[Volumetric measurement of the maxillary sinus by coronal CT scan]

The volume of the maxillary sinus was estimated by coronal CT scan. The purpose of this study was to compare the estimated volume of the normal maxillary sinus with that of the inflamed maxillary sinus. Patients were classified following evaluation by CT scan of the paranasal sinuses into 3 categories. Group A: Patients suffered from headache, facial pain and epistaxis, but CT scans of their nasal cavity and paranasal sinus were within normal limits without inflammatory change; 102 patients (40 males and 62 females, aged 15-80 years, mean 49.1). Group B: Patients with bilateral chronic maxillary sinusitis, CT scans of whom showed inflammatory changes in both maxillary sinuses. All of the patients in this group underwent sinus surgery after coronal CT scans; 69 patients (38 males and 31 females, aged 15-68 years, mean 44.7) Group C: Patients with unilateral chronic maxillary sinusitis, CT scans of whom showed inflammatory change in unilateral maxillary sinuses; 14 patients (6 males and 8 females, aged 16-71 years, mean 43.2) CT scans of these patients were measured by Plannimeter to take the area of each image of the maxillary sinus. Consecutively imaged areas were summated by integral calculus to obtain an estimate of the sinus volume. Group A normal cases had a mean maxillary sinus volume of 20.5 +/- 9.2 ml (M +/- SD), and Group B bilateral maxillary sinusitis patients had a volume of 17.3 +/- 7.6 ml. The mean maxillary sinus volume in the bilateral chronic maxillary sinusitis patients (group B) was significantly smaller than that in the normal cases (group A) (p < 0.01, t-test). In both groups A and B, the mean of the maxillary sinus volume in males was significantly greater than in females (p < 0.01, t-test), and patients aged from 20 to 29 years old had the largest volume of all the age group. Group C patients with unilateral maxillary sinusitis had a mean maxillary affected sinus volume of 24.2 +/- 7.7 ml, and contralateral normal sinuses with a mean volume of 26.9 +/- 9.3ml. The mean maxillary sinus volume in the affected sinuses was significantly smaller than those in the contralateral normal sinuses (p < 0.05, Wilcoxon-test). The various volumes of the maxillary sinuses and the developmental cause were discussed. Comparison of groups A with B suggested three distinct patterns; 1. the maxillary sinus volume has decreased due to inflammatory changes in the bone; 2. the small sinuses have a tendency to develop chronic inflammatory change; 3. the aeration in the maxillary sinus may be decreased when anatomic variations that may obstruct the ethmoid infundibulum exist.