Feasibility of Cardiac Gating Free of Interference With Electro-Magnetic Fields at 1.5 Tesla, 3.0 Tesla and 7.0 Tesla Using an MR-Stethoscope

Frauenrath, Tobias; Hezel, Fabian; Heinrichs, U.; Kozerke, Sebastian; Utting, Jane F.; Kob, Malte; Butenweg, Christoph; Boesiger, Peter; Niendorf, Thoralf

doi:10.1097/rli.0b013e3181b4c15e

Cited by 69 publications

(49 citation statements)

References 51 publications

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“…Other studies in which MR-stethoscopes were modified to meet the demands of cardiac/triggered MRI have been conducted (12). The acoustic cardiac triggering (ACT) approach used in these studies exploited the acoustic signal generated by the heart.…”

Section: Discussionmentioning

confidence: 99%

“…The study demonstrated that the true triggered images were superior to the self-gated images. There are some other approaches, too; recent studies applied an acoustic cardiac triggering mechanism using an MR-stethoscope that picks up the acoustic signals generated by the heart (12,13). This device was fully compatible with the ECG trigger unit of the MRI devices.…”

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confidence: 99%

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Cardiac MRI of the fetal heart using a novel triggering method: Initial results in an animal model

Yamamura

Kopp

Frisch

et al. 2012

Magnetic Resonance Imaging

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Purpose: To investigate MRI of the fetal heart by way of a novel triggering method with the use of an MR-compatible cardiotocography (CTG) in an animal model. Materials and Methods:Fetal cardiac MRI was performed on four pregnant ewes on a 1.5 Tesla (T) MR system. A CTG was rendered MR compatible and its signal was used for the triggering of the fetal heart to perform cardiac cine MRI of the fetal heart with maternal freebreathing with cine steady-state free precession. The left ventricular volume and function were measured from the short-axis (view). The image quality of anatomical structures was assessed.Results: All cardiac valves and the foramen ovale could be visualized. Myocardial contraction was depicted in cine sequences. The average blood volume at the end systole was 1.7 mL (SD 6 0.12). The average volume at the end diastole was 4.6 mL (6 0.4); thus the average stroke volumes of the left ventricle were 2.87 mL (6 0.31) with ejection fractions of 60.53% (6 4.17). Conclusion:The newly developed MR compatible CTG could be used as a tool for cardiac triggering method of the fetal heart. This novel device might help fetal cardiac MRI technology in the future. THE RAPID DEVELOPMENT of cardiac MR imaging in the past few years has enabled many different investigations, for example investigations into coronary arteries and myocardial infarctions. In practice, twodimensional (2D) CINE steady-state free precession (SSFP) imaging is the most reliable and frequently used technique for left ventricular (LV) function assessment. To assess the LV function correctly, speed as well as synchronization of data acquisition with the cardiac cycle are required, so that artifacts due to cardiac motion and flow constraints that dictate the viable window for data acquisition are avoided. To avoid the artifacts caused by cardiac motion, it is customary that either finger pulse oximetry or electrocardiography (ECG) triggering/gating techniques are used so that data acquisition can be synchronized with the cardiac cycle.Although the use of MR imaging during pregnancy is limited to the second and third trimester, its diagnostic value has been increasing in recent years. In the field of fetal MR imaging, the evaluation of the fetal heart is one of the greatest challenges. Nowadays, the gold standard in fetal cardiac imaging is the use of ultrasound (US), because it can be obtained during the entire pregnancy; it is easy to use and thus more practicable. Both the measurement of the cardiac volume and the evaluation of volumetric changes with US are possible, and the technology has been improving. Because cardiac chambers do not lend themselves to geometric assumptions, it has always been difficult to calculate their dimensions, even though studies have shown that 3D US has a better reproducibility than 2D (1-4). To be able to do so, it is necessary to trace the volume of the cardiac chambers manually, due to the appearance of various US specific artifacts, such as speckles and acoustic shadowing, which appear when traced automaticall...

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

Cardiac MRI of the fetal heart using a novel triggering method: Initial results in an animal model

Yamamura

Kopp

Frisch

et al. 2012

Magnetic Resonance Imaging

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“…This susceptibility to electromagnetic field (EMF) interference manifests itself in ECG waveform distortions already present in ECG traces acquired at 1.5 T and lower fields (2,5). As high and ultrahigh field MR becomes more widespread, the susceptibility of ECG recordings to MHD effects is further pronounced (6)(7)(8)(9). Artifacts in the ECG trace and severe T-wave elevation might be misinterpreted as R-waves, resulting in misdetection of cardiac activity or erroneous cardiac gating.…”

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confidence: 99%

“…Contrary to the notion (5,8,18,19) that considers MHD effects as adverse concomitants of traditional ECG acquired in a magnetic field environment, this feasibility study explores the merits of MHD effects for cardiac-gated MRI. We propose that the MHD effect being inherently sensitive to magnetic flux density, flow orientation with respect to the magnetic field lines, and velocity of an electrical charge carrier such as blood can be put to use as an alternative approach for registration of cardiac activity and for cardiac gating/triggering.…”

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confidence: 99%

Detailing the use of magnetohydrodynamic effects for synchronization of MRI with the cardiac cycle: A feasibility study

Frauenrath

Fuchs

Dieringer

et al. 2012

Magnetic Resonance Imaging

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Purpose: To investigate the feasibility of using magnetohydrodynamic (MHD) effects for synchronization of magnetic resonance imaging (MRI) with the cardiac cycle. Materials and Methods:The MHD effect was scrutinized using a pulsatile flow phantom at B 0 ¼ 7.0 T. MHD effects were examined in vivo in healthy volunteers (n ¼ 10) for B 0 ranging from 0.05-7.0 T. Noncontrast-enhanced MR angiography (MRA) of the carotids was performed using a gated steadystate free-precession (SSFP) imaging technique in conjunction with electrocardiogram (ECG) and MHD synchronization. Results:The MHD potential correlates with flow velocities derived from phase contrast MRI. MHD voltages depend on the orientation between B 0 and the flow of a conductive fluid. An increase in the interelectrode spacing along the flow increases the MHD potential. In vivo measurement of the MHD effect provides peak voltages of 1.5 mV for surface areas close to the common carotid artery at B 0 ¼ 7.0 T. Synchronization of MRI with the cardiac cycle using MHD triggering is feasible. MHD triggered MRA of the carotids at 3.0 T showed an overall image quality and richness of anatomic detail, which is comparable to ECG-triggered MRAs. Conclusion:This feasibility study demonstrates the use of MHD effects for synchronization of MR acquisitions with the cardiac cycle.

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“…Consequently, image quality is impaired due to the mis-detected onset of a cardiac cycle. The propensity to MHD effects is pronounced at ultrahigh magnetic field strengths [42,68,69]. An MR-stethoscope has been proposed as an alternative to ECG gating and triggering putting acoustic signals to use which have been reported to be immune to interferences with electromagnetic fields.…”

Section: Ancillary Devices For Cardiac Synchronizationmentioning

confidence: 99%

Myocardial T2* Mapping with Ultrahigh Field Magnetic Resonance: Physics and Frontier Applications

Huelnhagen

Paul

et al. 2017

Front. Phys.

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Cardiovascular magnetic resonance imaging (CMR) has become an indispensable clinical tool for the assessment of morphology, function and structure of the heart muscle. By exploiting quantification of the effective transverse relaxation time (T 2 * ) CMR also affords myocardial tissue characterization and probing of cardiac physiology, both being in the focus of ongoing research. These developments are fueled by the move to ultrahigh magnetic field strengths, which permits enhanced sensitivity and spatial resolution that help to overcome limitations of current clinical MR systems with the goal to contribute to a better understanding of myocardial (patho)physiology in vivo. In this context, the aim of this report is to introduce myocardial T 2 * mapping at ultrahigh magnetic fields as a promising technique to non-invasively assess myocardial (patho)physiology. For this purpose the basic principles of T 2 * assessment, the biophysical mechanisms determining T 2 * and (pre)clinical applications of myocardial T 2 * mapping are presented.Technological challenges and solutions for T 2 * sensitized CMR at ultrahigh magnetic field strengths are discussed followed by a review of acquisition techniques and post-processing approaches. Preliminary results derived from myocardial T 2 * mapping in healthy subjects and cardiac patients at 7.0 T are presented. A concluding section discusses remaining questions and challenges and provides an outlook on future developments and potential clinical applications.

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Feasibility of Cardiac Gating Free of Interference With Electro-Magnetic Fields at 1.5 Tesla, 3.0 Tesla and 7.0 Tesla Using an MR-Stethoscope

Cited by 69 publications

References 51 publications

Cardiac MRI of the fetal heart using a novel triggering method: Initial results in an animal model

Cardiac MRI of the fetal heart using a novel triggering method: Initial results in an animal model

Detailing the use of magnetohydrodynamic effects for synchronization of MRI with the cardiac cycle: A feasibility study

Myocardial T2* Mapping with Ultrahigh Field Magnetic Resonance: Physics and Frontier Applications

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