No abstract

No abstract

The pulmonary fissures are highly variable and the right major fissure differs considerably from the left. The fissures are often incomplete.

The major fissure is an important anatomic landmark in the interpretation of chest radiographs and computed tomographic (CT) scans. At radiography, the major fissures normally appear as hairlines of soft-tissue density; at conventional CT, they typically appear as lucent, hypovascular bands; and at high-resolution CT, they most often appear as sharp lines. The superolateral major fissure usually manifests as a curving edge at the upper lateral lung field with lateral opacity and medial lucency. The vertical fissure line appears as a fine, linear shadow, commencing in or near the costophrenic angle and coursing upward. The superomedial major fissure manifests as a short, obliquely oriented straight line. Progressive widening of the major fissure inferiorly manifests as a triangular area of increased opacity and represents intrafissural fat. Various inflammatory, granulomatous, neoplastic, and abnormal hemodynamic conditions involving the major fissure can affect its imaging appearance. Oblique orientation of the major fissure may complicate radiographic interpretation. The fissure may be incomplete or absent, complicating identification of various diseases. An incomplete major fissure may lead to disease spread, collateral air drift, or the "incomplete fissure sign," a sign that may, however, also be present in cases of complete fissure. Knowledge of the anatomy and normal variants of the major fissures is essential for recognizing their variable imaging appearances as well as related abnormalities.

The ANN can provide a useful output as a second opinion to improve general radiologists' diagnostic performance in the differential diagnosis of certain diffuse lung diseases using HRCT.