Clinical and quantitative computed tomography predictors of response to endobronchial lung volume reduction therapy using coils

Abstract

Objectives: Bronchoscopic lung volume reduction using coils (LVRC) is a well-known treatment option for severe emphysema. The purpose of this study was to identify quantitative computed tomography (QCT) and clinical parameters associated with positive treatment outcome. Patients and methods: The CT scans, pulmonary function tests (PFT), and 6-minute walk test (6-MWT) data were collected from 72 patients with advanced emphysema prior to and at 3 months after LVRC treatment. The procedure involved placing 10 coils unilaterally. Various QCT parameters were derived using Apollo imaging software (VIDA). Independent predictors of clinically relevant outcome (∆6-MWT ≥ 26 m, ∆FEV1 ≥ 12%, ∆RV ≥ 10%) were identified through stepwise linear regression analysis. Results: The response outcome for ∆6-MWT, for ∆FEV1 and for ∆RV was met by 55%, 32% and 42%, respectively. For ∆6-MWT ≥ 26 m a lower baseline 6-MWT (p = 0.0003) and a larger standard deviation (SD) of low attenuation cluster (LAC) sizes in peripheral regions of treated lung (p = 0.0037) were significantly associated with positive outcome. For ∆FEV1 ≥ 12%, lower baseline FEV1 (p = 0.02) and larger median LAC sizes in the central regions of treated lobe (p = 0.0018) were significant predictors of good response. For ∆RV ≥ 10% a greater baseline TLC (p = 0.0014) and a larger SD of LAC sizes in peripheral regions of treated lung (p = 0.007) tended to respond better. Conclusion: Patients with lower FEV1 and 6-MWT, with higher TLC and specific QCT characteristics responded more positively to LVRC treatment, suggesting a more targeted CT-based approach to patient selection could lead to greater efficacy in treatment response.