Tissue oxygenation: a novel determination using 19F surface coil NMR spectroscopy of sequestered perfluorocarbon...

This work examines the variation with oxygen tension (pO2) of the individual spin-lattice relaxation times (T1) of the 19F resonances of the perfluorocarbon emulsion Oxypherol-ET (FC-43). A linear relationship between 1/T1 and pO2 has been confirmed for all four resonances at any specific temperature. Using a saturation recovery sequence, T1 has been successfully measured using surface coil NMR spectroscopy. This has facilitated measurement of T1 in vivo in a subcutaneous murine tumor. Mice were predosed with Oxypherol-ET emulsion: following complete vascular clearance of the perfluorocarbon, 19F signal was observed specifically from material sequestered in tissue, thus avoiding flow artifacts. Comparison of the pO2 estimated from each of the 19F resonances provided an internal consistency check. A pO2 = 0.1 +/- 2.2% was determined in a Meth-A murine tumor. When the mouse breathed carbogen (95% O2, 5% CO2) no significant change in tumor pO2 was detected, whereas the pO2 in the liver showed a distinct increase.