1
|
Larson PEZ, Bernard JML, Bankson JA, Bøgh N, Bok RA, Chen AP, Cunningham CH, Gordon J, Hövener JB, Laustsen C, Mayer D, McLean MA, Schilling F, Slater J, Vanderheyden JL, von Morze C, Vigneron DB, Xu D. Current methods for hyperpolarized [1- 13C]pyruvate MRI human studies. Magn Reson Med 2024; 91:2204-2228. [PMID: 38441968 PMCID: PMC10997462 DOI: 10.1002/mrm.29875] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2023] [Revised: 08/12/2023] [Accepted: 09/06/2023] [Indexed: 03/07/2024]
Abstract
MRI with hyperpolarized (HP) 13C agents, also known as HP 13C MRI, can measure processes such as localized metabolism that is altered in numerous cancers, liver, heart, kidney diseases, and more. It has been translated into human studies during the past 10 years, with recent rapid growth in studies largely based on increasing availability of HP agent preparation methods suitable for use in humans. This paper aims to capture the current successful practices for HP MRI human studies with [1-13C]pyruvate-by far the most commonly used agent, which sits at a key metabolic junction in glycolysis. The paper is divided into four major topic areas: (1) HP 13C-pyruvate preparation; (2) MRI system setup and calibrations; (3) data acquisition and image reconstruction; and (4) data analysis and quantification. In each area, we identified the key components for a successful study, summarized both published studies and current practices, and discuss evidence gaps, strengths, and limitations. This paper is the output of the "HP 13C MRI Consensus Group" as well as the ISMRM Hyperpolarized Media MR and Hyperpolarized Methods and Equipment study groups. It further aims to provide a comprehensive reference for future consensus, building as the field continues to advance human studies with this metabolic imaging modality.
Collapse
Affiliation(s)
- Peder EZ Larson
- Department of Radiology and Biomedical Imaging, University
of California, San Francisco, CA 94143, USA
- UC Berkeley-UCSF Graduate Program in Bioengineering,
University of California, San Francisco and University of California, Berkeley, CA
94143, USA
| | - Jenna ML Bernard
- Department of Radiology and Biomedical Imaging, University
of California, San Francisco, CA 94143, USA
| | - James A Bankson
- Department of Imaging Physics, MD Anderson Medical Center,
Houston, TX, USA
| | - Nikolaj Bøgh
- The MR Research Center, Department of Clinical Medicine,
Aarhus University, Aarhus, Denmark
| | - Robert A Bok
- Department of Radiology and Biomedical Imaging, University
of California, San Francisco, CA 94143, USA
| | | | - Charles H Cunningham
- Physical Sciences, Sunnybrook Research Institute, Toronto,
Ontario, Canada
- Department of Medical Biophysics, University of Toronto,
Toronto, Ontario, Canada
| | - Jeremy Gordon
- Department of Radiology and Biomedical Imaging, University
of California, San Francisco, CA 94143, USA
| | - Jan-Bernd Hövener
- Section Biomedical Imaging, Molecular Imaging North
Competence Center (MOIN CC), Department of Radiology and Neuroradiology, University
Medical Center Schleswig-Holstein (UKSH), Kiel University, Am Botanischen Garten 14,
24118, Kiel, Germany
| | - Christoffer Laustsen
- The MR Research Center, Department of Clinical Medicine,
Aarhus University, Aarhus, Denmark
| | - Dirk Mayer
- Department of Diagnostic Radiology and Nuclear Medicine,
University of Maryland School of Medicine, Baltimore, MD, USA
- Greenebaum Cancer Center, University of Maryland School
of Medicine, Baltimore, MD, USA
| | - Mary A McLean
- Department of Radiology, University of Cambridge,
Cambridge, United Kingdom
- Cancer Research UK Cambridge Institute, University of
Cambridge, Li Ka Shing Center, Cambridge, United Kingdom
| | - Franz Schilling
- Department of Nuclear Medicine, School of Medicine,
Klinikum Rechts der Isar, Technical University of Munich, 81675 Munich,
Germany
| | - James Slater
- Department of Radiology and Biomedical Imaging, University
of California, San Francisco, CA 94143, USA
| | | | | | - Daniel B Vigneron
- Department of Radiology and Biomedical Imaging, University
of California, San Francisco, CA 94143, USA
- UC Berkeley-UCSF Graduate Program in Bioengineering,
University of California, San Francisco and University of California, Berkeley, CA
94143, USA
| | - Duan Xu
- Department of Radiology and Biomedical Imaging, University
of California, San Francisco, CA 94143, USA
- UC Berkeley-UCSF Graduate Program in Bioengineering,
University of California, San Francisco and University of California, Berkeley, CA
94143, USA
| | | |
Collapse
|
2
|
Frijia F, Flori A, Giovannetti G, Barison A, Menichetti L, Santarelli MF, Positano V. MRI Application and Challenges of Hyperpolarized Carbon-13 Pyruvate in Translational and Clinical Cardiovascular Studies: A Literature Review. Diagnostics (Basel) 2024; 14:1035. [PMID: 38786333 PMCID: PMC11120300 DOI: 10.3390/diagnostics14101035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2024] [Revised: 05/06/2024] [Accepted: 05/14/2024] [Indexed: 05/25/2024] Open
Abstract
Cardiovascular disease shows, or may even be caused by, changes in metabolism. Hyperpolarized magnetic resonance spectroscopy and imaging is a technique that could assess the role of different aspects of metabolism in heart disease, allowing real-time metabolic flux assessment in vivo. In this review, we introduce the main hyperpolarization techniques. Then, we summarize the use of dedicated radiofrequency 13C coils, and report a state of the art of 13C data acquisition. Finally, this review provides an overview of the pre-clinical and clinical studies on cardiac metabolism in the healthy and diseased heart. We furthermore show what advances have been made to translate this technique into the clinic in the near future and what technical challenges still remain, such as exploring other metabolic substrates.
Collapse
Affiliation(s)
- Francesca Frijia
- Bioengineering Unit, Fondazione Toscana G. Monasterio, 56124 Pisa, Italy; (A.F.); (V.P.)
| | - Alessandra Flori
- Bioengineering Unit, Fondazione Toscana G. Monasterio, 56124 Pisa, Italy; (A.F.); (V.P.)
| | - Giulio Giovannetti
- Institute of Clinical Physiology, National Research Council (CNR), 56124 Pisa, Italy; (G.G.); (L.M.); (M.F.S.)
| | - Andrea Barison
- Cardiology and Cardiovascular Medicine Unit, Fondazione Toscana G. Monasterio, 56124 Pisa, Italy;
| | - Luca Menichetti
- Institute of Clinical Physiology, National Research Council (CNR), 56124 Pisa, Italy; (G.G.); (L.M.); (M.F.S.)
| | - Maria Filomena Santarelli
- Institute of Clinical Physiology, National Research Council (CNR), 56124 Pisa, Italy; (G.G.); (L.M.); (M.F.S.)
| | - Vincenzo Positano
- Bioengineering Unit, Fondazione Toscana G. Monasterio, 56124 Pisa, Italy; (A.F.); (V.P.)
| |
Collapse
|
3
|
Larson PE, Bernard JM, Bankson JA, Bøgh N, Bok RA, Chen AP, Cunningham CH, Gordon J, Hövener JB, Laustsen C, Mayer D, McLean MA, Schilling F, Slater J, Vanderheyden JL, von Morze C, Vigneron DB, Xu D, Group THCMC. Current Methods for Hyperpolarized [1-13C]pyruvate MRI Human Studies. ARXIV 2023:arXiv:2309.04040v2. [PMID: 37731660 PMCID: PMC10508833] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 09/22/2023]
Abstract
MRI with hyperpolarized (HP) 13C agents, also known as HP 13C MRI, can measure processes such as localized metabolism that is altered in numerous cancers, liver, heart, kidney diseases, and more. It has been translated into human studies during the past 10 years, with recent rapid growth in studies largely based on increasing availability of hyperpolarized agent preparation methods suitable for use in humans. This paper aims to capture the current successful practices for HP MRI human studies with [1-13C]pyruvate - by far the most commonly used agent, which sits at a key metabolic junction in glycolysis. The paper is divided into four major topic areas: (1) HP 13C-pyruvate preparation, (2) MRI system setup and calibrations, (3) data acquisition and image reconstruction, and (4) data analysis and quantification. In each area, we identified the key components for a successful study, summarized both published studies and current practices, and discuss evidence gaps, strengths, and limitations. This paper is the output of the HP 13C MRI Consensus Group as well as the ISMRM Hyperpolarized Media MR and Hyperpolarized Methods & Equipment study groups. It further aims to provide a comprehensive reference for future consensus building as the field continues to advance human studies with this metabolic imaging modality.
Collapse
|
4
|
Traechtler J, Fuetterer M, Albannay MM, Hoh T, Kozerke S. Considerations for hyperpolarized 13 C MR at reduced field: Comparing 1.5T versus 3T. Magn Reson Med 2023; 89:1945-1960. [PMID: 36598063 DOI: 10.1002/mrm.29579] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Revised: 12/09/2022] [Accepted: 12/22/2022] [Indexed: 01/05/2023]
Abstract
PURPOSE In contrast to conventional MR, signal-to-noise ratio (SNR) is not linearly dependent on field strength in hyperpolarized MR, as polarization is generated outside the MR system. Moreover, field inhomogeneity-induced artifacts and other practical limitations associated with field strengths ≥ $$ \ge $$ 3T are alleviated at lower fields. The potential of hyperpolarized 13 $$ {}^{13} $$ C spectroscopy and imaging at 1.5T versus 3T is demonstrated in silico, in vitro, and in vivo for applications on clinical MR systems. THEORY AND METHODS Theoretical noise and SNR behavior at different field strengths are investigated based on simulations. A thorough field comparison between 1.5T and 3T is performed using thermal and hyperpolarized 13 $$ {}^{13} $$ C spectroscopy and imaging. Cardiac in vivo data is obtained in pigs using hyperpolarized [1- 13 $$ {}^{13} $$ C]pyruvate spectroscopy and imaging at 1.5T and 3T. RESULTS Based on theoretical considerations and simulations, the SNR of hyperpolarized MR at identical acquisition bandwidths is independent of the field strength for typical coil setups, while adaptively changing the acquisition bandwidth proportional to the static magnetic field allows for net SNR gains of up to 40% at 1.5T compared to 3T. In vitro 13 $$ {}^{13} $$ C data verified these considerations with less than 7% deviation. In vivo feasibility of hyperpolarized [1- 13 $$ {}^{13} $$ C]pyruvate dynamic metabolic spectroscopy and imaging at 1.5T is demonstrated in the pig heart with comparable SNR between 1.5T and 3T while B 0 $$ {}_0 $$ artifacts are noticeably reduced at 1.5T. CONCLUSION Hyperpolarized 13 $$ {}^{13} $$ C MR at lower field strengths is favorable in terms of SNR and off-resonance effects, which makes 1.5T a promising alternative to 3T, especially for clinical cardiac metabolic imaging.
Collapse
Affiliation(s)
- Julia Traechtler
- Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland
| | - Maximilian Fuetterer
- Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland
| | - Mohammed M Albannay
- Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland.,Laboratory of Physical Chemistry, ETH Zurich, Zurich, Switzerland
| | - Tobias Hoh
- Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland
| | - Sebastian Kozerke
- Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland
| |
Collapse
|
5
|
Sanchez‐Heredia JD, Olin RB, Grist JT, Wang W, Bøgh N, Zhurbenko V, Hansen ES, Schulte RF, Tyler D, Laustsen C, Ardenkjær‐Larsen JH. RF coil design for accurate parallel imaging on 13 C MRSI using 23 Na sensitivity profiles. Magn Reson Med 2022; 88:1391-1405. [PMID: 35635156 PMCID: PMC9328386 DOI: 10.1002/mrm.29259] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Revised: 02/14/2022] [Accepted: 03/14/2022] [Indexed: 11/22/2022]
Abstract
PURPOSE To develop a coil-based method to obtain accurate sensitivity profiles in 13 C MRI at 3T from the endogenous 23 Na. An eight-channel array is designed for 13 C MR acquisitions. As application examples, the array is used for two-fold accelerated acquisitions of both hyperpolarized 13 C metabolic imaging of pig kidneys and the human brain. METHODS A flexible coil array was tuned optimally for 13 C at 3T (32.1 MHz), with the coil coupling coefficients matched to be nearly identical at the resonance frequency of 23 Na (33.8 MHz). This is done by enforcing a high decoupling (obtained through highly mismatched preamplifiers) and adjusting the coupling frequency response. The SNR performance is compared to reference coils. RESULTS The measured sensitivity profiles on a phantom showed high spatial similarity for 13 C and 23 Na resonances, with average noise correlation of 9 and 11%, respectively. For acceleration factors 2, 3, and 4, the obtained maximum g-factors were 1.0, 1.1, and 2.6, respectively. The 23 Na profiles obtained in vivo could be used successfully to perform two-fold acceleration of hyperpolarized 13 C 3D acquisitions of both pig kidneys and a healthy human brain. CONCLUSION A receive array has been developed in such a way that the 13 C sensitivity profiles could be accurately obtained from measurements at the 23 Na frequency. This technique facilitates accelerated acquisitions for hyperpolarized 13 C imaging. The SNR performance obtained at the 13 C frequency, compares well to other state-of-the-art coils for the same purpose, showing slightly better superficial and central SNR.
Collapse
Affiliation(s)
| | - Rie B. Olin
- Department of Health TechnologyTechnical University of DenmarkKgs. LyngbyDenmark
| | - James T. Grist
- Department of Physiology, Anatomy and GeneticsUniversity of OxfordOxfordUK
- Oxford Centre for Clinical Magnetic Resonance ResearchUniversity of OxfordOxfordUK
- Department of RadiologyOxford University Hospitals TrustOxfordUK
- Institute of Cancer and Genomic SciencesUniversity of BirminghamBirminghamUK
| | - Wenjun Wang
- National Space InstituteTechnical University of DenmarkKgs. LyngbyDenmark
| | - Nikolaj Bøgh
- MR Research Centre, Department of Clinical MedicineAarhus UniversityAarhusDenmark
| | - Vitaliy Zhurbenko
- National Space InstituteTechnical University of DenmarkKgs. LyngbyDenmark
| | - Esben S. Hansen
- MR Research Centre, Department of Clinical MedicineAarhus UniversityAarhusDenmark
| | | | - Damian Tyler
- Department of Physiology, Anatomy and GeneticsUniversity of OxfordOxfordUK
- Oxford Centre for Clinical Magnetic Resonance ResearchUniversity of OxfordOxfordUK
| | - Christoffer Laustsen
- MR Research Centre, Department of Clinical MedicineAarhus UniversityAarhusDenmark
| | | |
Collapse
|
6
|
Brender JR, Kishimoto S, Eaton GR, Eaton SS, Saida Y, Mitchell J, Krishna MC. Trehalose as an alternative to glycerol as a glassing agent for in vivo DNP MRI. Magn Reson Med 2020; 85:42-48. [PMID: 32697878 DOI: 10.1002/mrm.28405] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Revised: 05/12/2020] [Accepted: 06/09/2020] [Indexed: 12/18/2022]
Abstract
PURPOSE In dynamic nuclear polarization (DNP), the solution needs to form a glass to attain significant levels of polarization in reasonable time periods. Molecules that do not form glasses by themselves are often mixed with glass forming excipients. Although glassing agents are often essential in DNP studies, they have the potential to perturb the metabolic measurements that are being studied. Glycerol, the glassing agent of choice for in vivo DNP studies, is effective in reducing ice crystal formation during freezing, but is rapidly metabolized, potentially altering the redox and adenosine triphosphate balance of the system. METHODS DNP buildup curves of 13 C urea and alanine with OX063 in the presence of trehalose, glycerol, and other polyol excipients were measured as a function of concentration. T1 and Tm relaxation times for OX063 in the presence of trehalose were measured by EPR. RESULTS Approximately 15-20 wt% trehalose gives a glass that polarizes samples more rapidly than the commonly used 60%-wt formulation of glycerol and yields similar polarization levels within clinically relevant timeframes. CONCLUSIONS Trehalose may be an attractive biologically inert alternative to glycerol for situations where there may be concerns about glycerol's glucogenic potential and possible alteration of the adenosine triphosphate/adenosine diphosphate and redox balance.
Collapse
Affiliation(s)
- Jeffrey R Brender
- Radiation Biology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Shun Kishimoto
- Radiation Biology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Gareth R Eaton
- Department of Chemistry & Biochemistry, University of Denver, Denver, CO, USA
| | - Sandra S Eaton
- Department of Chemistry & Biochemistry, University of Denver, Denver, CO, USA
| | - Yu Saida
- Radiation Biology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - James Mitchell
- Radiation Biology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Murali C Krishna
- Radiation Biology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| |
Collapse
|
7
|
A smart switching system to enable automatic tuning and detuning of metamaterial resonators in MRI scans. Sci Rep 2020; 10:10042. [PMID: 32572087 PMCID: PMC7308377 DOI: 10.1038/s41598-020-66884-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Accepted: 05/28/2020] [Indexed: 12/20/2022] Open
Abstract
We present a radio-frequency-activated switching system that can automatically detune a metamaterial resonator to enhance magnetic resonance imaging (MRI) performance. Local sensitivity-enhancing metamaterials typically consist of resonant components, which means that the transmitted radio frequency field is spatially inhomogeneous. The switching system shows for the first time that a metamaterial resonator can be detuned during transmission and tuned during reception using a digital circuit. This allows a resonating system to maintain homogeneous transmit field while maintaining an increased receive sensitivity. As a result, sensitivity can be enhanced without changing the system-provided specific absorption rate (SAR) models. The developed digital circuit consists of inductors sensitive to the transmit radio-frequency pulses, along with diodes acting as switches to control the resonance frequency of the resonator. We first test the automatic resonator detuning on-the-bench, and subsequently evaluate it in a 1.5 T MRI scanner using tissue-mimicking phantoms. The scan results demonstrate that the switching mechanism automatically detunes the resonator in transmit mode, while retaining its sensitivity-enhancing properties (tuned to the Larmor frequency) in receive mode. Since it does not require any connection to the MRI console, the switching system can have broad applications and could be adapted for use with other types of MRI scanners and field-enhancing resonators.
Collapse
|
8
|
Topping GJ, Hundshammer C, Nagel L, Grashei M, Aigner M, Skinner JG, Schulte RF, Schilling F. Acquisition strategies for spatially resolved magnetic resonance detection of hyperpolarized nuclei. MAGMA (NEW YORK, N.Y.) 2020; 33:221-256. [PMID: 31811491 PMCID: PMC7109201 DOI: 10.1007/s10334-019-00807-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Revised: 10/08/2019] [Accepted: 11/21/2019] [Indexed: 12/13/2022]
Abstract
Hyperpolarization is an emerging method in magnetic resonance imaging that allows nuclear spin polarization of gases or liquids to be temporarily enhanced by up to five or six orders of magnitude at clinically relevant field strengths and administered at high concentration to a subject at the time of measurement. This transient gain in signal has enabled the non-invasive detection and imaging of gas ventilation and diffusion in the lungs, perfusion in blood vessels and tissues, and metabolic conversion in cells, animals, and patients. The rapid development of this method is based on advances in polarizer technology, the availability of suitable probe isotopes and molecules, improved MRI hardware and pulse sequence development. Acquisition strategies for hyperpolarized nuclei are not yet standardized and are set up individually at most sites depending on the specific requirements of the probe, the object of interest, and the MRI hardware. This review provides a detailed introduction to spatially resolved detection of hyperpolarized nuclei and summarizes novel and previously established acquisition strategies for different key areas of application.
Collapse
Affiliation(s)
- Geoffrey J Topping
- Department of Nuclear Medicine, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
| | - Christian Hundshammer
- Department of Nuclear Medicine, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
| | - Luca Nagel
- Department of Nuclear Medicine, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
| | - Martin Grashei
- Department of Nuclear Medicine, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
| | - Maximilian Aigner
- Department of Nuclear Medicine, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
| | - Jason G Skinner
- Department of Nuclear Medicine, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
| | | | - Franz Schilling
- Department of Nuclear Medicine, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany.
| |
Collapse
|
9
|
Sánchez-Heredia JD, Baron R, Hansen ESS, Laustsen C, Zhurbenko V, Ardenkjaer-Larsen JH. Autonomous cryogenic RF receive coil for 13 C imaging of rodents at 3 T. Magn Reson Med 2019; 84:497-508. [PMID: 31782552 DOI: 10.1002/mrm.28113] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Revised: 10/15/2019] [Accepted: 11/14/2019] [Indexed: 12/26/2022]
Abstract
PURPOSE To develop an autonomous, in-bore, MR-compatible cryostat cooled with liquid nitrogen that provides full-day operation, and to demonstrate that the theoretical signal-to-noise benefit can be achieved for 13 C imaging at 3 T (32.13 MHz). METHODS The cryogenic setup uses a vacuum-insulated fiberglass cryostat, which indirectly cools a cold finger where the RF coil is attached. The cryostat was evacuated before use and had a reservoir of liquid nitrogen for full-day operation. A 30 × 40 mm2 copper coil was mounted inside the cryostat with a 3-mm distance to the sample. Two examples of in vivo experiments of rat brain metabolism after a hyperpolarized [1-13 C]pyruvate injection are reported. RESULTS A coil Q-factor ratio of Q88K /Q290K = 550/280 was obtained, and the theoretical SNR enhancement was verified with MR measurements. We achieved a coil temperature of 88 K and a preamplifier temperature of 77 K. A 2-fold overall SNR enhancement was achieved, compared with the best case at room temperature. The thermal performance of the coil was adequate for in vivo experiments, with an autonomy of 5 hours consuming 6 L of LN2 , extendable to over 12 hours by LN2 refilling. CONCLUSION Cryogenic surface coils can be highly beneficial for 13 C imaging, provided that the coil-to-sample distance remains short. An autonomous, in-bore cryostat was developed that achieved the theoretical improvement in SNR.
Collapse
Affiliation(s)
| | - Rafael Baron
- Department of Health Technology, Technical University of Denmark, Kongens Lyngby, Denmark
| | | | - Christoffer Laustsen
- MR Research Center, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Vitaliy Zhurbenko
- Department of Electrical Engineering, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Jan Henrik Ardenkjaer-Larsen
- Department of Health Technology, Technical University of Denmark, Kongens Lyngby, Denmark.,GE Healthcare, Brøndbyvester, Denmark
| |
Collapse
|
10
|
Johansen DH, Albannay MM, Petersen JR, Zhurbenko V, Ardenkjær-Larsen JH. PIN diode driver for NMR and MRI. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2019; 300:114-119. [PMID: 30738272 DOI: 10.1016/j.jmr.2019.01.017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Revised: 01/21/2019] [Accepted: 01/30/2019] [Indexed: 06/09/2023]
Abstract
Designing custom coils for magnetic resonance systems, such as nuclear magnetic resonance (NMR) spectrometers and magnetic resonance imaging (MRI) scanners, often entails using non-standard configurations of the transmit-receive (T/R) switch and Q-spoiling circuits. The built-in drivers of commercial NMR and MRI systems are, typically, only reconfigurable within a narrow application range (if at all). Thus, the built-in driver may not be able to properly control the custom T/R switches and Q-spoiling circuits when using custom built coils. We present a PIN diode driver which functions in both an MRI scanner and NMR spectrometer. The PIN diode driver is based on readily available discrete components and achieves switching times for the reverse and forward bias states (transmit on and off) of 2 μs and 0.4 μs respectively. Hence, this work enables a higher degree of customization of the RF switching circuits in an MR system and is potentially of interest for designers of custom coils for both NMR spectrometers and MRI scanners.
Collapse
Affiliation(s)
- D H Johansen
- Technical University of Denmark, Department of Electrical Engineering, Ørsteds Plads 349, Kgs. Lyngby, Denmark.
| | - M M Albannay
- Technical University of Denmark, Department of Electrical Engineering, Ørsteds Plads 349, Kgs. Lyngby, Denmark.
| | - J R Petersen
- Technical University of Denmark, Department of Electrical Engineering, Ørsteds Plads 349, Kgs. Lyngby, Denmark.
| | - V Zhurbenko
- Technical University of Denmark, Department of Electrical Engineering, Ørsteds Plads 349, Kgs. Lyngby, Denmark.
| | - J H Ardenkjær-Larsen
- Technical University of Denmark, Department of Electrical Engineering, Ørsteds Plads 349, Kgs. Lyngby, Denmark; General Electric, Brøndby, Denmark.
| |
Collapse
|
11
|
Sanchez-Heredia JD, Johansen DH, Hansen RB, Szocska Hansen ES, Laustsen C, Zhurbenko V, Ardenkjaer-Larsen JH. Improved Decoupling for Low Frequency MRI Arrays using Non-conventional Preamplifier Impedance. IEEE Trans Biomed Eng 2018; 66:1940-1948. [PMID: 30442598 DOI: 10.1109/tbme.2018.2881203] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
OBJECTIVE In this study, we describe a method to improve preamplifier decoupling in low frequency MRI receive coil arrays, where sample loading is low and coils exhibit a high Q-factor. METHODS The method relies on the higher decoupling obtained when coils are matched to an impedance higher than 50 Ω. Preamplifiers with inductive (and low resistive) input impedance, increase even further the effectiveness of the method. RESULTS We show that for poorly sample loaded coils, coupling to other elements in an array is a major source of SNR degradation due to a reduction of the coil Q-factor. An 8-channel 13C array at 32 MHz for imaging of the human head has been designed following this strategy. The improved decoupling even allowed constructing the array without overlapping of neighboring coils. Parallel imaging performance is also evaluated demonstrating a better spatial encoding of the array due to its non-overlapped geometry. CONCLUSION The proposed design strategy for coil arrays is beneficial for low frequency coils where the coil thermal noise is dominant. The method has been demonstrated on an 8-channel array for the human head for 13C MRI at 3 T (32 MHz), with almost 2-fold SNR enhancement when compared to a traditional array of similar size and number of elements. SIGNIFICANCE The proposed method is of relevance for low frequency arrays, where sample loading is low, and noise correlation is high due to insufficient coil decoupling.
Collapse
|
12
|
Timm KN, Miller JJ, Henry JA, Tyler DJ. Cardiac applications of hyperpolarised magnetic resonance. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2018; 106-107:66-87. [PMID: 31047602 DOI: 10.1016/j.pnmrs.2018.05.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Revised: 05/14/2018] [Accepted: 05/29/2018] [Indexed: 05/05/2023]
Abstract
Cardiovascular disease is the leading cause of death world-wide. It is increasingly recognised that cardiac pathologies show, or may even be caused by, changes in metabolism, leading to impaired cardiac energetics. The heart turns over 15 times its own weight in ATP every day and thus relies heavily on the availability of substrates and on efficient oxidation to generate this ATP. A number of old and emerging drugs that target different aspects of metabolism are showing promising results with regard to improved cardiac outcomes in patients. A non-invasive imaging technique that could assess the role of different aspects of metabolism in heart disease, as well as measure changes in cardiac energetics due to treatment, would be valuable in the routine clinical care of cardiac patients. Hyperpolarised magnetic resonance spectroscopy and imaging have revolutionised metabolic imaging, allowing real-time metabolic flux assessment in vivo for the first time. In this review we summarise metabolism in the healthy and diseased heart, give an introduction to the hyperpolarisation technique, 'dynamic nuclear polarisation' (DNP), and review the preclinical studies that have thus far explored healthy cardiac metabolism and different models of human heart disease. We furthermore show what advances have been made to translate this technique into the clinic, what technical challenges still remain and what unmet clinical needs and unexplored metabolic substrates still need to be assessed by researchers in this exciting and fast-moving field.
Collapse
Affiliation(s)
- Kerstin N Timm
- Department of Physiology, Anatomy and Genetics, University of Oxford, UK.
| | - Jack J Miller
- Department of Physiology, Anatomy and Genetics, University of Oxford, UK; Oxford Centre for Clinical Magnetic Resonance Research, John Radcliffe Hospital, Oxford, UK; Clarendon Laboratory, Department of Physics, University of Oxford, UK.
| | - John A Henry
- Department of Physiology, Anatomy and Genetics, University of Oxford, UK.
| | - Damian J Tyler
- Department of Physiology, Anatomy and Genetics, University of Oxford, UK; Oxford Centre for Clinical Magnetic Resonance Research, John Radcliffe Hospital, Oxford, UK.
| |
Collapse
|
13
|
Johansen DH, Sanchez-Heredia JD, Petersen JR, Johansen TK, Zhurbenko V, Ardenkjaer-Larsen JH. Cryogenic Preamplifiers for Magnetic Resonance Imaging. IEEE TRANSACTIONS ON BIOMEDICAL CIRCUITS AND SYSTEMS 2018; 12:202-210. [PMID: 29377808 DOI: 10.1109/tbcas.2017.2776256] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Pursuing the ultimate limit of detection in magnetic resonance imaging (MRI) requires cryogenics to decrease the thermal noise of the electronic circuits. As cryogenic coils for MRI are slowly emerging cryogenic preamplifiers are required to fully exploit their potential. A cryogenic preamplifier operated at 77 K is designed and implemented for C imaging at 3 T (32.13 MHz), using off-the-shelves components. The design is based on a high electron mobility transistor (ATF54143) in a common source configuration. Required auxiliary circuitry for optimal cryogenic preamplifier performance is also presented consisting of a voltage regulator (noise free supply voltage and optimal power consumption), switch, and trigger (for active detuning during transmission to protect the preamplifier). A gain of 18 dB with a noise temperature of 13.7 K is achieved. Performing imaging experiments in a 3 T scanner showed an 8% increased signal-to-noise ratio from 365 to 399 when lowering the temperature of the preamplifier from 296 to 77 K while keeping the coil at room temperature. This paper thus enables the merger of cryogenic coils and preamplifiers in the hopes of reaching the ultimate limit of detection for MRI.
Collapse
|