title: Application of continuous-wave EPR spectral-spatial image reconstruction techniques for in vivo oxymetry: comparison of projection reconstruction and constant-time modalities.
abstract: In this study we report the application of continuous-wave (CW) electron paramagnetic resonance (EPR) constant-time spectral spatial imaging (CTSSI) for in vivo oxymetry. 2D and 3D SSI studies of a phantom and live mice were carried out using projection reconstruction (PR) and constant-time (CT) modalities using a CW-EPR spectrometer/imager operating at 300 MHz frequency. Distortion of line shape, which is inherent in the PR method, was minimized by the CTSSI modality. It was also found that CTSSI offers improved noise reduction, restores a smoother line shape, and gives high convergence of estimated values. Spatial resolution was also improved by CTSSI, although fundamental spectral line-width broadening was observed. Although additional corrections are required for accurate estimations of spectral line width, CTSSI was able to demonstrate distinct differences in oxygen tension between a tumor and the normal legs of a C3H mouse. The PR method, on the other hand, was unable to make such a distinction unequivocally with the triarylmethyl spin probes. CTSSI promises to be a more suitable method for quantitative in vivo oxymetric studies using radiofrequency EPR imaging (EPRI).
authors.affiliation: Radiation Biology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA.
authors.forename: Ken-ichiro
authors.initials: K
authors.lastname: Matsumoto
authors.forename: Baby
authors.initials: B
authors.lastname: Chandrika
authors.forename: Joost A B
authors.initials: JA
authors.lastname: Lohman
authors.forename: James B
authors.initials: JB
authors.lastname: Mitchell
authors.forename: Murali C
authors.initials: MC
authors.lastname: Krishna
authors.forename: Sankaran
authors.initials: S
authors.lastname: Subramanian
mesh_terms: D000818:Animals; D004578:Electron Spin Resonance Spectroscopy; D005260:Female; D007091:Image Processing, Computer-Assisted; D051379:Mice; D008809:Mice, Inbred C3H; D009374:Neoplasms, Experimental / Q000175:diagnosis*; D010092:Oximetry; D019047:Phantoms, Imaging