Measurement of individual organ tissue
oxygen levels can provide information to help evaluate and optimize medical interventions in many areas including wound healing,
resuscitation strategies, and
cancer therapeutics. Echo planar (19) F MRI has previously focused on
tumor oxygen measurement at low
oxygen levels (pO(2)) <30 mmHg. It uses the linear relationship between spin-lattice relaxation rate (R(1)) of
hexafluorobenzene (HFB) and pO(2). The feasibility of this technique for a wider range of pO(2) values and individual organ tissue pO(2) measurement was investigated in a rat model. Spin-lattice relaxation times (T(1) = 1/R(1)) of
hexafluorobenzene were measured using (19) F saturation recovery echo planar imaging. Initial in vitro studies validated the linear relationship between R(1) and pO(2) from 0 to 760 mmHg
oxygen partial pressure at 25, 37, and 41°C at 7 Tesla for
hexafluorobenzene. In vivo experiments measured rat tissue
oxygen (
ptO2) levels of brain, kidney, liver, gut, muscle, and skin during inhalation of both 30 and 100%
oxygen. All organ ptO(2) values significantly increased with
hyperoxia (P < 0.001). This study demonstrates that (19) F MRI of
hexafluorobenzene offers a feasible tool to measure regional
ptO2 in vivo, and that
hyperoxia significantly increases
ptO2 of multiple organs in a rat model.