Radio-opacity of the paranasal sinuses. Conventional views and CT.

In order to examine the reliability of conventional views in predicting the degree of radio-opacity, irrespective of soft tissue or fluid seen in chronic sinusitis in adults, a comparison has been made between the results of evaluations by two routine views (Caldwell's and Waters') and by CT in axial scans. Ninety-seven sides (61 case) were included in the study. The radio-opacity was classified into three groups according to the degree of aeration or radiolucency. The diagnosis of plain films were classified into three categories (matched diagnosis, over-diagnosis, and under-diagnosis) in comparison to the radio-opacity depicted by corresponding CT scans. The incidences of matched diagnosis are, in the order of percentages: maxillary sinus (78.4%), frontal sinus (71.1%), nasofrontal area (66.0%), anterior ethmoidal cells (52.6%), and posterior ethmoidal cells (52.6%). The incidence of over-diagnosis is highest in the posterior ethmoidal cells (52.6%) and lowest in the maxillary sinus (20.6%). The incidence of under-diagnosis is highest in the anterior ethmoidal cells (24.7%) and lowest in the maxillary sinus (1.0%).