Development of ESR・MRI Dual Imager for Visualization of Reactive Oxygens

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Electron Paramagnetic Resonance Imaging (EPRI) technique has been developed to obtain the spatial distribution of the paramagnetic materials, particularly on a microscopic scale. A large number of biological studies were successfully carried out, especially for the visualization of bio-radicals generated in in vivo system. Typical example is the detection and visualization of nitric oxide (NO) in septic-shocked animals. The strength of EPRI is that only free radicals are visible in its image. On the contrary, weakness of EPRI is that nothing can be visible except paramagnetic materials on its image. Therefore, it seems very hard to obtain in which organs the bioradicals were generated in the small animals. In order to overcome this problem, there are three possible methods to visualize free radicals on the anatomical map of the object. 1: PEDRI (Proton Electron Double Resonance Imaging), 2: conventional MRI, and 3: EPR+MRI system. In this study, we have tried developing EPR/MRI dual imaging system to visualize free radicals on the anatomical map of the object.EPR/MRI dual imaging system was constructed by using the permanent magnet (Nb-Fe-B material) rather than electromagnets or superconductive magnets because it is easier to assemble and combine EPR and MRI components. EPR spectrometer in this dual imaging system is working at 1.2 GHz at 0.04T, and MRI spectrometer in this dual system is working at 22 MHz at 0.5T. The most surprising feature is that the center of MRI magnet is only 20 cm apart from that of EPR magnet. Each spectrometer is working well without any magnetic or electric interference.