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Yang Q, Zhao J, Dreyer F, Krüger D, Chu A, Kern M, Blümich B, Anders J. A chip-based C-band ODNP platform. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2024; 358:107603. [PMID: 38142565 DOI: 10.1016/j.jmr.2023.107603] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Revised: 11/24/2023] [Accepted: 11/28/2023] [Indexed: 12/26/2023]
Abstract
In this paper, we present a chip-based C-band ODNP platform centered around an NMR-on-a-chip transceiver and a printed microwave (MW) Alderman-Grant (AG) coil with a broadband tunable frequency range of 528MHz. The printable ODNP probe is optimized for a high input-power-to-magnetic-field conversion-efficiency, achieving a measured ODNP enhancement factor of -151 at microwave power levels of 33.3dBm corresponding to 2.1W. NMR measurements with and without microwave irradiation verify the functionality and the state-of-the-art performance of the proposed ODNP platform. The wide tuning range of the system allows for indirect measurements of the EPR signal of the DNP agent by sweeping the microwave excitation frequency and recording the resulting NMR signal. This feature can, e.g., be used to detect line broadening of the DNP agent. Moreover, we demonstrate experimentally that the wide tuning range of the new ODNP platform can be used to perform multi-tone microwave excitation for further signal enhancement: Using a 10mM TEMPOL solution, we improved the enhancement by a factor of two.
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Affiliation(s)
- Qing Yang
- Institute of Smart Sensors, University of Stuttgart, Pfafenwaldring 47, Stuttgart, 70569, Germany
| | - Jianyu Zhao
- Institute of Smart Sensors, University of Stuttgart, Pfafenwaldring 47, Stuttgart, 70569, Germany
| | - Frederik Dreyer
- Institute of Smart Sensors, University of Stuttgart, Pfafenwaldring 47, Stuttgart, 70569, Germany
| | - Daniel Krüger
- Institute of Smart Sensors, University of Stuttgart, Pfafenwaldring 47, Stuttgart, 70569, Germany; John A. Paulson School of Engineering and Applied Sciences, Harvard University, 29 Oxford Street, Cambridge, 02138, United States
| | - Anh Chu
- Institute of Smart Sensors, University of Stuttgart, Pfafenwaldring 47, Stuttgart, 70569, Germany
| | - Michal Kern
- Institute of Smart Sensors, University of Stuttgart, Pfafenwaldring 47, Stuttgart, 70569, Germany
| | - Bernhard Blümich
- Institut für Technische und Makromolekulare Chemie, RWTH Aachen University, Worringerweg 2, Aachen, 52074, Germany
| | - Jens Anders
- Institute of Smart Sensors, University of Stuttgart, Pfafenwaldring 47, Stuttgart, 70569, Germany; Center for Integrated Quantum Science and Technology (IQ(ST)), Stuttgart, Germany; Institute for Microelectronics Stuttgart (IMS CHIPS), Stuttgart, Germany.
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2
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O'Connell RC, Tseytlin O, Bobko AA, Eubank TD, Tseytlin M. Rapid scan EPR: Automated digital resonator control for low-latency data acquisition. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2022; 345:107308. [PMID: 36356489 PMCID: PMC10266206 DOI: 10.1016/j.jmr.2022.107308] [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: 08/20/2022] [Revised: 10/05/2022] [Accepted: 10/06/2022] [Indexed: 06/05/2023]
Abstract
Automation has become an essential component of modern scientific instruments which often capture large amounts of complex dynamic data. Algorithms are developed to read multiple sensors in parallel with data acquisition and to adjust instrumental parameters on the fly. Decisions are made on a time scale unattainable to the human operator. In addition to speed, automation reduces human error, improves the reproducibility of experiments, and improves the reliability of acquired data. An automatic digital control (ADiC) was developed to reliably sustain critical coupling of a resonator over a wide range of time-varying loading conditions. The ADiC uses the computational power of a microcontroller that directly communicates with all system components independent of a personal computer (PC). The PC initiates resonator tuning and coupling by sending a command to MC via serial port. After receiving the command, ADiC establishes critical coupling conditions within approximately 5 ms. A printed circuit board resonator was designed to permit digital control. The performance of the resonator together with the ADiC was evaluated by varying the resonator loading from empty to heavily loaded. For the loading, samples containing aqueous sodium chloride that strongly absorb electromagnetic waves were used. A previously reported rapid scan (RS) electron paramagnetic resonance (EPR) imaging instrument was upgraded by the incorporation of ADiC. RS spectra and an in vivo image of oxygen in a mouse tumor model have been acquired using the upgraded system. ADiC robustly sustained critical coupling of the resonator to the transmission line during these measurements. The design implemented in this study can be used in slow-scan and pulsed EPR with modifications.
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Affiliation(s)
- Ryan C O'Connell
- Department of Biochemistry and Molecular Medicine, 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
| | - Oxana Tseytlin
- Department of Biochemistry and Molecular Medicine, 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
- Department of Biochemistry and Molecular Medicine, 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
| | - 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 and Cell Biology, West Virginia University, Morgantown, WV 26506, USA
| | - Mark Tseytlin
- Department of Biochemistry and Molecular Medicine, West Virginia University, Morgantown, WV 26506, USA; West Virginia University Cancer Institute, 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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3
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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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Noninvasive Diagnosis of the Mitochondrial Function of Doxorubicin-Induced Cardiomyopathy Using In Vivo Dynamic Nuclear Polarization-Magnetic Resonance Imaging. Antioxidants (Basel) 2022; 11:antiox11081454. [PMID: 35892655 PMCID: PMC9331045 DOI: 10.3390/antiox11081454] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2022] [Revised: 07/18/2022] [Accepted: 07/25/2022] [Indexed: 02/01/2023] Open
Abstract
Doxorubicin (DOX) induces dose-dependent cardiotoxicity via oxidative stress and abnormal mitochondrial function in the myocardium. Therefore, a noninvasive in vivo imaging procedure for monitoring the redox status of the heart may aid in monitoring diseases and developing treatments. However, an appropriate technique has yet to be developed. In this study, we demonstrate a technique for detecting and visualizing the redox status of the heart using in vivo dynamic nuclear polarization–magnetic resonance imaging (DNP–MRI) with 3-carbamoyl-PROXYL (CmP) as a molecular imaging probe. Male C57BL/6N mice were administered DOX (20 mg/kg) or saline. DNP–MRI clearly showed a slower DNP signal reduction in the DOX group than in the control group. Importantly, the difference in the DNP signal reduction rate between the two groups occurred earlier than that detected by physiological examination or clinical symptoms. In an in vitro experiment, KCN (an inhibitor of complex IV in the mitochondrial electron transport chain) and DOX inhibited the electron paramagnetic resonance change in H9c2 cardiomyocytes, suggesting that the redox metabolism of CmP in the myocardium is mitochondrion-dependent. Therefore, this molecular imaging technique has the potential to monitor the dynamics of redox metabolic changes in DOX-induced cardiomyopathy and facilitate an early diagnosis of this condition.
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Enomoto A, Ichikawa K. Dual channel EPR excitation coil array for Overhauser-enhanced MRI. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2021; 323:106890. [PMID: 33352434 DOI: 10.1016/j.jmr.2020.106890] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Revised: 12/05/2020] [Accepted: 12/07/2020] [Indexed: 06/12/2023]
Abstract
This article describes the development of a two-channel surface coil array for Overhauser-enhanced magnetic resonance imaging (OMRI) with the aim of extending the visualization area. The surface coil array consists of two independent surface coil resonators and PIN-diode switches. We utilized the PIN-diode switch to decouple the surface coils. OMRI measurement using a surface coil array was sequentially performed by switching the channels. To evaluate the effectiveness of the surface coil array, we demonstrated OMRI measurements using a phantom filled with nitroxide solution. In addition, in vivo OMRI imaging with a mouse was performed to demonstrate the applicability of our surface coil array to in vivo measurements. As a result, the visualization area obtained with our surface coil array was extended approximately 2-fold compared to the conventional single surface coil. Furthermore, we showed that in vivo imaging with the surface coil array was possible. These results indicate that the surface coil array could enhance the applicability of OMRI imaging.
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Affiliation(s)
- Ayano Enomoto
- Department of Biophysical Chemistry, Faculty of Pharmaceutical Sciences, Nagasaki International University, 2825-7 Huis Ten Bosch, Sasebo, Nagasaki 859-3298, Japan.
| | - Kazuhiro Ichikawa
- Department of Biophysical Chemistry, Faculty of Pharmaceutical Sciences, Nagasaki International University, 2825-7 Huis Ten Bosch, Sasebo, Nagasaki 859-3298, Japan
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6
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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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7
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Takahashi W, Bobko AA, Dhimitruka I, Hirata H, Zweier JL, Samouilov A, Khramtsov VV. Proton-Electron Double-Resonance Imaging of pH using phosphonated trityl probe. APPLIED MAGNETIC RESONANCE 2014; 45:817-826. [PMID: 25530673 PMCID: PMC4268155 DOI: 10.1007/s00723-014-0570-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Variable Radio Frequency Proton-Electron Double-Resonance Imaging (VRF PEDRI) enables extracting a functional map from a limited number of images acquired at pre-selected EPR frequencies using specifically designed paramagnetic probes with high quality spatial resolution and short acquisition times. In this work we explored potential of VRF PEDRI for pH mapping of aqueous samples using recently synthesized pH-sensitive phosphonated trityl radical, pTR. The ratio of Overhauser enhancements measured at each pixel at two different excitation frequencies corresponding to the resonances of protonated and deprotonated forms of pTR probe allows for a pH map extraction. Long relaxation times of pTR allow for pH mapping at EPR irradiation power as low as 1.25 W during 130 s acquisition time with spatial resolution of about 1 mm. This is particularly important for in vivo applications enabling one to avoid sample overheating by reducing RF power deposition.
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Affiliation(s)
- Wataru Takahashi
- Division of Pulmonary, Allergy, Critical Care & Sleep Medicine, Department of Internal Medicine and Dorothy M. Davis Heart & Lung Research Institute, The Ohio State University, Columbus, OH, USA ; Division of Bioengineering and Bioinformatics, Graduate School of Information Science and Technology, Hokkaido University, Sapporo, Japan
| | - Andrey A Bobko
- Division of Pulmonary, Allergy, Critical Care & Sleep Medicine, Department of Internal Medicine and Dorothy M. Davis Heart & Lung Research Institute, The Ohio State University, Columbus, OH, USA
| | - Ilirian Dhimitruka
- Division of Pulmonary, Allergy, Critical Care & Sleep Medicine, Department of Internal Medicine and Dorothy M. Davis Heart & Lung Research Institute, The Ohio State University, Columbus, OH, USA
| | - Hiroshi Hirata
- Division of Bioengineering and Bioinformatics, Graduate School of Information Science and Technology, Hokkaido University, Sapporo, Japan
| | - Jay L Zweier
- Division of Cardiology and Dorothy M. Davis Heart & Lung Research Institute, Department of Internal Medicine, The Ohio State University, Columbus, OH, USA
| | - Alexandre Samouilov
- Division of Cardiology and Dorothy M. Davis Heart & Lung Research Institute, Department of Internal Medicine, The Ohio State University, Columbus, OH, USA
| | - Valery V Khramtsov
- Division of Pulmonary, Allergy, Critical Care & Sleep Medicine, Department of Internal Medicine and Dorothy M. Davis Heart & Lung Research Institute, The Ohio State University, Columbus, OH, USA
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Sundramoorthy SV, Epel B, Halpern HJ. Orthogonal resonators for pulse in vivo electron paramagnetic imaging at 250 MHz. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2014; 240:45-51. [PMID: 24530507 PMCID: PMC3974126 DOI: 10.1016/j.jmr.2013.12.015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2013] [Revised: 12/03/2013] [Accepted: 12/27/2013] [Indexed: 05/13/2023]
Abstract
A 250 MHz bimodal resonator with a 19 mm internal diameter for in vivo pulse electron paramagnetic resonance (EPR) imaging is presented. Two separate coaxial cylindrical resonators inserted one into another were used for excitation and detection. The Alderman-Grant excitation resonator (AGR) showed the highest efficiency among all the excitation resonators tested. The magnetic field of AGR is confined to the volume of the detection resonator, which results in highly efficient use of the radio frequency power. A slotted inner single loop single gap resonator (SLSG LGR), coaxial to the AGR, was used for signal detection. The resulting bimodal resonator (AG/LGR) has two mutually orthogonal magnetic field modes; one of them has the magnetic field in the axial direction. The resonator built in our laboratory achieved 40 dB isolation over 20 MHz bandwidth with quality factors of detection and excitation resonators of 36 and 11 respectively. Considerable improvement of the B1 homogeneity and EPR image quality in comparison with reflection loop-gap resonator of similar size and volume was observed.
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Affiliation(s)
- Subramanian V Sundramoorthy
- Center for EPR Imaging In Vivo Physiology, Department of Radiation and Cellular Oncology, University of Chicago, Chicago, IL 60637, USA
| | - Boris Epel
- Center for EPR Imaging In Vivo Physiology, Department of Radiation and Cellular Oncology, University of Chicago, Chicago, IL 60637, USA.
| | - Howard J Halpern
- Center for EPR Imaging In Vivo Physiology, Department of Radiation and Cellular Oncology, University of Chicago, Chicago, IL 60637, USA.
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9
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Samouilov A, Efimova OV, Bobko AA, Sun Z, Petryakov S, Eubank TD, Trofimov DG, Kirilyuk IA, Grigor'ev IA, Takahashi W, Zweier JL, Khramtsov VV. In vivo proton-electron double-resonance imaging of extracellular tumor pH using an advanced nitroxide probe. Anal Chem 2014; 86:1045-52. [PMID: 24372284 DOI: 10.1021/ac402230h] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A variable radio frequency proton-electron double-resonance imaging (VRF PEDRI) approach for pH mapping of aqueous samples has been recently developed (Efimova et al. J. Magn. Reson. 2011, 209, 227-232). A pH map is extracted from two PEDRI acquisitions performed at electron paramagnetic resonance (EPR) frequencies of protonated and unprotonated forms of a pH-sensitive probe. To translate VRF PEDRI to an in vivo setting, an advanced pH probe was synthesized. Probe deuteration resulted in a narrow spectral line of 1.2 G compared to a nondeuterated analogue line width of 2.1 G allowing for an increase of Overhauser enhancements and reduction in rf power deposition. Binding of the probe to the cell-impermeable tripeptide, glutathione (GSH), allows for targeting to extracellular tissue space for monitoring extracellular tumor acidosis, a prognostic factor in tumor pathophysiology. The probe demonstrated pH sensitivity in the 5.8-7.8 range, optimum for measurement of acidic extracellular tumor pH (pH(e)). In vivo VRF PEDRI was performed on Met-1 tumor-bearing mice. Compared to normal mammary glands with a neutral mean pH(e) (7.1 ± 0.1), we observed broader pH distribution with acidic mean pH(e) (6.8 ± 0.1) in tumor tissue. In summary, VRF PEDRI in combination with a newly developed pH probe provides an analytical approach for spatially resolved noninvasive pHe monitoring, in vivo.
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Affiliation(s)
- Alexandre Samouilov
- The Dorothy M. Davis Heart and Lung Research Institute: ‡Division of Pulmonary, Allergy, Critical Care, and Sleep Medicine, and §Division of Cardiovascular Medicine, Department of Internal Medicine, The Ohio State University , Columbus, Ohio 43210, United States
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10
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Siaw TA, Walker SA, Armstrong BD, Han SI. Inductively coupled NMR probe for versatile dynamic nuclear polarization operation at 7 T: observation of 61 ± 2% ¹H polarization at 4 K. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2012; 221:5-10. [PMID: 22743536 DOI: 10.1016/j.jmr.2012.05.017] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2012] [Revised: 05/23/2012] [Accepted: 05/29/2012] [Indexed: 06/01/2023]
Abstract
We have performed dynamic nuclear polarization (DNP) experiments at liquid helium temperatures using a low-power (<70 mW) solid-state diode microwave source at 200 GHz-the electron paramagnetic resonance frequency of stable radicals at 7 T. We employed a home-built Alderman-Grant probe for the detection of ¹H NMR signal at 300 MHz, as such coils are well suited for higher frequency NMR detection. The Alderman-Grant coil is inductively coupled to the rest of the radiofrequency (rf) circuit, whose design allows probe components to be placed away from the sample area, and also enables easy switching of coils with different diameters and resonance frequencies. We have tested our DNP instrument on a frozen nitroxide model system consisting of 4-Amino TEMPO dissolved in a glycerol:water mixture. The largest nuclear spin polarization observed was 61 ± 2% with a sample containing 20 mM 4-Amino TEMPO dissolved in deuterated glycerol (d-glycerol):D₂O:H₂O (50:40:10), amounting to record polarization measured to date at an easily amenable temperature of 4 K.
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Affiliation(s)
- Ting Ann Siaw
- Department of Chemical Engineering, University of California Santa Barbara, Santa Barbara, CA 93106, USA
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11
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Sun Z, Li H, Petryakov S, Samouilov A, Zweier JL. In vivo proton electron double resonance imaging of mice with fast spin echo pulse sequence. J Magn Reson Imaging 2011; 35:471-5. [PMID: 22147559 DOI: 10.1002/jmri.22874] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2011] [Accepted: 10/05/2011] [Indexed: 11/09/2022] Open
Abstract
PURPOSE To develop and evaluate a two-dimensional (2D) fast spin echo (FSE) pulse sequence for enhancing temporal resolution and reducing tissue heating for in vivo proton electron double resonance imaging (PEDRI) of mice. MATERIALS AND METHODS A four-compartment phantom containing 2 mM TEMPONE was imaged at 20.1 mT using 2D FSE-PEDRI and regular gradient echo (GRE)-PEDRI pulse sequences. Control mice were infused with TEMPONE over ~1 min followed by time-course imaging using the 2D FSE-PEDRI sequence at intervals of 10-30 s between image acquisitions. The average signal intensity from the time-course images was analyzed using a first-order kinetics model. RESULTS Phantom experiments demonstrated that EPR power deposition can be greatly reduced using the FSE-PEDRI pulse sequence compared with the conventional gradient echo pulse sequence. High temporal resolution was achieved at ~4 s per image acquisition using the FSE-PEDRI sequence with a good image SNR in the range of 233-266 in the phantom study. The TEMPONE half-life measured in vivo was ~72 s. CONCLUSION Thus, the FSE-PEDRI pulse sequence enables fast in vivo functional imaging of free radical probes in small animals greatly reducing EPR irradiation time with decreased power deposition and provides increased temporal resolution.
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Affiliation(s)
- Ziqi Sun
- Davis Heart and Lung Research Institute and Division of Cardiovascular Medicine, Department of Internal Medicine, College of Medicine, The Ohio State University, Columbus, Ohio 43210, USA
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12
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Efimova OV, Caia GL, Sun Z, Petryakov S, Kesselring E, Samouilov A, Zweier JL. Standard-based method for proton-electron double resonance imaging of oxygen. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2011; 212:197-203. [PMID: 21807539 PMCID: PMC3235921 DOI: 10.1016/j.jmr.2011.06.030] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2011] [Revised: 06/24/2011] [Accepted: 06/28/2011] [Indexed: 05/31/2023]
Abstract
Proton-electron double resonance imaging (PEDRI) has been utilized for indirect determination of oxygen concentrations in aqueous samples and living systems. Due to the complexity of the problem, there are seven oxygen related parameters that need to be measured to determine the distribution of oxygen. We present an improved approach in which image intensities from only two PEDRI acquisitions with different EPR irradiation powers are required to determine the distribution of a paramagnetic probe and oxygen in an analyzed sample. This is achieved using three reference samples with known concentrations of a paramagnetic probe and oxygen placed inside the resonator together with the measurement sample. An EPR-off image, which has low signal intensity at low magnetic field (0.02 T) is not required for the calculations, significantly reducing the total time of the experiments and the noise while enhancing the accuracy of these oxygen measurements. The Finland trityl radical was used as the paramagnetic probe and oxygen concentrations could be accurately measured and imaged over the physiological range from 0 to 240 μM.
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Affiliation(s)
| | | | | | | | | | | | - Jay L. Zweier
- Corresponding author Dr. Jay L. Zweier, The Ohio State University, 473 W. 12 Avenue, Room 611C, Columbus, Ohio 43210, Phone 614-247-7788, Fax 614-247-7845,
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13
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Efimova OV, Sun Z, Petryakov S, Kesselring E, Caia GL, Johnson D, Zweier JL, Khramtsov VV, Samouilov A. Variable radio frequency proton-electron double-resonance imaging: application to pH mapping of aqueous samples. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2011; 209:227-232. [PMID: 21320790 PMCID: PMC3065501 DOI: 10.1016/j.jmr.2011.01.011] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2010] [Revised: 12/08/2010] [Accepted: 01/10/2011] [Indexed: 05/30/2023]
Abstract
Proton-electron double-resonance imaging (PEDRI) offers rapid image data collection and high resolution for spatial distribution of paramagnetic probes. Recently we developed the concept of variable field (VF) PEDRI which enables extracting a functional map from a limited number of images acquired at pre-selected EPR excitation fields using specific paramagnetic probes (Khramtsov et al., J. Magn. Reson. 202 (2010) 267-273). In this work, we propose and evaluate a new modality of PEDRI-based functional imaging with enhanced temporal resolution which we term variable radio frequency (VRF) PEDRI. The approach allows for functional mapping (e.g., pH mapping) using specifically designed paramagnetic probes with high quality spatial resolution and short acquisition times. This approach uses a stationary magnetic field but different EPR RFs. The ratio of Overhauser enhancements measured at each pixel at two different excitation frequencies corresponding to the resonances of protonated and deprotonated forms of a pH-sensitive nitroxide is converted to a pH map using a corresponding calibration curve. Elimination of field cycling decreased the acquisition time by exclusion periods of ramping and stabilization of the magnetic field. Improved magnetic field homogeneity and stability allowed for the fast MRI acquisition modalities such as fast spin echo. In total, about 30-fold decrease in EPR irradiation time was achieved for VRF PEDRI (2.4s) compared with VF PEDRI (70s). This is particularly important for in vivo applications enabling one to overcome the limiting stability of paramagnetic probes and sample overheating by reducing RF power deposition.
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Affiliation(s)
| | | | | | | | | | | | | | - Valery V. Khramtsov
- Corresponding authors: (Alexandre Samouilov); (Valery V. Khramtsov), Primary address for the correspondence during review process: Alexandre Samouilov, PhD, Davis Heart and Lung Research Institute, The Ohio State University, 420 West 12 Ave, Room 611B, Columbus, OH 43210
| | - Alexandre Samouilov
- Corresponding authors: (Alexandre Samouilov); (Valery V. Khramtsov), Primary address for the correspondence during review process: Alexandre Samouilov, PhD, Davis Heart and Lung Research Institute, The Ohio State University, 420 West 12 Ave, Room 611B, Columbus, OH 43210
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Shet K, Caia GL, Kesselring E, Samouilov A, Petryakov S, Lurie DJ, Zweier JL. A novel variable field system for field-cycled dynamic nuclear polarization spectroscopy. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2010; 205:202-208. [PMID: 20570197 PMCID: PMC4073606 DOI: 10.1016/j.jmr.2010.04.015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2010] [Revised: 04/26/2010] [Accepted: 04/26/2010] [Indexed: 05/29/2023]
Abstract
Dynamic nuclear polarization (DNP) is an NMR-based technique which enables detection and spectral characterization of endogenous and exogenous paramagnetic substances measured via transfer of polarization from the saturated unpaired electron spin system to the NMR active nuclei. A variable field system capable of performing DNP spectroscopy with NMR detection at any magnetic field in the range 0-0.38 T is described. The system is built around a clinical open-MRI system. To obtain EPR spectra via DNP, partial cancellation of the detection field B(0)(NMR) is required to alter the evolution field B(0)(EPR) at which the EPR excitation is achieved. The addition of resistive actively shielded field cancellation coils in the gap of the primary magnet provides this field offset in the range of 0-100 mT. A description of the primary magnet, cancellation coils, power supplies, interfacing hardware, RF electronics and console are included. Performance of the instrument has been evaluated by acquiring DNP spectra of phantoms with aqueous nitroxide solutions (TEMPOL) at three NMR detection fields of 97 G, 200 G and 587 G corresponding to 413 kHz, 851.6 kHz and 2.5 MHz respectively and fixed EPR evolution field of 100 G corresponding to an irradiation frequency of 282.3 MHz. This variable-field DNP system offers great flexibility for the performance of DNP spectroscopy with independent optimum choice of EPR excitation and NMR detection fields.
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Affiliation(s)
- Keerthi Shet
- Davis Heart and Lung Research Institute and the Division of Cardiovascular Medicine, The Ohio State University, College of Medicine, Columbus, Ohio 43210, USA
| | - George L. Caia
- Davis Heart and Lung Research Institute and the Division of Cardiovascular Medicine, The Ohio State University, College of Medicine, Columbus, Ohio 43210, USA
| | - Eric Kesselring
- Davis Heart and Lung Research Institute and the Division of Cardiovascular Medicine, The Ohio State University, College of Medicine, Columbus, Ohio 43210, USA
| | - Alexandre Samouilov
- Davis Heart and Lung Research Institute and the Division of Cardiovascular Medicine, The Ohio State University, College of Medicine, Columbus, Ohio 43210, USA
| | - Sergey Petryakov
- Davis Heart and Lung Research Institute and the Division of Cardiovascular Medicine, The Ohio State University, College of Medicine, Columbus, Ohio 43210, USA
| | - David J. Lurie
- Davis Heart and Lung Research Institute and the Division of Cardiovascular Medicine, The Ohio State University, College of Medicine, Columbus, Ohio 43210, USA
- Aberdeen Biomedical Imaging Centre, University of Aberdeen, Foresterhill, Aberdeen, Scotland, UK AB25 2ZD
| | - Jay L. Zweier
- Davis Heart and Lung Research Institute and the Division of Cardiovascular Medicine, The Ohio State University, College of Medicine, Columbus, Ohio 43210, USA
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Khramtsov VV, Caia GL, Shet K, Kesselring E, Petryakov S, Zweier JL, Samouilov A. Variable Field Proton-Electron Double-Resonance Imaging: Application to pH mapping of aqueous samples. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2010; 202:267-273. [PMID: 20007019 PMCID: PMC2818733 DOI: 10.1016/j.jmr.2009.11.017] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2009] [Revised: 08/27/2009] [Accepted: 11/20/2009] [Indexed: 05/28/2023]
Abstract
A new concept of Variable Field Proton-Electron Double-Resonance Imaging (VF PEDRI) is proposed. This allows for functional mapping using specifically designed paramagnetic probes (e.g. oxygen or pH mapping) with MRI high quality spatial resolution and short acquisition time. Studies performed at 200 G field MRI with phantoms show that a pH map of the sample can be extracted using only two PEDRI images acquired in 140 s at pre-selected EPR excitation fields providing pH resolution of 0.1 pH units and a spatial resolution of 1.25mm. Note that while concept of functional VF PEDRI was demonstrated using the pH probe, it can be applied for studies of other biologically relevant parameters of the medium such as redox state, concentrations of oxygen or glutathione using specifically designed EPR probes.
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Affiliation(s)
| | | | | | | | | | | | - Alexandre Samouilov
- Address for correspondence: Alexandre Samouilov, Davis Heart and Lung Research Institute, The Ohio State University, 420 West 12 Ave, Room 611B, Columbus, OH 43210.
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