Shear Wave Elastography

Abstract

D espite the introduction of B-mode ultrasound into regional anesthesia, no evidence suggests any reduction in the incidence of unintentional intraneural injection. 1 B-Mode ultrasound has several limitations: structures with similar scattering characteristics are difficult to differentiate; image quality is inconsistent among patients and deteriorates with age; and block needle tips are difficult to see. There is a need to quantify and characterize tissue properties and, in doing so, differentiate between intraneural and extraneural anatomy to make regional anesthesia safer. 2 One property of human tissue is elasticity-the ability of tissue, once stretched, to revert back to its original shape. elasticity is characterized as Young elastic modulus (e), the ratio of stress to strain. shear wave elastography is an ultrasound-based modality that is being investigated as a tool for the noninvasive diagnosis of breast cancer. Young modulus is displayed as a color map superimposed on a B-mode image and quantified within regions of interest.