Multiview Three-Dimensional Echocardiography Image Fusion Using a Passive Measurement Arm

Three-dimensional (3D) echocardiography offers a fast and efficient way to scan and assess the structures and function of the heart. However, due to limitations inherent to 3D echocardiography such as limited field-of-view and low signal-to-noise ratio, 3D assessment of the heart is performed only in a minority of patients who undergo transthoracic echocardiography. One approach for improving the field-of-view and image quality is to scan the heart from multiple locations by moving the transducer and fusing the resulting images into a single volume, which requires 3D alignment of individual volumetric echocardiography scans. Previous approaches relied on optical or electromagnetic trackers for transducer tracking. This study proposes a passive measurement arm system for tracking the position of the ultrasound transducer and thereby aligning multiple echocardiography scans. The proposed system does not suffer from line-of-sight limitation as in the case of an optical tracking based fusion system. Additionally, in contrast to an electromagnetic based tracking system, measurement arm measurements are not affected by other ferromagnetic materials in the vicinity. The proposed approach was tested by scanning a heart phantom and fusing nine echocardiography volumes acquired from different locations. The fusion of all nine scans yielded a percentage field-of-view improvement of 98.5%.