CT signs and patterns of lung disease

A "sign" on CT scanning of the lung refers to a radiologic finding that sug gests a specific disease process. Understanding the meaning of a sign impli es an understanding of the findings on the CT scan. Knowing the name of the sign is not as important as recognizing the radiologic findings, and under standing the meaning of the findings, but is useful when communicating with clinicians and radiologists who may use the term. A CT "pattern" refers to a nonspecific finding or collection of findings suggesting one or more spe cific disease processes. This article reviews some of the more common and u seful CT signs and patterns of focal and diffuse lung disease.