Analysis of the fossa olfactoria using cone beam tomography (CBT)

A cone beam tomography (CBT) examination of the olfactory area with its different variants allows development of an individual anatomical-radiological risk profile of the ethmoid and the identification of so-called 'dangerous ethmoids.'

Preoperative imaging performed with high-resolution CBT is imperative for analysis of the risk of injuring the olfactory fossa during sinus surgery. This study aimed to analyze the relevant parameters.

This was a retrospective, single-center study of 141 patients. The Accu-I-Tomo F17 was used. Keros type, the point of the anterior ethmoid artery, and the angle between the lateral lamella and the cribriform plate (α(lc)) were evaluated.

The Keros types were distributed as follows: type I, 13% (α(lc): 131°); type II, 64% (α(lc): 116°); type III, 23% (α(lc): 108°) (p < 0.001). The angle of the olfactory fossa and the position of the anterior ethmoid artery (free course: α(lc)=112° vs integrated into the skull base: α(lc)= 120°) was significantly different.

Surgical procedures in Keros type III where the height of the lateral lamella is much longer than in type II or type I, with an angle of nearly 107° between the lateral lamella and the cribriform plate, are expected to be safer in comparison with Keros type II with 116° and Keros type I with 131°.