INFERIOR HILAR WINDOW

The authors undertook a study to determine the ability to detect mass or adenopathy in the "inferior hilar window", a normally avascular region inferior to the shadow of the right pulmonary artery and vein and anterior to the descending left pulmonary artery on lateral chest radiographs. Fifty patients with normal results of thoracic computed tomography (CT) and 25 with unilateral or bilateral hilar masses or adenopathy (defined as opacity > 10 mm in diameter) were selected retrospectively. Patients with concomitant pulmonary masses or consolidation at CT that might be confused with or obscure an inferior hilar mass or adenopathy were excluded from study. The 75 corresponding lateral chest radiographs were then evaluated blindly. Forty-seven of the 50 normal cases were correctly interpreted (specificity = 94%). The anterior walls of the right and left lower lobe bronchi were seen in 36% and 84% of normal cases, respectively; the average thickness was 2 mm. Of the 25 patients with inferior hilar masses, 22 were recognized as having abnormalities (sensitivity = 88%); two of the three patients with false-negative results had right hilar masses. Overall accuracy was 92%. For only eight (32%) of the 25 patients was the laterality of abnormality correctly diagnosed. Evaluation of the inferior hilar window on lateral chest radiographs is accurate in assesing the presence or absence of inferior hilar mass or adenopathy.