Emphysema is a leading cause of disability and death in the United States and worldwide. Millions of people suffer from this disease, which often goes undiagnosed for many years and irreversibly destroys lung parenchyma. It is unclear how the disease progresses, but there are emerging investigations indicating that the development and extent of emphysema may follow certain pathogenic pathways. In recent years, bronchoscopic lung volume reduction therapy has been gaining significant attention as a treatment for emphysema to reduce hyperinflation, improve lung function, and relieve symptoms (e.g., short of breath) because of its minimally invasive characteristic. However, it is difficult to determine which patients could actually benefit from this bronchoscopic therapy. The primary challenge is the lack of an accurate, quantitative, and non-invasive way to assess an individual's inter-lobar collateral ventilation (CV). Preliminarily studies by some investigators and us revealed that pulmonary fissure integrity (completeness) depicted on CT images may play a crucial role in interlobar CV, but the exact contribution to the interlobar CV remains unclear. We propose to advance our previous work to comprehensively investigate pulmonary fissure morphology, emphysema distribution patterns, and their 3D spatial integration. Our ultimate goal is to develop a risk stratification model for assessing function decline, COPD progression, and responses to endobronchial valve (EBV) therapy. Our assumption is that the interlobar CV is affected by multiple factors, such as the existence of incomplete fissures surrounded by emphysema, and not simply fissure integrity. Therefore the current approaches to assess interlobar CV by fissure integrity on CT images may be insufficient. If successful, the developed computer tool may not only aid in assessing COPD progression and possible developing optimal patient management practices, but also significantly simplify pre-operative work-up in identifying patients for EBV therapy. We have the following specific aims: (1) continue to populate our chest CT examination database, (2) further develop our 3D fissure and lung models to integrates fissure morphology and emphysema severity and distribution, (3) evaluate the functional implications of features morphology, emphysema distribution patterns, and integrative lung model, and (4) develop and validate a risk stratification model for function decline, COPD progression, and responses to EBV therapy.