Surface extraction from three dimensional ultrasound

This paper presents a system for acquiring three dimensional ultrasound data and extracting surfaces of the examined structures. The acquisition is performed freehand with a PC-based two-dimensional ultrasound machine and an optical tracker. The extraction of surfaces from ultrasound data is normally inhibited by speckle, shadowing and gaps in the acquired data. A new method is developed that extracts a surface directly from the irregularly spaced, noisy freehand ultrasound data. The freehand data is first interpolated with radial basis functions, and then a mesh is formed along an isosurface of the functional interpolation. The ability of radial basis functions to smooth speckle and extrapolate across gaps is demonstrated on a series of experiments with phantoms and human tissue in a water bath. The experiments also show the ability to create continuous and realistic surfaces from scans that require multiple sweeps over a structure.