High Spatial Resolution Multi-Site EPR Oximetry

Grinberg, Oleg Y.; Smirnov, Alex I.; Swartz, Harold M.

doi:10.1006/jmre.2001.2408

Cited by 18 publications

(14 citation statements)

References 28 publications

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“…EPR oximetry, first reported by Hyde [1] and later extensively investigated by Swartz and colleagues [2][3][4][5], enables repeated measurements of oxygen concentrations in living tissues. In vivo oximetry [6][7][8][9] is the measurement of partial pressure of oxygen (pO 2 ) by observing oxygen-induced broadening in the lineshape of an introduced paramagnetic probe.…”

Section: Epr Oximetrymentioning

confidence: 99%

EPR oximetry in three spatial dimensions using sparse spin distribution

Som

Potter

Ahmad

et al. 2008

Journal of Magnetic Resonance

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A method is presented to use continuous wave electron paramagnetic resonance imaging for rapid measurement of oxygen partial pressure in three spatial dimensions. A particulate paramagnetic probe is employed to create a sparse distribution of spins in a volume of interest. Information encoding location and spectral linewidth is collected by varying the spatial orientation and strength of an applied magnetic gradient field. Data processing exploits the spatial sparseness of spins to detect voxels with nonzero spin and to estimate the spectral linewidth for those voxels. The parsimonious representation of spin locations and linewidths permits an order of magnitude reduction in data acquisition time, compared to four-dimensional tomographic reconstruction using traditional spectral-spatial imaging. The proposed oximetry method is experimentally demonstrated for a lithium octa-n-butoxy naphthalocyanine (LiNc-BuO) probe using an L-band EPR spectrometer.

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Section: Epr Oximetrymentioning

confidence: 99%

EPR oximetry in three spatial dimensions using sparse spin distribution

Som

Potter

Ahmad

et al. 2008

Journal of Magnetic Resonance

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“…A magnetic field gradient was applied in the same direction to obtain maximum separation of the EPR signals from different capillaries. Following the algorithm, theoretical simulations, and experimental validations shown earlier [4], two spectra were taken at two different magnitudes of the gradient in the same direction. If the first EPR spectrum, which we will call experimental, was recorded at a smaller gradient GI over a spectral window AB~, then the second spectrum, which we will call envelope, should be recorded at a larger gradient G 2 over a proportionally larger spectral window AB z = AB~.…”

Section: Data Acquisition and Processingmentioning

confidence: 99%

“…EPR oximetry with particulates involves implantation of an oxygen-sensitive material a few days in advance, allowing the tissue to heal and then making all the measurements from the surface. To monitor tissue pO 2 simultaneously at severat points, we have developed several approaches which we call multisite (MS) EPR oximetry [3,4]. Our most accurate method of high-spatial-resolution MS EPR oximetry is based on consecutive applications of magnetic field gradients with the same direction but different magnitudes.…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, it could be called also two-gradient convolution EPR oximetry. While the general outline of this method has been described previously [4], there remains a need to describe the experimental limitations of the method, especially in practical applications, and then to develop methods to reduce these limitations.…”

Section: Introductionmentioning

confidence: 99%

“…New user-friendly Windows-based software has been developed using the same algorithm as we described previously [4]. This software allows one to analyze spectra more promptly in an automatic manner, thus eliminating some manual inputs that were needed in the previous software (the new software can be downloaded from the web page www.grinberg.net/-olg/).…”

Section: Introductionmentioning

confidence: 99%

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Practical conditions and limitations for high-spatial-resolution multisite EPR oximetry

Grinberg¹,

Smirnov

Grinberg

et al. 2005

Appl. Magn. Reson.

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We have previously reported a high-spatial-resolution multisite electron paramagnetic resonance (EPR) oximetry method that is based on consecutive applications of magnetic field gradients with the same direction but different magnitudes. This method that could be called also two-gradient convolution EPR oximetry has no restrictions for the shape of sotid paramagnetic mate¡ implanted in tissue and is applicable for any particulate EPR oxygen-sensitive material with a Lorentzian line shape. To enhance the utilization of this method, a previously described algorithm was used to develop user-f¡ Windows-based software. Practical conditions of application of the method were established using several different model systems. It has been shown that the spectral overlap from the adjacent sites can be negleeted if the splitting between the corresponding lines exceeds the largest line width by at least a factor of 1.3. Ah additional requirement of the method is that the second field gradient should exceed by at least 30% the value of the first gradient. It was confirmed that the error in line width determination at L-band is proportional to the noise-to-signal ratio, and does not exceed 1% a noise-to-signal ratio of 0.1 in a typical in vivo experiment. We demonstrate that the line widths of up to 10 different sites can be determined.

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Clinical applications of EPR: overview and perspectives

et al. 2004

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The development and use of in vivo techniques for strictly experimental applications in animals has been very successful, and these results now have made possible some very attractive potential clinical applications. The area with the most obvious immediate, effective and widespread clinical use is oximetry, where EPR almost uniquely can make repeated and accurate measurements of pO 2 in tissues. Such measurements can provide clinicians with information that can impact directly on diagnosis and therapy, especially for oncology, peripheral vascular disease and wound healing. The other area of immediate and timely importance is the unique ability of in vivo EPR to measure clinically significant exposures to ionizing radiation 'after-the-fact', such as may occur due to accidents, terrorism or nuclear war. There are a number of other capabilities of in vivo EPR that also potentially could become extensively used in human subjects. In pharmacology the unique capabilities of in vivo EPR to detect and characterize free radicals could be applied to measure free radical intermediates from drugs and oxidative process. A closely related area of potential widespread applications is the use of EPR to measure nitric oxide. These often unique capabilities, combined with the sensitivity of EPR spectra to the immediate environment (e.g. pH, molecular motion, charge) have already resulted in some very productive applications in animals and these are likely to expand substantially in the near future. They should provide a continually developing base for extending clinical uses of in vivo EPR. The challenges for achieving full implementation include adapting the spectrometer for safe and comfortable measurements in human subjects, achieving sufficient sensitivity for measurements at the sites of the pathophysiological processes that are being measured, and establishing a consensus on the clinical value of the measurements.

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High Spatial Resolution Multi-Site EPR Oximetry

Cited by 18 publications

References 28 publications

EPR oximetry in three spatial dimensions using sparse spin distribution

EPR oximetry in three spatial dimensions using sparse spin distribution

Practical conditions and limitations for high-spatial-resolution multisite EPR oximetry

Clinical applications of EPR: overview and perspectives

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