Development of real-time bioradiographic system for functional and metabolic imaging in living brain tissue.

We have developed a novel imaging system "real-time bioradiography", which is able to estimate the dynamic changes of physiological function and metabolism in living tissues using positron emitter-labeled tracers and chemiluminescence probes. The apparatus is comprised of a photon-counting camera, image-controller, culturing chamber, reflexible solid scintillator and temperature-controlled imaging chamber. The image distribution of radioactivity and chemiluminescence was acquirable with the reflexible solid scintillator and without, respectively. The reflexible solid scintillator is effective to exclude the affect of intra-objective different light reflectivity on radiation detection and to improve the efficiency of radiation detection. To test and to demonstrate the efficacy of this system, we examined the glucose metabolism and superoxide formation during hypoxia-reoxygenation in living brain tissues using 2-[18F]fluoro-2-deoxy-D-glucose (FDG) and Lucigenin, respectively. FDG uptake and chemiluminescence images were obtained at time frames of every 15 min. Glucose metabolism was enhanced during the hypoxic treatment, but the superoxide formation was enhanced during reoxygenation. The enhanced glucose metabolism during hypoxia might cause the increase in superoxide formation during reoxygenation. Thus, this new method would open up possibilities to approach simultaneous biological monitoring of a variety of biochemical events with various combinations of positron emitter-labeled tracers and chemiluminescence probes in living tissues.