Determination of scan-plane motion using speckle decorrelation: Theoretical considerations and initial test

The correlation function of the echo signal intensities at detectability via spatial and frequency compounding [2–5]. These a fixed region on a series of B-mode images is directly related to the speckle reduction methods involve the averaging of images in change of speckle patterns between these images. An indication is which the speckle pattern has been changed. Recently, assessment given here of how the rate of the change of that correlation function of blood flow and, potentially, perfusion has been investigated can be used to estimate the scan-plane motion in any direction relaby use of decorrelation of the Doppler signal with time at one tive to the imaged tissue or other material. In this first implementation location in the image [6]. In this article we use the speckle correlait is assumed that the statistical properties of the echo signals follow tion between corresponding points in a series of scan planes those of a complex circular Gaussian, and the case is considered of for an alternative purpose: to determine the relative scan-plane diffusely scattering tissue with many fine particles per resolution cell positions, orientations, and motions. This may be important for and with no phase distortion. The method is applied to data from a the three-dimensional registration of ultrasonic images, or the one-dimensional linear array and initial results are presented for scandetection and correction for tissue motion. ning a tissue-mimicking phantom in the elevational direction of the The speckle pattern on conventional B-mode images is caused transducer. Experimental results are in good agreement with the predictions. The current method should provide a good indication of the by the phase-sensitive detection of the scattering from random local rate of scan-head motion in those tissues in which the normalinhomogeneities in the acoustic properties of biological tissue in ized correlation function of the echo signal intensities behaves, or can the resolution cell of the transducer. When the scan plane is be made to behave, as it would for a medium with uniform acoustic moved slowly, the intensities of time domain echo signals at one properties and containing many, randomly distributed, pointlike scatdistance along one echo line changes, producing a change in the terers, although application might be made to other situations where speckle pattern observed at that location on the B-mode images. a deterministic condition exists for the correlation between images We analyze the second-order statistical properties of the echo taken at differing locations within a volume. q 1997 John Wiley & Sons, signal intensity from a given depth as a function of time or Inc. Int J Imaging Syst Technol, 8, 38–44, 1997 image frame number, instead of tracking the speckle patterns in