Computed Tomographic Study of Frontal Sinus Cells and Opacification as Per the International Frontal Sinus Anatomy Classification.

Introduction: International frontal sinus anatomy classification (IFAC) was introduced in 2016 to standardize the nomenclature of the cells in the frontal recess region, facilitate better communication between surgeons and precision in surgical planning, and improve surgical teaching. This study aims to estimate the radiological prevalence of the different frontal recess cells according to the IFAC and to evaluate the relationship of these cells with the frontal sinus opacification in patients with chronic rhinosinusitis.

Methods: In this study, 90 participants diagnosed with chronic rhinosinusitis (CRS) who underwent computed tomogram (CT) of the para nasal sinuses were enrolled consecutively. The CT images were were studied in detail using RadiAnt DICOM viewer. The frontal recess cells were grouped as per the IFAC guidelines and their respective prevalence was calculated. The frontal recess cells were grouped as per the Opacification or mucosal thickening within these cells and the frontal sinuses were noted. A multivariate logistic regression analysis was done to evaluate the association between frontal sinus opacification and presence of various IFAC cells.

Results: A total of 640 IFAC cells were documented in 180 sides, of which 326 were anterior cells, 263 were posterior cells and 51 were medial cells. The most prevalent cell was the agger nasi cells(ANC), present in 91.7% of 180 sides, the supra agger nasi cells(SANC), Supra agger nasi frontal cells(SAFC), supra bulla cells(SBC), supra bulla frontal cells(SBFC), supra orbital ethmoidal cells(SOEC) and frontal septal cells(FSC) were present in 47.8%,37.8%, 65.6%,28.9%, 51.1% and 28.3% respectively. There was no significant association of presence of IFAC cells and frontal sinus opacification except for SBFC(p = 0.038). A significantly higher number of diseased frontal recess cells were seen with involved frontal sinuses when compared with non-involved frontal sinuses across all types of IFAC cells.

Conclusion: The ANC were the most prevalent among all the IFAC cells and the FSC were the least prevalent. There was no significant association with the presence of different types of IFAC cells and frontal sinus opacification except for SBFC. However, there was a significantly higher number of diseased IFAC cells associated with frontal sinus opacification than in those without frontal sinus opacification.