Tracking and correcting for organ motion artifacts in ultrasound tomography systems

Motion artifacts have been identified as a problem in medical tomography systems. This problem, however, is well known in other types of real-time imaging systems such as radar satellites and sonars. In this case it has been found that the application of an overlap processing scheme [J. Acoust. Soc. Am. 86, 158–171 (1989)] increases the resolution of a phased array imaging system and corrects for motion artifacts as well. Reported results have shown that the problem of correcting motion artifacts in synthetic aperture applications is centered on the estimation of a phase correction factor. This correction factor is then used to compensate for the temporal phase differences between sequential sensor-array measurements in order to synthesize the spatial information coherently. This paper describes an approach which tracks the organ motion and allows the artifacts to be isolated in ultrasound tomography systems. Two sources are utilized so that two sets of projections are generated that are identical in space but separated in time. Then the spatial overlap correlator processing scheme is used to synthesize the 2-D projection data coherently. This provides the desired phase correction factor, which compensates for the phase fluctuations caused by the subject’s organ-motion effects and tracks the organ motion.