WFUMB Guidelines and Recommendations for Clinical Use of Ultrasound Elastography: Part 1: Basic Principles and Terminology

Abstract

Conventional diagnostic ultrasound images of the anatomy (as opposed to blood flow) reveal differences in the acoustic properties of soft tissues (mainly echogenicity but also, to some extent, attenuation), whereas ultrasound-based elasticity images are able to reveal the differences in the elastic properties of soft tissues (e.g., elasticity and viscosity). The benefit of elasticity imaging lies in the fact that many soft tissues can share similar ultrasonic echogenicities but may have different mechanical properties that can be used to clearly visualize normal anatomy and delineate pathologic lesions. Typically, all elasticity measurement and imaging methods introduce a mechanical excitation and monitor the resulting tissue response. Some of the most widely available commercial elasticity imaging methods are 'quasi-static' and use external tissue compression to generate images of the resulting tissue strain (or deformation). In addition, many manufacturers now provide shear wave imaging and measurement methods, which deliver stiffness images based upon the shear wave propagation speed. The goal of this review is to describe the fundamental physics and the associated terminology underlying these technologies. We have included a questions and answers section, an extensive appendix, and a glossary of terms in this manuscript. We have also endeavored to ensure that the terminology and descriptions, although not identical, are broadly compatible across the WFUMB and EFSUMB sets of guidelines on elastography (Bamber et al. 2013; Cosgrove et al. 2013).

Does motion affect liver stiffness estimates in shear wave elastography? Phantom and clinical study

“…Recent technological advances have enabled liver-fibrosis staging using noninvasive ultrasound techniques, such as elastography, which provides an estimation of liver stiffness [1,2]. Conventional ultrasound-elastography techniques or strain imaging evaluate how tissues respond to a static compressive force and provide a qualitative map of elasticity [3].…”

Assessment of the arterial stiffness in patients with acute ischemic stroke using longitudinal elasticity modulus measurements obtained with Shear Wave Elastography.

“…These results indicate that the circular elastic modulus of the artery was higher and the arterial stiffness was increased in patients with AIS. In addition, the longitudinal elastic modulus of the artery was found to be approximately three times higher than the circular elastic modulus [12]. The longitudinal modulus and the circumferential modulus of the arterial wall therefore indicated different circumstances.…”

The EFSUMB website, a great source for ultrasound information and education

“…The first elastography guidelines worldwide were introduced and published by EFSUMB in 2013 [14] followed by WFUMB guidelines [15][16][17].…”

“…The WFUMB Publications Committee was quite active during the last years. In addition to the WFUMB 2015 guidelines on elastography (basic principles [15], liver [17] and breast [16] more papers have been prepared and successfully published. The WFUMB guideline projects (steering committee: Richard Barr, David Cosgrove and Christoph F Dietrich) on prostate [56] and the The WFUMB guideline project on thyroid [57] have been both recently published.…”