Subcarinal lymph node enlargement: radiographic findings and CT correlation.

Detection of subcarinal lymph node enlargement on the posteroanterior chest radiograph was assessed in 90 patients who also had computed tomography (CT). Sixty of the 90 patients had normal-sized and 30 had enlarged (greater than 15 mm diameter) subcarinal lymph nodes on CT. An abnormality in the contour of the azygoesophageal recess interface was present on plain radiographs in only 23% of patients with lymphadenopathy; increased subcarinal opacity was present in 40%. The external surface of the medial wall of the right main-stem bronchus and bronchus intermedius was visible in 87% of patients with normal-sized lymph nodes but in only 27% of patients with lymphadenopathy. CT showed that the medial wall of the right main-stem and intermediate bronchi normally is delineated laterally by air within the bronchus and medially by lung or subcarinal fat. Nonvisualization may be due to replacement of lung or fat by enlarged nodes or tumor and may be helpful in assessing patients with suspected subcarinal adenopathy.