Epr Imaging

Eaton, Gareth R.

doi:10.1142/9789812816764_0055

Cited by 14 publications

(21 citation statements)

References 42 publications

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“…It is a powerful method for studying the environment of paramagnetic molecules in live species and provides information about acidity (pH), viscosity, oxygen, and reactive oxygen species concentrations 3 . For heterogeneous samples, ESR spectral information can be obtained in a spatially resolved manner (i.e, by obtaining an image), through the use of magnetic field gradients 4 . This is very similar to the more common method of magnetic resonance imaging (MRI) that mainly observes proton spins.…”

Section: Overview Of Esr Micro-imagingmentioning

confidence: 99%

Electron Spin Resonance Micro-imaging of Live Species for Oxygen Mapping

Halevy

Shtirberg

Shklyar

et al. 2010

JoVE

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This protocol describes an electron spin resonance (ESR) micro-imaging method for three-dimensional mapping of oxygen levels in the immediate environment of live cells with micron-scale resolution 1 . Oxygen is one of the most important molecules in the cycle of life. It serves as the terminal electron acceptor of oxidative phosphorylation in the mitochondria and is used in the production of reactive oxygen species. Measurements of oxygen are important for the study of mitochondrial and metabolic functions, signaling pathways, effects of various stimuli, membrane permeability, and disease differentiation. Oxygen consumption is therefore an informative marker of cellular metabolism, which is broadly applicable to various biological systems from mitochondria to cells to whole organisms. Due to its importance, many methods have been developed for the measurements of oxygen in live systems. Current attempts to provide high-resolution oxygen imaging are based mainly on optical fluorescence and phosphorescence methods that fail to provide satisfactory results as they employ probes with high photo-toxicity and low oxygen sensitivity. ESR, which measures the signal from exogenous paramagnetic probes in the sample, is known to provide very accurate measurements of oxygen concentration. In a typical case, ESR measurements map the probe's lineshape broadening and/or relaxation-time shortening that are linked directly to the local oxygen concentration. (Oxygen is paramagnetic; therefore, when colliding with the exogenous paramagnetic probe, it shortness its relaxation times.) Traditionally, these types of experiments are carried out with low resolution, millimeterscale ESR for small animals imaging. Here we show how ESR imaging can also be carried out in the micron-scale for the examination of small live samples. ESR micro-imaging is a relatively new methodology that enables the acquisition of spatially-resolved ESR signals with a resolution approaching 1 micron at room temperature 2 . The main aim of this protocol-paper is to show how this new method, along with newly developed oxygen-sensitive probes, can be applied to the mapping of oxygen levels in small live samples. A spatial resolution of ~30 x 30 x 100 μm is demonstrated, with near-micromolar oxygen concentration sensitivity and sub-femtomole absolute oxygen sensitivity per voxel. The use of ESR micro-imaging for oxygen mapping near cells complements the currently available techniques based on micro-electrodes or fluorescence/ phosphorescence. Furthermore, with the proper paramagnetic probe, it will also be readily applicable for intracellular oxygen micro-imaging, a capability which other methods find very difficult to achieve. Video LinkThe video component of this article can be found at http://www.jove.com/video/2122/ Protocol Overview of ESR Micro-imagingFirst, we provide a brief explanation of ESR, ESR microscopy, and the various components of our system, and then we will describe the actual imaging experiments.Electron spin resonance is a spectroscopic...

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Section: Overview Of Esr Micro-imagingmentioning

confidence: 99%

Electron Spin Resonance Micro-imaging of Live Species for Oxygen Mapping

Halevy

Shtirberg

Shklyar

et al. 2010

JoVE

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“…45 The technique of CW EPRI has evolved over the past decade to be an important tool in studying distribution of free radicals in many branches of science. [1][2][3][4][5] In the last few years the potential applications of EPRI to studies of living biological systems have been recognized. However, the broad application of the EPRI technique to obtain high quality images of lossy biological samples has been limited by several factors including gradient design and accuracy, sensitivity and speed of acquisition.…”

Section: Epr Spectroscopy Vs Imagingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…[1][2][3][4][5][6] Following the first report by Berliner et al 7,8 on the biological application of EPRI, many applications to studies of living biological systems have been recognized. 3,6 During the last few years significant progress has been made to enable the performance of EPR imaging of biological samples with improved image modality, resolution and quality to obtain useful information. [9][10][11][12][13][14][15][16][17][18] Over the last decade we have focused on developing instrumentation optimized for measurements of free radicals in isolated beating hearts, and in recent several years we have extended our efforts to develop hardware and software to enable spatial and spectral-spatial imaging of free radicals in the heart.…”

Section: Introductionmentioning

confidence: 99%

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Cardiac applications of EPR imaging

Kuppusamy

Zweíer

2004

NMR in Biomedicine

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This review summarizes the development and application of a variety of EPR imaging modalities including spatial, spectral-spatial (spectroscopic), gated-imaging and oxygen mapping to cardiovascular studies. It has been hypothesized that free radical metabolism, oxygenation and nitric oxide generation in biological organs such as the heart may vary over the spatially defined tissue structure. We have developed instrumentation optimized for 3D spatial and 3D or 4D spectral-spatial imaging of free radicals at 1.2 GHz. Using this instrumentation high quality 3D spectral-spatial imaging of nitroxyl (nitroxide) metabolism was performed, as well as spatially localized measurements of oxygen concentrations, based on the oxygen-dependent line-broadening of the EPR spectrum. Both exogenously infused probes and endogenous radicals were used to obtain the images. It is demonstrated that the EPR imaging is a powerful tool which can provide unique information regarding the spatial localization of free radicals, oxygen and nitric oxide in biological organs and tissues.

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“…Electron paramagnetic resonance imaging (EPRI) provides a direct way to detect and map free radicals in a variety of biomedical applications (1)(2)(3)(4)(5)(6)(7)(8) . It can be performed in either pulse mode (time-domain) or continuous wave (CW) mode.…”

Section: Introductionmentioning

confidence: 99%

Fast 3D spatial EPR imaging using spiral magnetic field gradient

Deng

Petryakov

et al. 2007

Journal of Magnetic Resonance

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Electron paramagnetic resonance imaging (EPRI) provides direct detection and mapping of free radicals. The continuous wave (CW) EPRI technique, in particular, has been widely used in a variety of applications in the fields of biology and medicine due to its high sensitivity and applicability to a wide range of free radicals and paramagnetic species. However, the technique requires long image acquisition periods, and this limits its use for many in vivo applications where relatively rapid changes occur in the magnitude and distribution of spins. Therefore, there has been a great need to develop fast EPRI techniques. We report the development of a fast 3D CW EPRI technique using spiral magnetic field gradient. By spiraling the magnetic field gradient and stepping the main magnetic field, this approach acquires a 3D image in one sweep of the main magnetic field, enabling significant reduction of the imaging time. A direct one-stage 3D image reconstruction algorithm, modified for reconstruction of the EPR images from the projections acquired with the spiral magnetic field gradient, was used. We demonstrated using a home-built L-band EPR system that the spiral magnetic field gradient technique enabled a 4 to 7-fold accelerated acquisition of projections. This technique has great potential for in vivo studies of free radicals and their metabolism.

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Epr Imaging

Cited by 14 publications

References 42 publications

Electron Spin Resonance Micro-imaging of Live Species for Oxygen Mapping

Electron Spin Resonance Micro-imaging of Live Species for Oxygen Mapping

Cardiac applications of EPR imaging

Fast 3D spatial EPR imaging using spiral magnetic field gradient

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