Accuracy of the plain radiograph in the detection of aortopulmonary lymphadenopathy

Detection of aortopulmonary window lymph node enlargement by chest radiography was assessed in 67 patients with bronchogenic carcinoma. All patients underwent computed tomography (CT). Surgical confirmation of the radiographic and CT findings was available in all patients with lymph node size smaller than 2.5 cm in diameter on CT (47 patients) and in 6 of 20 patients with nodes greater than 2.5 cm in diameter. Forty-one had normal-sized and 26 had enlarged (greater than 1.5 cm diameter) aortopulmonary nodes. Lymphadenopathy was detected on the chest radiograph in 21 of the 26 patients with enlarged nodes. It was wrongly suspected in one of the 41 patients with normal-sized aortopulmonary nodes on CT. Three patients with lymphadenopathy had a normal aortopulmonary window on the chest radiograph. In these patients, the nodes measured 1.6-2.6 cm in diameter. In two patients with enlarged nodes and in two with normal-sized nodes, the aortopulmonary window could not be assessed on the radiograph because it was obscured by concomitant atelectasis and obstructive pneumonitis of the left upper lobe. We conclude that in the absence of left upper lobe atelectasis, chest radiography has a high sensitivity (87%) and specificity (97%) in detecting aortopulmonary lymph nodes larger than 1.5 cm in diameter. In only one patient was metastatic disease detected at surgery in a node smaller than 1.5 cm diameter.