- Methods of measuring ethmoid infundibulum dimensions, maxillary sinus natural ostium diameter, and deviated nasal septum. A) Ethmoid infundibulum width was defined as the line between uncinate process and bullae ethmoidalis. B) Ethmoid infundibulum length was defined as the uncinate process length from its free edge to the attachment above the inferior turbinate on coronal CT. C) Maxillary sinus natural ostium diameter was defined as the length of a line drawn between the uncinate process attachment and the bony part of the orbit floor or anterior ethmoid air cells. (D) Deviated nasal septum was defined as a deviation of >10 degrees from a vertical line from the crista galli to the nasal floor.