Field-cycled proton-electron double-resonance imaging of free radicals in large aqueous samples

Lurie, David John; Hutchison, J.M.S.; Bell, Lawrence H; Nicholson, Ian; Bussell, David M; Mallard, J. R.

doi:10.1016/0022-2364(89)90392-2

Cited by 57 publications

(51 citation statements)

References 4 publications

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“…In the literature, synonyms used to talk about the same method are PEDRI for proton electron double resonance imaging, [199][200][201] or OMRI for Overhauser magnetic resonance imaging. 163,202 The principle is based on the Overhauser effect, and uses a combination of EPR and MRI.…”

Section: Principles Of Dnp Oximetrymentioning

confidence: 99%

“…The use of field-cycled PEDRI overcomes this limitation. 204 The principle is to use an EPR irradiation at low field, meaning low frequency where RF heating is minimal. The field is then increased to a much higher value so that the NMR signals can be measured with improved signal-to-noise ratio, and therefore provide a good image quality.…”

Section: Principles Of Dnp Oximetrymentioning

confidence: 99%

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Assessment of tumor oxygenation by electron paramagnetic resonance: principles and applications

2004

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This review paper attempts to provide an overview of the principles and techniques that are often termed electron paramagnetic resonance (EPR) oximetry. The paper discusses the potential of such methods and illustrates they have been successfully applied to measure oxygen tension, an essential parameter of the tumor microenvironment. To help the reader understand the motivation for carrying out these measurements, the importance of tumor hypoxia is first discussed: the basic issues of why a tumor is hypoxic, why these hypoxic microenvironments promote processes driving malignant progression and why hypoxia dramatically influences the response of tumors to cytotoxic treatments will be explained. The different methods that have been used to estimate the oxygenation in tumors will be reviewed. To introduce the basics of EPR oximetry, the specificity of in vivo EPR will be discussed by comparing this technique with NMR and MRI. The different types of paramagnetic oxygen sensors will be presented, as well as the methods for recording the information (EPR spectroscopy, EPR imaging, dynamic nuclear polarization). Several applications of EPR for characterizing tumor oxygenation will be illustrated, with a special emphasis on pharmacological interventions that modulate the tumor microenvironment. Finally, the challenges for transposing the method into the clinic will also be discussed.

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Section: Principles Of Dnp Oximetrymentioning

confidence: 99%

Section: Principles Of Dnp Oximetrymentioning

confidence: 99%

Assessment of tumor oxygenation by electron paramagnetic resonance: principles and applications

2004

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“…To make PEDRI applicable for in vivo experiments by avoiding excessive sample heating due to high power of EPR irradiation, field cycling (FC) was introduced in the pulse sequence of image acquisition, which greatly reduces the applied field strength during EPR irradiation (82). In FC-PEDRI, the magnetic field applied to the sample is changed throughout the experiment.…”

Section: Field Cyclingmentioning

confidence: 99%

“…Detecting the NMR signals at a high field is necessary to increase the SNR of the experiment. Figure 3 shows FC-PEDRI images of a resolution phantom (B-D); a field-cycled non-PEDRI image (A) is also shown for comparison (82). The center of the phantom consisted of five tubes of internal diameters 15, 9, 5, 4, and 3 mm filled with 2 mM TEMPOL solution.…”

Section: Field Cyclingmentioning

confidence: 99%

In Vivo Application of Proton-Electron Double-Resonance Imaging

Kishimoto

Krishna

Khramtsov

et al. 2018

Antioxidants & Redox Signaling

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Significance: Proton-electron double-resonance imaging (PEDRI) employs electron paramagnetic resonance irradiation with low-field magnetic resonance imaging so that the electron spin polarization is transferred to nearby protons, resulting in higher signals. PEDRI provides information about free radical distribution and, indirectly, about the local microenvironment such as partial pressure of oxygen (pO 2 ), tissue permeability, redox status, and acid-base balance. Recent Advances: Local acid-base balance can be imaged by exploiting the different resonance frequency of radical probes between R and RH + forms. Redox status can also be imaged by using the loss of radical-related signal after reduction. These methods require optimized radical probes and pulse sequences. Critical Issues: High-power radio frequency irradiation is needed for optimum signal enhancement, which may be harmful to living tissue by unwanted heat deposition. Free radical probes differ depending on the purpose of PEDRI. Some probes are less effective for enhancing signal than others, which can reduce image quality. It is so far not possible to image endogenous radicals by PEDRI because low concentrations and broad line widths of the radicals lead to negligible signal enhancement. Future Directions: PEDRI has similarities with electron paramagnetic resonance imaging (EPRI) because both techniques observe the EPR signal, directly in the case of EPRI and indirectly with PEDRI. PEDRI provides information that is vital to research on homeostasis, development of diseases, or treatment responses in vivo. It is expected that the development of new EPR techniques will give insights into novel PEDRI applications and vice versa. Antioxid. Redox Signal. 28, 1345Signal. 28, -1364

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“…This technique has been shown to produce useful functional proton images that can be used to perform non-invasive quantitative in vivo oxymetry, at fields which are two to three orders of magnitude less, compared with standard MRI fields. Sensitivity of OMRI can be additionally improved by field cycling, 13 by which, during the detection of proton signals, the DC field is rapidly ramped up and brought back to a lower field during the saturation of electron. At fields used for OMRI the normal unenhanced MRI will hardly produce any image of significance, although outlines of anatomy may be visible.…”

Section: Introductionmentioning

confidence: 99%

Radio frequency continuous‐wave and time‐domain EPR imaging and Overhauser‐enhanced magnetic resonance imaging of small animals: instrumental developments and comparison of relative merits for functional imaging

et al. 2004

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Electron paramagnetic resonance (EPR) imaging in the continuous wave (CW) and time-domain modes, as well as Overhauser-enhanced magnetic resonance imaging in vivo is described. The review is based mainly on the CW and time-domain EPR instrumentation at 300 MHz developed in our laboratory, and the relative merits of these methods for functional in vivo imaging of small animals to assess hypoxia and tissue redox status are described. Overhauser imaging of small animals at magnetic fields in the range 10-15 mT that is being carried out in our laboratory for tumor imaging and the evaluation of tumor hypoxia based on quantitative evaluation of Overhauser enhancement is also described. Alternate approaches to spectral-spatial imaging using the transverse decay constants to infer in situ line widths and hence in vivo pO 2 using CW and time-domain EPR imaging are also discussed. The nature of the spin probes used, the quality of the images obtained in all the three methods, the achievable resolution, limitations and possible future directions in small animal functional imaging with these modalities are summarized.

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Field-cycled proton-electron double-resonance imaging of free radicals in large aqueous samples

Cited by 57 publications

References 4 publications

Assessment of tumor oxygenation by electron paramagnetic resonance: principles and applications

Assessment of tumor oxygenation by electron paramagnetic resonance: principles and applications

In Vivo Application of Proton-Electron Double-Resonance Imaging

Radio frequency continuous‐wave and time‐domain EPR imaging and Overhauser‐enhanced magnetic resonance imaging of small animals: instrumental developments and comparison of relative merits for functional imaging

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