A freehand 3D ultrasound imaging system using open-source software tools with improved edge-preserving interpolation

Ultrasound imaging is widely employed in various medical procedures. Most ultrasound procedures are performed with conventional 2D ultrasound systems, but visualizing the 3D anatomy using 2D ultrasound images is often challenging. This paper describes the use of open-source software tools to develop a freehand system for synthesizing high-quality 3D ultrasound volumes using electromagnetic tracking. In the proposed system, the spatial transformation between the 2D ultrasound images and the electromagnetic sensor attached to the ultrasound transducer was performed using an accurate spatial calibration method. A new interpolation method, called the edge-preserving distance-weighted (EPDW), is employed to reconstruct the 3D ultrasound volumes. The performance of the system is evaluated by performing a set of phantom experiments. The results showed that the reconstructed 3D ultrasound volumes have sub-millimeter accuracy. Moreover, the ultrasound volumes synthesized using the EPDW method demonstrated improved edge preservation compared with a previous interpolation method.