Tissue distribution of 203 Pb-acetate: comparison with 67 Ga-citrate as an abscess-localizing agent

Since 203Pb-acetate accumulates in necrotic tumor tissue, the possibility was raised that it might also accumulate in other necrotic tissue such as abscess. We first studied the tissue distribution and excretion of 203Pb-acetate in control rats at 4, 24, 48, 72, and 96 hr. An enterohepatic circulation for lead is suggested. We then compared the uptakes of 203Pb-acetate and 67Ga-citrate in experimental abscesses in rats. The mean gallium accumulation in the abscess was 10 times that of lead at 24 hr and 12 times that of lead at 72 hr. The abscess-to-tissue ratios were greater for gallium for every tissue examined, although the abscessed areas were clearly visualized by scanning at 24 and 72 hr with both agents. With the exception of blood, abscess-to-tissue ratios for 67Ga at 24 hr were higher than or equal to those at 72 hr. However, the 67Ga ratios for the inflamed tissue surrounding the abscess to muscle and blood were higher at 72 hr than at 24 hr, which suggests that inflammation without abscess might be better identified by gallium scanning at 72 hr.