A Radiological Study on the Grading System Based on the Position of Frontal Sinus Ostium in Koreans

Background and Objectives: Endoscopic frontal sinus surgery (EFSS) is much more challenging than endoscopic surgery on the other paranasal sinuses. Recently, a new computed tomography (CT) grading system according to the anatomical position of the frontal ostium was introduced. The purpose of this study is to apply the new CT grading system in Koreans. Materials and Methods: Sinus CT was performed on a total of 233 people, and a study was conducted on bilateral 466 sides. In this study, the parameters were included 1) frontal ostium grade (FOG): positive, neutral, and negative, 2) frontal ostium diameter (FOD), 3) four levels (I–IV) based on the FOG and FOD. Results: Overall, the FOG was 386 (82.8%) positive, 61 (13.1%) neutral, and 19 (4.1%) negative and the average FOD was 9.43±2.80 mm. When comparing men and women, there was no significant difference in the frequency of FOG, but in the mean of FOD, men were significantly longer than women. Overall, level I was 190 sides (40.8%), level II was 224 sides (48.1%), level III was 49 sides (10.5%), and level IV was 3 sides (0.6%). When comparing men and women, there was a significant difference in the frequency of levels. Conclusion: This is the first study to apply the new classification based on the FOG in Koreans. However, due to the limitations of this study, there is insufficient evidence to relate to the difficulty of EFSS because the actual operation time and operation success rate according to the new classification based on FOG were not evaluated. In the future, it is thought that further clinical studies based on the results of this study should be conducted.