Shear modulus imaging with 2-D transient elastography

TLDR

Time‑resolved 2‑D transient elastography measures displacements induced by low‑frequency shear waves to characterize soft tissue elasticity. The paper introduces a novel apparatus that combines a low‑frequency vibrating device with a 128‑element linear ultrasonic array capable of ultrafast imaging (up to 10 000 fps) to follow shear wave propagation in real time. The system employs two rods driven by electromagnetic vibrators to generate a large‑amplitude, quasi‑linear shear wave, captures the resulting spatio‑temporal data with the array, and applies an inversion algorithm to reconstruct the shear modulus map. Initial experimental results on tissue‑equivalent phantoms show that the method can successfully recover shear modulus maps.

Abstract

In previous works, we have shown that time-resolved 2-D transient elastography is a promising technique for characterizing the elasticity of soft tissues. It involves the measurement of the displacements induced by the propagation of low frequency (LF) pulsed shear waves in biological tissues. In this paper, we present a novel apparatus that contains a LF vibrating device surrounding a linear array of 128 ultrasonic transducers that performs ultrafast ultrasonic imaging (up to 10,000 frames/s) and that is able to follow in real time the propagation of a LF shear wave in the human body. The vibrating device is made of two rods, fixed to electromagnetic vibrators, that produce in the ultrasonic image area a large amplitude shear wave. The geometry has been chosen both to enhance the sensitivity and to create a quasi linear shear wave front in the imaging plane. An inversion algorithm is used to recover the shear modulus map from the spatio-temporal data, and the first experimental results obtained from tissue-equivalent materials are presented.