In Vivo Measurements of Vascular Oxygen Tension in Tumors Using MRI of a Fluorinated Blood Substitute

Abstract

The authors measured the level of blood oxygenation in vivo in a series of rats with implanted mammary adenocarcinoma. The technique used was ¹⁹F magnetic resonance imaging of a perfluorochemical blood substitute. The method is based on the effect of oxygen on the T1 relaxation time of the fluorochemical and allows the determination of mean vascular PO₂ independent of the blood volume in the tissue. The PO₂ levels in the liver, lung, and spleen also were determined and were consistent with previously reported results. When the rats breathed air, the tumor PO₂ levels were somewhat lower than in the other organs and were in a range typical of venous blood. When the rat was given 100% oxygen to breathe, the tumor PO₂ levels increased far less than the PO₂ levels of the other organs. This may indicate a greatly diminished blood flow to this particular tumor.