By Chandra Dass, MBBS, DMRD, Director, Cardiothoracic Imaging, Temple University Hospital
Chronic obstructive pulmonary disease (COPD) is one of the leading causes of mortality and morbidity worldwide. The National Emphysema Treatment Trial (NETT) demonstrated that lung volume reduction surgery can improve pulmonary function, exercise capacity, and quality of life in selected subgroups of COPD patients, yet not all patients are good candidates for surgery. Clinical trials of bronchoscopic lung volume reduction (BLVR) procedures have sought to establish an effective and safe alternative approach for those patients. Of these, endobronchial deployment of one-way valves (EBV) currently has the largest pool of supporting scientific data available.1,2,3
An expert panel, including Temple’s Dr. Gerard Criner, updated the recommendations for patient selection and best practices for endoscopic lungvolume reduction with EBV in 2019. Based on the results of multiple randomized clinical trials (RCTs),3 the panel found that certain image-based COPD patient phenotypes show better outcomes from EBV therapy. High-resolution CT imaging plays a major role in patient selection, target lobe identification, and the management of post-procedural adverse events.
With the recent FDA approval of the Pulmonx Zephyr® and Olympus Spiration® Valve systems, bronchoscopic lung volume reduction using one-way EBVs is increasingly used in patients with advanced emphysema who remain symptomatic despite optimal medical management and are poor surgical candidates. To avoid misinterpretation of imaging studies, it is important for pulmonologists to understand the types of EBV used, and the expected normal imaging findings following placement of EBV. See Figures 1 and 2 for examples.
Given the higher incidence of pneumothorax after EBV placement, chest radiographs are required within 4 and 24 hours of EBV valve placement and daily thereafter until discharge. Significant volume reduction or atelectasis of the treated lobe may be observed within the first few days, although in some patients it may take up to a month. Criteria for premature reevaluation of these patients have been established and imaging plays an important role in their evaluation and management. Expert panels recommend a low-dose CT scan at around 30–45 days post-procedure to assess valve placement, particularly if there is breathing deterioration or no perceived improvement.4 Evaluation of MDCT scans focuses on the valve count, valve location (migration/malpositioning), and target lobe(s) volume change (ΔTLV).
In conclusion, CT and chest radiography are valuable tools for planning and follow-up evaluation of bronchoscopic lung volume reduction treatment for COPD patients. The outcome of EBV therapy is maximized in certain image-based COPD phenotypes. HRCT imaging plays a major role in patient selection, target lobe identification, and in the management of post-procedural adverse events. ■