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Ebersberger L, Kratzer FJ, Franke VL, Nagel AM, Niesporek SC, Korzowski A, Ladd ME, Schlemmer HP, Paech D, Platt T. First implementation of dynamic oxygen-17 ( 17O) magnetic resonance imaging at 7 Tesla during neuronal stimulation in the human brain. MAGMA (NEW YORK, N.Y.) 2024; 37:27-38. [PMID: 37737942 PMCID: PMC10876824 DOI: 10.1007/s10334-023-01119-6] [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: 03/28/2023] [Revised: 08/27/2023] [Accepted: 08/31/2023] [Indexed: 09/23/2023]
Abstract
OBJECTIVE First implementation of dynamic oxygen-17 (17O) MRI at 7 Tesla (T) during neuronal stimulation in the human brain. METHODS Five healthy volunteers underwent a three-phase 17O gas (17O2) inhalation experiment. Combined right-side visual stimulus and right-hand finger tapping were used to achieve neuronal stimulation in the left cerebral hemisphere. Data analysis included the evaluation of the relative partial volume (PV)-corrected time evolution of absolute 17O water (H217O) concentration and of the relative signal evolution without PV correction. Statistical analysis was performed using a one-tailed paired t test. Blood oxygen level-dependent (BOLD) experiments were performed to validate the stimulation paradigm. RESULTS The BOLD maps showed significant activity in the stimulated left visual and sensorimotor cortex compared to the non-stimulated right side. PV correction of 17O MR data resulted in high signal fluctuations with a noise level of 10% due to small regions of interest (ROI), impeding further quantitative analysis. Statistical evaluation of the relative H217O signal with PV correction (p = 0.168) and without (p = 0.382) did not show significant difference between the stimulated left and non-stimulated right sensorimotor ROI. DISCUSSION The change of cerebral oxygen metabolism induced by sensorimotor and visual stimulation is not large enough to be reliably detected with the current setup and methodology of dynamic 17O MRI at 7 T.
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Affiliation(s)
- Louise Ebersberger
- German Cancer Research Center (DKFZ) Heidelberg, Division of Radiology, Heidelberg, Germany
- Faculty of Medicine, Ruprecht-Karls University Heidelberg, Heidelberg, Germany
- Department of Pediatrics, Bern University Hospital, Bern, Switzerland
| | - Fabian J Kratzer
- German Cancer Research Center (DKFZ) Heidelberg, Division of Medical Physics in Radiology, Heidelberg, Germany
| | - Vanessa L Franke
- German Cancer Research Center (DKFZ) Heidelberg, Division of Medical Physics in Radiology, Heidelberg, Germany
- Faculty of Physics and Astronomy, Ruprecht-Karls University Heidelberg, Heidelberg, Germany
| | - Armin M Nagel
- German Cancer Research Center (DKFZ) Heidelberg, Division of Medical Physics in Radiology, Heidelberg, Germany
- Institute of Radiology, Friedrich-Alexander University Hospital Erlangen-Nürnberg (FAU), University Hospital Erlangen, Erlangen, Germany
| | - Sebastian C Niesporek
- German Cancer Research Center (DKFZ) Heidelberg, Division of Medical Physics in Radiology, Heidelberg, Germany
| | - Andreas Korzowski
- German Cancer Research Center (DKFZ) Heidelberg, Division of Medical Physics in Radiology, Heidelberg, Germany
| | - Mark E Ladd
- Faculty of Medicine, Ruprecht-Karls University Heidelberg, Heidelberg, Germany
- German Cancer Research Center (DKFZ) Heidelberg, Division of Medical Physics in Radiology, Heidelberg, Germany
- Faculty of Physics and Astronomy, Ruprecht-Karls University Heidelberg, Heidelberg, Germany
| | - Heinz-Peter Schlemmer
- German Cancer Research Center (DKFZ) Heidelberg, Division of Radiology, Heidelberg, Germany
| | - Daniel Paech
- German Cancer Research Center (DKFZ) Heidelberg, Division of Radiology, Heidelberg, Germany
- Department of Neuroradiology, University Hospital Bonn, Bonn, Germany
| | - Tanja Platt
- German Cancer Research Center (DKFZ) Heidelberg, Division of Medical Physics in Radiology, Heidelberg, Germany.
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Choi CH, Felder J, Lerche C, Shah NJ. MRI Coil Development Strategies for Hybrid MR-PET Systems: A Review. IEEE Rev Biomed Eng 2024; 17:342-350. [PMID: 37015609 DOI: 10.1109/rbme.2022.3227337] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Simultaneously operating MR-PET systems have the potential to provide synergetic multi-parametric information, and, as such, interest surrounding their use and development is increasing. However, despite the potential advantages offered by fully combined MR-PET systems, implementing this hybrid integration is technically laborious, and any factors degrading the quality of either modality must be circumvented to ensure optimal performance. In order to attain the best possible quality from both systems, most full MR-PET integrations tend to place the shielded PET system inside the MRI system, close to the target volume of the subject. The radiofrequency (RF) coil used in MRI systems is a key factor in determining the quality of the MR images, and, in simultaneous acquisition, it is generally positioned inside the PET system and PET imaging region, potentially resulting in attenuation and artefacts in the PET images. Therefore, when designing hybrid MR-PET systems, it is imperative that consideration be given to the RF coils inside the PET system. In this review, we present current state-of-the-art RF coil designs used for hybrid MR-PET experiments and discuss various design strategies for constructing PET transparent RF coils.
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Lopez Kolkovsky AL, Carlier PG, Marty B, Meyerspeer M. Interleaved and simultaneous multi-nuclear magnetic resonance in vivo. Review of principles, applications and potential. NMR IN BIOMEDICINE 2022; 35:e4735. [PMID: 35352440 PMCID: PMC9542607 DOI: 10.1002/nbm.4735] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Revised: 03/03/2022] [Accepted: 03/28/2022] [Indexed: 06/14/2023]
Abstract
Magnetic resonance signals from different nuclei can be excited or received at the same time,rendering simultaneous or rapidly interleaved multi-nuclear acquisitions feasible. The advan-tages are a reduction of total scan time compared to sequential multi-nuclear acquisitions or that additional information from heteronuclear data is obtained at thesame time and anatomical position. Information content can be qualitatively increased by delivering a more comprehensive MR-based picture of a transient state (such as an exercise bout). Also, combiningnon-proton MR acquisitions with 1 Hinformation (e.g., dynamic shim updates and motion correction) can be used to improve data quality during long scans and benefits image coregistration. This work reviews the literature on interleaved and simultaneous multi-nuclear MRI and MRS in vivo. Prominent use cases for this methodology in clinical and research applications are brain and muscle, but studies have also been carried out in other targets, including the lung, knee, breast and heart. Simultaneous multi-nuclear measurements in the liver and kidney have also been performed, but exclusively in rodents. In this review, a consistent nomenclature is proposed, to help clarify the terminology used for this principle throughout the literature on in-vivo MR. An overview covers the basic principles, the technical requirements on the MR scanner and the implementations realised either by MR system vendors or research groups, from the early days until today. Considerations regarding the multi-tuned RF coils required and heteronuclear polarisation interactions are briefly discussed, and fields for future in-vivo applications for interleaved multi-nuclear MR pulse sequences are identified.
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Affiliation(s)
- Alfredo L. Lopez Kolkovsky
- NMR Laboratory, Neuromuscular Investigation CenterInstitute of MyologyParisFrance
- NMR laboratoryCEA, DRF, IBFJParisFrance
| | - Pierre G. Carlier
- NMR Laboratory, Neuromuscular Investigation CenterInstitute of MyologyParisFrance
- NMR laboratoryCEA, DRF, IBFJParisFrance
| | - Benjamin Marty
- NMR Laboratory, Neuromuscular Investigation CenterInstitute of MyologyParisFrance
- NMR laboratoryCEA, DRF, IBFJParisFrance
| | - Martin Meyerspeer
- High‐Field MR Center, Center for Medical Physics and Biomedical EngineeringMedical University of ViennaViennaAustria
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Choi CH, Hong SM, Felder J, Tellmann L, Scheins J, Kops ER, Lerche C, Shah NJ. A Novel J-Shape Antenna Array for Simultaneous MR-PET or MR-SPECT Imaging. IEEE TRANSACTIONS ON MEDICAL IMAGING 2022; 41:1104-1113. [PMID: 34860648 DOI: 10.1109/tmi.2021.3132576] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Simultaneous MR-PET/-SPECT is an emerging technology that capitalises on the invaluable advantages of both modalities, allowing access to numerous sensitive tracers and superior soft-tissue contrast alongside versatile functional imaging capabilities. However, to optimise these capabilities, concurrent acquisitions require the MRI antenna located inside the PET/SPECT field-of-view to be operated without compromising any aspects of system performance or image quality compared to the stand-alone instrumentation. Here, we report a novel gamma-radiation-transparent antenna concept. The end-fed J-shape antenna is particularly adept for hybrid ultra-high field MR-PET/-SPECT applications as it enables all highly attenuating materials to be placed outside the imaging field-of-view. Furthermore, this unique configuration also provides advantages in stand-alone MR applications by reducing the amount of coupling between the cables and the antenna elements, and by lowering the potential specific absorption rate burden. The use of this new design was experimentally verified according to the important features for both ultra-high field MRI and the 511 keV transmission scan. The reconstructed attenuation maps evidently showed much lower attenuation ( ∼ 15 %) for the proposed array when compared to the conventional dipole antenna array since there were no high-density components. In MR, it was observed that the signal-to-noise ratio from the whole volume obtained using the proposed array was comparable to that acquired by the conventional array which was also in agreement with the simulation results. The unique feature, J-shape array, would enable simultaneous MR-PET/-SPECT experiments to be conducted without unduly compromising any aspects of system performance and image quality compared to the stand-alone instrumentation.
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Seo JH, Chung JY. A Preliminary Study for Reference RF Coil at 11.7 T MRI: Based on Electromagnetic Field Simulation of Hybrid-BC RF Coil According to Diameter and Length at 3.0, 7.0 and 11.7 T. SENSORS 2022; 22:s22041512. [PMID: 35214409 PMCID: PMC8875900 DOI: 10.3390/s22041512] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Revised: 02/13/2022] [Accepted: 02/14/2022] [Indexed: 02/05/2023]
Abstract
Magnetic resonance imaging (MRI) systems must undergo quantitative evaluation through daily and periodic performance assessments. In general, the reference or standard radiofrequency (RF) coils for these performance assessments of 1.5 to 7.0 T MRI systems have been low-pass-type birdcage (LP-BC) RF coils. However, LP-BC RF coils are inappropriate for use as reference RF coils because of their relatively lower magnetic field (B1-field) sensitivity than other types of BC RF coils, especially in ultrahigh-field (UHF) MRI systems above 3.0 T. Herein, we propose a hybrid-type BC (Hybrid-BC) RF coil as a reference RF coil with improved B1-field sensitivity in UHF MRI system and applied it to an 11.7 T MRI system. An electromagnetic field (EM-field) analysis on the Hybrid-BC RF coil was performed to provide the proper dimensions for its use as a reference RF coil. Commercial finite difference time-domain program was used in EM-field simulation, and home-made analysis programs were used in analysis. The optimal specifications of the proposed Hybrid-BC RF coils for them to qualify as reference RF coils are proposed based on their B1+-field sensitivity under unnormalized conditions, as well as by considering their B1+-field uniformity and RF safety under normalized conditions.
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Affiliation(s)
- Jeung-Hoon Seo
- Neuroscience Research Institute, Gachon University, Incheon 21988, Korea;
| | - Jun-Young Chung
- Department of Neuroscience, College of Medicine, Gachon University, Incheon 21565, Korea
- Correspondence: ; Tel.: +82-32-822-5361; Fax: +82-32-822-8251
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Choi CH, Hong SM, Felder J, Shah NJ. The state-of-the-art and emerging design approaches of double-tuned RF coils for X-nuclei, brain MR imaging and spectroscopy: A review. Magn Reson Imaging 2020; 72:103-116. [DOI: 10.1016/j.mri.2020.07.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 06/16/2020] [Accepted: 07/01/2020] [Indexed: 12/18/2022]
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Dehkharghani S, Qiu D. MR Thermometry in Cerebrovascular Disease: Physiologic Basis, Hemodynamic Dependence, and a New Frontier in Stroke Imaging. AJNR Am J Neuroradiol 2020; 41:555-565. [PMID: 32139425 DOI: 10.3174/ajnr.a6455] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Accepted: 01/02/2020] [Indexed: 01/20/2023]
Abstract
The remarkable temperature sensitivity of the brain is widely recognized and has been studied for its role in the potentiation of ischemic and other neurologic injuries. Pyrexia frequently complicates large-vessel acute ischemic stroke and develops commonly in critically ill neurologic patients; the profound sensitivity of the brain even to minor intraischemic temperature changes, together with the discovery of brain-to-systemic as well as intracerebral temperature gradients, has thus compelled the exploration of cerebral thermoregulation and uncovered its immutable dependence on cerebral blood flow. A lack of pragmatic and noninvasive tools for spatially and temporally resolved brain thermometry has historically restricted empiric study of cerebral temperature homeostasis; however, MR thermometry (MRT) leveraging temperature-sensitive nuclear magnetic resonance phenomena is well-suited to bridging this long-standing gap. This review aims to introduce the reader to the following: 1) fundamental aspects of cerebral thermoregulation, 2) the physical basis of noninvasive MRT, and 3) the physiologic interdependence of cerebral temperature, perfusion, metabolism, and viability.
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Affiliation(s)
- S Dehkharghani
- From the Department of Radiology (S.D.), New York University Langone Health, New York, New York
| | - D Qiu
- Department of Radiology (D.Q.), Emory University Hospital, Atlanta, Georgia
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