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Chen C, Liu Y, Simonetti OP, Tong M, Jin N, Bacher M, Speier P, Ahmad R. Cardiac and respiratory motion extraction for MRI using pilot tone-a patient study. THE INTERNATIONAL JOURNAL OF CARDIOVASCULAR IMAGING 2024; 40:93-105. [PMID: 37874445 PMCID: PMC10842141 DOI: 10.1007/s10554-023-02966-z] [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: 07/14/2023] [Accepted: 09/21/2023] [Indexed: 10/25/2023]
Abstract
This study aims to evaluate the accuracy and reliability of the cardiac and respiratory signals extracted from Pilot Tone (PT) in patients clinically referred for cardiovascular MRI. Twenty-three patients were scanned under free-breathing conditions using a balanced steady-state free-precession real-time (RT) cine sequence on a 1.5T scanner. The PT signal was generated by a built-in PT transmitter integrated within the body array coil, and retrospectively processed to extract respiratory and cardiac signals. For comparison, ECG and BioMatrix (BM) respiratory sensor signals were also synchronously recorded. To assess the performances of PT, ECG, and BM, cardiac and respiratory signals extracted from the RT cine images were used as the ground truth. The respiratory motion extracted from PT correlated positively with the image-derived respiratory signal in all cases and showed a stronger correlation (absolute coefficient: 0.95 ± 0.09) than BM (0.72 ± 0.24). For the cardiac signal, PT trigger jitter (standard deviation of PT trigger locations relative to ECG triggers) ranged from 6.6 to 83.3 ms, with a median of 21.8 ms. The mean absolute difference between the PT and corresponding ECG cardiac cycle duration was less than 5% of the average ECG RR interval for 21 out of 23 patients. We did not observe a significant linear dependence (p > 0.28) of PT delay and PT jitter on the patients' BMI or cardiac cycle duration. This study demonstrates the potential of PT to monitor both respiratory and cardiac motion in patients clinically referred for cardiovascular MRI.
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Affiliation(s)
- Chong Chen
- Department of Biomedical Engineering, The Ohio State University, Columbus, US.
| | - Yingmin Liu
- Davis Heart & Lung Research Institute, The Ohio State University, Columbus, US
| | - Orlando P Simonetti
- Davis Heart & Lung Research Institute, The Ohio State University, Columbus, US
| | - Matthew Tong
- Davis Heart & Lung Research Institute, The Ohio State University, Columbus, US
| | - Ning Jin
- Siemens Medical Solutions USA, Inc, Columbus, US
| | | | | | - Rizwan Ahmad
- Department of Biomedical Engineering, The Ohio State University, Columbus, US
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2
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von Kleist H, Buehrer M, Kozerke S, Saengsin K, Harrington JK, Powell AJ, Moghari MH. Cardiac self-gating using blind source separation for 2D cine cardiovascular magnetic resonance imaging. Magn Reson Imaging 2021; 81:42-52. [PMID: 33905835 DOI: 10.1016/j.mri.2021.04.008] [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: 01/10/2021] [Revised: 04/11/2021] [Accepted: 04/21/2021] [Indexed: 10/21/2022]
Abstract
PURPOSE To develop and validate a new cardiac self-gating algorithm using blind source separation for 2D cine steady-state free precession (SSFP) imaging. METHODS A standard cine SSFP sequence was modified so that the center point of k-space was sampled with each excitation. The center points of k-space were processed by 4 blind source separation methods, and used to detect heartbeats and assign k-space data to appropriate time points in the cardiac cycle. The proposed self-gating technique was prospectively validated in 8 patients against the standard electrocardiogram (ECG)-gating method by comparing the cardiac cycle lengths, image quality metrics, and ventricular volume measurements. RESULTS There was close agreement between the cardiac cycle length using the ECG- and self-gating methods (bias 0.0 bpm, 95% limits of agreement ±2.1 bpm). The image quality metrics were not significantly different between the ECG- and self-gated images. The ventricular volumes, stroke volumes, and mass measured from self-gated images were all comparable with those from ECG-gated images (all biases <5%). CONCLUSION The self-gating method yielded comparable cardiac cycle length, image quality, and ventricular measurements compared with standard ECG-gated cine imaging. It may simplify patient preparation, be more robust when there is arrhythmia, and allow cardiac gating at higher field strengths.
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Affiliation(s)
- Henrik von Kleist
- Department of Cardiology, Boston Children's Hospital, and Department of Pediatrics, Harvard Medical School, Boston, MA, USA; Department of Informatics, Technical University of Munich, Garching, Germany.
| | - Martin Buehrer
- Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland
| | - Sebastian Kozerke
- Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland
| | - Kwannapas Saengsin
- Department of Cardiology, Boston Children's Hospital, and Department of Pediatrics, Harvard Medical School, Boston, MA, USA
| | - Jamie K Harrington
- Department of Cardiology, Boston Children's Hospital, and Department of Pediatrics, Harvard Medical School, Boston, MA, USA
| | - Andrew J Powell
- Department of Cardiology, Boston Children's Hospital, and Department of Pediatrics, Harvard Medical School, Boston, MA, USA
| | - Mehdi H Moghari
- Department of Cardiology, Boston Children's Hospital, and Department of Pediatrics, Harvard Medical School, Boston, MA, USA
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3
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Zhou R, Yang Y, Mathew RC, Mugler JP, Weller DS, Kramer CM, Ahmed AH, Jacob M, Salerno M. Free-breathing cine imaging with motion-corrected reconstruction at 3T using SPiral Acquisition with Respiratory correction and Cardiac Self-gating (SPARCS). Magn Reson Med 2019; 82:706-720. [PMID: 31006916 DOI: 10.1002/mrm.27763] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Revised: 03/12/2019] [Accepted: 03/15/2019] [Indexed: 12/28/2022]
Abstract
PURPOSE To develop a continuous-acquisition cardiac self-gated spiral pulse sequence and a respiratory motion-compensated reconstruction strategy for free-breathing cine imaging. METHODS Cine data were acquired continuously on a 3T scanner for 8 seconds per slice without ECG gating or breath-holding, using a golden-angle gradient echo spiral pulse sequence. Cardiac motion information was extracted by applying principal component analysis on the gridded 8 × 8 k-space center data. Respiratory motion was corrected by rigid registration on each heartbeat. Images were reconstructed using a low-rank and sparse (L+S) technique. This strategy was evaluated in 37 healthy subjects and 8 subjects undergoing clinical cardiac MR studies. Image quality was scored (1-5 scale) in a blinded fashion by 2 experienced cardiologists. In 13 subjects with whole-heart coverage, left ventricular ejection fraction (LVEF) from SPiral Acquisition with Respiratory correction and Cardiac Self-gating (SPARCS) was compared to that from a standard ECG-gated breath-hold balanced steady-state free precession (bSSFP) cine sequence. RESULTS The self-gated signal was successfully extracted in all cases and demonstrated close agreement with the acquired ECG signal (mean bias, -0.22 ms). The mean image score across all subjects was 4.0 for reconstruction using the L+S model. There was good agreement between the LVEF derived from SPARCS and the gold-standard bSSFP technique. CONCLUSION SPARCS successfully images cardiac function without the need for ECG gating or breath-holding. With an 8-second data acquisition per slice, whole-heart cine images with clinically acceptable spatial and temporal resolution and image quality can be acquired in <90 seconds of free-breathing acquisition.
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Affiliation(s)
- Ruixi Zhou
- Department of Biomedical Engineering, University of Virginia Health System, Charlottesville, Virginia
| | - Yang Yang
- Department of Medicine, Cardiovascular Division, University of Virginia Health System, Charlottesville, Virginia.,Translational and Molecular Imaging Institute and Department of Radiology, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Roshin C Mathew
- Department of Medicine, Cardiovascular Division, University of Virginia Health System, Charlottesville, Virginia.,Radiology and Medical Imaging, University of Virginia Health System, Charlottesville, Virginia
| | - John P Mugler
- Department of Biomedical Engineering, University of Virginia Health System, Charlottesville, Virginia.,Department of Medicine, Cardiovascular Division, University of Virginia Health System, Charlottesville, Virginia.,Radiology and Medical Imaging, University of Virginia Health System, Charlottesville, Virginia
| | - Daniel S Weller
- Department of Electrical and Computer Engineering, University of Virginia, Charlottesville, Virginia
| | - Christopher M Kramer
- Department of Medicine, Cardiovascular Division, University of Virginia Health System, Charlottesville, Virginia.,Radiology and Medical Imaging, University of Virginia Health System, Charlottesville, Virginia
| | - Abdul Haseeb Ahmed
- Department of Electrical and Computer Engineering, University of Iowa, Iowa City, Iowa
| | - Mathews Jacob
- Department of Electrical and Computer Engineering, University of Iowa, Iowa City, Iowa
| | - Michael Salerno
- Department of Biomedical Engineering, University of Virginia Health System, Charlottesville, Virginia.,Department of Medicine, Cardiovascular Division, University of Virginia Health System, Charlottesville, Virginia.,Radiology and Medical Imaging, University of Virginia Health System, Charlottesville, Virginia
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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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5
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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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6
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Bonanno G, Hays AG, Weiss RG, Schär M. Self-gated golden angle spiral cine MRI for coronary endothelial function assessment. Magn Reson Med 2018; 80:560-570. [PMID: 29282752 PMCID: PMC5910207 DOI: 10.1002/mrm.27060] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Revised: 12/01/2017] [Accepted: 12/05/2017] [Indexed: 01/28/2023]
Abstract
PURPOSE Depressed coronary endothelial function (CEF) is a marker for atherosclerotic disease, an independent predictor of cardiovascular events, and can be quantified non-invasively with ECG-triggered spiral cine MRI combined with isometric handgrip exercise (IHE). However, MRI-CEF measures can be hindered by faulty ECG-triggering, leading to prolonged breath-holds and degraded image quality. Here, a self-gated golden angle spiral method (SG-GA) is proposed to eliminate the need for ECG during cine MRI. METHODS SG-GA was tested against retrospectively ECG-gated golden angle spiral MRI (ECG-GA) and gold-standard ECG-triggered spiral cine MRI (ECG-STD) in 10 healthy volunteers. CEF data were obtained from cross-sectional images of the proximal right and left coronary arteries in a 3T scanner. Self-gating heart rates were compared to those from simultaneous ECG-gating. Coronary vessel sharpness and cross-sectional area (CSA) change with IHE were compared among the 3 methods. RESULTS Self-gating precision, accuracy, and correlation-coefficient were 7.7 ± 0.5 ms, 9.1 ± 0.7 ms, and 0.93 ± 0.01, respectively (mean ± standard error). Vessel sharpness by SG-GA was equal or higher than ECG-STD (rest: 63.0 ± 1.7% vs. 61.3 ± 1.3%; exercise: 62.6 ± 1.3% vs. 56.7 ± 1.6%, P < 0.05). CSA changes were in agreement among the 3 methods (ECG-STD = 8.7 ± 4.0%, ECG-GA = 9.6 ± 3.1%, SG-GA = 9.1 ± 3.5%, P = not significant). CONCLUSION CEF measures can be obtained with the proposed self-gated high-quality cine MRI method even when ECG is faulty or not available. Magn Reson Med 80:560-570, 2018. © 2017 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Gabriele Bonanno
- Division of Cardiology, Department of Medicine, Johns Hopkins University, Baltimore, MD
- Division of MR Research, Russel H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University, Baltimore, MD
| | - Allison G. Hays
- Division of Cardiology, Department of Medicine, Johns Hopkins University, Baltimore, MD
| | - Robert G. Weiss
- Division of Cardiology, Department of Medicine, Johns Hopkins University, Baltimore, MD
- Division of MR Research, Russel H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University, Baltimore, MD
| | - Michael Schär
- Division of MR Research, Russel H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University, Baltimore, MD
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7
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Oster J, Clifford GD. Acquisition of electrocardiogram signals during magnetic resonance imaging. Physiol Meas 2017; 38:R119-R142. [PMID: 28430109 DOI: 10.1088/1361-6579/aa6e8c] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The recording of the electrocardiogram (ECG) during magnetic resonance imaging (MRI) acquisition is of great interest and importance. Firstly, MRI acquisition is a relatively slow process, which therefore complicates the imaging of moving organs. Cardiac MRI requires the development of strategies for acquiring high quality images, which is mainly achieved by synchronising the image acquisition with a specific time during the cardiac cycle. The ECG is used to monitor the heart's activity, and the detection of the largest and steepest peak in the cardiac cycle (the QRS complex) triggers the acquisition of slices of the k-space. Secondly, patients undergoing an MRI examination need to be monitored for safety during the procedure, and therefore ECG signals are used to track their cardiovascular state in real time. However, there are significant barriers to the accurate observation and processing of the ECG during MRI acquisition. In particular, the flow of charged blood particles through the large applied magnetic field leads to an extra current source, known as the magnetohdrodymanic (MHD) effect. This review article discusses these barriers and state-of-the-art solutions. An overview of the relevant technology including hardware and applications are described. The development of new software tools for the processing of the ECG signals acquired during MRI is also detailed. These developments include the design of specific QRS detection algorithms, which are able to distinguish QRS complexes from the MHD effect but also the gradient artefacts. Different techniques for the suppression of the gradient artefacts are also presented as well as the most challenging problem to-date-the problem of separating the MHD effect from the ECG. The article concludes by summarising the advantages of using ECG signals during MRI, but also presents the current limitations of modern analysis techniques in this domain. The most promising avenues of research are also discussed and suggestions for new methodological analyses for the development of this field are given.
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Affiliation(s)
- Julien Oster
- IADI, U947, INSERM, Université de Lorraine, CHRU Nancy, Vandoeuvre-les-Nancy, France
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8
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Abstract
BACKGROUND To develop a prospective cardiac motion self-gating method that provides robust and accurate cardiac triggers in real time. METHODS The proposed self-gating method consists of an "imaging mode" that acquires the k-space segments and a "self-gating mode" that captures the cardiac motion by repeatedly sampling the k-space centerline. A training based principal component analysis algorithm is utilized to process the self-gating data where the projection onto the first principal component was used as the self-gating signal. Retrospective studies using a sequence with self-gating mode only was performed on 8 healthy subjects to validate the accuracy and reliability of the self-gating triggers. Prospective studies using both ECG-gated and self-gated cardiac CINE sequences were conducted on 6 healthy subjects to compare the image quality. RESULTS Using the ECG as the reference, the proposed method was able to detect self-gating triggers within ±10 ms accuracy on all 8 subjects in the retrospective study. The prospectively self-gated CINE sequence successfully detected 100% of the cardiac triggers and provided excellent CINE image quality without using ECG signals. CONCLUSIONS The proposed cardiac self-gating method is a robust and accurate alternative to conventional ECG-based gating method for a number of cardiac MRI applications.
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Affiliation(s)
- Fei Han
- Department of Radiological Sciences, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
| | - Stanislas Rapacchi
- Department of Radiological Sciences, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
| | - Peng Hu
- Department of Radiological Sciences, David Geffen School of Medicine, University of California, Los Angeles, CA, USA.,Biomedical Physics Inter-Departmental Graduate Program, University of California, Los Angeles, CA, USA
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9
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Zhu Y, Spincemaille P, Liu J, Li S, Nguyen TD, Prince MR, Xie Y, Wang Y. Nonlinear profile order for three-dimensional hybrid radial acquisition applied to self-gated free-breathing cardiac cine MRI. CHINESE PHYSICS B 2017; 26:018701. [DOI: 10.1088/1674-1056/26/1/018701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/29/2024]
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10
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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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11
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Bassett EC, Kholmovski EG, Wilson BD, DiBella EVR, Dosdall DJ, Ranjan R, McGann CJ, Kim D. Evaluation of highly accelerated real-time cardiac cine MRI in tachycardia. NMR IN BIOMEDICINE 2014; 27:175-182. [PMID: 24259281 DOI: 10.1002/nbm.3049] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Revised: 10/08/2013] [Accepted: 10/10/2013] [Indexed: 06/02/2023]
Abstract
Electrocardiogram (ECG)-gated breath-hold cine MRI is considered to be the gold standard test for the assessment of cardiac function. However, it may fail in patients with arrhythmia, impaired breath-hold capacity and poor ECG gating. Although ungated real-time cine MRI may mitigate these problems, commercially available real-time cine MRI pulse sequences using parallel imaging typically yield relatively poor spatiotemporal resolution because of their low image acquisition efficiency. As an extension of our previous work, the purpose of this study was to evaluate the diagnostic quality and accuracy of eight-fold-accelerated real-time cine MRI with compressed sensing (CS) for the quantification of cardiac function in tachycardia, where it is challenging for real-time cine MRI to provide sufficient spatiotemporal resolution. We evaluated the performances of eight-fold-accelerated cine MRI with CS, three-fold-accelerated real-time cine MRI with temporal generalized autocalibrating partially parallel acquisitions (TGRAPPA) and ECG-gated breath-hold cine MRI in 21 large animals with tachycardia (mean heart rate, 104 beats per minute) at 3T. For each cine MRI method, two expert readers evaluated the diagnostic quality in four categories (image quality, temporal fidelity of wall motion, artifacts and apparent noise) using a Likert scale (1-5, worst to best). One reader evaluated the left ventricular functional parameters. The diagnostic quality scores were significantly different between the three cine pulse sequences, except for the artifact level between CS and TGRAPPA real-time cine MRI. Both ECG-gated breath-hold cine MRI and eight-fold accelerated real-time cine MRI yielded all four scores of ≥ 3.0 (acceptable), whereas three-fold-accelerated real-time cine MRI yielded all scores below 3.0, except for artifact (3.0). The left ventricular ejection fraction (LVEF) measurements agreed better between ECG-gated cine MRI and eight-fold-accelerated real-time cine MRI (mean difference, -1.6%) than between ECG-gated cine MRI and three-fold-accelerated real-time cine MRI (mean difference, -5.7%). Eight-fold-accelerated real-time cine MRI with CS yields acceptable diagnostic quality and relatively accurate LVEF measurements in the challenging setting of tachycardia.
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Affiliation(s)
- Elwin C Bassett
- Department of Physics, University of Utah, Salt Lake City, UT, USA; UCAIR, Department of Radiology, University of Utah, Salt Lake City, UT, USA
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12
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Flow-gated radial phase-contrast imaging in the presence of weak flow. Int J Cardiovasc Imaging 2012; 29:131-40. [DOI: 10.1007/s10554-012-0056-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/22/2012] [Accepted: 04/17/2012] [Indexed: 11/26/2022]
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13
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Image-guided optimization of the ECG trace in cardiac MRI. Int J Cardiovasc Imaging 2011; 28:587-93. [DOI: 10.1007/s10554-011-9865-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/02/2010] [Accepted: 04/02/2011] [Indexed: 10/18/2022]
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14
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Manka R, Buehrer M, Boesiger P, Fleck E, Kozerke S. Performance of simultaneous cardiac-respiratory self-gated three-dimensional MR imaging of the heart: initial experience. Radiology 2010; 255:909-16. [PMID: 20501728 DOI: 10.1148/radiol.10091103] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
This study was approved by the local institutional ethics committee, and informed consent was obtained from all volunteers and patients. The objective of the present study was to assess the performance of high-spatial-resolution three-dimensional prospective cardiac-respiratory self-gated (CRSG) magnetic resonance (MR) imaging for determining left ventricular (LV) volumes and mass, as well as right ventricular (RV) volumes, in comparison with standard electrocardiography (ECG)-triggered, two-dimensional multisection, multiple-breath-hold cine imaging. The self-gated method derives cardiac triggering and respiratory gating information prospectively on the basis of additional MR imaging signals acquired in every repetition time and, thereby, eliminates the need for ECG triggering and multiple-breath-hold procedures. Data were acquired in 15 healthy volunteers (mean age, 27.2 years +/- 7.2 [standard deviation]) and 11 patients (mean age, 60.7 years +/- 11.3). The bias between the self-gating and the reference imaging techniques was minimal for all LV and RV parameters (mean values: LV end-diastolic volume, 2.0 mL; LV end-systolic volume, 0.6 mL; RV end-diastolic volume, 2.2 mL; and RV end-systolic volume, 0.8 mL). Prospective CRSG is a valuable alternative to ECG-triggered, multisection, multiple-breath-hold cine imaging of the heart and holds considerable promise for simplifying functional imaging of the heart, particularly in patients who are unable to hold their breath for a long period and patients who show ECG signal disturbances.
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Affiliation(s)
- Robert Manka
- Institute for Biomedical Engineering, University and ETH Zurich, Gloriastrasse 35, CH-8092 Zurich, Switzerland.
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15
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Park H, Park Y, Cho S, Jang B, Lee K. New cardiac MRI gating method using event-synchronous adaptive digital filter. Ann Biomed Eng 2009; 37:2170-87. [PMID: 19644754 DOI: 10.1007/s10439-009-9764-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2007] [Accepted: 07/21/2009] [Indexed: 11/29/2022]
Abstract
When imaging the heart using MRI, an artefact-free electrocardiograph (ECG) signal is not only important for monitoring the patient's heart activity but also essential for cardiac gating to reduce noise in MR images induced by moving organs. The fundamental problem in conventional ECG is the distortion induced by electromagnetic interference. Here, we propose an adaptive algorithm for the suppression of MR gradient artefacts (MRGAs) in ECG leads of a cardiac MRI gating system. We have modeled MRGAs by assuming a source of strong pulses used for dephasing the MR signal. The modeled MRGAs are rectangular pulse-like signals. We used an event-synchronous adaptive digital filter whose reference signal is synchronous to the gradient peaks of MRI. The event detection processor for the event-synchronous adaptive digital filter was implemented using the phase space method-a sort of topology mapping method-and least-squares acceleration filter. For evaluating the efficiency of the proposed method, the filter was tested using simulation and actual data. The proposed method requires a simple experimental setup that does not require extra hardware connections to obtain the reference signals of adaptive digital filter. The proposed algorithm was more effective than the multichannel approach.
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Affiliation(s)
- Hodong Park
- Department of Biomedical Engineering, College of Health Science, Yonsei University, 234 Maeji-Ri, Heungup-Myon, Wonju City, Kangwon Do, Korea.
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16
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Nijm GM, Sahakian AV, Swiryn S, Carr JC, Sheehan JJ, Larson AC. Comparison of self-gated cine MRI retrospective cardiac synchronization algorithms. J Magn Reson Imaging 2008; 28:767-72. [PMID: 18777546 DOI: 10.1002/jmri.21514] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
PURPOSE To determine whether improved self-gating (SG) algorithms can provide superior synchronization accuracy for retrospectively gated cine MRI. MATERIALS AND METHODS First difference, template matching, and polynomial fitting algorithms were implemented to improve the synchronization of MRI data using cardiac SG signals. Cine datasets were acquired during short-axis, two-, three-, and four-chamber cardiac MRI scans. The root-mean-square (RMS) error of SG synchronization positions compared to detected R-wave positions were calculated along with the mean square error (MSE) and peak signal-to-noise ratio (PSNR) comparing SG to electrocardiogram (ECG)-gated images. Overall image quality was also compared by two expert reviewers. RESULTS RMS errors were highest for the first difference method for all orientations. Improvements for both template matching and cubic polynomial fitting methods were significant for two-, three-, and four-chamber scans. MSE values were lower and PSNR were significantly higher for the cubic method compared to the first difference method for all orientations. Reviewers scored the images to be of comparable quality. CONCLUSION Template matching and polynomial fitting improved the accuracy of cardiac cycle synchronization for two-, three-, and four-chamber scans; improvements in SG synchronization accuracy were reflected in improvements in analytical image quality. Implementation of robust postprocessing algorithms may bring SG approaches closer to clinical utilization.
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Affiliation(s)
- Grace M Nijm
- Department of Electrical Engineering and Computer Science, Northwestern University, Evanston, Illinois 60208, USA
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17
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Buehrer M, Curcic J, Boesiger P, Kozerke S. Prospective self-gating for simultaneous compensation of cardiac and respiratory motion. Magn Reson Med 2008; 60:683-90. [DOI: 10.1002/mrm.21697] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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18
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Flow-compensated self-gating. MAGNETIC RESONANCE MATERIALS IN PHYSICS BIOLOGY AND MEDICINE 2008; 21:307-15. [PMID: 18668271 DOI: 10.1007/s10334-008-0131-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2008] [Revised: 07/15/2008] [Accepted: 07/16/2008] [Indexed: 10/21/2022]
Abstract
OBJECTIVE Self-gating (SG) is a method to record cardiac movement during MR imaging. It uses information from an additional short, non-spatially encoded data acquisition. This usually lengthens TE and increases the sensitivity to flow artifacts. A new flow compensation scheme optimized for self-gating sequences is introduced that has very little or no time penalty over self-gating sequences without flow compensation. MATERIALS AND METHODS Three variants of a self-gated 2D spoiled gradient echo or fast low angle shot (FLASH) sequence were implemented: without (noFC), with a conventional, serial (cFC), and with a new, time-efficient flow compensation (sFC). In experiments on volunteers and small animals, the sequence variants were compared with regard to the SG signal and the flow artifacts in the images. RESULTS Both cFC and sFC reduce flow artifacts in cardiac images. The SG signal of the sFC is more sensitive to physiological motion, so that a cardiac trigger can be extracted more precisely as in cFC. In a typical setting for small animal imaging, sFC technique reduces the echo/repetition time over cFC by about 23%/14%. CONCLUSION The time-efficient sFC technique provides flow-compensated images with cardiac triggering in both volunteers and small animals.
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Abi-Abdallah D, Robin V, Drochon A, Fokapu O. Alterations in human ECG due to the MagnetoHydroDynamic effect: a method for accurate R peak detection in the presence of high MHD artifacts. ACTA ACUST UNITED AC 2008; 2007:1842-5. [PMID: 18002339 DOI: 10.1109/iembs.2007.4352673] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Blood flow in high static magnetic fields induces elevated voltages that contaminate the ECG signal which is recorded simultaneously during MRI scans for synchronization purposes. This is known as the magnetohydrodynamic (MHD) effect, it increases the amplitude of the T wave, thus hindering correct R peak detection. In this paper, we inspect the MHD induced alterations of human ECG signals recorded in a 1.5 Tesla steady magnetic field and establish a primary characterization of the induced changes using time and frequency domain analysis. We also reexamine our previously developed real time algorithm for MRI cardiac gating and determine that, with a minor modification, this algorithm is capable of achieving perfect detection even in the presence of strong MHD artifacts.
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Affiliation(s)
- Dima Abi-Abdallah
- Laboratory of Biomechanics and Biomedical Engineering of the University of Technology of Compiègne, France.
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20
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Stehning C, Boernert P, Nehrke K. Advances in Coronary MRA from Vessel Wall to Whole Heart Imaging. Magn Reson Med Sci 2007; 6:157-70. [PMID: 18037796 DOI: 10.2463/mrms.6.157] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
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Abstract
The need for ECG gating presents many difficulties in cardiac magnetic resonance imaging (CMRI). Real-time imaging techniques eliminate the need for ECG gating in cine CMRI, but they cannot offer the spatial and temporal resolution provided by segmented acquisition techniques. Previous MR signal-based techniques have demonstrated an ability to provide cardiac gating information; however, these techniques result in decreased imaging efficiency. The purpose of this work was to develop a new "self-gated" (SG) acquisition technique that eliminates these efficiency deficits by extracting the motion synchronization signal directly from the same MR signals used for image reconstruction. Three separate strategies are proposed for deriving the SG signal from data acquired using radial k-space sampling: echo peak magnitude, kymogram, and 2D correlation. The SG techniques were performed on seven normal volunteers. A comparison of the results showed that they provided cine image series with no significant differences in image quality compared to that obtained with conventional ECG gating techniques. SG techniques represent an important practical advance in clinical MRI because they enable the acquisition of high temporal and spatial resolution cardiac cine images without the need for ECG gating and with no loss in imaging efficiency.
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Affiliation(s)
- Andrew C Larson
- Laboratory of Cardiac Energetics, NHLBI, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland 20892-1061, USA.
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22
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Crowe ME, Larson AC, Zhang Q, Carr J, White RD, Li D, Simonetti OP. Automated rectilinear self-gated cardiac cine imaging. Magn Reson Med 2004; 52:782-8. [PMID: 15389958 DOI: 10.1002/mrm.20212] [Citation(s) in RCA: 102] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
ECG-based gating in cardiac MR imaging requires additional patient preparation time, is susceptible to RF and magnetic interference, and is ineffective in a significant percentage of patients. "Wireless" or "self-gating" techniques have been described using either interleaved central k-space lines or projection reconstruction to obtain MR signals synchronous with the cardiac cycle. However, the interleaved, central line method results in a doubling of the acquisition time, while radial streak artifacts are encountered with the projection reconstruction method. In this work, a new self-gating technique is presented to overcome these limitations. A retrospectively gated TrueFISP cine sequence was modified to acquire a short second echo after the readout and phase gradients are rewound. The information obtained from this second echo was used to derive a gating signal. This technique was compared to ECG-based gating in 10 healthy volunteers and shown to have no significant difference in image quality. The results indicate that this method could serve as an alternative gating strategy without the need for external physiological signal detection.
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Affiliation(s)
- Mark E Crowe
- Department of Biomedical Engineering, Northwestern University, Chicago, Illinois 60611, USA
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Fischer SE, Wickline SA, Lorenz CH. Novel real-time R-wave detection algorithm based on the vectorcardiogram for accurate gated magnetic resonance acquisitions. Magn Reson Med 1999; 42:361-70. [PMID: 10440961 DOI: 10.1002/(sici)1522-2594(199908)42:2<361::aid-mrm18>3.0.co;2-9] [Citation(s) in RCA: 206] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Electrocardiograph (ECG) triggered or gated magnetic resonance methods are used in many imaging applications. Therefore, a reliable trigger signal derived from to the R-wave of the ECG is essential, especially in cardiac imaging. However, currently available methods often fail mainly due to the artifacts in the ECG generated by the MR scanner itself, such as the magnetohydrodynamic effect and gradient switching noise. The purpose this study was to characterize the accuracy of selected R-wave detection algorithms in an MR environment, and to develop novel approaches to eliminate imprecise triggering. Vectorcardiograms (VCG) in 12 healthy volunteers exposed to 1.5 T magnetic field were digitized and used as a reference data set including manually corrected onsets of R-waves. To define the magnetohydrodynamic effect, the VCGs were characterized in time, frequency, and spatial domains. The selected real-time R-wave detection algorithms, and a new "target-distance" VCG-based algorithm were applied either to standard surface leads calculated from the recorded VCG or to the VCG directly. The flow related artifact was higher in amplitude than the R-wave in 28% of the investigated VCGs which yielded up to 9-16%false positive detected QRS complexes for traditional algorithms. The "target-distance" R-wave detection algorithm yielded a score of 100% for detection with 0.2% false positives and was superior to all the other selected methods. Thus, the VCG of subjects exposed to a strong magnetic field can be use to separate the magnetohydrodynamic artifact and the actual R-wave, and markedly improves the trigger accuracy in gated magnetic resonance scans. Magn Reson Med 42:361-370, 1999.
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Affiliation(s)
- S E Fischer
- Cardiovascular Division, Center for Cardiovascular Magnetic Resonance, Barnes-Jewish Hospital at Washington University Medical Center, St. Louis, Missouri 63110, USA
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Felblinger J, Slotboom J, Kreis R, Jung B, Boesch C. Restoration of electrophysiological signals distorted by inductive effects of magnetic field gradients during MR sequences. Magn Reson Med 1999; 41:715-21. [PMID: 10332846 DOI: 10.1002/(sici)1522-2594(199904)41:4<715::aid-mrm9>3.0.co;2-7] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
A generally applicable method for almost complete suppression of signal artifacts on electrophysiological signals caused by B0-gradient switching (gradient noise) is presented. The method is demonstrated for electrocardiograms (ECGs) but can also be used for other electrophysiological signals. It takes advantage of the fact that under certain conditions, the effect of switching the B0-field gradient upon an electrophysiological signal can be modeled as a linear time-invariant system and fully characterized by pulse response functions. It is shown how the system's pulse response functions of the X, Y, and Z gradients can be determined and how gradient noise can be eliminated efficiently. The elimination of gradient noise by the proposed method causes in the current arrangement a constant delay of 128 msec, which is acceptable for patient monitoring and magnetic resonance sequence triggering.
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Affiliation(s)
- J Felblinger
- Department of MR Spectroscopy and Methodology, University of Berne, Switzerland.
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Felblinger J, Müri RM, Ozdoba C, Schroth G, Hess CW, Boesch C. Recordings of eye movements for stimulus control during fMRI by means of electro-oculographic methods. Magn Reson Med 1996; 36:410-4. [PMID: 8875411 DOI: 10.1002/mrm.1910360312] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
A method for monitoring eye movements in humans during functional MRI is presented. It is based on the acquisition of electro-oculographic (EOG) signals near one eye. EOG potentials were amplified and converted into an optical signal just outside the head coil. An optical fiber was used for signal transmission from inside the magnet bore to the control room. The EOG sensor was tested during EPI sequences at 1.5 Tesla without contamination of the MR signal. Some flow related artifacts on the EOG were observed inside the magnet, but no additional interactions from the MR sequence. An analysis of the latency, direction, and amplitude of the saccadic eye movements was possible.
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Affiliation(s)
- J Felblinger
- Department of MR Spectroscopy and Methodology, University of Bern, Switzerland
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26
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Felblinger J, Lehmann C, Boesch C. Electrocardiogram acquisition during MR examinations for patient monitoring and sequence triggering. Magn Reson Med 1994; 32:523-9. [PMID: 7997120 DOI: 10.1002/mrm.1910320416] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
We have developed a method for measuring the electrocardiogram (ECG) continuously during MR examinations. In contrast to ECG acquisition by wires, our new method is to amplify and convert the ECG into an optical signal directly above the patient's heart. The optical signal is transmitted out of the magnet bore by optical fiber. The small and fixed dimensions of the ECG amplifier avoid interactions with the MR system because of shorter electrical structures and smaller enclosed areas. Tests of the proposed device in a 1.5 Tesla MR system show that continuous and reliable ECG monitoring and sequence triggering are possible.
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Affiliation(s)
- J Felblinger
- MR Center, University and Inselspital, Berne, Switzerland
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Peden CJ, Menon DK, Hall AS, Sargentoni J, Whitwam JG. Magnetic resonance for the anaesthetist. Part II: Anaesthesia and monitoring in MR units. Anaesthesia 1992; 47:508-17. [PMID: 1616091 DOI: 10.1111/j.1365-2044.1992.tb02278.x] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Anaesthetists are increasingly involved in patient care during magnetic resonance imaging and spectroscopy. This paper describes a system which has been developed for the management of critically ill patients and the conduct of anaesthesia in a magnetic resonance unit with a 1.6 tesla whole body magnet. Difficulties which arise from working in a confined space in a high magnetic field are highlighted. Different approaches to anaesthesia, sedation and the modification of equipment for use in this environment are reviewed. The problems associated with patient monitoring within a magnetic field are discussed and some solutions are suggested. A transport system for critically ill patients is described and a protocol for management is outlined.
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