An efficient block matching and spectral shift estimation algorithm with applications to ultrasound elastography

Abstract

An efficient block matching and spectral shift estimation algorithm for freehand quasi-static ultrasound elastography is described in this paper. The proposed method provides a balance between computational speed and robustness against displacement estimation error and bias; a fundamental aspect of elastography. The new algorithm was tested on an extensive set of simulated 1-D RF ultrasound signals, replicating various strain profiles. Additionally, real 2-D scans were conducted on an ultrasound phantom with prescribed elastic properties; the algorithm output was further validated with a comparison to a finite element model (FEM) of the phantom. Clinical data from a breast cancer study and histology slides were used to demonstrate the in vivo use of the new elastography technique. The algorithm showed a significant computational savings (at least 60 times faster) over existing spectral shift analysis methods. Accurate strain images were produced in as little as 2 s with the scope for further speed enhancements through parallel processing; making real-time implementation a future possibility. Moreover, it demonstrated a robustness toward displacement estimation error when compared with conventional gradient-based techniques, and was able to perform at high strain values (>5%) while showing relative insensitivity to various parameters settings, such as sample rate and block window size; a desirable performance for a practical clinical tool.

A Fast Peak‐Searching Algorithm for Ultrasonic Elastography

“…More recently, many two‐dimensional (2D) elasticity imaging methods were developed for achieving more robustness in larger compression situation. The block matching algorithm is a representative one of this type that first searches for regions of interest of a specific size and then finds the best matching region within a set of searched areas. The local displacement of the adjacent two frames is calculated according to the location of the best‐matching region.…”

Elastografia em imagens de ultrassom utilizando elementos de contorno.

“…Em um trabalho mais recente, DiBattista and Noble [20] apresentam um algoritmo para elastograa utilizando block matching e, em um primeiro momento, utilizam sinais de RF de ultrassom para, posteriormente, aplicar o algoritmo em imagens simuladas de ultrassom. O trabalho consiste em determinar um índice de semelhança ótimo, utilizando coeciente de correlação cruzada normalizado.…”