Large-Scale Three-Dimensional CT Mapping of the Frontal Sinus Drainage Pathway: Anatomical Relationships and Surgical Validation

BackgroundThe frontal sinus drainage pathway (FSDP) includes the frontal recess as its most anatomically complex segment, where surrounding cell pneumatization can influence drainage patterns. Despite this variability, large-scale 3-dimensional characterization of the drainage pathway in both opacified and nonopacified sinuses remains limited, particularly with operative validation.ObjectiveTo perform 3-dimensional mapping of the FSDP and evaluate its relationship to adjacent cells, focusing on drainage patterns associated with frontal sinus opacification.MethodsThis single-center cross-sectional study analyzed 1008 frontal sinuses using 3-dimensional computed tomography reconstruction software. Frontal recess cells were classified according to the International Frontal Sinus Anatomy Classification. The course of the FSDP relative to adjacent cells was mapped and compared between opacified and nonopacified sinuses. A subset of 112 opacified sinuses that underwent endoscopic frontal sinus surgery was included for surgical validation, with preoperative mapping correlated with intraoperative findings.ResultsThe FSDP most frequently coursed posterior to the agger nasi cell (63.9%). In the presence of supra-agger cell and supra-agger frontal cell, it predominantly followed a medial course (55.3% and 68.7%, respectively). It consistently ran anterior to supra-bulla cell (100%), lateral to frontal septal cell (100%), and most commonly anterior to supra-bulla frontal cell and supraorbital ethmoid cell (79.7% and 97.3%, respectively). Pathway-cell relationships did not differ between opacified and nonopacified groups. Preoperative 3-dimensional mapping showed high intraoperative concordance.ConclusionThis study demonstrates that the anatomical configuration of the FSDP is largely consistent across both opacified and nonopacified sinuses. These findings provide a structured 3-dimensional anatomical framework that may assist preoperative assessment and surgical orientation in endoscopic frontal sinus surgery.