4D Flow MRI Characterization of Left Atrial Vortical Flow in Atrial Fibrillation Following Catheter Ablation

Figures

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  Figure 1. Flow diagram depicting selection of participants and exclusion due to insufficient imaging quality, giving rise to the final study sample.

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  Figure 2. Summary of steps involved in data preparation and image analysis: (A) Sample images derived from 4D flow MRI following correction protocol. (B) Visualization of left heart blood flow dynamics. (C) Time-averaged rendering of phase-contrast magnetic resonance angiography, from which the left atrium (LA) is manually demarcated in successive sections to obtain a 3D segmentation. (D) Vortex volumes derived from LA segmentations using the λ2 method, and vorticity values obtained by averaging LA vorticity over the cardiac cycle. Panel D adapted with permission from Ref. [12]. Copyright © 2019, International Society for Magnetic Resonance in Medicine, published by Wiley Periodicals, Inc.

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  Figure 3. Time-averaged LA vorticity values in pre-ablation, post-ablation, and control participants. Data shown are estimated marginal means adjusted for age and sex. Error bars represent ± 1 standard error of the mean (SEM).

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  Figure 4. Representative visualizations of vorticity before and after pulmonary vein isolation in a 62-year-old male (Panels (a,b)) and 59-year-old male patient (Panels (c,d)) with paroxysmal atrial fibrillation. Images represent maximum intensity projections of vorticity in 3D left atrial segmentations, with warmer colours corresponding to greater vorticity values.

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  Figure 5. LA vortex volumes averaged across the cardiac cycle in pre-ablation, post-ablation, and control participants. Data shown are estimated marginal means adjusted for age and sex. Error bars represent ± 1 SEM.

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  Figure 6. Maximum LA vortex volumes across the cardiac cycle, in pre-ablation, post-ablation, and control participants. Data shown are estimated marginal means adjusted for age and sex. Error bars represent ± 1 SEM.