The role of computed tomography in the diagnosis and management of lung cancer. An overview.

Computed tomography (CT) is now established as the principal radiographic adjunct to plain film examination in the diagnosis and management of lung cancer. It should be used in the evaluation of every pulmonary nodule to determine whether the nodule is solitary and whether mediastinal metastases are present and to evaluate the mass by assessing its density. In general, nodules with Hounsfield numbers greater than +175 can be presumed to be calcified and, hence, benign. CT is of great value in determining the extent of lung cancer and at present the best imaging modality for evaluating mediastinal lymph nodes. Spread of tumor to mediastinal nodes is evaluated on the basis of node size. Nodes less than 1.0 cm in diameter are considered normal, 1.0-1.5 cm suspicious for tumor, and greater than 1.5 cm have a high probability of being malignant. Node size, however, is dependent on location in the mediastinum and whether infection is present in the lung. Size criteria alone should not be used to deny surgery.