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Woodcock LB, Legenzov EA, Dirda NDA, Kao JPY, Eaton GR, Eaton SS. Cyclic Disulfide-Bridged Dinitroxide Biradical for Measuring Thiol Redox Status by Electron Paramagnetic Resonance. J Phys Chem B 2023; 127:8762-8768. [PMID: 37811968 PMCID: PMC10990597 DOI: 10.1021/acs.jpcb.3c03387] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/10/2023]
Abstract
Among low-molecular-weight thiols, glutathione (GSH) is the main antioxidant in the cell, and its concentration is an indicator of the redox status. A cyclic disulfide-linked dinitroxide was designed for monitoring GSH by electron-paramagnetic resonance (EPR) spectroscopy. Reaction of the disulfide with GSH and three other thiols was measured at 9.6 GHz (X-band) and shown to be of first order in thiols. It is proposed that the reaction of the disulfide with 1 equiv of thiolate produced a short-lived intermediate that reacts with 1 equiv of thiolate to produce the cleavage product. The equilibrium ratio of the cleaved and intact disulfide is a measure of the redox state. Since the long-term goal is to use the disulfide to probe physiology in vivo, the feasibility of EPR spectroscopy and imaging of the disulfide and its cleavage product was demonstrated at 1 GHz (L-band).
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Affiliation(s)
- Lukas B. Woodcock
- Department of Chemistry and Biochemistry, University of Denver, Denver, Colorado 80208, United States
| | - Eric A. Legenzov
- Center for Biomedical Engineering & Technology, and Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland 21201, United States
| | - Nathaniel D. A. Dirda
- Center for Biomedical Engineering & Technology, and Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland 21201, United States
| | - Joseph P. Y. Kao
- Center for Biomedical Engineering & Technology, and Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland 21201, United States
| | - Gareth R. Eaton
- Department of Chemistry and Biochemistry, University of Denver, Denver, Colorado 80208, United States
| | - Sandra S. Eaton
- Department of Chemistry and Biochemistry, University of Denver, Denver, Colorado 80208, United States
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2
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Komarov DA, Samouilov A, Hirata H, Zweier JL. High fidelity triangular sweep of the magnetic field for millisecond scan EPR imaging. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2021; 329:107024. [PMID: 34198184 PMCID: PMC8316393 DOI: 10.1016/j.jmr.2021.107024] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Revised: 05/28/2021] [Accepted: 06/07/2021] [Indexed: 06/13/2023]
Abstract
Linearity of the magnetic field sweep is important for high resolution continuous wave EPR imaging. Driving the field with triangular wave function is the most efficient way to scan EPR projections. However, the magnetic field sweep profile can be significantly distorted during fast millisecond projection scan. In this work, we introduce a method to generate highly linear and properly symmetrical triangular sweeps of the magnetic field using calibrated harmonics of the triangular wave function. First, the frequency response function of the EPR magnet and its power circuitry was obtained. For this, the field sweeping coil was driven with sinusoidal signals of different frequencies and the actual magnetic field inside the magnet was recorded. To cover wide range of frequencies, the measurements were carried out independently using gaussmeter, Hall-effect linear sensor integrated circuit, and an inductance coil. For each frequency, the system gain and the phase delay were determined. These data were used to adjust the amplitudes and the phases of individual harmonics of the triangular wave function. After the calibration, the maximum deviation of the magnetic field from the linear function was 0.05% of sweep width for 4 ms scan. The maximum discrepancy between the forward and the reverse scan was less than 0.04%. Sweep overhead time for changing the scan direction was 5%. The proposed approach allows generation of high fidelity triangular magnetic field sweeps with accuracy better than 0.1% for the range of the magnetic field sweep widths up to 48 G and scan duration from 10 s down to 1 ms.
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Affiliation(s)
- Denis A Komarov
- The EPR Center and Department of Internal Medicine, Division of Cardiovascular Medicine, Davis Heart and Lung Institute, The Ohio State University College of Medicine, Columbus, OH 43210, USA
| | - Alexandre Samouilov
- The EPR Center and Department of Internal Medicine, Division of Cardiovascular Medicine, Davis Heart and Lung Institute, The Ohio State University College of Medicine, Columbus, OH 43210, USA
| | - 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
| | - Jay L Zweier
- The EPR Center and Department of Internal Medicine, Division of Cardiovascular Medicine, Davis Heart and Lung Institute, The Ohio State University College of Medicine, Columbus, OH 43210, USA.
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Kozioł J, Rajda P, Rumian R, Oleś T, Budzioch P, Gurbiel RJ, Froncisz W. Continuous wave electron paramagnetic resonance L-band spectrometer with direct digitalization using time-locked subsampling. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2021; 322:106870. [PMID: 33248331 DOI: 10.1016/j.jmr.2020.106870] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Revised: 11/02/2020] [Accepted: 11/03/2020] [Indexed: 06/12/2023]
Abstract
This article describes a novel digital L-band EPR spectrometer. The spectrometer uses direct digital detection with time-locked subsampling (TLSS). The device consists of a microwave bridge equipped with a microwave source based on direct digital synthesis (DDS) and a digital receiver. DDS technology combined with an ultra-low noise 1 GHz master clock allowed the development of a digitally controlled microwave source with exceptionally good phase noise characteristics. The obtained level of phase noise is as low as -140 dBc/Hz at 30.5 kHz from the carrier frequency of 1.15 GHz, which is important when registering the EPR dispersion signal. The receiver is equipped with a high-speed A/D converter that enables direct digitalization of the L-band microwave signal. The obtained discrete data are then buffered and averaged in a programmable logic FPGA device. Data packets from FPGA are transferred to a DSP microcontroller that correlates them with the appropriate reference signals. This detection algorithm requires time locking of the generator and the receiver, which is ensured by clocking both devices from the same reference source. This procedure allows the simultaneous detection of the absorption and dispersion signals at the magnetic field modulation frequency and at any of its harmonics. The software to control the spectrometer was designed in the LabView programming environment. The program also allows further data processing. To the best of our knowledge, the described spectrometer is one of the first full implementation of the direct digital detection technique which could replace conventional analog CW spectrometers that utilize magnetic field modulation. For an 11 µm aqueous TEMPOL solution, the new spectrometer obtained a S/N ratio greater than 160 for an EPR spectrum registered in 69 s.
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Affiliation(s)
- J Kozioł
- Jagiellonian University, Faculty of Biochemistry, Biophysics and Biotechnology, Department of Molecular Biophysics, 7 Gronostajowa St., 30-387 Krakow, Poland
| | - P Rajda
- AGH University of Science and Technology, Faculty of Computer Science, Electronics and Telecommunications, Department of Electronics, al. Mickiewicza 30, 30-059 Krakow, Poland
| | - R Rumian
- AGH University of Science and Technology, Faculty of Computer Science, Electronics and Telecommunications, Department of Electronics, al. Mickiewicza 30, 30-059 Krakow, Poland
| | - T Oleś
- Jagiellonian University, Faculty of Biochemistry, Biophysics and Biotechnology, Department of Molecular Biophysics, 7 Gronostajowa St., 30-387 Krakow, Poland
| | - P Budzioch
- Jagiellonian University, Faculty of Biochemistry, Biophysics and Biotechnology, Department of Molecular Biophysics, 7 Gronostajowa St., 30-387 Krakow, Poland
| | - R J Gurbiel
- Jagiellonian University, Faculty of Biochemistry, Biophysics and Biotechnology, Department of Molecular Biophysics, 7 Gronostajowa St., 30-387 Krakow, Poland
| | - W Froncisz
- Jagiellonian University, Faculty of Biochemistry, Biophysics and Biotechnology, Department of Molecular Biophysics, 7 Gronostajowa St., 30-387 Krakow, Poland.
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Gonet M, Baranowski M, Czechowski T, Kucinska M, Plewinski A, Szczepanik P, Jurga S, Murias M. Multiharmonic electron paramagnetic resonance imaging as an innovative approach for in vivo studies. Free Radic Biol Med 2020; 152:271-279. [PMID: 32222471 DOI: 10.1016/j.freeradbiomed.2020.03.018] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/19/2020] [Revised: 03/03/2020] [Accepted: 03/23/2020] [Indexed: 12/17/2022]
Abstract
This work is the first report when multiharmonic analysis (MHA) was applied for electron paramagnetic resonance imaging (EPRI) for in vivo applications. Phantom studies were performed for established methodology, and in vivo imaging was conduct as a proof-of-concept. Phantom studies showed at least six times improvement of the signal - to - noise (S/N) ratio. Application MHA for 3D EPR in vivo imaging provides images of spin probe distribution in mouse head. The EPRI, in combination with nitroxide and trityl spin probe, was performed to obtained 3D EPR in vivo images using MHA. For both used spin probes, MHA provided images with better S/N ratio, especially in the case of nitroxide, where projections obtained using conventional CW did not allow for reconstructing reliable data. Trityl radical exhibited high resolution and quality of obtained images after MHA. The MHA methodology allows the selection of a second modulation amplitude even 40 times higher than the natural EPR linewidth of the spin probe without line shape distortion, which highly improves the sensitivity of the acquired signal and allowing for imaging mice regardless of their size in a routine animal experiment.
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Affiliation(s)
- Michal Gonet
- Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland
| | - Mikolaj Baranowski
- Novilet, Poznan, Poland; Faculty of Physics, Adam Mickiewicz University, Poznan, Poland
| | | | - Malgorzata Kucinska
- Department of Toxicology, Poznan University of Medical Science, Poznan, Poland
| | | | | | - Stefan Jurga
- NanoBioMedical Centre, Adam Mickiewicz University, Poznan, Poland
| | - Marek Murias
- Department of Toxicology, Poznan University of Medical Science, Poznan, Poland.
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Shi Y, Eaton SS, Eaton GR. Rapid-scan EPR imaging of a phantom comprised of species with different linewidths and relaxation times. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2019; 308:106593. [PMID: 31520789 PMCID: PMC6829054 DOI: 10.1016/j.jmr.2019.106593] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Revised: 09/05/2019] [Accepted: 09/06/2019] [Indexed: 06/10/2023]
Abstract
As a demonstration of the application of rapid-scan EPR to imaging at low frequency and magnetic field, a multi-compartment phantom containing six different samples was imaged. The samples were nitroxide radicals, trityl (substituted triarylmethyl) radicals, and the oxygen-sensitive solid lithium phthalocyanine (LiPc), all of which are useful for in vivo imaging. The 2D spectral-spatial image demonstration was performed at 250 MHz, with samples in sealed tubes of various sizes arranged in a 3D-printed plastic holder. Maximum gradients of 10 G/cm gave a spatial resolution of about 0.1 mm for the narrow trityl and LiPc signals and about 1 mm for the nitroxide. The importance of proper selection of resonator bandwidth and scan rate for obtaining accurate linewidth information is demonstrated for a case in which the phantom is composed of species with signal linewidths and relaxation times that differ by more than a factor of 10.
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Affiliation(s)
- Yilin Shi
- Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80210, USA
| | - Sandra S Eaton
- Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80210, USA
| | - Gareth R Eaton
- Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80210, USA.
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6
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Tseytlin O, Guggilapu P, Bobko AA, AlAhmad H, Xu X, Epel B, O'Connell R, Hoblitzell EH, Eubank TD, Khramtsov VV, Driesschaert B, Kazkaz E, Tseytlin M. Modular imaging system: Rapid scan EPR at 800 MHz. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2019; 305:94-103. [PMID: 31238278 PMCID: PMC6656609 DOI: 10.1016/j.jmr.2019.06.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Revised: 06/04/2019] [Accepted: 06/05/2019] [Indexed: 06/05/2023]
Abstract
An electron paramagnetic resonance (EPR) imaging system has been custom built for use in pre-clinical and, potentially, clinical studies. Commercial standalone modules have been used in the design that are MATLAB-controlled. The imaging system combines digital and analog technologies. It was designed to achieve maximum flexibility and versatility and to perform standard and novel user-defined experiments. This design goal is achieved by frequency mixing of an arbitrary waveform generator (AWG) output at the intermediate frequency (IF) with a constant source frequency (SF). Low noise SF at 250, 750, and 1000 MHz are available in the system. A wide range of frequencies from near-baseband to L-band can be generated as a result. Two-stage downconversion at the signal detection side is implemented that enables multi-frequency EPR capability. In the first stage, the signal frequency is converted to IF. A novel AWG-enabled digital auto-frequency control method that operates at IF is described that is used for automatic resonator tuning. Quadrature baseband EPR signal is generated in the second downconversion step. The semi-digital approach of mixing low-noise frequency sources with an AWG permits generation of arbitrary excitation patterns that include but are not limited to frequency sweeps for resonator tuning and matching, continuous-wave, and pulse sequences. Presented in this paper is the demonstration of rapid scan (RS) EPR imaging implemented at 800 MHz. Generation of stable magnetic scan waveforms is critical for the RS method. A digital automatic scan control (DASC) system was developed for sinusoidal magnetic field scans. DASC permits tight control of both amplitude and phase of the scans. A surface loop resonator was developed using 3D printing technology. RS EPR imaging system was validated using sample phantoms. In vivo imaging of a breast cancer mouse model is demonstrated.
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Affiliation(s)
- Oxana Tseytlin
- Biochemistry Department, West Virginia University, Morgantown, WV 26506, USA; In Vivo Multifunctional Magnetic Resonance Center at Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, WV 26506, USA
| | - Priyaankadevi Guggilapu
- Biochemistry Department, West Virginia University, Morgantown, WV 26506, USA; Lane Department of Computer Science and Electrical Engineering, West Virginia University, Morgantown, WV 26506, USA; In Vivo Multifunctional Magnetic Resonance Center at Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, WV 26506, USA
| | - Andrey A Bobko
- Biochemistry Department, West Virginia University, Morgantown, WV 26506, USA; In Vivo Multifunctional Magnetic Resonance Center at Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, WV 26506, USA
| | - Hussien AlAhmad
- Biochemistry Department, West Virginia University, Morgantown, WV 26506, USA; In Vivo Multifunctional Magnetic Resonance Center at Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, WV 26506, USA; Department of Industrial & Management Systems Engineering, West Virginia University, Morgantown, WV 26506, USA
| | - Xuan Xu
- Biochemistry Department, West Virginia University, Morgantown, WV 26506, USA; Lane Department of Computer Science and Electrical Engineering, West Virginia University, Morgantown, WV 26506, USA; In Vivo Multifunctional Magnetic Resonance Center at Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, WV 26506, USA
| | - Boris Epel
- Center for EPR Imaging In Vivo Physiology, University of Chicago, IL 60637, USA
| | - Ryan O'Connell
- Biochemistry Department, West Virginia University, Morgantown, WV 26506, USA; In Vivo Multifunctional Magnetic Resonance Center at Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, WV 26506, USA
| | - Emily H Hoblitzell
- In Vivo Multifunctional Magnetic Resonance Center at Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, WV 26506, USA; Department of Microbiology, Immunology & Cell Biology, West Virginia University School of Medicine, Morgantown, WV 26506, USA
| | - Timothy D Eubank
- In Vivo Multifunctional Magnetic Resonance Center at Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, WV 26506, USA; Department of Microbiology, Immunology & Cell Biology, West Virginia University School of Medicine, Morgantown, WV 26506, USA
| | - Valery V Khramtsov
- Biochemistry Department, West Virginia University, Morgantown, WV 26506, USA; In Vivo Multifunctional Magnetic Resonance Center at Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, WV 26506, USA
| | - Benoit Driesschaert
- In Vivo Multifunctional Magnetic Resonance Center at Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, WV 26506, USA; Department of Pharmaceutical Sciences, West Virginia University, Morgantown, WV 26506, USA
| | - Eiad Kazkaz
- Biochemistry Department, West Virginia University, Morgantown, WV 26506, USA; Lane Department of Computer Science and Electrical Engineering, West Virginia University, Morgantown, WV 26506, USA; In Vivo Multifunctional Magnetic Resonance Center at Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, WV 26506, USA
| | - Mark Tseytlin
- Biochemistry Department, West Virginia University, Morgantown, WV 26506, USA; In Vivo Multifunctional Magnetic Resonance Center at Robert C. Byrd Health Sciences Center, West Virginia University, Morgantown, WV 26506, USA.
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7
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Sato-Akaba H, Tseytlin M. Development of an L-band rapid scan EPR digital console. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2019; 304:42-52. [PMID: 31100585 PMCID: PMC7549020 DOI: 10.1016/j.jmr.2019.05.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Revised: 05/09/2019] [Accepted: 05/10/2019] [Indexed: 06/05/2023]
Abstract
The development of a digital console for in-vivo rapid scan electron paramagnetic resonance (RS-EPR) spectroscopy and imaging is described in detail. The console was build using field programmable gate array (FGPA) technology that permits real-time control of the resonator and scanning magnetic fields during the measurements. Automatic resonator tuning and matching are achieved by implementing a digital feedback control system and using voltage-tunable capacitors. A band-pass subsampling method is used to directly digitize EPR signals at the carrier frequencies of about 1.2 GHz. The magnetic field scan waveforms, excitation EPR frequency, and sampling clock are all internally synchronized. Full-cycle RS-EPR signals are accumulated in the FPGA in real time without any time gaps. The result is the elimination of the re-arm time, during which data are not acquired. The proposed design in this manuscript has a small footprint and is relatively low cost. The FPGA-based RS-EPR system was tested using standard LiNc-BuO and tempone-d16 samples. The RS-EPR linewidth of the LiNc-BuO sample was consistent with an independent pulsed EPR measurement.
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Affiliation(s)
- Hideo Sato-Akaba
- Department of Systems Innovation, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan.
| | - Mark Tseytlin
- Department of Biochemistry, School of Medicine, West Virginia University, Morgantown, WV, USA
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Samouilov A, Ahmad R, Boslett J, Liu X, Petryakov S, Zweier JL. Development of a fast-scan EPR imaging system for highly accelerated free radical imaging. Magn Reson Med 2019; 82:842-853. [PMID: 31020713 DOI: 10.1002/mrm.27759] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Revised: 03/07/2019] [Accepted: 03/11/2019] [Indexed: 01/01/2023]
Abstract
PURPOSE In continuous wave EPR imaging, the acquisition of high-quality images was previously limited by the requisite long acquisition times of each image projection that was typically greater than 1 second. To accelerate the process of image acquisition facilitating greater numbers of projections and higher image resolution, instrumentation was developed to greatly accelerate the magnetic field scan that is used to obtain each EPR image projection. METHODS A low-inductance solenoidal coil for field scanning was used along with a spherical solenoid air core magnet, and scans were driven by triangular symmetric waves, allowing forward and reverse spectrum acquisition as rapid as 3.8 ms. The uniform distribution of projections was used to optimize the contribution of projections for 3D image reconstruction. RESULTS Using this fast-scan EPR system, high-quality EPR images of phantoms and perfused rat hearts were performed using trityl or nanoparticulate LiNcBuO (lithium octa-n-butoxy-substituted naphthalocyanine) probes with fast-scan EPR imaging at L-band, achieving spatial resolutions of up to 250 micrometers in 1 minute. CONCLUSION Fast-scan EPR imaging can greatly facilitate the efficient and precise mapping of the spatial distribution of free radical and other paramagnetic probes in living systems.
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Affiliation(s)
- Alexandre Samouilov
- Davis Heart and Lung Research Institute and the Division of Cardiovascular Medicine, Department of Internal Medicine, The Ohio State University College of Medicine, Columbus, Ohio
| | - Rizwan Ahmad
- Davis Heart and Lung Research Institute and the Division of Cardiovascular Medicine, Department of Internal Medicine, The Ohio State University College of Medicine, Columbus, Ohio
| | - James Boslett
- Davis Heart and Lung Research Institute and the Division of Cardiovascular Medicine, Department of Internal Medicine, The Ohio State University College of Medicine, Columbus, Ohio
| | - Xiaoping Liu
- Davis Heart and Lung Research Institute and the Division of Cardiovascular Medicine, Department of Internal Medicine, The Ohio State University College of Medicine, Columbus, Ohio
| | - Sergey Petryakov
- Geisel School of Medicine, Dartmouth College, Hanover, New Hampshire
| | - Jay L Zweier
- Davis Heart and Lung Research Institute and the Division of Cardiovascular Medicine, Department of Internal Medicine, The Ohio State University College of Medicine, Columbus, Ohio
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Komarov DA, Hirata H. Fast backprojection-based reconstruction of spectral-spatial EPR images from projections with the constant sweep of a magnetic field. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2017; 281:44-50. [PMID: 28549338 DOI: 10.1016/j.jmr.2017.05.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Revised: 05/11/2017] [Accepted: 05/12/2017] [Indexed: 06/07/2023]
Abstract
In this paper, we introduce a procedure for the reconstruction of spectral-spatial EPR images using projections acquired with the constant sweep of a magnetic field. The application of a constant field-sweep and a predetermined data sampling rate simplifies the requirements for EPR imaging instrumentation and facilitates the backprojection-based reconstruction of spectral-spatial images. The proposed approach was applied to the reconstruction of a four-dimensional numerical phantom and to actual spectral-spatial EPR measurements. Image reconstruction using projections with a constant field-sweep was three times faster than the conventional approach with the application of a pseudo-angle and a scan range that depends on the applied field gradient. Spectral-spatial EPR imaging with a constant field-sweep for data acquisition only slightly reduces the signal-to-noise ratio or functional resolution of the resultant images and can be applied together with any common backprojection-based reconstruction algorithm.
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Affiliation(s)
- Denis A Komarov
- Division of Bioengineering and Bioinformatics, Graduate School of Information Science and Technology, Hokkaido University, North 14, West 9, Kita-ku, Sapporo 060-0814, Japan
| | - Hiroshi Hirata
- Division of Bioengineering and Bioinformatics, Graduate School of Information Science and Technology, Hokkaido University, North 14, West 9, Kita-ku, Sapporo 060-0814, Japan.
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Epel B, Kotecha M, Halpern HJ. In vivo preclinical cancer and tissue engineering applications of absolute oxygen imaging using pulse EPR. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2017; 280:149-157. [PMID: 28552587 DOI: 10.1016/j.jmr.2017.04.017] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Revised: 04/27/2017] [Accepted: 04/28/2017] [Indexed: 06/07/2023]
Abstract
The value of any measurement and a fortiori any measurement technology is defined by the reproducibility and the accuracy of the measurements. This implies a relative freedom of the measurement from factors confounding its accuracy. In the past, one of the reasons for the loss of focus on the importance of imaging oxygen in vivo was the difficulty in obtaining reproducible oxygen or pO2 images free from confounding variation. This review will briefly consider principles of electron paramagnetic oxygen imaging and describe how it achieves absolute oxygen measurements. We will provide a summary review of the progress in biomedical EPR imaging, predominantly in cancer biology research, discuss EPR oxygen imaging for cancer treatment and tissue graft assessment for regenerative medicine applications.
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Affiliation(s)
- Boris Epel
- Department of Radiation and Cellular Oncology, University of Chicago, Chicago, IL 60637, United States; Center for EPR Imaging In Vivo Physiology, University of Chicago, Chicago, IL 60637, United States
| | - Mrignayani Kotecha
- Richard and Loan Hill Department of Bioengineering, University of Illinois at Chicago, Chicago IL 60607, United States
| | - Howard J Halpern
- Department of Radiation and Cellular Oncology, University of Chicago, Chicago, IL 60637, United States; Center for EPR Imaging In Vivo Physiology, University of Chicago, Chicago, IL 60637, United States.
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11
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Eaton SS, Shi Y, Woodcock L, Buchanan LA, McPeak J, Quine RW, Rinard GA, Epel B, Halpern HJ, Eaton GR. Rapid-scan EPR imaging. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2017; 280:140-148. [PMID: 28579099 PMCID: PMC5523658 DOI: 10.1016/j.jmr.2017.02.013] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2016] [Revised: 02/17/2017] [Accepted: 02/18/2017] [Indexed: 05/12/2023]
Abstract
In rapid-scan EPR the magnetic field or frequency is repeatedly scanned through the spectrum at rates that are much faster than in conventional continuous wave EPR. The signal is directly-detected with a mixer at the source frequency. Rapid-scan EPR is particularly advantageous when the scan rate through resonance is fast relative to electron spin relaxation rates. In such scans, there may be oscillations on the trailing edge of the spectrum. These oscillations can be removed by mathematical deconvolution to recover the slow-scan absorption spectrum. In cases of inhomogeneous broadening, the oscillations may interfere destructively to the extent that they are not visible. The deconvolution can be used even when it is not required, so spectra can be obtained in which some portions of the spectrum are in the rapid-scan regime and some are not. The technology developed for rapid-scan EPR can be applied generally so long as spectra are obtained in the linear response region. The detection of the full spectrum in each scan, the ability to use higher microwave power without saturation, and the noise filtering inherent in coherent averaging results in substantial improvement in signal-to-noise relative to conventional continuous wave spectroscopy, which is particularly advantageous for low-frequency EPR imaging. This overview describes the principles of rapid-scan EPR and the hardware used to generate the spectra. Examples are provided of its application to imaging of nitroxide radicals, diradicals, and spin-trapped radicals at a Larmor frequency of ca. 250MHz.
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Affiliation(s)
- Sandra S Eaton
- Department of Chemistry and Biochemistry and Center for EPR Imaging In Vivo Physiology, University of Denver, Denver, CO 80210, United States
| | - Yilin Shi
- Department of Chemistry and Biochemistry and Center for EPR Imaging In Vivo Physiology, University of Denver, Denver, CO 80210, United States
| | - Lukas Woodcock
- Department of Chemistry and Biochemistry and Center for EPR Imaging In Vivo Physiology, University of Denver, Denver, CO 80210, United States
| | - Laura A Buchanan
- Department of Chemistry and Biochemistry and Center for EPR Imaging In Vivo Physiology, University of Denver, Denver, CO 80210, United States
| | - Joseph McPeak
- Department of Chemistry and Biochemistry and Center for EPR Imaging In Vivo Physiology, University of Denver, Denver, CO 80210, United States
| | - Richard W Quine
- School of Engineering and Computer Science and Center for EPR Imaging In Vivo Physiology, University of Denver, Denver, CO 80210, United States
| | - George A Rinard
- School of Engineering and Computer Science and Center for EPR Imaging In Vivo Physiology, University of Denver, Denver, CO 80210, United States
| | - Boris Epel
- Department of Radiation and Cellular Oncology and Center for EPR Imaging In Vivo Physiology, University of Chicago, Chicago, IL 60637, United States
| | - Howard J Halpern
- Department of Radiation and Cellular Oncology and Center for EPR Imaging In Vivo Physiology, University of Chicago, Chicago, IL 60637, United States
| | - Gareth R Eaton
- Department of Chemistry and Biochemistry and Center for EPR Imaging In Vivo Physiology, University of Denver, Denver, CO 80210, United States.
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12
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Colliez F, Gallez B, Jordan BF. Assessing Tumor Oxygenation for Predicting Outcome in Radiation Oncology: A Review of Studies Correlating Tumor Hypoxic Status and Outcome in the Preclinical and Clinical Settings. Front Oncol 2017; 7:10. [PMID: 28180110 PMCID: PMC5263142 DOI: 10.3389/fonc.2017.00010] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Accepted: 01/10/2017] [Indexed: 12/30/2022] Open
Abstract
Tumor hypoxia is recognized as a limiting factor for the efficacy of radiotherapy, because it enhances tumor radioresistance. It is strongly suggested that assessing tumor oxygenation could help to predict the outcome of cancer patients undergoing radiation therapy. Strategies have also been developed to alleviate tumor hypoxia in order to radiosensitize tumors. In addition, oxygen mapping is critically needed for intensity modulated radiation therapy (IMRT), in which the most hypoxic regions require higher radiation doses and the most oxygenated regions require lower radiation doses. However, the assessment of tumor oxygenation is not yet included in day-to-day clinical practice. This is due to the lack of a method for the quantitative and non-invasive mapping of tumor oxygenation. To fully integrate tumor hypoxia parameters into effective improvements of the individually tailored radiation therapy protocols in cancer patients, methods allowing non-invasively repeated, safe, and robust mapping of changes in tissue oxygenation are required. In this review, non-invasive methods dedicated to assessing tumor oxygenation with the ultimate goal of predicting outcome in radiation oncology are presented, including positron emission tomography used with nitroimidazole tracers, magnetic resonance methods using endogenous contrasts (R1 and R2*-based methods), and electron paramagnetic resonance oximetry; the goal is to highlight results of studies establishing correlations between tumor hypoxic status and patients’ outcome in the preclinical and clinical settings.
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Affiliation(s)
- Florence Colliez
- Biomedical Magnetic Resonance Group, Louvain Drug Research Institute, Université Catholique de Louvain , Brussels , Belgium
| | - Bernard Gallez
- Biomedical Magnetic Resonance Group, Louvain Drug Research Institute, Université Catholique de Louvain , Brussels , Belgium
| | - Bénédicte F Jordan
- Biomedical Magnetic Resonance Group, Louvain Drug Research Institute, Université Catholique de Louvain , Brussels , Belgium
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13
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Christodoulou AG, Redler G, Clifford B, Liang ZP, Halpern HJ, Epel B. Fast dynamic electron paramagnetic resonance (EPR) oxygen imaging using low-rank tensors. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2016; 270:176-182. [PMID: 27498337 PMCID: PMC5127203 DOI: 10.1016/j.jmr.2016.07.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Revised: 06/14/2016] [Accepted: 07/13/2016] [Indexed: 05/22/2023]
Abstract
Hypoxic tumors are resistant to radiotherapy, motivating the development of tools to image local oxygen concentrations. It is generally believed that stable or chronic hypoxia is the source of resistance, but more recent work suggests a role for transient hypoxia. Conventional EPR imaging (EPRI) is capable of imaging tissue pO2in vivo, with high pO2 resolution and 1mm spatial resolution but low imaging speed (10min temporal resolution for T1-based pO2 mapping), which makes it difficult to investigate the oxygen changes, e.g., transient hypoxia. Here we describe a new imaging method which accelerates dynamic EPR oxygen imaging, allowing 3D imaging at 2 frames per minute, fast enough to image transient hypoxia at the "speed limit" of observed pO2 change. The method centers on a low-rank tensor model that decouples the tradeoff between imaging speed, spatial coverage/resolution, and number of inversion times (pO2 accuracy). We present a specialized sparse sampling strategy and image reconstruction algorithm for use with this model. The quality and utility of the method is demonstrated in simulations and in vivo experiments in tumor bearing mice.
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Affiliation(s)
- Anthony G Christodoulou
- Center for EPR Imaging In Vivo Physiology, University of Chicago, Chicago, IL 60637, USA; Department of Electrical and Computer Engineering and Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Gage Redler
- Center for EPR Imaging In Vivo Physiology, University of Chicago, Chicago, IL 60637, USA; Department of Radiation and Cellular Oncology, University of Chicago, Chicago, IL 60637, USA
| | - Bryan Clifford
- Center for EPR Imaging In Vivo Physiology, University of Chicago, Chicago, IL 60637, USA; Department of Electrical and Computer Engineering and Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Zhi-Pei Liang
- Center for EPR Imaging In Vivo Physiology, University of Chicago, Chicago, IL 60637, USA; Department of Electrical and Computer Engineering and Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Howard J Halpern
- Center for EPR Imaging In Vivo Physiology, University of Chicago, Chicago, IL 60637, USA; Department of Radiation and Cellular Oncology, University of Chicago, Chicago, IL 60637, USA
| | - Boris Epel
- Center for EPR Imaging In Vivo Physiology, University of Chicago, Chicago, IL 60637, USA; Department of Radiation and Cellular Oncology, University of Chicago, Chicago, IL 60637, USA.
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14
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Jones CE, Berliner LJ. Nitroxide Spin-Labelling and Its Role in Elucidating Cuproprotein Structure and Function. Cell Biochem Biophys 2016; 75:195-202. [PMID: 27342129 DOI: 10.1007/s12013-016-0751-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Accepted: 06/11/2016] [Indexed: 10/21/2022]
Abstract
Copper is one of the most abundant biological metals, and its chemical properties mean that organisms need sophisticated and multilayer mechanisms in place to maintain homoeostasis and avoid deleterious effects. Studying copper proteins requires multiple techniques, but electron paramagnetic resonance (EPR) plays a key role in understanding Cu(II) sites in proteins. When spin-labels such as aminoxyl radicals (commonly referred to as nitroxides) are introduced, then EPR becomes a powerful technique to monitor not only the coordination environment, but also to obtain structural information that is often not readily available from other techniques. This information can contribute to explaining how cuproproteins fold and misfold. The theory and practice of EPR can be daunting to the non-expert; therefore, in this mini review, we explore how nitroxide spin-labelling can be used to help the inorganic biochemist gain greater understanding of cuproprotein structure and function in vitro and how EPR imaging may help improve understanding of copper homoeostasis in vivo.
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Affiliation(s)
- Christopher E Jones
- The School of Science and Health, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2759, Australia.
| | - Lawrence J Berliner
- Department of Chemistry and Biochemistry, University of Denver, Denver, CO, 80208-0183, USA
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15
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Tadyszak K, Boś-Liedke A, Jurga J, Baranowski M, Mrówczyński R, Chlewicki W, Jurga S, Czechowski T. Overmodulation of projections as signal-to-noise enhancement method in EPR imaging. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2016; 54:136-142. [PMID: 26364566 DOI: 10.1002/mrc.4330] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Revised: 07/08/2015] [Accepted: 08/04/2015] [Indexed: 06/05/2023]
Abstract
A study concerning the image quality in electron paramagnetic resonance imaging in two-dimensional spatial experiments is presented. The aim of the measurements was to improve the signal-to-noise ratio (SNR) of the projections and the reconstructed image by applying modulation amplitude higher than the radical electron paramagnetic resonance linewidth. Data were gathered by applying four constant modulation amplitudes, where one was below 1/3 (Amod = 0.04 mT) of the radical linewidth (ΔBpp = 0.14 mT). Three other modulation amplitude values were used in this experiment, leading to undermodulated (Amod < 1/3 ΔBpp), partially overmodulated (Amod ~ 1/3 ΔBpp) and fully overmodulated (Amod > > 1/3 ΔBpp) projections. The advantages of an applied overmodulation condition were demonstrated in the study performed on a phantom containing four shapes of 1.25 mM water solution of 2, 2, 6, 6-tetramethyl-1-piperidinyloxyl. It was shown that even when the overmodulated reference spectrum was used in the deconvolution procedure, as well as the projection itself, the phantom shapes reconstructed as images directly correspond to those obtained in undermodulation conditions. It was shown that the best SNR of the reconstructed images is expected for the modulation amplitude close to 1/3 of the projection linewidth, which is defined as the distance from the first maximum to the last minimum of the gradient-broadened spectrum. For higher modulation amplitude, the SNR of the reconstructed image is decreased, even if the SNR of the measured projection is increased.
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Affiliation(s)
- Krzysztof Tadyszak
- NanoBioMedical Centre, Adam Mickiewicz University, ul. Umultowska 85, 61614, Poznań, Poland
| | - Agnieszka Boś-Liedke
- NanoBioMedical Centre, Adam Mickiewicz University, ul. Umultowska 85, 61614, Poznań, Poland
- Department of Medical Physics, Faculty of Physics, Adam Mickiewicz University, ul. Umultowska 85, 61614, Poznań, Poland
| | - Jan Jurga
- Laboratory of EPR Tomography, Poznań University of Technology, ul. Piotrowo 3, 60965, Poznań, Poland
- noviLET, ul. Naramowicka 232, PL, 61611, Poznań, Poland
| | - Mikołaj Baranowski
- Department of Physics, Faculty of Physics, Adam Mickiewicz University, ul. Umultowska 85, PL, 61614, Poznań, Poland
- noviLET, ul. Naramowicka 232, PL, 61611, Poznań, Poland
| | - Radosław Mrówczyński
- NanoBioMedical Centre, Adam Mickiewicz University, ul. Umultowska 85, 61614, Poznań, Poland
| | - Wojciech Chlewicki
- Faculty of Electrical Engineering, West Pomeranian University of Technology, al. Piastów 17, 70-310, Szczecin, Poland
- noviLET, ul. Naramowicka 232, PL, 61611, Poznań, Poland
| | - Stefan Jurga
- NanoBioMedical Centre, Adam Mickiewicz University, ul. Umultowska 85, 61614, Poznań, Poland
- Department of Macromolecular Physics, Faculty of Physics, Adam Mickiewicz University, ul. Romana Maya 1, 61371, Poznań, Poland
| | - Tomasz Czechowski
- NanoBioMedical Centre, Adam Mickiewicz University, ul. Umultowska 85, 61614, Poznań, Poland
- Laboratory of EPR Tomography, Poznań University of Technology, ul. Piotrowo 3, 60965, Poznań, Poland
- noviLET, ul. Naramowicka 232, PL, 61611, Poznań, Poland
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16
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Enomoto A, Hirata H, Matsumoto S, Saito K, Subramanian S, Krishna MC, Devasahayam N. Four-channel surface coil array for 300-MHz pulsed EPR imaging: proof-of-concept experiments. Magn Reson Med 2015; 71:853-8. [PMID: 23532721 DOI: 10.1002/mrm.24702] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Time-domain electron paramagnetic resonance imaging is currently a useful preclinical molecular imaging modality in experimental animals such as mice and is capable of quantitatively mapping hypoxia in tumor implants. The microseconds range relaxation times (T1 and T2) of paramagnetic tracers and the large bandwidths (tens of MHz) to be excited by electron paramagnetic resonance pulses for spatial encoding makes imaging of large objects a challenging task. The possibility of using multiple array coils to permit studies on large sized object is the purpose of the present work. Toward this end, the use of planar array coils in different configurations to image larger objects than cannot be fully covered by a single resonator element is explored. Multiple circular surface coils, which are arranged in a plane or at suitable angles mimicking a volume resonator, are used in imaging a phantom and a tumor-bearing mouse leg. The image was formed by combining the images collected from the individual coils with suitable scaling. The results support such a possibility. By multiplexing or interleaving the measurements from each element of such array resonators, one can scale up the size of the subject and at the same time reduce the radiofrequency power requirements and increase the sensitivity.
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Affiliation(s)
- Ayano Enomoto
- Division of Bioengineering and Bioinformatics, Graduate School of Information Science and Technology, Hokkaido University, Sapporo, Hokkaido, Japan
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17
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Abstract
Rapid-scan electron paramagnetic resonance is based on continuous direct detection of the spin response as the magnetic field is scanned upfield and downfield through resonance thousands of times per second. The method provides improved signal-to-noise for a wide range of samples, including rapidly tumbling and immobilized radicals. This chapter provides an introduction to the method and practical examples of implementation for organic radicals.
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Affiliation(s)
- Sandra S Eaton
- Department of Chemistry and Biochemistry, University of Denver, Denver, Colorado, USA
| | - Gareth R Eaton
- Department of Chemistry and Biochemistry, University of Denver, Denver, Colorado, USA.
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18
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Czechowski T, Chlewicki W, Baranowski M, Jurga K, Szczepanik P, Szulc P, Tadyszak K, Kedzia P, Szostak M, Malinowski P, Wosinski S, Prukala W, Jurga J. Two-dimensional EPR imaging with the rapid scan and rotated magnetic field gradient. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2014; 248:126-30. [PMID: 25442781 DOI: 10.1016/j.jmr.2014.09.022] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2014] [Revised: 07/13/2014] [Accepted: 09/23/2014] [Indexed: 05/12/2023]
Abstract
A new method for fast 2D Electron Paramagnetic Resonance Imaging (EPRI) is presented. To reduce the time of projections acquisition we propose to combine rapid scan of Zeeman magnetic field using high frequency sinusoidal modulation with simultaneously applied magnetic field gradient, whose orientation is changed at low frequency. The correctness of the method is confirmed by studies carried out on a phantom consisting of two LiPc samples. The images from the acquired data are reconstructed using iterative algorithms. The proposed method allows to reduce the image acquisition time up to 10 ms for 2D EPRI, and to detect the sinogram with infinitesimal angular step between projections.
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Affiliation(s)
- T Czechowski
- Laboratory of EPR Tomography, Poznan University of Technology, 60-965 Poznan, Poland.
| | - W Chlewicki
- Laboratory of EPR Tomography, Poznan University of Technology, 60-965 Poznan, Poland; Faculty of Electrical Engineering, West Pomeranian University of Technology, 70-310 Szczecin, Poland
| | - M Baranowski
- Laboratory of EPR Tomography, Poznan University of Technology, 60-965 Poznan, Poland; Department of Physics, Adam Mickiewicz University, 61-614 Poznan, Poland
| | - K Jurga
- Laboratory of EPR Tomography, Poznan University of Technology, 60-965 Poznan, Poland
| | - P Szczepanik
- Laboratory of EPR Tomography, Poznan University of Technology, 60-965 Poznan, Poland
| | - P Szulc
- Laboratory of EPR Tomography, Poznan University of Technology, 60-965 Poznan, Poland
| | - K Tadyszak
- NanoBioMedical Centre, Adam Mickiewicz University, ul. Umultowska 14, PL 61614 Poznan, Poland
| | - P Kedzia
- Laboratory of EPR Tomography, Poznan University of Technology, 60-965 Poznan, Poland
| | - M Szostak
- Laboratory of EPR Tomography, Poznan University of Technology, 60-965 Poznan, Poland
| | - P Malinowski
- Laboratory of EPR Tomography, Poznan University of Technology, 60-965 Poznan, Poland
| | - S Wosinski
- Laboratory of EPR Tomography, Poznan University of Technology, 60-965 Poznan, Poland
| | - W Prukala
- Laboratory of EPR Tomography, Poznan University of Technology, 60-965 Poznan, Poland; Department of Organometalic Chemistry, Adam Mickiewicz University, 60-780 Poznan, Poland
| | - J Jurga
- Laboratory of EPR Tomography, Poznan University of Technology, 60-965 Poznan, Poland
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19
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Czechowski T, Chlewicki W, Baranowski M, Jurga K, Szczepanik P, Szulc P, Kedzia P, Szostak M, Malinowski P, Wosinski S, Prukala W, Jurga J. Two-dimensional spectral-spatial EPR imaging with the rapid scan and modulated magnetic field gradient. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2014; 243:1-7. [PMID: 24705409 DOI: 10.1016/j.jmr.2014.03.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Revised: 03/03/2014] [Accepted: 03/04/2014] [Indexed: 06/03/2023]
Abstract
A new method for fast spectral-spatial electron paramagnetic resonance imaging (EPRI) is presented. To reduce the time of projections acquisition we propose to combine rapid scan of Zeeman magnetic field using high frequency sinusoidal modulation with simultaneously applied magnetic field gradients, whose amplitude is modulated at low frequency. The correctness of the method is confirmed by studies carried out on a phantom consisting of two LiPc samples. The spectral-spatial images from the acquired data are reconstructed using iterative algorithms. The proposed method allows to acquire the spectral-spatial image with 800 projections at 200ms.
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Affiliation(s)
- T Czechowski
- Laboratory of EPR Tomography, Poznan University of Technology, 60-965 Poznan, Poland.
| | - W Chlewicki
- Laboratory of EPR Tomography, Poznan University of Technology, 60-965 Poznan, Poland; Faculty of Electrical Engineering, West Pomeranian University of Technology, 70-310 Szczecin, Poland
| | - M Baranowski
- Laboratory of EPR Tomography, Poznan University of Technology, 60-965 Poznan, Poland; Department of Physics, Adam Mickiewicz University, 61-614 Poznan, Poland
| | - K Jurga
- Laboratory of EPR Tomography, Poznan University of Technology, 60-965 Poznan, Poland
| | - P Szczepanik
- Laboratory of EPR Tomography, Poznan University of Technology, 60-965 Poznan, Poland
| | - P Szulc
- Laboratory of EPR Tomography, Poznan University of Technology, 60-965 Poznan, Poland
| | - P Kedzia
- Laboratory of EPR Tomography, Poznan University of Technology, 60-965 Poznan, Poland
| | - M Szostak
- Laboratory of EPR Tomography, Poznan University of Technology, 60-965 Poznan, Poland
| | - P Malinowski
- Laboratory of EPR Tomography, Poznan University of Technology, 60-965 Poznan, Poland
| | - S Wosinski
- Laboratory of EPR Tomography, Poznan University of Technology, 60-965 Poznan, Poland
| | - W Prukala
- Laboratory of EPR Tomography, Poznan University of Technology, 60-965 Poznan, Poland; Department of Organometallic Chemistry, Adam Mickiewicz University, 60-780 Poznan, Poland
| | - J Jurga
- Laboratory of EPR Tomography, Poznan University of Technology, 60-965 Poznan, Poland
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20
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Johnson DH, Ahmad R, He G, Samouilov A, Zweier JL. Compressed sensing of spatial electron paramagnetic resonance imaging. Magn Reson Med 2013; 72:893-901. [PMID: 24123102 DOI: 10.1002/mrm.24966] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2013] [Revised: 07/26/2013] [Accepted: 09/03/2013] [Indexed: 12/20/2022]
Abstract
PURPOSE To improve image quality and reduce data requirements for spatial electron paramagnetic resonance imaging (EPRI) by developing a novel reconstruction approach using compressed sensing (CS). METHODS EPRI is posed as an optimization problem, which is solved using regularized least-squares with sparsity promoting penalty terms, consisting of the l1 norms of the image itself and the total variation of the image. Pseudo-random sampling was employed to facilitate recovery of the sparse signal. The reconstruction was compared with the traditional filtered back-projection reconstruction for simulations, phantoms, isolated rat hearts, and mouse gastrointestinal (GI) tracts labeled with paramagnetic probes. RESULTS A combination of pseudo-random sampling and CS was able to generate high-fidelity EPR images at high acceleration rates. For three-dimensional (3D) phantom imaging, CS-based EPRI showed little visual degradation at nine-fold acceleration. In rat heart datasets, CS-based EPRI produced high quality images with eight-fold acceleration. A high resolution mouse GI tract reconstruction demonstrated a visual improvement in spatial resolution and a doubling in signal-to-noise ratio (SNR). CONCLUSION A novel 3D EPRI reconstruction using compressed sensing was developed and offers superior SNR and reduced artifacts from highly undersampled data.
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Affiliation(s)
- David H Johnson
- Center for Biomedical EPR Spectroscopy and Imaging, Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA
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21
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Johnson DH, Ahmad R, Liu Y, Chen Z, Samouilov A, Zweier JL. Uniform spinning sampling gradient electron paramagnetic resonance imaging. Magn Reson Med 2013; 71:893-900. [PMID: 23475830 DOI: 10.1002/mrm.24712] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
PURPOSE To improve the quality and speed of electron paramagnetic resonance imaging (EPRI) acquisition by combining a uniform sampling distribution with spinning gradient acquisition. THEORY AND METHODS A uniform sampling distribution was derived for spinning gradient EPRI acquisition (uniform spinning sampling, USS) and compared to the existing (equilinear spinning sampling, ESS) acquisition strategy. Novel corrections were introduced to reduce artifacts in experimental data. RESULTS Simulations demonstrated that USS puts an equal number of projections near each axis whereas ESS puts excessive projections at one axis, wasting acquisition time. Artifact corrections added to the magnetic gradient waveforms reduced noise and correlation between projections. USS images had higher SNR (85.9 ± 0.8 vs. 56.2 ± 0.8) and lower mean-squared error than ESS images. The quality of the USS images did not vary with the magnetic gradient orientation, in contrast to ESS images. The quality of rat heart images was improved using USS compared to that with ESS or traditional fast-scan acquisitions. CONCLUSION A novel EPRI acquisition which combines spinning gradient acquisition with a uniform sampling distribution was developed. This USS spinning gradient acquisition offers superior SNR and reduced artifacts compared to prior methods enabling potential improvements in speed and quality of EPR imaging in biological applications.
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Affiliation(s)
- David H Johnson
- Center for Biomedical EPR Spectroscopy and Imaging, Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, Ohio, USA
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22
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Epel, B, Halpern H. Electron paramagnetic resonance oxygen imaging in vivo. ELECTRON PARAMAGNETIC RESONANCE 2012. [DOI: 10.1039/9781849734837-00180] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
This review covers the last 15 years of the development of EPR in vivo oxygen imaging. During this time, a number of major technological and methodological advances have taken place. Narrow line width, long relaxation time, and non-toxic triaryl methyl radicals were introduced in the late 1990s. These not only improved continuous wave (CW) imaging, but also enabled the application of pulse EPR imaging to animals. Recent developments in pulse technology have brought an order of magnitude increase in image acquisition speed, enhancement of sensitivity, and considerable improvement in the precision and accuracy of oxygen measurements. Consequently, pulse methods take up a significant part of this review.
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Affiliation(s)
- Boris Epel,
- Center for EPR Imaging in vivo Physiology the University of Chicago, Department of Radiation and Cellular Oncology (MC 1105), Chicago Illinois 60637
| | - Howard Halpern
- Center for EPR Imaging in vivo Physiology the University of Chicago, Department of Radiation and Cellular Oncology (MC 1105), Chicago Illinois 60637
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23
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Palmer J, Potter L, Johnson D, Zweier J, Ahmad R. Dual-scan acquisition for accelerated continuous-wave EPR oximetry. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2012; 222:53-58. [PMID: 22820009 PMCID: PMC3423522 DOI: 10.1016/j.jmr.2012.05.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2012] [Revised: 05/11/2012] [Accepted: 05/26/2012] [Indexed: 06/01/2023]
Abstract
Statistical analysis reveals that, given a fixed acquisition time, linewidth (and thus pO(2)) can be more precisely determined from multiple scans with different modulation amplitudes and sweep widths than from a single-scan. For a Lorentzian lineshape and an unknown but spatially uniform modulation amplitude, the analysis suggests the use of two scans, each occupying half of the total acquisition time. We term this mode of scanning as dual-scan acquisition. For unknown linewidths in a range [Γ(min), Γ(max)], practical guidelines are provided for selecting the modulation amplitude and sweep width for each dual-scan component. Following these guidelines can allow for a 3-4 times reduction in spectroscopic acquisition time versus an optimized single-scan, without requiring hardware modifications. Findings are experimentally verified using L-band spectroscopy with an oxygen-sensitive particulate probe.
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Affiliation(s)
- J. Palmer
- Department of Electrical and Computer Engineering, The Ohio State University, Columbus, OH 43210, USA
| | - L.C. Potter
- Department of Electrical and Computer Engineering, The Ohio State University, Columbus, OH 43210, USA
| | - D.H. Johnson
- Davis Heart and Lung Research Institute, Department of Internal Medicine, The Ohio State University, Columbus, OH 43210, USA
| | - J.L. Zweier
- Davis Heart and Lung Research Institute, Department of Internal Medicine, The Ohio State University, Columbus, OH 43210, USA
| | - R. Ahmad
- Davis Heart and Lung Research Institute, Department of Internal Medicine, The Ohio State University, Columbus, OH 43210, USA
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Epel B, Sundramoorthy SV, Barth ED, Mailer C, Halpern HJ. Comparison of 250 MHz electron spin echo and continuous wave oxygen EPR imaging methods for in vivo applications. Med Phys 2011; 38:2045-52. [PMID: 21626937 DOI: 10.1118/1.3555297] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE The authors compare two electron paramagnetic resonance imaging modalities at 250 MHz to determine advantages and disadvantages of those modalities for in vivo oxygen imaging. METHODS Electron spin echo (ESE) and continuous wave (CW) methodologies were used to obtain three-dimensional images of a narrow linewidth, water soluble, nontoxic oxygen-sensitive trityl molecule OX063 in vitro and in vivo. The authors also examined sequential images obtained from the same animal injected intravenously with trityl spin probe to determine temporal stability of methodologies. RESULTS A study of phantoms with different oxygen concentrations revealed a threefold advantage of the ESE methodology in terms of reduced imaging time and more precise oxygen resolution for samples with less than 70 torr oxygen partial pressure. Above 100 torr, CW performed better. The images produced by both methodologies showed pO2 distributions with similar mean values. However, ESE images demonstrated superior performance in low pO2 regions while missing voxels in high pO2 regions. CONCLUSIONS ESE and CW have different areas of applicability. ESE is superior for hypoxia studies in tumors.
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Affiliation(s)
- Boris Epel
- Department of Radiation and Cellular Oncology, Center for EPR Imaging In Vivo Physiology, University of Chicago, MC1105, 5841 South Maryland Avenue, Chicago, Illinois 60637, USA.
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Tseitlin M, Rinard GA, Quine RW, Eaton SS, Eaton GR. Deconvolution of sinusoidal rapid EPR scans. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2011; 208:279-83. [PMID: 21163677 PMCID: PMC3097533 DOI: 10.1016/j.jmr.2010.11.015] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2010] [Revised: 11/04/2010] [Accepted: 11/19/2010] [Indexed: 05/05/2023]
Abstract
In rapid scan EPR the magnetic field is scanned through the signal in a time that is short relative to electron spin relaxation times. Previously it was shown that the slow-scan lineshape could be recovered from triangular rapid scans by Fourier deconvolution. In this paper a general Fourier deconvolution method is described and demonstrated to recover the slow-scan lineshape from sinusoidal rapid scans. Since an analytical expression for the Fourier transform of the driving function for a sinusoidal scan was not readily apparent, a numerical method was developed to do the deconvolution. The slow scan EPR lineshapes recovered from rapid triangular and sinusoidal scans are in excellent agreement for lithium phthalocyanine, a trityl radical, and the nitroxyl radical, tempone. The availability of a method to deconvolute sinusoidal rapid scans makes it possible to scan faster than is feasible for triangular scans because of hardware limitations on triangular scans.
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Affiliation(s)
- Mark Tseitlin
- Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80208
| | - George A. Rinard
- School of Engineering and Computer Science, University of Denver, Denver, CO 80208
| | - Richard W. Quine
- School of Engineering and Computer Science, University of Denver, Denver, CO 80208
| | - Sandra S. Eaton
- Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80208
| | - Gareth R. Eaton
- Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80208
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Abstract
Nitroxyl contrast agents (nitroxyl radicals, also known as nitroxide) are paramagnetic species, which can react with reactive oxygen species (ROS) to lose paramagnetism to be diamagnetic species. The paramagnetic nitroxyl radical forms can be detected by using electron paramagnetic resonance imaging (EPRI), Overhauser MRI (OMRI), or MRI. The time course of in vivo image intensity induced by paramagnetic redox-sensitive contrast agent can give tissue redox information, which is the so-called redox imaging technique. The redox imaging technique employing a blood-brain barrier permeable nitroxyl contrast agent can be applied to analyze the pathophysiological functions in the brain. A brief theory of redox imaging techniques is described, and applications of redox imaging techniques to brain are introduced.
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Seifi P, Epel B, Mailer C, Halpern HJ. Multiple-stepped Zeeman field offset method applied in acquiring enhanced resolution spin-echo electron paramagnetic resonance images. Med Phys 2010; 37:5412-20. [PMID: 21089777 DOI: 10.1118/1.3475936] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE Electron paramagnetic resonance (EPR) imaging techniques provide quantitative in vivo oxygen distribution images. Time-domain techniques including electron spin echo (ESE) imaging have been under study in recent years for their robustness and promising new features. One of the limitations of ESE imaging addressed here is the finite acquisition frequency bandwidth, which imposes limits on applied magnetic field gradients and the resulting image spatial resolution. In order to improve the image spatial resolution, we have extended the effective frequency bandwidth of the imaging system by acquiring projections at multiple Zeeman magnetic field offsets and combining them to restore complete projections obtained with more uniform frequency response, resulting in higher quality images. METHODS In multiple-stepped magnetic field or multi-B scheme, every projection of the three dimensional object is acquired at different main or Zeeman magnetic field (B) offset values. The data from field offset steps are combined, normalizing to the imaging system frequency acquisition window function, a sensitivity profile, to restore the complete projection. A multipurpose pulse EPR imager and phantoms containing the same type of spin probe (OX063H) used in routine animal imaging were also used in this study. RESULTS Using the multi-B method, we were able to acquire images of our phantoms with enhanced spatial resolution compared to the conventional ESE approach. Compared to standard single-B ESE images, the T2 resolutions of multi-B images were superior using a high spatial-resolution regime. Image artifacts present in high-gradient single-B ESE images are also substantially reduced using in the multi-B scheme. CONCLUSIONS The multi-B method is less susceptible to instrumental limitations for larger gradient fields and acquiring images with higher spatial resolution better overall quality, without the need to alter the existing pulse ESE image acquisition hardware.
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Affiliation(s)
- Payam Seifi
- Department of Radiation and Cellular Oncology, Center for EPR Imaging In Vivo Physiology, University of Chicago, Chicago, Illinois 60637, USA
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Quine RW, Czechowski T, Eaton GR. A Linear Magnetic Field Scan Driver. CONCEPTS IN MAGNETIC RESONANCE. PART B, MAGNETIC RESONANCE ENGINEERING 2009; 35B:44-58. [PMID: 19838315 PMCID: PMC2762224 DOI: 10.1002/cmr.b.20128] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
A linear magnetic field scan driver was developed to provide a rapidly scanning magnetic field for use in electron paramagnetic resonance (EPR) spectroscopy. The driver consists of two parts: a digitally synthesized ramp waveform generator and a power amplifier to drive the magnetic field coils. Additionally, the driver provides a trigger signal to a data collection digitizer that is synchronized to the ramp waveform. The driver can also drive an arbitrary current waveform supplied from an external source. The waveform generator is computer controlled through a serial data interface. Additional functions are controlled by the user from the driver front panel. The frequency and amplitude of the waveform are each separately controlled with 12-bit resolution (one part in 4,096). Several versions of the driver have been built with different frequency and amplitude ranges. Frequencies range from 500 to 20,000 Hz. Field sweep amplitudes range up to 80 G(pp). This article also gives a brief description of the field coils that are driven by the driver.
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Affiliation(s)
- Richard W Quine
- Department of Engineering, University of Denver, Denver, CO 80208
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Subramanian S, Krishna MC. DANCING WITH THE ELECTRONS: TIME-DOMAIN AND CW IN VIVO EPR IMAGING. MAGNETIC RESONANCE INSIGHTS 2008; 2:43-74. [PMID: 22025900 DOI: 10.4137/mri.s1131] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The progress in the development of imaging the distribution of unpaired electrons in living systems and the functional and the potential diagnostic dimensions of such an imaging process, using Electron Paramagnetic Resonance Imaging (EPRI), is traced from its origins with emphasis on our own work. The importance of EPR imaging stems from the fact that many paramagnetic probes show oxygen dependent spectral broadening. Assessment of in vivo oxygen concentration is an important factor in radiation oncology in treatment-planning and monitoring treatment-outcome. The emergence of narrow-line trairylmethyl based, bio-compatible spin probes has enabled the development of radiofrequency time-domain EPRI. Spectral information in time-domain EPRI can be achieved by generating a time sequence of T(2)* or T(2) weighted images. Progress in CW imaging has led to the use of rotating gradients, more recently rapid scan with direct detection, and a combination of all the three. Very low field MRI employing Dynamic Nuclear polarization (Overhauser effect) is also employed for monitoring tumor hypoxia, and re-oxygenation in vivo. We have also been working on the co-registration of MRI and time domain EPRI on mouse tumor models at 300 MHz using a specially designed resonator assembly. The mapping of the unpaired electron distribution and unraveling the spectral characteristics by using magnetic resonance in presence of stationary and rotating gradients in indeed 'dancing with the (unpaired) electrons', metaphorically speaking.
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Affiliation(s)
- Sankaran Subramanian
- Radiation Biology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
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Vikram DS, Ahmad R, Rivera BK, Kuppusamy P. Mapping of Oxygen Concentration in Biological Samples Using EPR Imaging. Isr J Chem 2008. [DOI: 10.1560/ijc.48.1.39] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Epel B, Sundramoorthy SV, Mailer C, Halpern HJ. A Versatile High Speed 250 MHz Pulse Imager for Biomedical Applications. CONCEPTS IN MAGNETIC RESONANCE. PART B, MAGNETIC RESONANCE ENGINEERING 2008; 33B:163-176. [PMID: 19924261 PMCID: PMC2778030 DOI: 10.1002/cmr.b.20119] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
A versatile 250 MHz pulse electron paramagnetic resonance (EPR) instrument for imaging of small animals is presented. Flexible design of the imager hardware and software makes it possible to use virtually any pulse EPR imaging modality. A fast pulse generation and data acquisition system based on general purpose PCI boards performs measurements with minimal additional delays. Careful design of receiver protection circuitry allowed us to achieve very high sensitivity of the instrument. In this article we demonstrate the ability of the instrument to obtain three dimensional images using the electron spin echo (ESE) and single point imaging (SPI) methods. In a phantom that contains a 1 mM solution of narrow line (16 μT, peak-to-peak) paramagnetic spin probe we achieved an acquisition time of 32 seconds per image with a fast 3D ESE imaging protocol. Using an 18 minute 3D phase relaxation (T(2e)) ESE imaging protocol in a homogeneous sample a spatial resolution of 1.4 mm and a standard deviation of T(2e) of 8.5% were achieved. When applied to in vivo imaging this precision of T(2e) determination would be equivalent to 2 torr resolution of oxygen partial pressure in animal tissues.
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Affiliation(s)
- Boris Epel
- Center for EPR Imaging In Vivo Physiology, University of Chicago, Department of Radiology Oncology, MC1105, 5841 S. Maryland Avenue, Chicago, IL 60637, USA
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