobe to be treated and the ipsilateral non-treated lobe as well as on functional computed tomography-data: correlation with clinical and pulmonary function

Abstract

Background: To test if the emphysema type of the targeted lobe, ipsilateral non-targeted lobe, and lobes of the contralateral lung impact outcome of endobronchial lung volume reduction (ELVR) treatment, and to document lobar volume changes in treated and non-treated lung lobes. Methods: Thirty patients (16 men, 14 women; median age, 66±6 years; range, 48-78 years) underwent chest-computed tomography (CT) before and after endobronchial coiling for lung volume reduction (LVR) at our institution between December 2011 and March 2016. Forty-five pulmonary lobes were coiled.We classified the treated lobes into homogenous or heterogeneous emphysema phenotype based on the distribution of voxels showing tissue attenuation of less than −950 HU. Clinical response was defined as an increase or consistency in the walking distance (6MWT) 6 months after LVR-therapy. Lung volume changes were compared for treated, ipsilateral, and contralateral lobes. Additionally, pulmonary function tests (PFT), chronic obstructive pulmonary disease (COPD) assessment test (CAT), and blood gas analysis were performed. Results: Responder (19/30, 63.3%) showed a significant improvement of 6 MWT from 281.05 to 335.26 (P=0.001). Non-responder (11/30, 36.7%) showed a decrease in 6MWT from 308.18 to 255.45 (P=0.001).Responders showed a significant reduction in CAT test from 23.23 to 20.73 points (P=0.038) and pCO 2 from 42.94 to 40.31 (P=0.001), whereas non-responders showed an increase in pCO 2 (P=0.003; from 44.27 to 47.45). There were no significant changes in PFT-parameters. In responders, there was a significant volume reduction in treated lobes from 1,627.68 to 1,519.21 mL (P=0.009). In responders, treated lobes/non-treated ipsilateral lobes were homogenous (n=11/5) and heterogeneous (n=10/28). In non-responders, treated lobes/non-treated ipsilateral were homogenous (n=5/4) and heterogeneous (n=7/16). In responders and non-responders, the emphysema phenotype in treated, ipsilateral non-treated and even contralateral lobes (P=0.250) did not differ and or change significantly before and after therapy. Only the volume of treated lobes in responders changed significantly after coiling.

Bullous Parametric Response Map for Functional Localization of COPD

“…The current target lobe selection in BLVR is based on densitometric data on inspiratory CT scans. In the work of Kloth et al [25,26], the cluster analysis of LACs representing connected voxels of HU values under -950 was conducted using Pulmo 3D software (Siemens Healthcare). Unlike the fraction of density integrated into this study, Kloth et al categorized the LACs of inspiratory CT in four empirical volume clusters to visually differentiate the homogeneous and heterogeneous of the emphysema phenotypes.…”

“…The fourth row is the result of second-row using low attenuation clusters. Fifth row: left is the visualization result of PRM in a three-dimensional model, the center is the mapping of the PRM on HU values of inspiratory CT, right is the result of regional functional prediction mark on the grids, which has blue color as the most severe candidates for the target lobes the outcome [26]. However, it has to be considered that determining the emphysema heterogeneity in our study is more than qualitative analysis.…”