Improvement in Ventilation-Perfusion Mismatch after Bronchoscopic Lung Volume Reduction: Quantitative Image Analysis

초록

Purpose: To evaluate whether bronchoscopic lung volume reduction (BLVR) increases ventilation and therefore improves ventilation-perfusion (V/Q) mismatch. Materials and Methods: All patients provided written informed consent to be included in this study, which was approved by the Institutional Review Board (2013-0368) of Asan Medical Center. The physiologic changes that occurred after BLVR were measured by using xenon-enhanced ventilation and iodine enhanced perfusion dual-energy computed tomography (CT). Patients with severe emphysema plus hyperinflation who did not respond to usual treatments were eligible. Pulmonary function tests, the 6-minute walking distance (6MWD) test, quality of life assessment, and dual-energy CT were performed at baseline and 3 months after BLVR. The effect of BLVR was assessed with repeated-measures analysis of variance. Results: Twenty-one patients were enrolled in this study (median age, 68 years; mean forced expiratory volume in 1 second [FEV1]. 0.75 L +/- 0.29). After BLVR, FEV1 (P <.001) and 6MWD (P =.002) improved significantly. Despite the reduction in lung volume (-0.39 L +/- 0.44), both ventilation per voxel (P <.001) and total ventilation (P =.01) improved after BLVR. However, neither perfusion per voxel (P =.16) nor total perfusion changed significantly (P =.49). Patients with lung volume reduction of 50% or greater had significantly better improvement in FEV1 (P =.02) and ventilation per voxel (P =.03) than patients with lung volume reduction of less than 50%. V/Q mismatch also improved after BLVR (P =.005). mainly owing to the improvement in ventilation. Conclusion: The dual-energy CT analyses showed that BLVR improved ventilation and V/Q mismatch. This increased lung efficiency may he the primary mechanism of improvement after BLVR, despite the reduction in lung volume. (C)RSNA, 2017

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