Keros Classification

Keros Classification in CT scan of the paranasal sinuses

Measures depth of the olfactory fossa
Measurement: Distance from the lamina cribrosa to the roof of ethmoid (highest point) Note: Depth of the olfactory fossa can be asymmetrical Note the measurement (double-head arrow)
Keros type	Measurement	Illustration
1	1-3 mm	Keros type 1: notice relatively shallow olfactory fossa
2	4-7 mm	Keros type 2: Deeper olfactory fossa
3	8-16 mm	Keros type 3: Deep olfactory fossa
Implication: Stratifies the risk of intracranial penetration during ENT surgery