Identification and evaluation of centrilobular opacities on high-resolution CT

Abnormal findings on high-resolution CT that are localized to the centrilobular region imply primary disease of the small airways or primary peribronchiolar or perivascular pathology. We review methods of localizing abnormal opacity to the centrilobular region and discuss differential diagnostic considerations for centrilobular disease. Straightforward ways to differentiate between primary small-airways disease and peribronchiolar or perivascular conditions are also emphasized. Although perilymphatic disorders can also be associated with centrilobular opacities, these conditions have a distinctive appearance that warrants separate categorization; distinguishing characteristics of perilymphatic disorders with respect to the centrilobular conditions are discussed.