MR imaging of the lung using liquid perfluorocarbons

Area of Science:

• Biomedical Engineering
• Medical Imaging
• Respiratory Physiology

Background:

• Perfluorocarbon (PFC) compounds are utilized as oxygen carriers in blood substitutes due to their inertness and gas solubility.
• The paramagnetic nature of oxygen influences fluorine spin-lattice relaxation times (T1), offering a potential for in vivo oxygen tension (PO2) monitoring.

Purpose of the Study:

• To investigate the magnetic resonance (MR) imaging characteristics of PFC liquids in the lungs.
• To evaluate the effect of oxygenation levels on PFC T1 values and MR signal intensity in vivo.

Main Methods:

• MR imaging of rodent lungs after breathing four different PFC liquids (FC-43, FC-75, PFOB, APF-215).
• Imaging performed at 0.66 T and 0.14 T under ambient air and 100% oxygen breathing conditions.
• In vitro and in vivo measurement of PFC spin-lattice relaxation times (T1) as a function of oxygenation.

Main Results:

• Successful MR imaging of PFC liquids within the lungs of mice and rats was achieved.
• A significant, up to 90%, enhancement in MR image signal strength was observed in vivo when breathing pure oxygen.
• T1 relaxation times of PFCs were found to be dependent on the oxygenation state, both in vitro and in vivo.

Conclusions:

• MR imaging can visualize PFC liquids in the lungs.
• The oxygen-dependent changes in PFC T1 relaxation times and signal intensity provide a basis for non-invasive in vivo PO2 gradient monitoring.
• PFCs demonstrate potential as contrast agents for MR imaging of oxygenation status.