Addressing spatiotemporal distortion of high-speed tissue motion in B-mode ultrasound

The sequential excitation of transducer elements in linear ultrasound arrays can produce distorted images in B-mode since the A-lines in an image frame are not captured at the same time. If the imaged tissue is moving laterally during image acquisition, substantial distortion can occur and lead to errors in tissue displacement and velocity measurements, particularly for high-speed tissue motion such as in injury biomechanics tests. A method for correcting for this distortion in tracked time-series displacement data was developed for systems in which each A-line of the image is completed at a time proportional to its lateral position across the transducer linear array. The proposed method involves estimating more precisely the time at which each point in the image was captured, rather than relying on the time elapsed between image frames to estimate timing. The developed method was evaluated using results from motion tests of human dura imaged using a Vevo 2100 Imaging System at a frame rate of 865 frames per second. At tissue speeds ranging from 0.2 m s(-)1 to 2.3 m s(-1), tracking of tissue displacement without correction resulted in mean displacement measurement error of 17%. Correction using proposed methods reduced error to a mean of 2%. This correction concept has the potential to improve the accuracy of velocity or displacement measurements in any B-mode imaging application where tissue velocity is high relative to ultrasound sweep velocity including in injury biomechanics and cardiac biomechanics research.