Mediastinal evaluation in lung cancer.

Findings of mediastinal imaging were compared with pathologic findings following thoracotomy and full nodal sampling in 50 patients with bronchogenic carcinoma. All patients underwent full nodal sampling and chest radiography, conventional tomography, CT, and Ga-67 radionuclide scanning. The highest sensitivity for mediastinal metastases noted was 54%, considering nodes greater than or equal to 1.0 cm abnormal at CT. The small size of some involved nodes precluded sensitivity from reaching 100%. Using differing size criteria for nodal abnormality at CT (greater than or equal to 1.0 cm, greater than or equal to 1.5 cm, greater than or equal to 2.0 cm abnormal) sensitivity decreased as specificity increased. The highest specificity noted was 97% with CT, considering nodes greater than or equal to 2.0 cm abnormal. Ga-67 scanning did not offer additional information when compared with that of other studies. The predictive value of considering mediastinal lymph nodes greater than or equal to 1.0 cm abnormal at CT was 35%. Reasons for this include reactive nodes proximal to obstructions and prior granulomatous disease. In 13 peripheral T1N0 cancers (determined by chest radiography) no additional information was gained with any other imaging technique. The utility of CT in peripheral T2 cancers and central cancers is not clear.