Development of separable electron spin resonance-computed tomography imaging for multiple radical species: An application to center dot OH and centerdot NO

A method of separable ESR-CT (electron spin resonance-computed tomography) imaging for multiple radical species was developed and applied to imaging o f OH and NO. The algorithm was improved by combining filtered back-projecti on with a modified algebraic reconstruction technique to enhance accuracy a nd shorten calculation time. With this algorithm, spectral-spatial images o f the phantom consisting of 3-carbamoyl-2,2,5,5,-tetramethylpyrrolidine-N-o xyl and 2-phenyl-4,4,5,5,-tetramethylimidazoline-3-oxide-1-oxyl could be ob tained in different directions by rotating the spatial axis. The spatial fu nction of individual radicals was extracted by each of the two methods from each spectral-spatial image. The separative 2D images of each radical were individually constructed using the spatial function obtained with the two methods. By comparing the separative images with the phantom sample, the al gorithm for separable ESR-CT imaging was established. This ESR-CT technique was combined with L-band ESR spectroscopy and applied to the separative im aging of OH and NO, which were spin trapped with 5,5-dimethyl-1-pyrroline-N -oxide (DMPO) and Fe2+-N-methyl-D-glucamine dithiocarbamate complex, respec tively. The ESR signal of DMPO-OH decreased gradually during data acquisiti on, and the decrease was calibrated by extrapolating the signal intensity t o the beginning of data sampling. Both the position and size of the individ ual images for OH and NO were in very good agreement with the findings for the sample.