Global Time Delay 2 D Estimation in Ultrasound Elastography

6 June 2016 6 GLOBAL TIME DELAY 2D ESTIMATION IN ULTRASOUND ELASTOGRAPHY. Hoda Sadat Hashemi1,2, Hassan Rivaz1,2. 1Department of Electrical and Computer Engineering, Concordia University, 1455 De Maisonneuve Blvd. W., Montreal, Quebec, H3G1M8, CANADA; 2PERFORM Center, 7200 Sherbrook St. W., Montreal, Quebec, H4B1R6, CANADA. Background: Correlation methods are commonly used for Time-Delay Estimation (TDE) of tissue displacement. Large correlation windows utilize more information and reduce the estimation variance, but result in significant signal decorrelation and decrease the spatial resolution. Furthermore, most correlation techniques only estimate axial strain because of the poor resolution of ultrasound data in the lateral direction. An attractive alternative approach to correlation-based methods is minimization of a regularized cost function. These methods exploit the prior information that tissue deformation is smooth, and therefore are robust to signal decorrelation [1]. A disadvantage of these methods is their computational complexity, and as such, they are not suitable for real-time implementation. Previous work [2] proposed a real-time method for optimization of the cost function, but only exploited individual RFlines at during each optimization, which results in artifacts in the form of vertical streaks (Fig. 1).