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Guimarães J, de Almeida J, Mendes PL, Ferreira MJ, Gonçalves L. Advancements in non-invasive imaging of atherosclerosis: Future perspectives. J Clin Lipidol 2024; 18:e142-e152. [PMID: 38142178 DOI: 10.1016/j.jacl.2023.11.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2023] [Revised: 11/11/2023] [Accepted: 11/14/2023] [Indexed: 12/25/2023]
Abstract
Atherosclerosis is a chronic inflammatory disease characterized by the buildup of plaques in arterial walls, leading to cardiovascular diseases and high morbidity and mortality rates worldwide. Non-invasive imaging techniques play a crucial role in evaluating patients with suspected or established atherosclerosis. However, there is a growing body of evidence suggesting the need to visualize the underlying processes of plaque progression and rupture to enhance risk stratification. This review explores recent advancements in non-invasive assessment of atherosclerosis, focusing on computed tomography, magnetic resonance imaging, and nuclear imaging. These advancements provide valuable insights into the assessment and management of atherosclerosis, potentially leading to better risk stratification and improved patient outcomes.
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Affiliation(s)
- Joana Guimarães
- Cardiology Department, Coimbra's Hospital and University Center, Praceta Mota Pinto, 3000-561 Coimbra, Portugal.
| | - José de Almeida
- Cardiology Department, Coimbra's Hospital and University Center, Praceta Mota Pinto, 3000-561 Coimbra, Portugal
| | - Paulo Lázaro Mendes
- Cardiology Department, Coimbra's Hospital and University Center, Praceta Mota Pinto, 3000-561 Coimbra, Portugal
| | - Maria João Ferreira
- Cardiology Department, Coimbra's Hospital and University Center, Praceta Mota Pinto, 3000-561 Coimbra, Portugal; Faculty of Medicine, Coimbra's University, Azinhaga de Santa Comba, 3000-548 Coimbra, Portugal
| | - Lino Gonçalves
- Cardiology Department, Coimbra's Hospital and University Center, Praceta Mota Pinto, 3000-561 Coimbra, Portugal; Faculty of Medicine, Coimbra's University, Azinhaga de Santa Comba, 3000-548 Coimbra, Portugal
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2
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Rios NL, Gilbert KM, Papp D, Cereza G, Foias A, Rangaprakash D, May MW, Guerin B, Wald LL, Keil B, Stockmann JP, Barry RL, Cohen-Adad J. An 8-channel Tx dipole and 20-channel Rx loop coil array for MRI of the cervical spinal cord at 7 Tesla. NMR IN BIOMEDICINE 2023; 36:e5002. [PMID: 37439129 PMCID: PMC10733907 DOI: 10.1002/nbm.5002] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Revised: 05/10/2023] [Accepted: 06/15/2023] [Indexed: 07/14/2023]
Abstract
The quality of cervical spinal cord images can be improved by the use of tailored radiofrequency (RF) coil solutions for ultrahigh field imaging; however, very few commercial and research 7-T RF coils currently exist for the spinal cord, and in particular, those with parallel transmission (pTx) capabilities. This work presents the design, testing, and validation of a pTx/Rx coil for the human neck and cervical/upper thoracic spinal cord. The pTx portion is composed of eight dipoles to ensure high homogeneity over this large region of the spinal cord. The Rx portion is made up of twenty semiadaptable overlapping loops to produce high signal-to-noise ratio (SNR) across the patient population. The coil housing is designed to facilitate patient positioning and comfort, while also being tight fitting to ensure high sensitivity. We demonstrate RF shimming capabilities to optimize B1 + uniformity, power efficiency, and/or specific absorption rate efficiency. B1 + homogeneity, SNR, and g-factor were evaluated in adult volunteers and demonstrated excellent performance from the occipital lobe down to the T4-T5 level. We compared the proposed coil with two state-of-the-art head and head/neck coils, confirming its superiority in the cervical and upper thoracic regions of the spinal cord. This coil solution therefore provides a convincing platform for producing the high image quality necessary for clinical and research scanning of the upper spinal cord.
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Affiliation(s)
- Nibardo Lopez Rios
- NeuroPoly Lab, Institute of Biomedical Engineering, Polytechnique Montréal, Montréal, QC, Canada
| | - Kyle M. Gilbert
- Centre for Functional and Metabolic Mapping, The University of Western Ontario, London, ON, Canada
| | - Daniel Papp
- NeuroPoly Lab, Institute of Biomedical Engineering, Polytechnique Montréal, Montréal, QC, Canada
| | - Gaspard Cereza
- NeuroPoly Lab, Institute of Biomedical Engineering, Polytechnique Montréal, Montréal, QC, Canada
| | - Alexandru Foias
- NeuroPoly Lab, Institute of Biomedical Engineering, Polytechnique Montréal, Montréal, QC, Canada
| | - D. Rangaprakash
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, MA, USA
- Harvard Medical School, Boston, MA, USA
| | - Markus W. May
- Erwin L. Hahn Institute for Magnetic Resonance Imaging, University of Duisburg-Essen, Essen, Germany
- High Field and Hybrid MR Imaging, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
| | - Bastien Guerin
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, MA, USA
- Harvard Medical School, Boston, MA, USA
| | - Lawrence L. Wald
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, MA, USA
- Harvard Medical School, Boston, MA, USA
- Harvard-Massachusetts Institute of Technology Health Sciences & Technology, Cambridge, MA, USA
| | - Boris Keil
- Institute of Medical Physics and Radiation Protection, University of Applied Sciences Mittelhessen, Giessen, Germany
- Department of Diagnostic and Interventional Radiology, University Hospital Marburg, Philipps University of Marburg, Marburg, Germany
| | - Jason P. Stockmann
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, MA, USA
- Harvard Medical School, Boston, MA, USA
| | - Robert L. Barry
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, MA, USA
- Harvard Medical School, Boston, MA, USA
- Harvard-Massachusetts Institute of Technology Health Sciences & Technology, Cambridge, MA, USA
| | - Julien Cohen-Adad
- NeuroPoly Lab, Institute of Biomedical Engineering, Polytechnique Montréal, Montréal, QC, Canada
- Functional Neuroimaging Unit, CRIUGM, Université de Montréal, Montreal, QC, Canada
- Mila – Quebec AI Institute, Montreal, QC, Canada
- Centre de recherche du CHU Sainte-Justine, Université de Montréal, Montréal, QC, Canada
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3
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Rios NL, Gilbert KM, Papp D, Cereza G, Foias A, Rangaprakash D, May MW, Guerin B, Wald LL, Keil B, Stockmann JP, Barry RL, Cohen-Adad J. 8-channel Tx dipole and 20-channel Rx loop coil array for MRI of the cervical spinal cord at 7 Tesla. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.08.527664. [PMID: 36798276 PMCID: PMC9934596 DOI: 10.1101/2023.02.08.527664] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
The quality of cervical spinal cord images can be improved by the use of tailored radiofrequency coil solutions for ultra-high field imaging; however, very few commercial and research 7 Tesla radiofrequency coils currently exist for the spinal cord, and in particular those with parallel transmit capabilities. This work presents the design, testing and validation of a pTx/Rx coil for the human neck and cervical/upper-thoracic spinal cord. The pTx portion is composed of 8 dipoles to ensure high homogeneity over this large region of the spinal cord. The Rx portion is made of 20 semi-adaptable overlapping loops to produce high Signal-to-noise ratio (SNR) across the patient population. The coil housing is designed to facilitate patient positioning and comfort, while being tight fitting to ensure high sensitivity. We demonstrate RF shimming capabilities to optimize B 1 + uniformity, power efficiency and/or specific absorption rate (SAR) efficiency. B 1 + homogeneity, SNR and g-factor was evaluated in adult volunteers and demonstrated excellent performance from the occipital lobe down to the T4-T5 level. We compared the proposed coil with two state-of-the-art head and head/neck coils, confirming its superiority in the cervical and upper-thoracic regions of the spinal cord. This coil solution therefore provides a convincing platform for producing the high image quality necessary for clinical and research scanning of the upper spinal cord.
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Affiliation(s)
- Nibardo Lopez Rios
- NeuroPoly Lab, Institute of Biomedical Engineering, Polytechnique Montréal, Montreal, QC, Canada
| | - Kyle M. Gilbert
- Centre for Functional and Metabolic Mapping, The University of Western Ontario, London, ON, Canada
| | - Daniel Papp
- NeuroPoly Lab, Institute of Biomedical Engineering, Polytechnique Montréal, Montreal, QC, Canada
| | - Gaspard Cereza
- NeuroPoly Lab, Institute of Biomedical Engineering, Polytechnique Montréal, Montreal, QC, Canada
| | - Alexandru Foias
- NeuroPoly Lab, Institute of Biomedical Engineering, Polytechnique Montréal, Montreal, QC, Canada
| | - D. Rangaprakash
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, MA, USA
- Harvard Medical School, Boston, MA, USA
| | - Markus W. May
- Erwin L. Hahn Institute for Magnetic Resonance Imaging, University of Duisburg-Essen, Essen, Germany
- High Field and Hybrid MR Imaging, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
| | - Bastien Guerin
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, MA, USA
- Harvard Medical School, Boston, MA, USA
| | - Lawrence L. Wald
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, MA, USA
- Harvard Medical School, Boston, MA, USA
- Harvard-Massachusetts Institute of Technology Health Sciences & Technology, Cambridge, MA, USA
| | - Boris Keil
- Institute of Medical Physics and Radiation Protection, University of Applied Sciences Mittelhessen, Giessen, Germany
- Department of Diagnostic and Interventional Radiology, University Hospital Marburg, Philipps University of Marburg, Marburg, Germany
| | - Jason P. Stockmann
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, MA, USA
- Harvard Medical School, Boston, MA, USA
| | - Robert L. Barry
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, MA, USA
- Harvard Medical School, Boston, MA, USA
- Harvard-Massachusetts Institute of Technology Health Sciences & Technology, Cambridge, MA, USA
| | - Julien Cohen-Adad
- NeuroPoly Lab, Institute of Biomedical Engineering, Polytechnique Montréal, Montreal, QC, Canada
- Functional Neuroimaging Unit, CRIUGM, Université de Montréal, Montreal, QC, Canada
- Mila – Quebec AI Institute, Montreal, QC, Canada
- Centre de recherche du CHU Sainte-Justine, Université de Montréal, Montréal, QC, Canada
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Carotid Artery Plaque Identification and Display System (MRI-CAPIDS) Using Opensource Tools. Diagnostics (Basel) 2020; 10:diagnostics10121111. [PMID: 33371362 PMCID: PMC7767364 DOI: 10.3390/diagnostics10121111] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Revised: 12/07/2020] [Accepted: 12/15/2020] [Indexed: 11/21/2022] Open
Abstract
Magnetic resonance imaging (MRI) represents one modality in atherosclerosis risk assessment, by permitting the classification of carotid plaques into either high- or low-risk lesions. Although MRI is generally used for observing the impact of atherosclerosis on vessel lumens, it can also show both the size and composition of itself, as well as plaque information, thereby providing information beyond that of simple stenosis. Software systems are a valuable aid in carotid artery stenosis assessment wherein commercial software is readily available but is not accessible to all practitioners because of its often high cost. This study focuses on the development of a software system designed entirely for registration, marking, and 3D visualization of the wall and lumen, using freely available open-source tools and libraries. It was designed to be free from “feature bloat” and avoid “feature-creep.” The image loading and display module of the modified QDCM library was improved by a minimum of 10,000%. A Bezier function was used in order to smoothen the curve of the polygon (referring to the shape formed by the marked points) by interpolating additional points between the marked points. This smoother curve led to a smoother 3D view of the lumen and wall.
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5
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Schmitter S, Adriany G, Waks M, Moeller S, Aristova M, Vali A, Auerbach EJ, Van de Moortele PF, Ugurbil K, Schnell S. Bilateral Multiband 4D Flow MRI of the Carotid Arteries at 7T. Magn Reson Med 2020; 84:1947-1960. [PMID: 32187742 DOI: 10.1002/mrm.28256] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Revised: 01/31/2020] [Accepted: 02/24/2020] [Indexed: 12/26/2022]
Abstract
PURPOSE Simultaneous multislab (SMSb) 4D flow MRI was developed and implemented at 7T for accelerated acquisition of the 3D blood velocity vector field in both carotid bifurcations. METHODS SMSb was applied to 4D flow to acquire blood velocities in both carotid bifurcations in sagittal orientation using a local transmit/receive coil at 7T. B 1 + transmit efficiency was optimized by B 1 + shimming. SMSb 4D flow was obtained in 8 healthy subjects in single-band (SB) and multiband (MB) fashion. Additionally, MB data were retrospectively undersampled to simulate GRAPPA R = 2 (MB2_GRAPPA2), and both SB datasets were added to form an artificial MB dataset (SumSB). The band separation performance was quantified by signal leakage. Peak velocity and total flow values were calculated and compared to SB via intraclass correlation analysis (ICC). RESULTS Clean slab separation was achieved yielding a mean signal leakage of 13% above the mean SB noise level. Mean total flow for MB2, SumSB, and MB_GRAPPA2 deviated less than 9% from the SB values. Peak velocities averaged over all vessels and subjects were 0.48 ± 0.11 m/s for SB, 0.47 ± 0.12 m/s for SumSB, 0.50 ± 0.13 m/s for MB2, and 0.53 ± 0.13 m/s for MB2_GRAPPA2. ICC revealed excellent absolute agreement and consistency of total flow for all methods compared to SB2. Peak velocity showed good to excellent agreement and consistency for SumSB and MB2 and MB2_GRAPPA2 method showed poor to excellent agreement and good to excellent consistency. CONCLUSION Simultaneous multislab 4D Flow MRI allows accurate quantification of total flow and peak velocity while reducing scan times.
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Affiliation(s)
- Sebastian Schmitter
- Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, USA.,Physikalisch-Technische Bundesanstalt, Braunschweig and Berlin, Germany
| | - Gregor Adriany
- Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, USA
| | - Matt Waks
- Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, USA
| | - Steen Moeller
- Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, USA
| | - Maria Aristova
- McCormick School of Engineering, Northwestern University, Evanston, USA.,Feinberg School of Medicine, Northwestern University, Chicago, USA
| | - Alireza Vali
- Feinberg School of Medicine, Northwestern University, Chicago, USA
| | - Edward J Auerbach
- Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, USA
| | | | - Kamil Ugurbil
- Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, USA
| | - Susanne Schnell
- Feinberg School of Medicine, Northwestern University, Chicago, USA
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Wüst RCI, Calcagno C, Daal MRR, Nederveen AJ, Coolen BF, Strijkers GJ. Emerging Magnetic Resonance Imaging Techniques for Atherosclerosis Imaging. Arterioscler Thromb Vasc Biol 2020; 39:841-849. [PMID: 30917678 DOI: 10.1161/atvbaha.118.311756] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Atherosclerosis is a prevalent disease affecting a large portion of the population at one point in their lives. There is an unmet need for noninvasive diagnostics to identify and characterize at-risk plaque phenotypes noninvasively and in vivo, to improve the stratification of patients with cardiovascular disease, and for treatment evaluation. Magnetic resonance imaging is uniquely positioned to address these diagnostic needs. However, currently available magnetic resonance imaging methods for vessel wall imaging lack sufficient discriminative and predictive power to guide the individual patient needs. To address this challenge, physicists are pushing the boundaries of magnetic resonance atherosclerosis imaging to increase image resolution, provide improved quantitative evaluation of plaque constituents, and obtain readouts of disease activity such as inflammation. Here, we review some of these important developments, with specific focus on emerging applications using high-field magnetic resonance imaging, the use of quantitative relaxation parameter mapping for improved plaque characterization, and novel 19F magnetic resonance imaging technology to image plaque inflammation.
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Affiliation(s)
- Rob C I Wüst
- From the Biomedical Engineering and Physics (R.C.I.W., M.R.R.D., B.F.C., G.J.S.), Amsterdam Cardiovascular Sciences, Amsterdam UMC, University of Amsterdam, the Netherlands
| | - Claudia Calcagno
- Department of Radiology, Translational and Molecular Imaging Institute, Icahn School of Medicine at Mount Sinai, New York (C.C., G.J.S.)
| | - Mariah R R Daal
- From the Biomedical Engineering and Physics (R.C.I.W., M.R.R.D., B.F.C., G.J.S.), Amsterdam Cardiovascular Sciences, Amsterdam UMC, University of Amsterdam, the Netherlands
| | - Aart J Nederveen
- Radiology and Nuclear Medicine (A.J.N.), Amsterdam Cardiovascular Sciences, Amsterdam UMC, University of Amsterdam, the Netherlands
| | - Bram F Coolen
- From the Biomedical Engineering and Physics (R.C.I.W., M.R.R.D., B.F.C., G.J.S.), Amsterdam Cardiovascular Sciences, Amsterdam UMC, University of Amsterdam, the Netherlands
| | - Gustav J Strijkers
- From the Biomedical Engineering and Physics (R.C.I.W., M.R.R.D., B.F.C., G.J.S.), Amsterdam Cardiovascular Sciences, Amsterdam UMC, University of Amsterdam, the Netherlands.,Department of Radiology, Translational and Molecular Imaging Institute, Icahn School of Medicine at Mount Sinai, New York (C.C., G.J.S.)
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Abstract
Background The quality of carotid wall MRI can benefit substantially from a dedicated RF coil that is tailored towards the human neck geometry and optimized for image signal-to-noise ratio (SNR), parallel imaging performance and RF penetration depth and coverage. In last decades, several of such dedicated carotid coils were introduced. However, a comparison of the more successful designs is still lacking. Objective To perform a head-to-head comparison over four dedicated MR carotid surface coils with 4, 6, 8 and 30 coil elements, respectively. Material and methods Ten volunteers were scanned on a 3T scanner. For each subject, multiple black-blood carotid vessel wall images were measured using the four coils with different parallel imaging settings. The performance of the coils was evaluated and compared in terms of image coverage, penetration depth and noise correlations between elements. Vessel wall of a common carotid section was delineated manually. Subsequently, images were assessed based on vessel wall morphology and image quality parameters. The morphological parameters consisted of the vessel wall area, thickness, and normalized wall index (wall area/total vessel area). Image quality parameters consisted of vessel wall SNR, wall-lumen contrast-to-noise ratio (CNR), the vessel g-factor, and CNRindex ((wall–lumen signal) / (wall+lumen signal)). Repeated measures analysis of variance (rmANOVA) was applied for each parameter for the averaged 10 slices for all volunteers to assess effect of coil and SENSE factor. If the rmANOVA was significant, post-hoc comparisons were conducted. Results No significant coil effect were found for vessel wall morphological parameters. SENSE acceleration affected some morphological parameters for 6- and 8-channel coils, but had no effect on the 30-channel coil. The 30-channel coil achieved high acceleration factors (10x) with significantly lower vessel g-factor values (ps ≤ 0.01), but lower vessel wall SNR and CNR values (ps ≤ 0.01). Conclusion All four coils were capable of high-quality carotid MRI. The 30-channel coil is recommended when rapid image acquisition acceleration is required for 3D measurements, whereas 6- and 8-channel coils demonstrated the highest SNR performance.
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van Egmond SL, Vonck BM, Bluemink JJ, Pameijer FA, Dankbaar JW, Stegeman I, Philippens ME, van den Berg CA, Janssen LM, Terhaard CH. Clinical value of (dedicated) 3 Tesla and 7 Tesla MRI for cT1 glottic carcinoma: A feasibility study. Laryngoscope Investig Otolaryngol 2019; 4:95-101. [PMID: 30828625 PMCID: PMC6383319 DOI: 10.1002/lio2.246] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 10/26/2018] [Accepted: 12/10/2018] [Indexed: 11/10/2022] Open
Abstract
OBJECTIVE To assess the feasibility of the clinical use of 3 Tesla and 7 Tesla Magnetic Resonance Imaging for early (cT1) glottic carcinoma, including structural assessment of technical image quality and visibility of the tumor; and if feasible, to correlate MRI findings to routine diagnostics. METHODS Prospective feasibility study. Twenty patients with primary clinical T1 glottic carcinoma underwent both routine clinical staging and CT. In addition, a 3 T and 7 T MRI protocol, developed for small laryngeal lesions, was performed in a 4-point immobilization mask, using dedicated surface coils. Afterwards, routine endoscopic direct suspension laryngoscopy under general anaesthesia was performed. RESULTS Only 2 of 7 (29%) of 7 T MRI scans were rated as moderate to good technical image quality. After exclusion of three patients with only mild to moderate dysplasia at the time of MRI, 13 of 17 (76%) of 3 T MRIs were of adequate technical image quality. Tumor visualization was adequate in 8 of 13 (62%) of patients with invasive squamous cell carcinomas. With exclusion of the four MRIs with motion artefacts, the tumor and its boundaries could be adequately seen in 8 of 9 (89%) patients with squamous cell carcinoma versus only one in four (25%) of patients with carcinoma in situ lesions. CONCLUSIONS 7 Tesla MRI was considered not feasible. 3 Tesla MRI, with adequate patient selection, namely clinical exclusion of patients with a history of claustrophobia and inclusion of only histologically proven invasive squamous cell carcinoma, can be feasible. Especially with further improvement of MR image quality. LEVEL OF EVIDENCE 2B, prospective diagnostic study.
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Affiliation(s)
- Sylvia L. van Egmond
- Department of Otorhinolaryngology and Head & Neck SurgeryLeiden University Medical CenterLeidenThe Netherlands
- Department of Otorhinolaryngology and Head & Neck SurgeryUniversity Medical Center UtrechtUtrechtThe Netherlands
| | - Bernard M.D. Vonck
- Department of Otorhinolaryngology and Head & Neck SurgeryUniversity Medical Center UtrechtUtrechtThe Netherlands
| | - Johanna J. Bluemink
- Department of RadiotherapyUniversity Medical Center UtrechtUtrechtThe Netherlands
| | - Frank A. Pameijer
- Department of RadiologyUniversity Medical Center UtrechtUtrechtThe Netherlands
| | - Jan Willem Dankbaar
- Department of RadiologyUniversity Medical Center UtrechtUtrechtThe Netherlands
| | - Inge Stegeman
- Department of Otorhinolaryngology and Head & Neck SurgeryUniversity Medical Center UtrechtUtrechtThe Netherlands
- Rudolf Magnus Institute of NeuroscienceUniversity Medical Center UtrechtUtrechtThe Netherlands
| | | | | | - Luuk M. Janssen
- Department of Head and Neck Surgical OncologyUniversity Medical Center UtrechtUtrechtThe Netherlands
| | - Chris H. Terhaard
- Department of RadiotherapyUniversity Medical Center UtrechtUtrechtThe Netherlands
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Steensma BR, Voogt I, van der Werf AJ, van den Berg CA, Luijten PR, Klomp DW, Raaijmakers AJ. Design of a forward view antenna for prostate imaging at 7 T. NMR IN BIOMEDICINE 2018; 31:e3993. [PMID: 30022543 PMCID: PMC6175442 DOI: 10.1002/nbm.3993] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Revised: 06/07/2018] [Accepted: 06/08/2018] [Indexed: 05/19/2023]
Abstract
PURPOSE To design a forward view antenna for prostate imaging at 7 T, which is placed between the legs of the subject in addition to a dipole array. MATERIALS AND METHODS The forward view antenna is realized by placing a cross-dipole antenna at the end of a small rectangular waveguide. Quadrature drive of the cross-dipole can excite a circularly polarized wave propagating along the axial direction to and from the prostate region. Functioning of the forward view antenna is validated by comparing measurements and simulations. Antenna performance is evaluated by numerical simulations and measurements at 7 T. RESULTS Simulations of B1+ on a phantom are in good correspondence with measurements. Simulations on a human model indicate that the signal-to-noise ratio (SNR), specific absorption rate (SAR) efficiency and SAR increase when adding the forward view antenna to a previously published dipole array. The SNR increases by up to 18% when adding the forward view antenna as a receive antenna to an eight-channel dipole array in vivo. CONCLUSIONS A design for a forward view antenna is presented and evaluated. SNR improvements up to 18% are demonstrated when adding the forward view antenna to a dipole array.
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Affiliation(s)
| | - Ingmar Voogt
- University Medical Center UtrechtUtrechtthe Netherlands
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10
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Coolen BF, Calcagno C, van Ooij P, Fayad ZA, Strijkers GJ, Nederveen AJ. Vessel wall characterization using quantitative MRI: what's in a number? MAGNETIC RESONANCE MATERIALS IN PHYSICS BIOLOGY AND MEDICINE 2017; 31:201-222. [PMID: 28808823 PMCID: PMC5813061 DOI: 10.1007/s10334-017-0644-x] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Revised: 07/04/2017] [Accepted: 07/18/2017] [Indexed: 12/15/2022]
Abstract
The past decade has witnessed the rapid development of new MRI technology for vessel wall imaging. Today, with advances in MRI hardware and pulse sequences, quantitative MRI of the vessel wall represents a real alternative to conventional qualitative imaging, which is hindered by significant intra- and inter-observer variability. Quantitative MRI can measure several important morphological and functional characteristics of the vessel wall. This review provides a detailed introduction to novel quantitative MRI methods for measuring vessel wall dimensions, plaque composition and permeability, endothelial shear stress and wall stiffness. Together, these methods show the versatility of non-invasive quantitative MRI for probing vascular disease at several stages. These quantitative MRI biomarkers can play an important role in the context of both treatment response monitoring and risk prediction. Given the rapid developments in scan acceleration techniques and novel image reconstruction, we foresee the possibility of integrating the acquisition of multiple quantitative vessel wall parameters within a single scan session.
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Affiliation(s)
- Bram F Coolen
- Department of Biomedical Engineering and Physics, Academic Medical Center, PO BOX 22660, 1100 DD, Amsterdam, The Netherlands. .,Department of Radiology, Academic Medical Center, Amsterdam, The Netherlands.
| | - Claudia Calcagno
- Translational and Molecular Imaging Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA.,Department of Radiology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Pim van Ooij
- Department of Radiology, Academic Medical Center, Amsterdam, The Netherlands
| | - Zahi A Fayad
- Translational and Molecular Imaging Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA.,Department of Radiology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Gustav J Strijkers
- Department of Biomedical Engineering and Physics, Academic Medical Center, PO BOX 22660, 1100 DD, Amsterdam, The Netherlands
| | - Aart J Nederveen
- Department of Radiology, Academic Medical Center, Amsterdam, The Netherlands
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11
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Papoutsis K, Li L, Near J, Payne S, Jezzard P. A purpose-built neck coil for black-blood DANTE-prepared carotid artery imaging at 7T. Magn Reson Imaging 2017; 40:53-61. [PMID: 28438710 DOI: 10.1016/j.mri.2017.04.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Revised: 04/12/2017] [Accepted: 04/20/2017] [Indexed: 01/07/2023]
Abstract
Atherosclerotic plaques in the bifurcation of the carotid arteries can pose a significant health risk due to possible plaque rupture and subsequent stroke. The assessment of plaques, and evaluation of the risk they pose, can be performed with Black-Blood (BB) vessel wall magnetic resonance imaging. However, resolution at standard clinical field strengths (up to 3T) is limited, hampering reliable assessment and diagnosis. The aim of this study was to investigate the benefits of 7T MRI using a BB application that has been successful at clinical field strengths. Therefore, for BB imaging, each sequence was preceded with 'Delay Alternating with Nutation for Tailored Excitation' (DANTE) preparation pulses for blood signal suppression. A coil comprising a 4-channel Tx array was designed and built to provide the required excitation coverage for the DANTE train; and a 4-channel Rx array was constructed to target the carotid bifurcation. Human and phantom results showed satisfactory blood suppression and comparable SNR and CNR to 3T, therefore demonstrating the feasibility of the application at 7T. However, the imposed SAR restrictions led to long scan times and subsequent motion artifacts. Thus, more accurate local SAR supervision schemes are required which could lead to a further improvement of BB DANTE vessel wall imaging at 7T.
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Affiliation(s)
- Konstantinos Papoutsis
- FMRIB Centre, Dept of Clinical Neurosciences, University of Oxford, Oxford, UK; Dept of Engineering Science, University of Oxford, Oxford, UK; MR Solutions Ltd, Guildford, UK.
| | - Linqing Li
- Section on Functional Imaging Methods, NIMH, NIH, USA
| | - Jamie Near
- Centre d'Imagerie Cérébrale, Douglas Mental Health University, Montreal, Canada; Dept of Psychiatry, McGill University, Montreal, Canada
| | - Stephen Payne
- Dept of Engineering Science, University of Oxford, Oxford, UK
| | - Peter Jezzard
- FMRIB Centre, Dept of Clinical Neurosciences, University of Oxford, Oxford, UK
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Abstract
Magnetic resonance imaging (MRI) plays a key role in the investigation of cerebrovascular diseases. Compared with computed tomography (CT) and digital subtraction angiography (DSA), its advantages in diagnosing cerebrovascular pathology include its superior tissue contrast, its ability to visualize blood vessels without the use of a contrast agent, and its use of magnetic fields and radiofrequency pulses instead of ionizing radiation. In recent years, ultrahigh field MRI at 7 tesla (7 T) has shown promise in the diagnosis of many cerebrovascular diseases. The increased signal-to-noise ratio (SNR; 2.3x and 4.7x increase compared with 3 and 1.5 T, respectively) and contrast-to-noise ratio (CNR) at this higher field strength can be exploited to obtain a higher spatial resolution and higher lesion conspicuousness, enabling assessment of smaller brain structures and lesions. Cerebrovascular diseases can be assessed at different tissue levels; for instance, changes of the arteries feeding the brain can be visualized to determine the cause of ischemic stroke, regional changes in brain perfusion can be mapped to predict outcome after revascularization, and tissue damage, including old and recent ischemic infarcts, can be evaluated as a marker of ischemic burden. For the purpose of this review, we will discriminate 3 levels of assessment of cerebrovascular diseases using MRI: Pipes, Perfusion, and Parenchyma (3 Ps). The term Pipes refers to the brain-feeding arteries from the heart and aortic arch, upwards to the carotid arteries, vertebral arteries, circle of Willis, and smaller intracranial arterial branches. Perfusion is the amount of blood arriving at the brain tissue level, and includes the vascular reserve and perfusion territories. Parenchyma refers to the acute and chronic burden of brain tissue damage, which includes larger infarcts, smaller microinfarcts, and small vessel disease manifestations such as white matter lesions, lacunar infarcts, and microbleeds. In this review, we will describe the key developments in the last decade of 7-T MRI of cerebrovascular diseases, subdivided for these 3 levels of assessment.
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13
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Henning A, Koning W, Fuchs A, Raaijmakers A, Bluemink JJ, van den Berg CAT, Boer VO, Klomp DWJ. (1) H MRS in the human spinal cord at 7 T using a dielectric waveguide transmitter, RF shimming and a high density receive array. NMR IN BIOMEDICINE 2016; 29:1231-1239. [PMID: 27191947 DOI: 10.1002/nbm.3541] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Revised: 03/22/2016] [Accepted: 03/23/2016] [Indexed: 06/05/2023]
Abstract
Multimodal MRI is the state of the art method for clinical diagnostics and therapy monitoring of the spinal cord, with MRS being an emerging modality that has the potential to detect relevant changes of the spinal cord tissue at an earlier stage and to enhance specificity. Methodological challenges related to the small dimensions and deep location of the human spinal cord inside the human body, field fluctuations due to respiratory motion, susceptibility differences to adjacent tissue such as vertebras and pulsatile flow of the cerebrospinal fluid hinder the clinical application of (1) H MRS to the human spinal cord. Complementary to previous studies that partly addressed these problems, this work aims at enhancing the signal-to-noise ratio (SNR) of (1) H MRS in the human spinal cord. To this end a flexible tight fit high density receiver array and ultra-high field strength (7 T) were combined. A dielectric waveguide and dipole antenna transmission coil allowed for dual channel RF shimming, focusing the RF field in the spinal cord, and an inner-volume saturated semi-LASER sequence was used for robust localization in the presence of B1 (+) inhomogeneity. Herein we report the first 7 T spinal cord (1) H MR spectra, which were obtained in seven independent measurements of 128 averages each in three healthy volunteers. The spectra exhibit high quality (full width at half maximum 0.09 ppm, SNR 7.6) and absence of artifacts and allow for reliable quantification of N-acetyl aspartate (NAA) (NAA/Cr (creatine) 1.31 ± 0.20; Cramér-Rao lower bound (CRLB) 5), total choline containing compounds (Cho) (Cho/Cr 0.32 ± 0.07; CRLB 7), Cr (CRLB 5) and myo-inositol (mI) (mI/Cr 1.08 ± 0.22; CRLB 6) in 7.5 min in the human cervical spinal cord. Thus metabolic information from the spinal cord can be obtained in clinically feasible scan times at 7 T, and its benefit for clinical decision making in spinal cord disorders will be investigated in the future using the presented methodology. Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
- A Henning
- Max Plank Institute for Biological Cybernetics, Tübingen, Germany
- Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland
| | - W Koning
- University Medical Center Utrecht, Utrecht, The Netherlands
| | - A Fuchs
- Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland
| | - A Raaijmakers
- University Medical Center Utrecht, Utrecht, The Netherlands
| | - J J Bluemink
- University Medical Center Utrecht, Utrecht, The Netherlands
| | | | - V O Boer
- University Medical Center Utrecht, Utrecht, The Netherlands
| | - D W J Klomp
- University Medical Center Utrecht, Utrecht, The Netherlands
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14
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Kemper VG, De Martino F, Yacoub E, Goebel R. Variable flip angle 3D-GRASE for high resolution fMRI at 7 tesla. Magn Reson Med 2016; 76:897-904. [PMID: 26390180 PMCID: PMC4801698 DOI: 10.1002/mrm.25979] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Revised: 07/23/2015] [Accepted: 08/19/2015] [Indexed: 11/11/2022]
Abstract
PURPOSE To evaluate the use of variable flip angle refocusing pulse trains in single-shot three-dimensional gradient and spin-echo (3D-GRASE) to reduce blurring and increase the spatial coverage for high spatial resolution T2 -weighted functional MRI at 7 Tesla. METHODS Variable flip angle refocusing schemes in 3D-GRASE were calculated based on extended phase graph theory. The blurring along the slice (partition) direction was evaluated in simulations, as well as phantom and in vivo experiments. Furthermore, temporal stability and functional sensitivity at 0.8 mm isotropic resolution were assessed. RESULTS Variable flip angle refocusing schemes yielded significantly reduced blurring compared with conventional refocusing schemes, with the full width at half maximum being approximately 30-40% narrower. Simultaneously, spatial coverage could be increased by 80%. The temporal signal-to-noise ratio was slightly reduced, but functional sensitivity was largely maintained due to increased functional contrast in the variable flip angle acquisitions. Signal-to-noise ratio and functional sensitivity were reduced more strongly in areas with insufficient radiofrequency transmission indicating higher sensitivity to experimental imperfections. CONCLUSION Variable flip angle refocusing schemes increase usability of 3D-GRASE for high-resolution functional MRI by reducing blurring and allowing increased spatial coverage. Magn Reson Med 76:897-904, 2016. © 2015 Wiley Periodicals, Inc.
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Affiliation(s)
- Valentin G. Kemper
- Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht University, Oxfordlaan 55, 6200 MD Maastricht, The Netherlands
- Maastricht Brain Imaging Center, Maastricht University, Oxfordlaan 55, 6200 MD Maastricht, The Netherlands
| | - Federico De Martino
- Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht University, Oxfordlaan 55, 6200 MD Maastricht, The Netherlands
- Maastricht Brain Imaging Center, Maastricht University, Oxfordlaan 55, 6200 MD Maastricht, The Netherlands
- Center for Magnetic Resonance Research, University of Minnesota Medical School, 2021 Sixth Street SE, Minneapolis, MN 55455, United States of America
| | - Essa Yacoub
- Center for Magnetic Resonance Research, University of Minnesota Medical School, 2021 Sixth Street SE, Minneapolis, MN 55455, United States of America
| | - Rainer Goebel
- Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht University, Oxfordlaan 55, 6200 MD Maastricht, The Netherlands
- Maastricht Brain Imaging Center, Maastricht University, Oxfordlaan 55, 6200 MD Maastricht, The Netherlands
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15
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Quadrature operation of segmented dielectric resonators facilitated with metallic connectors. Magn Reson Med 2016; 77:2431-2437. [DOI: 10.1002/mrm.26301] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Revised: 05/04/2016] [Accepted: 05/19/2016] [Indexed: 11/07/2022]
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16
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Bluemink JJ, Raaijmakers AJE, Koning W, Andreychenko A, Rivera DS, Luijten PR, Klomp DWJ, van den Berg CAT. Dielectric waveguides for ultrahigh field magnetic resonance imaging. Magn Reson Med 2015; 76:1314-24. [DOI: 10.1002/mrm.26007] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2014] [Revised: 09/11/2015] [Accepted: 09/12/2015] [Indexed: 11/09/2022]
Affiliation(s)
- Johanna J. Bluemink
- UMC Utrecht Cancer Center / UMC Utrecht Center for Imaging Sciences, Department of Radiotherapy; University Medical Center Utrecht; The Netherlands
| | - Alexander J. E. Raaijmakers
- UMC Utrecht Cancer Center / UMC Utrecht Center for Imaging Sciences, Department of Radiotherapy; University Medical Center Utrecht; The Netherlands
| | - Wouter Koning
- UMC Utrecht Cancer Center / UMC Utrecht Center for Imaging Sciences, Department of Radiotherapy; University Medical Center Utrecht; The Netherlands
| | - Anna Andreychenko
- UMC Utrecht Cancer Center / UMC Utrecht Center for Imaging Sciences, Department of Radiotherapy; University Medical Center Utrecht; The Netherlands
| | - Debra S. Rivera
- UMC Utrecht Cancer Center / UMC Utrecht Center for Imaging Sciences, Department of Radiotherapy; University Medical Center Utrecht; The Netherlands
| | - Peter R. Luijten
- UMC Utrecht Cancer Center / UMC Utrecht Center for Imaging Sciences, Department of Radiotherapy; University Medical Center Utrecht; The Netherlands
| | - Dennis W. J. Klomp
- UMC Utrecht Cancer Center / UMC Utrecht Center for Imaging Sciences, Department of Radiotherapy; University Medical Center Utrecht; The Netherlands
| | - Cornelis A. T. van den Berg
- UMC Utrecht Cancer Center / UMC Utrecht Center for Imaging Sciences, Department of Radiotherapy; University Medical Center Utrecht; The Netherlands
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Yoshida K, Fukumitsu R, Kurosaki Y, Funaki T, Kikuchi T, Takahashi JC, Takagi Y, Yamagata S, Miyamoto S. The association between expansive arterial remodeling detected by high-resolution MRI in carotid artery stenosis and clinical presentation. J Neurosurg 2015; 123:434-40. [DOI: 10.3171/2014.12.jns14185] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECT
The purpose of the present study was to investigate the association between carotid artery (CA) expansive remodeling (ER) and symptoms of cerebral ischemia.
METHODS
One hundred twenty-two consecutive CAs scheduled for CA endarterectomy (CEA) or CA stent placement (CAS) were retrospectively studied. After excluding 22 CAs (2 were contraindicated for MRI, 8 had near-occlusion, 6 had poor image quality, and 6 had restenosis after CEA or CAS), there were 100 CAs (100 patients) included in the final analysis. The study included 50 symptomatic patients (mean age 73.6 ± 8.9 years, 6 women, mean stenosis 68.5% ± 21.3%) and 50 asymptomatic patients (mean age 72.0 ± 5.9 years, 5 women, mean stenosis 79.4% ± 8.85%). Expansive remodeling was defined as enlargement of the internal carotid artery (ICA) with outward plaque growth. The ER ratio was calculated by dividing the maximum distance between the lumen and the outer borders of the plaque perpendicular to the axis of the ICA by the maximal luminal diameter of the distal ICA at a region unaffected by atherosclerosis using long-axis, high-resolution MRI.
RESULTS
The ER ratio of the atherosclerotic CA was significantly greater than that of normal physiological expansion (carotid bulb; p < 0.01). The ER ratio of symptomatic CA stenosis (median 1.94, interquartile range [IQR] 1.58–2.23) was significantly greater than that of asymptomatic CA stenosis (median 1.52, IQR 1.34–1.81; p = 0.0001). When the cutoff value of the ER ratio was set to 1.88, the sensitivity and specificity to detect symptoms were 0.6 and 0.78, respectively. The ER ratio of symptomatic patients was consistently high regardless of the degree of stenosis.
CONCLUSIONS
There was a significant correlation between ER ratio and ischemic symptoms. The ER ratio might be a potential indicator of vulnerable plaque, which requires further validation by prospective observational study of asymptomatic patients.
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Affiliation(s)
- Kazumichi Yoshida
- 1Department of Neurosurgery, Kyoto University Graduate School of Medicine, Kyoto; and
| | - Ryu Fukumitsu
- 1Department of Neurosurgery, Kyoto University Graduate School of Medicine, Kyoto; and
| | | | - Takeshi Funaki
- 1Department of Neurosurgery, Kyoto University Graduate School of Medicine, Kyoto; and
| | - Takayuki Kikuchi
- 1Department of Neurosurgery, Kyoto University Graduate School of Medicine, Kyoto; and
| | - Jun C. Takahashi
- 1Department of Neurosurgery, Kyoto University Graduate School of Medicine, Kyoto; and
| | - Yasushi Takagi
- 1Department of Neurosurgery, Kyoto University Graduate School of Medicine, Kyoto; and
| | - Sen Yamagata
- 2Department of Neurosurgery, Kurashiki Central Hospital, Okayama, Japan
| | - Susumu Miyamoto
- 1Department of Neurosurgery, Kyoto University Graduate School of Medicine, Kyoto; and
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Increasing the Spatial Resolution of 3T Carotid MRI Has No Beneficial Effect for Plaque Component Measurement Reproducibility. PLoS One 2015; 10:e0130878. [PMID: 26161783 PMCID: PMC4498614 DOI: 10.1371/journal.pone.0130878] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Accepted: 05/26/2015] [Indexed: 11/19/2022] Open
Abstract
Purpose Different in-plane resolutions have been used for carotid 3T MRI. We compared the reproducibility, as well as the within- and between reader variability of high and routinely used spatial resolution in scans of patients with atherosclerotic carotid artery disease. Since no consensus exists about the optimal segmentation method, we analysed all imaging data using two different segmentation methods. Materials and Methods In 31 patient with carotid atherosclerosis a high (0.25 × 0.25 mm2; HR) and routinely used (0.50 × 0.50 mm2; LR) spatial resolution carotid MRI scan were performed within one month. A fully blinded closed and a simultaneously open segmentation were used to quantify the lipid rich necrotic core (LRNC), calcified and loose matrix (LM) plaque area and the fibrous cap (FC) thickness. Results No significant differences were observed between scan-rescan reproducibility for HR versus LR measurements, nor did we find any significant difference between the within-reader and between-reader reproducibility. The same applies for differences between the open and closed reads. All intraclass correlation coefficients between scans and rescans for the LRNC, calcified and LM plaque area, as well as the FC thickness measurements with the open segmentation method were excellent (all above 0.75). Conclusions Increasing the spatial resolution at the expense of the contrast-to-noise ratio does not improve carotid plaque component scan-rescan reproducibility in patients with atherosclerotic carotid disease, nor does using a different segmentation method.
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19
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Kemper VG, De Martino F, Vu AT, Poser BA, Feinberg DA, Goebel R, Yacoub E. Sub-millimeter T2 weighted fMRI at 7 T: comparison of 3D-GRASE and 2D SE-EPI. Front Neurosci 2015; 9:163. [PMID: 25999810 PMCID: PMC4419681 DOI: 10.3389/fnins.2015.00163] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Accepted: 04/20/2015] [Indexed: 11/13/2022] Open
Abstract
Functional magnetic resonance imaging (fMRI) allows studying human brain function non-invasively up to the spatial resolution of cortical columns and layers. Most fMRI acquisitions rely on the blood oxygenation level dependent (BOLD) contrast employing T(*) 2 weighted 2D multi-slice echo-planar imaging (EPI). At ultra-high magnetic field (i.e., 7 T and above), it has been shown experimentally and by simulation, that T2 weighted acquisitions yield a signal that is spatially more specific to the site of neuronal activity at the cost of functional sensitivity. This study compared two T2 weighted imaging sequences, inner-volume 3D Gradient-and-Spin-Echo (3D-GRASE) and 2D Spin-Echo EPI (SE-EPI), with evaluation of their imaging point-spread function (PSF), functional specificity, and functional sensitivity at sub-millimeter resolution. Simulations and measurements of the imaging PSF revealed that the strongest anisotropic blurring in 3D-GRASE (along the second phase-encoding direction) was about 60% higher than the strongest anisotropic blurring in 2D SE-EPI (along the phase-encoding direction). In a visual paradigm, the BOLD sensitivity of 3D-GRASE was found to be superior due to its higher temporal signal-to-noise ratio (tSNR). High resolution cortical depth profiles suggested that the contrast mechanisms are similar between the two sequences, however, 2D SE-EPI had a higher surface bias owing to the higher T(*) 2 contribution of the longer in-plane EPI echo-train for full field of view compared to the reduced field of view of zoomed 3D-GRASE.
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Affiliation(s)
- Valentin G. Kemper
- Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht UniversityMaastricht, Netherlands
- Department of Cognitive Neuroscience, Maastricht Brain Imaging Center, Maastricht UniversityMaastricht, Netherlands
| | - Federico De Martino
- Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht UniversityMaastricht, Netherlands
- Department of Cognitive Neuroscience, Maastricht Brain Imaging Center, Maastricht UniversityMaastricht, Netherlands
- Department of Radiology, Center for Magnetic Resonance Research, University of Minnesota Medical SchoolMinneapolis, MN, USA
| | - An T. Vu
- Department of Radiology, Center for Magnetic Resonance Research, University of Minnesota Medical SchoolMinneapolis, MN, USA
| | - Benedikt A. Poser
- Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht UniversityMaastricht, Netherlands
- Department of Cognitive Neuroscience, Maastricht Brain Imaging Center, Maastricht UniversityMaastricht, Netherlands
| | - David A. Feinberg
- Advanced MRI TechnologiesSebastopol, CA, USA
- Brain Imaging Center, Helen Wills Institute for Neuroscience, University of California, BerkeleyBerkeley, CA, USA
| | - Rainer Goebel
- Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht UniversityMaastricht, Netherlands
- Department of Cognitive Neuroscience, Maastricht Brain Imaging Center, Maastricht UniversityMaastricht, Netherlands
- Department of Neuroimaging and Neuromodeling, Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences (KNAW)Amsterdam, Netherlands
| | - Essa Yacoub
- Department of Radiology, Center for Magnetic Resonance Research, University of Minnesota Medical SchoolMinneapolis, MN, USA
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20
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Phase-Sensitive Dual-Inversion Recovery for Accelerated Carotid Vessel Wall Imaging. Invest Radiol 2015; 50:135-43. [DOI: 10.1097/rli.0000000000000110] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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21
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Seven-Tesla Magnetic Resonance Imaging of Atherosclerotic Plaque in the Significantly Stenosed Carotid Artery. Invest Radiol 2014; 49:749-57. [DOI: 10.1097/rli.0000000000000079] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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22
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van Veluw SJ, Fracasso A, Visser F, Spliet WGM, Luijten PR, Biessels GJ, Zwanenburg JJM. FLAIR images at 7 Tesla MRI highlight the ependyma and the outer layers of the cerebral cortex. Neuroimage 2014; 104:100-9. [PMID: 25315783 DOI: 10.1016/j.neuroimage.2014.10.011] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Revised: 10/01/2014] [Accepted: 10/04/2014] [Indexed: 11/17/2022] Open
Abstract
OBJECTIVES Fluid-attenuated inversion recovery (FLAIR) imaging is an important clinical 'work horse' for brain MRI and has proven to facilitate imaging of both intracortical lesions as well as cortical layers at 7T MRI. A prominent observation on 7T FLAIR images is a hyperintense rim at the cortical surface and around the ventricles. We aimed to clarify the anatomical correlates and underlying contrast mechanisms of this hyperintense rim. MATERIALS AND METHODS Two experiments with post-mortem human brain tissue were performed. FLAIR and T2-weighted images were obtained at typical in vivo (0.8mm isotropic) and high resolution (0.25mm isotropic). At one location the cortical surface was partly removed, and scanned again. Imaging was followed by histological and immunohistochemical analysis. Additionally, several simulations were performed to evaluate the potential contribution from an artifact due to water diffusion. RESULTS The hyperintense rim corresponded to the outer - glia rich - layer of the cortex and disappeared upon removal of that layer. At the ventricles, the rim corresponded to the ependymal layer, and was not present at white matter/fluid borders at an artificial cut. The simulations supported the hypothesis that the hyperintense rim reflects the tissue properties in the outer cortical layers (or ependymal layer for the ventricles), and is not merely an artifact, although not all observations were explained by the simulated model of the contrast mechanism. CONCLUSIONS 7T FLAIR seems to amplify the signal from layers I-III of the cortex and the ependyma around the ventricles. Although diffusion of water from layer I into CSF does contribute to this effect, a long T2 relaxation time constant in layer I, and probably also layer II-III, is most likely the major contributor, since the rim disappears upon removal of that layer. This knowledge can help the interpretation of imaging results in cortical development and in patients with cortical pathology.
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Affiliation(s)
- Susanne J van Veluw
- Department of Neurology, Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht, the Netherlands.
| | - Alessio Fracasso
- Experimental Psychology, Helmholtz Institute, Utrecht University, Utrecht, the Netherlands
| | - Fredy Visser
- Department of Radiology, University Medical Center Utrecht, Utrecht, the Netherlands; Philips Healthcare, Best, the Netherlands
| | - Wim G M Spliet
- Department of Pathology, University Medical Center Utrecht, Utrecht, the Netherlands
| | - Peter R Luijten
- Department of Radiology, University Medical Center Utrecht, Utrecht, the Netherlands
| | - Geert Jan Biessels
- Department of Neurology, Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht, the Netherlands
| | - Jaco J M Zwanenburg
- Department of Radiology, University Medical Center Utrecht, Utrecht, the Netherlands
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23
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Aussenhofer SA, Webb AG. An eight-channel transmit/receive array of TE01 mode high permittivity ceramic resonators for human imaging at 7T. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2014; 243:122-129. [PMID: 24818565 DOI: 10.1016/j.jmr.2014.04.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Revised: 03/31/2014] [Accepted: 04/03/2014] [Indexed: 06/03/2023]
Abstract
This study describes the design, construction and operation of a new type of transmit/receive array using ceramic resonators operating in a transverse electromagnetic (TE) mode. Single element function and performance at 298.1MHz (7T) are analyzed and compared to a lumped element design loop coil with comparable geometry. The results show that ceramic resonators working in the TE01δ mode configuration produce similar efficiency, defined as the transmit magnetic field (B1(+)) per square root of the specific absorption rate (SAR), to conventional surface coils. An array consisting of eight ceramic elements was then designed to operate in transmit/receive mode. This array was driven via power/phase splitters by two independent transmit channels and functional cardiac images were produced from a number of healthy volunteers.
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Affiliation(s)
- S A Aussenhofer
- C.J. Gorter Center for High Field MRI, Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands
| | - A G Webb
- C.J. Gorter Center for High Field MRI, Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands.
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24
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Koning W, de Rotte AA, Bluemink JJ, van der Velden TA, Luijten PR, Klomp DW, Zwanenburg JJ. MRI of the carotid artery at 7 Tesla: Quantitative comparison with 3 Tesla. J Magn Reson Imaging 2014; 41:773-80. [DOI: 10.1002/jmri.24601] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2013] [Accepted: 01/25/2014] [Indexed: 11/11/2022] Open
Affiliation(s)
- Wouter Koning
- Department of Radiology; UMC Utrecht; The Netherlands
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25
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Nederveen AJ, Avril S, Speelman L. MRI strain imaging of the carotid artery: present limitations and future challenges. J Biomech 2014; 47:824-33. [PMID: 24468207 DOI: 10.1016/j.jbiomech.2014.01.014] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/13/2014] [Indexed: 11/18/2022]
Abstract
Rupture of atherosclerotic plaques in the carotid artery is a main cause of stroke. Current diagnostics are not sufficient to identify all rupture-prone plaques, and studies have shown that biomechanical factors improve current plaque risk assessment. Strain imaging may be a valuable contribution to this risk assessment. MRI is a versatile imaging technique that offers various methods that are capable of measuring tissue strain. In this review, MR imaging techniques with displacement (DENSE), velocity (PC MRI), or strain (SENC) encoding protocols are discussed, together with post-processing techniques based on time-resolved MRI data. Although several MRI techniques are being developed to improve time-resolved MR imaging, current technical limitations related to spatial and temporal resolutions render MRI strain imaging currently unfit for carotid plaque strain evaluation. A novel approach using non-rigid image registration of MR images to determine strain in carotid arteries based on black blood cine MRI is proposed in this review. This and other post-processing techniques based on time-resolved MRI data may provide a good estimate of plaque strain, but are also dependent on the spatial and temporal resolution of the MR images. However, they seem to be the most promising approach for MRI based plaque strain analysis in the near future.
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Affiliation(s)
- Aart J Nederveen
- Department of Radiology, Academic Medical Center Amsterdam, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands.
| | - Stéphane Avril
- Center for Biomedical and Healthcare Engineering, Ecole Nationale Supérieure des Mines de Saint-Étienne, France
| | - Lambert Speelman
- Department of Biomedical Engineering, Erasmus MC Rotterdam, The Netherlands
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