[The influence of maxillary sinusitis upon the posterior fatty layer--a CT investigation]

CT values were estimated at the fatty layer in contact with the posterior wall of the maxillary sinus in various condition, i.e., normal, sinusitis, postop. sinus, and mucocele. By the unilateral sinusitis (40 cases), CT values obtained by the affected sides were significantly higher than those of the non-affected normal sides. A single maxillary bone was used for experiments to show that the dense++ materials filing the sinus do not affect the CT values of the fatty layer, thus confirming the above clinical data was real and not artifact. In addition, by the mucocele of the maxillary sinus (9 cases) with negligible inflammatory change in the sinus, the CT values of the fatty layer did not show any remarkable increase such as seen by sinusitis. These data lead us to the impression that the increased density is due to the transmitted effects of maxillary sinusitis through the posterior wall. In postop, sinuses (11 cases) with various postop. periods, CT values were slightly higher than those in normal sinuses, suggesting that the sinus infection was under improvement. The enhancement performed by 14 cases (28 sides) showed increased density of the fatty layer, but the increase was similar in both affected and non-affected sinuses. This suggests that the increased rate of circulation at the fatty layer is not the contributory factor to higher CT values. The results described above, combined with the previous reports concerning the bony changes in sinusitis, will lead to the conclusion that the increased CT values at the fatty layer is caused by the direct engagement of the inflammatory conditions in the sinus cavities.