Rapid Scan Electron Paramagnetic Resonance Opens New Avenues for Imaging Physiologically Important Parameters &lt;em&gt;In Vivo&lt;/em&gt;

Biller, Joshua R.; Mitchell, David; Tseytlin, Mark; Elajaili, Hanan; Rinard, George A.; Quine, Richard W.

doi:10.3791/54068

Cited by 7 publications

(6 citation statements)

References 33 publications

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“…Additionally, RS has been performed via frequency sweeps using a static magnetic field, shifting the RS capabilities from the coil driver to the frequency generator [ 92 , 93 ]. This technique is particularly enticing for low-field applications where high-resolution frequency sweeps may be possible with the current generation of commercially available arbitrary waveform generators (AWGs) and in non-resonant applications where considerations of bandwidth in relation to resonator Q are no longer necessary [ 94 ].…”

Section: What Information Could We Use In the Low Field?mentioning

confidence: 99%

EPR Everywhere

Biller

McPeak

2021

Appl Magn Reson

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This review is inspired by the contributions from the University of Denver group to low-field EPR, in honor of Professor Gareth Eaton's 80th birthday. The goal is to capture the spirit of innovation behind the body of work, especially as it pertains to development of new EPR techniques. The spirit of the DU EPR laboratory is one that never sought to limit what an EPR experiment could be, or how it could be applied. The most well-known example of this is the development and recent commercialization of rapid-scan EPR. Both of the Eatons have made it a point to remain knowledgeable on the newest developments in electronics and instrument design. To that end, our review touches on the use of miniaturized electronics and applications of single-board spectrometers based on software-defined radio (SDR) implementations and single-chip voltage-controlled oscillator (VCO) arrays. We also highlight several non-traditional approaches to the EPR experiment such as an EPR spectrometer with a "wand" form factor for analysis of the OxyChip, the EPR-MOUSE which enables non-destructive in situ analysis of many non-conforming samples, and interferometric EPR and frequency swept EPR as alternatives to classical high Q resonant structures.

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Section: What Information Could We Use In the Low Field?mentioning

confidence: 99%

EPR Everywhere

Biller

McPeak

2021

Appl Magn Reson

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“…The majority of low frequency EPR spectrometers operate at about 1 GHz, which provides a good compromise between detection sensitivity and depth of microwave penetration 64. However, a few laboratories have successfully used spectrometers operating around 250 MHz for in vivo EPR experiments 676970. Moreover, the first custom-designed clinical EPR spectrometer for human study was built at Dartmouth Medical School, Hanover, NH, USA and the initial results have since been reported 7172…”

Section: Instrumentation For In Vivo Epr Oximetry Studiesmentioning

confidence: 99%

“…While, 3D spectral-spatial oximetry imaging has been demonstrated in isolated rat heart21101 and tumor oxygenation studies,102103 3D spectral-spatial imaging is still challenging using commercially available EPR spectrometers due to poor image resolution and long acquisition times of several hours or more. However, recent developments in pulse and rapid scan techniques for EPR and EPRI have the potential to greatly reduce acquisition time and improvements in SNR ratio per unit time compared to more common EPR methods 67697099104105. With future developments in rapid-scan techniques, fast magnetic field gradients and pulsed EPR methods, advancements in 3D functional EPR imaging may be feasible.…”

Section: Epr Oximetry Probes and Applications In Brain Researchmentioning

confidence: 99%

“…However, recent developments in pulse and rapid scan techniques for EPR and EPRI have the potential to greatly reduce acquisition time and improvements in SNR ratio per unit time compared to more common EPR methods. 67 69 70 99 104 105 With future developments in rapid-scan techniques, fast magnetic field gradients and pulsed EPR methods, advancements in 3D functional EPR imaging may be feasible. Another potential shortcoming of EPRI is the fact that it does not provide any anatomical information, but efforts are underway to improve methods for co-registration of EPRI with MRI.…”

Section: Epr O Ximetry P Robes and mentioning

confidence: 99%

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In vivo electron paramagnetic resonance oximetry and applications in the brain

Weaver

Liu

2017

Med Gas Res

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Molecular oxygen (O2) is essential to brain function and mechanisms necessary to regulate variations in delivery or utilization of O2 are crucial to support normal brain homeostasis, physiology and energy metabolism. Any imbalance in cerebral tissue partial pressure of O2 (pO2) levels may lead to pathophysiological complications including increased reactive O2 species generation leading to oxidative stress when tissue O2 level is too high or too low. Accordingly, the need for oximetry methods, which assess cerebral pO2 in vivo and in real time, is imperative to understand the role of O2 in various metabolic and disease states, including the effects of treatment and therapy options. In this review, we provide a brief overview of the common in vivo oximetry methodologies for measuring cerebral pO2. We discuss the advantages and limitations of oximetry methodologies to measure cerebral pO2 in vivo followed by a more in-depth review of electron paramagnetic resonance oximetry spectroscopy and imaging using several examples of current electron paramagnetic resonance oximetry applications in the brain.

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“…Fast scans that span over wide EPR spectra can be produced [8]. The rapid scan (RS) EPR method of generating and processing transient responses to the sinusoidal magnetic field stimulus was quite a success, producing a multitude of publications [9–25], a patent application [26], and commercialization by Bruker BioSpin [27]. The current version of the RS EPR algorithm solves an ill-posed problem – that the solution is unstable to small variations in the experimental parameters and noise – as two independent well-posed problems.…”

Section: Introductionmentioning

confidence: 99%

Full cycle rapid scan EPR deconvolution algorithm

Tseytlin

2017

Journal of Magnetic Resonance

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Rapid scan electron paramagnetic resonance (RS EPR) is a continuous-wave (CW) method that combines narrowband excitation and broadband detection. Sinusoidal magnetic field scans that span the entire EPR spectrum cause electron spin excitations twice during the scan period. Periodic transient RS signals are digitized and time-averaged. Deconvolution of absorption spectrum from the measured full-cycle signal is an ill-posed problem that does not have a stable solution because the magnetic field passes the same EPR line twice per sinusoidal scan during up- and down-field passages. As a result, RS signals consist of two contributions that need to be separated and postprocessed individually. Deconvolution of either of the contributions is a well-posed problem that has a stable solution. The current version of the RS EPR algorithm solves the separation problem by cutting the full-scan signal into two half-period pieces. This imposes a constraint on the experiment; the EPR signal must completely decay by the end of each half-scan in order to not be truncated. The constraint limits the maximum scan frequency and, therefore, the RS signal-to-noise gain. Faster scans permit the use of higher excitation powers without saturating the spin system, translating into a higher EPR sensitivity. A stable, full-scan algorithm is described in this paper that does not require truncation of the periodic response. This algorithm utilizes the additive property of linear systems: the response to a sum of two inputs is equal the sum of responses to each of the inputs separately. Based on this property, the mathematical model for CW RS EPR can be replaced by that of a sum of two independent full-cycle pulsed field-modulated experiments. In each of these experiments, the excitation power equals to zero during either up- or down-field scan. The full-cycle algorithm permits approaching the upper theoretical scan frequency limit; the transient spin system response must decay within the scan period. Separation of the interfering up- and down-field scan responses remains a challenge for reaching the full potential of this new method. For this reason, only a factor of two increase in the scan rate was achieved, in comparison with the standard half-scan RS EPR algorithm. It is important for practical use that faster scans not necessarily increase the signal bandwidth because acceleration of the Larmor frequency driven by the changing magnetic field changes its sign after passing the inflection points on the scan. The half-scan and full-scan algorithms are compared using a LiNC-BuO spin probe of known line-shape, demonstrating that the new method produces stable solutions when RS signals do not completely decay by the end of each half-scan.

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Rapid Scan Electron Paramagnetic Resonance Opens New Avenues for Imaging Physiologically Important Parameters <em>In Vivo</em>

Cited by 7 publications

References 33 publications

EPR Everywhere

EPR Everywhere

In vivo electron paramagnetic resonance oximetry and applications in the brain

Full cycle rapid scan EPR deconvolution algorithm

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