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In vivo mapping of tumor oxygen consumption using 19 F MRI relaxometry
Author(s) -
Diepart Caroline,
Magat Julie,
Jordan Bénédicte F.,
Gallez Bernard
Publication year - 2011
Publication title -
nmr in biomedicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.278
H-Index - 114
eISSN - 1099-1492
pISSN - 0952-3480
DOI - 10.1002/nbm.1604
Subject(s) - oxygen , in vivo , electron paramagnetic resonance , chemistry , relaxometry , magnetic resonance imaging , nuclear magnetic resonance , oxygen saturation , kinetics , nuclear medicine , analytical chemistry (journal) , medicine , spin echo , biology , radiology , chromatography , physics , microbiology and biotechnology , organic chemistry , quantum mechanics
Recently, we have developed a new electron paramagnetic resonance (EPR) protocol in order to estimate tissue oxygen consumption in vivo . Because it is crucial to probe the heterogeneity of response in tumors, the aim of this study was to apply our protocol, together with 19 F MRI relaxometry, to the mapping of the oxygen consumption in tumors. The protocol includes the continuous measurement of tumor p O 2 during the following respiratory challenge: (i) basal values during air breathing; (ii) increasing p O 2 values during carbogen breathing until saturation of tissue with oxygen; (iii) switching back to air breathing. We have demonstrated previously using EPR oximetry that the kinetics of return to the basal value after oxygen saturation are mainly governed by tissue oxygen consumption. This challenge was applied in hyperthyroid mice (generated by chronic treatment with L ‐thyroxine) and control mice, as hyperthyroidism is known to dramatically affect the oxygen consumption rate of tumor cells. Our recently developed snapshot inversion recovery MRI fluorocarbon oximetry technique allowed the p O 2 return kinetics to be measured with a high temporal resolution. The kinetic constants (i.e. oxygen consumption rates) were higher for tumors from hyperthyroid mice than from control mice, data that are consistent with our previous EPR study. The corresponding histograms of the 19 F MRI data showed that the kinetic constants displayed a shift to the right for the hyperthyroid group, indicating a higher oxygen consumption in these tumors. The color maps showed a large heterogeneity in terms of oxygen consumption rate within a tumor. In conclusion, 19 F MRI relaxometry allows the noninvasive mapping of the oxygen consumption in tumors. The ability to assess the heterogeneity of tumor response is critical in order to identify potential tumor regions that might be resistant to treatment and therefore produce a poor response to therapy. Copyright © 2010 John Wiley & Sons, Ltd.