Study of Normal Fissures Seen on Posteroanterior and Left Lateral Chest Radiographs

This study included consecutive 318 pairs of posteroanterior (PA) and left lateral (LL) chest radiographs taken under routinely used conditions with the patients in erect position. Major, minor and accessory fissures visualized on these ra-diographs were described according to their visibility, position , length and shape. On PA chest radiographs, superolateral major fissures in 54 (17%), superomedial major fissures in 20 (6%), minor fissures in 234 (74%), inferior accessory fissures in 19 (6%), superior accessory fissures in 12 (4%), left minor fissures in 16 (5%) and azygos fissure in 2 (0.6%) patients were seen. On LL chest radiographs, 266 (84%) right major fissures, 242 (76%) left major fissures, 210 (66%) minor fissures and 6 (2%) superior accessory fissures were seen. We have described the frequencies of various orientations, shapes and lengths of these fissures. This study not only supports the common knowledge of the appearances of pulmonary fissures but also explains numerically the various frequencies of these common patterns and variations seen in practice. the LL radiographs, the right major fissure appears more oblique and ends in a more anterior position inferiorly, merges with the right hemidiaphragm, and often joins with the minor fissure (1). The minor fissure is more constant in its visualiza-tion on PA and LL chest radiographs. Its lateral portion is more often seen than the medial (4). Part of the minor fissure may become vertical medially (5) Various accessory fissures may also be seen on PA or LL chest radiograph. These include azygos (6), inferior accessory (7), superior accessory (8) and left minor fissures (9). The normal appearances of the major fissures and their variants have been described extensively and correlated with the CT findings (10). To our knowledge, there has been no previous study that has described the pulmonary fissures in quantitative details or the frequencies with which various shapes, orientations, sizes and relationships of various fissures may be seen. The aim of this study was to enumerate the common patterns of visualization of pulmonary fissures and to describe the frequencies with which these patterns are seen on the PA and LL chest radiographs.