PULMONARY TC-99M TETROFOSMIN IMAGING - CLINICAL-EXPERIENCE WITH DETECTING MALIGNANT LESIONS AND MONITORING RESPONSE TO THERAPY

The authors prospectively investigated the uptake and kinetics of Tc-9 9m tetrofosmin (Tetro) in benign and malignant lung lesions and the ef fect of radiotherapy, chemotherapy, or both on Tc-99m Tetro uptake in malignant lung tumors. Dynamic and planar Tetro imaging were performed in 45 patients with pulmonary lesions during a period of 28 months (3 4 untreated malignant tumors, 11 benign lesions). Tetro uptake was vis ibly increased in 26 of 34 malignant tumors, with a mean lesion to con tralateral normal tissue ratio of 1.44 +/- 0.29 and a tumor washout ra te of 28.4 +/- 6.6% 30 minutes after injection. In 3 of 11 benign lesi ons, Tetro uptake was observed. Of the 26 patients with malignant tumo rs and positive Tetro uptake, nine had repeated imaging 6 to 8 weeks a fter therapy. The patients were treated with radiotherapy, chemotherap y, or both. Reduction in radiological tumor size was used as the clini cal response parameter. In five of nine patients, the course of Tetro uptake in follow-up imaging was in accordance with that of radiologica l tumor size. Two of four remaining patients had only slight discordan ce between the alteration of Tetro uptake and radiological tumor size. The sensitivity of Tetro to detect malignant lung lesions in our pati ents was 77%. The specificity and accuracy of the method were 73% and 76%, respectively. Tetro has limited diagnostic value in detecting lun g cancer. It may be useful to monitor the response to therapy in malig nant lung tumors with initial tracer uptake. Broader trials on this ma tter are needed for further clarification.