Detection and quantification of true 3D motion components of the myocardium using 3D speckle tracking in volumetric ultrasound scans: simulations and initial experimental results
We present a new method for detecting and tracking tissue motion in 3D. The method is based on the concept of tracking speckle patterns in 3D using the sum absolute difference (SAD) technique. One potential application of this method is to study the 3D motion of various regions of interest in myocardial tissue using volumetric ultrasound scans of the heart. This could be of great value in assessing the viability of the myocardium. Simulations of 3D speckle patterns were obtained for the real-time ultrasound volumetric scanner developed at Duke University. Volumes of data were studied in pairs. Motion was simulated as whole voxel translations in 3D. A kernel volume was selected and a larger surrounding search volume was then defined. The kernel volume was compared to al possible matching sub- volumes in the search volume using the SAD technique. After the best match was found, the 3D components of motion were calculated by measuring the relative shift of the best match sub-volume from the location of the kernel volume the process was repeated until a 3D map of motion for the first frame was obtained. The performance of the proposed tracking method as a function of the SNR was the plotted for each direction. Experiments were performed to evaluate the performance of the method in vitro. A tissue mimicking materials was imaged using a 5MHz piston transducer translated in 2D to obtain multiple volumes with known shifts. The tracking method was applied and its performance with different shift values was evaluated. The calculated shift values highly matched the true shift values within a small jitter error.