Uptake of Tc-99m-tetrofosmin, Tc-99m-MIBI and Tl-201 in malignant thymoma

Tc-99m-tetrofosmin, Thallium-201-chloride (Tl-201) and Tc-99m-MIBI imagings were performed in a patient with malignant thymoma. Tracer uptake in the p rimary tumor was demonstrated. The tumor-to-background ratios of planar and SPECT imagings were 1.60 and 1.98 for Tc-99m-tetrofosmin, 1.12 and 2.09 fo r Tl-201, and 1.19 and 1.80 for Tc-99m-MIBI, respectively. In another patie nt Tc-99m-tetrofosmin and Tl-201 imagings were performed. Not only the prim ary tumor but also the direct invasions and metastatic lesions (bone metast ases) were clearly detected. The tumor-to-background ratios of planar and S PECT imagings were 2.31 and 2.78 for Tc-99m-tetrofosmin and 2.45 and 3.58 f or Tl-201, respectively. In 99mTc-tetrofosmin scintigraphy we acquired dela yed images, and the tumor-to-background ratios of planar and SPECT delayed images were 1.20 and 1.86, the retention ratios were -1.11 and -0.92 and th e retention indices were -48.1 and -33.1, respectively. Our preliminary res ults suggest that Tc-99m-tetrofosmin is useful in detecting not only the pr imary tumor but also metastatic lesions from malignant thymoma.