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Article

7-Tesla Functional Cardiovascular MR Using Vectorcardiographic Triggering—Overcoming the Magnetohydrodynamic Effect

1
The Centre for Advanced Imaging, The University of Queensland, Brisbane, QLD 4000, Australia
2
MR Research Collaborations, Siemens Healthineers Pty Ltd., Bayswater, VIC 3153, Australia
3
Department of Medical Science, University of Oxford, Oxford 01865, UK
4
School of Information Technology and Electrical Engineering, The University of Queensland, Brisbane, QLD 4000, Australia
5
Imaging Technology, Translational Research Institute, Brisbane, QLD 4000, Australia
*
Author to whom correspondence should be addressed.
Academic Editor: Brian D. Ross
Tomography 2021, 7(3), 323-332; https://doi.org/10.3390/tomography7030029
Received: 24 May 2021 / Revised: 14 June 2021 / Accepted: 19 June 2021 / Published: 4 August 2021
Objective: Ultra-high-field B0 ≥ 7 tesla (7T) cardiovascular magnetic resonance (CMR) offers increased resolution. However, electrocardiogram (ECG) gating is impacted by the magneto-hydrodynamic effect distorting the ECG trace. We explored the technical feasibility of a 7T magnetic resonance scanner using an ECG trigger learning algorithm to quantitatively assess cardiac volumes and vascular flow. Methods: 7T scans were performed on 10 healthy volunteers on a whole-body research MRI MR scanner (Siemens Healthineers, Erlangen, Germany) with 8 channel Tx/32 channels Rx cardiac coils (MRI Tools GmbH, Berlin, Germany). Vectorcardiogram ECG was performed using a learning phase outside of the magnetic field, with a trigger algorithm overcoming severe ECG signal distortions. Vectorcardiograms were quantitatively analyzed for false negative and false positive events. Cine CMR was performed after 3rd-order B0 shimming using a high-resolution breath-held ECG-retro-gated segmented spoiled gradient echo, and 2D phase contrast flow imaging. Artefacts were assessed using a semi-quantitative scale. Results: 7T CMR scans were acquired in all patients (100%) using the vectorcardiogram learning method. 3,142 R-waves were quantitatively analyzed, yielding sensitivity of 97.6% and specificity of 98.7%. Mean image quality score was 0.9, sufficient to quantitate both cardiac volumes, ejection fraction, and aortic and pulmonary blood flow. Mean left ventricular ejection fraction was 56.4%, right ventricular ejection fraction was 51.4%. Conclusion: Reliable cardiac ECG triggering is feasible in healthy volunteers at 7T utilizing a state-of-the-art three-lead trigger device despite signal distortion from the magnetohydrodynamic effect. This provides sufficient image quality for quantitative analysis. Other ultra-high-field imaging applications such as human brain functional MRI with physiologic noise correction may benefit from this method of ECG triggering. View Full-Text
Keywords: magnetic resonance imaging; MRI scans; cardiology; 7 tesla MRI magnetic resonance imaging; MRI scans; cardiology; 7 tesla MRI
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MDPI and ACS Style

Hamilton-Craig, C.; Stäeb, D.; Al Najjar, A.; O’Brien, K.; Crawford, W.; Fletcher, S.; Barth, M.; Galloway, G. 7-Tesla Functional Cardiovascular MR Using Vectorcardiographic Triggering—Overcoming the Magnetohydrodynamic Effect. Tomography 2021, 7, 323-332. https://doi.org/10.3390/tomography7030029

AMA Style

Hamilton-Craig C, Stäeb D, Al Najjar A, O’Brien K, Crawford W, Fletcher S, Barth M, Galloway G. 7-Tesla Functional Cardiovascular MR Using Vectorcardiographic Triggering—Overcoming the Magnetohydrodynamic Effect. Tomography. 2021; 7(3):323-332. https://doi.org/10.3390/tomography7030029

Chicago/Turabian Style

Hamilton-Craig, Christian, Daniel Stäeb, Aiman Al Najjar, Kieran O’Brien, William Crawford, Sabine Fletcher, Markus Barth, and Graham Galloway. 2021. "7-Tesla Functional Cardiovascular MR Using Vectorcardiographic Triggering—Overcoming the Magnetohydrodynamic Effect" Tomography 7, no. 3: 323-332. https://doi.org/10.3390/tomography7030029

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