QUANTITATIVE PO2 IMAGING IN-VIVO WITH PERFLUOROCARBON F-19 NMR - TRACKING OXYGEN FROM THE AIRWAY THROUGH THE BLOOD TO ORGAN-TISSUES

The physiological redistribution of perfluorocarbon (PFC) compounds to liver, spleen, bone marrow, and lung after intravenous (IV) or intrap eritoneal CIP) administration of PFC emulsions affords the unique oppo rtunity for non-invasive monitoring of oxygenation status of these org ans and tissues utilizing fluorine (F-19) nuclear magnetic resonance ( NMR) imaging techniques. PFCs also may be introduced directly into the pulmonary airways by procedures such as liquid ventilation, intratrac heal instillation, or aerosol inhalation. Considerations of importance when establishing methodology for accurate quantitation of oxygen par tial pressure (pO(2)) in vivo using F-19 NMR include: 1.) error analys is of the calibration curves which relate pO(2) to the measured PFC F- 19 relaxation rate, 2.) optimization of the NMR pulse sequence for eff icient oxygen sensitive data acquisition and, 3.) fluorine signal inde pendence from emulsion aqueous phase bioconstituents. The porcine mode l was investigated at 0.14T following IV or IP administration of the P FC emulsion containing perfluorotributylamine (FC-43) to demonstate th e capability for tracking oxygen with F-19 NMR from the lung through t he blood to selected organ tissues. Quantitative pO(2) projection imag es and isobaric contour graphs were derived for the liver, spleen, and lungs as a function of inspired oxygen. Blood pO(2) levels in aorta, pulmonary artery, and hepatic vein were monitored simultaneously with NMR imaging for correlative analysis.