The accuracy and precision of estimating tissue displacements from ultrasonic images

In many medical ultrasound imaging systems, clinical data are often presented in the form of tissue displacement and tissue velocity maps. The accuracy of tissue displacement estimates obtained using a well-established cross-correlation, speckle tracking technique is determined. The accuracy of the cross-correlation technique is evaluated as function of three parameters: (1) the magnitude of the tissue displacement; (2) the size of the region being tracked; and (3) of host tissue type. Three different sample types (porcine liver, porcine muscle and woolen sea sponge) are used to study the effect of different scattering media on displacement estimates. For identically sized target regions and displacements, liver samples produce estimates with the largest uncertainties. For all three sample types, the accuracy and precision of displacement estimates deteriorates with increasing sample displacements and decreasing target dimensions