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

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. 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. 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 pCO2 from 42.94 to 40.31 (P=0.001), whereas non-responders showed an increase in pCO2 (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. The emphysema-phenotype in the targeted and non-targeted ipsilateral lobe has no impact on the outcome of endobronchial coiling for LVR and also does not change significantly after treatment, whereas the volume of the treated lobe significantly decreases in responders.