Performance Evaluation of Substitution Radiopharmaceutical according to Restriction of the Radiocolloids in Lymphoscintigraphy

Lymphoscintigraphy에 이용되는 방사성의약품의 사용제한으로 인한 대체 방사성의약품의 성능평가

Purpose: Several radioactive agents were used for lymphoscintigraphy in breast cancer. But recently, due to the change of local radiopharmaceutical licensing policy and discontinuation of supplies from manufacturer, we could not use many radiocolloids such as $^{99m}Tc$-Antimony Trisulfide Colloid, $^{99m}Tc$-Tin Colloid, $^{99m}Tc$-Human Serum Albumin. So it is necessary to use the substitution radiopharmaceutical. Therefore, this study aims to evaluate the performance of substitution radiopharmaceutical ($^{99m}Tc$-Phytate) including the existing radiocolloids and to set up of the appropriate protocol in lymphoscintigraphy. Materials and Methods: For each radiocolloids ($^{99m}Tc$-Antimony Trisulfide Colloid (ASC), $^{99m}Tc$-Tin Colloid (TC), $^{99m}Tc$-Human Serum Albumin (HSA), $^{99m}Tc$-Phytate) were performed the particle size by Zeta Sizer (Nano-ZS) and we compared the radiolabeling time, procedure and acquisition time for each of the radiocolloids (total 200 patients). For the last time, we made an analysis of image for each of the radiocolloids with our previous report (SJ Jang et al, Korean Nucl Med Mol imaging Vol.41, No.6, Dec 2007). Results: The particle size of each radiocolloids showed A.S.C (50 nm), T.C (310 nm), H.S.A (10.8 nm), $^{99m}Tc$-Phytate (499 nm). The labeling and acquisition time for each of the radiocolloids showed no substantial difference. But there is difference of the labeling time for the A.S.C. because the ASC procedure need to boiling process. There were no significant differences among those radiocolloids (p>0.005) in the identification rate (IR), false negative rate (FNR), and negative predictive value (NPV). Conclusions: $^{99m}Tc$-labeled radiocolloids showed equivalent results in lymphoscintigraphy. Therefore, in this exam of each radiocolloids could be applied appropriate protocol in lymphoscintigraphy.