Using image-based regression to acquire freehand 3D ultrasound

Describes a new technique for estimating the out-of-plane distances between neighbouring 2D B-scan images. Probabilistic analysis of the speckle signal intensity leads to a distance estimation algorithm based on linear regression. The quality of fit to the regression line indicates the reliability of the distance estimate. The new technique can be used to determine the three out-of-plane degrees-of-freedom of scan plane motion. The in-plane translations and rotation can be deduced by correlating neighbouring B-scan images. As a result, the relative 3D positions of all the 2D B-scans can be calculated without the need for a position sensor attached to the ultrasound probe. The approach is useful for recording 3D data when a position sensor is not available, or for improving the local consistency of a conventional sensor-based recording.