Detection of malignant thymoma in primary tumor and metastatic lesions using 99mTc-tetrofosmin scintigraphy

99mTc-tetrofosmin was developed as a myocardial perfusion imaging agent and can also be used to depict tumors. We have experienced five cases of malignant thymoma delineated on 99mTc-tetrofosmin SPECT. In one case significant activity was clearly detected in the primary tumor and metastatic lesions. In quantitative analysis, similar 99mTc-tetrofosmin and 201Tl-chloride uptake ratios were obtained (1.95+/-0.57 versus 2.27+/-0.85, respectively; n.s.). The ability of 99mTc-tetrofosmin to detect malignant thymoma was comparable to that of 201Tl-chloride. Therefore, 99mTc-tetrofosmin might be a useful tracer for the detection of malignant thymoma, although more studies will be required to evaluate its diagnostic accuracy.