Premium
Absolute oxygen R 1e imaging in vivo with pulse electron paramagnetic resonance
Author(s) -
Epel Boris,
Bowman Michael K.,
Mailer Colin,
Halpern Howard J.
Publication year - 2014
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.24926
Subject(s) - electron paramagnetic resonance , magnetic resonance imaging , nuclear magnetic resonance , relaxation (psychology) , in vivo , oxygen , unpaired electron , pulsed epr , pulse (music) , chemistry , partial pressure , materials science , biophysics , biomedical engineering , medicine , spin echo , biology , physics , radiology , optics , microbiology and biotechnology , organic chemistry , detector
Purpose Tissue oxygen (O 2 ) levels are among the most important and most quantifiable stimuli to which cells and tissues respond through inducible signaling pathways. Tumor O 2 levels are major determinants of the response to cancer therapy. Developing more accurate measurements and images of tissue O 2 partial pressure (pO 2 ), assumes enormous practical, biological, and medical importance. Methods We present a fundamentally new technique to image pO 2 in tumors and tissues with pulse electron paramagnetic resonance (EPR) imaging enabled by an injected, nontoxic, triaryl methyl (trityl) spin probe whose unpaired electron's slow relaxation rates report the tissue pO 2 . Heretofore, virtually all in vivo EPR O 2 imaging measures pO 2 with the transverse electron spin relaxation rate, R 2e , which is susceptible to the self‐relaxation confounding O 2 sensitivity. Results We found that the trityl electron longitudinal relaxation rate, R 1e , is an order of magnitude less sensitive to confounding self‐relaxation. R 1e imaging has greater accuracy and brings EPR O 2 images to an absolute pO 2 image, within uncertainties. Conclusion R 1e imaging more accurately determines oxygenation of cancer and normal tissue in animal models than has been available. It will enable enhanced, rapid, noninvasive O 2 images for understanding oxygen biology and the relationship of oxygenation patterns to therapy outcome in living animal systems. Magn Reson Med 72:362–368, 2014. © 2013 Wiley Periodicals, Inc.