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Campbell-Washburn AE, Varghese J, Nayak KS, Ramasawmy R, Simonetti OP. Cardiac MRI at Low Field Strengths. J Magn Reson Imaging 2024; 59:412-430. [PMID: 37530545 PMCID: PMC10834858 DOI: 10.1002/jmri.28890] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Revised: 06/16/2023] [Accepted: 06/16/2023] [Indexed: 08/03/2023] Open
Abstract
Cardiac MR imaging is well established for assessment of cardiovascular structure and function, myocardial scar, quantitative flow, parametric mapping, and myocardial perfusion. Despite the clear evidence supporting the use of cardiac MRI for a wide range of indications, it is underutilized clinically. Recent developments in low-field MRI technology, including modern data acquisition and image reconstruction methods, are enabling high-quality low-field imaging that may improve the cost-benefit ratio for cardiac MRI. Studies to-date confirm that low-field MRI offers high measurement concordance and consistent interpretation with clinical imaging for several routine sequences. Moreover, low-field MRI may enable specific new clinical opportunities for cardiac imaging such as imaging near metal implants, MRI-guided interventions, combined cardiopulmonary assessment, and imaging of patients with severe obesity. In this review, we discuss the recent progress in low-field cardiac MRI with a focus on technical developments and early clinical validation studies. EVIDENCE LEVEL: 5 TECHNICAL EFFICACY: Stage 1.
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Affiliation(s)
- Adrienne E Campbell-Washburn
- Cardiovascular Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda MD USA
| | - Juliet Varghese
- Department of Biomedical Engineering, The Ohio State University, Columbus, OH, USA
| | - Krishna S Nayak
- Ming Hsieh Department of Electrical and Computer Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles, California, USA
- Alfred Mann Department of Biomedical Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles, California, USA
| | - Rajiv Ramasawmy
- Cardiovascular Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda MD USA
| | - Orlando P Simonetti
- Division of Cardiovascular Medicine, Department of Internal Medicine, College of Medicine, The Ohio State University, Columbus, OH, USA
- Department of Radiology, The Ohio State University, Columbus, Ohio, USA
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2
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Tian Y, Nayak KS. New clinical opportunities of low-field MRI: heart, lung, body, and musculoskeletal. MAGMA (NEW YORK, N.Y.) 2024; 37:1-14. [PMID: 37902898 PMCID: PMC10876830 DOI: 10.1007/s10334-023-01123-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Revised: 09/28/2023] [Accepted: 10/05/2023] [Indexed: 11/01/2023]
Abstract
Contemporary whole-body low-field MRI scanners (< 1 T) present new and exciting opportunities for improved body imaging. The fundamental reason is that the reduced off-resonance and reduced SAR provide substantially increased flexibility in the design of MRI pulse sequences. Promising body applications include lung parenchyma imaging, imaging adjacent to metallic implants, cardiac imaging, and dynamic imaging in general. The lower cost of such systems may make MRI favorable for screening high-risk populations and population health research, and the more open configurations allowed may prove favorable for obese subjects and for pregnant women. This article summarizes promising body applications for contemporary whole-body low-field MRI systems, with a focus on new platforms developed within the past 5 years. This is an active area of research, and one can expect many improvements as MRI physicists fully explore the landscape of pulse sequences that are feasible, and as clinicians apply these to patient populations.
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Affiliation(s)
- Ye Tian
- Ming Hsieh Department of Electrical and Computer Engineering, Viterbi School of Engineering, University of Southern California, 3740 McClintock Ave, EEB 406, Los Angeles, CA, 90089-2564, USA.
| | - Krishna S Nayak
- Ming Hsieh Department of Electrical and Computer Engineering, Viterbi School of Engineering, University of Southern California, 3740 McClintock Ave, EEB 406, Los Angeles, CA, 90089-2564, USA
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3
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Guenthner C, Peereboom SM, Dillinger H, McGrath C, Albannay MM, Vishnevskiy V, Fuetterer M, Luechinger R, Jenneskens T, Sturzenegger U, Overweg J, Koken P, Börnert P, Kozerke S. Ramping down a clinical 3 T scanner: a journey into MRI and MRS at 0.75 T. MAGMA (NEW YORK, N.Y.) 2023:10.1007/s10334-023-01089-9. [PMID: 37171689 PMCID: PMC10386956 DOI: 10.1007/s10334-023-01089-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 03/06/2023] [Accepted: 04/01/2023] [Indexed: 05/13/2023]
Abstract
OBJECT Lower-field MR is reemerging as a viable, potentially cost-effective alternative to high-field MR, thanks to advances in hardware, sequence design, and reconstruction over the past decades. Evaluation of lower field strengths, however, is limited by the availability of lower-field systems on the market and their considerable procurement costs. In this work, we demonstrate a low-cost, temporary alternative to purchasing a dedicated lower-field MR system. MATERIALS AND METHODS By ramping down an existing clinical 3 T MRI system to 0.75 T, proton signals can be acquired using repurposed 13C transmit/receive hardware and the multi-nuclei spectrometer interface. We describe the ramp-down procedure and necessary software and hardware changes to the system. RESULTS Apart from presenting system characterization results, we show in vivo examples of cardiac cine imaging, abdominal two- and three-point Dixon-type water/fat separation, water/fat-separated MR Fingerprinting, and point-resolved spectroscopy. In addition, the ramp-down approach allows unique comparisons of, e.g., gradient fidelity of the same MR system operated at different field strengths using the same receive chain, gradient coils, and amplifiers. DISCUSSION Ramping down an existing MR system may be seen as a viable alternative for lower-field MR research in groups that already own multi-nuclei hardware and can also serve as a testing platform for custom-made multi-nuclei transmit/receive coils.
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Affiliation(s)
- Christian Guenthner
- Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland.
| | | | - Hannes Dillinger
- Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland
| | - Charles McGrath
- Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland
| | | | - Valery Vishnevskiy
- Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland
| | - Max Fuetterer
- Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland
| | - Roger Luechinger
- Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland
| | | | | | | | | | | | - Sebastian Kozerke
- Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland
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4
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Chowdhury MH, Chowdhury MEH, Khan MS, Ullah MA, Mahmud S, Khandakar A, Hassan A, Tahir AM, Hasan A. Self-Attention MHDNet: A Novel Deep Learning Model for the Detection of R-Peaks in the Electrocardiogram Signals Corrupted with Magnetohydrodynamic Effect. Bioengineering (Basel) 2023; 10:bioengineering10050542. [PMID: 37237612 DOI: 10.3390/bioengineering10050542] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 04/19/2023] [Accepted: 04/21/2023] [Indexed: 05/28/2023] Open
Abstract
Magnetic resonance imaging (MRI) is commonly used in medical diagnosis and minimally invasive image-guided operations. During an MRI scan, the patient's electrocardiogram (ECG) may be required for either gating or patient monitoring. However, the challenging environment of an MRI scanner, with its several types of magnetic fields, creates significant distortions of the collected ECG data due to the Magnetohydrodynamic (MHD) effect. These changes can be seen as irregular heartbeats. These distortions and abnormalities hamper the detection of QRS complexes, and a more in-depth diagnosis based on the ECG. This study aims to reliably detect R-peaks in the ECG waveforms in 3 Tesla (T) and 7T magnetic fields. A novel model, Self-Attention MHDNet, is proposed to detect R peaks from the MHD corrupted ECG signal through 1D-segmentation. The proposed model achieves a recall and precision of 99.83% and 99.68%, respectively, for the ECG data acquired in a 3T setting, while 99.87% and 99.78%, respectively, in a 7T setting. This model can thus be used in accurately gating the trigger pulse for the cardiovascular functional MRI.
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Affiliation(s)
- Moajjem Hossain Chowdhury
- Department of Electrical, Electronic and System Engineering, Universiti Kebangsaan Malaysia, Bangi 43600, Malaysia
| | | | | | - Md Asad Ullah
- Department of Mechanical and Industrial Engineering, Qatar University, Doha 2713, Qatar
| | - Sakib Mahmud
- Department of Electrical Engineering, Qatar University, Doha 2713, Qatar
| | - Amith Khandakar
- Department of Electrical Engineering, Qatar University, Doha 2713, Qatar
| | - Alvee Hassan
- Department of Biomedical Engineering, Military Institute of Science and Technology, Mirpur Cantonment, Dhaka 1216, Bangladesh
| | - Anas M Tahir
- Department of Electrical Engineering, Qatar University, Doha 2713, Qatar
| | - Anwarul Hasan
- Department of Mechanical and Industrial Engineering, Qatar University, Doha 2713, Qatar
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5
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Muacevic A, Adler JR. Autonomic Nervous System Monitoring: Cardiac Magnetic Resonance Imaging Data as a Surrogate for Autonomic Data in Children. Cureus 2022; 14:e32014. [PMID: 36589173 PMCID: PMC9797874 DOI: 10.7759/cureus.32014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/15/2022] [Indexed: 11/30/2022] Open
Abstract
Perioperative autonomic nervous system (ANS) measurements are evolving toward increasing import and utility. We present a three-year-old male with Down Syndrome who underwent ambulatory autonomic monitoring during surgery followed by cardiac magnetic resonance (CMR) imaging. Autonomic data from both environments are compared to age-related norms. We are the first to describe a method for acquiring and trending autonomic data from clinically indicated CMR scans in order to monitor autonomic function. These data are proof of concept for the use of routinely collected CMR data as a surrogate for autonomic data in children, noting differences in the autonomic effects of anesthetic techniques.
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Roy CW, Di Sopra L, Whitehead KK, Piccini D, Yerly J, Heerfordt J, Ghosh RM, Fogel MA, Stuber M. Free-running cardiac and respiratory motion-resolved 5D whole-heart coronary cardiovascular magnetic resonance angiography in pediatric cardiac patients using ferumoxytol. J Cardiovasc Magn Reson 2022; 24:39. [PMID: 35754040 PMCID: PMC9235103 DOI: 10.1186/s12968-022-00871-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Accepted: 06/10/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Coronary cardiovascular magnetic resonance angiography (CCMRA) of congenital heart disease (CHD) in pediatric patients requires accurate planning, adequate sequence parameter adjustments, lengthy scanning sessions, and significant involvement from highly trained personnel. Anesthesia and intubation are commonplace to minimize movements and control respiration in younger subjects. To address the above concerns and provide a single-click imaging solution, we applied our free-running framework for fully self-gated (SG) free-breathing 5D whole-heart CCMRA to CHD patients after ferumoxytol injection. We tested the hypothesis that spatial and motion resolution suffice to visualize coronary artery ostia in a cohort of CHD subjects, both for intubated and free-breathing acquisitions. METHODS In 18 pediatric CHD patients, non-electrocardiogram (ECG) triggered 5D free-running gradient echo CCMRA with whole-heart 1 mm3 isotropic spatial resolution was performed in seven minutes on a 1.5T CMR scanner. Eleven patients were anesthetized and intubated, while seven were breathing freely without anesthesia. All patients were slowly injected with ferumoxytol (4 mg/kg) over 15 minutes. Cardiac and respiratory motion-resolved 5D images were reconstructed with a fully SG approach. To evaluate the performance of motion resolution, visibility of coronary artery origins was assessed. Intubated and free-breathing patient sub-groups were compared for image quality using coronary artery length and conspicuity as well as lung-liver interface sharpness. RESULTS Data collection using the free-running framework was successful in all patients in less than 8 min; scan planning was very simple without the need for parameter adjustments, while no ECG lead placement and triggering was required. From the resulting SG 5D motion-resolved reconstructed images, coronary artery origins could be retrospectively extracted in 90% of the cases. These general findings applied to both intubated and free-breathing pediatric patients (no difference in terms of lung-liver interface sharpness), while image quality and coronary conspicuity between both cohorts was very similar. CONCLUSIONS A simple-to-use push-button framework for 5D whole-heart CCMRA was successfully employed in pediatric CHD patients with ferumoxytol injection. This approach, working without any external gating and for a wide range of heart rates and body sizes provided excellent definition of cardiac anatomy for both intubated and free-breathing patients.
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Affiliation(s)
- Christopher W. Roy
- Department of Diagnostic and Interventional Radiology, Lausanne University Hospital (CHUV) and University of Lausanne (UNIL), Rue de Bugnon 46, BH-8-84, 1011 Lausanne, Switzerland
| | - Lorenzo Di Sopra
- Department of Diagnostic and Interventional Radiology, Lausanne University Hospital (CHUV) and University of Lausanne (UNIL), Rue de Bugnon 46, BH-8-84, 1011 Lausanne, Switzerland
| | - Kevin K. Whitehead
- Division of Cardiology, Department of Pediatrics, The Children’s Hospital of Philadelphia, University of Pennsylvania Perelman School of Medicine, Philadelphia, USA
| | - Davide Piccini
- Department of Diagnostic and Interventional Radiology, Lausanne University Hospital (CHUV) and University of Lausanne (UNIL), Rue de Bugnon 46, BH-8-84, 1011 Lausanne, Switzerland
- Advanced Clinical Imaging Technology, Siemens Healthcare AG, Lausanne, Switzerland
| | - Jérôme Yerly
- Department of Diagnostic and Interventional Radiology, Lausanne University Hospital (CHUV) and University of Lausanne (UNIL), Rue de Bugnon 46, BH-8-84, 1011 Lausanne, Switzerland
- Center for Biomedical Imaging (CIBM), Lausanne, Switzerland
| | - John Heerfordt
- Department of Diagnostic and Interventional Radiology, Lausanne University Hospital (CHUV) and University of Lausanne (UNIL), Rue de Bugnon 46, BH-8-84, 1011 Lausanne, Switzerland
- Advanced Clinical Imaging Technology, Siemens Healthcare AG, Lausanne, Switzerland
| | - Reena M. Ghosh
- Division of Cardiology, Department of Pediatrics, The Children’s Hospital of Philadelphia, University of Pennsylvania Perelman School of Medicine, Philadelphia, USA
| | - Mark A. Fogel
- Division of Cardiology, Department of Pediatrics, The Children’s Hospital of Philadelphia, University of Pennsylvania Perelman School of Medicine, Philadelphia, USA
| | - Matthias Stuber
- Department of Diagnostic and Interventional Radiology, Lausanne University Hospital (CHUV) and University of Lausanne (UNIL), Rue de Bugnon 46, BH-8-84, 1011 Lausanne, Switzerland
- Center for Biomedical Imaging (CIBM), Lausanne, Switzerland
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7
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Wang W, Weiss S, den Brinker AC, Wuelbern JH, Tormo AGI, Pappous I, Senegas J. Fundamentals of Camera-PPG based Magnetic Resonance Imaging. IEEE J Biomed Health Inform 2021; 26:4378-4389. [PMID: 34928810 DOI: 10.1109/jbhi.2021.3136603] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
In Magnetic Resonance Imaging (MRI), cardiac triggering that synchronizes data acquisition with cardiac contractions is an essential technique for acquiring high-quality images. Triggering is typically based on the Electrocardiogram (ECG) signal (e.g. R-peak). Since ECG acquisition involves extra workflow steps like electrode placement and ECG signals are usually disturbed by magnetic fields in high Magnetic Resonance (MR) systems, we explored camera-based photoplethysmography (PPG) as an alternative. We used the in-bore camera of a clinical MR system to investigate the feasibility and challenges of camera-based cardiac triggering. Data from ECG, finger oximeter and camera were synchronously collected. We found that that camera-PPG provides a higher availability of signal (and trigger) measurement, and the PPG signals measured from the forehead show considerably less delay w.r.t. the coupled ECG R-peak than the finger PPG signals in terms of trigger detection. The insights obtained in this study provide a basis for an envisioned system design phase.
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Falcão MBL, Di Sopra L, Ma L, Bacher M, Yerly J, Speier P, Rutz T, Prša M, Markl M, Stuber M, Roy CW. Pilot tone navigation for respiratory and cardiac motion-resolved free-running 5D flow MRI. Magn Reson Med 2021; 87:718-732. [PMID: 34611923 PMCID: PMC8627452 DOI: 10.1002/mrm.29023] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 08/17/2021] [Accepted: 09/03/2021] [Indexed: 11/07/2022]
Abstract
Purpose In this work, we integrated the pilot tone (PT) navigation system into a reconstruction framework for respiratory and cardiac motion‐resolved 5D flow. We tested the hypotheses that PT would provide equivalent respiratory curves, cardiac triggers, and corresponding flow measurements to a previously established self‐gating (SG) technique while being independent from changes to the acquisition parameters. Methods Fifteen volunteers and 9 patients were scanned with a free‐running 5D flow sequence, with PT integrated. Respiratory curves and cardiac triggers from PT and SG were compared across all subjects. Flow measurements from 5D flow reconstructions using both PT and SG were compared to each other and to a reference electrocardiogram‐gated and respiratory triggered 4D flow acquisition. Radial trajectories with variable readouts per interleave were also tested in 1 subject to compare cardiac trigger quality between PT and SG. Results The correlation between PT and SG respiratory curves were 0.95 ± 0.06 for volunteers and 0.95 ± 0.04 for patients. Heartbeat duration measurements in volunteers and patients showed a bias to electrocardiogram measurements of, respectively, 0.16 ± 64.94 ms and 0.01 ± 39.29 ms for PT versus electrocardiogram and of 0.24 ± 63.68 ms and 0.09 ± 32.79 ms for SG versus electrocardiogram. No significant differences were reported for the flow measurements between 5D flow PT and from 5D flow SG. A decrease in the cardiac triggering quality of SG was observed for increasing readouts per interleave, whereas PT quality remained constant. Conclusion PT has been successfully integrated in 5D flow MRI and has shown equivalent results to the previously described 5D flow SG technique, while being completely acquisition‐independent.
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Affiliation(s)
- Mariana B L Falcão
- Department of Diagnostic and Interventional Radiology, Lausanne University Hospital (CHUV) and University of Lausanne (UNIL), Lausanne, Switzerland
| | - Lorenzo Di Sopra
- Department of Diagnostic and Interventional Radiology, Lausanne University Hospital (CHUV) and University of Lausanne (UNIL), Lausanne, Switzerland
| | - Liliana Ma
- Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA.,Department of Biomedical Engineering, Northwestern University, Chicago, Illinois, USA
| | - Mario Bacher
- Department of Diagnostic and Interventional Radiology, Lausanne University Hospital (CHUV) and University of Lausanne (UNIL), Lausanne, Switzerland.,Siemens Healthcare GmbH, Erlangen, Germany.,Advanced Clinical Imaging Technology, Siemens Healthcare AG, Lausanne, Switzerland
| | - Jérôme Yerly
- Department of Diagnostic and Interventional Radiology, Lausanne University Hospital (CHUV) and University of Lausanne (UNIL), Lausanne, Switzerland.,Center for Biomedical Imaging (CIBM), Lausanne, Switzerland
| | | | - Tobias Rutz
- Service of Cardiology, Centre de Resonance Magnétique Cardiaque (CRMC), Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
| | - Milan Prša
- Woman-Mother-Child Department, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
| | - Michael Markl
- Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA.,Department of Biomedical Engineering, Northwestern University, Chicago, Illinois, USA
| | - Matthias Stuber
- Department of Diagnostic and Interventional Radiology, Lausanne University Hospital (CHUV) and University of Lausanne (UNIL), Lausanne, Switzerland.,Center for Biomedical Imaging (CIBM), Lausanne, Switzerland
| | - Christopher W Roy
- Department of Diagnostic and Interventional Radiology, Lausanne University Hospital (CHUV) and University of Lausanne (UNIL), Lausanne, Switzerland
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9
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Hoppe E, Wetzl J, Yoon SS, Bacher M, Roser P, Stimpel B, Preuhs A, Maier A. Deep Learning-Based ECG-Free Cardiac Navigation for Multi-Dimensional and Motion-Resolved Continuous Magnetic Resonance Imaging. IEEE TRANSACTIONS ON MEDICAL IMAGING 2021; 40:2105-2117. [PMID: 33848244 DOI: 10.1109/tmi.2021.3073091] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
For the clinical assessment of cardiac vitality, time-continuous tomographic imaging of the heart is used. To further detect e.g., pathological tissue, multiple imaging contrasts enable a thorough diagnosis using magnetic resonance imaging (MRI). For this purpose, time-continous and multi-contrast imaging protocols were proposed. The acquired signals are binned using navigation approaches for a motion-resolved reconstruction. Mostly, external sensors such as electrocardiograms (ECG) are used for navigation, leading to additional workflow efforts. Recent sensor-free approaches are based on pipelines requiring prior knowledge, e.g., typical heart rates. We present a sensor-free, deep learning-based navigation that diminishes the need for manual feature engineering or the necessity of prior knowledge compared to previous works. A classifier is trained to estimate the R-wave timepoints in the scan directly from the imaging data. Our approach is evaluated on 3-D protocols for continuous cardiac MRI, acquired in-vivo and free-breathing with single or multiple imaging contrasts. We achieve an accuracy of > 98% on previously unseen subjects, and a well comparable image quality with the state-of-the-art ECG-based reconstruction. Our method enables an ECG-free workflow for continuous cardiac scans with simultaneous anatomic and functional imaging with multiple contrasts. It can be potentially integrated without adapting the sampling scheme to other continuous sequences by using the imaging data for navigation and reconstruction.
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10
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A simple, open and extensible gating Control unit for cardiac and respiratory synchronisation control in small animal MRI and demonstration of its robust performance in steady-state maintained CINE-MRI. Magn Reson Imaging 2021; 81:1-9. [PMID: 33905831 PMCID: PMC8274699 DOI: 10.1016/j.mri.2021.04.012] [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: 12/11/2020] [Accepted: 04/22/2021] [Indexed: 11/22/2022]
Abstract
Prospective cardiac gating during MRI is hampered by electromagnetic induction from the rapidly switched imaging gradients into the ECG detection circuit. This is particularly challenging in small animal MRI, as higher heart rates combined with a smaller myocardial mass render routine ECG detection challenging. We have developed an open-hardware system that enables continuously running MRI scans to be performed in conjunction with cardio-respiratory gating such that the relaxation-weighted steady state magnetisation is maintained throughout the scan. This requires that the R-wave must be detected reliably even in the presence of rapidly switching gradients, and that data previously acquired that were corrupted by respiratory motion re-acquired. The accurately maintained steady-state magnetisation leads to an improvement in image quality and removes alterations in intensity that may otherwise occur throughout the cardiac cycle and impact upon automated image analysis. We describe the hardware required to enable this and demonstrate its application and robust performance using prospectively cardio-respiratory gated CINE imaging that is operated at a single, constant TR. Schematics, technical drawings, component listing and assembly instructions are made publicly available.
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11
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Ladrova M, Martinek R, Nedoma J, Hanzlikova P, Nelson MD, Kahankova R, Brablik J, Kolarik J. Monitoring and Synchronization of Cardiac and Respiratory Traces in Magnetic Resonance Imaging: A Review. IEEE Rev Biomed Eng 2021; 15:200-221. [PMID: 33513108 DOI: 10.1109/rbme.2021.3055550] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Synchronization of human vital signs, namely the cardiac cycle and respiratory excursions, is necessary during magnetic resonance imaging of the cardiovascular system and the abdominal cavity to achieve optimal image quality with minimized artifacts. This review summarizes techniques currently available in clinical practice, as well as methods under development, outlines the benefits and disadvantages of each approach, and offers some unique solutions for consideration.
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12
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Troelstra MA, Runge JH, Burnhope E, Polcaro A, Guenthner C, Schneider T, Razavi R, Ismail TF, Martorell J, Sinkus R. Shear wave cardiovascular MR elastography using intrinsic cardiac motion for transducer-free non-invasive evaluation of myocardial shear wave velocity. Sci Rep 2021; 11:1403. [PMID: 33446701 PMCID: PMC7809276 DOI: 10.1038/s41598-020-79231-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Accepted: 11/30/2020] [Indexed: 01/29/2023] Open
Abstract
Changes in myocardial stiffness may represent a valuable biomarker for early tissue injury or adverse remodeling. In this study, we developed and validated a novel transducer-free magnetic resonance elastography (MRE) approach for quantifying myocardial biomechanics using aortic valve closure-induced shear waves. Using motion-sensitized two-dimensional pencil beams, septal shear waves were imaged at high temporal resolution. Shear wave speed was measured using time-of-flight of waves travelling between two pencil beams and corrected for geometrical biases. After validation in phantoms, results from twelve healthy volunteers and five cardiac patients (two left ventricular hypertrophy, two myocardial infarcts, and one without confirmed pathology) were obtained. Torsional shear wave speed in the phantom was 3.0 ± 0.1 m/s, corresponding with reference speeds of 2.8 ± 0.1 m/s. Geometrically-biased flexural shear wave speed was 1.9 ± 0.1 m/s, corresponding with simulation values of 2.0 m/s. Corrected septal shear wave speeds were significantly higher in patients than healthy volunteers [14.1 (11.0-15.8) m/s versus 3.6 (2.7-4.3) m/s, p = 0.001]. The interobserver 95%-limits-of-agreement in healthy volunteers were ± 1.3 m/s and interstudy 95%-limits-of-agreement - 0.7 to 1.2 m/s. In conclusion, myocardial shear wave speed can be measured using aortic valve closure-induced shear waves, with cardiac patients showing significantly higher shear wave speeds than healthy volunteers. This non-invasive measure may provide valuable insights into the pathophysiology of heart failure.
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Affiliation(s)
- Marian Amber Troelstra
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, UK
- Department of Radiology and Nuclear Medicine, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
| | - Jurgen Henk Runge
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, UK
- Department of Radiology and Nuclear Medicine, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
| | - Emma Burnhope
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, UK
- Department of Cardiology, Guy's and St Thomas' NHS Foundation Trust, London, UK
| | - Alessandro Polcaro
- Department of Chemical Engineering and Material Sciences, IQS School of Engineering, Universitat Ramon Llull, Via Augusta 390, 08017, Barcelona, Spain
| | - Christian Guenthner
- Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland
- Philips Research, Hamburg, Germany
| | - Torben Schneider
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, UK
- Philips, Guildford, UK
| | - Reza Razavi
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, UK
| | - Tevfik F Ismail
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, UK
- Department of Cardiology, Guy's and St Thomas' NHS Foundation Trust, London, UK
| | - Jordi Martorell
- Department of Chemical Engineering and Material Sciences, IQS School of Engineering, Universitat Ramon Llull, Via Augusta 390, 08017, Barcelona, Spain.
| | - Ralph Sinkus
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, UK
- Inserm U1148, LVTS, University Paris Diderot, University Paris 13, Paris, France
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13
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ECG-gated MR angiography provides better reproducibility for standard aortic measurements. Eur Radiol 2021; 31:5087-5095. [PMID: 33409772 DOI: 10.1007/s00330-020-07408-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Revised: 08/18/2020] [Accepted: 10/12/2020] [Indexed: 01/16/2023]
Abstract
OBJECTIVE Cardiac motion and aortic pulsatility can affect the image quality of 3D contrast-enhanced MR angiography (CE-MRA). The addition of ECG gating improves image quality; however, no studies have directly linked image quality improvements to clinically used measures. In this study, we directly compared diameter measurements in the same patient from ECG-gated to non-gated CE-MRA to evaluate the impact of ECG gating upon measurement reproducibility. METHODS Fifty-three patients, referred for thoracic aortic angiography, were enrolled and underwent both non-gated and ECG-gated CE-MRA. Two readers independently measured vessel diameter, image quality, and vessel sharpness at the sinus of Valsalva (SOV), sinotubular junction (STJX), ascending aorta (AAO), distal aortic arch (DLSA), and descending aorta (DAO). Measurement reliability and reproducibility were compared between methods. RESULTS Image quality with ECG gating was rated significantly higher at the SOV (3.2 ± 0.9 vs 1.2 ± 1.0, p < 0.0001), STJX (3.4 ± 0.7 vs 1.8 ± 1.0, p < 0.0001), AAO (3.5 ± 0.6 vs 1.7 ± 1.1 p < 0.0001), DLSA (4.0 ± 0.1 vs 3.6 ± 0.7, p = 0.006), and DAO (4.0 ± 0.1 vs 3.4 ± 0.9 p < 0.0001) than for non-gated studies. Bland-Altman analyses demonstrated that inter- and intra-observer variability was significantly smaller for ECG-gated MRA at the SOV and AAO. For the non-gated images at the SOV, the 95% limits of agreement for both inter- and intra-observer variability exceeded the growth-rate cutoff for surgical repair (0.5 cm). At the DAO, variability was similar between the two techniques. CONCLUSION ECG-gated CE-MRA resulted in improved reproducibility in aortic root and ascending aortic measurements. These data suggest that ECG-gated CE-MRA should be used for the serial assessment of the ascending thoracic aorta. KEY POINTS • ECG-gated CE-MRA improves the reproducibility and repeatability of measurements of the ascending aorta. • With non-gated CE-MRA, pulsatile motion in the proximal aorta results in significant variability in measurement reproducibility.
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14
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Markenroth Bloch K, Kording F, Töger J. Doppler ultrasound cardiac gating of intracranial flow at 7T. BMC Med Imaging 2020; 20:128. [PMID: 33297985 PMCID: PMC7724705 DOI: 10.1186/s12880-020-00523-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Accepted: 11/15/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Ultra-high field magnetic resonance imaging (MR) may be used to improve intracranial blood flow measurements. However, standard cardiac synchronization methods tend to fail at ultra-high field MR. Therefore, this study aims to investigate an alternative synchronization technique using Doppler ultrasound. METHODS Healthy subjects (n = 9) were examined with 7T MR. Flow was measured in the M1-branch of the middle cerebral artery (MCA) and in the cerebral aqueduct (CA) using through-plane phase contrast (2D flow). Flow in the circle of Willis was measured with three-dimensional, three-directional phase contrast (4D flow). Scans were gated with Doppler ultrasound (DUS) and electrocardiogram (ECG), and pulse oximetry data (POX) was collected simultaneously. False negative and false positive trigger events were counted for ECG, DUS and POX, and quantitative flow measures were compared. RESULTS There were fewer false positive triggers for DUS compared to ECG (5.3 ± 11 vs. 25 ± 31, p = 0.031), while no other measured parameters differed significantly. Net blood flow in M1 was similar between DUS and ECG for 2D flow (1.5 ± 0.39 vs. 1.6 ± 0.41, bias ± 1.96SD: - 0.021 ± 0.36) and 4D flow (1.8 ± 0.48 vs. 9 ± 0.59, bias ± 1.96SD: - 0.086 ± 0.57 ml). Net CSF flow per heart beat in the CA was also similar for DUS and ECG (3.6 ± 2.1 vs. 3.0 ± 5.8, bias ± 1.96SD: 0.61 ± 13.6 μl). CONCLUSION Gating with DUS produced fewer false trigger events than using ECG, with similar quantitative flow values. DUS gating is a promising technique for cardiac synchronization at 7T.
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Affiliation(s)
- Karin Markenroth Bloch
- The Swedish National 7T Facility, Lund University Bioimaging Center, Lund University, Klinikgatan 32, BMC D11, 22242, Lund, Sweden.
| | - Fabian Kording
- Department of Diagnostic and Interventional Radiology and Nuclear Medicine, University Medical Center Hamburg- Eppendorf, Hamburg, Germany.,Northh Medical GmbH, Röntgenstraße 24, 22335, Hamburg, Germany
| | - Johannes Töger
- Diagnostic Radiology, Department of Clinical Sciences Lund, Lund University and Skane University Hospital Lund, Lund, Sweden
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15
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Craven TP, Tsao CW, La Gerche A, Simonetti OP, Greenwood JP. Exercise cardiovascular magnetic resonance: development, current utility and future applications. J Cardiovasc Magn Reson 2020; 22:65. [PMID: 32907587 PMCID: PMC7488086 DOI: 10.1186/s12968-020-00652-w] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Accepted: 07/01/2020] [Indexed: 12/23/2022] Open
Abstract
Stress cardiac imaging is the current first line investigation for coronary artery disease diagnosis and decision making and an adjunctive tool in a range of non-ischaemic cardiovascular diseases. Exercise cardiovascular magnetic resonance (Ex-CMR) has developed over the past 25 years to combine the superior image qualities of CMR with the preferred method of exercise stress. Presently, numerous exercise methods exist, from performing stress on an adjacent CMR compatible treadmill to in-scanner exercise, most commonly on a supine cycle ergometer. Cardiac conditions studied by Ex-CMR are broad, commonly investigating ischaemic heart disease and congenital heart disease but extending to pulmonary hypertension and diabetic heart disease. This review presents an in-depth assessment of the various Ex-CMR stress methods and the varied pulse sequence approaches, including those specially designed for Ex-CMR. Current and future developments in image acquisition are highlighted, and will likely lead to a much greater clinical use of Ex-CMR across a range of cardiovascular conditions.
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Affiliation(s)
- Thomas P Craven
- Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK.
| | - Connie W Tsao
- Cardiovascular Division, Beth Israel Deaconess Medical Center, 330 Brookline Ave, RW-453, Boston, MA, 02215, USA
| | - Andre La Gerche
- Clinical Research Domain, Baker Heart and Diabetes Institute, Melbourne, Australia
- National Centre for Sports Cardiology, St Vincent's Hospital, Fitzroy, Australia
| | | | - John P Greenwood
- Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK
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16
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Wang H, Li H. Research on theoretical analysis of human capital of labor economics based on artificial intelligence. JOURNAL OF INTELLIGENT & FUZZY SYSTEMS 2019. [DOI: 10.3233/jifs-179127] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Affiliation(s)
- Haibo Wang
- Economics School, Dongbei University of Finance and Economics, Dalian, China
| | - Hua Li
- Economics School, Dongbei University of Finance and Economics, Dalian, China
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17
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Zhang C, Guan Y. Research on related technologies of vision target tracking based on discrete differential algorithm for deep learning. JOURNAL OF INTELLIGENT & FUZZY SYSTEMS 2019. [DOI: 10.3233/jifs-179128] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Affiliation(s)
- Changqi Zhang
- School of Communication and Information Engineering, Shanghai University, Shanghai, China
| | - Yepeng Guan
- School of Communication and Information Engineering, Shanghai University, Shanghai, China
- Key Laboratory of Advanced Displays and System Application, Ministry of Education, Shanghai, China
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18
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Lyu X, Gong E. Intelligent clustering analysis model for mining area mineral resource prediction. JOURNAL OF INTELLIGENT & FUZZY SYSTEMS 2019. [DOI: 10.3233/jifs-179110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Affiliation(s)
- Xiaodong Lyu
- School of Resources and Civil Engineering, Northeastern University, Shenyang, China
| | - Enpu Gong
- School of Resources and Civil Engineering, Northeastern University, Shenyang, China
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19
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Jaeschke SHF, Robson MD, Hess AT. Scattering matrix imaging pulse design for real-time respiration and cardiac motion monitoring. Magn Reson Med 2019; 82:2169-2177. [PMID: 31317579 PMCID: PMC6771869 DOI: 10.1002/mrm.27884] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Revised: 05/01/2019] [Accepted: 06/07/2019] [Indexed: 12/26/2022]
Abstract
Purpose The scattering matrix (S‐matrix) of a parallel transmit (pTx) coil is sensitive to physiological motion but requires additional monitoring RF pulses to be measured. In this work, we present and evaluate pTx RF pulse designs that simultaneously excite for imaging and measure the S‐matrix to generate real‐time motion signals without prolonging the image sequence. Theory and Methods Three pTx waveforms for measuring the S‐matrix were identified and superimposed onto the imaging excitation RF pulses: (1) time division multiplexing, (2) frequency division multiplexing, and (3) code division multiplexing. These 3 methods were evaluated in healthy volunteers for scattering sensitivity and image artefacts. The S‐matrix and real‐time motion signals were calculated on the image calculation environment of the MR scanner. Prospective cardiac triggers were identified in early systole as a high rate of change of the cardiac motion signal. Monitoring accuracy was compared against electrocardiogram or the imaged diaphragm position. Results All 3 monitoring approaches measure the S‐matrix during image excitation with quality correlated to input power. No image artefacts were observed for frequency multiplexing, and low energy artefacts were observed in the other methods. The accuracy of the achieved prospective cardiac gating was 15 ± 16 ms for breath hold and 24 ± 17 ms during free breathing. The diaphragm position prediction accuracy was 1.3 ± 0.9 mm. In all volunteers, good quality cine images were acquired for breath hold scans and dual gated CINEs were demonstrated. Conclusion The S‐matrix can be measured during image excitation to generate real‐time cardiac and respiratory motion signals for prospective gating. No artefacts are introduced when frequency division multiplexing is used.
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Affiliation(s)
- Sven H F Jaeschke
- Oxford Centre for Clinical Magnetic Resonance Research, Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Matthew D Robson
- Oxford Centre for Clinical Magnetic Resonance Research, Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom.,Perspectum Diagnostics, Oxford, United Kingdom
| | - Aaron T Hess
- Oxford Centre for Clinical Magnetic Resonance Research, Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom.,BHF Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
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20
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Di Sopra L, Piccini D, Coppo S, Stuber M, Yerly J. An automated approach to fully self‐gated free‐running cardiac and respiratory motion‐resolved 5D whole‐heart MRI. Magn Reson Med 2019; 82:2118-2132. [DOI: 10.1002/mrm.27898] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Revised: 06/13/2019] [Accepted: 06/14/2019] [Indexed: 11/10/2022]
Affiliation(s)
- Lorenzo Di Sopra
- Department of Diagnostic and Interventional Radiology Lausanne University Hospital Lausanne Switzerland
| | - Davide Piccini
- Department of Diagnostic and Interventional Radiology Lausanne University Hospital Lausanne Switzerland
- Advanced Clinical Imaging Technology Siemens Healthcare Lausanne Switzerland
| | - Simone Coppo
- Department of Diagnostic and Interventional Radiology Lausanne University Hospital Lausanne Switzerland
| | - Matthias Stuber
- Department of Diagnostic and Interventional Radiology Lausanne University Hospital Lausanne Switzerland
- Center for Biomedical Imaging Lausanne Switzerland
| | - Jérôme Yerly
- Department of Diagnostic and Interventional Radiology Lausanne University Hospital Lausanne Switzerland
- Center for Biomedical Imaging Lausanne Switzerland
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21
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Ling Z, Zengrui T, Metawa N. Data mining-based competency model of innovation and entrepreneurship. JOURNAL OF INTELLIGENT & FUZZY SYSTEMS 2019. [DOI: 10.3233/jifs-179061] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Affiliation(s)
- Zhao Ling
- The Glorious Sun School of Business and Management, Donghua University, ShangHai, China
| | - Tian Zengrui
- The Glorious Sun School of Business and Management, Donghua University, ShangHai, China
| | - Noura Metawa
- Anderson College of Business, Regis University, USA
- Faculty of Commerce, Mansoura University, Egypt
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22
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Erturk MA, Li X, Van de Moortele PF, Ugurbil K, Metzger GJ. Evolution of UHF Body Imaging in the Human Torso at 7T: Technology, Applications, and Future Directions. Top Magn Reson Imaging 2019; 28:101-124. [PMID: 31188271 PMCID: PMC6587233 DOI: 10.1097/rmr.0000000000000202] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/13/2023]
Abstract
The potential value of ultrahigh field (UHF) magnetic resonance imaging (MRI) and spectroscopy to biomedical research and in clinical applications drives the development of technologies to overcome its many challenges. The increased difficulties of imaging the human torso compared with the head include its overall size, the dimensions and location of its anatomic targets, the increased prevalence and magnitude of physiologic effects, the limited availability of tailored RF coils, and the necessary transmit chain hardware. Tackling these issues involves addressing notoriously inhomogeneous transmit B1 (B1) fields, limitations in peak B1, larger spatial variations of the static magnetic field B0, and patient safety issues related to implants and local RF power deposition. However, as research institutions and vendors continue to innovate, the potential gains are beginning to be realized. Solutions overcoming the unique challenges associated with imaging the human torso are reviewed as are current studies capitalizing on the benefits of UHF in several anatomies and applications. As the field progresses, strategies associated with the RF system architecture, calibration methods, RF pulse optimization, and power monitoring need to be further integrated into the MRI systems making what are currently complex processes more streamlined. Meanwhile, the UHF MRI community must seize the opportunity to build upon what have been so far proof of principle and feasibility studies and begin to further explore the true impact in both research and the clinic.
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Affiliation(s)
- M Arcan Erturk
- Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN
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23
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Hu C, Tokoglu F, Scheinost D, Qiu M, Shen X, Peters DC, Galiana G, Constable RT. Dynamic-flip-angle ECG-gating with nuisance signal regression improves resting-state BOLD functional connectivity mapping by reducing cardiogenic noise. Magn Reson Med 2019; 82:911-923. [PMID: 31016782 DOI: 10.1002/mrm.27775] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Revised: 03/20/2019] [Accepted: 03/24/2019] [Indexed: 11/07/2022]
Abstract
PURPOSE To investigate an ECG-gated dynamic-flip-angle BOLD sequence with improved robustness against cardiogenic noise in resting-state fMRI. METHODS ECG-gating minimizes the cardiogenic noise but introduces T1 -dependent signal variation, which is minimized by combination of a dynamic-flip-angle technique and retrospective nuisance signal regression (NSR) using signals of white matter, CSF, and global average. The technique was studied with simulations in a wide range of T1 and B1 fields and phantom imaging with pre-programmed TR variations. Resting-state fMRI of 20 healthy subjects was acquired with non-gated BOLD (NG), ECG-gated constant-flip-angle BOLD (GCFA), ECG-gated BOLD with retrospective T1 -correction (GRC), and ECG-gated dynamic-flip-angle BOLD (GDFA), all processed by the same NSR method. GDFA was compared to alternative methods over temporal SNR (tSNR), seed-based connectivity, and whole-brain voxelwise connectivity based on intrinsic connectivity distribution (ICD). A previous large-cohort data set (N = 100) was used as a connectivity gold standard. RESULTS Simulations and phantom imaging show substantial reduction of the T1 -dependent signal variation with GDFA alone, and further reduction with NSR. The resting-state study shows improved tSNR in the basal brain, comparing GDFA to NG, after both processed with NSR. Furthermore, GDFA significantly improved subcortical-subcortical and cortical-subcortical connectivity for several representative seeds and significantly improved ICD in the brainstem, thalamus, striatum, and prefrontal cortex, compared to the other 3 approaches. CONCLUSION GDFA with NSR improves mapping of the resting-state functional connectivity of the basal-brain regions by reducing cardiogenic noise.
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Affiliation(s)
- Chenxi Hu
- Department of Radiology and Biomedical Imaging, Yale School of Medicine, Yale University, New Haven, Conneticut
| | - Fuyuze Tokoglu
- Department of Radiology and Biomedical Imaging, Yale School of Medicine, Yale University, New Haven, Conneticut
| | - Dustin Scheinost
- Department of Radiology and Biomedical Imaging, Yale School of Medicine, Yale University, New Haven, Conneticut
| | - Maolin Qiu
- Department of Radiology and Biomedical Imaging, Yale School of Medicine, Yale University, New Haven, Conneticut
| | - Xilin Shen
- Department of Radiology and Biomedical Imaging, Yale School of Medicine, Yale University, New Haven, Conneticut
| | - Dana C Peters
- Department of Radiology and Biomedical Imaging, Yale School of Medicine, Yale University, New Haven, Conneticut
| | - Gigi Galiana
- Department of Radiology and Biomedical Imaging, Yale School of Medicine, Yale University, New Haven, Conneticut
| | - R Todd Constable
- Department of Radiology and Biomedical Imaging, Yale School of Medicine, Yale University, New Haven, Conneticut
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24
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Guo L, Herzka DA. Sorted Golden-step phase encoding: an improved Golden-step imaging technique for cardiac and respiratory self-gated cine cardiovascular magnetic resonance imaging. J Cardiovasc Magn Reson 2019; 21:23. [PMID: 30999911 PMCID: PMC6472023 DOI: 10.1186/s12968-019-0533-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2018] [Accepted: 03/19/2019] [Indexed: 11/17/2022] Open
Abstract
BACKGROUND Numerous self-gated cardiac imaging techniques have been reported in the literature. Most can track either cardiac or respiratory motion, and many incur some overhead to imaging data acquisition. We previously described a Cartesian cine imaging technique, pseudo-projection motion tracking with golden-step phase encoding, capable of tracking both cardiac and respiratory motion at no cost to imaging data acquisition. In this work, we describe improvements to the technique by dramatically reducing its vulnerability to eddy current and flow artifacts and demonstrating its effectiveness in expanded cardiovascular applications. METHODS As with our previous golden-step technique, the Cartesian phase encodes over time were arranged based on the integer golden step, and readouts near ky = 0 (pseudo-projections) were used to derive motion. In this work, however, the readouts were divided into equal and consecutive temporal segments, within which the readouts were sorted according to ky. The sorting reduces the phase encode jump between consecutive readouts while maintaining the pseudo-randomness of ky to sample both cardiac and respiratory motion without comprising the ability to retrospectively set the temporal resolution of the original technique. On human volunteers, free-breathing, electrocardiographic (ECG)-free cine scans were acquired for all slices of the short axis stack and the 4-chamber view of the long axis. Retrospectively, cardiac motion and respiratory motion were automatically extracted from the pseudo-projections to guide cine reconstruction. The resultant image quality in terms of sharpness and cardiac functional metrics was compared against breath-hold ECG-gated reference cines. RESULTS With sorting, motion tracking of both cardiac and respiratory motion was effective for all slices orientations imaged, and artifact occurrence due to eddy current and flow was efficiently eliminated. The image sharpness derived from the self-gated cines was found to be comparable to the reference cines (mean difference less than 0.05 mm- 1 for short-axis images and 0.075 mm- 1 for long-axis images), and the functional metrics (mean difference < 4 ml) were found not to be statistically different from those from the reference. CONCLUSIONS This technique dramatically reduced the eddy current and flow artifacts while preserving the ability of cost-free motion tracking and the flexibility of choosing arbitrary navigator zone width, number of cardiac phases, and duration of scanning. With the restriction of the artifacts removed, the Cartesian golden-step cine imaging can now be applied to cardiac imaging slices of more diverse orientation and anatomy at greater reliability.
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Affiliation(s)
- Liheng Guo
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, 720 Rutland Ave, Suite 726 Ross Building, Baltimore, MD 21205 USA
| | - Daniel A. Herzka
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, 720 Rutland Ave, Suite 726 Ross Building, Baltimore, MD 21205 USA
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25
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Yu Z, Zhao T, Assländer J, Lattanzi R, Sodickson DK, Cloos MA. Exploring the sensitivity of magnetic resonance fingerprinting to motion. Magn Reson Imaging 2018; 54:241-248. [PMID: 30193953 PMCID: PMC6215476 DOI: 10.1016/j.mri.2018.09.002] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Revised: 09/01/2018] [Accepted: 09/04/2018] [Indexed: 11/19/2022]
Abstract
PURPOSE To explore the motion sensitivity of magnetic resonance fingerprinting (MRF), we performed experiments with different types of motion at various time intervals during multiple scans. Additionally, we investigated the possibility to correct the motion artifacts based on redundancy in MRF data. METHODS A radial version of the FISP-MRF sequence was used to acquire one transverse slice through the brain. Three subjects were instructed to move in different patterns (in-plane rotation, through-plane wiggle, complex movements, adjust head position, and pretend itch) during different time intervals. The potential to correct motion artifacts in MRF by removing motion-corrupted data points from the fingerprints and dictionary was evaluated. RESULTS Morphological structures were well preserved in multi-parametric maps despite subject motion. Although the bulk T1 values were not significantly affected by motion, fine structures were blurred when in-plane motion was present during the first part of the scan. On the other hand, T2 values showed a considerable deviation from the motion-free results, especially when through-plane motion was present in the middle of the scan (-44% on average). Explicitly removing the motion-corrupted data from the scan partially restored the T2 values (-10% on average). CONCLUSION Our experimental results showed that different kinds of motion have distinct effects on the precision and effective resolution of the parametric maps measured with MRF. Although MRF-based acquisitions can be relatively robust to motion effects occurring at the beginning or end of the sequence, relying on redundancy in the data alone is not sufficient to assure the accuracy of the multi-parametric maps in all cases.
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Affiliation(s)
- Zidan Yu
- Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, NY, USA; Center for Advanced Imaging Innovation and Research (CAI(2)R), Department of Radiology, New York University School of Medicine, New York, NY, USA; The Sackler Institute of Graduate Biomedical Sciences, New York University School of Medicine, New York, NY, USA.
| | - Tiejun Zhao
- Center for Advanced Imaging Innovation and Research (CAI(2)R), Department of Radiology, New York University School of Medicine, New York, NY, USA; Siemens Medical Solutions USA Inc., 40 Liberty Boulevard, Malvern, PA 19355, USA
| | - Jakob Assländer
- Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, NY, USA; Center for Advanced Imaging Innovation and Research (CAI(2)R), Department of Radiology, New York University School of Medicine, New York, NY, USA
| | - Riccardo Lattanzi
- Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, NY, USA; Center for Advanced Imaging Innovation and Research (CAI(2)R), Department of Radiology, New York University School of Medicine, New York, NY, USA; The Sackler Institute of Graduate Biomedical Sciences, New York University School of Medicine, New York, NY, USA
| | - Daniel K Sodickson
- Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, NY, USA; Center for Advanced Imaging Innovation and Research (CAI(2)R), Department of Radiology, New York University School of Medicine, New York, NY, USA; The Sackler Institute of Graduate Biomedical Sciences, New York University School of Medicine, New York, NY, USA
| | - Martijn A Cloos
- Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, NY, USA; Center for Advanced Imaging Innovation and Research (CAI(2)R), Department of Radiology, New York University School of Medicine, New York, NY, USA; The Sackler Institute of Graduate Biomedical Sciences, New York University School of Medicine, New York, NY, USA
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26
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Zhang X, Xie G, Lu N, Zhu Y, Wei Z, Su S, Shi C, Yan F, Liu X, Qiu B, Fan Z. 3D self-gated cardiac cine imaging at 3 Tesla using stack-of-stars bSSFP with tiny golden angles and compressed sensing. Magn Reson Med 2018; 81:3234-3244. [PMID: 30474151 DOI: 10.1002/mrm.27612] [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: 05/12/2018] [Revised: 10/25/2018] [Accepted: 10/29/2018] [Indexed: 12/25/2022]
Abstract
PURPOSE To develop and evaluate an accelerated 3D self-gated cardiac cine imaging technique at 3 Tesla without the use of external electrocardiogram triggering or respiratory gating. METHODS A 3D stack-of-stars balanced steady-state free precession sequence with a tiny golden angle sampling scheme was developed to reduced eddy current effect-related artefacts at 3 Tesla. Respiratory and cardiac motion were derived from a central 5-point self-gating signal extraction approach. The data acquired around the end-expiration phases were then sorted into individual cardiac bins and used for reconstruction with compressed sensing. To evaluate the performance of the proposed method, image quality (1: the best; 4: the worst) was quantitatively compared using both the proposed method and the conventional 3D golden-angle self-gated method. Linear regression and Bland-Altman analysis were used to assess the functional measurements agreement between the proposed method and the routine 2D breath-hold multi-slice technique. RESULTS Compared to the conventional 3D golden-angle self-gated method, the proposed method yielded images with much less streaking artifact and higher myocardium edge sharpness (0.50 ± 0.06 vs. 0.45 ± 0.05, P = 0.004). The proposed method provided an inferior image quality score to the routine 2D technique (2.13 ± 0.35 vs. 1.38 ± 0.52, P = 0.063) but a superior one to the conventional self-gated method (2.13 ± 0.35 vs. 3.13 ± 0.64, P = 0.031). Left ventricular functional measurements between the proposed method and routine 2D technique were all well in agreement. CONCLUSION This study presents a novel self-gating approach to realize rapid 3D cardiac cine imaging at 3 Tesla.
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Affiliation(s)
- Xiaoyong Zhang
- Centers for Biomedical Engineering, University of Science and Technology of China, Hefei, People's Republic of China.,MR Collaborations NE Asia, Siemens Healthcare, Shenzhen, People's Republic of China
| | - Guoxi Xie
- Paul C. Lauterber Research Center for Biomedical Imaging, Institute of Biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, People's Republic of China.,Guangzhou Medical University, Guangzhou, People's Republic of China
| | - Na Lu
- Guangzhou Medical University, Guangzhou, People's Republic of China
| | - Yanchun Zhu
- Paul C. Lauterber Research Center for Biomedical Imaging, Institute of Biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, People's Republic of China
| | - Zijun Wei
- Paul C. Lauterber Research Center for Biomedical Imaging, Institute of Biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, People's Republic of China
| | - Shi Su
- Paul C. Lauterber Research Center for Biomedical Imaging, Institute of Biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, People's Republic of China
| | - Caiyun Shi
- Paul C. Lauterber Research Center for Biomedical Imaging, Institute of Biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, People's Republic of China
| | - Fei Yan
- Paul C. Lauterber Research Center for Biomedical Imaging, Institute of Biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, People's Republic of China
| | - Xin Liu
- Paul C. Lauterber Research Center for Biomedical Imaging, Institute of Biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, People's Republic of China
| | - Bensheng Qiu
- Centers for Biomedical Engineering, University of Science and Technology of China, Hefei, People's Republic of China
| | - Zhaoyang Fan
- Biomedical Imaging Research Institute, Cedars-Sinai Medical Center, Los Angeles, California.,Departments of Medicine and Bioengineering, University of California, Los Angeles, California
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Jaeschke SH, Robson MD, Hess AT. Cardiac gating using scattering of an 8-channel parallel transmit coil at 7T. Magn Reson Med 2018; 80:633-640. [PMID: 29230860 PMCID: PMC5947608 DOI: 10.1002/mrm.27038] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Revised: 10/27/2017] [Accepted: 11/17/2017] [Indexed: 12/24/2022]
Abstract
PURPOSE To establish a cardiac signal from scattering matrix or scattering coefficient measurements made on a 7T 8-channel parallel transmit (pTx) system, and to evaluate its use for cardiac gating. METHODS Measurements of the scattering matrix and scattering coefficients were acquired using a monitoring pulse sequence and during a standard cine acquisition, respectively. Postprocessing used an independent component analysis and gating feature identification. The effect of the phase of the excitation radiofrequency (RF) field ( B1+ shim) on the cardiac signal was simulated for multiple B1+ shim configurations, and cine images were reconstructed from both the scattering coefficients and electrocardiogram (ECG). RESULTS The cardiac motion signal was successfully identified in all subjects with a mean signal-to-noise ratio of 33.1 and 5.7 using the scattering matrix and scattering coefficient measurements, respectively. The dominant gating feature in the cardiac signal was a peak aligned with end-systole that occurred on average at 311 and 391 ms after the ECG trigger, with a mean standard deviation of 13.4 and 18.1 ms relative to ECG when using the scattering matrix and scattering coefficients measurements, respectively. The scattering coefficients showed a dependence on B1+ shim with some shim configurations not showing any cardiac signal. Cine images were successfully reconstructed using the scattering coefficients with minimal differences compared to those using ECG. CONCLUSION We have shown that the scattering of a pTx RF coil can be used to estimate a cardiac signal, and that scattering matrix and coefficients can be used to cardiac gate MRI acquisitions with the scattering matrix providing a superior cardiac signal. Magn Reson Med 80:633-640, 2018. © 2017 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
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Affiliation(s)
- Sven H.F. Jaeschke
- University of Oxford Centre for Clinical Magnetic Resonance Research, John Radcliffe HospitalOxfordUnited Kingdom
| | - Matthew D. Robson
- University of Oxford Centre for Clinical Magnetic Resonance Research, John Radcliffe HospitalOxfordUnited Kingdom
| | - Aaron T. Hess
- University of Oxford Centre for Clinical Magnetic Resonance Research, John Radcliffe HospitalOxfordUnited Kingdom
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Abstract
This study aims to investigate a set of electrocardiogram (ECG) electrode lead locations to improve the quality of four-lead ECG signals acquired during magnetic resonance imaging (MRI). This was achieved by identifying electrode placements that minimized the amount of induced magnetohydrodynamic voltages (VMHD) in the ECG signals. Reducing VMHD can improve the accuracy of QRS complex detection in ECG as well as heartbeat synchronization between MRI and ECG during the acquisition of cardiac cine. A vector model based on thoracic geometry was developed to predict induced VMHD and to optimize four-lead ECG electrode placement for the purposes of improved MRI gating. Four human subjects were recruited for vector model establishment (Group 1), and five human subjects were recruited for validation of VMHD reduction in the proposed four-lead ECG (Group 2). The vector model was established using 12-lead ECG data recorded from Group 1 of four healthy subjects at 3 Tesla, and a gradient descent optimization routine was utilized to predict optimal four-lead ECG placement based on VMHD vector alignment. The optimized four-lead ECG was then validated in Group 2 of five healthy subjects by comparing the standard and proposed lead placements. A 43.41% reduction in VMHD was observed in ECGs using the proposed electrode placement, and the QRS complex was preserved. A VMHD-minimized electrode placement for four-lead ECG gating was presented and shown to reduce induced magnetohydrodynamic (MHD) signals, potentially allowing for improved cardiac MRI physiological monitoring.
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Elinoff JM, Agarwal R, Barnett CF, Benza RL, Cuttica MJ, Gharib AM, Gray MP, Hassoun PM, Hemnes AR, Humbert M, Kolb TM, Lahm T, Leopold JA, Mathai SC, McLaughlin VV, Preston IR, Rosenzweig EB, Shlobin OA, Steen VD, Zamanian RT, Solomon MA. Challenges in Pulmonary Hypertension: Controversies in Treating the Tip of the Iceberg. A Joint National Institutes of Health Clinical Center and Pulmonary Hypertension Association Symposium Report. Am J Respir Crit Care Med 2018; 198:166-174. [PMID: 29425462 PMCID: PMC6058980 DOI: 10.1164/rccm.201710-2093pp] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Accepted: 02/09/2018] [Indexed: 01/13/2023] Open
Affiliation(s)
| | - Richa Agarwal
- Division of Cardiovascular Disease, Department of Medicine, Allegheny General Hospital, Pittsburgh, Pennsylvania
| | | | - Raymond L. Benza
- Division of Cardiovascular Disease, Department of Medicine, Allegheny General Hospital, Pittsburgh, Pennsylvania
| | - Michael J. Cuttica
- Division of Pulmonary and Critical Care Medicine, Northwestern University Feinberg School of Medicine, Chicago, Illinois
| | - Ahmed M. Gharib
- National Institute of Diabetes, Digestive, and Kidney Diseases, and
| | | | - Paul M. Hassoun
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University, Baltimore, Maryland
| | - Anna R. Hemnes
- Division of Allergy, Pulmonary and Critical Care Medicine, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Marc Humbert
- Service de Pneumologie, Hôpital Bicêtre (Assistance Publique–Hôpitaux de Paris), Institut National de la Santé et de la Recherche Médicale U999, University Paris–Sud, Université Paris-Saclay, Le Kremlin-Bicêtre, France
| | - Todd M. Kolb
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University, Baltimore, Maryland
| | - Tim Lahm
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Indiana University, Indianapolis, Indiana
- Richard L. Roudebush VA Medical Center, Indianapolis, Indiana
| | - Jane A. Leopold
- Division of Cardiovascular Medicine, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts
| | - Stephen C. Mathai
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University, Baltimore, Maryland
| | - Vallerie V. McLaughlin
- Division of Cardiology, Department of Medicine, University of Michigan, Ann Arbor, Michigan
| | - Ioana R. Preston
- Department of Medicine, Tufts Medical Center, Tufts University School of Medicine, Boston, Massachusetts
| | | | - Oksana A. Shlobin
- Pulmonary Vascular Disease Program, Inova Fairfax Hospital, Falls Church, Virginia
| | - Virginia D. Steen
- Rheumatology Division, Department of Medicine, Georgetown University, Washington, DC; and
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Intra-MRI Extraction of Diagnostic Electrocardiograms Using Carotidal Magnetohydrodynamic Voltages. J Imaging 2018. [DOI: 10.3390/jimaging4050066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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31
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Iyama Y, Nakaura T, Nagayama Y, Oda S, Utsunomiya D, Kidoh M, Yuki H, Hirata K, Namimoto T, Kitajima M, Morita K, Funama Y, Takemura A, Tokuyasu S, Okuaki T, Yamashita Y. Comparison between multi-shot gradient echo EPI and balanced SSFP in unenhanced 3T MRA of thoracic aorta in healthy volunteers. Eur J Radiol 2017; 96:85-90. [PMID: 29103481 DOI: 10.1016/j.ejrad.2017.09.012] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Revised: 06/11/2017] [Accepted: 09/18/2017] [Indexed: 11/17/2022]
Abstract
PURPOSE The purpose of this study was to compare scan time and image quality between magnetic resonance angiography (MRA) of the thoracic aorta using a multi-shot gradient echo planar imaging (MSG-EPI) and MRA using balanced steady-state free precession (b-SSFP). MATERIALS AND METHODS Healthy volunteers (n=17) underwent unenhanced thoracic aorta MRA using balanced steady-state free precession (b-SSFP) and MSG-EPI sequences on a 3T MRI. The acquisition time, total scan time, signal-to-noise ratio (SNR) of the thoracic aorta, and the coefficient of variation (CV) of thoracic aorta were compared with paired t-tests. Two radiologists independently recorded the images' contrast, noise, sharpness, artifacts, and overall quality on a 4-point scale. RESULTS The acquisition time was 36.2% shorter for MSG-EPI than b-SSFP (115.5±14.4 vs 181.0±14.9s, p<0.01). The total scan time was 40.4% shorter for MSG-EPI than b-SSFP (272±78 vs 456±144s, p<0.01). There was no significant difference in mean SNR between MSG-EPI and b-SSFP scans (17.3±3.6 vs 15.2±4.3, p=0.08). The CV was significantly lower for MSG-EPI than b-SSFP (0.2±0.1 vs. 0.5±0.2, p<0.01). All qualitative scores except for image noise were significantly higher in MSG-EPI than b-SSFP scans (p<0.05). CONCLUSION The MSG-EPI sequence is a promising technique for shortening scan time and yielding more homogenous image quality in MRA of thoracic aorta on 3T scanners compared with the b-SSFP.
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Affiliation(s)
- Yuji Iyama
- Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University, Honjo 1-1-1, Kumamoto, Kumamoto 860-8556, Japan.
| | - Takeshi Nakaura
- Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University, Honjo 1-1-1, Kumamoto, Kumamoto 860-8556, Japan.
| | - Yasunori Nagayama
- Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University, Honjo 1-1-1, Kumamoto, Kumamoto 860-8556, Japan.
| | - Seitaro Oda
- Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University, Honjo 1-1-1, Kumamoto, Kumamoto 860-8556, Japan.
| | - Daisuke Utsunomiya
- Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University, Honjo 1-1-1, Kumamoto, Kumamoto 860-8556, Japan.
| | - Masafumi Kidoh
- Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University, Honjo 1-1-1, Kumamoto, Kumamoto 860-8556, Japan.
| | - Hideaki Yuki
- Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University, Honjo 1-1-1, Kumamoto, Kumamoto 860-8556, Japan.
| | - Kenichiro Hirata
- Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University, Honjo 1-1-1, Kumamoto, Kumamoto 860-8556, Japan.
| | - Tomohiro Namimoto
- Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University, Honjo 1-1-1, Kumamoto, Kumamoto 860-8556, Japan.
| | - Mika Kitajima
- Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University, Honjo 1-1-1, Kumamoto, Kumamoto 860-8556, Japan.
| | - Kosuke Morita
- Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University, Honjo 1-1-1, Kumamoto, Kumamoto 860-8556, Japan.
| | - Yoshinori Funama
- Department of Medical Physics, Faculty of Life Sciences, Kumamoto University, Kuhonji 4-24-1, Kumamoto, Kumamoto 860-8556, Japan.
| | - Atsushi Takemura
- Philips Healthcare Japan, 13-37 Kohnan 2-chome, Minato-ku, Tokyo 108-8507, Japan.
| | - Shinichi Tokuyasu
- Philips Healthcare Japan, 13-37 Kohnan 2-chome, Minato-ku, Tokyo 108-8507, Japan.
| | - Tomoyuki Okuaki
- Philips Healthcare Japan, 13-37 Kohnan 2-chome, Minato-ku, Tokyo 108-8507, Japan.
| | - Yasuyuki Yamashita
- Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University, Honjo 1-1-1, Kumamoto, Kumamoto 860-8556, Japan.
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Magnetohydrodynamic Voltage Recorder for Comparing Peripheral Blood Flow. Ann Biomed Eng 2017. [DOI: 10.1007/s10439-017-1878-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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33
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Iyama Y, Nakaura T, Nagayama Y, Oda S, Utsunomiya D, Kidoh M, Yuki H, Hirata K, Namimoto T, Kitajima M, Morita K, Funama Y, Takemura A, Okuaki T, Yamashita Y. Single-Breath-Hold Whole-heart Unenhanced Coronary MRA Using Multi-shot Gradient Echo EPI at 3T: Comparison with Free-breathing Turbo-field-echo Coronary MRA on Healthy Volunteers. Magn Reson Med Sci 2017; 17:161-167. [PMID: 28652524 PMCID: PMC5891342 DOI: 10.2463/mrms.mp.2017-0037] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Purpose: We investigated the feasibility of single breath hold unenhanced coronary MRA using multi-shot gradient echo planar imaging (MSG-EPI) on a 3T-scanner. Methods: Fourteen volunteers underwent single breath hold coronary MRA with a MSG-EPI and free-breathing turbo field echo (TFE) coronary MRA at 3T. The acquisition time, signal to noise ratio (SNR), and the contrast of the sequences were compared with the paired t-test. Readers evaluated the image contrast, noise, sharpness, artifacts, and the overall image quality. Results: The acquisition time was 88.1% shorter for MSG-EPI than TFE (24.7 ± 2.5 vs 206.4 ± 23.1 sec, P < 0.01). The SNR was significantly higher on MSG-EPI than TFE scans (P < 0.01). There was no significant difference in the contrast on MSG-EPI and TFE scans (1.8 ± 0.3 vs 1.9 ± 0.3, P = 0.24). There was no significant difference in image contrast, image sharpness, and overall image quality between two scan techniques. The score of image noise and artifact were significantly higher on MSG-EPI than TFE scans (P < 0.05). Conclusion: The single breath hold MSG-EPI sequence is a promising technique for shortening the scan time and for preserving the image quality of unenhanced whole heart coronary MRA on a 3T scanner.
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Affiliation(s)
- Yuji Iyama
- Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University
| | - Takeshi Nakaura
- Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University
| | - Yasunori Nagayama
- Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University
| | - Seitaro Oda
- Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University
| | - Daisuke Utsunomiya
- Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University
| | - Masafumi Kidoh
- Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University
| | - Hideaki Yuki
- Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University
| | - Kenichiro Hirata
- Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University
| | - Tomohiro Namimoto
- Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University
| | - Mika Kitajima
- Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University
| | - Kosuke Morita
- Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University
| | - Yoshinori Funama
- Department of Medical Physics, Faculty of Life Sciences, Kumamoto University
| | | | | | - Yasuyuki Yamashita
- Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University
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Adaptive step size LMS improves ECG detection during MRI at 1.5 and 3 T. MAGNETIC RESONANCE MATERIALS IN PHYSICS BIOLOGY AND MEDICINE 2017. [PMID: 28631204 DOI: 10.1007/s10334-017-0638-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
OBJECTIVE We describe a new real-time filter to reduce artefacts on electrocardiogram (ECG) due to magnetic field gradients during MRI. The proposed filter is a least mean square (LMS) filter able to continuously adapt its step size according to the gradient signal of the ongoing MRI acquisition. MATERIALS AND METHODS We implemented this filter and compared it, within two databases (at 1.5 and 3 T) with over 6000 QRS complexes, to five real-time filtering strategies (no filter, low pass filter, standard LMS, and two other filters optimized within the databases: optimized LMS, and optimized Kalman filter). RESULTS The energy of the remaining noise was significantly reduced (26 vs. 68%, p < 0.001) with the new filter vs. standard LMS. The detection error of our ventricular complex (QRS) detector was: 11% with our method vs. 25% with raw ECG, 35% with low pass filter, 17% with standard LMS, 12% with optimized Kalman filter, and 11% with optimized LMS filter. CONCLUSION The adaptive step size LMS improves ECG denoising during MRI. QRS detection has the same F1 score with this filter than with filters optimized within the database.
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Kim D, Seo H, Cho J, Kwon K, Han Y, Park H. Non-contrast-enhanced peripheral MR angiography using velocity-selective excitation. Magn Reson Med 2017; 79:779-788. [PMID: 28580695 DOI: 10.1002/mrm.26732] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2016] [Revised: 04/01/2017] [Accepted: 04/02/2017] [Indexed: 02/02/2023]
Abstract
PURPOSE To develop a new non-contrast-enhanced peripheral MR angiography that provides a high contrast angiogram without using electrocardiography triggering and saturation radiofrequency pulses. METHODS A velocity-selective excitation technique is used in conjunction with the golden-angle radial sampling scheme. The signal amplitude varies according to the velocity of the flow by the velocity-selective excitation technique. Because the arterial blood velocity varies depending on the cardiac phase, the acquired data can be classified into systolic and diastolic phase based on the signal amplitude of the artery. Two images are then reconstructed from the systolic and diastolic phase data, respectively, and an image reflecting the differences between the two images is obtained to eliminate background and vein signals. The performance of the proposed method was compared with the quiescent-interval single shot (QISS) in eight healthy subjects and an elderly subject. RESULTS The proposed method generated fewer residual venous and background signals than the QISS. Furthermore, the maximum intensity projection images, the relative contrast, and the apparent contrast-to-noise ratio results showed that the proposed method produced a better contrast than the QISS. CONCLUSIONS The proposed non-contrast-enhanced peripheral MR angiography technique can provide a high contrast angiogram without the use of electrocardiography triggering and saturation radiofrequency pulses. Magn Reson Med 79:779-788, 2018. © 2017 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Dongchan Kim
- College of Medicine, Gachon University, Hambakmoero 191, Yeonsu-gu, Incheon, Republic of Korea
| | - Hyunseok Seo
- Department of Electrical Engineering, Korea Advanced Institute of Science and Technology, Guseong-dong, Yuseong-gu, Daejeon, Republic of Korea
| | - Jaejin Cho
- Department of Electrical Engineering, Korea Advanced Institute of Science and Technology, Guseong-dong, Yuseong-gu, Daejeon, Republic of Korea
| | - Kinam Kwon
- Department of Electrical Engineering, Korea Advanced Institute of Science and Technology, Guseong-dong, Yuseong-gu, Daejeon, Republic of Korea
| | - Yeji Han
- Department of Biomedical Engineering, College of Health Sciences, Gachon University, Hambakmoero 191, Yeonsu-gu, Incheon, Republic of Korea
| | - HyunWook Park
- Department of Electrical Engineering, Korea Advanced Institute of Science and Technology, Guseong-dong, Yuseong-gu, Daejeon, Republic of Korea
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Coronary atherosclerosis and dilation in hyper IgE syndrome patients: Depiction by magnetic resonance vessel wall imaging and pathological correlation. Atherosclerosis 2017; 258:20-25. [PMID: 28167354 DOI: 10.1016/j.atherosclerosis.2017.01.022] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Revised: 12/31/2016] [Accepted: 01/18/2017] [Indexed: 01/19/2023]
Abstract
BACKGROUND AND AIMS Autosomal dominant hyper-IgE (AD-HIES) is a primary immunodeficiency caused by mutations in STAT3. Elevated levels of IgE, an ineffective immune response, connective tissue abnormalities, and coronary arterial dilation and tortuosity characterize AD-HIES. To date, coronary artery evaluation in AD-HIES patients has been limited to lumenography measurements. Direct in vivo coronary vessel wall (VW) imaging may allow for better interrogation of coronary vessel abnormalities. The goal of this prospective study was to evaluate the coronary VW of AD-HIES patients using Magnetic Resonance Imaging (MRI) and histology. VW image findings were compared in healthy subjects and subjects with coronary atherosclerotic disease (CAD). METHODS A total of 28 subjects (10 with AD-HIES, 8 healthy, 10 with CAD) were studied by coronary VW MRI imaging. Additionally, a post-mortem coronary artery from one VW imaged AD-HIES patient was examined. RESULTS Coronary VW in AD-HIES was thicker than in healthy controls but not significantly different from VW thickness in CAD subjects. AD-HIES coronaries showed increased VW area compared to healthy controls and CAD subjects. On histology, the AD-HIES coronary artery had findings consistent with atherosclerotic plaque, but had minimal luminal narrowing, deficient adventitia thickening and absence of both internal and external elastic laminae. CONCLUSIONS This is the first study to demonstrate subclinical coronary atherosclerosis in AD-HIES patients on VW imaging by MRI. Histologic evaluation confirmed the presence of atherosclerosis with lack of supportive adventitial thickening and elastic components. These findings suggest mechanisms for coronary dilation in AD-HIES and thereby help direct clinical management.
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Spicher N, Kukuk M, Maderwald S, Ladd ME. Initial evaluation of prospective cardiac triggering using photoplethysmography signals recorded with a video camera compared to pulse oximetry and electrocardiography at 7T MRI. Biomed Eng Online 2016; 15:126. [PMID: 27881126 PMCID: PMC5122166 DOI: 10.1186/s12938-016-0245-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Accepted: 11/10/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Accurate synchronization between magnetic resonance imaging data acquisition and a subject's cardiac activity ("triggering") is essential for reducing image artifacts but conventional, contact-based methods for this task are limited by several factors, including preparation time, patient inconvenience, and susceptibility to signal degradation. The purpose of this work is to evaluate the performance of a new contact-free triggering method developed with the aim to eventually replace conventional methods in non-cardiac imaging applications. In this study, the method's performance is evaluated in the context of 7 Tesla non-enhanced angiography of the lower extremities. METHODS Our main contribution is a basic algorithm capable of estimating in real-time the phase of the cardiac cycle from reflection photoplethysmography signals obtained from skin color variations of the forehead recorded with a video camera. Instead of finding the algorithm's parameters heuristically, they were optimized using videos of the forehead as well as electrocardiography and pulse oximetry signals that were recorded from eight healthy volunteers in and outside the scanner, with and without active radio frequency and gradient coils. Based on the video characteristics, synthetic signals were generated and the "best available" values of an objective function were determined using mathematical optimization. The performance of the proposed method with optimized algorithm parameters was evaluated by applying it to the recorded videos and comparing the computed triggers to those of contact-based methods. Additionally, the method was evaluated by using its triggers for acquiring images from a healthy volunteer and comparing the result to images obtained using pulse oximetry triggering. RESULTS During evaluation of the videos recorded inside the bore with active radio frequency and gradient coils, the pulse oximeter triggers were labeled in 62.5% as "potentially usable" for cardiac triggering, the electrocardiography triggers in 12.5%, and the proposed method's triggers in 62.5%. Evaluation of the angiography images demonstrated that under appropriate conditions the method is feasible to produce an image quality comparable to pulse oximetry. CONCLUSION We conclude that cardiac triggering using the proposed method is technically feasible. However, for improved reliability the signal-to-noise ratio of the videos will have to be addressed by either replacing the camera sensor, improving the illumination, or by use of additional signal filtering techniques.
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Affiliation(s)
- Nicolai Spicher
- Department of Computer Science, University of Applied Sciences and Arts Dortmund, Emil-Figge-Str. 42, 44227, Dortmund, Germany.
| | - Markus Kukuk
- Department of Computer Science, University of Applied Sciences and Arts Dortmund, Emil-Figge-Str. 42, 44227, Dortmund, Germany
| | - Stefan Maderwald
- Erwin L. Hahn Institute for Magnetic Resonance Imaging, University Duisburg-Essen, Kokereiallee 7, 45141, Essen, Germany
| | - Mark E Ladd
- Erwin L. Hahn Institute for Magnetic Resonance Imaging, University Duisburg-Essen, Kokereiallee 7, 45141, Essen, Germany.,Division of Medical Physics in Radiology, German Cancer Research Center, Im Neuenheimer Feld 280, 69120, Heidelberg, Germany
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Schmidt M, Krug JW, Rose G. Real-time QRS detection using integrated variance for ECG gated cardiac MRI. CURRENT DIRECTIONS IN BIOMEDICAL ENGINEERING 2016. [DOI: 10.1515/cdbme-2016-0057] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Abstract
During magnetic resonance imaging (MRI), a patient’s vital signs are required for different purposes. In cardiac MRI (CMR), an electrocardiogram (ECG) of the patient is required for triggering the image acquisition process. However, a reliable QRS detection of an ECG signal acquired inside an MRI scanner is a challenging task due to the magnetohydrodynamic (MHD) effect which interferes with the ECG. The aim of this work was to develop a reliable QRS detector usable inside the MRI which also fulfills the standards for medical devices (IEC 60601-2-27). Therefore, a novel real-time QRS detector based on integrated variance measurements is presented. The algorithm was trained on ANSI/AAMI EC13 test waveforms and was then applied to two databases with 12-lead ECG signals recorded inside and outside an MRI scanner. Reliable results for both databases were achieved for the ECG signals recorded inside (DBMRI: sensitivity Se = 99.94%, positive predictive value +P = 99.84%) and outside (DBInCarT: Se = 99.29%, +P = 99.72%) the MRI. Due to the accurate R-peak detection in real-time this can be used for monitoring and triggering in MRI exams.
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Affiliation(s)
- Marcus Schmidt
- Department of Medical Engineering, Otto-von-Guericke-University of Magdeburg, Germany
| | - Johannes W. Krug
- Department of Medical Engineering, Otto-von-Guericke-University of Magdeburg, Germany
| | - Georg Rose
- Department of Medical Engineering, Otto-von-Guericke-University of Magdeburg, Germany
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Stäb D, Roessler J, O'Brien K, Hamilton-Craig C, Barth M. ECG Triggering in Ultra-High Field Cardiovascular MRI. ACTA ACUST UNITED AC 2016; 2:167-174. [PMID: 30042961 PMCID: PMC6024401 DOI: 10.18383/j.tom.2016.00193] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Cardiac magnetic resonance imaging at ultra-high field (B0 ≥ 7 T) potentially provides improved resolution and new opportunities for tissue characterization. Although an accurate synchronization of the acquisition to the cardiac cycle is essential, electrocardiogram (ECG) triggering at ultra-high field can be significantly impacted by the magnetohydrodynamic (MHD) effect. Blood flow within a static magnetic field induces a voltage, which superimposes the ECG and often affects the recognition of the R-wave. The MHD effect scales with B0 and is particularly pronounced at ultra-high field creating triggering-related image artifacts. Here, we investigated the performance of a conventional 3-lead ECG trigger device and a state-of-the-art trigger algorithm for cardiac ECG synchronization at 7 T. We show that by appropriate subject preparation and by including a learning phase for the R-wave detection outside of the magnetic field, reliable ECG triggering is feasible in healthy subjects at 7 T without additional equipment. Ultra-high field cardiac imaging was performed with the ECG signal and the trigger events recorded in 8 healthy subjects. Despite severe ECG signal distortions, synchronized imaging was successfully performed. Recorded ECG signals, vectorcardiograms, and large consistency in trigger event spacing indicate high accuracy for R-wave detection.
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Affiliation(s)
- Daniel Stäb
- The Centre for Advanced Imaging, The University of Queensland, Brisbane, Queensland, Australia.,Department of Diagnostic and Interventional Radiology, University of Würzburg, Würzburg, Germany
| | | | | | - Christian Hamilton-Craig
- Richard Slaughter Centre of Excellence in CVMRI, The Prince Charles Hospital, Brisbane, Queensland, Australia
| | - Markus Barth
- The Centre for Advanced Imaging, The University of Queensland, Brisbane, Queensland, Australia
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Han F, Zhou Z, Han E, Gao Y, Nguyen KL, Finn JP, Hu P. Self-gated 4D multiphase, steady-state imaging with contrast enhancement (MUSIC) using rotating cartesian K-space (ROCK): Validation in children with congenital heart disease. Magn Reson Med 2016; 78:472-483. [PMID: 27529745 DOI: 10.1002/mrm.26376] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Revised: 06/27/2016] [Accepted: 07/19/2016] [Indexed: 12/27/2022]
Abstract
PURPOSE To develop and validate a cardiac-respiratory self-gating strategy for the recently proposed multiphase steady-state imaging with contrast enhancement (MUSIC) technique. METHODS The proposed SG strategy uses the ROtating Cartesian K-space (ROCK) sampling, which allows for retrospective k-space binning based on motion surrogates derived from k-space center line. The k-space bins are reconstructed using a compressed sensing algorithm. Ten pediatric patients underwent cardiac MRI for clinical reasons. The original MUSIC and 2D-CINE images were acquired as a part of the clinical protocol, followed by the ROCK-MUSIC acquisition, all under steady-state intravascular distribution of ferumoxytol. Subjective scores and image sharpness were used to compare the images of ROCK-MUSIC and original MUSIC. RESULTS All scans were completed successfully without complications. The ROCK-MUSIC acquisition took 5 ± 1 min, compared to 8 ± 2 min for the original MUSIC. Image scores of ROCK-MUSIC were significantly better than original MUSIC at the ventricular outflow tracts (3.9 ± 0.3 vs. 3.3 ± 0.6, P < 0.05). There was a strong trend toward superior image scores for ROCK-MUSIC in the other anatomic locations. CONCLUSION ROCK-MUSIC provided images of equal or superior image quality compared to original MUSIC, and this was achievable with 40% savings in scan time and without the need for physiologic signal. Magn Reson Med 78:472-483, 2017. © 2016 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Fei Han
- Department of Radiological Sciences, David Geffen School of Medicine, University of California, Los Angeles, California, USA.,Department of Bioengineering, University of California, Los Angeles, California, USA
| | - Ziwu Zhou
- Department of Radiological Sciences, David Geffen School of Medicine, University of California, Los Angeles, California, USA.,Department of Bioengineering, University of California, Los Angeles, California, USA
| | - Eric Han
- Harvard Westlake School, Los Angeles, California, USA
| | - Yu Gao
- Department of Radiological Sciences, David Geffen School of Medicine, University of California, Los Angeles, California, USA.,Biomedical Physics Inter-Departmental Graduate Program, University of California, Los Angeles, California, USA
| | - Kim-Lien Nguyen
- Department of Radiological Sciences, David Geffen School of Medicine, University of California, Los Angeles, California, USA.,Division of Cardiology, VA Greater Los Angeles Healthcare System, Los Angeles, California, USA
| | - J Paul Finn
- Department of Radiological Sciences, David Geffen School of Medicine, University of California, Los Angeles, California, USA
| | - Peng Hu
- Department of Radiological Sciences, David Geffen School of Medicine, University of California, Los Angeles, California, USA.,Biomedical Physics Inter-Departmental Graduate Program, University of California, Los Angeles, California, USA
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Deserno TM, Marx N. Computational Electrocardiography: Revisiting Holter ECG Monitoring. Methods Inf Med 2016; 55:305-11. [PMID: 27406338 DOI: 10.3414/me15-05-0009] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Accepted: 10/07/2015] [Indexed: 11/09/2022]
Abstract
BACKGROUND Since 1942, when Goldberger introduced the 12-lead electrocardiography (ECG), this diagnostic method has not been changed. OBJECTIVES After 70 years of technologic developments, we revisit Holter ECG from recording to understanding. METHODS A fundamental change is fore-seen towards "computational ECG" (CECG), where continuous monitoring is producing big data volumes that are impossible to be inspected conventionally but require efficient computational methods. We draw parallels between CECG and computational biology, in particular with respect to computed tomography, computed radiology, and computed photography. From that, we identify technology and methodology needed for CECG. RESULTS Real-time transfer of raw data into meaningful parameters that are tracked over time will allow prediction of serious events, such as sudden cardiac death. Evolved from Holter's technology, portable smartphones with Bluetooth-connected textile-embedded sensors will capture noisy raw data (recording), process meaningful parameters over time (analysis), and transfer them to cloud services for sharing (handling), predicting serious events, and alarming (understanding). To make this happen, the following fields need more research: i) signal processing, ii) cycle decomposition; iii) cycle normalization, iv) cycle modeling, v) clinical parameter computation, vi) physiological modeling, and vii) event prediction. CONCLUSIONS We shall start immediately developing methodology for CECG analysis and understanding.
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Affiliation(s)
- Thomas M Deserno
- Prof. Dr. Thomas Martin Deserno, Aachen University of Technology (RWTH), Department of Medical Informatics, Pauwelsstraße 30, 52074 Aachen, Germany, E-mail:
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Wittlinger T, Martinovic I, Moritz A, Romanzetti S. Evaluation of the Spatial Resolution with 1.5–4 Tesla in a Stenosis Model. Asian Cardiovasc Thorac Ann 2016; 14:387-93. [PMID: 17005885 DOI: 10.1177/021849230601400508] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Since it was first described in the early 1990s, magnetic resonance coronary angiography has evolved into a promising noninvasive modality for imaging the coronary arteries. The aim of this study was to evaluate the detection accuracy and spatial resolution of vascular stenosis in contrast-enhanced 3-dimensional magnetic resonance angiography on a flow phantom. The examinations were performed with 1.5, 3, and 4 T whole-body imaging systems. For imaging at 4 T, we used a gradient-echo-multi-slice sequence. The system was flushed with gadopentetate dimeglumine contrast medium at flow rates of 40 and 60 mL·min−1. The accurate detection of in vitro stenoses was possible in segments of 0.4 mm in diameter at 4 T. The best results were obtained at a flow velocity of 40 mL·min−1 and a contrast medium concentration of 0.2 mmol·L−1. Contrast-enhanced high-field 3-dimensional magnetic resonance imaging provided a highly accurate evaluation of the degree of stenosis in this model. Exact evaluation of vessel diameters < 0.4 mm was not possible, even with 4 T. In vivo studies are necessary to overcome the current limitations in the visualization of small distal vessel segments.
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Affiliation(s)
- Thomas Wittlinger
- , Department of Thoracic and Cardiovascular Surgery, University Hospital, Theodor-Stern-Kai 7, Frankfurt 60590, Germany.
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Gregory TS, Cheng R, Tang G, Mao L, Tse ZTH. The Magnetohydrodynamic Effect and its Associated Material Designs for Biomedical Applications: A State-of-the-Art Review. ADVANCED FUNCTIONAL MATERIALS 2016; 26:3942-3952. [PMID: 29527149 PMCID: PMC5844576 DOI: 10.1002/adfm.201504198] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The presented article discusses recent advances in biomedical applications of classical Magnetohydrodynamics (MHD), with a focus on operating principles and associated material considerations. These applications address novel approaches to common biomedical problems from micro-particle sorting for lab-on-a-chip devices to advanced physiological monitoring techniques. 100 papers in the field of MHDs were reviewed with a focus on studies with direct biomedical applications. The body of literature was categorized into three primary areas of research including Material Considerations for MHD Applications, MHD Actuation Devices, and MHD Sensing Techniques. The state of the art in the field was examined and research topics were connected to provide a wide view of the field of biomedical MHDs. As this field develops, the need for advanced simulation and material design will continue to increase in importance in order to further expand its reach to maturity. As the field of biomedical MHDs continues to grow, advances towards micro-scale transitions will continue to be made, maintaining its clinically driven nature and moving towards real-world applications.
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Affiliation(s)
- T Stan Gregory
- College of Engineering, The University of Georgia, 597 D.W. Brooks Drive, Athens, GA 30602, USA
| | - Rui Cheng
- College of Engineering, The University of Georgia, 597 D.W. Brooks Drive, Athens, GA 30602, USA
| | - Guoyi Tang
- Advanced Materials Institute, Graduate School at Shenzhen, Tsinghua University 518055, China
| | - Leidong Mao
- College of Engineering, The University of Georgia, 597 D.W. Brooks Drive, Athens, GA 30602, USA
| | - Zion Tsz Ho Tse
- College of Engineering, The University of Georgia, 597 D.W. Brooks Drive, Athens, GA 30602, USA
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Abstract
Subject motion is unavoidable in clinical and research imaging studies. Breathing is the most important source of motion in whole-body PET and MRI studies, affecting not only thoracic organs but also those in the upper and even lower abdomen. The motion related to the pumping action of the heart is obviously relevant in high-resolution cardiac studies. These two sources of motion are periodic and predictable, at least to a first approximation, which means certain techniques can be used to control the motion (eg, by acquiring the data when the organ of interest is relatively at rest). Additionally, nonperiodic and unpredictable motion can also occur during the scan. One obvious limitation of methods relying on external devices (eg, respiratory bellows or the electrocardiogram signal to monitor the respiratory or cardiac cycle, respectively) to trigger or gate the data acquisition is that the complex motion of internal organs cannot be fully characterized. However, detailed information can be obtained using either the PET or MRI data (or both) allowing the more complete characterization of the motion field so that a motion model can be built. Such a model and the information derived from simple external devices can be used to minimize the effects of motion on the collected data. In the ideal case, all the events recorded during the PET scan would be used to generate a motion-free or corrected PET image. The detailed motion field can be used for this purpose by applying it to the PET data before, during, or after the image reconstruction. Integrating all these methods for motion control, characterization, and correction into a workflow that can be used for routine clinical studies is challenging but could potentially be extremely valuable given the improvement in image quality and reduction of motion-related image artifacts.
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Affiliation(s)
- Ciprian Catana
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA.
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Yerly J, Ginami G, Nordio G, Coristine AJ, Coppo S, Monney P, Stuber M. Coronary endothelial function assessment using self-gated cardiac cine MRI andk-tsparse SENSE. Magn Reson Med 2015; 76:1443-1454. [DOI: 10.1002/mrm.26050] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Revised: 09/30/2015] [Accepted: 10/23/2015] [Indexed: 11/11/2022]
Affiliation(s)
- Jérôme Yerly
- Department of Radiology; University Hospital and University of Lausanne; Lausanne Switzerland
- Center for Biomedical Imaging; Lausanne Switzerland
| | - Giulia Ginami
- Department of Radiology; University Hospital and University of Lausanne; Lausanne Switzerland
- Center for Biomedical Imaging; Lausanne Switzerland
| | - Giovanna Nordio
- Department of Radiology; University Hospital and University of Lausanne; Lausanne Switzerland
- Center for Biomedical Imaging; Lausanne Switzerland
| | - Andrew J. Coristine
- Department of Radiology; University Hospital and University of Lausanne; Lausanne Switzerland
- Center for Biomedical Imaging; Lausanne Switzerland
| | - Simone Coppo
- Department of Radiology; University Hospital and University of Lausanne; Lausanne Switzerland
- Center for Biomedical Imaging; Lausanne Switzerland
| | - Pierre Monney
- Cardiac MR Center, Service of Cardiology; University Hospital of Lausanne; Lausanne Switzerland
| | - Matthias Stuber
- Department of Radiology; University Hospital and University of Lausanne; Lausanne Switzerland
- Center for Biomedical Imaging; Lausanne Switzerland
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Tse ZTH, Dumoulin CL, Clifford GD, Schweitzer J, Qin L, Oster J, Jerosch-Herold M, Kwong RY, Michaud G, Stevenson WG, Schmidt EJ. A 1.5T MRI-conditional 12-lead electrocardiogram for MRI and intra-MR intervention. Magn Reson Med 2015; 71:1336-47. [PMID: 23580148 DOI: 10.1002/mrm.24744] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
PURPOSE High-fidelity 12-lead electrocardiogram (ECG) is important for physiological monitoring of patients during MR-guided intervention and cardiac MRI. Issues in obtaining noncorrupted ECGs inside MRI include a superimposed magneto-hydro-dynamic voltage, gradient switching-induced voltages, and radiofrequency heating. These problems increase with magnetic field. The aim of this study is to develop and clinically validate a 1.5T MRI-conditional 12-lead ECG system. METHODS The system was constructed with transmission lines to reduce radiofrequency induction and switching circuits to remove induced voltages. Adaptive filters, trained by 12-lead measurements outside MRI and in two orientations inside MRI, were used to remove the magneto-hydro-dynamic voltage. The system was tested on 10 (one exercising) volunteers and four arrhythmia patients. RESULTS Switching circuits removed most imaging-induced voltages (residual noise <3% of the R-wave). Magneto-hydro-dynamic voltage removal provided intra-MRI ECGs that varied by <3.8% from those outside the MRI, preserving the true S-wave to T-wave segment. In premature ventricular contraction (PVC) patients, clean ECGs separated premature ventricular contraction and sinus rhythm beats. Measured heating was <1.5°C. The system reliably acquired multiphase (steady-state free precession) wall-motion-cine and phase-contrast-cine scans, including subjects in whom 4-lead gating failed. The system required a minimum repetition time of 4 ms to allow robust ECG processing. CONCLUSION High-fidelity intra-MRI 12-lead ECG is possible.
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Affiliation(s)
- Zion Tsz Ho Tse
- The University of Georgia, College of Engineering, Driftmier Engineering Center, 597 D. W. Brook Drive, Athens, GA 30602, USA
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Ohyama Y, Ambale-Venkatesh B, Chamera E, Shehata ML, Corona-Villalobos CP, Zimmerman SL, Hassoun PM, Bluemke DA, Lima JA. Comparison of strain measurement from multimodality tissue tracking with strain-encoding MRI and harmonic phase MRI in pulmonary hypertension. Int J Cardiol 2015; 182:342-348. [DOI: 10.1016/j.ijcard.2015.01.016] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Revised: 12/02/2014] [Accepted: 01/04/2015] [Indexed: 10/24/2022]
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Likhite D, Adluru G, Hu N, McGann C, DiBella E. Quantification of myocardial perfusion with self-gated cardiovascular magnetic resonance. J Cardiovasc Magn Reson 2015; 17:14. [PMID: 25827080 PMCID: PMC4325943 DOI: 10.1186/s12968-015-0109-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Accepted: 12/31/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Current myocardial perfusion measurements make use of an ECG-gated pulse sequence to track the uptake and washout of a gadolinium-based contrast agent. The use of a gated acquisition is a problem in situations with a poor ECG signal. Recently, an ungated perfusion acquisition was proposed but it is not known how accurately quantitative perfusion estimates can be made from such datasets that are acquired without any triggering signal. METHODS An undersampled saturation recovery radial turboFLASH pulse sequence was used in 7 subjects to acquire dynamic contrast-enhanced images during free-breathing. A single saturation pulse was followed by acquisition of 4-5 slices after a delay of ~40 msec. This was repeated without pause and without any type of gating. The same pulse sequence, with ECG-gating, was used to acquire gated data as a ground truth. An iterative spatio-temporal constrained reconstruction was used to reconstruct the undersampled images. After reconstruction, the ungated images were retrospectively binned ("self-gated") into two cardiac phases using a region of interest based technique and deformably registered into near-systole and near-diastole. The gated and the self-gated datasets were then quantified with standard methods. RESULTS Regional myocardial blood flow estimates (MBFs) obtained using self-gated systole (0.64 ± 0.26 ml/min/g), self-gated diastole (0.64 ± 0.26 ml/min/g), and ECG-gated scans (0.65 ± 0.28 ml/min/g) were similar. Based on the criteria for interchangeable methods listed in the statistical analysis section, the MBF values estimated from self-gated and gated methods were not significantly different. CONCLUSION The self-gated technique for quantification of regional myocardial perfusion matched ECG-gated perfusion measurements well in normal subjects at rest. Self-gated systolic perfusion values matched ECG-gated perfusion values better than did diastolic values.
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Affiliation(s)
- Devavrat Likhite
- />Department of Radiology, Utah Center for Advanced Imaging Research, University of Utah, Salt Lake City, UT USA
| | - Ganesh Adluru
- />Department of Radiology, Utah Center for Advanced Imaging Research, University of Utah, Salt Lake City, UT USA
| | - Nan Hu
- />Department of Internal Medicine, University of Utah, Salt Lake City, UT USA
| | - Chris McGann
- />Division of Cardiology, University of Utah, Salt Lake City, UT USA
| | - Edward DiBella
- />Department of Radiology, Utah Center for Advanced Imaging Research, University of Utah, Salt Lake City, UT USA
- />Department of Bioengineering, University of Utah, Salt Lake City, UT USA
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Optimization of free-breathing whole-heart 3-dimensional cardiac magnetic resonance imaging at 3 tesla to identify coronary vein anatomy and to compare with multidetector computed tomography. J Comput Assist Tomogr 2015; 38:941-8. [PMID: 24983436 DOI: 10.1097/rct.0000000000000131] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
OBJECTIVE This study optimizes use of 3-T magnetic resonance imaging (MRI) to delineate coronary venous anatomy and compares 3-T MRI with multidetector computed tomography (MDCT) measurements. METHODS The study population included 37 consecutive subjects (22 men, 19-71 years old). Whole-heart contrast-enhanced MRI images at 3 T were acquired using segmented k-space gradient echo with inversion recovery prepared technique. The MDCT images were obtained using nonionic iodinated contrast. RESULTS The coronary sinus and great cardiac, posterior interventricular, and anterior interventricular veins were visualized in 100% of cases by both MRI and MDCT. Detection of the posterior vein of the left ventricle and the left marginal vein by MRI was 97% and 81%, respectively. Bland-Altman plots showed agreement in ostial diameter measured by both modalities with correlation coefficients ranging from 0.5 to 0.76. Vein length and distances also agreed closely. CONCLUSIONS Free-breathing whole-heart 3-dimensional MRI at 3 T provides high-spatial-resolution images and could offer an alternative imaging technique instead of MDCT scans.
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Gregory TS, Schmidt EJ, Zhang SH, Kwong RY, Stevenson WG, Murrow JR, Ho Tse ZT. Left-ventricular mechanical activation and aortic-arch orientation recovered from magneto-hydrodynamic voltages observed in 12-lead ECGs obtained inside MRIs: a feasibility study. Ann Biomed Eng 2014; 42:2480-9. [PMID: 25224074 PMCID: PMC4241154 DOI: 10.1007/s10439-014-1109-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Accepted: 09/04/2014] [Indexed: 10/24/2022]
Abstract
To explore use of the Magnetohydrodynamic Voltage (VMHD), observed in intra-MRI 12-lead electrocardiograms (ECG), to indicate the timing of the onset of left-ventricular mechanical activation (LVMA) and the orientation of the aortic-arch (AAO). Blood flow through the aortic arch during systole, in the presence of the MRI magnetic field (B 0), generates VMHD. Since the magnitude and direction of VMHD are determined by the timing and directionality of blood flow relative to B 0, we hypothesized that clinically useful measures, LVMA and AAO, could be extracted from temporal and vectorial VMHD characteristics. VMHD signals were extracted from 12-lead ECG traces by comparing traces obtained inside and outside the MRI scanner. VMHD was converted into the Vectorcardiogram frame of reference. LVMA was quantified in 1 subject at 1.5T and 3 subjects at 3T, and the result compared to CINE MRI. AAO was inferred for 4 subjects at 3T and compared to anatomical imaging of the aortic arch orientation in the transverse plane. A < 10% error was observed in LVMA measurements, while a < 3° error was observed in aortic arch orientation measurements. The temporal and vectorial nature of VMHD is useful in estimating these clinically relevant parameters.
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Affiliation(s)
- T. Stan Gregory
- College of Engineering, The University of Georgia, Athens, GA, USA
| | - Ehud J. Schmidt
- Cardiology and Radiology, Brigham and Women’s Hospital, Boston, MA, USA
| | | | - Raymond Y. Kwong
- Cardiology and Radiology, Brigham and Women’s Hospital, Boston, MA, USA
| | | | | | - Zion Tsz Ho Tse
- College of Engineering, The University of Georgia, Athens, GA, USA
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