Relative Elastic Modulus Imaging Using Sector Ultrasound Data for Abdominal Applications: An Evaluation of Strategies and Feasibility

Abstract

We reconstruct the elastic modulus distribution for one tissue mimicking (TM) phantom and two in vivo biopsy-confirmed liver tumors using curvilinear ultrasound echo data. Spatial distribution of the relative elastic modulus values is determined by solving an inverse problem within a region of interest (ROI). This inverse problem solution requires knowledge of the ultrasonically-measured displacement field in a uniform rectilinear grid to ensure that the resolution on the resultant relative elastic modulus elastogram will be uniform over the entire ROI. Taking advantage of a new speckle tracking algorithm, two different displacement tracking strategies are investigated: (1) sector-shaped ultrasound data were converted to ultrasound data on a rectilinear grid prior to speckle tracking and (2) axial and lateral displacements directly obtained from sector-shaped data were converted to vertical and horizontal displacements on a rectilinear grid after speckle tracking. As compared to strain elastography (SE), TM phantom results show that relative elastic modulus imaging (REMI) using Strategy 2 provided higher contrast-to-noise ratios (>300% and 25% increases as compared to SE and REMI using Strategy 1, respectively). Furthermore, in phantoms, REMI using Strategy 2 more accurately (a 1.3% difference to SWE measurements) estimated the elastic contrast ratio between the target and the background, as compared to both SE (20–25%) and REMI using Strategy 1 (4.1%). It was also observed that relative modulus elastograms were more consistent to anatomical structures visualized on corresponding B-mode images for the two in vivo liver cases. Overall, we conclude that applying REMI is feasible for abdominal organs such as the liver. Strategy 2 offered improved and consistent results for data investigated.

Building an open-source simulation platform of acoustic radiation force-based breast elastography

“…Particularly, results in Table 3 suggested that SSI offers the highest elastic contrast values as compared to SE and ARFI. This observation is consistent with the tissue -mimicking phantom results reported by Palmeri and Nightingale (Palmeri and Nightingale, 2011) and Peng et al (Peng et al , 2016). In the future, viscoelastic tissue properties will be included in this virtual elastography platform.…”

Comparison of Displacement Tracking Algorithms for in Vivo Electrode Displacement Elastography

“…If the first and last displacement vectors of the diamond stencil are different and the correlation value of the displacement vector at the center of the stencil is 0.75 or higher, then that center of the stencil is marked as a trusted seed. These seeds are then used in a modified predictive search strategy described in (Peng et al 2016). Initialized seeds from the regularized search and all displacements estimated with correlation coefficients less than 0.4 are then discarded.…”

“…In addition to displacement vector tracking and estimation, an important step for all these methods is the approach used to transform displacement data from a sector format to a rectilinear grid. Trigonometric identities using both x and y displacement vectors were used (Peng et al 2016) to generate axial and lateral displacement vectors for the sector array data. An additional post-displacement task was to localize a rectangular region of interest containing the ablated tumor region and regions of normal liver surrounding it from all the displacement tracking methods for comparison.…”

Digital image technology based on PCA and SVM for detection and recognition of foreign bodies in lyophilized powder

“…However, the research on classification recognition algorithm is not mature, and the application of its research results in the actual production line cannot achieve the desired effect. With the development of computer technology [4,5], domestic studies on the detection and classification of foreign matter inspection in pharmaceutical liquids have also made some achievements. Xiao et al [6] mainly carried out studies on detection and tracking of moving foreign matter in ampoule bottle solutions.…”