Localization of technetium-99m-glucarate in zones of acute cerebral injury

Abstract

The potential structural similarity of technetium-99m-labeled glucaric acid (99mTc-glucarate) to that of fructose suggests that this agent may enter cells by a sugar transport system. Studies with LLC-PK1 cells demonstrated inhibition of 99mTc-glucarate uptake by fructose, confirming this potential relationship. Since anaerobic metabolism can use either glucose or fructose, we hypothesized that 99mTc-glucarate may concentrate in areas of acute ischemic injury. To test this hypothesis, 63 adult rats with middle cerebral artery (MCA) occlusion followed by reperfusion were injected with 99mTc-glucarate and in vivo and ex vivo images were acquired. Seven animals were also studied with 18FDG and high resolution PET imaging. The radionuclide images were compared to the results of triphenyl tetrazolium chloride (TTC) staining and conventional histopathology. Thirty-five rats had significant accumulation of 99mTc-glucarate and no TTC staining (indicating infarction) in the involved hemisphere. Of the remaining 28 rats with TTC staining (suggesting viability) of the involved hemisphere, 16 (57%) had 99mTc-glucarate accumulation. In the seven rats that were studied with both 99mTc-glucarate and 18FDG, 99mTc-glucarate accumulated at the center of the occluded MCA territory while 18FDG activity was decreased in this region. These results suggest that 99mTc-glucarate is a sensitive marker of acute severe cerebral injury, but its mechanism of localization is probably different from that of 18FDG.