Morphometric study of the paranasal sinuses in normal and pathological conditions.

Prospective and retrospective morphometric CT (axial and coronal) research was performed with 100 healthy persons and 163 patients (145 males, 118 females, mean age 50 years, range 1-88 years). The patients were classified into the following groups: chronic sinusitis (n = 85), polyposis (n = 25), mucoceles (n = 13), benign tumors (n = 20) and malignant tumors (n = 20). After initial calibration with the scale (in cm) displayed on the CT image, each paranasal sinus was outlined following its bone inner surface. The data were processed with a high-resolution analysis system, and volumes were calculated using an integration areas rule. The ethmoid, maxillary and sphenoid sinuses exhibited an increase in volume for a period of up to 15 years, afterwards maintaining similar values. The frontal sinus grows in a monomodal pattern (peak at 30 years). The volumetric results (mean and standard deviation) in the normal adult group were as follows: maxillary sinus 13.07 cm3 (6.8), ethmoid 5.5 cm3 (2.0), sphenoid 3.5 cm3 (2.6) and frontal 3.7 cm3 (3.6). Primary frontal and maxillary sinus hypoplasia appeared in 3.9% and 1.3% of cases, respectively. The anatomic variations were as follows: concha bullosa 8.3%, Haller cells 3.2% and Onodi cells 8.3%. The sinusitis values (adults) were greater than those in the normal group: 14.4 cm3 (7.3), 6.8 cm3 (2.9), 2.9 cm3 (1.9) and 4.2 cm3 (5.2), with the exception of the sphenoid, but the difference was not statistically significant. Finally, we propose a new classification for paranasal sinus tumors (benign and malignant), volumetric T (vT), taking into account the morphometric tumoral volume and the mean volumetric value of normal sinuses.