Atrial fibrillation is an electrical defect in the upper chambers of heart that causes the atria to quiver rapidly, reducing the heart’s ability to pump blood. It is the most common sustained cardiac arrhythmia, affecting nearly 1% of the population. Fibrillation starts with electrical triggers originating at the pulmonary veins that then continuously circulate around the atria.
To prevent the triggers from reaching the atria, patients can undergo pulmonary vein isolation therapy. This can be achieved by a variety of methods, including most recently, cryoballoon ablation. In this case, a balloon is inflated and pressed against the pulmonary vein opening and nitrous oxide is injected into the balloon to cryogenically ablate tissue.
Regardless of the method of ablation, approximately 1/3 patients still experience AF post-therapy. To investigate this, a contrast-enhanced MR sequence that can image both angiography and scar by sharing K-space data was developed. This provides multiple benefits including:
- Faster acquisition for 3D scar images
- Accurate atrial segmentation on angiography images
- Simplified co-registration between angiography/scar images
The high contrast at the blood-atrial border of the angiography images makes segmentation simple. The borders are then directly transferred to the LGE images and expanded to extract the atrial wall.