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Comparison of 250 MHz electron spin echo and continuous wave oxygen EPR imaging methods for in vivo applications
Author(s) -
Epel Boris,
Sundramoorthy Subramanian V.,
Barth Eugene D.,
Mailer Colin,
Halpern Howard J.
Publication year - 2011
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.3555297
Subject(s) - electron paramagnetic resonance , continuous wave , oxygen , nuclear magnetic resonance , in vivo , magnetic resonance imaging , laser linewidth , spin echo , materials science , imaging phantom , voxel , torr , chemistry , biomedical engineering , nuclear medicine , analytical chemistry (journal) , optics , physics , medicine , laser , radiology , microbiology and biotechnology , organic chemistry , chromatography , biology , thermodynamics
Purpose: The authors compare two electron paramagnetic resonance imaging modalities at 250 MHz to determine advantages and disadvantages of those modalities for in vivo oxygen imaging.Methods: Electron spin echo (ESE) and continuous wave (CW) methodologies were used to obtain three‐dimensional images of a narrow linewidth, water soluble, nontoxic oxygen‐sensitive trityl molecule OX063 in vitro and in vivo . The authors also examined sequential images obtained from the same animal injected intravenously with trityl spin probe to determine temporal stability of methodologies.Results: A study of phantoms with different oxygen concentrations revealed a threefold advantage of the ESE methodology in terms of reduced imaging time and more precise oxygen resolution for samples with less than 70 torr oxygen partial pressure. Above ∼ 100 torr , CW performed better. The images produced by both methodologies showed p O 2distributions with similar mean values. However, ESE images demonstrated superior performance in low p O 2regions while missing voxels in high p O 2regions.Conclusions: ESE and CW have different areas of applicability. ESE is superior for hypoxia studies in tumors.