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Sato-Akaba H, Sakai T, Hirata H. Generation of transmission wave with low AM noise for sub-GHz CW-EPR spectrometer. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2024; 360:107633. [PMID: 38394999 DOI: 10.1016/j.jmr.2024.107633] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2023] [Revised: 01/13/2024] [Accepted: 02/05/2024] [Indexed: 02/25/2024]
Abstract
This study describes a technique to clean amplitude modulation (AM) noise of RF transmission waves, which is used to observe the sub-GHz CW-EPR spectrum. An RF transmitter amplifier that has the function of cleaning AM noise has been developed. Cleaning of the AM noise was owing to saturation of the output at the amplifier. Three stages of the amplifiers in series could effectively suppress the AM noise to about -176 dBc/Hz and -183 dBc/Hz at offset frequency of 10 kHz and 100 kHz, respectively at the carrier frequency of 750 MHz and the output power of 29 dBm. Since phase modulation (PM) noise is suppressed by phase sensitive detection, the AM noise in the transmission is dominant cause of the noise in the sub-GHz CW-EPR absorption spectrum using a reflection bridge, which depends on the quality factor of the resonator and the power of the RF transmission. The additive phase modulation (PM) noise of this amplifier was -171 dBc/Hz at an offset frequency of 100 kHz, which indicated that the frequency modulation (FM) of the transmission wave was not distorted with this amplifier. Therefore, conventional CW-EPR spectrometers that typically require FM for automatic frequency control or automatic tunning control can use this technique to increase sensitivity.
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Affiliation(s)
- Hideo Sato-Akaba
- Department of Systems Innovation, Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama-cho, Toyonaka, Osaka 560-8531, Japan.
| | - Tsukasa Sakai
- Department of Systems Innovation, Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama-cho, Toyonaka, Osaka 560-8531, Japan
| | - Hiroshi Hirata
- Division of Bioengineering and Bioinformatics, Faculty of Information Science and Technology, Hokkaido University, North 14, West 9, Kita-ku, Sapporo 060-0814, Japan
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Enomoto A, Ichikawa K. Research and Development of Preclinical Overhauser-Enhanced Magnetic Resonance Imaging. Antioxid Redox Signal 2022; 37:1094-1110. [PMID: 35369734 DOI: 10.1089/ars.2022.0038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Significance: Imaging free radicals, including reactive oxygen species and reactive nitrogen species, can be useful for understanding the pathology of diseases in animal disease models, as they are related to various physiological functions or diseases. Among the methods used for imaging free radicals, Overhauser-enhanced magnetic resonance imaging (OMRI) has a short image acquisition time and high spatial resolution. Therefore, OMRI is used to obtain various biological parameters. In this study, we review the methodology for improving the biological OMRI system and its applications. Recent Advances: The sensitivity of OMRI systems has been enhanced significantly to allow the visualization of various biological parameters, such as redox state, partial oxygen pressure, and pH, in different body parts of small animals, using spin probes. Furthermore, both endogenous free radicals and exogenous free radicals present in drugs can be visualized using OMRI. Critical Issues: To acquire accurate biological parameters at a high resolution, it is essential to increase the electron paramagnetic resonance (EPR) excitation efficiency and achieve a high enhancement factor. In addition, the size and magnetic field strength also need to be optimized for the measurement target. Future Directions: The advancement of in vivo OMRI techniques will be useful for understanding the pathology, diagnosis, and evaluation of therapeutic effects of drugs in various disease models. Antioxid. Redox Signal. 37, 1094-1110.
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Affiliation(s)
- Ayano Enomoto
- Department of Biophysical Chemistry, Faculty of Pharmaceutical Sciences, Nagasaki International University, Sasebo, Japan
| | - Kazuhiro Ichikawa
- Department of Biophysical Chemistry, Faculty of Pharmaceutical Sciences, Nagasaki International University, Sasebo, Japan
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Buchanan LA, Woodcock LB, Rinard GA, Quine RW, Shi Y, Eaton SS, Eaton GR. 250 MHz Rapid Scan Cross Loop Resonator. APPLIED MAGNETIC RESONANCE 2019; 50:333-345. [PMID: 30799909 PMCID: PMC6380496 DOI: 10.1007/s00723-018-1078-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
A 25 mm diameter 250 MHz crossed-loop resonator was designed for rapid scan electron paramagnetic resonance imaging. It has a saddle coil for the driven resonator and a fine wire, loop gap resonator for the sample resonator. There is good separation of E and B fields and high isolation between the two resonators, permitting a wide range of sample types to be measured. Applications to imaging of nitroxide, trityl, and LiPc samples illustrate the utility of the resonator. Using this resonator and a trityl sample the signal-to-noise of a rapid scan absorption spectrum is about 20 times higher than for a first-derivative CW spectrum.
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Affiliation(s)
- Laura A. Buchanan
- Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80210
| | - Lukas B. Woodcock
- Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80210
| | - George A. Rinard
- School of Engineering and Computer Science, University of Denver, Denver, CO 80210
| | - Richard W. Quine
- School of Engineering and Computer Science, University of Denver, Denver, CO 80210
| | - Yilin Shi
- Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80210
| | - Sandra S. Eaton
- Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80210
| | - Gareth R. Eaton
- Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80210
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Buchanan LA, Rinard GA, Quine RW, Eaton SS, Eaton GR. Tabletop 700 MHz electron paramagnetic resonance imaging spectrometer. CONCEPTS IN MAGNETIC RESONANCE. PART B, MAGNETIC RESONANCE ENGINEERING 2018; 48B:e21384. [PMID: 30804714 PMCID: PMC6386469 DOI: 10.1002/cmr.b.21384] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Accepted: 08/11/2018] [Indexed: 06/05/2023]
Abstract
Low frequency electron paramagnetic resonance imaging is a powerful tool to non-invasively measure the physiological status of tumors. Here, we report on the design and functionality of a rapid scan and pulse table-top imaging spectrometer based around an arbitrary waveform generator and 25mm cross-loop resonator operating at 700 MHz. Two and four-dimensional rapid scan spectral-spatial images are presented. This table-top imager is a prototype for future pre-clinical imagers.
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Affiliation(s)
- Laura A. Buchanan
- Department of Chemistry and Biochemistry and Center for EPR Imaging of In Vivo Physiology, University of
Denver, Denver, CO 80210
| | - George A. Rinard
- School of Engineering and Computer Science and Center for EPR Imaging of In Vivo Physiology, University of
Denver, Denver, CO 80210
| | - Richard W. Quine
- School of Engineering and Computer Science and Center for EPR Imaging of In Vivo Physiology, University of
Denver, Denver, CO 80210
| | - Sandra S. Eaton
- Department of Chemistry and Biochemistry and Center for EPR Imaging of In Vivo Physiology, University of
Denver, Denver, CO 80210
| | - Gareth R. Eaton
- Department of Chemistry and Biochemistry and Center for EPR Imaging of In Vivo Physiology, University of
Denver, Denver, CO 80210
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Rinard GA, Quine RW, Buchanan LA, Eaton SS, Eaton GR, Epel B, Sundramoorthy SV, Halpern HJ. Resonators for In Vivo Imaging: Practical Experience. APPLIED MAGNETIC RESONANCE 2017; 48:1227-1247. [PMID: 29391664 PMCID: PMC5788320 DOI: 10.1007/s00723-017-0947-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Resonators for preclinical electron paramagnetic resonance imaging have been designed primarily for rodents and rabbits and have internal diameters between 16 and 51 mm. Lumped circuit resonators include loop-gap, Alderman-Grant, and saddle coil topologies and surface coils. Bimodal resonators are useful for isolating the detected signal from incident power and reducing dead time in pulse experiments. Resonators for continuous wave, rapid scan, and pulse experiments are described. Experience at the University of Chicago and University of Denver in design of resonators for in vivo imaging is summarized.
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Affiliation(s)
- George A Rinard
- Center for EPR Imaging In Vivo Physiology, Department of Chemistry and Biochemistry and School of Engineering and Computer Science, University of Denver, Denver, CO 80210, USA
| | - Richard W Quine
- Center for EPR Imaging In Vivo Physiology, Department of Chemistry and Biochemistry and School of Engineering and Computer Science, University of Denver, Denver, CO 80210, USA
| | - Laura A Buchanan
- Center for EPR Imaging In Vivo Physiology, Department of Chemistry and Biochemistry and School of Engineering and Computer Science, University of Denver, Denver, CO 80210, USA
| | - Sandra S Eaton
- Center for EPR Imaging In Vivo Physiology, Department of Chemistry and Biochemistry and School of Engineering and Computer Science, University of Denver, Denver, CO 80210, USA
| | - Gareth R Eaton
- Center for EPR Imaging In Vivo Physiology, Department of Chemistry and Biochemistry and School of Engineering and Computer Science, University of Denver, Denver, CO 80210, USA
| | - Boris Epel
- Center for EPR Imaging In Vivo Physiology, Department of Radiation and Cellular Oncology, University of Chicago, IL, USA
| | - Subramanian V Sundramoorthy
- Center for EPR Imaging In Vivo Physiology, Department of Radiation and Cellular Oncology, University of Chicago, IL, USA
| | - Howard J Halpern
- Center for EPR Imaging In Vivo Physiology, Department of Radiation and Cellular Oncology, University of Chicago, IL, USA
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Amida T, Nakaoka R, Komarov DA, Yamamoto K, Inanami O, Matsumoto S, Hirata H. A 750-MHz Electronically Tunable Resonator Using Microstrip Line Couplers for Electron Paramagnetic Resonance Imaging of a Mouse Tumor-Bearing Leg. IEEE Trans Biomed Eng 2017; 65:1124-1132. [PMID: 28841547 DOI: 10.1109/tbme.2017.2743232] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
OBJECTIVE The purpose of this work was to develop an electronically tunable resonator operating at 750 MHz for continuous-wave electron paramagnetic resonance (CW-EPR) imaging of a mouse tumor-bearing leg. METHODS The resonator had a multi-coil parallel-gap structure with a sample space of 16 mm in diameter and 20 mm in length. Microstrip line couplers were used in conjunction with varactor diodes to enable resonance frequency adjustment and to reduce the nonlinear effects of the varactor diodes. The resonator was modeled by the finite-element method and a microwave circuit simulation was performed to clarify its radiofrequency characteristics. RESULTS A tunable resonator was evaluated in terms of its resonance frequency, tunable frequency band, and conversion efficiency of the RF magnetic field. The developed resonator provided a tunable frequency band of 4 MHz at a central frequency of 747 MHz and a conversion efficiency of 34 μT/W1/2. To demonstrate the application of this tunable resonator to EPR imaging, three-dimensional EPR images of a sample solution and a mouse tumor-bearing leg were obtained. CONCLUSION The developed tunable resonator satisfied our initial requirements for in vivo EPR imaging and may be able to be further improved using the present finite-element and circuit models if any problems arise during future practical applications. SIGNIFICANCE This work may help to promote EPR imaging of tumor-bearing mice in cancer-related studies.
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Abstract
Electron paramagnetic resonance (EPR) spectroscopy and imaging (EPRI) are deeply rooted in the basic and quantum physics, but the spectrum of their applications in modern experimental and clinical dermatology and cosmetology is surprisingly wide. The main aim of this review was to show the physical foundation, technical limitations and versatility of this method in skin studies. Free radical and metal ion detection, EPR dosimetry, melanin study, spin trapping, spin labelling, oximetry and NO-metry, EPR imaging, new generation methods of EPR and EPR/NMR hybrid technology used under ex vivo and in vivo regime are portrayed in the context of clinical and experimental skin research to study problems such as oxidative and nitrosative stress generated by UV or inflammation, skin oxygenation, hydration of corneal layer of epidermis, transport and metabolism of drugs and cosmeceutics, skin carcinogenesis, skin tumors and many others. A part of the paper is devoted to hair and nail research. The review of dermatological applications of EPR is supplemented with a handful of advice concerning practical aspects of EPR experimentation and usage of EPR reagents.
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Affiliation(s)
- Przemyslaw M Plonka
- Department of Biophysics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Kraków, Poland.
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