Volumetric study of sphenoid sinuses: anatomical analysis in helical computed tomography

The sphenoid sinus is the most inaccessible part of the face, being inside the sphenoid bone and closely related to numerous vital neural and vascular structures. The objective of this study was to analyze and evaluate the variation of anatomy and the volume of the sphenoid sinus using helical computed tomography and medical imaging software. A total of 47 helical CT scans of sinuses of male and female individuals aged 18-86 years were selected. The images were formatted using ITK-SNAP software, consisting of three steps: (1) segmentation; (2) volumetric analysis and (3) 3D reconstruction. The sphenoid sinuses were also classified according to Hammer, i.e., in conchal, pre-sellar, sellar and post-sellar types. A single investigator, who is specialist in dental radiology and was trained and calibrated, performed the volume and image analysis. After 15 days, the segmentations were repeated. The Dunn's multiple comparison test revealed significant differences in the volume rankings between the right and left sides (P = 0.0002), with the post-sellar type presenting the greatest volume on the right side compared to pre-sellar and sellar types. In the left sphenoid sinuses, the post-sellar type showed the greatest volume. The Lin's correlation coefficient showed excellent reproducibility values. According to the applied methodology, it was found that the volume of the sphenoid sinus was influenced by neither age nor gender (P > 0.005). There was difference in the volumes of sphenoid sinus on the right and left sides and in the anatomical classification.