Radionuclide imaging of thoracic malignancies.
Image Interpretation, Computer-Assisted
Over the past decade a variety nuclear medicine imaging studies have become available that are of considerable value to patients who have pulmonary malignancies. By far the greatest impact on the management of patients who have thoracic malignancy has been the availability of 18FDG-PET imaging. In the patient who has newly diagnosed lung carcinoma, 18FDG-PET improves the accuracy of staging the disease by identifying or excluding mediastinal disease and distant metastatic foci. 18FDG-PET is superior to anatomic methods for evaluating the response to therapy and for distinguishing recurrent disease from posttreatment changes. Studies are in progress to evaluate the role of 18FDG-PET imaging in assessing prognosis. In patients who have bronchial carcinoid, somatostatin receptor imaging with 111In-DTPA-pentetreotide (Octreoscan) can help identify patients who are candidates for curative surgery, detect unsuspected metastatic spread, and identify patients who might benefit from certain types of medical therapy. Although it was initially speculated that 18FDG-PET imaging would not be sensitive for tumor detection in patients who have neuroendocrine tumors because of the usual slow metabolism and biology of these tumors, many neuroendocrine tumors are positive on 18FDG-PET imaging. Nevertheless, there has been no direct comparison of 18FDG-PET imaging and somatostatin receptor imaging, nor does a positive or negative 18FDG-PET image exclude neuroendocrine tumor. 18FDG-PET imaging and somatostatin receptor imaging with (99m)Tc-depreotide (Neotect) are safe, cost-effective methods that are valuable in the diagnosis and management of patients who have suspected or known lung cancer. 18FDG-PET and (99m)Tc-depreotide imaging have a high degree of sensitivity, specificity, overall accuracy, and positive and negative predictive values in the evaluation of the solitary pulmonary nodule. These agents provide noninvasive, cost-effective methods for selecting patients for aggressive intervention without contributing to increased morbidity. Both methods have incremental value over CT imaging in selecting patients who have solitary pulmonary nodules for invasive biopsy or for thoracotomy.