Radiological Correlation Between the Frontal Sinus Ostium and the Nasal Choana

The frontal sinus is undoubtedly a great challenge; not only because of the anatomical variations of the frontal sinus ostium (FSO), but also because of the proximity of vital structures that can complicate dissection at this level. Consistent and easily identifiable landmarks and measurements could assist safe entry into the FSO. In this study, we identify standard distances from the choana to the posterior border of the FSO in males and females using high-resolution computed tomography (HRCT) scans. A total of 118 (left sides) sinus computed tomography scans were retrospectively selected and studied (unilateral analyses). The vertical and horizontal distances between posterior border of the FSO and nasal choana were measured using sagittal HRCT. The mean vertical distance from the posterior border of FSO to the choana was 31.18 +/- 5.62 mm and the mean horizontal distance from the posterior border of FSO to the choana was 40.87 +/- 6.02 mm. The measurements obtained in this study add anatomic knowledge that can serve as a better intraoperative localization of the FSO.