Computed tomographic imaging to determine the frequency of anatomical variations in pneumatization of the ethmoid bone.

The present study was performed on axial and coronal CT scans of 212 patients. Scans were analyzed by an anatomist and a radiologist for the presence of Haller's cells, agger nasi cells, Onodi's cells and pneumatized crista galli. Results demonstrated the presence of Haller's cells in 21.2%, Onodi's cells in 10.4% and pneumatized crista galli in 2.4% of patients. A pneumatized anterior clinoid process was found in 0.5% of the patients. The data obtained in our study were compared with those reported in other anatomic and radiologic studies.