DIFFUSE NODULAR LUNG-DISEASE ON CHEST RADIOGRAPHS - A PILOT-STUDY OF CHARACTERIZATION BY FRACTAL DIMENSION

OBJECTIVE. We present a computer-aided diagnostic technique for identi fying nodular interstitial lung disease on chest radiographs. The frac tal dimension was used as a numerical measure of image texture on digi tal chest radiographs to distinguish patients with normal lung from th ose with a diffuse nodular interstitial abnormality. MATERIALS AND MET HODS. Twenty digitized chest radiographs were classified as normal (n = 10) or as containing diffuse nodular abnormality (n = 10) on the bas is of readings assigned according to the classification of the Interna tional Labour Organization. Regions of interest (ROIs) measuring 1.28 cm(2) were selected from the intercostal spaces of these radiographs. The fractal dimension of these ROIs was estimated by power spectrum an alysis. The cases were not subtle. RESULTS. The fractal dimension prov ided statistically significant discrimination between normal parenchym a and nodular interstitial lung disease. The area under the receiver o perating characteristic curve was 0.90 (+/-0.02). One operating point provides sensitivity of 88% with a specificity of 80%. CONCLUSION. The fractal dimension can provide a measure of lung parenchymal texture a nd shows promise as an element of computer-aided diagnosis, characteri zation, and follow-up of interstitial lung disease.