MR-guided cardiac radiofrequency ablation with catheter-tracked local MR lesion monitoring
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KeywordsCatheter Guidance Catheter Tracking SSFP Cine Guidance Platform SSFP Cine Sequence
MR-guided electrophysiology (MR-EP) for the treatment of arrhythmia has the potential advantages of improved soft tissue contrast navigation and visualization of ablation-induced tissue changes. In the past, the development of MR-conditional EP catheters and an appropriate image guidance platform have represented major obstacles. The aim of this work was to establish and evaluate a catheter-guided approach that allows monitoring of radiofrequency (RF) ablation at the electrode tip.
This approach was first tested in a phantom and then assessed in-vivo in a 40kg pig. Four discrete RF lesions (40W, 1min) were applied on the posterior right atrial wall. Edema and wall thickness were monitored for each catheter tip location over the first 5min and at 15, 30, and 45min. The T2-signal in the wall was normalized to the ventricular myocardial signal to determine a relative enhancement.
Catheter tracking at 10Hz was reliable for all catheter tip orientations, resulting in smooth catheter guidance and accurate automatic scan plane planning.
The in-vivo results are shown in Figure 1. The position of the catheter tip (Figure 1b) is confirmed by cardiac cine SSFP imaging (Figure 1c). The images for measurement of the wall thickness and the signal enhancement are shown in Figure 1d+e, before and 30min after ablation. The wall thickness and T2-signal enhancement at two ablation sites increase to approx. twice the original value during the first 30min (Figure 1f+g).
A new technique to quantify wall thickness and T2-signal enhancement at the catheter tip has been demonstrated. This allows for fast and efficient monitoring of catheter-based RF ablation.
This work has been funded by the Techology Strategy Board (TS/G02142/1) and the Wellcome/EPSRC Medical Engineering Centre.
This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.