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Park, Yoon, Yang, and Ahn: Cardiac Magnetic Resonance Imaging Using Multi-physiological Intelligent Trigger System
Original Article

Journal of the Korean Society of Magnetic Resonance in Medicine 2014; 18(3): 244-252.

Published online: 30 September 2014

DOI: https://doi.org/10.13104/jksmrm.2014.18.3.244

Cardiac Magnetic Resonance Imaging Using Multi-physiological Intelligent Trigger System

Jinho Park, Jong-Hyun Yoon, Young-Joong Yang, Chang-Beom Ahn

Department of Electrical Engineering, Kwangwoon University, Seoul, Korea.

Address reprint requests to: Chang-Beom Ahn, Ph.D., Department of Electrical Engineering, Kwangwoon University, 21, Gwangun-ro, Nowon-gu, Seoul 139-701, Korea. Tel. 82-2-940-5148 Fax. 82-2-909-3159, cbahn@kw.ac.kr

Received 2 July 2014       Revised 23 July 2014       Accepted 24 July 2014

Copyright © 2014 Journal of the Korean Society of Magnetic Resonance in Medicine

(open-access):

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Purpose

We proposed a multi-physiological signals based real-time intelligent triggering system(MITS) for Cardiac MRI. Induced noise of the system was analyzed.

Materials and Methods

MITS makes cardiac MR imaging sequence synchronize to the cardiac motion using ECG, respiratory signal and second order derivative of SPO2 signal. Abnormal peaks due to arrhythmia or subject's motion are rejected using the average R-R intervals and R-peak values. Induced eddy currents by gradients switching in cardiac MR imaging are analyzed. The induced eddy currents were removed by hardware and software filters.

Results

Cardiac MR images that synchronized to the cardiac and respiratory motion are acquired using MITS successfully without artifacts caused by induced eddy currents of gradient switching or subject's motion or arrhythmia. We showed that the second order derivative of the SPO2 signal can be used as a complement to the ECG signals.

Conclusion

The proposed system performs cardiac and respiratory gating with multi-physiological signals in real time. During the cardiac gating, induced noise caused by eddy currents is removed. False triggers due to subject's motion or arrhythmia are rejected. The cardiac MR imaging with free breathing is obtained using MITS.

Keywords: Multi-physiological Intelligent Trigger System (MITS), Cardiac MRI, ECG gating, SPO2 gating Respiratory gating

Figures and Tables

Fig. 1
Block diagram of MITS.
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Fig. 2
Flow chart of the program to generate a trigger signal to spectrometer from multi-physiological signals is shown.
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Fig. 3
Screen for the operation of MITS is shown.
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Fig. 4
Acquired ECG signals and corresponding spectra: (a) ECG signal without application of the gradient fields. (b) Spin echo imaging with TR of 500ms for single slice imaging (fn = 2 Hz). (c) Spin echo imaging with TR of 1000 ms and the number of slices of 10 (fn = 10 Hz). The eddy-current induced noise peaks (fn) are marked with small rectangles.
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Fig. 5
Acquired ECG signals and corresponding spectra during various gradient echo imaging. (a) Spoiled gradient echo imaging with TR of 500ms and the number of slices of 10 (fn = 20 Hz). (b) Balanced SSFP imaging with TR of 4.71 ms for single slice imaging (fn = 213 Hz). (c) Spiral SSFP imaging with TR of 5ms for single slice imaging (fn = 200 Hz). The eddy-current induced noise peak (fn) is marked with a small rectangle.
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Fig. 6
Comparison of cardiac CINE MR images are shown with free breathing (a), breath-hold (b), and respiratory gating (c). Three cardiac phases are shown in vertical direction. ECG gating was applied for all the cases (a)-(c). Note blurring in the heart wall in (a) in contrast to clear boundaries in (b) and (c).
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Fig. 7
Comparison of cardiac CINE MR images are shown with ECG gating (a) and SPO2 gating (b). Respiratory gating was applied both in (a) and (b). Three cardiac phases are shown in vertical direction.
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