Method and apparatus for providing real-time calculation and display of tissue deformation in ultrasound imaging

Abstract

An ultrasound system and method for calculation and display of tissue deformation parameters are disclosed. An ultrasound acquisition technique that allows a high frame rate in tissue velocity imaging or stain rate imaging is employed. The tissue deformation parameter strain is determined by an accumulation of stain rate estimates for consecutive frames over an interval. The interval may be a triggered interval generated by, for example, an R-wave in an ECG trace. The strain calculation may be improved by moving the sample volume from which the stain rate is accumulated from frame-to-frame according to the relative displacement of the tissue within the original sample volume. The relative displacement of the tissue is defined by the instantaneous tissue velocity of the sample volume. An estimation of strain rate based upon a spatial derivative of tissue velocity is improved by adaptively varying the spatial offset, dr. The spatial offset, dr, can be maximized to cover the entire tissue segment (e.g., heart wall width) while still keeping both of the sample volumes at each end of the offset within the tissue segment. This nay be accomplished by determining whether various parameters (e.g., grayscale value, absolute power estimate, magnitude of the autocorrelation function with unity temporal lag and/or magnitude of strain correlation) of the sample volumes within in the spatial offset are above a given threshold.