ABSTRACT
Chronic obstructive pulmonary disease (COPD) is characterized by functional abnormalities and considered a slowly progressive airway obstructive disorder resulting from some combination of pulmonary emphysema and irreversible reduction in the caliber of small airways in the lung. Although responsible for some changes observed on radiographs, chronic bronchitis defined as a clinical disorder is not a radiological diagnosis. By contrast, emphysema is defined as an anatomical disorder and is best detected by chest radiography and high-resolution computed tomography (HRCT). As surgical treatment of emphysema advances, it becomes necessary to characterize emphysema in an objective and reproducible manner. Because it is possible that medical treatment for COPD in its early reversible stages may soon be available, it would be helpful to be able to detect emphysema before symptoms or physiological consequences have developed. A number of recent and evolving pulmonary imaging methods have the potential to provide quantitative, volumetric measures of emphysema, including both morphologic as well as functional displays of regional ventilation/perfusion abnormalities. Some of these new methods are investigational and require further improvement, validation and clinical trials.
