The purpose of the present investigation was to evaluate the feasibility of imaging inflammatory lesions with some small molecular weight complexes of Tc-99m with renal excretion in comparison to Tc-99m-dextran (D), Tc-99m-HIG and Ga-67-citrate. The biodistributions of pertechnetate (P), Tc-99m-citrate (Cit), -gluconate (G), -glucoheptonate (GH), -DTPA, -glucose phosphate (GP), -D, -HIG and Ga-67-Cit were determined in mice with turpentine-induced abscesses at 1, 3, 6 and 24 h after i.v. injection of 15 MBq. % uptake/g tissues and abscess/muscle (A/M), blood (A/B), liver (A/L), intestine (A/I) and kidney (A/K) concentration ratios were calculated. The scintigraphic images of all mice were obtained by a gamma-camera. The abscesses were well visualized with all the radiopharmaceuticals (RPs). The excretion was mainly via the kidneys except for Tc-99m-D, Tc-99m-HIG and Ga-67-Cit. They showed Variable amounts of liver and kidney uptake. Similar A/M ratios were obtained with all the RPs, reaching max. at 3 h with pertechnetate, Tc-99m-Cit and Tc-99m-GP, at 6 h with Tc-99m-DTPA and at 24 h with Tc-99m-G, Tc-99m-GH, Tc-99m-D and Tc-99m-HIG. The max. A/M ratios were 3.61 +/- 1.63, 4.61 +/- 3.92, 5.21 +/- 1.24, 3.60 +/- 0.52, 3.43 +/- 0.92, 5.37 +/- 0.67, 5.98 +/- 1.17 and 4.76 +/- 2.03 for Tc-99m-P, -Cit, -G, -GH, -DTPA, -D, -HIG and Ga-67-Cit, respectively. Our results indicated that small molecular weight complexes of Te-99m can be used in imaging inflammation as well as high molecular weight complexes such as (TC)-T-99m-D, (TC)-T-99m-HIG and Ga-67-Cit. However, the first group is preferred, because of rapid blood clearance and excretion predominantly via the kidneys, which is an advantage for the identification of abdominal abscesses. The main mechanism of accumulation of all the RPs might be a simple diffusion process through the injured capillaries. An additional mechanism of binding to proteins was considered in view of the increasing concentration ratios with Tc-99m-G, -GH, -D and -HIG as time progressed.
