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Large 30 cm diameter of homogeneous volume EPR imaging magnet system.

Very Low Frequency ERP Imaging In Vivo Physiology

Contents

• Contact Information
• Grant Number
• Research Emphasis
• Current Research
• Resource Capabilities
• References

Contact Information

University of Chicago
Department of Radiation/Cell Oncology
5841 S. Maryland Avenue, MC1105
Chicago, IL 60637
http://rover.bsd.uchicago.edu/lfepr/

Principal Investigator/Contact
Howard J. Halpern, M.D., Ph.D.
University of Chicago
Phone: 773-702-6871
Fax: 772-702-5940
h-halpern@uchicago.edu

Principal Investigator, University of Denver
Gareth Eaton, Ph.D.
Phone: 303-871-2980
Fax: 303-871-2254
geaton@du.edu

Principal Investigator, University of Maryland
Gerald M. Rosen, Ph.D.
Phone: 410-706-0514
Fax: 410-706-8184
grosen@umaryland.edu

Grant Number

Grant No. EB002034

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Research Emphasis

The major aim of this resource is the development of instrumentation, analysis techniques, spin probes and spin traps, and methodologies for imaging physiologically relevant aspects of tissue fluids, including high-resolution oxygen maps, with very low frequency electron paramagnetic resonance imaging (EPRI). Novel bridges and high-access, low-field magnet/gradient systems have produced physiologically relevant measurements and accommodate a number of resonant structures. The resource is a consortium among the University of Chicago, the University of Denver, and the University of Maryland.

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Current Research

In addition to magnets and bridges, the resource has developed spin probes and spin traps to improve sensitivity and resolution of the various tissue functional maps. Novel signal acquisition methods will improve signal-to-noise of EPRI. Image acquisition strategies will optimize and reduce the time of information acquisition. Continuous wave and pulsed EPR bridges will be used to develop general rules governing situations where each is optimum. Dendrimer-containing nitronyl nitrones will increase the sensitivity of the spin trapping technique. Collaborative research includes work with MRI to evaluate physiologic response to anti-angiogenic agents and radiation, exploring tissue responses to tumor oxygenating agents, to understand, using oxygen images, the relationship between tumor pO₂ radiobiologic hypoxia, and the measurement of frequency-dependence of the ability to measure electron-nuclear distances and of electron spin relaxation times.

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Resource Capabilities

Three low-frequency imagers include:

• A low-frequency imaging spectrometer, with a magnet sufficiently versatile to accommodate both birdcage and loop-gap resonant structures and varied animal and organ preparations of diameters up to 5 cm, available at the University of Chicago.
• A low-frequency imager with a pulsed bridge, available at the University of Denver.
• A similar continuous wave and pulsed imager at the University of Chicago capable of accommodating samples of diameter of up to 10 cm and a larger, 20 cm bore imager, available in 2005 with a pulsed bridge capability allowing EPR imaging at frequencies of 100 to 300 MHz.

The resource has developed and will provide expertise in the fabrication of novel EPR resonators. The resource has synthesized novel spin probes and spin traps, and developed novel imaging strategies developed to exploit this novel front-end imaging modality. Test equipment for the assessment of components operating at the above frequencies is available, as is animal monitoring equipment for correlation with resource images.

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References

1. Elas M, Williams BB, Parasca A, Mailer C, Pelizzari CA, Lewis MA, River JA, Karczmar GS, Barth E, Halpern HJ. Quantitative tumor oxymetric images from 4-dimensional electron paramagnetic resonance imaging (EPRI): methodology and comparison with blood oxygen level dependent (BOLD) MRI Magn Reson Med 2003;49:582-591.
2. Quine RW, Rinard GA, Eaton SS, Eaton GR. A pulsed and continuous wave 250 MHz electron paramagnetic resonance spectrometer. Concepts Magn Reson Magn Reson Engin 2002;1:59-91.
3. Rosen GM, Porasuphatana S, Tsai P, Ambulos, Galtsev VE, Halpern HJ. Dendrimeric-containing nitronyl nitroxides as spin traps for nitric oxide: synthesis, kinetic and stability studies. Macromolecules 2003;36:1021-1027.