EPR zeugmatography with modulated magnetic field gradient

Herrling, T.; Klimes, N.; Karthe, W.; Ewert, Uwe; Ebert, Bernd

doi:10.1016/0730-725x(84)90162-0

Cited by 6 publications

(7 citation statements)

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“…The concept that underlies the MFG method is to measure the undistorted magnetic resonance signals from areas where no MFG is present (6–8). The signals from the rest of the region are not detected due to overmodulation of the field gradient.…”

Section: Methodsmentioning

confidence: 99%

“…Instead, a 3D image can be assembled by collecting m slices of n 2D projection data, which results in a considerably decreased imaging time. The modulated magnetic field gradient (MFG) method (6–8) in combination with continuous wave (CW) EPR imaging can be used to obtain multislice images of free radicals in mice for the first time within a limited time that has not been achieved previously. This slice‐selective imaging method should contribute to various biomedical studies of disease in animal models involving ROS.…”

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confidence: 99%

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Slice‐selective images of free radicals in mice with modulated field gradient electron paramagnetic resonance (EPR) imaging

Sato-Akaba

Abe

Fujii

et al. 2008

Magnetic Resonance in Med

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Continuous wave (CW) electron paramagnetic resonance (EPR) imaging can be used to obtain slice-selective images of free radicals without measuring three-dimensional (3D) projection data. A method that incorporated a modulated magnetic field gradient (MFG) was combined with polar field gradients to select a slice in the subject noninvasively. The slice-selective in vivo EPR imaging of triarylmethyl radicals in the heads of live mice is reported. 3D surface-rendered images were successfully obtained from slice-selective images. In the experiment in mice, a slice thickness of 1. Reactive oxygen species (ROS) such as superoxides and hydroxyl radicals play a key role in pathophysiological processes and cell damage (1,2). To investigate the physiological functions of ROS in mice or rats noninvasively, an imaging method that could provide three-dimensional (3D) or multislice images of free radicals would be valuable. Electron paramagnetic resonance (EPR) techniques can be used for the noninvasive imaging of paramagnetic species such as free radicals (3-5). Usually, pixel-or voxelbased information is obtained by measuring 3D projection data. However, this process is time-consuming since n 2 projections are necessary for 3D images, instead of n projections for 2D images. However, there is no practical method that can provide 2D slice-selective EPR images in vivo. In this study, we demonstrate slice-selective in vivo EPR imaging in living mice while avoiding the need to collect n 2 projection data that are required for 3D imaging. Instead, a 3D image can be assembled by collecting m slices of n 2D projection data, which results in a considerably decreased imaging time. The modulated magnetic field gradient (MFG) method (6 -8) in combination with continuous wave (CW) EPR imaging can be used to obtain multislice images of free radicals in mice for the first time within a limited time that has not been achieved previously. This slice-selective imaging method should contribute to various biomedical studies of disease in animal models involving ROS. However, direct detection of ROS in vivo is a challenge in animal imaging not only with this method but also with other EPR imaging techniques. Therefore, the generation of ROS has been studied through reduction/oxidation reactions that can be measured from the decay of exogenously infused spin probes (9 -11).One of the most challenging problems for in vivo EPR imaging is to reduce the time needed to acquire the projection data that are necessary for image reconstruction. While pulsed EPR imaging can be used to acquire projection data rapidly (12), it is technically difficult to detect free radical molecules that have a short relaxation time. For example, it is challenging to measure nitroxide spin probes and iron-complex adducts of nitric oxide with pulsed imaging, whereas CW-EPR imaging can detect these species with adequate sensitivity (13). In this study, we adopt for the first time an approach used in EPR microscopy of paramagnetic crystals in the X-band (9 GHz) of slice-selec...

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Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

Slice‐selective images of free radicals in mice with modulated field gradient electron paramagnetic resonance (EPR) imaging

Sato-Akaba

Abe

Fujii

et al. 2008

Magnetic Resonance in Med

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“…Figure 3 shows how the distance of the maximum as a multiple of the sampling width depends upon the quotient of the apparent width and the sampling width. Thus the position of the maximum with respect to the true zero can be determined graphically or from the polynomial y = -0.0615 + 0.374d -0.0514d2 + 0.00254d3 (19) A graph of In c against the square of the distance, x, from the true zero gives the corrected gradient; see Eqn On re-examining our previously published data' ' we find that the correction of 7 mm used for the three sets of data was appropriate, the new corrections reported here being 7.0, 7.6 and 7.8 mm in order of increasing diffusion times. It should be noted that the error incurred by using the single value of 7 mm is less than 2 Yo.…”

Section: Corrected-zero Methodsmentioning

confidence: 99%

“…Wb by W, and use the polynomial given in Eqn (19) to determine the position of the maximum from the zero distance as a fraction, of the sampling width. 5.…”

Section: Dividementioning

confidence: 99%

ESR measurement of translational diffusion constants

Fawthrop

Gillies

Sutcliffe

et al. 1995

Magnetic Reson in Chemistry

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ESR spectroscopy can be used to measure the translational diffusion constants of spin probes in a variety of media using a capillary method. Following preliminary work, it has been possible to improve upon the accuracy of determining diffusion constants in two ways. Both methods require an experimental measurement of the resonant cavity sampling profile. In the first procedure, this cavity profile is convolved with a trial Gaussian distribution and the result is compared with the experimental data obtained from the ESR measurements; the diffusion constant is then determined by graphical optimization. The second method is a graphical one based on a knowledge of the experimental diffusion profile and the cavity sampling profile. Both methods have been shown to give similar results but the second less rigorous corrected-zero method is generally simpler to apply. For a medium such as water, it takes several days to acquire the necessary experimental data but the time taken to carry out the experiment can be shortened (or slower rates of diffusion can be measured) by using a shielded resonant cavity.

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“…As a new method, the field gradient was modulated at a certain frequency (Herrling et al 1982, Ewert and Herding 1986a, b, 1989. ENDOR imaging was also studied for spin labeled compounds (Janzen and Kotake 1986).…”

Section: Introductionmentioning

confidence: 99%

ESR Microscopy: Scanning ESR Imaging of Spin Density

Ikeya¹

1993

New Applications of Electron Spin Resonance

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EPR zeugmatography with modulated magnetic field gradient

Cited by 6 publications

References 0 publications

Slice‐selective images of free radicals in mice with modulated field gradient electron paramagnetic resonance (EPR) imaging

Slice‐selective images of free radicals in mice with modulated field gradient electron paramagnetic resonance (EPR) imaging

ESR measurement of translational diffusion constants

ESR Microscopy: Scanning ESR Imaging of Spin Density

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