Nasolacrimal system aeration on computed tomographic imaging: effects of patient positioning and scan orientation

Purpose: To determine the impact of patient positioning and scan orientation on the appearance of air in the nasolacrimal drainage system on computed tomography (CT) imaging, and the repeatability of the observations. Methods: This was a retrospective analysis of CT images for 92 patients. Results: Air was found to be present more fully in the upright-position group as compared with the supine-position group. Comparing axial and coronal scan orientation, no difference in aeration was found, except for the nasolacrimal duct in the upright-position group. Conclusion: Patient position should be accounted for in diagnostic conclusions and treatment decisions based on CT.