High-quality reconstruction of arrhythmic cardiac cycles
© Wundrak et al. 2016
Published: 27 January 2016
The current clinical standard in cardiac functional MRI is retrospectively gated cine MRI. The technique is relying on a regular heart beat and cardiac cycles showing substantial deviation from the mean heart rate are excluded, often causing reduced image quality and completely suppressing arrhythmic cycles. We introduce a new correlation based self-gating approach enabling reconstruction of the entire cardiac motion including arrhythmic sections at high image quality.
Study Population and MRI protocol
Dynamic short axis time-resolved cardiac data sets were acquired at 1.5T from three patients (2 women, 1 man, aged 79 to 83 years) with known severe cardiac arrhythmia resulting in varying cardiac cycle length even during a short 6.3 second breathhold. All data were obtained with a 32-element cardiac coil applying a tiny golden angle (Ψ7≈23.628°)  radial balanced SSFP sequence with TR / TE = 2.6 / 1.3 ms, flip angle = 60°, resolution 1.72 mm2, slice thickness 8 mm, and acquisition matrix 2122.
The data were reconstructed applying the proposed non-uniform image-based self-gating technique (nuSG ), real-time compressed sensing reconstruction (GRASP ), and classical retrospective cardiac self-gating (SG). M-mode data were calculated from the short-axis images for better appreciation of arrhythmic cycles.
The visibility of the arrhythmic cycles was assessed in the M-mode data. Furthermore, end-systolic and end-diastolic endocardial areas and image sharpness was compared between the investigated reconstruction techniques.
In conclusion, a new self-gating method was proposed that allows CMR of arrhythmic patients at high image quality, maintaining the information of the arrhythmic cycles in the resulting images. Compared to real-time techniques, the nuSG technique provides higher SNR and image sharpness.
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