1
|
Kolandaivelu A, Bruce CG, Seemann F, Yildirim DK, Campbell-Washburn AE, Lederman RJ, Herzka DA. Evaluation of 12-lead electrocardiogram at 0.55T for improved cardiac monitoring in magnetic resonance imaging. J Cardiovasc Magn Reson 2024; 26:101009. [PMID: 38342406 PMCID: PMC10940178 DOI: 10.1016/j.jocmr.2024.101009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2023] [Revised: 01/28/2024] [Accepted: 02/06/2024] [Indexed: 02/13/2024] Open
Abstract
BACKGROUND The 12-lead electrocardiogram (ECG) is a standard diagnostic tool for monitoring cardiac ischemia and heart rhythm during cardiac interventional procedures and stress testing. These procedures can benefit from magnetic resonance imaging (MRI) information; however, the MRI scanner magnetic field leads to ECG distortion that limits ECG interpretation. This study evaluated the potential for improved ECG interpretation in a "low field" 0.55T MRI scanner. METHODS The 12-lead ECGs were recorded inside 0.55T, 1.5T, and 3T MRI scanners, as well as at scanner table "home" position in the fringe field and outside the scanner room (seven pigs). To assess interpretation of ischemic ECG changes in a 0.55T MRI scanner, ECGs were recorded before and after coronary artery occlusion (seven pigs). ECGs was also recorded for five healthy human volunteers in the 0.55T scanner. ECG error and variation were assessed over 2-minute recordings for ECG features relevant to clinical interpretation: the PR interval, QRS interval, J point, and ST segment. RESULTS ECG error was lower at 0.55T compared to higher field scanners. Only at 0.55T table home position, did the error approach the guideline recommended 0.025 mV ceiling for ECG distortion (median 0.03 mV). At scanner isocenter, only in the 0.55T scanner did J point error fall within the 0.1 mV threshold for detecting myocardial ischemia (median 0.03 mV in pigs and 0.06 mV in healthy volunteers). Correlation of J point deviation inside versus outside the 0.55T scanner following coronary artery occlusion was excellent at scanner table home position (r2 = 0.97), and strong at scanner isocenter (r2 = 0.92). CONCLUSION ECG distortion is improved in 0.55T compared to 1.5T and 3T MRI scanners. At scanner home position, ECG distortion at 0.55T is low enough that clinical interpretation appears feasible without need for more cumbersome patient repositioning. At 0.55T scanner isocenter, ST segment changes during coronary artery occlusion appear detectable but distortion is enough to obscure subtle ST segment changes that could be clinically relevant. Reduced ECG distortion in 0.55T scanners may simplify the problem of suppressing residual distortion by ECG cable positioning, averaging, and filtering and could reduce current restrictions on ECG monitoring during interventional MRI procedures.
Collapse
Affiliation(s)
- Aravindan Kolandaivelu
- Cardiovascular Branch, Division of Intramural Research, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA; Division of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Christopher G Bruce
- Cardiovascular Branch, Division of Intramural Research, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Felicia Seemann
- Cardiovascular Branch, Division of Intramural Research, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Dursun Korel Yildirim
- Cardiovascular Branch, Division of Intramural Research, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Adrienne E Campbell-Washburn
- Cardiovascular Branch, Division of Intramural Research, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Robert J Lederman
- Cardiovascular Branch, Division of Intramural Research, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA.
| | - Daniel A Herzka
- Cardiovascular Branch, Division of Intramural Research, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA; Department of Radiology, Case Western Reserve University and University Hospitals Cleveland Medical Center, Cleveland, Ohio, USA
| |
Collapse
|
2
|
Rogers T, Campbell-Washburn AE, Ramasawmy R, Yildirim DK, Bruce CG, Grant LP, Stine AM, Kolandaivelu A, Herzka DA, Ratnayaka K, Lederman RJ. Interventional cardiovascular magnetic resonance: state-of-the-art. J Cardiovasc Magn Reson 2023; 25:48. [PMID: 37574552 PMCID: PMC10424337 DOI: 10.1186/s12968-023-00956-7] [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: 02/11/2023] [Accepted: 07/25/2023] [Indexed: 08/15/2023] Open
Abstract
Transcatheter cardiovascular interventions increasingly rely on advanced imaging. X-ray fluoroscopy provides excellent visualization of catheters and devices, but poor visualization of anatomy. In contrast, magnetic resonance imaging (MRI) provides excellent visualization of anatomy and can generate real-time imaging with frame rates similar to X-ray fluoroscopy. Realization of MRI as a primary imaging modality for cardiovascular interventions has been slow, largely because existing guidewires, catheters and other devices create imaging artifacts and can heat dangerously. Nonetheless, numerous clinical centers have started interventional cardiovascular magnetic resonance (iCMR) programs for invasive hemodynamic studies or electrophysiology procedures to leverage the clear advantages of MRI tissue characterization, to quantify cardiac chamber function and flow, and to avoid ionizing radiation exposure. Clinical implementation of more complex cardiovascular interventions has been challenging because catheters and other tools require re-engineering for safety and conspicuity in the iCMR environment. However, recent innovations in scanner and interventional device technology, in particular availability of high performance low-field MRI scanners could be the inflection point, enabling a new generation of iCMR procedures. In this review we review these technical considerations, summarize contemporary clinical iCMR experience, and consider potential future applications.
Collapse
Affiliation(s)
- Toby Rogers
- Cardiovascular Branch, Division of Intramural Research, National Heart, Lung, and Blood Institute, National Institutes of Health, Building 10/Room 2C713, 9000 Rockville Pike, Bethesda, MD, 20892-1538, USA.
- Section of Interventional Cardiology, MedStar Washington Hospital Center, 110 Irving St NW, Suite 4B01, Washington, DC, 20011, USA.
| | - Adrienne E Campbell-Washburn
- Cardiovascular Branch, Division of Intramural Research, National Heart, Lung, and Blood Institute, National Institutes of Health, Building 10/Room 2C713, 9000 Rockville Pike, Bethesda, MD, 20892-1538, USA
| | - Rajiv Ramasawmy
- Cardiovascular Branch, Division of Intramural Research, National Heart, Lung, and Blood Institute, National Institutes of Health, Building 10/Room 2C713, 9000 Rockville Pike, Bethesda, MD, 20892-1538, USA
| | - D Korel Yildirim
- Cardiovascular Branch, Division of Intramural Research, National Heart, Lung, and Blood Institute, National Institutes of Health, Building 10/Room 2C713, 9000 Rockville Pike, Bethesda, MD, 20892-1538, USA
| | - Christopher G Bruce
- Cardiovascular Branch, Division of Intramural Research, National Heart, Lung, and Blood Institute, National Institutes of Health, Building 10/Room 2C713, 9000 Rockville Pike, Bethesda, MD, 20892-1538, USA
| | - Laurie P Grant
- Cardiovascular Branch, Division of Intramural Research, National Heart, Lung, and Blood Institute, National Institutes of Health, Building 10/Room 2C713, 9000 Rockville Pike, Bethesda, MD, 20892-1538, USA
| | - Annette M Stine
- Cardiovascular Branch, Division of Intramural Research, National Heart, Lung, and Blood Institute, National Institutes of Health, Building 10/Room 2C713, 9000 Rockville Pike, Bethesda, MD, 20892-1538, USA
| | - Aravindan Kolandaivelu
- Cardiovascular Branch, Division of Intramural Research, National Heart, Lung, and Blood Institute, National Institutes of Health, Building 10/Room 2C713, 9000 Rockville Pike, Bethesda, MD, 20892-1538, USA
- Johns Hopkins Hospital, Baltimore, MD, USA
| | - Daniel A Herzka
- Cardiovascular Branch, Division of Intramural Research, National Heart, Lung, and Blood Institute, National Institutes of Health, Building 10/Room 2C713, 9000 Rockville Pike, Bethesda, MD, 20892-1538, USA
| | - Kanishka Ratnayaka
- Cardiovascular Branch, Division of Intramural Research, National Heart, Lung, and Blood Institute, National Institutes of Health, Building 10/Room 2C713, 9000 Rockville Pike, Bethesda, MD, 20892-1538, USA
- Rady Children's Hospital, San Diego, CA, USA
| | - Robert J Lederman
- Cardiovascular Branch, Division of Intramural Research, National Heart, Lung, and Blood Institute, National Institutes of Health, Building 10/Room 2C713, 9000 Rockville Pike, Bethesda, MD, 20892-1538, USA.
| |
Collapse
|
3
|
Oebel S, Jahnke C, Hindricks G, Paetsch I. Nutzen der kardialen Magnetresonanzdiagnostik für Patienten mit Herzrhythmusstörungen. Herz 2022; 47:110-117. [DOI: 10.1007/s00059-022-05105-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/02/2022] [Indexed: 11/28/2022]
|
4
|
Schmidt EJ, Elahi H, Meyer ES, Baumgaertner R, Neri L, Berger RD, Tandri H, Hunter DW, Cohen SP, Oberdier MT, Halperin HR. Reduced Motion External Defibrillation (RMD): Reduced Subject Motion with Equivalent Defibrillation Efficiency validated in Swine. Heart Rhythm 2022; 19:1165-1173. [PMID: 35240311 DOI: 10.1016/j.hrthm.2022.02.021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 02/21/2022] [Accepted: 02/23/2022] [Indexed: 12/12/2022]
Abstract
BACKGROUND External defibrillators are used for arrhythmia cardioversion and for defibrillating during cardiac arrest. During defibrillation, short-duration Biphasic pulses cause intense motion due to rapid chest-wall muscle contraction. A reduced-motion external defibrillator (RMD) was constructed by integrating a commercial defibrillator with a Tetanizing-waveform generator. A long-duration low-amplitude Tetanizing-waveform slowly stimulated the chest musculature prior to the Biphasic pulse, reducing muscle contraction during the shock. OBJECTIVE Evaluate RMD defibrillation in swine for subject-motion during defibrillation pulses and for defibrillation effectiveness. RMD defibrillation can reduce the duration of arrhythmia ablation-therapy or simplify cardioversion procedures. METHODS The Tetanizing unit delivered a triangular 1-kHz pulse of 0.25-2.0sec duration and 10-100Volt peak amplitude, subsequently triggering the conventional defibrillator to output standard 1-200J energy Biphasic pulses at the next R-wave. Forward-limb motion was evaluated by measuring Peak Acceleration and Limb Work during RMD (Tetanizing+Biphasic) or Biphasic-pulse-only waveforms at 10-3sec sampling-rate. Seven swine were arrested electrically and subsequently defibrillated. Biphasic-pulse-only and RMD defibrillations were repeated 25-35 times/swine, varying Tetanizing parameters and the Biphasic-pulse energy. Defibrillation thresholds (DFTs) were established by measuring the minimum energy required to restore sinus-rhythm with Biphasic-pulse-only or RMD defibrillations. RESULTS Two forward-limb acceleration-peaks occurred during both the Tetanizing-waveform and Biphasic-pulse, indicating rapid and slower nociceptic (pain-sensation) nerve-fiber activation. Optimal RMD Tetanizing-parameters (25-35V, 0.25-0.75sec duration), relative to Biphasic-pulse-only defibrillations, resulted in 74+10% smaller Peak Accelerations and 85+10% reduced Limb Work. DFT energies were identical, comparing RMD to Biphasic-pulse-only defibrillations. CONCLUSION Relative to conventional defibrillations, RMD defibrillations maintain rhythm-restoration efficiency with drastically reduced subject-motion.
Collapse
Affiliation(s)
- Ehud J Schmidt
- Medicine (Cardiology), Johns Hopkins University, Baltimore, MD.
| | - Hassan Elahi
- Medicine (Cardiology), Johns Hopkins University, Baltimore, MD
| | - Eric S Meyer
- Medicine (Cardiology), Johns Hopkins University, Baltimore, MD
| | | | - Luca Neri
- Medicine (Cardiology), Johns Hopkins University, Baltimore, MD
| | - Ronald D Berger
- Medicine (Cardiology), Johns Hopkins University, Baltimore, MD
| | | | - David W Hunter
- Medicine (Cardiology), Johns Hopkins University, Baltimore, MD
| | | | - Matt T Oberdier
- Medicine (Cardiology), Johns Hopkins University, Baltimore, MD
| | | |
Collapse
|
5
|
Bauer BK, Meier C, Bietenbeck M, Lange PS, Eckardt L, Yilmaz A. Cardiovascular Magnetic Resonance-Guided Radiofrequency Ablation: Where Are We Now? JACC Clin Electrophysiol 2022; 8:261-274. [PMID: 35210090 DOI: 10.1016/j.jacep.2021.11.017] [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: 08/17/2021] [Revised: 11/08/2021] [Accepted: 11/17/2021] [Indexed: 11/16/2022]
Abstract
The possibilities of cardiovascular magnetic resonance (CMR) imaging for myocardial tissue characterization and catheter ablation guidance are accompanied by some fictional concepts. In this review, we present the available facts about CMR-guided catheter ablation procedures as well as promising, however unproven, theoretical concepts. CMR promises to visualize the respective arrhythmogenic substrate and may thereby make it more localizable for electrophysiology (EP)-based ablation. Robust CMR imaging is challenged by motion of the heart resulting from cardiac and respiratory cycles. In contrast to conventional "passive" tracking of the catheter tip by real-time CMR, novel approaches based on "active" tracking are performed by integrating microcoils into the catheter tip that send a receiver signal. Several experimental and clinical studies were already performed based on real-time CMR for catheter ablation of atrial and ventricular arrhythmias. Importantly, successful ablation of the cavotricuspid isthmus was already performed in patients with typical atrial flutter. However, a complete EP procedure with real-time CMR-guided transseptal puncture and subsequent pulmonary vein isolation has not been shown so far in patients with atrial fibrillation. Moreover, real-time CMR-guided EP for ventricular tachycardia ablation was only performed in animal models using a transseptal, retrograde, or epicardial access-but not in humans. Essential improvements within the next few years regarding basic technical requirements, such as higher spatial and temporal resolution of real-time CMR imaging as well as clinically approved cardiac magnetic resonance-conditional defibrillators, are ultimately required-but can also be expected-and will move this field forward.
Collapse
Affiliation(s)
- Bastian Klemens Bauer
- Department of Cardiology II - Electrophysiology, University Hospital Münster, Münster, Germany
| | - Claudia Meier
- Department of Cardiology, Division of Cardiovascular Imaging, University Hospital Münster, Münster, Germany
| | - Michael Bietenbeck
- Department of Cardiology, Division of Cardiovascular Imaging, University Hospital Münster, Münster, Germany
| | - Philipp Sebastian Lange
- Department of Cardiology II - Electrophysiology, University Hospital Münster, Münster, Germany
| | - Lars Eckardt
- Department of Cardiology II - Electrophysiology, University Hospital Münster, Münster, Germany
| | - Ali Yilmaz
- Department of Cardiology, Division of Cardiovascular Imaging, University Hospital Münster, Münster, Germany.
| |
Collapse
|
6
|
Rier SC, Vreemann S, Nijhof WH, van Driel VJHM, van der Bilt IAC. Interventional cardiac magnetic resonance imaging: current applications, technology readiness level, and future perspectives. Ther Adv Cardiovasc Dis 2022; 16:17539447221119624. [PMID: 36039865 PMCID: PMC9434707 DOI: 10.1177/17539447221119624] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
BACKGROUND Cardiac magnetic resonance (CMR) provides excellent temporal and spatial resolution, tissue characterization, and flow measurements. This enables major advantages when guiding cardiac invasive procedures compared with X-ray fluoroscopy or ultrasound guidance. However, clinical implementation is limited due to limited availability of technological advancements in magnetic resonance imaging (MRI) compatible equipment. A systematic review of the available literature on past and present applications of interventional MR and its technology readiness level (TRL) was performed, also suggesting future applications. METHODS A structured literature search was performed using PubMed. Search terms were focused on interventional CMR, cardiac catheterization, and other cardiac invasive procedures. All search results were screened for relevance by language, title, and abstract. TRL was adjusted for use in this article, level 1 being in a hypothetical stage and level 9 being widespread clinical translation. The papers were categorized by the type of procedure and the TRL was estimated. RESULTS Of 466 papers, 117 papers met the inclusion criteria. TRL was most frequently estimated at level 5 meaning only applicable to in vivo animal studies. Diagnostic right heart catheterization and cavotricuspid isthmus ablation had the highest TRL of 8, meaning proven feasibility and efficacy in a series of humans. CONCLUSION This article shows that interventional CMR has a potential widespread application although clinical translation is at a modest level with TRL usually at 5. Future development should be directed toward availability of MR-compatible equipment and further improvement of the CMR techniques. This could lead to increased TRL of interventional CMR providing better treatment.
Collapse
Affiliation(s)
- Sophie C Rier
- Cardiology Division, Department of Cardiology, Haga Teaching Hospital, Els Borst-Eilersplein 275, Postbus 40551, The Hague 2504 LN, The Netherlands
| | - Suzan Vreemann
- Department of Cardiology, Haga Teaching Hospital, The Hague, The Netherlands Siemens Healthineers Nederland B.V., Den Haag, The Netherlands
| | - Wouter H Nijhof
- Siemens Healthineers Nederland B.V., Den Haag, The Netherlands
| | | | | |
Collapse
|
7
|
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.
Collapse
|
8
|
Zou L, Hu J, Xu J, Wang H, Zheng H, Liu X. MHD signal derived Auto Variable Velocity Encoding for 2D Flow Imaging in 3T Cardiac Magnetic Resonance Imaging. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2021; 2021:4056-4059. [PMID: 34892120 DOI: 10.1109/embc46164.2021.9630504] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
To develop a novel technique to set variable velocity-encoding (VENC) values according to magnetohydrodynamic (MHD) voltage/signal for 2D flow imaging in 3 Tesla MR system. MHD signal is calculated using the electrocardiogram signals measured outside and inside the static magnetic bore during the patient preparation process. Then, VENC values are assigned in terms of the MHD signal in each cardiac phase. A volunteer was scanned to evaluate the feasibility of the proposed method. Specifically, velocity and velocity to noise ratio (VNR) using the proposed method were measured and compared with conventional constant VENC value methods at 3T. MHD signal is measured during the patient preparation, thus no additional breath-holds are required and the VENC values can be calculated for each cardiac phase before the acquisition.
Collapse
|
9
|
Mandal R, Budde R, Lawlor GL, Irazoqui P. Utilizing multimodal imaging to visualize potential mechanism for sudden death in epilepsy. Epilepsy Behav 2021; 122:108124. [PMID: 34237676 PMCID: PMC8429091 DOI: 10.1016/j.yebeh.2021.108124] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Revised: 05/20/2021] [Accepted: 05/31/2021] [Indexed: 12/28/2022]
Abstract
Sudden death in epilepsy or SUDEP is a fatal condition that accounts for more than 4000 deaths each year. Limited clinical and preclinical data on sudden death suggest critical contributions from autonomic, cardiac, and respiratory pathways. A potential mechanism for such sudden and severe cardiorespiratory dysregulation may be linked to acid reflux-induced laryngospasm. Here, we expand on our previous investigations and utilize a novel multimodal approach to provide visual evidence of acid reflux-initiated cardiorespiratory distress and subsequent sudden death in seizing rats. We used systemic kainic acid to acutely induce seizure activity in Long Evans rats, under urethane anesthesia. We recorded electroencephalography (EEG), electrocardiography (ECG), chest plethysmography, and esophageal pH signals through a multimodal recording platform, during simultaneous fast MRI scans of the rat stomach and esophagus. MRI images, in correlation with electrophysiology data were used to identify seizure progression, stomach acid movement up the esophagus, cardiorespiratory changes, and sudden death. In all cases of sudden death, esophageal pH recordings alongside MRI images visualized stomach acid movement up the esophagus. Severe cardiac (ST segment elevation), respiratory (intermittent apnea) and brain activity (EEG narrowing due to hypoxia) changes were observed only after acid reached larynx, which strongly suggested onset of laryngospasm following acid reflux. The complementary information coming from electrophysiology and fast MRI scans provided insight into the mechanism of esophageal reflux, laryngospasm, obstructive apnea, and subsequent sudden death in seizing animals. The results carry clinical significance as it outlines a potential mechanism that may be relevant to SUDEP in humans.
Collapse
Affiliation(s)
| | - Ryan Budde
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, USA
| | - Georgia L. Lawlor
- School of Electrical and Computer Engineering, Purdue University, West Lafayette, IN, USA
| | - Pedro Irazoqui
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, USA,School of Electrical and Computer Engineering, Purdue University, West Lafayette, IN, USA
| |
Collapse
|
10
|
Dos Reis JE, Odille F, Petitmangin G, Guillou A, Vuissoz PA, Felblinger J, Oster J. Broadband electrocardiogram acquisition for improved suppression of MRI gradient artifacts. Physiol Meas 2020; 41:045004. [PMID: 32120353 DOI: 10.1088/1361-6579/ab7b8e] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
OBJECTIVE Despite being routinely acquired during MRI examinations for triggering or monitoring purposes, electrocardiogram (ECG) signal recording and analysis remain challenging due to the inherent magnetic environment of an MRI scanner. The ECG signals are particularly distorted by the induction of electrical fields in the body by the MRI gradients. In this study, we propose a new hardware and software solution for the acquisition of ECG signal during MRI up to 3 T. APPROACH Instead of restricting the sensor bandwidth to limit these gradient artifacts, the new sensor architecture has a higher bandwidth, higher sampling frequency and larger input dynamics, in order to acquire the ECG signals and the gradient artifacts more precisely. Signal processing based on a novel detection algorithm and blanking are then applied for improved artifact suppression. MAIN RESULTS The proposed sensor allows the gradient artifacts to be acquired more precisely, and these artifacts are recorded with peak-to-peak amplitudes two orders of magnitude larger than for QRS complexes. The proposed method outperforms a state-of-the-art approach both in terms of signal quality (+9% 'SNR') and accuracy of QRS detection (+11%). SIGNIFICANCE The proposed hardware and software solutions open the way for the acquisition of high-quality of ECG gating in MRI, and improved diagnostic quality of ECG signals in MRI.
Collapse
|
11
|
Mukherjee RK, Costa CM, Neji R, Harrison JL, Sim I, Williams SE, Whitaker J, Chubb H, O'Neill L, Schneider R, Lloyd T, Pohl T, Roujol S, Niederer SA, Razavi R, O'Neill MD. Evaluation of a real-time magnetic resonance imaging-guided electrophysiology system for structural and electrophysiological ventricular tachycardia substrate assessment. Europace 2019; 21:1432-1441. [PMID: 31219547 PMCID: PMC6735875 DOI: 10.1093/europace/euz165] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Accepted: 05/22/2019] [Indexed: 11/21/2022] Open
Abstract
Aims Potential advantages of real-time magnetic resonance imaging (MRI)-guided electrophysiology (MR-EP) include contemporaneous three-dimensional substrate assessment at the time of intervention, improved procedural guidance, and ablation lesion assessment. We evaluated a novel real-time MR-EP system to perform endocardial voltage mapping and assessment of delayed conduction in a porcine ischaemia–reperfusion model. Methods and results Sites of low voltage and slow conduction identified using the system were registered and compared to regions of late gadolinium enhancement (LGE) on MRI. The Sorensen–Dice similarity coefficient (DSC) between LGE scar maps and voltage maps was computed on a nodal basis. A total of 445 electrograms were recorded in sinus rhythm (range: 30–186) using the MR-EP system including 138 electrograms from LGE regions. Pacing captured at 103 sites; 47 (45.6%) sites had a stimulus-to-QRS (S-QRS) delay of ≥40 ms. Using conventional (0.5–1.5 mV) bipolar voltage thresholds, the sensitivity and specificity of voltage mapping using the MR-EP system to identify MR-derived LGE was 57% and 96%, respectively. Voltage mapping had a better predictive ability in detecting LGE compared to S-QRS measurements using this system (area under curve: 0.907 vs. 0.840). Using an electrical threshold of 1.5 mV to define abnormal myocardium, the total DSC, scar DSC, and normal myocardium DSC between voltage maps and LGE scar maps was 79.0 ± 6.0%, 35.0 ± 10.1%, and 90.4 ± 8.6%, respectively. Conclusion Low-voltage zones and regions of delayed conduction determined using a real-time MR-EP system are moderately associated with LGE areas identified on MRI.
Collapse
Affiliation(s)
- Rahul K Mukherjee
- School of Biomedical Engineering and Imaging Sciences, King's College London, 4th Floor, North Wing, St Thomas' Hospital, London, UK
| | - Caroline Mendonca Costa
- School of Biomedical Engineering and Imaging Sciences, King's College London, 4th Floor, North Wing, St Thomas' Hospital, London, UK
| | - Radhouene Neji
- School of Biomedical Engineering and Imaging Sciences, King's College London, 4th Floor, North Wing, St Thomas' Hospital, London, UK.,Siemens Healthcare, Sir William Siemens Square, Frimley, Camberley, UK
| | - James L Harrison
- School of Biomedical Engineering and Imaging Sciences, King's College London, 4th Floor, North Wing, St Thomas' Hospital, London, UK.,Department of Cardiology, King's College Hospital NHS Foundation Trust, London, UK
| | - Iain Sim
- School of Biomedical Engineering and Imaging Sciences, King's College London, 4th Floor, North Wing, St Thomas' Hospital, London, UK
| | - Steven E Williams
- School of Biomedical Engineering and Imaging Sciences, King's College London, 4th Floor, North Wing, St Thomas' Hospital, London, UK.,Department of Cardiology, Guy's and St Thomas' NHS Foundation Trust, London, UK
| | - John Whitaker
- School of Biomedical Engineering and Imaging Sciences, King's College London, 4th Floor, North Wing, St Thomas' Hospital, London, UK
| | - Henry Chubb
- School of Biomedical Engineering and Imaging Sciences, King's College London, 4th Floor, North Wing, St Thomas' Hospital, London, UK
| | - Louisa O'Neill
- School of Biomedical Engineering and Imaging Sciences, King's College London, 4th Floor, North Wing, St Thomas' Hospital, London, UK
| | | | - Tom Lloyd
- Imricor Medical Systems, 400 Gateway Blvd, MN, USA
| | | | - Sébastien Roujol
- School of Biomedical Engineering and Imaging Sciences, King's College London, 4th Floor, North Wing, St Thomas' Hospital, London, UK
| | - Steven A Niederer
- School of Biomedical Engineering and Imaging Sciences, King's College London, 4th Floor, North Wing, St Thomas' Hospital, London, UK
| | - Reza Razavi
- School of Biomedical Engineering and Imaging Sciences, King's College London, 4th Floor, North Wing, St Thomas' Hospital, London, UK
| | - Mark D O'Neill
- School of Biomedical Engineering and Imaging Sciences, King's College London, 4th Floor, North Wing, St Thomas' Hospital, London, UK.,Department of Cardiology, Guy's and St Thomas' NHS Foundation Trust, London, UK
| |
Collapse
|
12
|
Shusterman V, Nagpal P, Thedens D, Zhu X, Matasic DS, Yoon JY, Morgan G, Hoffman S, London B. Magnetic Resonance Imaging of Contracting Ultrathin Cardiac Tissue. Biomed Phys Eng Express 2019; 5:045003. [PMID: 32733693 PMCID: PMC7392236 DOI: 10.1088/2057-1976/ab1c1c] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
OBJECTIVE Integrating cardiac-tissue patches into the beating heart and evaluating the long-term effects of such integration on cardiac contractility are two challenges in an emerging field of regenerative medicine. This pilot study presents tools for the imaging of contracting multicellular cardiac tissue constructs (MTCs) in vitro and demonstrates the feasibility of tracking the early development of strand geometry and contractions in ultrathin strands and layers of cardiac tissue using CINE MRI. APPROACH Cultured, ultrathin (~50-100-micron) MTCs of rat neonatal cardiomyocytes were plated in rectangular cell chambers (4.5 × 2.0 cm) with and without ultrathin, carbon EP electrodes embedded in the floor of the cell chamber. Two-dimensional, steady-state free precession (SSFP) CINE MRI, cell microscopy, and tissue photography were performed on Days 5-9 of cell development. Potential confounders and MRI artifacts were evaluated using non-contracting cardiac tissues and cell-free chambers filled with the cell-culture medium. MAIN RESULTS Synchronized contractions formed by Day 7; individual contracting tissue strands became identifiable by Day 9. The global patterns and details of the strand geometry and movement patterns in the SSFP images were in excellent agreement with microscopic and photographic images. No synchronized movement was identifiable by either microscopy or CINE MRI in the non-contracting MTCs or the cell-free medium. The EP recordings revealed well-defined depolarization and repolarization waveforms; the imaging artifacts generated by the carbon electrodes were small. SIGNIFICANCE This pilot study demonstrates the feasibility of imaging cardiac-strand patterns and contractile activity in ultrathin, two-dimensional cardiac tissue in commonly used clinical scanners.
Collapse
|
13
|
Dos Reis JE, Soullié P, Oster J, Palmero Soler E, Petitmangin G, Felblinger J, Odille F. Reconstruction of the 12-lead ECG using a novel MR-compatible ECG sensor network. Magn Reson Med 2019; 82:1929-1945. [PMID: 31199011 DOI: 10.1002/mrm.27854] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Revised: 05/06/2019] [Accepted: 05/21/2019] [Indexed: 11/05/2022]
Abstract
PURPOSE Current electrocardiography (ECG) devices in MRI use non-conventional electrode placement, have a narrow bandwidth, and suffer from signal distortions including magnetohydrodynamic (MHD) effects and gradient-induced artifacts. In this work a system is proposed to obtain a high-quality 12-lead ECG. METHODS A network of N electrically independent MR-compatible ECG sensors was developed (N = 4 in this study). Each sensor uses a safe technology - short cables, preamplification/digitization close to the patient, and optical transmission - and provides three bipolar voltage leads. A matrix combination is applied to reconstruct a 12-lead ECG from the raw network signals. A subject-specific calibration is performed to identify the matrix coefficients, maximizing the similarity with a true 12-lead ECG, acquired with a conventional 12-lead device outside the scan room. The sensor network was subjected to radiofrequency heating phantom tests at 3T. It was then tested in four subjects, both at 1.5T and 3T. RESULTS Radiofrequency heating at 3T was within the MR-compatibility standards. The reconstructed 12-lead ECG showed minimal MHD artifacts and its morphology compared well with that of the true 12-lead ECG, as measured by correlation coefficients above 93% (respectively, 84%) for the QRS complex shape during steady-state free precession (SSFP) imaging at 1.5T (respectively, 3T). CONCLUSION High-quality 12-lead ECG can be reconstructed by the proposed sensor network at 1.5T and 3T with reduced MHD artifacts compared to previous systems. The system might help improve patient monitoring and triggering and might also be of interest for interventional MRI and advanced cardiac MR applications.
Collapse
Affiliation(s)
- Jesús E Dos Reis
- IADI, INSERM and Université de Lorraine, Nancy, France.,Schiller Medical SAS, Wissembourg, France
| | - Paul Soullié
- IADI, INSERM and Université de Lorraine, Nancy, France
| | - Julien Oster
- IADI, INSERM and Université de Lorraine, Nancy, France
| | | | | | - Jacques Felblinger
- IADI, INSERM and Université de Lorraine, Nancy, France.,CIC-IT 1433, INSERM, Université de Lorraine and CHRU Nancy, Nancy, France
| | - Freddy Odille
- IADI, INSERM and Université de Lorraine, Nancy, France.,CIC-IT 1433, INSERM, Université de Lorraine and CHRU Nancy, Nancy, France
| |
Collapse
|
14
|
Gregory TS, Murrow JR, Oshinski JN, Tse ZTH. Exploring magnetohydrodynamic voltage distributions in the human body: Preliminary results. PLoS One 2019; 14:e0213235. [PMID: 30840694 PMCID: PMC6402669 DOI: 10.1371/journal.pone.0213235] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2017] [Accepted: 02/19/2019] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND The aim of this study was to noninvasively measure regional contributions of vasculature in the human body using magnetohydrodynamic voltages (VMHD) obtained from electrocardiogram (ECG) recordings performed inside MRI's static magnetic field (B0). Integrating the regional VMHD over the Swave-Twave segment of the cardiac cycle (Vsegment) provides a non-invasive method for measuring regional blood volumes, which can be rapidly obtained during MRI without incurring additional cost. METHODS VMHD was extracted from 12-lead ECG traces acquired during gradual introduction into a 3T MRI. Regional contributions were computed utilizing weights based on B0's strength at specified distances from isocenter. Vsegment mapping was performed in six subjects and validated against MR angiograms (MRA). RESULTS Fluctuations in Vsegment, which presented as positive trace deflections, were found to be associated with aortic-arch flow in the thoracic cavity, the main branches of the abdominal aorta, and the bifurcation of the common iliac artery. The largest fluctuation corresponded to the location where the aortic arch was approximately orthogonal to B0. The smallest fluctuations corresponded to areas of vasculature that were parallel to B0. Significant correlations (specifically, Spearman's ranked correlation coefficients of 0.96 and 0.97 for abdominal and thoracic cavities, respectively) were found between the MRA and Vsegment maps (p < 0.001). CONCLUSIONS A novel non-invasive method to extract regional blood volumes from ECGs was developed and shown to be a rapid means to quantify peripheral and abdominal blood volumes.
Collapse
Affiliation(s)
- T. Stan Gregory
- College of Engineering, University of Georgia, Athens, Georgia, United States of America
| | - Jonathan R. Murrow
- AU/UGA Medical Partnership, University of Georgia, Athens, Georgia, United States of America
| | - John N. Oshinski
- Department of Radiology and Imaging Sciences, Emory University, Atlanta, Georgia, United States of America
| | - Zion Tsz Ho Tse
- School of Electrical and Computer Engineering, University of Georgia, Athens, Georgia, United States of America
- * E-mail:
| |
Collapse
|
15
|
Mukherjee RK, Chubb H, Roujol S, Razavi R, O'Neill MD. Advances in Real-Time MRI-Guided Electrophysiology. CURRENT CARDIOVASCULAR IMAGING REPORTS 2019; 12:6. [PMID: 31501689 PMCID: PMC6733706 DOI: 10.1007/s12410-019-9481-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Purpose of Review Theoretical benefits of real-time MRI guidance over conventional electrophysiology include contemporaneous 3D substrate assessment and accurate intra-procedural guidance and evaluation of ablation lesions. We review the unique challenges inherent to MRI-guided electrophysiology and how to translate the potential benefits in the treatment of cardiac arrhythmias. Recent Findings Over the last 5 years, there has been substantial progress, initially in animal models and more recently in clinical studies, to establish methods and develop workflows within the MR environment that resemble those of conventional electrophysiology laboratories. Real-time MRI-guided systems have been used to perform electroanatomic mapping and ablation in patients with atrial flutter, and there is interest in developing the technology to tackle more complex arrhythmias including atrial fibrillation and ventricular tachycardia. Summary Mainstream adoption of real-time MRI-guided electrophysiology will require demonstration of clinical benefit and will be aided by increased availability of devices suitable for use in the MRI environment.
Collapse
Affiliation(s)
- Rahul K Mukherjee
- School of Biomedical Engineering and Imaging Sciences, King's College London, 4th Floor, North Wing, St Thomas' Hospital, London SE1 7EH, UK
| | - Henry Chubb
- School of Biomedical Engineering and Imaging Sciences, King's College London, 4th Floor, North Wing, St Thomas' Hospital, London SE1 7EH, UK
| | - Sébastien Roujol
- School of Biomedical Engineering and Imaging Sciences, King's College London, 4th Floor, North Wing, St Thomas' Hospital, London SE1 7EH, UK
| | - Reza Razavi
- School of Biomedical Engineering and Imaging Sciences, King's College London, 4th Floor, North Wing, St Thomas' Hospital, London SE1 7EH, UK
| | - Mark D O'Neill
- School of Biomedical Engineering and Imaging Sciences, King's College London, 4th Floor, North Wing, St Thomas' Hospital, London SE1 7EH, UK.,Department of Cardiology, King's College Hospital NHS Foundation Trust, London, UK
| |
Collapse
|
16
|
Nedoma J, Fajkus M, Martinek R, Nazeran H. Vital Sign Monitoring and Cardiac Triggering at 1.5 Tesla: A Practical Solution by an MR-Ballistocardiography Fiber-Optic Sensor. SENSORS 2019; 19:s19030470. [PMID: 30682784 PMCID: PMC6386836 DOI: 10.3390/s19030470] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Revised: 01/11/2019] [Accepted: 01/21/2019] [Indexed: 12/21/2022]
Abstract
This article presents a solution for continuous monitoring of both respiratory rate (RR) and heart rate (HR) inside Magnetic Resonance Imaging (MRI) environments by a novel ballistocardiography (BCG) fiber-optic sensor. We designed and created a sensor based on the Fiber Bragg Grating (FBG) probe encapsulated inside fiberglass (fiberglass is a composite material made up of glass fiber, fabric, and cured synthetic resin). Due to this, the encapsulation sensor is characterized by very small dimensions (30 × 10 × 0.8 mm) and low weight (2 g). We present original results of real MRI measurements (conventionally most used 1.5 T MR scanner) involving ten volunteers (six men and four women) by performing conventional electrocardiography (ECG) to measure the HR and using a Pneumatic Respiratory Transducer (PRT) for RR monitoring. The acquired sensor data were compared against real measurements using the objective Bland–Altman method, and the functionality of the sensor was validated (95.36% of the sensed values were within the ±1.96 SD range for the RR determination and 95.13% of the values were within the ±1.96 SD range for the HR determination) by this means. The accuracy of this sensor was further characterized by a relative error below 5% (4.64% for RR and 4.87% for HR measurements). The tests carried out in an MRI environment demonstrated that the presence of the FBG sensor in the MRI scanner does not affect the quality of this imaging modality. The results also confirmed the possibility of using the sensor for cardiac triggering at 1.5 T (for synchronization and gating of cardiovascular magnetic resonance) and for cardiac triggering when a Diffusion Weighted Imaging (DWI) is used.
Collapse
Affiliation(s)
- Jan Nedoma
- Department of Telecommunications, Faculty of Electrical Engineering and Computer Science, VSB-Technical University of Ostrava, 17 Listopadu 15, 70833 Ostrava, Czech Republic.
| | - Marcel Fajkus
- Department of Telecommunications, Faculty of Electrical Engineering and Computer Science, VSB-Technical University of Ostrava, 17 Listopadu 15, 70833 Ostrava, Czech Republic.
| | - Radek Martinek
- Department of Cybernetics and Biomedical Engineering, Faculty of Electrical Engineering and Computer Science, VSB-Technical University of Ostrava, 17 Listopadu 15, 70833 Ostrava, Czech Republic.
| | - Homer Nazeran
- Department of Metallurgical, Materials and Biomedical Engineering, University of Texas El Paso, 500 W University Ave, El Paso, TX 79968, USA.
| |
Collapse
|
17
|
Mandal R, Babaria N. Adaptive and Wireless Recordings of Electrophysiological Signals During Concurrent Magnetic Resonance Imaging. IEEE Trans Biomed Eng 2018; 66:1649-1657. [PMID: 30369431 DOI: 10.1109/tbme.2018.2877640] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Strong electromagnetic fields that occur during functional magnetic resonance imaging (fMRI) presents a challenging environment for concurrent electrophysiological recordings. Here, we present a miniaturized, wireless platform-"MR-Link" (Multimodal Recording Link) that provides a hardware solution for simultaneous electrophysiological and fMRI signal acquisition. The device detects the changes in the electromagnetic field during fMRI to synchronize amplification and sampling of electrophysiological signals with minimal artifacts. It wirelessly transmits the recorded data at a frequency detectable by the MR-receiver coil. The transmitted data is readily separable from MRI in the frequency domain. To demonstrate its efficacy, we used this device to record electrocardiograms and somatosensory evoked potential during concurrent fMRI scans. The device minimized the fMRI-induced artifacts in electrophysiological data and wirelessly transmitted the data back to the receiver coil without compromising the fMRI signal quality. The device is compact (22 mm dia., 2 gms) and can be placed within the MRI bore to precisely synchronize with fMRI. Therefore, MR-Link offers an inexpensive system by eliminating the need for amplifiers with a high dynamic range, high-speed sampling, additional storage, or synchronization hardware for electrophysiological signal acquisition. It is expected to enable a broader range of applications of simultaneous fMRI and electrophysiology in animals and humans.
Collapse
|
18
|
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.
Collapse
|
19
|
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
|
20
|
Wu KJ, Gregory TS, Boland BL, Zhao W, Cheng R, Mao L, Tse ZTH. Magnetic resonance conditional paramagnetic choke for suppression of imaging artifacts during magnetic resonance imaging. Proc Inst Mech Eng H 2018; 232:597-604. [PMID: 29687748 DOI: 10.1177/0954411918771098] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Higher risk patient populations require continuous physiological monitoring and, in some cases, connected life-support systems, during magnetic resonance imaging examinations. While recently there has been a shift toward wireless technology, some of the magnetic resonance imaging devices are still connected to the outside using cabling that could interfere with the magnetic resonance imaging's radio frequency during scanning, resulting in excessive heating. We developed a passive method for radio frequency suppression on cabling that may assist in making some of these devices magnetic resonance imaging compatible. A barrel-shaped strongly paramagnetic choke was developed to suppress induced radio frequency signals which are overlaid onto physiological monitoring leads during magnetic resonance imaging. It utilized a choke placed along the signal lines, with a gadolinium solution core. The choke's magnetic susceptibility was modeled, for a given geometric design, at increasing chelate concentration levels, and measured using a vibrating sample magnetometer. Radio frequency noise suppression versus frequency was quantified with network-analyzer measurements and tested using cabling placed in the magnetic resonance imaging scanner. Temperature-elevation and image-quality reduction due to the device were measured using American Society for Testing and Materials phantoms. Prototype chokes with gadolinium solution cores exhibited increasing magnetic susceptibility, and insertion loss (S21) also showed higher attenuation as gadolinium concentration increased. Image artifacts extending <4 mm from the choke were observed during magnetic resonance imaging, which agreed well with the predicted ∼3 mm artifact from the electrochemical machining simulation. An accompanying temperature increase of <1 °C was observed in the magnetic resonance imaging phantom trial. An effective paramagnetic choke for radio frequency suppression during magnetic resonance imaging was developed and its performance demonstrated.
Collapse
Affiliation(s)
- Kevin J Wu
- 1 School of Electrical and Computer Engineering, College of Engineering, University of Georgia, Athens, GA, USA
| | - T Stan Gregory
- 1 School of Electrical and Computer Engineering, College of Engineering, University of Georgia, Athens, GA, USA
| | - Brian L Boland
- 1 School of Electrical and Computer Engineering, College of Engineering, University of Georgia, Athens, GA, USA
| | - Wujun Zhao
- 2 Department of Chemistry, University of Georgia, Athens, GA, USA
| | - Rui Cheng
- 1 School of Electrical and Computer Engineering, College of Engineering, University of Georgia, Athens, GA, USA
| | - Leidong Mao
- 1 School of Electrical and Computer Engineering, College of Engineering, University of Georgia, Athens, GA, USA
| | - Zion Tsz Ho Tse
- 1 School of Electrical and Computer Engineering, College of Engineering, University of Georgia, Athens, GA, USA
| |
Collapse
|
21
|
Kakareka JW, Faranesh AZ, Pursley RH, Campbell-Washburn A, Herzka DA, Rogers T, Kanter J, Ratnayaka K, Lederman RJ, Pohida TJ. Physiological Recording in the MRI Environment (PRiME): MRI-Compatible Hemodynamic Recording System. IEEE JOURNAL OF TRANSLATIONAL ENGINEERING IN HEALTH AND MEDICINE-JTEHM 2018; 6:4100112. [PMID: 29552426 PMCID: PMC5849467 DOI: 10.1109/jtehm.2018.2807813] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Revised: 12/20/2017] [Accepted: 02/01/2018] [Indexed: 12/26/2022]
Abstract
Hemodynamic recording during interventional cardiovascular procedures is essential for procedural guidance, monitoring patient status, and collection of diagnostic information. Recent advances have made interventions guided by magnetic resonance imaging (MRI) possible and attractive in certain clinical scenarios. However, in the MRI environment, electromagnetic interference (EMI) can cause severe distortions and artifacts in acquired hemodynamic waveforms. The primary aim of this paper was to develop and validate a system to minimize EMI on electrocardiogram (ECG) and invasive blood pressure (IBP) signals. A system was developed which incorporated commercial MRI compatible ECG leads and pressure transducers, custom electronics, user interface, and adaptive signal processing. Measurements were made on pediatric patients (N = 6) during MRI-guided catheterization. Real-time interactive scanning, which is known to produce significant EMI due to fast gradient switching and varying imaging plane orientations, was selected for testing. The effectiveness of the adaptive algorithms was determined by measuring the reduction of noise peaks, amplitude of noise peaks, and false QRS triggers. During real-time gradient-intensive imaging sequences, peak noise amplitude was reduced by 80% and false QRS triggers were reduced to a median of 0. There was no detectable interference on the IBP channels. A hemodynamic recording system front-end was successfully developed and deployed, which enabled high-fidelity recording of ECG and IBP during MRI scanning. The schematics and assembly instructions are publicly available to facilitate implementation at other institutions. Researchers and clinicians are provided a critical tool in investigating and implementing MRI guided interventional cardiovascular procedures.
Collapse
Affiliation(s)
| | | | | | | | | | - Toby Rogers
- National Institutes of HealthBethesdaMD20892USA
| | - Josh Kanter
- Children's National Health SystemWashingtonDC20010USA
| | | | | | | |
Collapse
|
22
|
Berruezo A, Paetsch I. Inception: implanting the idea of magnetic resonance imaging-guided ventricular tachycardia substrate ablation. Europace 2017; 20:f143-f145. [DOI: 10.1093/europace/eux367] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Antonio Berruezo
- Arrhythmia Section, Cardiology Department, Institut Clínic Cardiovascular, Hospital Clínic, Universitat de Barcelona, Institut d’Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), C/Villarroel 170, Barcelona, Spain
| | - Ingo Paetsch
- Department of Electrophysiology, HELIOS Heart Center Leipzig, University of Leipzig, Struempellstr. 39, Leipzig, Germany
- Department of Cardiology, HELIOS Heart Center Leipzig, University of Leipzig, Struempellstr. 39, Leipzig, Germany
| |
Collapse
|
23
|
Abstract
Image-guided percutaneous, minimally invasive ablation techniques offer a wide variety of new modalities to treat tumors in some of the most medically complicated patients coming to our hospitals. The use of computed tomography, PET, ultrasound imaging, and MRI to guide radiofrequency ablation, microwave ablation, and cryoablation techniques now makes it possible to treat patients on a short stay or outpatient basis with very good immediate outcomes. This rapid expansion of new tumor ablation techniques often presents challenges for the non-operating room anesthesia team. Collaboration and communication between the radiologist and anesthesiologist are key to safety and excellent patient outcomes.
Collapse
|
24
|
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]
|
25
|
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.
Collapse
Affiliation(s)
- Julien Oster
- IADI, U947, INSERM, Université de Lorraine, CHRU Nancy, Vandoeuvre-les-Nancy, France
| | | |
Collapse
|
26
|
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.
Collapse
|
27
|
Schmidt EJ, Watkins RD, Zviman MM, Guttman MA, Wang W, Halperin HA. A Magnetic Resonance Imaging-Conditional External Cardiac Defibrillator for Resuscitation Within the Magnetic Resonance Imaging Scanner Bore. Circ Cardiovasc Imaging 2017; 9:CIRCIMAGING.116.005091. [PMID: 27729363 DOI: 10.1161/circimaging.116.005091] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Accepted: 08/22/2016] [Indexed: 12/13/2022]
Abstract
BACKGROUND Subjects undergoing cardiac arrest within a magnetic resonance imaging (MRI) scanner are currently removed from the bore and then from the MRI suite, before the delivery of cardiopulmonary resuscitation and defibrillation, potentially increasing the risk of mortality. This precludes many higher-risk (acute ischemic and acute stroke) patients from undergoing MRI and MRI-guided intervention. An MRI-conditional cardiac defibrillator should enable scanning with defibrillation pads attached and the generator ON, enabling application of defibrillation within the seconds of MRI after a cardiac event. An MRI-conditional external defibrillator may improve patient acceptance for MRI procedures. METHODS AND RESULTS A commercial external defibrillator was rendered 1.5 Tesla MRI-conditional by the addition of novel radiofrequency filters between the generator and commercial disposable surface pads. The radiofrequency filters reduced emission into the MRI scanner and prevented cable/surface pad heating during imaging, while preserving all the defibrillator monitoring and delivery functions. Human volunteers were imaged using high specific absorption rate sequences to validate MRI image quality and lack of heating. Swine were electrically fibrillated (n=4) and thereafter defibrillated both outside and inside the MRI bore. MRI image quality was reduced by 0.8 or 1.6 dB, with the generator in monitoring mode and operating on battery or AC power, respectively. Commercial surface pads did not create artifacts deeper than 6 mm below the skin surface. Radiofrequency heating was within US Food and Drug Administration guidelines. Defibrillation was completely successful inside and outside the MRI bore. CONCLUSIONS A prototype MRI-conditional defibrillation system successfully defibrillated in the MRI without degrading the image quality or increasing the time needed for defibrillation. It can increase patient acceptance for MRI procedures.
Collapse
Affiliation(s)
- Ehud J Schmidt
- From the Department of Radiology, Brigham and Women's Hospital, Boston, MA (E.J.S., W.W.); Department of Radiology, Stanford University, CA (R.D.W.); and Department of Cardiology, Johns Hopkins University, Baltimore, MD (M.M.Z., M.A.G., H.A.H.).
| | - Ronald D Watkins
- From the Department of Radiology, Brigham and Women's Hospital, Boston, MA (E.J.S., W.W.); Department of Radiology, Stanford University, CA (R.D.W.); and Department of Cardiology, Johns Hopkins University, Baltimore, MD (M.M.Z., M.A.G., H.A.H.)
| | - Menekhem M Zviman
- From the Department of Radiology, Brigham and Women's Hospital, Boston, MA (E.J.S., W.W.); Department of Radiology, Stanford University, CA (R.D.W.); and Department of Cardiology, Johns Hopkins University, Baltimore, MD (M.M.Z., M.A.G., H.A.H.)
| | - Michael A Guttman
- From the Department of Radiology, Brigham and Women's Hospital, Boston, MA (E.J.S., W.W.); Department of Radiology, Stanford University, CA (R.D.W.); and Department of Cardiology, Johns Hopkins University, Baltimore, MD (M.M.Z., M.A.G., H.A.H.)
| | - Wei Wang
- From the Department of Radiology, Brigham and Women's Hospital, Boston, MA (E.J.S., W.W.); Department of Radiology, Stanford University, CA (R.D.W.); and Department of Cardiology, Johns Hopkins University, Baltimore, MD (M.M.Z., M.A.G., H.A.H.)
| | - Henry A Halperin
- From the Department of Radiology, Brigham and Women's Hospital, Boston, MA (E.J.S., W.W.); Department of Radiology, Stanford University, CA (R.D.W.); and Department of Cardiology, Johns Hopkins University, Baltimore, MD (M.M.Z., M.A.G., H.A.H.)
| |
Collapse
|
28
|
Rosero EB, Joshi GP. Ambulatory Anesthesia in Remote Locations. CURRENT ANESTHESIOLOGY REPORTS 2016. [DOI: 10.1007/s40140-016-0181-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
|
29
|
Magnetic resonance imaging guided transatrial electrophysiological studies in swine using active catheter tracking - experience with 14 cases. Eur Radiol 2016; 27:1954-1962. [PMID: 27553931 DOI: 10.1007/s00330-016-4560-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Revised: 07/14/2016] [Accepted: 08/11/2016] [Indexed: 10/21/2022]
Abstract
OBJECTIVES To evaluate the feasibility of performing comprehensive Cardiac Magnetic resonance (CMR) guided electrophysiological (EP) interventions in a porcine model encompassing left atrial access. METHODS After introduction of two femoral sheaths 14 swine (41 ± 3.6 kg) were transferred to a 1.5 T MR scanner. A three-dimensional whole-heart sequence was acquired followed by segmentation and the visualization of all heart chambers using an image-guidance platform. Two MR conditional catheters were inserted. The interventional protocol consisted of intubation of the coronary sinus, activation mapping, transseptal left atrial access (n = 4), generation of ablation lesions and eventually ablation of the atrioventricular (AV) node. For visualization of the catheter tip active tracking was used. Catheter positions were confirmed by passive real-time imaging. RESULTS Total procedure time was 169 ± 51 minutes. The protocol could be completed in 12 swine. Two swine died from AV-ablation induced ventricular fibrillation. Catheters could be visualized and navigated under active tracking almost exclusively. The position of the catheter tips as visualized by active tracking could reliably be confirmed with passive catheter imaging. CONCLUSIONS Comprehensive CMR-guided EP interventions including left atrial access are feasible in swine using active catheter tracking. KEY POINTS • Comprehensive CMR-guided electrophysiological interventions including LA access were conducted in swine. • Active catheter-tracking allows efficient catheter navigation also in a transseptal approach. • More MR-conditional tools are needed to facilitate left atrial interventions in humans.
Collapse
|
30
|
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.
Collapse
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
| |
Collapse
|
31
|
Wu KJ, Stan Gregory T, Reader C, Leitmann B, Huffines A, Donovan S, Mosteller L, Murrow JR, Tse ZTH. Smartphone-Enabled Flow-Monitoring Device for Peripheral Artery Disease1. J Med Device 2016. [DOI: 10.1115/1.4033152] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Affiliation(s)
- Kevin J. Wu
- College of Engineering, The University of Georgia, Athens, GA 30602
| | - T. Stan Gregory
- College of Engineering, The University of Georgia, Athens, GA 30602
| | - Charles Reader
- College of Engineering, The University of Georgia, Athens, GA 30602
| | - Bobby Leitmann
- College of Engineering, The University of Georgia, Athens, GA 30602
| | | | - Sheila Donovan
- College of Engineering, The University of Georgia, Athens, GA 30602
| | - Luke Mosteller
- College of Engineering, The University of Georgia, Athens, GA 30602
| | - Jonathan R. Murrow
- Athens Regional Medical Center, The University of Georgia & Georgia Regents University Medical Partnership, Athens, GA 30602
| | - Zion Tsz Ho Tse
- College of Engineering, The University of Georgia, Athens, GA 30602
| |
Collapse
|
32
|
Sakaki M, Yoo HJ, Nga L, Lee TH, Thayer JF, Mather M. Heart rate variability is associated with amygdala functional connectivity with MPFC across younger and older adults. Neuroimage 2016; 139:44-52. [PMID: 27261160 DOI: 10.1016/j.neuroimage.2016.05.076] [Citation(s) in RCA: 142] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Revised: 05/16/2016] [Accepted: 05/28/2016] [Indexed: 12/30/2022] Open
Abstract
The ability to regulate emotion is crucial to promote well-being. Evidence suggests that the medial prefrontal cortex (mPFC) and adjacent anterior cingulate (ACC) modulate amygdala activity during emotion regulation. Yet less is known about whether the amygdala-mPFC circuit is linked with regulation of the autonomic nervous system and whether the relationship differs across the adult lifespan. The current study tested the hypothesis that heart rate variability (HRV) reflects the strength of mPFC-amygdala interaction across younger and older adults. We recorded participants' heart rates at baseline and examined whether baseline HRV was associated with amygdala-mPFC functional connectivity during rest. We found that higher HRV was associated with stronger functional connectivity between the amygdala and the mPFC during rest across younger and older adults. In addition to this age-invariant pattern, there was an age-related change, such that greater HRV was linked with stronger functional connectivity between amygdala and ventrolateral PFC (vlPFC) in younger than in older adults. These results are in line with past evidence that vlPFC is involved in emotion regulation especially in younger adults. Taken together, our results support the neurovisceral integration model and suggest that higher heart rate variability is associated with neural mechanisms that support successful emotional regulation across the adult lifespan.
Collapse
Affiliation(s)
- Michiko Sakaki
- University of Reading, UK; Kochi University of Technology, Japan.
| | - Hyun Joo Yoo
- University of Southern California, United States
| | - Lin Nga
- University of Southern California, United States
| | - Tae-Ho Lee
- University of Illinois, Urbana-Champaign, United States
| | | | - Mara Mather
- University of Southern California, United States
| |
Collapse
|
33
|
Gregory TS, Oshinski J, Schmidt EJ, Kwong RY, Stevenson WG, Ho Tse ZT. Continuous Rapid Quantification of Stroke Volume Using Magnetohydrodynamic Voltages in 3T Magnetic Resonance Imaging. Circ Cardiovasc Imaging 2016; 8:CIRCIMAGING.115.003282. [PMID: 26628581 DOI: 10.1161/circimaging.115.003282] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND To develop a technique to noninvasively estimate stroke volume in real time during magnetic resonance imaging (MRI)-guided procedures, based on induced magnetohydrodynamic voltages (VMHD) that occur in ECG recordings during MRI exams, leaving the MRI scanner free to perform other imaging tasks. Because of the relationship between blood flow (BF) and VMHD, we hypothesized that a method to obtain stroke volume could be derived from extracted VMHD vectors in the vectorcardiogram (VCG) frame of reference (VMHDVCG). METHODS AND RESULTS To estimate a subject-specific BF-VMHD model, VMHDVCG was acquired during a 20-s breath-hold and calibrated versus aortic BF measured using phase-contrast magnetic resonance in 10 subjects (n=10) and 1 subject diagnosed with premature ventricular contractions. Beat-to-beat validation of VMHDVCG-derived BF was performed using real-time phase-contrast imaging in 7 healthy subjects (n=7) during 15-minute cardiac exercise stress tests and 30 minutes after stress relaxation in 3T MRIs. Subject-specific equations were derived to correlate VMHDVCG with BF at rest and validated using real-time phase-contrast. An average error of 7.22% and 3.69% in stroke volume estimation, respectively, was found during peak stress and after complete relaxation. Measured beat-to-beat BF time history derived from real-time phase-contrast and VMHD was highly correlated using a Spearman rank correlation coefficient during stress tests (0.89) and after stress relaxation (0.86). CONCLUSIONS Accurate beat-to-beat stroke volume and BF were estimated using VMHDVCG extracted from intra-MRI 12-lead ECGs, providing a means to enhance patient monitoring during MR imaging and MR-guided interventions.
Collapse
Affiliation(s)
- T Stan Gregory
- From the College of Engineering, University of Georgia, Athens (T.S.G., Z.T.H.T.); Departments of Radiology and Imaging Sciences, Emory University Hospital, Atlanta, GA (J.O.); Departments of Radiology (E.J.S.) and Cardiology (R.Y.K., W.G.S.), Brigham and Women's Hospital, Boston, MA
| | - John Oshinski
- From the College of Engineering, University of Georgia, Athens (T.S.G., Z.T.H.T.); Departments of Radiology and Imaging Sciences, Emory University Hospital, Atlanta, GA (J.O.); Departments of Radiology (E.J.S.) and Cardiology (R.Y.K., W.G.S.), Brigham and Women's Hospital, Boston, MA
| | - Ehud J Schmidt
- From the College of Engineering, University of Georgia, Athens (T.S.G., Z.T.H.T.); Departments of Radiology and Imaging Sciences, Emory University Hospital, Atlanta, GA (J.O.); Departments of Radiology (E.J.S.) and Cardiology (R.Y.K., W.G.S.), Brigham and Women's Hospital, Boston, MA
| | - Raymond Y Kwong
- From the College of Engineering, University of Georgia, Athens (T.S.G., Z.T.H.T.); Departments of Radiology and Imaging Sciences, Emory University Hospital, Atlanta, GA (J.O.); Departments of Radiology (E.J.S.) and Cardiology (R.Y.K., W.G.S.), Brigham and Women's Hospital, Boston, MA
| | - William G Stevenson
- From the College of Engineering, University of Georgia, Athens (T.S.G., Z.T.H.T.); Departments of Radiology and Imaging Sciences, Emory University Hospital, Atlanta, GA (J.O.); Departments of Radiology (E.J.S.) and Cardiology (R.Y.K., W.G.S.), Brigham and Women's Hospital, Boston, MA
| | - Zion Tsz Ho Tse
- From the College of Engineering, University of Georgia, Athens (T.S.G., Z.T.H.T.); Departments of Radiology and Imaging Sciences, Emory University Hospital, Atlanta, GA (J.O.); Departments of Radiology (E.J.S.) and Cardiology (R.Y.K., W.G.S.), Brigham and Women's Hospital, Boston, MA.
| |
Collapse
|
34
|
Schmidt EJ. Magnetic Resonance Imaging-Guided Cardiac Interventions. Magn Reson Imaging Clin N Am 2015; 23:563-77. [PMID: 26499275 DOI: 10.1016/j.mric.2015.05.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Performing intraoperative cardiovascular procedures inside an MR imaging scanner can potentially provide substantial advantage in clinical outcomes by reducing the risk and increasing the success rate relative to the way such procedures are performed today, in which the primary surgical guidance is provided by X-ray fluoroscopy, by electromagnetically tracked intraoperative devices, and by ultrasound. Both noninvasive and invasive cardiologists are becoming increasingly familiar with the capabilities of MR imaging for providing anatomic and physiologic information that is unequaled by other modalities. As a result, researchers began performing animal (preclinical) interventions in the cardiovascular system in the early 1990s.
Collapse
Affiliation(s)
- Ehud J Schmidt
- Radiology Department, Brigham and Women's Hospital, 221 Longwood Avenue, Room BRB 34C, Boston, MA 02115, USA.
| |
Collapse
|
35
|
Zhang SH, Tse ZTH, Dumoulin CL, Kwong RY, Stevenson WG, Watkins R, Ward J, Wang W, Schmidt EJ. Gradient-induced voltages on 12-lead ECGs during high duty-cycle MRI sequences and a method for their removal considering linear and concomitant gradient terms. Magn Reson Med 2015; 75:2204-16. [PMID: 26101951 DOI: 10.1002/mrm.25810] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Revised: 05/18/2015] [Accepted: 05/23/2015] [Indexed: 11/08/2022]
Abstract
PURPOSE To restore 12-lead electrocardiographic (ECG) signal fidelity inside MRI by removing magnetic field gradient-induced voltages during high gradient duty cycle sequences. THEORY AND METHODS A theoretical equation was derived to provide first- and second-order electrical fields induced at individual ECG electrodes as a function of gradient fields. Experiments were performed at 3T on healthy volunteers using a customized acquisition system that captured the full amplitude and frequency response of ECGs, or a commercial recording system. The 19 equation coefficients were derived via linear regression of data from accelerated sequences and were used to compute induced voltages in real-time during full resolution sequences to remove ECG artifacts. Restored traces were evaluated relative to ones acquired without imaging. RESULTS Measured induced voltages were 0.7 V peak-to-peak during balanced steady state free precession (bSSFP) with the heart at the isocenter. Applying the equation during gradient echo sequencing, three-dimensional fast spin echo, and multislice bSSFP imaging restored nonsaturated traces and second-order concomitant terms showed larger contributions in electrodes further from the magnet isocenter. Equation coefficients are evaluated with high repeatability (ρ = 0.996) and are dependent on subject, sequence, and slice orientation. CONCLUSION Close agreement between theoretical and measured gradient-induced voltages allowed for real-time removal. Prospective estimation of sequence periods in which large induced voltages occur may allow hardware removal of these signals.
Collapse
Affiliation(s)
- Shelley HuaLei Zhang
- Department of Radiology, Brigham and Women's Hospital, Boston, Massachusetts, USA
| | - Zion Tsz Ho Tse
- Department of Engineering, University of Georgia, Athens, Georgia, USA
| | - Charles L Dumoulin
- Department of Radiology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA
| | - Raymond Y Kwong
- Department of Cardiology, Brigham and Women's Hospital, Boston, Massachusetts, USA
| | - William G Stevenson
- Department of Cardiology, Brigham and Women's Hospital, Boston, Massachusetts, USA
| | - Ronald Watkins
- Department of Radiology, Stanford University, Stanford, California, USA
| | - Jay Ward
- E-TROLZ Inc, North Andover, Massachusetts, USA
| | - Wei Wang
- Department of Radiology, Brigham and Women's Hospital, Boston, Massachusetts, USA
| | - Ehud J Schmidt
- Department of Radiology, Brigham and Women's Hospital, Boston, Massachusetts, USA
| |
Collapse
|
36
|
Bhagirath P, van der Graaf M, Karim R, Rhode K, Piorkowski C, Razavi R, Schwitter J, Götte M. Interventional cardiac magnetic resonance imaging in electrophysiology: advances toward clinical translation. Circ Arrhythm Electrophysiol 2015; 8:203-11. [PMID: 25691554 DOI: 10.1161/circep.114.002371] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Pranav Bhagirath
- From the Department of Cardiology, Haga Teaching Hospital, The Hague, The Netherlands (P.B., M.v.d.G., M.G.); Division of Imaging Sciences and Biomedical Engineering, King's College London, London, United Kingdom (R.K., K.R., R.R.); Department of Electrophysiology, University of Dresden-Heart Center, Dresden, Germany (C.P.); and Department of Cardiology, University Hospital Lausanne, Centre hospitalier universitaire vaudois (CHUV), Lausanne, Switzerland (J.S.)
| | - Maurits van der Graaf
- From the Department of Cardiology, Haga Teaching Hospital, The Hague, The Netherlands (P.B., M.v.d.G., M.G.); Division of Imaging Sciences and Biomedical Engineering, King's College London, London, United Kingdom (R.K., K.R., R.R.); Department of Electrophysiology, University of Dresden-Heart Center, Dresden, Germany (C.P.); and Department of Cardiology, University Hospital Lausanne, Centre hospitalier universitaire vaudois (CHUV), Lausanne, Switzerland (J.S.)
| | - Rashed Karim
- From the Department of Cardiology, Haga Teaching Hospital, The Hague, The Netherlands (P.B., M.v.d.G., M.G.); Division of Imaging Sciences and Biomedical Engineering, King's College London, London, United Kingdom (R.K., K.R., R.R.); Department of Electrophysiology, University of Dresden-Heart Center, Dresden, Germany (C.P.); and Department of Cardiology, University Hospital Lausanne, Centre hospitalier universitaire vaudois (CHUV), Lausanne, Switzerland (J.S.)
| | - Kawal Rhode
- From the Department of Cardiology, Haga Teaching Hospital, The Hague, The Netherlands (P.B., M.v.d.G., M.G.); Division of Imaging Sciences and Biomedical Engineering, King's College London, London, United Kingdom (R.K., K.R., R.R.); Department of Electrophysiology, University of Dresden-Heart Center, Dresden, Germany (C.P.); and Department of Cardiology, University Hospital Lausanne, Centre hospitalier universitaire vaudois (CHUV), Lausanne, Switzerland (J.S.)
| | - Christopher Piorkowski
- From the Department of Cardiology, Haga Teaching Hospital, The Hague, The Netherlands (P.B., M.v.d.G., M.G.); Division of Imaging Sciences and Biomedical Engineering, King's College London, London, United Kingdom (R.K., K.R., R.R.); Department of Electrophysiology, University of Dresden-Heart Center, Dresden, Germany (C.P.); and Department of Cardiology, University Hospital Lausanne, Centre hospitalier universitaire vaudois (CHUV), Lausanne, Switzerland (J.S.)
| | - Reza Razavi
- From the Department of Cardiology, Haga Teaching Hospital, The Hague, The Netherlands (P.B., M.v.d.G., M.G.); Division of Imaging Sciences and Biomedical Engineering, King's College London, London, United Kingdom (R.K., K.R., R.R.); Department of Electrophysiology, University of Dresden-Heart Center, Dresden, Germany (C.P.); and Department of Cardiology, University Hospital Lausanne, Centre hospitalier universitaire vaudois (CHUV), Lausanne, Switzerland (J.S.)
| | - Juerg Schwitter
- From the Department of Cardiology, Haga Teaching Hospital, The Hague, The Netherlands (P.B., M.v.d.G., M.G.); Division of Imaging Sciences and Biomedical Engineering, King's College London, London, United Kingdom (R.K., K.R., R.R.); Department of Electrophysiology, University of Dresden-Heart Center, Dresden, Germany (C.P.); and Department of Cardiology, University Hospital Lausanne, Centre hospitalier universitaire vaudois (CHUV), Lausanne, Switzerland (J.S.)
| | - Marco Götte
- From the Department of Cardiology, Haga Teaching Hospital, The Hague, The Netherlands (P.B., M.v.d.G., M.G.); Division of Imaging Sciences and Biomedical Engineering, King's College London, London, United Kingdom (R.K., K.R., R.R.); Department of Electrophysiology, University of Dresden-Heart Center, Dresden, Germany (C.P.); and Department of Cardiology, University Hospital Lausanne, Centre hospitalier universitaire vaudois (CHUV), Lausanne, Switzerland (J.S.).
| |
Collapse
|
37
|
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.
Collapse
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
| |
Collapse
|
38
|
Oster J, Llinares R, Payne S, Tse ZTH, Schmidt EJ, Clifford GD. Comparison of three artificial models of the magnetohydrodynamic effect on the electrocardiogram. Comput Methods Biomech Biomed Engin 2014; 18:1400-17. [PMID: 24761753 DOI: 10.1080/10255842.2014.909090] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
The electrocardiogram (ECG) is often acquired during magnetic resonance imaging (MRI), but its analysis is restricted by the presence of a strong artefact, called magnetohydrodynamic (MHD) effect. MHD effect is induced by the flow of electrically charged particles in the blood perpendicular to the static magnetic field, which creates a potential of the order of magnitude of the ECG and temporally coincident with the repolarisation period. In this study, a new MHD model is proposed by using MRI-based 4D blood flow measurements made across the aortic arch. The model is extended to several cardiac cycles to allow the simulation of a realistic ECG acquisition during MRI examination and the quality assessment of MHD suppression techniques. A comparison of two existing models, based, respectively, on an analytical solution and on a numerical method-based solution of the fluids dynamics problem, is made with the proposed model and with an estimate of the MHD voltage observed during a real MRI scan. Results indicate a moderate agreement between the proposed model and the estimated MHD model for most leads, with an average correlation factor of 0.47. However, the results demonstrate that the proposed model provides a closer approximation to the observed MHD effects and a better depiction of the complexity of the MHD effect compared with the previously published models, with an improved correlation (+5%), coefficient of determination (+22%) and fraction of energy (+1%) compared with the best previous model. The source code will be made freely available under an open source licence to facilitate collaboration and allow more rapid development of more accurate models of the MHD effect.
Collapse
Affiliation(s)
- Julien Oster
- a Department of Engineering Science , Institute of Biomedical Engineering, University of Oxford , Oxford , UK
| | | | | | | | | | | |
Collapse
|
39
|
Gregory TS, Schmidt EJ, Zhang SH, Ho Tse ZT. 3DQRS: a method to obtain reliable QRS complex detection within high field MRI using 12-lead electrocardiogram traces. Magn Reson Med 2014; 71:1374-80. [PMID: 24453116 DOI: 10.1002/mrm.25078] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2013] [Revised: 11/01/2013] [Accepted: 11/02/2013] [Indexed: 11/09/2022]
Abstract
PURPOSE To develop a technique that accurately detects the QRS complex in 1.5 Tesla (T), 3T, and 7T MRI scanners. METHODS During early systole, blood is rapidly ejected into the aortic arch, traveling perpendicular to the MRI's main field, which produces a strong voltage (V(MHD)) that eclipses the QRS complex. Greater complexity arises in arrhythmia patients, since V(MHD) varies between sinus-rhythm and arrhythmic beats. The 3DQRS method uses a kernel consisting of 6 electrocardiogram (ECG) precordial leads (V1-V6), compiled from a 12-lead ECG performed outside the magnet. The kernel is cross-correlated with signals acquired inside the MRI to identify the QRS complex in real time. The 3DQRS method was evaluated against a vectorcardiogram (VCG)-based approach in two premature ventricular contraction (PVC) and two atrial fibrillation (AF) patients, a healthy exercising athlete, and eight healthy volunteers, within 1.5T and 3T MRIs, using a prototype MRI-conditional 12-lead ECG system. Two volunteers were recorded at 7T using a Holter recorder. RESULTS For QRS complex detection, 3DQRS subject-averaged sensitivity levels, relative to VCG were: 1.5T (100% versus 96.7%), 3T (98.9% versus 92.2%), and 7T (96.2% versus 77.7%). CONCLUSION The 3DQRS method was shown to be more effective in cardiac gating than a conventional VCG-based method.
Collapse
Affiliation(s)
- T Stan Gregory
- College of Engineering, The University of Georgia, Athens, Georgia, USA
| | | | | | | |
Collapse
|
40
|
Krug JW, Rose G, Clifford GD, Oster J. ECG-based gating in ultra high field cardiovascular magnetic resonance using an independent component analysis approach. J Cardiovasc Magn Reson 2013; 15:104. [PMID: 24252594 PMCID: PMC4174900 DOI: 10.1186/1532-429x-15-104] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2013] [Accepted: 10/16/2013] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND In Cardiovascular Magnetic Resonance (CMR), the synchronization of image acquisition with heart motion is performed in clinical practice by processing the electrocardiogram (ECG). The ECG-based synchronization is well established for MR scanners with magnetic fields up to 3 T. However, this technique is prone to errors in ultra high field environments, e.g. in 7 T MR scanners as used in research applications. The high magnetic fields cause severe magnetohydrodynamic (MHD) effects which disturb the ECG signal. Image synchronization is thus less reliable and yields artefacts in CMR images. METHODS A strategy based on Independent Component Analysis (ICA) was pursued in this work to enhance the ECG contribution and attenuate the MHD effect. ICA was applied to 12-lead ECG signals recorded inside a 7 T MR scanner. An automatic source identification procedure was proposed to identify an independent component (IC) dominated by the ECG signal. The identified IC was then used for detecting the R-peaks. The presented ICA-based method was compared to other R-peak detection methods using 1) the raw ECG signal, 2) the raw vectorcardiogram (VCG), 3) the state-of-the-art gating technique based on the VCG, 4) an updated version of the VCG-based approach and 5) the ICA of the VCG. RESULTS ECG signals from eight volunteers were recorded inside the MR scanner. Recordings with an overall length of 87 min accounting for 5457 QRS complexes were available for the analysis. The records were divided into a training and a test dataset. In terms of R-peak detection within the test dataset, the proposed ICA-based algorithm achieved a detection performance with an average sensitivity (Se) of 99.2%, a positive predictive value (+P) of 99.1%, with an average trigger delay and jitter of 5.8 ms and 5.0 ms, respectively. Long term stability of the demixing matrix was shown based on two measurements of the same subject, each being separated by one year, whereas an averaged detection performance of Se = 99.4% and +P = 99.7% was achieved.Compared to the state-of-the-art VCG-based gating technique at 7 T, the proposed method increased the sensitivity and positive predictive value within the test dataset by 27.1% and 42.7%, respectively. CONCLUSIONS The presented ICA-based method allows the estimation and identification of an IC dominated by the ECG signal. R-peak detection based on this IC outperforms the state-of-the-art VCG-based technique in a 7 T MR scanner environment.
Collapse
Affiliation(s)
- Johannes W Krug
- Department of Electrical Engineering and Information Technology, Otto-von-Guericke University, Magdeburg, Germany
| | - Georg Rose
- Department of Electrical Engineering and Information Technology, Otto-von-Guericke University, Magdeburg, Germany
| | - Gari D Clifford
- Department of Engineering Science, University of Oxford, Oxford, UK
| | - Julien Oster
- Department of Engineering Science, University of Oxford, Oxford, UK
| |
Collapse
|