Application of perfluorocarbon emulsions as fluorine-19 nuclear magnetic resonance molecular probes of cardiac tissues oxygen tension
The basic and universal need for oxygen in mammalian tissue has long been recognized. The quantitation of oxygen tension (pO[sub 2]) in cardiac tissue is available by many techniques, but these are generally invasive or superficial. In addition, the role of cardiac pO[sub 2] along the oxygen gradient has yet to be defined. To date, no single method fits the ideal, i.e. non-invasive, sensitive, accurate, rapid, three-dimensional, and economical. The use of perfluorocarbon emulsions as tissue oximeters by [sup 19]F NMR relaxometry has the potential to fulfill many of these requirements. Development of a novel method requires the assessment of validity, reproducibility, and practicality. To this end, I have characterized the linear relationship between pO[sub 2] and the [sup 19]F spin-lattice relaxation rate (R1) for several perfluorocarbon (PFC) emulsions at high magnetic fields. The physical basis of underlying [sup 19]F relaxation mechanisms were modeled with respect to the structure and thermal behavior of perfluorocarbon molecules. Utility of these molecules in vivo was tested by spectroscopy and imaging of perfluorocarbons sequestered in the perfused rat heart. Under a wide range of steady-state oxygenation, the global cardiac tissue pO[sub 2] of perfused rat hearts responded in a manner consistent with physiological processes. The cardiac pO[sub 2] was measured by MRS either with high reproducibility ([plus minus]20 torr) or temporal resolution (1 sec). Independent validation of this method was provided in the total absence of oxygen consumption by the heart. Localized pO[sub 2] measurements in tissue were accomplished by [sup 19]F MRI of PFCs in arrested, perfused rat hearts, and found to change significantly with ischemia. It was concluded that the measurement of pO[sub 2] by NMR can provide important information about the physiological condition of the heart.
- Research Organization:
- Texas Univ., Dallas, TX (United States). Southwestern Medical Center
- OSTI ID:
- 6616632
- Resource Relation:
- Other Information: Thesis (Ph.D.)
- Country of Publication:
- United States
- Language:
- English
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