EVALUATING BENIGN AND MALIGNANT BONE AND SOFT-TISSUE LESIONS WITH TECHNETIUM-99M-MIBI SCINTIGRAPHY

This study compares the ability of Tl-201 and Tc-99m-MIBI to detect an d assess tumor response to chemotherapy in malignant and benign bone a nd soft-tissue lesions. Methods: Forty-two patients with various bone and soft-tissue pathologies (29 malignant and 13 benign lesions) were studied with Tl-201 and Tc-99m-MIBI. Planar Tl-201 scintigraphy was pe rformed 15 min after injection of 111 MBq of Tl-201. Within 1 wk of th e Tl-201 study, radionuclide angiography with 600-740 MBq of Tc-99m-MI BI was performed and planar imaging was done 15 min later. Results: In visual analysis, 31 of 42 patients showed similar uptake of both trac ers, 8 showed more intense uptake of Tc-99m-MIBI than Tl-201 and 3 sho wed more intense uptake of Tl-201 than Tc-99m-MIBI. In quantitative an alysis, similar Tl-201 and Tc-99m-MIBI uptake ratios were obtained (1. 96 +/- 1.25 versus 1.96 +/- 1.02, respectively; p = ns). The perfusion index derived from Tc-99m-MIBI radionuclide angiography was higher th an Tc-99m-MIBI uptake ratio (2.33 +/- 1.23 versus 1.96 +/- 1.02, respe ctively; p < 0.005), but correlated well with Tc-99m-MIBI uptake ratio (r = 0.75). In 11 patients with malignant tumors, Tl-201 and Tc-99m-M IBI scintigraphy was repeated after chemotherapy and the uptake of bot h tracers was significantly suppressed in patients with complete respo nse confirmed by histological evaluation. In patients with complete re sponse (n = 3), the uptake ratio of both tracers was reduced by more t han 50%, whereas, less than 20% reduction of uptake ratio was observed in patients with nonresponse (n = 6). Conclusion: The ability of Tc-9 9m-MIBI to detect malignant and benign bone and soft-tissue lesions an d to assess tumor response to chemotherapy was comparable to that of T l-201. I, addition, blood flow could be assessed by radionuclide angio graphy with Tc-99m-MIBI. Technetium-99m-MIBI is a promising radiopharm aceutical for the evaluation of bone and soft-tissue lesions.