PRIMARY LUNG-CANCER SPECT IMAGING WITH PENTAVALENT TECHNETIUM-99M-DMSA

To assess the clinical role of Tc-99m(V)-DMSA in primary lung cancers, SPECT imaging was performed on 31 patients with suspected lung cancer. Methods: Planar and SPECT images were obtained at 3 to 4 hr after intravenous injection of approximately 555 MBq Tc-99m(V)-DMSA. Two uptake ratios (the maximum counts/pixel in the lesion to the average counts in normal tissue) were calculated. Results: Various types of primary lung cancers (adenocarcinoma, squamous-cell carcinoma, small-cell carcinoma, large-cell carcinoma and bronchial carcinoid tumor) were imaged by Tc-99m(V)-DMSA SPECT. Approximately 90% of the lung carcinomas showed increased uptake and were clearly demonstrated by SPECT images. Four cases incidentally revealed osseous metastatic lesion. Three benign lesions did not show increased uptake. Three cases were false-negative and there were no false-positive cases for the primary lesions. Conclusion: Technetium-99m(V)-DMSA SPECT images demonstrated approximately 90% of the primary lung cancers. Uptake ratios were higher in squamous-cell carcinomas than adenocarcinomas. Evaluation of mediastinal tumor extension and nodal metastatic lesion was very difficult by high blood-pool activity in the major cardiovascular structures due to slow blood-pool clearance. However, Tc-99m(V)-DMSA SPECT imaging was very useful for detecting primary lung cancers and metastatic lesions to the osseous structures.