Lung volume reduction surgery has created an opportunity for the advanced imaging of emphysema. Patients with CT or perfusion scintigraphy demonstrating an upper- or lower-lobe-predominant pattern of emphysema have better patient outcomes after LVRS than patients with emphysema diffusely or homogeneously distributed throughout the lungs. Some patients with diffuse or homogeneous emphysema may demonstrate improvement in function or dyspnea after surgery, but the magnitude of the improvement seen is less than in patients with heterogeneous emphysema, and the duration of benefit is not known. An ongoing, multicenter National Heart, Lung, and Blood Institute (NHLBI)/Health Care Financing Association (HCFA) sponsored trial of LVRS aims to determine whether LVRS together with maximal medical therapy and pulmonary rehabilitation improves patient outcomes compared with maximal medical therapy and pulmonary rehabilitation alone. This study will address the duration of clinical benefit and the cost-effectiveness of LVRS.