Tissue characterization of acute lesions during cardiac magnetic resonance-guided ablation of cavo-tricuspid isthmus-dependent atrial flutter: a feasibility study

Figures

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  Figure 1. Overview of CMR sequences to assess the tissue characteristics of the ablation region, in which the arrows indicate the CTI ablation region, extending from the tricuspid annulus towards the inferior caval vein: (A) 3D whole-heart SSFP (one frame from 3D dataset), (B) SSFP cine imaging in RAO view (still end-diastolic frame), (C + G) T2WI at the CTI (arrow) demonstrates higher signal intensity and increased wall thickness on post-ablation imaging (G) compared with pre-ablation (C), (E) first-pass perfusion during contrast infusion shows persisting hypo-enhancement in the ablation area (still frame from Supplementary data online, Video S1), (F) 2D dark-blood LGE image with hyper-enhancement in the ablated area and a central area of hypo-enhancement.,(D + H) T1 mapping is performed pre- and post-ablation (detailed figure of a qualitative assessment is shown in Figure 3); CMR, cardio magnetic resonance; CTI, cavo-tricuspid isthmus; LGE, late gadolinium enhancement; SSFP, steady-state free-precession; T2WI, T2-weighted imaging.

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  Figure 2. Boxplots indicating the distribution of T1 mapping values of regions with and regions without additional radiofrequency lesions. Left: absolute T1 value of the region post-ablation. Middle: increase in absolute T1 value after ablation. Right: percentage increase in T1 value after ablation.

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  Figure 3. Qualitative assessment of T1 mapping, examples of three patients (A–C). Anatomical images (a, b) and the corresponding colour-coded T1 maps (c, d) pre-ablation and post-ablation. The outlined target ablation area in image a–d corresponds to the zoom view in the bottom row e–h, respectively. In the target region, the blue areas (low T1 values) suggest fatty structures within the right atrial wall, and green areas the thin endocardium. On the post-ablation colour-coded image (d), there are also areas of yellow and red within the target ablation area suggestive of higher T1 values. The arrow in C indicates the artefacts from the adjacent catheter.

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  Figure 4. Inter-observer agreement of T1 mapping. Blant–Altman plot (above) with the mean T1 value of the two observers and the inter-observer difference, bias = 12 ms, the limits of agreement −102 and 126 ms. Scatter plot (below) of the measured T1 values by both observers, with the line of perfect agreement.