Several early studies have compared roentgenological features of emphysema with necropsy-assessed disease.3-9
These papers were mainly descriptive and emphasize different imaging aspects of emphysema, and a general consensus was never reached. Nevertheless, the papers contain important information. Features of hyperinflation on CXR include increase in the retrosternal space and depression of the diaphragm, i.e. location of the right hemidiaphragm at or below the anterior end of the 7th rib.10 Nicklaus et al.6 found that diaphragmatic flattening (or even concavity) in the lateral projection was the most accurate sign of overinflation (Figure 21.1). In
the posteroanterior view the contour of the diaphragm is more important in the diagnosis of overinflation than its position based on rib level.5,11 However, population-based studies of imaging in COPD do not exist, which means that published frequencies and correlations must be interpreted with caution.