Tissue oxygenation: A novel determination using ¹⁹F surface coil NMR spectroscopy of sequestered perfluorocarbon emulsion

This work examines the variation with oxygen tension (pO₂) of the individual spin‐lattice relaxation times (T_I) of the ¹⁹F resonances of the perfluorocarbon emulsion Oxy‐pherol‐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 T_I in vivo in a subcutaneous murine tumor. Mice were predosed with Oxypherol‐ET emulsion; following complete vascular clearance of the pertluorocarbon, 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. © 1991 Academic Press. Inc.