Image registration based 3D TEE-EM calibration

Real-time 3D trans-esophageal echo (TEE) is being integrated into routine clinical practice for minimally invasive cardiac therapy. Electromagnetically (EM) tracking of the TEE probe inside the body may facilitate intraprocedural heart surgery and therapy on a beating heart. This requires an accurate calibration between the 3D TEE and the EM tracking system. The objective of calibration is to find the transformation that converts the coordinates of voxels in ultrasound volumes into the coordinate system of a position sensor attached to the TEE probe. An image registration based ultrasound calibration method is presented and validated using phantoms. The experiments indicate a post-calibration image reconstruction precision of 1.56 mm and accuracy of 0.85 mm (relative accuracy of 1.86%), and TRE of 2.37 mm. The potential impact of this work is that it can provide an easy to use calibration for clinical use.