Localization of inflammation with 111In IgG and 99Tcm albumin colloid labelled leukocytes in a rabbit model

Localization of inflammation with two recently described radiotracers, 111In-labelled polyclonal IgG and 99Tcm albumin colloid labelled leukocytes (Tc-WBC), was studied. Accumulation of activity was compared with 111In-labelled leukocytes (In-WBC) using 131I human serum albumin as a control. Ratios of activity in a chemically induced abscess in the thigh of rabbits compared with normal muscle tissue were measured. The results showed that all agents localize in inflammation but Tc-WBC consistently localizes to a greater degree than the other agents. At 2 h the inflammed-to-normal ratios for Tc-WBC were 4, IgG 2.1, albumin 1.9 and In-WBC 1.7. The pattern of the ratios remained similar over the 18 h period of the study. The short time in which leukocytes can be labelled and the quality of the images obtained suggest that Tc-WBC imaging is the method of choice for this model.