Diagnostic imaging in metastatic lung disease

Chest radiographs, full lung tomography and computed tomography of the chest provide increasing sensitivity for evaluation of pulmonary metastases. Pulmonary nodules of 5-10 mm diameter are detectable with increasing frequency by use of high kilovoltage chest radiographs. Full lung linear tomography provides an overall accuracy of 72-97% in diagnosis of pulmonary nodules. Chest CT delineates pulmonary nodules as small as 3 mm within 10 mm slice sections. However, as sensitivity increases, specificity diminishes in identifying metastatic nodules. Sensitivity in CT is also reduced by false negative findings due to unequal respiratory cycles. Comparative radiologic-pathologic evaluation of nodule detection proved CT to be the most sensitive screening method for pulmonary metastases. Timing of follow-up studies for pulmonary nodule detection in cancer patients can be determined by tumor growth kinetics; 3-6 month intervals proved to be useful.