Computed tomography of the major and minor fissures

One hundred computed tomograms of patients with normal lungs were reviewed to determine the normal characteristics of the major fissures and the minor fissure and how often each is seen. Each major fissure was imaged most often as a lucent band, less often as a line, and least often as a dense band. The percentage visualization of these three appearances is tabulated for the upper, middle, and lower parts of each major fissure. The minor fissure was imaged as a lucent area. The lucent area was more often triangular, with its apex at the hilar region, and less often round or oval. Several examples are presented to illustrate how an understanding of the fissures, as displayed cross-sectionally, helps in interpreting abnormal findings on computed tomographic scans. These examples relate to localization of masses within the lobes of the lung, extension of carcinoma to or across the fissure, recognition of fluid in the fissure, etc.