Post-processing methodology for the multimodal study of the left atrium during atrial fibrillation

Introduction

In the context of a prospective study for the multimodal characterization of the left atrium in patients undergoing atrial fibrillation ablation, we developed a systematic pipeline to allow the co-registration and analysis of three different imaging modalities: LGE-CMR, 3D catheter-based invasive voltage maps and FDG uptake measured by PET.

Method

The software SLICER3D was choosed as the primary building block. As a free, open source software, it allows for the quick building and deployment of custom solutions thanks to its python wrapper. Several software solutions were developped in python using both the SLICER3D innate capabilities and the Vizualisation toolkit library (VTK) powerful post-processing power.

Results

Building on a previous work from Hohmann S. we developed a program allowing the importation in SLICER3D of CARTOv7 (biosense) voltage maps. Using built-in tools, 3D meshes were created from LGE-CMR and PET studies. Unto those 3D meshes, a custom program calculated a maximum intensity projection of the atrial wall along normal vectors, allowing for the creation of LGE and SUV 3D maps. Lastly, iterative point cloud registration permitted the fusion of all 3 mappings. Point-by-point test of association between low voltage, low FDG uptake and high-LGE was used.

Conclusion

We were able to fusion and do a point-by-point analysis of three different imaging studies of the left atrium in atria fibrillation: voltage maps, LGE-CMR, and PET. Software solutions developed for this post-processing pipeline are generic and could be adapted for other multimodalities studies. A prospective study using this methodology and involving patients in AF undergoing ablation is underway and will be presented at the ESC congress 2023 (Fig. 1).