Technetium-99m tetrofosmin single photon emission computed tomography in the evaluation of suspected lung cancer

Technetium-99m-tetrofosmin is a radiopharmaceutical employed for myocardial imaging, which has recently emerged as useful in the visualization of tumours. In this study technetium-99m-tetrofosmin was evaluated for its accuracy in differentiating malignant from benign pulmonary lesions, and in detecting mediastinal node metastasis due to lung cancer. Eighty-one patients with a solitary lung lesion of the chest radiograph and/or CT scan were submitted to chest single photon emission computed tomography after technetium-99m-tetrofosmin injection (740 MBq i.v.). The scintigraphic findings were correlated to the final histopathological diagnosis, demonstrating abnormal tracer accumulation in 51 of 54 malignant (sensitivity 94%) and in 4 out of 27 benign conditions (specificity 85%), yielding an accuracy of 91%. Mediastinal lymph-node involvement was evaluated in 35 patients with non small cell lung cancer who underwent mediastinoscopy and/or surgery. Tetrofosmin accuracy (89%) was significantly higher than that of CT (69%), p <0.05); the false negative scintigraphic results were in nodes sized less than 1 cm. In conclusion, technetium-99m-tetrofosmin imaging is useful in distinguishing malignant from benign pulmonary lesions, and in non- invasively assessing mediastinal node metastases from non small cell lung cancer, especially in patients with enlarged nodes by CT scan.