A pilot study on magnetic navigation for transcatheter aortic valve implantation using dynamic aortic model and US image guidance

Purpose   In this paper, we propose a pilot study for transcatheter aortic valve implantation guided by an augmented magnetic tracking system (MTS) with a dynamic aortic model and intra-operative ultrasound (US) images. Methods    The dynamic 3D aortic model is constructed from the preoperative 4D computed tomography, which is animated according to the real-time electrocardiograph (ECG) input of patient. Before the procedure, the US probe calibration is performed to map the US image coordinate to the tracked device coordinate. A temporal alignment is performed to synchronize the ECG signals, the intra-operative US image and the tracking information. Thereafter, with the assistance of synchronized ECG signals, the spatial registration is performed by using a feature-based registration. Then the augmented MTS guides the surgeon to confidently position and deploy the transcatheter aortic valve prosthesis to the target. Results   The approach was validated by US probe calibration evaluation and animal study. The US calibration accuracy achieved $1.37\pm 0.43\, \text{ mm}$ , whereas in the animal study on three porcine subjects, fiducial, target, deployment distance and tilting errors reached $3.16\pm 0.55\,\text{ mm}$ , $3.80\pm 1.83\,\text{ mm}$ , $3.13\pm 1.12\,\text{ mm}$ and $5.87\pm 2.35^{\circ }$ , respectively. Conclusion   Our pilot study has revealed that the proposed approach is feasible and accurate for delivery and deployment of transcatheter aortic valve prosthesis.