Early prediction and judgement of chemotherapeutic effects on the viability of malignant bone and soft tissue tumors with 201Tl scintigraphy

The study assessed the ability of Tl-201 scintigraphy to determine cell viability of malignant bone and soft tissue tumors before and after chemotherapy. First, biological kinetics of Tl-201 was examined in nude mouse models bearing Ewing's sarcoma. Tl-201 was rapidly taken up by tumors, depending upon blood flow. Tumor uptake of Tl-201 was significantly reduced after chemotherapy with cis-diamminedichloroplatinum [II] (CDDP). On the other hand, no tumor volume was seen up to 12 days after CDDP injection. Thus tumor uptake of Tl-201 was considered to be a more sensitive marker of tumor cell activity. Next, 19 patients with 21 lesions of bone and soft tissue tumors underwent Tl-201 scintigraphy. Tumor uptake of Tl-201 was scored in 5 degrees and compared before and after chemotherapy. Tl-201 uptake score was 2.00±0.89 in 6 lesions histologically judged as remarkably effective, 1.33±0.47 in 9 lesions judged as moderately effective, and 0.17±0.69 in the remaining 6 lesions judged as ineffective; there were significant differences in Tl uptake scores between both remarkably and moderately effective chemotherapeutic cases and ineffective cases. The concordance rate of Tl-201 scintigraphy with concurrently available X-ray CT and MRI was 79%. In conclusion, Tl-201 reflects tumor cell activity, allowing the early prediction and precise judgement of chemotherapeutic results in bone and soft tissue tumors. (N.K.)