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Chen B, Dammann P, Jabbarli R, Sure U, Quick HH, Kraff O, Wrede KH. Safety and function of programmable ventriculo-peritoneal shunt valves: An in vitro 7 Tesla magnetic resonance imaging study. PLoS One 2023; 18:e0292666. [PMID: 37819939 PMCID: PMC10566673 DOI: 10.1371/journal.pone.0292666] [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] [Received: 03/15/2023] [Accepted: 09/26/2023] [Indexed: 10/13/2023] Open
Abstract
OBJECTIVE The quantity of ultra-high field MRI neuroimaging studies has rapidly increased. This study tests function, safety, and image artifacts of two frequently implanted programmable ventriculo-peritoneal (VP) shunt valves in a 7T MRI system. METHODS All tests were performed using a whole-body 7T MRI system. Three proGAV 2.0 and 3 CODMAN CERTAS® Plus programmable VP-shunt valves were tested in three steps. 1) Deflection angle tests close to the bore opening at the location of a static magnetic field gradient of 3-5 T/m. 2) Valves were fixed on a spherical phantom in 3 positions (a. lateral, b. cranial, c. cranial with 22.5° tilt anteriorly) and assessed for keeping the programmed pressure setting and reprogrammability. 3) Valves were fixed on the phantom and positioned lateral in a radiofrequency head coil. MRI scans were performed for both models, including MPRAGE, GRE and SE sequences. RESULTS Deflection angles were moderate (13°, 14°, 13°) for the proGAV valves and close to critical (43°, 43°, 41°) for the CODMAN valves at the test location. Taking a scaling factor of 2-3 for the maximum spatial magnetic field gradient accessible to a patient within the magnet bore into account renders both valves MR unsafe regarding ferromagnetic attraction. The proGAV valves kept the pressure settings in all positions and were reprogrammable in positions a. and b. In position c., reprogrammability was lost. The CODMAN valves changed their pressure setting and reprogrammability was lost in all positions. MR image signal homogeneity was unaltered in the phantom center, artifacts limit the assessability of structures in close vicinity to the valves. CONCLUSION Both tested programmable VP-shunt valves are MR unsafe for 7T systems. Novel programming mechanisms using permanent magnets with sufficient magnetic coercivity or magnet-free mechanisms may allow the development of programmable VP-shunt valves that are conditional for 7T MR systems.
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Affiliation(s)
- Bixia Chen
- Erwin L. Hahn Institute for Magnetic Resonance Imaging, University Duisburg-Essen, Essen, North Rhine Westphalia, Germany
- Department of Neurosurgery, University Hospital Essen, University Duisburg-Essen, Essen, North Rhine Westphalia, Germany
| | - Philipp Dammann
- Erwin L. Hahn Institute for Magnetic Resonance Imaging, University Duisburg-Essen, Essen, North Rhine Westphalia, Germany
- Department of Neurosurgery, University Hospital Essen, University Duisburg-Essen, Essen, North Rhine Westphalia, Germany
| | - Ramazan Jabbarli
- Department of Neurosurgery, University Hospital Essen, University Duisburg-Essen, Essen, North Rhine Westphalia, Germany
| | - Ulrich Sure
- Department of Neurosurgery, University Hospital Essen, University Duisburg-Essen, Essen, North Rhine Westphalia, Germany
| | - Harald H. Quick
- Erwin L. Hahn Institute for Magnetic Resonance Imaging, University Duisburg-Essen, Essen, North Rhine Westphalia, Germany
- High-Field and Hybrid MR Imaging, University Hospital Essen, University Duisburg-Essen, Essen, North Rhine Westphalia, Germany
| | - Oliver Kraff
- Erwin L. Hahn Institute for Magnetic Resonance Imaging, University Duisburg-Essen, Essen, North Rhine Westphalia, Germany
| | - Karsten H. Wrede
- Erwin L. Hahn Institute for Magnetic Resonance Imaging, University Duisburg-Essen, Essen, North Rhine Westphalia, Germany
- Department of Neurosurgery, University Hospital Essen, University Duisburg-Essen, Essen, North Rhine Westphalia, Germany
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2
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Velicki K, Mazziotti J, Pihl C, Yang S. Flexible Titanium Intramedullary Nail Displacement After Magnetic Resonance Imaging. J Am Acad Orthop Surg Glob Res Rev 2023; 7:01979360-202309000-00013. [PMID: 37747696 PMCID: PMC10519503 DOI: 10.5435/jaaosglobal-d-23-00004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Accepted: 07/17/2023] [Indexed: 09/26/2023]
Abstract
CASE A previously healthy 7-year-old boy presented with midshaft radius and ulna malunion after 8 weeks of nonsurgical treatment. He underwent open reduction and internal fixation of both bones with titanium alloy nails and was placed in a long arm cast. Four weeks after surgery, the patient underwent sedated brain MRI and woke up from anesthesia with elbow pain. On cast removal, the ulnar flexible nail was noted to have displaced proximally by 1.5 cm. CONCLUSION Despite meeting American Society for Testing and Materials standards, untethered titanium orthopaedic implants are at risk of clinically significant displacement in the early postoperative period.
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Affiliation(s)
- Katherine Velicki
- From the Department of Orthopaedic Surgery, Oregon Health & Science University, Portland, OR
| | - Julianna Mazziotti
- From the Department of Orthopaedic Surgery, Oregon Health & Science University, Portland, OR
| | - Connor Pihl
- From the Department of Orthopaedic Surgery, Oregon Health & Science University, Portland, OR
| | - Scott Yang
- From the Department of Orthopaedic Surgery, Oregon Health & Science University, Portland, OR
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3
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Shaffer A, Nigh N, Weisbaum D, Anderson A, Wszalek T, Sutton BP, Webb A, Damon B, Moussa I, Arnold PM. Cardiothoracic and Vascular Surgery Implant Compatibility With Ultrahigh Field Magnetic Resonance Imaging (4.7 Tesla and 7 Tesla). Am J Cardiol 2023; 201:239-246. [PMID: 37392607 DOI: 10.1016/j.amjcard.2023.05.062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Revised: 05/23/2023] [Accepted: 05/31/2023] [Indexed: 07/03/2023]
Abstract
The use of 7 Tesla (T) magnetic resonance imaging (MRI) is expanding across medical specialties, particularly, clinical neurosciences and orthopedics. Investigational 7 T MRI has also been performed in cardiology. A limiting factor for expansion of the role of 7 T, irrespective of the body part being imaged, is the sparse testing of biomedical implant compatibility at field strengths >3 T. Implant compatibility can be tested following the American Society for Testing and Materials International guidelines. To assess the current state of cardiovascular implant safety at field strengths >3 T, a systematic search was performed using PubMed, Web of Science, and citation matching. Studies written in English that included at least 1 cardiovascular-related implant and at least 1 safety outcome (deflection angle, torque, or temperature change) were included. Data were extracted for the implant studied, implant composition, deflection angle, torque, and temperature change, and the American Society for Testing and Materials International standards were followed. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses reporting guidelines for scoping reviews were followed. A total of 9 studies were included. A total of 34 cardiovascular-related implants tested ex vivo at 7 T and 91 implants tested ex vivo at 4.7 T were included. The implants included vascular grafts and conduits, vascular access ports, peripheral and coronary stents, caval filters, and artificial valves. A total of 2 grafts, 1 vascular access port, 2 vena cava filters, and 5 stents were identified as incompatible with the 7 T MRI. All incompatible stents were 40 mm in length. Based on the safety outcomes reported, we identify several implants that may be compatible with >3 T MRI. This scoping review seeks to concisely summarize all the cardiovascular-related implants tested for ultrahigh field MRI compatibility to date.
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Affiliation(s)
- Annabelle Shaffer
- Carle Illinois College of Medicine, University of Illinois Urbana Champaign, Urbana, Illinois
| | - Noah Nigh
- Carle Illinois College of Medicine, University of Illinois Urbana Champaign, Urbana, Illinois
| | - David Weisbaum
- Department of Neurosurgery, Carle Foundation Hospital, Urbana, Illinois
| | - Aaron Anderson
- Carle Illinois Advanced Imaging Center, Carle Foundation Hospital, Urbana, Illinois; Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Tracey Wszalek
- Carle Illinois Advanced Imaging Center, Carle Foundation Hospital, Urbana, Illinois; Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Bradley P Sutton
- Carle Illinois College of Medicine, University of Illinois Urbana Champaign, Urbana, Illinois; Carle Illinois Advanced Imaging Center, Carle Foundation Hospital, Urbana, Illinois; Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Andrew Webb
- Carle Illinois Advanced Imaging Center, Carle Foundation Hospital, Urbana, Illinois; Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands; Leiden University Medical Center, Leiden, The Netherlands
| | - Bruce Damon
- Carle Illinois Advanced Imaging Center, Carle Foundation Hospital, Urbana, Illinois; Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Issam Moussa
- Carle Illinois College of Medicine, University of Illinois Urbana Champaign, Urbana, Illinois; Heart and Vascular Institute, Carle Foundation Hospital, Urbana, Illinois
| | - Paul M Arnold
- Carle Illinois College of Medicine, University of Illinois Urbana Champaign, Urbana, Illinois; Department of Neurosurgery, Carle Foundation Hospital, Urbana, Illinois.
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4
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Shaffer A, Weisbaum D, Naik A, Anderson A, Wszalek T, Cohen M, Sutton B, Webb A, Damon B, Arnold PM. Neurosurgical Implant Safety in 7 T MRI: A Scoping Review. J Magn Reson Imaging 2023; 57:661-669. [PMID: 36173367 DOI: 10.1002/jmri.28449] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Revised: 09/13/2022] [Accepted: 09/15/2022] [Indexed: 11/11/2022] Open
Abstract
The use of 7 Tesla (T) magnetic resonance imaging (MRI) is expanding across neurosurgical and neurologic specialties. However, few neurosurgical-related implants have been tested for safety at 7 T, limiting its use in patients with cranial fixation, shunt placements, and other implants. Implant safety can be determined via the American Society for Testing Materials International (ASTM) guidelines. To assess the current state of neurosurgical implant safety at 7 T, a systematic search was performed using PubMed, MEDLINE, Web of Knowledge, and citation matching. Studies written in English that included at least one neurosurgical implant and at least one safety outcome were included. Data were extracted for implant studied, implant composition, deflection angle, torque, temperature change, and ASTM guidelines followed. PRISMA reporting guidelines for scoping reviews were followed. Overall, 18 studies consisting of 45 unique implants were included. Implants included cranial fixation devices, aneurysm clips, spinal rods, pedicle screws, ventriculoperitoneal (VP) shunts, deep brain stimulation devices, and electroencephalogram (EEG) caps and electrodes. Cranial fixation devices, deep brain stimulation devices, spinal rods, and pedicle screws are likely 7 T MRI compatible based on outcomes reported. Aneurysm clips and EEG devices had variable safety outcomes. The VP shunts studied lost functionality after 7 T MRI exposure. We identified several implants that are likely compatible with 7 T MRI. Given the growth in 7 T imaging and expansion of the technology, neurosurgical implants should be constructed with the aforementioned considerations. Caution must be taken with all implants, especially aneurysm clips, programmable VP shunts, and EEG recording devices. It is also noteworthy that several implant testing reports did not report following ASTM standards. This scoping review seeks to concisely summarize all neurosurgical-related implants that have been tested for safety in 7 T MRI. EVIDENCE LEVEL: 2 TECHNICAL EFFICACY: Stage 2.
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Affiliation(s)
- Annabelle Shaffer
- Carle Illinois College of Medicine, University of Illinois Urbana Champaign, Urbana, Illinois, USA
| | - David Weisbaum
- Department of Neurosurgery, Carle Foundation Hospital, Urbana, Illinois, USA
| | - Anant Naik
- Carle Illinois College of Medicine, University of Illinois Urbana Champaign, Urbana, Illinois, USA
| | - Aaron Anderson
- Carle Illinois Advanced Imaging Center, Urbana, Illinois, USA.,Beckman Institute for Advanced Science & Technology, University of Illinois Urbana Champaign, Urbana, Illinois, USA
| | - Tracey Wszalek
- Carle Illinois Advanced Imaging Center, Urbana, Illinois, USA.,Beckman Institute for Advanced Science & Technology, University of Illinois Urbana Champaign, Urbana, Illinois, USA
| | - Mark Cohen
- Carle Illinois College of Medicine, University of Illinois Urbana Champaign, Urbana, Illinois, USA
| | - Brad Sutton
- Carle Illinois Advanced Imaging Center, Urbana, Illinois, USA.,Beckman Institute for Advanced Science & Technology, University of Illinois Urbana Champaign, Urbana, Illinois, USA
| | - Andrew Webb
- Carle Illinois Advanced Imaging Center, Urbana, Illinois, USA.,Beckman Institute for Advanced Science & Technology, University of Illinois Urbana Champaign, Urbana, Illinois, USA.,Leiden University Medical Center, Leiden, Netherlands
| | - Bruce Damon
- Carle Illinois Advanced Imaging Center, Urbana, Illinois, USA.,Beckman Institute for Advanced Science & Technology, University of Illinois Urbana Champaign, Urbana, Illinois, USA
| | - Paul M Arnold
- Carle Illinois College of Medicine, University of Illinois Urbana Champaign, Urbana, Illinois, USA.,Department of Neurosurgery, Carle Foundation Hospital, Urbana, Illinois, USA
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5
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Burke CJ, Khodarahmi I, Fritz J. Postoperative MR Imaging of Joints. Magn Reson Imaging Clin N Am 2022; 30:583-600. [DOI: 10.1016/j.mric.2022.03.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
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6
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Tsutsui S, Matsuda T, Takeda K, Sasaki M, Kubo Y, Setta K, Fujiwara S, Chida K, Ogasawara K. Assessment of Heating on Titanium Alloy Cerebral Aneurysm Clips during 7T MRI. AJNR Am J Neuroradiol 2022; 43:972-977. [PMID: 35738672 DOI: 10.3174/ajnr.a7561] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Accepted: 05/06/2022] [Indexed: 12/15/2022]
Abstract
BACKGROUND AND PURPOSE Patients with cerebral aneurysms often undergo MR imaging after microsurgical clipping. Ultra-high-field MR imaging at 7T may provide high diagnostic capability in such clinical situations. However, titanium alloy clips have safety issues such as adverse interactions with static magnetic fields and radiofrequency-induced heating during 7T MR imaging. The purpose of this study was to quantitatively assess temperature increases on various types of titanium alloy aneurysm clips during 7T MR imaging. MATERIALS AND METHODS Five types of titanium alloy aneurysm clips were tested, including combinations of short, long, straight, angled, and fenestrated types. Each clip was set in a phantom filled with gelled saline mixed with polyacrylic acid and underwent 7T MR imaging with 3D T1WI with a spoiled gradient recalled acquisition in the steady-state technique. Temperature was chronologically measured at the tips of the clip blade and head, angled part of the clip, and 5 mm from the tip of the clip head using MR imaging-compatible fiber-optic thermometers. RESULTS Temperature increases at all locations for right-angled and short straight clips were <1°C. Temperature increases at the angled part for the 45° angled clip and the tip of the clip head for the straight fenestrated clip were >1°C. Temperature increases at all locations for the long straight clip were >2°C. CONCLUSIONS Temperature increases on the right-angled and short straight clips remained below the regulatory limit during 7T MR imaging, but temperature increases on the 45° angled, straight fenestrated, and long straight clips exceeded this limit.
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Affiliation(s)
- S Tsutsui
- From the Department of Neurosurgery (S.T., Y.K., K.S., S.F., K.C., K.O.)
| | - T Matsuda
- Division of Ultrahigh Field MRI (T.M., K.T., M.S.), Institute for Biomedical Sciences, Iwate Medical University School of Medicine, Morioka, Japan
| | - K Takeda
- Division of Ultrahigh Field MRI (T.M., K.T., M.S.), Institute for Biomedical Sciences, Iwate Medical University School of Medicine, Morioka, Japan
| | - M Sasaki
- Division of Ultrahigh Field MRI (T.M., K.T., M.S.), Institute for Biomedical Sciences, Iwate Medical University School of Medicine, Morioka, Japan
| | - Y Kubo
- From the Department of Neurosurgery (S.T., Y.K., K.S., S.F., K.C., K.O.)
| | - K Setta
- From the Department of Neurosurgery (S.T., Y.K., K.S., S.F., K.C., K.O.)
| | - S Fujiwara
- From the Department of Neurosurgery (S.T., Y.K., K.S., S.F., K.C., K.O.)
| | - K Chida
- From the Department of Neurosurgery (S.T., Y.K., K.S., S.F., K.C., K.O.)
| | - K Ogasawara
- From the Department of Neurosurgery (S.T., Y.K., K.S., S.F., K.C., K.O.)
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7
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Hansson B, Simic M, Olsrud J, Markenroth Bloch K, Owman T, Sundgren PC, Björkman-Burtscher IM. MR-safety in clinical practice at 7T: Evaluation of a multistep screening process in 1819 subjects. Radiography (Lond) 2021; 28:454-459. [PMID: 34973869 DOI: 10.1016/j.radi.2021.12.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Revised: 12/01/2021] [Accepted: 12/15/2021] [Indexed: 11/18/2022]
Abstract
INTRODUCTION MR facilities must implement and maintain adequate screening and safety procedures to ensure safety during MR examinations. The aim of this study was to evaluate a multi-step MR safety screening process used at a 7T facility regarding incidence of different types of safety risks detected during the safety procedure. METHODS Subjects scheduled for an MR examination and having entered the 7T facility during 2016-2019 underwent a pre-defined multi-step MR safety screening process. Screening documentation of 1819 included subjects was reviewed, and risks identified during the different screening steps were compiled. These data were also related to documented decisions made by a 7T MR safety committee and reported MR safety incidents. RESULTS Passive or active implants (n = 315) were identified in a screening form and/or an additional documented interview in 305 subjects. Additional information not previously self-reported by the subject, regarding implants necessitating safety decisions performed by the staff was revealed in the documented interview in 102 subjects (106 items). In total, the 7T MR safety committee documented a decision in 36 (2%) of the included subjects. All of these subjects were finally cleared for scanning. CONCLUSION A multi-step screening process allows a thorough MR screening of subjects, avoiding safety incidents. Different steps in the process allow awareness to rise and items to be detected that were missed in earlier steps. IMPLICATIONS FOR PRACTICE Safety questions posed at a single timepoint during an MR screening process might not reveal all safety risks. Repetition and rephrasing of screening questions leads to increased detection of safety risks. This could be effectively mitigated by a multi-step screening process. A multi-disciplinary safety committee is efficient at short notice responding to unexpected safety issues.
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Affiliation(s)
- B Hansson
- Department of Medical Imaging and Physiology, Skåne University Hospital, Lund, Sweden; Department of Diagnostic Radiology, Clinical Sciences, Lund University, Lund, Sweden.
| | - M Simic
- Karolinska University Hospital, Solna Stockholm, Sweden
| | - J Olsrud
- Department of Diagnostic Radiology, Clinical Sciences, Lund University, Lund, Sweden
| | | | - T Owman
- Department of Medical Imaging and Physiology, Skåne University Hospital, Lund, Sweden; Department of Diagnostic Radiology, Clinical Sciences, Lund University, Lund, Sweden
| | - P C Sundgren
- Department of Medical Imaging and Physiology, Skåne University Hospital, Lund, Sweden; Department of Diagnostic Radiology, Clinical Sciences, Lund University, Lund, Sweden; Lund University Bioimaging Center (LBIC), Lund University, Lund, Sweden
| | - I M Björkman-Burtscher
- Department of Medical Imaging and Physiology, Skåne University Hospital, Lund, Sweden; Department of Diagnostic Radiology, Clinical Sciences, Lund University, Lund, Sweden; Department of Radiology, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg and Sahlgrenska University Hospital, Gothenburg, Sweden
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8
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Ong N, Zailan I, Tandon A. Imaging update in arthroplasty. J Clin Orthop Trauma 2021; 23:101649. [PMID: 34777990 PMCID: PMC8577440 DOI: 10.1016/j.jcot.2021.101649] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/09/2021] [Accepted: 10/12/2021] [Indexed: 11/20/2022] Open
Abstract
Imaging of metal implants has historically been difficult, regardless of the applied modality. The number of primary arthroplasties is increasing over the years. With it, we expect the number of symptomatic complications to increase as well. Acquiring accurate imaging for diagnosis and treatment planning for these cases is of paramount importance. Significant advancements have been made to reduce artifacts, leading to better imaging representation of arthroplasty. This review article would give a background on the current ways of imaging arthroplasty and metal implants, covering recent advances in imaging techniques.
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Affiliation(s)
| | | | - Ankit Tandon
- Tan Tock Seng Hospital, Singapore
- Corresponding author.
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9
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Abstract
Food and Drug Administration approval of 7T MR imaging allows ultrahigh-field neuroimaging to extend from the research realm into the clinical realm. Increased signal is clinically advantageous for smaller voxels and thereby high spatial resolution imaging, with additional advantages of increased tissue contrast. Susceptibility, time-of-flight signal, and blood oxygen level-dependent signal also have favorable clinical benefit from 7T. This article provides a survey of clinical cases showcasing some advantages of 7T.
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10
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Vachha B, Huang SY. MRI with ultrahigh field strength and high-performance gradients: challenges and opportunities for clinical neuroimaging at 7 T and beyond. Eur Radiol Exp 2021; 5:35. [PMID: 34435246 PMCID: PMC8387544 DOI: 10.1186/s41747-021-00216-2] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Accepted: 03/30/2021] [Indexed: 12/12/2022] Open
Abstract
Research in ultrahigh magnetic field strength combined with ultrahigh and ultrafast gradient technology has provided enormous gains in sensitivity, resolution, and contrast for neuroimaging. This article provides an overview of the technical advantages and challenges of performing clinical neuroimaging studies at ultrahigh magnetic field strength combined with ultrahigh and ultrafast gradient technology. Emerging clinical applications of 7-T MRI and state-of-the-art gradient systems equipped with up to 300 mT/m gradient strength are reviewed, and the impact and benefits of such advances to anatomical, structural and functional MRI are discussed in a variety of neurological conditions. Finally, an outlook and future directions for ultrahigh field MRI combined with ultrahigh and ultrafast gradient technology in neuroimaging are examined.
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Affiliation(s)
- Behroze Vachha
- Department of Radiology, Memorial Sloan Kettering Cancer Center, 1275 York Ave, New York, NY, 10065, USA
| | - Susie Y Huang
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, 149 13th Street, Room 2301, Charlestown, MA, 02129, USA.
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11
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Cosottini M, Roccatagliata L. Neuroimaging at 7 T: are we ready for clinical transition? Eur Radiol Exp 2021; 5:37. [PMID: 34435257 PMCID: PMC8387509 DOI: 10.1186/s41747-021-00234-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Accepted: 07/19/2021] [Indexed: 12/23/2022] Open
Abstract
In the last 20 years, ultra-high field (UHF) magnetic resonance imaging (MRI) has become an outstanding research tool for the study of the human brain, with 90 of these scanners installed today, worldwide. The recent clearances from regulatory bodies in the USA and Europe to 7-T clinical systems have set the ground for a transition from pure research applications to research and clinical use of these systems. As today, UFH neuroimaging is demonstrating clinical value and, given the importance of this topic for both preclinical scientists and clinical neuroradiologists, European Radiology Experimental is launching a thematic series entitled "7-T neuro MRI: from research to clinic", consisting of peer-reviewed articles, invited or spontaneously submitted, on topics selected by the guest editors, describing the state of the art of UHF MRI neuroimaging across different pathologies, as well as related clinical applications. In this editorial, we discuss some of the challenges related to the clinical use of 7-T scanners and the strengths and weaknesses of clinical imaging at UHF.
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Affiliation(s)
- Mirco Cosottini
- Department of Translational Research On New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy
| | - Luca Roccatagliata
- Department of Health Sciences (DISSAL), University of Genoa, Via Pastore 1, 16132, Genoa, Italy.
- Department of Neuroradiology, Ospedale Policlinico San Martino IRCCS, Genoa, Italy.
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12
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Abstract
After introduction of the first human 7 tesla (7T) system in 1999, 7T MR systems have been employed as one of the most advanced platforms for human MR research for more than 20 years. Currently, two 7T MR models are approved for clinical use in the U.S.A. The approval facilitated introduction of the 7T system, summing up to around 100 worldwide. The approval in Japan is much awaited. As a clinical MR scanner, the 7T MR system is drawing attention in terms of safety.Several large-sized studies on bioeffects have been reported for vertigo, dizziness, motion disturbances, nausea, and others. Such effects might also be found in MR workers and researchers. Frequency and severity of reported bioeffects will be presented and discussed, including their variances. The high resonance frequency and shorter RF wavelength of 7T increase the concern about the safety. Homogeneous RF pulse excitation is difficult even for the brain, and a multi-channel parallel transmit (pTx) system is considered mandatory. However, pTx may create a hot spot, which makes the estimation of specific absorption rate (SAR) to be difficult. The stronger magnetic field of 7T causes a large force of displacement and heating on metallic implants or devices, and the scan of patients with them should not be conducted at 7T. However, there are some opinions that such patients might be scanned even at 7T, if certain criteria are met. This article provides a brief review on the effect of the static magnetic field on humans (MR subjects, workers, and researchers) and neurons, in addition to scan sound, SAR, and metal implants and devices. Understanding and avoiding adverse effects will contribute to the reduction in safety risks and the prevention of incidents.
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Affiliation(s)
- Tomohisa Okada
- Human Brain Research Center, Graduate School of Medicine, Kyoto University
| | - Thai Akasaka
- Human Brain Research Center, Graduate School of Medicine, Kyoto University
| | - Dinh Hd Thuy
- Human Brain Research Center, Graduate School of Medicine, Kyoto University
| | - Tadashi Isa
- Human Brain Research Center, Graduate School of Medicine, Kyoto University
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13
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Fagan AJ, Bitz AK, Björkman-Burtscher IM, Collins CM, Kimbrell V, Raaijmakers AJ. 7T MR Safety. J Magn Reson Imaging 2021; 53:333-346. [PMID: 32830900 PMCID: PMC8170917 DOI: 10.1002/jmri.27319] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Revised: 07/21/2020] [Accepted: 07/22/2020] [Indexed: 12/11/2022] Open
Abstract
Magnetic resonance imaging and spectroscopy (MRI/MRS) at 7T represents an exciting advance in MR technology, with intriguing possibilities to enhance image spatial, spectral, and contrast resolution. To ensure the safe use of this technology while still harnessing its potential, clinical staff and researchers need to be cognizant of some safety concerns arising from the increased magnetic field strength and higher Larmor frequency. The higher static magnetic fields give rise to enhanced transient bioeffects and an increased risk of adverse incidents related to electrically conductive implants. Many technical challenges remain and the continuing rapid pace of development of 7T MRI/MRS is likely to present further challenges to ensuring safety of this technology in the years ahead. The recent regulatory clearance for clinical diagnostic imaging at 7T will likely increase the installed base of 7T systems, particularly in hospital environments with little prior ultrahigh-field MR experience. Informed risk/benefit analyses will be required, particularly where implant manufacturer-published 7T safety guidelines for implants are unavailable. On behalf of the International Society for Magnetic Resonance in Medicine, the aim of this article is to provide a reference document to assist institutions developing local institutional policies and procedures that are specific to the safe operation of 7T MRI/MRS. Details of current 7T technology and the physics underpinning its functionality are reviewed, with the aim of supporting efforts to expand the use of 7T MRI/MRS in both research and clinical environments. Current gaps in knowledge are also identified, where additional research and development are required. Level of Evidence 5 Technical Efficacy 2 J. MAGN. RESON. IMAGING 2021;53:333-346.
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Affiliation(s)
- Andrew J. Fagan
- Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA
| | - Andreas K. Bitz
- Faculty of Electrical Engineering and Information Technology, FH Aachen - University of Applied Sciences, Aachen, Germany
| | - Isabella M. Björkman-Burtscher
- Department of Radiology, University of Gothenburg, Sahlgrenska Academy, Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Christopher M. Collins
- Center for Advanced Imaging Innovation and Research, NYU Langone Medical Center, New York, New York, USA
| | - Vera Kimbrell
- Department of Radiology, Brigham and Women’s Hospital, Boston, Massachusetts, USA
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14
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Barisano G, Law M, Custer RM, Toga AW, Sepehrband F. Perivascular Space Imaging at Ultrahigh Field MR Imaging. Magn Reson Imaging Clin N Am 2020; 29:67-75. [PMID: 33237016 DOI: 10.1016/j.mric.2020.09.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The recent Food and Drug Administration approval of 7 T MR imaging scanners for clinical use has introduced the possibility to study the brain not only in physiologic but also in pathologic conditions at ultrahigh field (UHF). Because UHF MR imaging offers higher signal-to-noise ratio and spatial resolution compared with lower field clinical scanners, the benefits of UHF MR imaging are particularly evident for imaging small anatomic structures, such as the cerebral perivascular spaces (PVS). In this article, the authors describe the application of UHF MR imaging for the investigation of PVS.
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Affiliation(s)
- Giuseppe Barisano
- Neuroscience Graduate Program, University of Southern California, 2025 Zonal Ave, Los Angeles, CA 90033, USA.
| | - Meng Law
- Department of Neuroscience, Central Clinical School, Monash University, The Alfred Health, Level 6, 99 Commercial Road, Melbourne, Victoria 3004, Australia
| | - Rachel M Custer
- Laboratory of Neuro Imaging, Stevens Neuroimaging and Informatics Institute, Keck School of Medicine, University of Southern California, 2025 Zonal Ave, Los Angeles, CA 90033, USA
| | - Arthur W Toga
- Laboratory of Neuro Imaging, Stevens Neuroimaging and Informatics Institute, Keck School of Medicine, University of Southern California, 2025 Zonal Ave, Los Angeles, CA 90033, USA
| | - Farshid Sepehrband
- Laboratory of Neuro Imaging, Stevens Neuroimaging and Informatics Institute, Keck School of Medicine, University of Southern California, 2025 Zonal Ave, Los Angeles, CA 90033, USA
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15
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Abstract
Regulatory approval of ultrahigh field (UHF) MR imaging scanners for clinical use has opened new opportunities for musculoskeletal imaging applications. UHF MR imaging has unique advantages in terms of signal-to-noise ratio, contrast-to-noise ratio, spectral resolution, and multinuclear applications, thus providing unique information not available at lower field strengths. But UHF also comes with a set of technical challenges that are yet to be resolved and may not be suitable for all imaging applications. This review focuses on the latest research in musculoskeletal MR imaging applications at UHF including morphologic imaging, T2, T2∗, and T1ρ mapping, chemical exchange saturation transfer, sodium imaging, and phosphorus spectroscopy imaging applications.
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16
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Fagan AJ, Amrami KK, Welker KM, Frick MA, Felmlee JP, Watson RE. Magnetic Resonance Safety in the 7T Environment. Magn Reson Imaging Clin N Am 2020; 28:573-582. [PMID: 33040997 DOI: 10.1016/j.mric.2020.07.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The arrival of 7T MR imaging into the clinic represents a significant step-change in MR technology. This article describes safety concerns associated with imaging at 7T, including the increased magnetic forces on magnetic objects at 7T and the interaction of the 300 MHz (Larmor) radiofrequency energy with tissue in the body. A dedicated multidisciplinary 7T Safety team should develop safety policies and procedures to address these safety challenges and keep abreast of best practice in the field. The off-label imaging of implanted devices is discussed, and also the need for staff training to deal with complexities of patient handling and image interpretation.
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Affiliation(s)
- Andrew J Fagan
- Department of Radiology, Mayo Clinic, 200 First Street Southwest, Rochester, MN 55905, USA.
| | - Kimberly K Amrami
- Department of Radiology, Mayo Clinic, 200 First Street Southwest, Rochester, MN 55905, USA
| | - Kirk M Welker
- Department of Radiology, Mayo Clinic, 200 First Street Southwest, Rochester, MN 55905, USA
| | - Matthew A Frick
- Department of Radiology, Mayo Clinic, 200 First Street Southwest, Rochester, MN 55905, USA
| | - Joel P Felmlee
- Department of Radiology, Mayo Clinic, 200 First Street Southwest, Rochester, MN 55905, USA
| | - Robert E Watson
- Department of Radiology, Mayo Clinic, 200 First Street Southwest, Rochester, MN 55905, USA
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17
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Boutet A, Chow CT, Narang K, Elias GJB, Neudorfer C, Germann J, Ranjan M, Loh A, Martin AJ, Kucharczyk W, Steele CJ, Hancu I, Rezai AR, Lozano AM. Improving Safety of MRI in Patients with Deep Brain Stimulation Devices. Radiology 2020; 296:250-262. [PMID: 32573388 DOI: 10.1148/radiol.2020192291] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
MRI is a valuable clinical and research tool for patients undergoing deep brain stimulation (DBS). However, risks associated with imaging DBS devices have led to stringent regulations, limiting the clinical and research utility of MRI in these patients. The main risks in patients with DBS devices undergoing MRI are heating at the electrode tips, induced currents, implantable pulse generator dysfunction, and mechanical forces. Phantom model studies indicate that electrode tip heating remains the most serious risk for modern DBS devices. The absence of adverse events in patients imaged under DBS vendor guidelines for MRI demonstrates the general safety of MRI for patients with DBS devices. Moreover, recent work indicates that-given adequate safety data-patients may be imaged outside these guidelines. At present, investigators are primarily focused on improving DBS device and MRI safety through the development of tools, including safety simulation models. Existing guidelines provide a standardized framework for performing safe MRI in patients with DBS devices. It also highlights the possibility of expanding MRI as a tool for research and clinical care in these patients going forward.
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Affiliation(s)
- Alexandre Boutet
- From the University Health Network, Toronto, Canada (A.B., C.T.C., K.N., G.J.B.E., C.N., J.G., A.L., W.K., A.M.L.); Joint Department of Medical Imaging, University of Toronto, Toronto, Canada (A.B., W.K.); Department of Neurosurgery, West Virginia University, Morgantown, WVa (M.R., A.R.R.); Department of Neurosurgery, Rockefeller Neuroscience Institute, Morgantown, WVa (M.R., A.R.R.); Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, Calif (A.J.M.); Department of Psychology, Concordia University, Montreal, Canada (C.J.S.); Department of Neurology, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany (C.J.S.); Center for Scientific Review, National Institutes of Health, Bethesda, Md (I.H.); and Division of Neurosurgery, Department of Surgery, Toronto Western Hospital and University of Toronto, 399 Bathurst St, WW 4-437, Toronto, ON, Canada M5T 2S8 (A.M.L.)
| | - Clement T Chow
- From the University Health Network, Toronto, Canada (A.B., C.T.C., K.N., G.J.B.E., C.N., J.G., A.L., W.K., A.M.L.); Joint Department of Medical Imaging, University of Toronto, Toronto, Canada (A.B., W.K.); Department of Neurosurgery, West Virginia University, Morgantown, WVa (M.R., A.R.R.); Department of Neurosurgery, Rockefeller Neuroscience Institute, Morgantown, WVa (M.R., A.R.R.); Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, Calif (A.J.M.); Department of Psychology, Concordia University, Montreal, Canada (C.J.S.); Department of Neurology, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany (C.J.S.); Center for Scientific Review, National Institutes of Health, Bethesda, Md (I.H.); and Division of Neurosurgery, Department of Surgery, Toronto Western Hospital and University of Toronto, 399 Bathurst St, WW 4-437, Toronto, ON, Canada M5T 2S8 (A.M.L.)
| | - Keshav Narang
- From the University Health Network, Toronto, Canada (A.B., C.T.C., K.N., G.J.B.E., C.N., J.G., A.L., W.K., A.M.L.); Joint Department of Medical Imaging, University of Toronto, Toronto, Canada (A.B., W.K.); Department of Neurosurgery, West Virginia University, Morgantown, WVa (M.R., A.R.R.); Department of Neurosurgery, Rockefeller Neuroscience Institute, Morgantown, WVa (M.R., A.R.R.); Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, Calif (A.J.M.); Department of Psychology, Concordia University, Montreal, Canada (C.J.S.); Department of Neurology, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany (C.J.S.); Center for Scientific Review, National Institutes of Health, Bethesda, Md (I.H.); and Division of Neurosurgery, Department of Surgery, Toronto Western Hospital and University of Toronto, 399 Bathurst St, WW 4-437, Toronto, ON, Canada M5T 2S8 (A.M.L.)
| | - Gavin J B Elias
- From the University Health Network, Toronto, Canada (A.B., C.T.C., K.N., G.J.B.E., C.N., J.G., A.L., W.K., A.M.L.); Joint Department of Medical Imaging, University of Toronto, Toronto, Canada (A.B., W.K.); Department of Neurosurgery, West Virginia University, Morgantown, WVa (M.R., A.R.R.); Department of Neurosurgery, Rockefeller Neuroscience Institute, Morgantown, WVa (M.R., A.R.R.); Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, Calif (A.J.M.); Department of Psychology, Concordia University, Montreal, Canada (C.J.S.); Department of Neurology, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany (C.J.S.); Center for Scientific Review, National Institutes of Health, Bethesda, Md (I.H.); and Division of Neurosurgery, Department of Surgery, Toronto Western Hospital and University of Toronto, 399 Bathurst St, WW 4-437, Toronto, ON, Canada M5T 2S8 (A.M.L.)
| | - Clemens Neudorfer
- From the University Health Network, Toronto, Canada (A.B., C.T.C., K.N., G.J.B.E., C.N., J.G., A.L., W.K., A.M.L.); Joint Department of Medical Imaging, University of Toronto, Toronto, Canada (A.B., W.K.); Department of Neurosurgery, West Virginia University, Morgantown, WVa (M.R., A.R.R.); Department of Neurosurgery, Rockefeller Neuroscience Institute, Morgantown, WVa (M.R., A.R.R.); Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, Calif (A.J.M.); Department of Psychology, Concordia University, Montreal, Canada (C.J.S.); Department of Neurology, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany (C.J.S.); Center for Scientific Review, National Institutes of Health, Bethesda, Md (I.H.); and Division of Neurosurgery, Department of Surgery, Toronto Western Hospital and University of Toronto, 399 Bathurst St, WW 4-437, Toronto, ON, Canada M5T 2S8 (A.M.L.)
| | - Jürgen Germann
- From the University Health Network, Toronto, Canada (A.B., C.T.C., K.N., G.J.B.E., C.N., J.G., A.L., W.K., A.M.L.); Joint Department of Medical Imaging, University of Toronto, Toronto, Canada (A.B., W.K.); Department of Neurosurgery, West Virginia University, Morgantown, WVa (M.R., A.R.R.); Department of Neurosurgery, Rockefeller Neuroscience Institute, Morgantown, WVa (M.R., A.R.R.); Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, Calif (A.J.M.); Department of Psychology, Concordia University, Montreal, Canada (C.J.S.); Department of Neurology, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany (C.J.S.); Center for Scientific Review, National Institutes of Health, Bethesda, Md (I.H.); and Division of Neurosurgery, Department of Surgery, Toronto Western Hospital and University of Toronto, 399 Bathurst St, WW 4-437, Toronto, ON, Canada M5T 2S8 (A.M.L.)
| | - Manish Ranjan
- From the University Health Network, Toronto, Canada (A.B., C.T.C., K.N., G.J.B.E., C.N., J.G., A.L., W.K., A.M.L.); Joint Department of Medical Imaging, University of Toronto, Toronto, Canada (A.B., W.K.); Department of Neurosurgery, West Virginia University, Morgantown, WVa (M.R., A.R.R.); Department of Neurosurgery, Rockefeller Neuroscience Institute, Morgantown, WVa (M.R., A.R.R.); Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, Calif (A.J.M.); Department of Psychology, Concordia University, Montreal, Canada (C.J.S.); Department of Neurology, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany (C.J.S.); Center for Scientific Review, National Institutes of Health, Bethesda, Md (I.H.); and Division of Neurosurgery, Department of Surgery, Toronto Western Hospital and University of Toronto, 399 Bathurst St, WW 4-437, Toronto, ON, Canada M5T 2S8 (A.M.L.)
| | - Aaron Loh
- From the University Health Network, Toronto, Canada (A.B., C.T.C., K.N., G.J.B.E., C.N., J.G., A.L., W.K., A.M.L.); Joint Department of Medical Imaging, University of Toronto, Toronto, Canada (A.B., W.K.); Department of Neurosurgery, West Virginia University, Morgantown, WVa (M.R., A.R.R.); Department of Neurosurgery, Rockefeller Neuroscience Institute, Morgantown, WVa (M.R., A.R.R.); Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, Calif (A.J.M.); Department of Psychology, Concordia University, Montreal, Canada (C.J.S.); Department of Neurology, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany (C.J.S.); Center for Scientific Review, National Institutes of Health, Bethesda, Md (I.H.); and Division of Neurosurgery, Department of Surgery, Toronto Western Hospital and University of Toronto, 399 Bathurst St, WW 4-437, Toronto, ON, Canada M5T 2S8 (A.M.L.)
| | - Alastair J Martin
- From the University Health Network, Toronto, Canada (A.B., C.T.C., K.N., G.J.B.E., C.N., J.G., A.L., W.K., A.M.L.); Joint Department of Medical Imaging, University of Toronto, Toronto, Canada (A.B., W.K.); Department of Neurosurgery, West Virginia University, Morgantown, WVa (M.R., A.R.R.); Department of Neurosurgery, Rockefeller Neuroscience Institute, Morgantown, WVa (M.R., A.R.R.); Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, Calif (A.J.M.); Department of Psychology, Concordia University, Montreal, Canada (C.J.S.); Department of Neurology, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany (C.J.S.); Center for Scientific Review, National Institutes of Health, Bethesda, Md (I.H.); and Division of Neurosurgery, Department of Surgery, Toronto Western Hospital and University of Toronto, 399 Bathurst St, WW 4-437, Toronto, ON, Canada M5T 2S8 (A.M.L.)
| | - Walter Kucharczyk
- From the University Health Network, Toronto, Canada (A.B., C.T.C., K.N., G.J.B.E., C.N., J.G., A.L., W.K., A.M.L.); Joint Department of Medical Imaging, University of Toronto, Toronto, Canada (A.B., W.K.); Department of Neurosurgery, West Virginia University, Morgantown, WVa (M.R., A.R.R.); Department of Neurosurgery, Rockefeller Neuroscience Institute, Morgantown, WVa (M.R., A.R.R.); Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, Calif (A.J.M.); Department of Psychology, Concordia University, Montreal, Canada (C.J.S.); Department of Neurology, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany (C.J.S.); Center for Scientific Review, National Institutes of Health, Bethesda, Md (I.H.); and Division of Neurosurgery, Department of Surgery, Toronto Western Hospital and University of Toronto, 399 Bathurst St, WW 4-437, Toronto, ON, Canada M5T 2S8 (A.M.L.)
| | - Christopher J Steele
- From the University Health Network, Toronto, Canada (A.B., C.T.C., K.N., G.J.B.E., C.N., J.G., A.L., W.K., A.M.L.); Joint Department of Medical Imaging, University of Toronto, Toronto, Canada (A.B., W.K.); Department of Neurosurgery, West Virginia University, Morgantown, WVa (M.R., A.R.R.); Department of Neurosurgery, Rockefeller Neuroscience Institute, Morgantown, WVa (M.R., A.R.R.); Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, Calif (A.J.M.); Department of Psychology, Concordia University, Montreal, Canada (C.J.S.); Department of Neurology, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany (C.J.S.); Center for Scientific Review, National Institutes of Health, Bethesda, Md (I.H.); and Division of Neurosurgery, Department of Surgery, Toronto Western Hospital and University of Toronto, 399 Bathurst St, WW 4-437, Toronto, ON, Canada M5T 2S8 (A.M.L.)
| | - Ileana Hancu
- From the University Health Network, Toronto, Canada (A.B., C.T.C., K.N., G.J.B.E., C.N., J.G., A.L., W.K., A.M.L.); Joint Department of Medical Imaging, University of Toronto, Toronto, Canada (A.B., W.K.); Department of Neurosurgery, West Virginia University, Morgantown, WVa (M.R., A.R.R.); Department of Neurosurgery, Rockefeller Neuroscience Institute, Morgantown, WVa (M.R., A.R.R.); Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, Calif (A.J.M.); Department of Psychology, Concordia University, Montreal, Canada (C.J.S.); Department of Neurology, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany (C.J.S.); Center for Scientific Review, National Institutes of Health, Bethesda, Md (I.H.); and Division of Neurosurgery, Department of Surgery, Toronto Western Hospital and University of Toronto, 399 Bathurst St, WW 4-437, Toronto, ON, Canada M5T 2S8 (A.M.L.)
| | - Ali R Rezai
- From the University Health Network, Toronto, Canada (A.B., C.T.C., K.N., G.J.B.E., C.N., J.G., A.L., W.K., A.M.L.); Joint Department of Medical Imaging, University of Toronto, Toronto, Canada (A.B., W.K.); Department of Neurosurgery, West Virginia University, Morgantown, WVa (M.R., A.R.R.); Department of Neurosurgery, Rockefeller Neuroscience Institute, Morgantown, WVa (M.R., A.R.R.); Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, Calif (A.J.M.); Department of Psychology, Concordia University, Montreal, Canada (C.J.S.); Department of Neurology, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany (C.J.S.); Center for Scientific Review, National Institutes of Health, Bethesda, Md (I.H.); and Division of Neurosurgery, Department of Surgery, Toronto Western Hospital and University of Toronto, 399 Bathurst St, WW 4-437, Toronto, ON, Canada M5T 2S8 (A.M.L.)
| | - Andres M Lozano
- From the University Health Network, Toronto, Canada (A.B., C.T.C., K.N., G.J.B.E., C.N., J.G., A.L., W.K., A.M.L.); Joint Department of Medical Imaging, University of Toronto, Toronto, Canada (A.B., W.K.); Department of Neurosurgery, West Virginia University, Morgantown, WVa (M.R., A.R.R.); Department of Neurosurgery, Rockefeller Neuroscience Institute, Morgantown, WVa (M.R., A.R.R.); Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, Calif (A.J.M.); Department of Psychology, Concordia University, Montreal, Canada (C.J.S.); Department of Neurology, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany (C.J.S.); Center for Scientific Review, National Institutes of Health, Bethesda, Md (I.H.); and Division of Neurosurgery, Department of Surgery, Toronto Western Hospital and University of Toronto, 399 Bathurst St, WW 4-437, Toronto, ON, Canada M5T 2S8 (A.M.L.)
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Image Artifact Management for Clinical Magnetic Resonance Imaging on a 7 T Scanner Using Single-Channel Radiofrequency Transmit Mode. Invest Radiol 2020; 54:781-791. [PMID: 31503079 DOI: 10.1097/rli.0000000000000598] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
OBJECTIVES The aim of this work was to devise mitigation strategies for addressing a range of image artifacts on a clinical 7 T magnetic resonance imaging scanner using the regulatory-approved single-channel radiofrequency transmit mode and vendor-supplied radiofrequency coils to facilitate clinical scanning within reasonable scan times. MATERIALS AND METHODS Optimized imaging sequence protocols were developed for routine musculoskeletal knee and neurological imaging. Sources of severe image nonuniformities were identified, and mitigation strategies were devised. A range of custom-made high permittivity dielectric pads were used to compensate for B1 and B1 inhomogeneities, and also for magnetic susceptibility-induced signal dropouts particularly in the basal regions of the temporal lobes and in the cerebellum. RESULTS Significant improvements in image uniformity were obtained using dielectric pads in the knee and brain. A combination of small voxels, reduced field of view B0 shimming, and high in-plane parallel imaging factors helped to minimize signal loss in areas of high susceptibility-induced field distortions. The high inherent signal-to-noise ratio at 7 T allowed for high receiver bandwidths and thin slices to minimize chemical shift artifacts. Intermittent artifacts due to radiofrequency inversion pulse limitations (power, bandwidth) were minimized with dielectric pads. A patient with 2 implanted metallic cranial fixation devices located within the radiofrequency transmit field was successfully imaged, with minimal image geometric distortions. CONCLUSIONS Challenges relating to severe image artifacts at 7 T using single-channel radiofrequency transmit functionality in the knee and brain were overcome using the approaches described in this article. The resultant high diagnostic image quality paves the way for incorporation of this technology into the routine clinical workflow. Further developmental efforts are required to expand the range of applications to other anatomical areas, and to expand the evidence- and knowledge-base relating to the safety of scanning patients with implanted metallic devices.
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19
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Tumor T2 signal intensity and stalk angulation correlates with endocrine status in pituitary adenoma patients: a quantitative 7 tesla MRI study. Neuroradiology 2020; 62:473-482. [PMID: 31925468 DOI: 10.1007/s00234-019-02352-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Accepted: 12/22/2019] [Indexed: 12/22/2022]
Abstract
PURPOSE Pituitary adenomas are common CNS tumors that can cause endocrine dysfunction due to hormone oversecretion and by mass effect on the normal gland. The study of pituitary adenomas and adjacent sellar anatomy with high-resolution 7 T MRI may further characterize endocrine dysfunction. The purpose of this study was to determine the efficacy of 7 T MRI in identifying radiological markers for endocrine function. METHODS MR images obtained in 23 patients with pituitary adenomas were reviewed by consensus between three neuroradiologists. Landmarks and criteria were devised to measure radiological features of stalk, tumor, and normal gland. Fischer's exact tests and nominal logistic regression were performed. RESULTS Mean cross-sectional area of the stalk just below the infundibular recess was 6.3 ± 3.7 mm2. Mean curvature and deviation angles were 34.2° ± 23.2° and 29.7° ± 17.3°, respectively. Knosp scores obtained differed between 7 T and lower field strength scans (P < 0.0001 [right] and P = 0.0006 [left]). Ability to characterize tumor was rated higher at 7 T compared with lower field MRI, P = 0.05. Confidence in visualizing normal gland was also higher using 7 T MRI, P = 0.036. The six hormone-secreting tumors had higher corrected T2 mean SI than non-secreting tumors (2.54 vs. - 0.38, P = 0.0196). Seven patients had preoperative hypopituitarism and had significantly greater stalk curvature angles than patients without hypopituitarism (71.7° vs. 36.55°, P = 0.027). CONCLUSION Radiological characterization of pituitary adenomas and adjacent native pituitary tissue may benefit with the use of 7 T MRI. Corrected T2 SI of tumor may be a sensitive predictor of hormonal secretion and may be useful in the diagnostic work-up for pituitary adenoma. 7 T MRI may be valuable in identifying markers of endocrine function in patients with pituitary adenomas. Our results indicate that hormone-secreting tumors have higher T2-weighted SI and tumors associated with preoperative hypopituitarism have greater stalk curvature angles.
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20
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Heinrich A, Dorschel J, Mohammad Mashoor M, Guttler F, Teichgraber U. Development of an Apparatus for Digital Measurement of Magnetically Induced Torque on Medical Implants to Facilitate the Application of the ASTM F2213 Standard. IEEE Trans Biomed Eng 2019; 66:3420-3425. [DOI: 10.1109/tbme.2019.2905236] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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21
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Abstract
BACKGROUND It can be expected that the number of 7 T MRI systems for clinical use will increase in the future. On the other hand, almost no medical implant has been labeled MR conditional for 7 T, so far, leaving the question of implant safety unanswered to the MR operator. METHODS In principle, the same interactions between magnetizable and electric conductive material apply at 7 T as known at lower magnetic field strengths. However, there are a few important differences that need to be taken into account to perform a profound risk-benefit analysis. After a more general introduction of technical differences between 3 and 7 T systems, the article will focus mainly on safety assessments with regard to interactions between implant and radiofrequency (RF) transmit fields. In addition, strategies to ensure access at 7 T will be discussed. RESULTS OF PRACTICAL RELEVANCE Besides hazards due to the magnetic force which can be up to 2.3 times stronger at 7 T compared to 3 T, increased risks of RF-induced tissue heating are the most critical aspects. The resonant-length of an implant at 7 T is about 5 cm. Other than at 3 T, MR systems at 7 T are less standardized. Especially with regard to the RF transmit coil and transmission methods used, substantial differences need to be expected. Hence, it is important to critically question published safety assessments of implants and to have a thorough discussion about how this relates to the individual exposure scenario. For nonmagnetic implants without a dedicated 7 T safety evaluation, but which are 3 T MR conditional and have a certain minimum distance to the RF transmit coil, a consensus recommendation from the national network German Ultrahigh Field Imaging (GUFI) may be helpful.
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Affiliation(s)
- O Kraff
- Erwin L. Hahn Institute for MR Imaging, Universität Duisburg-Essen, Kokereiallee 7, 45141, Essen, Deutschland.
| | - H H Quick
- Erwin L. Hahn Institute for MR Imaging, Universität Duisburg-Essen, Kokereiallee 7, 45141, Essen, Deutschland.,Hochfeld- und Hybride MR-Bildgebung, Universitätsklinikum Essen, Essen, Deutschland
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22
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Hoff MN, McKinney A, Shellock FG, Rassner U, Gilk T, Watson RE, Greenberg TD, Froelich J, Kanal E. Safety Considerations of 7-T MRI in Clinical Practice. Radiology 2019; 292:509-518. [PMID: 31310177 DOI: 10.1148/radiol.2019182742] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Although 7-T MRI has recently received approval for use in clinical patient care, there are distinct safety issues associated with this relatively high magnetic field. Forces on metallic implants and radiofrequency power deposition and heating are safety considerations at 7 T. Patient bioeffects such as vertigo, dizziness, false feelings of motion, nausea, nystagmus, magnetophosphenes, and electrogustatory effects are more common and potentially more pronounced at 7 T than at lower field strengths. Herein the authors review safety issues associated with 7-T MRI. The rationale for safety concerns at this field strength are discussed as well as potential approaches to mitigate risk to patients and health care professionals.
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Affiliation(s)
- Michael N Hoff
- From the Department of Radiology, University of Washington, 1959 NE Pacific St, Seattle, WA 98195-7117 (M.N.H.); Department of Radiology, University of Minnesota, Minneapolis, Minn (A.M., J.F.); Department of Clinical Physical Therapy, University of Southern California, Los Angeles, Calif (F.G.S.); Department of Radiology, University of Utah Health Sciences Center, Salt Lake City, Utah (U.R.); RADIOLOGY-Planning, Kansas City, Mo (T.G.); Department of Radiology, Mayo Clinic, Rochester, Minn (R.E.W.); G3 Global Group, Boulder, Colo, Mo (T.D.G.); and Department of Radiology, University of Pittsburgh Medical Center, Pittsburgh, Pa (E.K.)
| | - Alexander McKinney
- From the Department of Radiology, University of Washington, 1959 NE Pacific St, Seattle, WA 98195-7117 (M.N.H.); Department of Radiology, University of Minnesota, Minneapolis, Minn (A.M., J.F.); Department of Clinical Physical Therapy, University of Southern California, Los Angeles, Calif (F.G.S.); Department of Radiology, University of Utah Health Sciences Center, Salt Lake City, Utah (U.R.); RADIOLOGY-Planning, Kansas City, Mo (T.G.); Department of Radiology, Mayo Clinic, Rochester, Minn (R.E.W.); G3 Global Group, Boulder, Colo, Mo (T.D.G.); and Department of Radiology, University of Pittsburgh Medical Center, Pittsburgh, Pa (E.K.)
| | - Frank G Shellock
- From the Department of Radiology, University of Washington, 1959 NE Pacific St, Seattle, WA 98195-7117 (M.N.H.); Department of Radiology, University of Minnesota, Minneapolis, Minn (A.M., J.F.); Department of Clinical Physical Therapy, University of Southern California, Los Angeles, Calif (F.G.S.); Department of Radiology, University of Utah Health Sciences Center, Salt Lake City, Utah (U.R.); RADIOLOGY-Planning, Kansas City, Mo (T.G.); Department of Radiology, Mayo Clinic, Rochester, Minn (R.E.W.); G3 Global Group, Boulder, Colo, Mo (T.D.G.); and Department of Radiology, University of Pittsburgh Medical Center, Pittsburgh, Pa (E.K.)
| | - Ulrich Rassner
- From the Department of Radiology, University of Washington, 1959 NE Pacific St, Seattle, WA 98195-7117 (M.N.H.); Department of Radiology, University of Minnesota, Minneapolis, Minn (A.M., J.F.); Department of Clinical Physical Therapy, University of Southern California, Los Angeles, Calif (F.G.S.); Department of Radiology, University of Utah Health Sciences Center, Salt Lake City, Utah (U.R.); RADIOLOGY-Planning, Kansas City, Mo (T.G.); Department of Radiology, Mayo Clinic, Rochester, Minn (R.E.W.); G3 Global Group, Boulder, Colo, Mo (T.D.G.); and Department of Radiology, University of Pittsburgh Medical Center, Pittsburgh, Pa (E.K.)
| | - Tobias Gilk
- From the Department of Radiology, University of Washington, 1959 NE Pacific St, Seattle, WA 98195-7117 (M.N.H.); Department of Radiology, University of Minnesota, Minneapolis, Minn (A.M., J.F.); Department of Clinical Physical Therapy, University of Southern California, Los Angeles, Calif (F.G.S.); Department of Radiology, University of Utah Health Sciences Center, Salt Lake City, Utah (U.R.); RADIOLOGY-Planning, Kansas City, Mo (T.G.); Department of Radiology, Mayo Clinic, Rochester, Minn (R.E.W.); G3 Global Group, Boulder, Colo, Mo (T.D.G.); and Department of Radiology, University of Pittsburgh Medical Center, Pittsburgh, Pa (E.K.)
| | - Robert E Watson
- From the Department of Radiology, University of Washington, 1959 NE Pacific St, Seattle, WA 98195-7117 (M.N.H.); Department of Radiology, University of Minnesota, Minneapolis, Minn (A.M., J.F.); Department of Clinical Physical Therapy, University of Southern California, Los Angeles, Calif (F.G.S.); Department of Radiology, University of Utah Health Sciences Center, Salt Lake City, Utah (U.R.); RADIOLOGY-Planning, Kansas City, Mo (T.G.); Department of Radiology, Mayo Clinic, Rochester, Minn (R.E.W.); G3 Global Group, Boulder, Colo, Mo (T.D.G.); and Department of Radiology, University of Pittsburgh Medical Center, Pittsburgh, Pa (E.K.)
| | - Todd D Greenberg
- From the Department of Radiology, University of Washington, 1959 NE Pacific St, Seattle, WA 98195-7117 (M.N.H.); Department of Radiology, University of Minnesota, Minneapolis, Minn (A.M., J.F.); Department of Clinical Physical Therapy, University of Southern California, Los Angeles, Calif (F.G.S.); Department of Radiology, University of Utah Health Sciences Center, Salt Lake City, Utah (U.R.); RADIOLOGY-Planning, Kansas City, Mo (T.G.); Department of Radiology, Mayo Clinic, Rochester, Minn (R.E.W.); G3 Global Group, Boulder, Colo, Mo (T.D.G.); and Department of Radiology, University of Pittsburgh Medical Center, Pittsburgh, Pa (E.K.)
| | - Jerry Froelich
- From the Department of Radiology, University of Washington, 1959 NE Pacific St, Seattle, WA 98195-7117 (M.N.H.); Department of Radiology, University of Minnesota, Minneapolis, Minn (A.M., J.F.); Department of Clinical Physical Therapy, University of Southern California, Los Angeles, Calif (F.G.S.); Department of Radiology, University of Utah Health Sciences Center, Salt Lake City, Utah (U.R.); RADIOLOGY-Planning, Kansas City, Mo (T.G.); Department of Radiology, Mayo Clinic, Rochester, Minn (R.E.W.); G3 Global Group, Boulder, Colo, Mo (T.D.G.); and Department of Radiology, University of Pittsburgh Medical Center, Pittsburgh, Pa (E.K.)
| | - Emanuel Kanal
- From the Department of Radiology, University of Washington, 1959 NE Pacific St, Seattle, WA 98195-7117 (M.N.H.); Department of Radiology, University of Minnesota, Minneapolis, Minn (A.M., J.F.); Department of Clinical Physical Therapy, University of Southern California, Los Angeles, Calif (F.G.S.); Department of Radiology, University of Utah Health Sciences Center, Salt Lake City, Utah (U.R.); RADIOLOGY-Planning, Kansas City, Mo (T.G.); Department of Radiology, Mayo Clinic, Rochester, Minn (R.E.W.); G3 Global Group, Boulder, Colo, Mo (T.D.G.); and Department of Radiology, University of Pittsburgh Medical Center, Pittsburgh, Pa (E.K.)
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23
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Neuroimaging Technological Advancements for Targeting in Functional Neurosurgery. Curr Neurol Neurosci Rep 2019; 19:42. [DOI: 10.1007/s11910-019-0961-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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24
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Culo B, Valencerina S, Law M, Shellock FG. Assessment of metallic patient support devices and other items at 7-Tesla: Findings applied to 46 additional devices. Magn Reson Imaging 2019; 57:250-253. [DOI: 10.1016/j.mri.2018.11.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Accepted: 11/11/2018] [Indexed: 12/27/2022]
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25
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Barisano G, Culo B, Shellock FG, Sepehrband F, Martin K, Stevens M, Wang DJ, Toga AW, Law M. 7-Tesla MRI of the brain in a research subject with bilateral, total knee replacement implants: Case report and proposed safety guidelines. Magn Reson Imaging 2018; 57:313-316. [PMID: 30496792 DOI: 10.1016/j.mri.2018.11.016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2018] [Revised: 11/01/2018] [Accepted: 11/20/2018] [Indexed: 11/26/2022]
Abstract
Recently, the first 7-T MR system was approved for clinical use in the United States. Unfortunately, relatively few metallic implants have undergone testing to determine if they are acceptable or pose hazards to research subjects and patients at this ultra-high-field strength. Therefore, in lieu of not performing a research or clinical MRI exam at 7-T, the supervising physician may make a decision to scan the individual with an untested metallic implant based on an analysis of the risks vs. the benefits. We present a case report of a research subject with bilateral, total knee replacement implants that safely underwent MRI of the brain at 7-T and provide guidelines for healthcare professionals to follow in order to ensure safety in research subjects or patients with metallic implants referred for 7-T scans.
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Affiliation(s)
- Giuseppe Barisano
- Department of Radiology, Keck School of Medicine of University of Southern California, 1975 Zonal Ave, Los Angeles, CA 90033, United States of America; Stevens Neuroimaging and Informatics Institute, University of Southern California, 2025 Zonal Ave., Los Angeles, CA 90033, United States of America
| | - Bozena Culo
- Loyola Marymount University, 1 LMU Drive, Los Angeles, CA 90045, United States of America
| | - Frank G Shellock
- Department of Radiology, Keck School of Medicine of University of Southern California, 1975 Zonal Ave, Los Angeles, CA 90033, United States of America.
| | - Farshid Sepehrband
- Stevens Neuroimaging and Informatics Institute, University of Southern California, 2025 Zonal Ave., Los Angeles, CA 90033, United States of America
| | - Katherin Martin
- Stevens Neuroimaging and Informatics Institute, University of Southern California, 2025 Zonal Ave., Los Angeles, CA 90033, United States of America
| | - Mary Stevens
- Stevens Neuroimaging and Informatics Institute, University of Southern California, 2025 Zonal Ave., Los Angeles, CA 90033, United States of America
| | - Danny J Wang
- Stevens Neuroimaging and Informatics Institute, University of Southern California, 2025 Zonal Ave., Los Angeles, CA 90033, United States of America
| | - Arthur W Toga
- Stevens Neuroimaging and Informatics Institute, University of Southern California, 2025 Zonal Ave., Los Angeles, CA 90033, United States of America
| | - Meng Law
- Department of Radiology, Keck School of Medicine of University of Southern California, 1975 Zonal Ave, Los Angeles, CA 90033, United States of America
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26
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Barisano G, Sepehrband F, Ma S, Jann K, Cabeen R, Wang DJ, Toga AW, Law M. Clinical 7 T MRI: Are we there yet? A review about magnetic resonance imaging at ultra-high field. Br J Radiol 2018; 92:20180492. [PMID: 30359093 DOI: 10.1259/bjr.20180492] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
In recent years, ultra-high field MRI (7 T and above) has received more interest for clinical imaging. Indeed, a number of studies have shown the benefits from the application of this powerful tool not only for research purposes, but also in realms of improved diagnostics and patient management. The increased signal-to-noise ratio and higher spatial resolution compared with conventional and high-field clinical scanners allow imaging of small anatomical detail and subtle pathological findings. Furthermore, greater spectral resolution achieved at ultra-high field allows the resolution of metabolites for MR spectroscopic imaging. All these advantages have a significant impact on many neurological diseases, including multiple sclerosis, cerebrovascular disease, brain tumors, epilepsy and neurodegenerative diseases, in part because the pathology can be subtle and lesions small in these diseases, therefore having higher signal and resolution will help lesion detection. In this review, we discuss the main clinical neurological applications and some technical challenges which remain with ultra-high field MRI.
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Affiliation(s)
- Giuseppe Barisano
- 1 Department of Radiology, Keck Medical Center of University of Southern California , Los Angeles, CA , USA.,2 Stevens Neuroimaging and Informatics Institute, University of Southern California , Los Angeles, CA , USA
| | - Farshid Sepehrband
- 2 Stevens Neuroimaging and Informatics Institute, University of Southern California , Los Angeles, CA , USA
| | - Samantha Ma
- 2 Stevens Neuroimaging and Informatics Institute, University of Southern California , Los Angeles, CA , USA
| | - Kay Jann
- 2 Stevens Neuroimaging and Informatics Institute, University of Southern California , Los Angeles, CA , USA
| | - Ryan Cabeen
- 2 Stevens Neuroimaging and Informatics Institute, University of Southern California , Los Angeles, CA , USA
| | - Danny J Wang
- 2 Stevens Neuroimaging and Informatics Institute, University of Southern California , Los Angeles, CA , USA
| | - Arthur W Toga
- 2 Stevens Neuroimaging and Informatics Institute, University of Southern California , Los Angeles, CA , USA
| | - Meng Law
- 1 Department of Radiology, Keck Medical Center of University of Southern California , Los Angeles, CA , USA.,2 Stevens Neuroimaging and Informatics Institute, University of Southern California , Los Angeles, CA , USA
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Abstract
The literature within the last 10 years on MRI use in patients with orthopedic implants is reviewed. A literature search returned 15 relevant articles. Only 2 discussed pediatric patients. Overall, significant displacement of implants was infrequent. Radiofrequency-induced heating of implants differed among the studies, but most reported increases of less than 1°C. The authors conclude MRI is safe in patients with orthopedic implants because implant displacement and heating pose little risk to patients. A risk-to-benefit ratio is warranted, however, to assess the clinical utility and necessity of the study. Further research and individual assessment of implant properties and MRI-related interactions are warranted.
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28
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Yilmaz S, Adisen MZ. Ex Vivo Mercury Release from Dental Amalgam after 7.0-T and 1.5-T MRI. Radiology 2018; 288:799-803. [DOI: 10.1148/radiol.2018172597] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Selmi Yilmaz
- From the Department of Oral and Maxillofacial Radiology, Faculty of Dentistry, Akdeniz University, P.K. 10 Dumlupinar Bulvari Kampus, 07058 Konyaalti/Antalya, Turkey (S.Y.); and Department of Oral and Maxillofacial Radiology, Faculty of Dentistry, Kirikkale University, Kirikkale, Turkey (M.Z.A.)
| | - M. Zahit Adisen
- From the Department of Oral and Maxillofacial Radiology, Faculty of Dentistry, Akdeniz University, P.K. 10 Dumlupinar Bulvari Kampus, 07058 Konyaalti/Antalya, Turkey (S.Y.); and Department of Oral and Maxillofacial Radiology, Faculty of Dentistry, Kirikkale University, Kirikkale, Turkey (M.Z.A.)
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29
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Destruel A, O'Brien K, Jin J, Liu F, Barth M, Crozier S. Adaptive SAR mass-averaging framework to improve predictions of local RF heating near a hip implant for parallel transmit at 7 T. Magn Reson Med 2018; 81:615-627. [PMID: 30058186 DOI: 10.1002/mrm.27379] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Revised: 04/26/2018] [Accepted: 05/07/2018] [Indexed: 12/26/2022]
Abstract
PURPOSE Magnetic resonance imaging is used increasingly to scan patients with hip prostheses. We evaluated the reliability of 10 g-averaged specific absorption rate (SAR10g ) to predict radiofrequency (RF) heating in tissues surrounding a hip implant at 7 T in an 8-channel pTx hip coil. A new adaptive SAR mass-averaging method is proposed to improve the correlation between the distribution of mass-averaged SAR and that of tissue temperature. METHODS Currently, RF safety standards for implants are based on temperature instead of SAR, as SAR has not been introduced with regard to exposure scenarios with implants. In this manuscript, however, adaptive SAR is proposed for fast and reliable exposure evaluation with implants, after its correlation with tissue temperature is verified. A framework to calculate adaptive SAR mass-averaging was introduced, which uses a different averaging mass in tissues surrounding the implants and was designed to prevent the temperature from exceeding 39ºC. Predictions from SAR10g and adaptive SAR were compared with thermal simulations. RESULTS The SAR10g method failed to predict both the location and amplitude of heating in tissue near the metal implants. In some cases, the temperature far exceeded 39ºC even when SAR10g was only 70% of the maximum allowed 10 W/kg. The distributions of adaptive SAR and temperature matched in most of the configurations, and the temperature remained below 39ºC when adaptive SAR was constrained. CONCLUSION Adaptive SAR can accurately monitor RF heating and could be used for parallel transmit at 7 T to supplement current standards.
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Affiliation(s)
- Aurelien Destruel
- School of Information Technology and Electrical Engineering, University of Queensland, Australia.,Centre for Advanced Imaging, University of Queensland, Australia
| | - Kieran O'Brien
- Centre for Advanced Imaging, University of Queensland, Australia.,Siemens Healthcare Pty Ltd, Brisbane, Australia
| | - Jin Jin
- School of Information Technology and Electrical Engineering, University of Queensland, Australia.,Siemens Medical Solutions USA, Malvern, Pennsylvania.,Institute for Neuroimaging and Informatics, University of Southern California, Los Angeles, California
| | - Feng Liu
- School of Information Technology and Electrical Engineering, University of Queensland, Australia
| | - Markus Barth
- Centre for Advanced Imaging, University of Queensland, Australia
| | - Stuart Crozier
- School of Information Technology and Electrical Engineering, University of Queensland, Australia
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30
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Menon RG, Chang G, Regatte RR. The Emerging Role of 7 Tesla MRI in Musculoskeletal Imaging. CURRENT RADIOLOGY REPORTS 2018. [DOI: 10.1007/s40134-018-0286-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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31
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Song T, Xu Z, Iacono MI, Angelone LM, Rajan S. Retrospective analysis of RF heating measurements of passive medical implants. Magn Reson Med 2018; 80:2726-2730. [DOI: 10.1002/mrm.27346] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Revised: 04/13/2018] [Accepted: 04/14/2018] [Indexed: 12/17/2022]
Affiliation(s)
- Ting Song
- Food and Drug Administration, Center for Devices and Radiological Health; Silver Spring Maryland
| | - Zhiheng Xu
- Food and Drug Administration, Center for Devices and Radiological Health; Silver Spring Maryland
| | - Maria Ida Iacono
- Food and Drug Administration, Center for Devices and Radiological Health; Silver Spring Maryland
| | - Leonardo M. Angelone
- Food and Drug Administration, Center for Devices and Radiological Health; Silver Spring Maryland
| | - Sunder Rajan
- Food and Drug Administration, Center for Devices and Radiological Health; Silver Spring Maryland
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32
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Barry RL, Vannesjo SJ, By S, Gore JC, Smith SA. Spinal cord MRI at 7T. Neuroimage 2018; 168:437-451. [PMID: 28684332 PMCID: PMC5894871 DOI: 10.1016/j.neuroimage.2017.07.003] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2016] [Revised: 06/30/2017] [Accepted: 07/02/2017] [Indexed: 11/25/2022] Open
Abstract
Magnetic resonance imaging (MRI) of the human spinal cord at 7T has been demonstrated by a handful of research sites worldwide, and the spinal cord remains one of the areas in which higher fields and resolution could have high impact. The small diameter of the cord (∼1 cm) necessitates high spatial resolution to minimize partial volume effects between gray and white matter, and so MRI of the cord can greatly benefit from increased signal-to-noise ratio and contrasts at ultra-high field (UHF). Herein we review the current state of UHF spinal cord imaging. Technical challenges to successful UHF spinal cord MRI include radiofrequency (B1) nonuniformities and a general lack of optimized radiofrequency coils, amplified physiological noise, and an absence of methods for robust B0 shimming along the cord to mitigate image distortions and signal losses. Numerous solutions to address these challenges have been and are continuing to be explored, and include novel approaches for signal excitation and acquisition, dynamic shimming and specialized shim coils, and acquisitions with increased coverage or optimal slice angulations.
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Affiliation(s)
- Robert L Barry
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, MA, USA; Department of Radiology, Harvard Medical School, Boston, MA, USA.
| | - S Johanna Vannesjo
- Oxford Centre for Functional MRI of the Brain (FMRIB), Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - Samantha By
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, USA; Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, USA
| | - John C Gore
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, USA; Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, USA; Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Seth A Smith
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, USA; Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, USA; Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN, USA
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33
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Veldsman M. Brain Atrophy Estimated from Structural Magnetic Resonance Imaging as a Marker of Large-Scale Network-Based Neurodegeneration in Aging and Stroke. Geriatrics (Basel) 2017; 2:geriatrics2040034. [PMID: 31011044 PMCID: PMC6371114 DOI: 10.3390/geriatrics2040034] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Revised: 10/30/2017] [Accepted: 11/09/2017] [Indexed: 11/17/2022] Open
Abstract
Brain atrophy is a normal part of healthy aging, and stroke appears to have neurodegenerative effects, accelerating this atrophy to pathological levels. The distributed pattern of atrophy in healthy aging suggests that large-scale brain networks may be involved. At the same time, the network wide effects of stroke are beginning to be appreciated. There is now widespread use of network methods to understand the brain in terms of coordinated brain activity or white matter connectivity. Examining brain morphology on a network level presents a powerful method of understanding brain structure and has been successfully applied to charting the course of brain development. This review will introduce recent advances in structural magnetic resonance imaging (MRI) acquisition and analyses that have allowed for reliable and reproducible estimates of atrophy in large-scale brain networks in aging and after stroke. These methods are currently underutilized despite their ease of acquisition and potential to clarify the progression of brain atrophy as a normal part of healthy aging and in the context of stroke. Understanding brain atrophy at the network level may be key to clarifying healthy aging processes and the pathway to neurodegeneration after stroke.
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Affiliation(s)
- Michele Veldsman
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK.
- The Florey Institute for Neuroscience and Mental Health, University of Melbourne, Melbourne VIC 3084, Australia.
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34
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Tsukimura I, Murakami H, Sasaki M, Endo H, Yamabe D, Oikawa R, Doita M. Assessment of magnetic field interactions and radiofrequency-radiation-induced heating of metallic spinal implants in 7 T field. J Orthop Res 2017; 35:1831-1837. [PMID: 27769107 PMCID: PMC5573950 DOI: 10.1002/jor.23464] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/17/2016] [Accepted: 10/14/2016] [Indexed: 02/04/2023]
Abstract
The safety of metallic spinal implants in magnetic resonance imaging (MRI) performed using ultrahigh fields has not been established. Hence, we examined whether the displacement forces caused by a static magnetic field and the heating induced by radiofrequency radiation are substantial for spinal implants in a 7 T field. We investigated spinal rods of various lengths and materials, a screw, and a cross-linking bridge in accordance with the American Society for Testing and Materials guidelines. The displacement forces of the metallic implants in static 7 T and 3 T static magnetic fields were measured and compared. The temperature changes of the implants during 15-min-long fast spin-echo and balanced gradient-echo image acquisition sequences were measured in the 7 T field. The deflection angles of the metallic spinal materials in the 7 T field were 5.0-21.0° [median: 6.7°], significantly larger than those in the 3 T field (1.0-6.3° [2.2°]). Among the metallic rods, the cobalt-chrome rods had significantly larger deflection angles (17.8-21.0° [19.8°]) than the pure titanium and titanium alloy rods (5.0-7.7° [6.2°]). The temperature changes of the implants, including the cross-linked rods, were 0.7-1.0°C [0.8°C] and 0.6-1.0°C [0.7°C] during the fast spin-echo and balanced gradient-echo sequences, respectively; these changes were slightly larger than those of the controls (0.4-1.1°C [0.5°C] and 0.3-0.9°C [0.6°C], respectively). All of the metallic spinal implants exhibited small displacement forces and minimal heating, indicating that MRI examinations using 7 T fields may be performed safely on patients with these implants. © 2016 The Authors. Journal of Orthopaedic Research Published by Wiley Periodicals, Inc. on behalf of Orthopaedic Research Society. J Orthop Res 35:1831-1837, 2017.
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Affiliation(s)
- Itsuko Tsukimura
- Department of Orthopedic SurgerySchool of MedicineIwate Medical University19‐1 UchimaruMorioka020‐8505Japan
| | - Hideki Murakami
- Department of Orthopedic SurgerySchool of MedicineIwate Medical University19‐1 UchimaruMorioka020‐8505Japan
| | - Makoto Sasaki
- Division of Ultrahigh Field MRIInstitute of Biomedical SciencesIwate Medical UniversityMoriokaJapan
| | - Hirooki Endo
- Department of Orthopedic SurgerySchool of MedicineIwate Medical University19‐1 UchimaruMorioka020‐8505Japan
| | - Daisuke Yamabe
- Department of Orthopedic SurgerySchool of MedicineIwate Medical University19‐1 UchimaruMorioka020‐8505Japan
| | - Ryosuke Oikawa
- Department of Orthopedic SurgerySchool of MedicineIwate Medical University19‐1 UchimaruMorioka020‐8505Japan
| | - Minoru Doita
- Department of Orthopedic SurgerySchool of MedicineIwate Medical University19‐1 UchimaruMorioka020‐8505Japan
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35
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Magnetic Resonance Imaging Safety of Magnetically Controlled Growing Rods in an In Vivo Animal Model. Spine (Phila Pa 1976) 2017; 42:E504-E508. [PMID: 28441680 DOI: 10.1097/brs.0000000000001880] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN Experimental animal study. OBJECTIVE To investigate the interaction between magnetically controlled growing rods (MCGRs) and magnetic resonance imaging (MRI). SUMMARY OF BACKGROUND DATA Growing rod treatment through serial operations results in adverse effects on the patient and high treatment costs. MCGRs can be lengthened noninvasively in an outpatient setting and with lower treatment costs. When MRI investigation is required, the interaction between MCGRs and MRI is an issue of concern in patients with MCGRs. This study investigated MRI compatibility of MCGRs in an in vivo setting. METHODS The study was conducted on three sheep. A standard posterior approach was used. One polyaxial pedicle screw at the ends was placed. Two sheep were instrumented unilaterally and one bilaterally with MCGRs. Temperature change was measured using MR-compatible sensors. Thoracic and lumbar MRIs were obtained using a 0.3 T MRI unit. MRI waves were applied for 45 minutes and temperature changes were recorded every 3 minutes. The lengths of the MCGRs were measured and anteroposterior and lateral spine radiographs were obtained pre- and postoperatively. RESULTS No displacement in the positions of the MCGRs occurred. The lengths of the MCGRs did not change compared with the preoperative length. The ability of the MCGRs to elongate was not impaired after MRI scanning. There was a mean increase in the temperature of the MCGRs by 1.45°C (0.5-2.4°C). The MCGRs had a strong scattering effect on MRI of the related segments. CONCLUSION This study indicated that lower magnet MRI is safe in an animal model with MCGRs, with no displacement of the rods and no changes in their length, no significant heating, and no adverse effects on the lengthening mechanism but with a significant scattering effect on visualization of the surrounding tissues. Further investigations are needed to clarify the exact distance where an MRI investigation of distant organs may be done without scattering. LEVEL OF EVIDENCE N/A.
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36
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Jungmann PM, Agten CA, Pfirrmann CW, Sutter R. Advances in MRI around metal. J Magn Reson Imaging 2017; 46:972-991. [PMID: 28342291 DOI: 10.1002/jmri.25708] [Citation(s) in RCA: 126] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2016] [Accepted: 03/03/2017] [Indexed: 01/02/2023] Open
Abstract
The prevalence of orthopedic metal implants is continuously rising in the aging society. Particularly the number of joint replacements is increasing. Although satisfying long-term results are encountered, patients may suffer from complaints or complications during follow-up, and often undergo magnetic resonance imaging (MRI). Yet metal implants cause severe artifacts on MRI, resulting in signal-loss, signal-pileup, geometric distortion, and failure of fat suppression. In order to allow for adequate treatment decisions, metal artifact reduction sequences (MARS) are essential for proper radiological evaluation of postoperative findings in these patients. During recent years, developments of musculoskeletal imaging have addressed this particular technical challenge of postoperative MRI around metal. Besides implant material composition, configuration and location, selection of appropriate MRI hardware, sequences, and parameters influence artifact genesis and reduction. Application of dedicated metal artifact reduction techniques including high bandwidth optimization, view angle tilting (VAT), and the multispectral imaging techniques multiacquisition variable-resonance image combination (MAVRIC) and slice-encoding for metal artifact correction (SEMAC) may significantly reduce metal-induced artifacts, although at the expense of signal-to-noise ratio and/or acquisition time. Adding advanced image acquisition techniques such as parallel imaging, partial Fourier transformation, and advanced reconstruction techniques such as compressed sensing further improves MARS imaging in a clinically feasible scan time. This review focuses on current clinically applicable MARS techniques. Understanding of the main principles and techniques including their limitations allows a considerate application of these techniques in clinical practice. Essential orthopedic metal implants and postoperative MR findings around metal are presented and highlighted with clinical examples. LEVEL OF EVIDENCE 4 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2017;46:972-991.
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Affiliation(s)
- Pia M Jungmann
- Department of Radiology, Balgrist University Hospital, Zurich, Switzerland.,Faculty of Medicine, University of Zurich, Zurich, Switzerland.,Department of Radiology, Technical University of Munich, Munich, Germany
| | - Christoph A Agten
- Department of Radiology, Balgrist University Hospital, Zurich, Switzerland.,Faculty of Medicine, University of Zurich, Zurich, Switzerland
| | - Christian W Pfirrmann
- Department of Radiology, Balgrist University Hospital, Zurich, Switzerland.,Department of Radiology, Technical University of Munich, Munich, Germany
| | - Reto Sutter
- Department of Radiology, Balgrist University Hospital, Zurich, Switzerland.,Department of Radiology, Technical University of Munich, Munich, Germany
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Noureddine Y, Kraff O, Ladd ME, Wrede KH, Chen B, Quick HH, Schaefers G, Bitz AK. In vitro and in silico assessment of RF-induced heating around intracranial aneurysm clips at 7 Tesla. Magn Reson Med 2017; 79:568-581. [DOI: 10.1002/mrm.26650] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Revised: 01/11/2017] [Accepted: 01/26/2017] [Indexed: 11/12/2022]
Affiliation(s)
- Yacine Noureddine
- Erwin L. Hahn Institute for Magnetic Resonance Imaging; University Duisburg-Essen; Essen Germany
- MR:comp GmbH, MR Safety Testing Laboratory; Gelsenkirchen Germany
| | - Oliver Kraff
- Erwin L. Hahn Institute for Magnetic Resonance Imaging; University Duisburg-Essen; Essen Germany
| | - Mark E. Ladd
- Erwin L. Hahn Institute for Magnetic Resonance Imaging; University Duisburg-Essen; Essen Germany
- Division of Medical Physics in Radiology (E020); German Cancer Research Center (DKFZ); Heidelberg Germany
| | - Karsten H. Wrede
- Erwin L. Hahn Institute for Magnetic Resonance Imaging; University Duisburg-Essen; Essen Germany
- Department of Neurosurgery; University Hospital Essen; Essen Germany
| | - Bixia Chen
- Erwin L. Hahn Institute for Magnetic Resonance Imaging; University Duisburg-Essen; Essen Germany
- Department of Neurosurgery; University Hospital Essen; Essen Germany
| | - Harald H. Quick
- Erwin L. Hahn Institute for Magnetic Resonance Imaging; University Duisburg-Essen; Essen Germany
- High Field and Hybrid MR Imaging; University Hospital Essen; Essen Germany
| | - Gregor Schaefers
- MR:comp GmbH, MR Safety Testing Laboratory; Gelsenkirchen Germany
- MRI-STaR-Magnetic Resonance Institute for Safety, Technology and Research GmbH; Gelsenkirchen Germany
| | - Andreas K. Bitz
- Erwin L. Hahn Institute for Magnetic Resonance Imaging; University Duisburg-Essen; Essen Germany
- Division of Medical Physics in Radiology (E020); German Cancer Research Center (DKFZ); Heidelberg Germany
- Faculty of Electrical Engineering and Information Technology; FH Aachen-University of Applied Sciences; Aachen NRW Germany
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Abstract
This chapter is intended as a primer to the most widely used neuroimaging methods available in the prediction, diagnosis and monitoring of the neurodegenerative diseases. We describe the imaging methods that allow us to examine brain structure, function and pathology and investigate neurodegenerative mechanisms in vivo. We describe methods to interrogate brain structure with magnetic resonance imaging (MRI), and brain function with molecular imaging, functional MRI and electro- and magneto-encephalography. We highlight the major neuroimaging advances, including brain stimulation and connectomics, which have brought new insights into a wide range of neurodegenerative diseases and describe some of the challenges in imaging clinical populations. Finally, we discuss the future of neuroimaging in neurodegenerative disease and its potential for generating predictive, diagnostic and prognostic biomarkers.
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Affiliation(s)
- Michele Veldsman
- Nuffield Department of Clinical Neuroscience, University of Oxford, Level 6, West Wing, John Radcliffe Hospital, Oxford, OX3 9DU, UK.
- The Florey Institute of Neuroscience and Mental Health, Melbourne Brain Centre, 245 Burgundy Street, Heidelberg, VIC, 3084, Australia.
| | - Natalia Egorova
- The Florey Institute of Neuroscience and Mental Health, Melbourne Brain Centre, 245 Burgundy Street, Heidelberg, VIC, 3084, Australia
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Illanes A, Krug J, Abadi H, Friebe M. Distortion indicator algorithm for simple artifact assessment of passive MRI markers. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2016; 2016:1248-1251. [PMID: 28268551 DOI: 10.1109/embc.2016.7590932] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The main purpose of this work is to present a simple quantitative approach for assessing artifacts in passive instruments when used in an MRI environment. It is mainly based on a quantitative indicator related with the amount of distortion produced by the instrument on a 3D surface obtained from the 2D MR image. After a preprocessing stage for attenuation of the 3D surface low frequency components, an indicator related with the volume of the background distortion is computed for each MRI slice. Then a monotonically decreasing curve is calculated for assessing artifact level using all the slices of a sequence. Results show that an indicator can be computed automatically from all the slices of a given MRI sequence and through this indicator it is possible to perform comparative studies between artifacts produced by different catheters and needles.
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Romeo S, Sannino A, Scarfì MR, Massa R, d’Angelo R, Zeni O. Lack of effects on key cellular parameters of MRC-5 human lung fibroblasts exposed to 370 mT static magnetic field. Sci Rep 2016; 6:19398. [PMID: 26762783 PMCID: PMC4725921 DOI: 10.1038/srep19398] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Accepted: 12/07/2015] [Indexed: 01/22/2023] Open
Abstract
The last decades have seen increased interest toward possible adverse effects arising from exposure to intense static magnetic fields. This concern is mainly due to the wider and wider applications of such fields in industry and clinical practice; among them, Magnetic Resonance Imaging (MRI) facilities are the main sources of exposure to static magnetic fields for both general public (patients) and workers. In recent investigations, exposures to static magnetic fields have been demonstrated to elicit, in different cell models, both permanent and transient modifications in cellular endpoints critical for the carcinogenesis process. The World Health Organization has therefore recommended in vitro investigations as important research need, to be carried out under strictly controlled exposure conditions. Here we report on the absence of effects on cell viability, reactive oxygen species levels and DNA integrity in MRC-5 human foetal lung fibroblasts exposed to 370 mT magnetic induction level, under different exposure regimens. Exposures have been performed by using an experimental apparatus designed and realized for operating with the static magnetic field generated by permanent magnets, and confined in a magnetic circuit, to allow cell cultures exposure in absence of confounding factors like heating or electric field components.
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Affiliation(s)
- Stefania Romeo
- CNR – Institute for Electromagnetic Sensing of Environment, Via Diocleziano 328, 80124 Naples, Italy
| | - Anna Sannino
- CNR – Institute for Electromagnetic Sensing of Environment, Via Diocleziano 328, 80124 Naples, Italy
| | - Maria Rosaria Scarfì
- CNR – Institute for Electromagnetic Sensing of Environment, Via Diocleziano 328, 80124 Naples, Italy
| | - Rita Massa
- CNR – Institute for Electromagnetic Sensing of Environment, Via Diocleziano 328, 80124 Naples, Italy
- Department of Physics, University of Naples Federico II, CMSA via Cintia, 80126, Napoli, Italy
| | - Raffaele d’Angelo
- Italian Workers’ Compensation Authority (INAIL)–Regional Technical Advisory Department Risk and Prevention Assessment (CONTARP) of Campania, via Nuova Poggioreale, 80143 Napoli
| | - Olga Zeni
- CNR – Institute for Electromagnetic Sensing of Environment, Via Diocleziano 328, 80124 Naples, Italy
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41
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ORISO K, KOBAYASHI T, SASAKI M, UWANO I, KIHARA H, KONDO H. Impact of the Static and Radiofrequency Magnetic Fields Produced by a 7T MR Imager on Metallic Dental Materials. Magn Reson Med Sci 2016; 15:26-33. [DOI: 10.2463/mrms.2014-0122] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Affiliation(s)
- Kenta ORISO
- Department of Prosthodontics and Oral Implantology, Iwate Medical University
| | - Takuya KOBAYASHI
- Department of Prosthodontics and Oral Implantology, Iwate Medical University
| | - Makoto SASAKI
- Division of Ultrahigh Field MRI, Institute of Biomedical Sciences, Iwate Medical University
| | - Ikuko UWANO
- Division of Ultrahigh Field MRI, Institute of Biomedical Sciences, Iwate Medical University
| | - Hidemichi KIHARA
- Department of Prosthodontics and Oral Implantology, Iwate Medical University
| | - Hisatomo KONDO
- Department of Prosthodontics and Oral Implantology, Iwate Medical University
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Feng DX, McCauley JP, Morgan–Curtis FK, Salam RA, Pennell DR, Loveless ME, Dula AN. Evaluation of 39 medical implants at 7.0 T. Br J Radiol 2015; 88:20150633. [PMID: 26481696 PMCID: PMC4984944 DOI: 10.1259/bjr.20150633] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Revised: 10/06/2015] [Accepted: 10/19/2015] [Indexed: 11/05/2022] Open
Abstract
OBJECTIVE With increased signal to noise ratios, 7.0-T MRI has the potential to contribute unique information regarding anatomy and pathophysiology of a disease. However, concerns for the safety of subjects with metallic medical implants have hindered advancement in this field. The purpose of the present research was to evaluate the MRI safety for 39 commonly used medical implants at 7.0 T. METHODS Selected metallic implants were tested for magnetic field interactions, radiofrequency-induced heating and artefacts using standardized testing techniques. RESULTS 5 of the 39 implants tested may be unsafe for subjects undergoing MRI at 7.0 T. CONCLUSION Implants were deemed either "MR Conditional" or "MR Unsafe" for the 7.0-T MRI environment. Further research is needed to expand the existing database categorizing implants that are acceptable for patients referred for MRI examinations at 7.0 T. ADVANCES IN KNOWLEDGE Lack of MRI testing for common metallic medical implants limits the translational potential of 7.0-T MRI. For safety reasons, patients with metallic implants are not allowed to undergo a 7.0-T MRI scan, precluding part of the population that can benefit from the detailed resolution of ultra-high-field MRIs. This investigation provides necessary MRI testing of common medical implants at 7.0 T.
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Affiliation(s)
- David X Feng
- School for Science and Math at Vanderbilt University, Vanderbilt University, Nashville, TN, USA
| | - Joseph P McCauley
- School for Science and Math at Vanderbilt University, Vanderbilt University, Nashville, TN, USA
| | - Fea K Morgan–Curtis
- School for Science and Math at Vanderbilt University, Vanderbilt University, Nashville, TN, USA
| | - Redoan A Salam
- School for Science and Math at Vanderbilt University, Vanderbilt University, Nashville, TN, USA
| | - David R Pennell
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Mary E Loveless
- School for Science and Math at Vanderbilt University, Vanderbilt University, Nashville, TN, USA
| | - Adrienne N Dula
- Vanderbilt University Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, USA
- Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, TN, USA
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Benjamin P, Viessmann O, MacKinnon AD, Jezzard P, Markus HS. 7 Tesla MRI in Cerebral Small Vessel Disease. Int J Stroke 2015; 10:659-64. [PMID: 25845965 DOI: 10.1111/ijs.12490] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2014] [Accepted: 02/04/2015] [Indexed: 11/29/2022]
Abstract
Cerebral small vessel disease (SVD) is a major cause of stroke and cognitive decline. Magnetic resonance imaging (MRI) currently plays a central role in diagnosis, and advanced MRI techniques are widely used in research but are limited by spatial resolution. Human 7 Tesla (7T) MRI has recently become available offering the ability to image at higher spatial resolution. This may provide additional insights into both the vascular pathology itself as well as parenchymal markers which could only previously be examined post mortem. In this review we cover the advantages and limitations of 7T MRI, review studies in SVD performed to date, and discuss potential future insights into SVD which 7T MRI may provide.
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Affiliation(s)
- Philip Benjamin
- Neurosciences Research Centre, St George's University of London, London, UK
| | - Olivia Viessmann
- Functional MRI of the Brain (FMRIB) Centre, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - Andrew D. MacKinnon
- Atkinson Morley Regional Neuroscience Centre, St George's NHS Healthcare Trust, London, UK
| | - Peter Jezzard
- Functional MRI of the Brain (FMRIB) Centre, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - Hugh S. Markus
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
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Winter L, Oberacker E, Özerdem C, Ji Y, von Knobelsdorff-Brenkenhoff F, Weidemann G, Ittermann B, Seifert F, Niendorf T. On the RF heating of coronary stents at 7.0 Tesla MRI. Magn Reson Med 2014; 74:999-1010. [PMID: 25293952 DOI: 10.1002/mrm.25483] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2014] [Revised: 09/11/2014] [Accepted: 09/11/2014] [Indexed: 12/16/2022]
Abstract
PURPOSE Examine radiofrequency (RF) induced heating of coronary stents at 7.0 Tesla (T) to derive an analytical approach which supports RF heating assessment of arbitrary stent geometries and RF coils. METHODS Simulations are performed to detail electromagnetic fields (EMF), local specific absorption rates (SAR) and temperature changes. For validation E-field measurements and RF heating experiments are conducted. To progress to clinical setups RF coils tailored for cardiac MRI at 7.0T and coronary stents are incorporated into EMF simulations using a human voxel model. RESULTS Our simulations of coronary stents at 297 MHz were confirmed by E-field and temperature measurements. An analytical solution which describes SAR(1g tissue voxel) induced by an arbitrary coronary stent interfering with E-fields generated by an arbitrary RF coil was derived. The analytical approach yielded a conservative estimation of induced SAR(1g tissue voxel) maxima without the need for integrating the stent into EMF simulations of the human voxel model. CONCLUSION The proposed analytical approach can be applied for any patient, coronary stent type, RF coil configuration and RF transmission regime. The generalized approach is of value for RF heating assessment of other passive electrically conductive implants and provides a novel design criterion for RF coils.
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Affiliation(s)
- Lukas Winter
- Berlin Ultrahigh Field Facility (B.U.F.F.), Max-Delbrueck Center for Molecular Medicine, Berlin, Germany
| | - Eva Oberacker
- Berlin Ultrahigh Field Facility (B.U.F.F.), Max-Delbrueck Center for Molecular Medicine, Berlin, Germany
| | - Celal Özerdem
- Berlin Ultrahigh Field Facility (B.U.F.F.), Max-Delbrueck Center for Molecular Medicine, Berlin, Germany
| | - Yiyi Ji
- Berlin Ultrahigh Field Facility (B.U.F.F.), Max-Delbrueck Center for Molecular Medicine, Berlin, Germany
| | - Florian von Knobelsdorff-Brenkenhoff
- Berlin Ultrahigh Field Facility (B.U.F.F.), Max-Delbrueck Center for Molecular Medicine, Berlin, Germany.,Experimental and Clinical Research Center (ECRC), a joint cooperation between the Charité Medical Faculty and the Max-Delbrueck Center for Molecular Medicine, Berlin, Germany
| | - Gerd Weidemann
- Physikalisch Technische Bundesanstalt (PTB), Braunschweig and Berlin, Germany
| | - Bernd Ittermann
- Physikalisch Technische Bundesanstalt (PTB), Braunschweig and Berlin, Germany
| | - Frank Seifert
- Physikalisch Technische Bundesanstalt (PTB), Braunschweig and Berlin, Germany
| | - Thoralf Niendorf
- Berlin Ultrahigh Field Facility (B.U.F.F.), Max-Delbrueck Center for Molecular Medicine, Berlin, Germany.,Experimental and Clinical Research Center (ECRC), a joint cooperation between the Charité Medical Faculty and the Max-Delbrueck Center for Molecular Medicine, Berlin, Germany
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