Radiolabelling leukocytes with 99Tcm-stannous chloride colloid for the detection of inflammatory lesions

Freshly prepared 99Tcm-stannous chloride colloid (99Tcm-SCC) was used to label human leukocytes. The radiolabelled leukocytes were then injected intravenously into rats bearing carrageenan-induced inflammation in their hindlimbs. Scintigraphic imaging (n = 3) and biodistribution studies (n = 4) 4 h post-injection were performed. The ratio of radioactivity (cpm/pixel) accumulated in the inflammation site to that in the corresponding area of the contralateral limb was 2.9 +/- 0.8, as calculated by region-of-interest analyses of the planar images. The distribution of radioactivity in the dissected tissue showed that the ratio of radioactivity (cpm/g) of infected tissue to that of a normal sample obtained from the contralateral limb was 2.6 +/- 0.5. The biodistribution study of dissected organs showed high uptake in liver (58.9 +/- 8.2%), spleen (4.3 +/- 1.8%) and lungs (6.3 +/- 2.4%). The results of this preliminary study indicate that 99Tcm-SCC can be used as an alternative agent for radiolabelling leukocytes for the detection of inflammatory lesions.