title: Comparison of pulse sequences for R1-based electron paramagnetic resonance oxygen imaging.
abstract: Electron paramagnetic resonance (EPR) spin-lattice relaxation (SLR) oxygen imaging has proven to be an indispensable tool for assessing oxygen partial pressure in live animals. EPR oxygen images show remarkable oxygen accuracy when combined with high precision and spatial resolution. Developing more effective means for obtaining SLR rates is of great practical, biological and medical importance. In this work we compared different pulse EPR imaging protocols and pulse sequences to establish advantages and areas of applicability for each method. Tests were performed using phantoms containing spin probes with oxygen concentrations relevant to in vivo oxymetry. We have found that for small animal size objects the inversion recovery sequence combined with the filtered backprojection reconstruction method delivers the best accuracy and precision. For large animals, in which large radio frequency energy deposition might be critical, free induction decay and three pulse stimulated echo sequences might find better practical usage.
authors.affiliation: Department of Radiation and Cellular Oncology, Center for EPR Imaging in Vivo Physiology, The University of Chicago, Chicago, IL 60637, USA; Department of Physics, Kazan Federal University, Kazan 420044, Russia. Electronic address: bepel@uchicago.edu.
authors.forename: Boris
authors.initials: B
authors.lastname: Epel
authors.affiliation: Department of Radiation and Cellular Oncology, Center for EPR Imaging in Vivo Physiology, The University of Chicago, Chicago, IL 60637, USA. Electronic address: h-halpern@uchicago.edu.
authors.forename: Howard J
authors.initials: HJ
authors.lastname: Halpern
mesh_terms: D000818:Animals; D003952:Diagnostic Imaging / Q000295:instrumentation / Q000379:methods*; D004578:Electron Spin Resonance Spectroscopy / Q000295:instrumentation / Q000379:methods*; D007091:Image Processing, Computer-Assisted; D010084:Oxidation-Reduction; D010092:Oximetry; D010100:Oxygen / Q000737:chemistry*; D019047:Phantoms, Imaging
chemical_list: D010100:Oxygen
keywords: EPR; Imaging; Oxygen; Pulse sequence; Relaxation
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