Abstract 18568: Interfacing Fast Multi-phase Cardiac Image Registration with MRI-based Catheter Tracking for MRI-guided Electrophysiological Ablative Procedures
Background: T2-weighted cardiac MRI, performed peri-operatively during an electrophysiology procedure, can, within the acute-injury phase after RFA delivery, distinguish scar tissue from edema . Although ablated lesions are observed on MR images, the visualized lesion positions may not be well aligned with the pre-operative electrophysiological (EP) roadmap due to tissue deformation. We propose to register the lesion targets onto the EP roadmap for more accurate ablation with an MRI-compatible active catheter tracking system.
Objectives: To map the ablated lesion target accurately onto the EP roadmap based on rapid intra-operative MR images.
Methods: An intensity-based 3D image registration approach, Demons , co-registered (a) intra-operative low-resolution MR images with (b) pre-operative high-resolution MR images that construct the EP roadmap. Both can have different dimension and scanning directions obtained by a 3T-MRI scanner (Fig.A1). The computation was accelerated using graphic processing units (GPUs). A left atrial (LA) model constructed of soft silicone was used, of which the LA morphology can be varied (Fig.A2). Gadolinium contrast agents could be injected into pre-defined regions inside the LA wall (Fig. B2), simulating perioperative physiological changes at ablation landmarks (<Æ3mm), for validation of the registration (Fig.B1). Finally, MRI-compatible catheters with MR-actively-tracked micro-coils  (resolution 0.6х0.6х0.6 mm3) were used to navigate to the ablation landmarks and validate the registration (Fig.B3).
Results: The GPU-based co-registration was conducted within 2sec. It re-aligned the ablation target onto the EP roadmap with an average distance error of <3mm (n=3).
Conclusions: The proposed platform tracked EP catheters, and co-registered cardiac images in real-time, allowing for improved targeting of lesions.
Ref:  Ranjan, Circ., 2012;  Vercauteren, NeuroImage, 2009;  Schmidt, Circ., 2008.
Author Disclosures: K. Kwok: None. K. Lee: None. Y. Chen: None. W. Wang: None. Y. Hu: None. G. Chow: None. H. Zhang: None. W.G. Stevenson: None. R. Kwong: None. W. Luk: None. E.J. Schmidt: None. Z. Tse: None.
- © 2014 by American Heart Association, Inc.