Incomplete and accessory fissures of the lung evaluated by high-resolution computed tomography.

Purpose: The aim of our study was to assess incomplete and accessory interlobar fissures using volumetric thin-section high-resolution computed tomography (HRCT).

Materials And Methods: Retrospective assessment of HRCT examinations of 250 patients was performed. We assessed the localization, extension, and type of the incompleteness of fissures as well as the presence and localization of accessory fissures. We searched for possible correlation among the localization of interlobar fissures, the presence of incompleteness, and accessory fissures.

Results: On the left side, an incomplete oblique fissure was found in 24%. The discontinuity was present in the parahilar region and the area of the incompleteness was most frequently between 21% and 40%. The right oblique fissure was incomplete in 35%, mostly parahilarly, with the most frequent discontinuity below 20%. An incomplete horizontal fissure was found in 74%. Accessory fissures were identified in 16% of patients, with the same frequency on both sides. The most frequent finding was accessory horizontal fissure with 8.0% on the left side, superior accessory fissure (7.2%) and inferior accessory fissure (5.2%) on the right side. No correlation was found among the localization of interlobar fissures, the presence of incompleteness, and accessory fissures.

Conclusion: Incomplete and accessory fissures are frequent anatomic variations of interlobar fissures.