In vivo measurement of partial oxygen pressure in large vessels and in the reticuloendothelial system using fast 19F-MRI

Quantitative in vivo 19F-MRI was performed in a rat model to monitor partial oxygen pressure (pO₂) using a perfluorocarbon (PFC) emulsion as contrast agent. On Days 1, 4, and 8 postin-jection of the PFC emulsion, transaxial T₁ and pO₂ maps were acquired of the abdomen of rats that were consecutively ventilated with pure oxygen, air, and a mixture of 10% oxygen and 90% nitrogen. The images had a resolution of 0.75 mm x 0.75 mm x 2 mm and a total acquisition time of 24 min. In these images it was possible to distinguish between different vessels and hepatic and splenic tissue in the selected imaging plane. Serial 19F-MRI measurements on the different days postinjection of the PFC allowed to determine separately the pO₂ of arterial and venous blood and the intracellular pO₂ in macrophages of the liver and spleen.