Investigation of Distances Between the Anterior Nasal Spine and Nasofrontal Beak, Basal Lamella, Skull Base, and Sphenoid Sinus on Paranasal Sinus Computed Tomography.

Objective: The aim of this study was to investigate the distances between the anterior nasal spine and basal lamella (BL), skull base, nasofrontal beak (NfB), and the anterior wall of sphenoid sinus on computed tomography (CT) images.

Methods: A total of 160 patients who were seen at the otolaryngology clinic of our institution were evaluated with the help of the image processing software of the radiology department. Cases in which bony structures could not be seen clearly because of previous surgery or trauma were excluded. The distance between the anterior nasal spine; and NfB, the closest point of the skull base in the frontal recess (SB1), the closest point of the BL, the intersection of the line with which the distance to the BL was measured with the skull base (SB2) and the closest point of the anterior wall of the sphenoid sinus (Sp) were measured using multiplanar reconstruction.

Results: The images of 140 patients were examined. NfB, SB1, BL, SB2, and Sp were 5.14 ± 0.46 (4.15-6.38) cm, 5.70 ± 0.48 (4.31-7.03) cm, 4.84 ± 0.44 (3.86-5.98) cm, 6.23 ± 0.50 (5.13-7.35) cm, and 6.14 ± 0.46 (5.04-7.36) cm, respectively.

Conclusion: In our study group, the distances some of which were reported as constant values in the literature were found to have a range of up to 2 cm. Therefore, if distances between structures are to be used for orientation during endoscopic sinus surgery, they should be better measured preoperatively on paranasal sinus CT scan images instead of using predefined constant values.