OBJECTIVE. The purpose of this study was to compare the sensitivities and diagnostic accuracies of chest radiography and CT in the assessment of diseases of the trachea and main bronchi in regard to detection, evaluation of focal vs diffuse disease, separation of benign from malignant disease, and accuracy of diagnosis. MATERIALS AND METHODS. The chest radiographs and CT scans of 35 patients with proved diseases of the trachea and main bronchi and five control subjects were randomly assessed by two independent observers in a blind study. The diagnoses included 25 malignant and 1 0 benign conditions. The malignant lesions included 24 primary tumors and one metastatic melanoma. The benign lesions included two benign tumors, two tracheal stenoses, one focal amyloidosis, one tracheomalacia, and four miscellaneous diffuse abnormalities. The observers were asked to determine if an abnormality was present, to classify it as focal or diffuse and as benign or malignant, and to list the three most likely diagnoses. Sensitivities were compared by using the McNemar test. RESULTS. The sensitivity of both observers in detecting disease on the chest radiograph was 66%. The sensitivity on the CT scan was 97% for the first observer and 91% for the second observer (p < .01). Both observers were able to correctly classify the detected abnormalities as either focal or diffuse in 91% of cases on the chest radiographs and 97% of cases on the CT scans. The abnormalities were correctly classified as either benign or malignant in 78% of cases by both observers on the chest radiographs and in 85% and 78% of cases on the CT scans by the first observer and the second observer, respectively. The correct diagnosis was included in the list of the three most likely diagnoses in 61% of cases by both observers after reviewing the radiographs and in 56% of cases by one observer and 63% of cases by the other observer after reviewing the CT scans. CONCLUSION. CT is superior to chest radiography in allowing detection of abnormalities of the major airways. Both CT and chest radiography are accurate for differentiating focal from diffuse disease, but neither technique is accurate for distinguishing benign from malignant disease or for establishing a specific diagnosis.
