Abstract
Electron paramagnetic resonance imaging (EPRI) can be used to noninvasively and quantitatively obtain three-dimensional maps of tumor pO₂. The paramagnetic tracer triarylmethyl (TAM), a substituted trityl radical moiety, is not toxic to animals and provides narrow isotropic spectra, which is ideal for in vivo EPR imaging experiments. From the oxygen-induced spectral broadening of TAM, pO₂ maps can be derived using EPRI. The instrumentation consists of an EPRI spectrometer and 7T magnetic resonance imaging (MRI) system both operating at a common radiofrequency of 300 MHz. Anatomic images obtained by MRI can be overlaid with pO₂ maps obtained from EPRI. With imaging times of less than 3 min, it was possible to monitor the dynamics of oxygen changes in tumor and distinguish chronically hypoxic regions from acutely hypoxic regions. In this article, the principles of pO₂ imaging with EPR and some relevant examples of tumor imaging are reviewed.
Publication types
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Research Support, N.I.H., Intramural
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Review
MeSH terms
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Animals
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Benzoates / toxicity
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Cell Hypoxia*
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Electron Spin Resonance Spectroscopy / instrumentation
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Electron Spin Resonance Spectroscopy / methods*
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Glycolysis
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Heterocyclic Compounds, 3-Ring / toxicity
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Humans
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Hypoxia-Inducible Factor 1, alpha Subunit / physiology
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Magnetic Resonance Imaging / instrumentation
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Magnetic Resonance Imaging / methods
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Mice
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Models, Biological
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Neoplasm Proteins / physiology
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Neoplasms / blood supply
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Neoplasms / metabolism
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Neoplasms / pathology*
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Neoplasms / radiotherapy
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Neoplasms, Experimental / blood supply
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Neoplasms, Experimental / metabolism
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Neoplasms, Experimental / pathology
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Neoplasms, Experimental / radiotherapy
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Neovascularization, Pathologic / metabolism
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Neovascularization, Pathologic / physiopathology
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Nuclear Magnetic Resonance, Biomolecular / instrumentation
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Nuclear Magnetic Resonance, Biomolecular / methods
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Oxygen / analysis
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Partial Pressure
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Radiation Tolerance
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Spin Labels
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Trityl Compounds / toxicity
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Tumor Microenvironment
Substances
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Benzoates
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Heterocyclic Compounds, 3-Ring
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Hypoxia-Inducible Factor 1, alpha Subunit
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Neoplasm Proteins
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Spin Labels
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Trityl Compounds
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Oxygen