CT MOSAIC PATTERN OF LUNG ATTENUATION - DISTINGUISHING DIFFERENT CAUSES - PICTORIAL ESSAY

Areas of variable lung attenuation in a lobular or multilobular distri bution are occasionally seen on CT or high-resolution CT scans of the lungs [1], although never as a normal finding. This mosaic pattern of lung attenuation presents a challenge to the radiologist when deciding which are the abnormal regions of lung-those of law attenuation, thos e of high attenuation, or both, We have observed three categories of d isease known to cause a CT mosaic pattern of lung attenuation: small-a irway disease, vascular lung disease, and infiltrative disease. Diseas es from each of these categories can cause similar patterns of mosaic lung attenuation on CT scans. However, it is sometimes possible to dis tinguish among these categories by using additional CT findings. We il lustrate the known causes of a CT mosaic pattern of lung attenuation a nd highlight distinguishing features.