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Segmented radial cardiac MRI during arrhythmia using retrospective electrocardiogram and respiratory gating
Author(s) -
Chava Raghuram,
Assis Fabrizio,
Herzka Daniel,
Kolandaivelu Aravindan
Publication year - 2019
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.27533
Subject(s) - heartbeat , image quality , sinus rhythm , gating , qrs complex , medicine , cardiac imaging , electrocardiography , cardiac arrhythmia , atrial fibrillation , cardiac cycle , cardiology , artificial intelligence , nuclear medicine , computer science , image (mathematics) , physiology , computer security
Purpose To improve segmented cardiac MRI image quality during arrhythmia. Methods Electrocardiogram (ECG) and respiratory waveforms were recorded during imaging. Imaging readouts were retrospectively classified into heartbeat‐types based on the RR interval of the current and preceding beats, QRS morphology, and respiratory phase. Image data were sorted by these classifiers to generate separate cine images of different heartbeat‐types during sinus rhythm and arrhythmia. A simulation study evaluated the efficiency of K‐space sampling over a range of heart rhythms, heart rates, and respiratory rates. In vivo imaging was performed in volunteers with sinus rhythm, swine with arrhythmia simulated by pacing, and a human subject with spontaneous premature beats. Results K‐space sampling uniformity and image quality incrementally improve with additional occurrences of the desired normal sinus or arrhythmia heartbeat‐type. To approach the image quality of breath‐hold imaging, sufficiently restrictive gating parameters are required. Compared with real‐time imaging, retrospective gated images had reduced noise and improved sharpness while maintaining desired cine temporal resolution. Variations of cardiac function between arrhythmia heartbeats could be observed in arrhythmia imaging cases that are not captured by conventional segmented imaging. Conclusion Retrospective ECG and respiratory gating permits imaging of various heartbeats during arrhythmia with fewer resolution restrictions compared to real‐time imaging. For a fixed imaging time, imaging quality depends on frequency of the imaged heartbeat‐type. Imaging additional heartbeats permits incremental improvement in image quality.