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Rapid Scan Electron Paramagnetic Resonance Opens New Avenues for Imaging Physiologically Important Parameters In Vivo
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Comparison of pulse sequences for R1-based electron paramagnetic resonance oxygen imaging
Boris Epel1, Howard J Halpern2
1Department of Radiation and Cellular Oncology, Center for EPR Imaging in Vivo Physiology, The University of Chicago, Chicago, IL 60637, USA; Department of Physics, Kazan Federal University, Kazan 420044, Russia.
Journal of Magnetic Resonance (San Diego, Calif. : 1997)
|April 2, 2015
Summary
Electron paramagnetic resonance (EPR) spin-lattice relaxation (SLR) oxygen imaging accurately measures oxygen levels in live animals. Different EPR protocols suit varying animal sizes, with inversion recovery best for small subjects and other methods for larger ones.
Area of Science:
- Biomedical Engineering
- Medical Physics
- Biophysics
Background:
- Electron paramagnetic resonance (EPR) spin-lattice relaxation (SLR) oxygen imaging is vital for determining oxygen partial pressure in vivo.
- High accuracy, precision, and spatial resolution are key features of EPR oxygen imaging.
- Improving methods for obtaining SLR rates is crucial for biological and medical applications.
Purpose of the Study:
- To compare various pulse EPR imaging protocols and pulse sequences.
- To determine the advantages and applicability of different EPR methods for oxygen imaging.
- To optimize oxygen partial pressure assessment in live animals.
Main Methods:
- Utilized phantoms with spin probes at biologically relevant oxygen concentrations.
- Tested different pulse EPR imaging protocols and pulse sequences.
- Employed filtered backprojection reconstruction for image analysis.
Main Results:
- The inversion recovery sequence with filtered backprojection reconstruction yielded optimal accuracy and precision for small animal imaging.
- Free induction decay and three-pulse stimulated echo sequences showed potential for large animal applications due to lower radio frequency energy deposition.
- Protocol selection is dependent on the size of the animal being imaged.
Conclusions:
- The choice of EPR imaging protocol significantly impacts accuracy and precision based on animal size.
- Inversion recovery is recommended for small animal EPR oxygen imaging.
- Free induction decay and stimulated echo sequences offer practical alternatives for large animals where RF energy deposition is a concern.
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