Evaluating the Improvement in Shear Wave Speed Image Quality Using Multidimensional Directional Filters in the Presence of Reflection Artifacts

• Published in: IEEE transactions on ultrasonics, ferroelectrics, and frequency control Vol. 63; no. 8; pp. 1049 - 1063
• Main Authors: Lipman, Samantha L., Rouze, Ned C., Palmeri, Mark L., Nightingale, Kathryn R.
• Format: Journal Article
• Language: English
• Published: United States IEEE 01-08-2016; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: 2-D shear wave speed; 3-D shear wave elastography; 3-D shear wave speed; 3-D stiffness reconstruction; acoustic radiation force; Acoustics; biomechanics; biomedical ultrasonics; directional filter; elasticity; Elasticity Imaging Techniques - methods; Elasticity Imaging Techniques - standards; Estimation; Force; Image Processing, Computer-Assisted - methods; Image quality; Image reconstruction; Imaging; Lesions; Phantoms, Imaging; propagation; Quality; Reconstruction; Reflected waves; Reflection; shear wave elasticity imaging; shear wave propagation; Signal Processing, Computer-Assisted; simulations; Solid modeling; Sound waves; Three-dimensional displays; ultrasonic imaging; 3-D stiffness reconstruction; shear wave elasticity imaging; elasticity; shear wave propagation; 3-D shear wave elastography; biomedical ultrasonics; directional filter; biomechanics; imaging; simulations; 3-D shear wave speed; propagation; 2-D shear wave speed; acoustic radiation force; acoustics; ultrasonic imaging
• ISSN: 0885-3010; 1525-8955
• DOI: 10.1109/TUFFC.2016.2558662

Shear waves propagating through interfaces where there is a change in stiffness cause reflected waves that can lead to artifacts in shear wave speed (SWS) reconstructions. Two-dimensional (2-D) directional filters are commonly used to reduce in-plane reflected waves; however, SWS artifacts arise from both inand out-of-imaging-plane reflected waves. Herein, we introduce 3-D shear wave reconstruction methods as an extension of the previous 2-D estimation methods and quantify the reduction in image artifacts through the use of volumetric SWS monitoring and 4-D-directional filters. A Gaussian acoustic radiation force impulse excitation was simulated in phantoms with Young's modulus (E) of 3 kPa and a 5-mm spherical lesion with E = 6, 12, or 18.75 kPa. The 2-D-, 3-D-, and 4-D-directional filters were applied to the displacement profiles to reduce inand out-of-plane reflected wave artifacts. Contrast-to-noise ratio and SWS bias within the lesion were calculated for each reconstructed SWS image to evaluate the image quality. For 2-D SWS image reconstructions, the 3-D-directional filters showed greater improvements in image quality than the 2-D filters, and the 4-D-directional filters showed marginal improvement over the 3-D filters. Although 4-D-directional filters can further reduce the impact of large magnitude out-of-plane reflection artifacts in SWS images, computational overhead and transducer costs to acquire 3-D data may outweigh the modest improvements in image quality. The 4-D-directional filters have the largest impact in reducing reflection artifacts in 3-D SWS volumes.