Research Projects

SLSC Imaging

Conventional ultrasound images are formed by delay-and-sum beamforming of the backscattered echoes received by individual elements of the transducer aperture. Although the delay-and-sum beamformer is well suited for ultrasound image formation, it is corrupted by speckle noise and challenged by acoustic clutter and phase aberration. We have developed an alternative method of imaging utilizing the short-lag spatial coherence (SLSC) of the backscattered echoes. Compared with matched B-mode images, SLSC images demonstrate superior SNR and contrast-to-noise ratio in simulated and experimental speckle-generating targets, but are shown to be challenged by limited point target conspicuity. We are currently investigating the challenges and opportunities of real-time implementation of SLSC imaging.

For fast spatial coherence estimation, a C++ implementation with a MATLAB/MEX interface is provided in the GitLab code repository https://gitlab.com/dahl-us-lab/spatcov, along with example scripts. This code is free to use, and is covered by the Apache v2 license. *Please cite the following two references if this code is used to publish results*:
D. Hyun, A. C. Crowley and J. J. Dahl, "Efficient Strategies for Estimating the Spatial Coherence of Backscatter," in IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, vol. 64, no. 3, pp. 500-513, March 2017.  doi: 10.1109/TUFFC.2016.2634004
M. A. Lediju, G. E. Trahey, B. C. Byram and J. J. Dahl, "Short-lag spatial coherence of backscattered echoes: imaging characteristics," in IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, vol. 58, no. 7, pp. 1377-1388, July 2011.  doi: 10.1109/TUFFC.2011.1957



Fig. 2. Gallbladder: fundamental B-mode and corresponding SLSC-processed images. (animated GIF available, email us)


Fig. 3. Heart: fundamental B-mode and corresponding SLSC-processed images. (animated GIF available, email us)