[CT evaluation of pulmonary metastases: usefulness in comparison with chest radiography]

The purpose of this study was to evaluate the usefulness of follow-up CT for screening pulmonary metastases, in comparison with chest radiography (CXR). Two hundred sixty CT examinations performed on 200 patients with known malignancy formed the basis of the study. One hundred sixty-five metastatic nodules were detected from 52 CT examinations in 36 patients. The detectability of these nodules on CXR was relatively good, but it was better on CT, which detected more nodules of smaller size, those overlying the mediastinum or hilus, and those showing ground-glass attenuation. As for the relationship between treatment and pulmonary metastases, pulmonary metastases treated surgically were detected on CXR in all patients. Pulmonary metastases showed a tendency to recur within one year after the initial treatment. The author concluded that routine CT to screen occult lung metastases in every patient with malignancy is not cost-effective. However, CT may be added at the start of the initial treatment and within one year thereafter, particularly for patients with lung cancer.