Ultrasound calibration for unique 2.5D conical images.

Intracardiac echocardiography (ICE) systems are routinely used in percutaneous cardiac interventions for interventional and surgical navigation. Conavi's Foresight ICE is a new ICE system that uses a mechanically rotating transducer to generate a 2D conical surface image in 3D space, in contrast to the more typical side-firing phased array. When combined with magnetic tracking technology, this unique imaging geometry poses new calibration challenges and opportunities. Existing ultrasound calibration methods are designed for 2D planar images and cannot be trivially applied to unique 2.5D conical surface images provided by the Foresight ICE system. In this work a spatial and temporal calibration technique applied to the unique case of conical ultrasound image data is described and validated. Precision of calibration parameters is used to quantify the validation of our calibration method and the overall system accuracy is validated using point source and sphere centroid localization. We report a maximum error of 5.07 mm for point reconstruction accuracy and 1.94 mm for sphere centroid localization accuracy.