Vibro-acoustography: An imaging modality based on ultrasound-stimulated acoustic emission

TLDR

Possible applications include medical imaging and material evaluation. We describe theoretical principles of an imaging modality that uses the acoustic response of an object to a highly localized dynamic radiation force of an ultrasound field. USVA applies a low‑frequency ultrasound force to induce sinusoidal vibration of an object, and the resulting acoustic emission is detected to generate images that encode both ultrasonic and viscoelastic properties. The study demonstrates that the emitted acoustic field correlates with the incident ultrasound pressure, yielding a point‑spread function and experimental images with ~700 µm resolution, high contrast, high SNR, and sensitivity to nanometer‑scale motions.

Abstract

We describe theoretical principles of an imaging modality that uses the acoustic response of an object to a highly localized dynamic radiation force of an ultrasound field. In this method, named ultrasound-stimulated vibro-acoustography (USVA), ultrasound is used to exert a low-frequency (in kHz range) force on the object. In response, a portion of the object vibrates sinusoidally in a pattern determined by its viscoelastic properties. The acoustic emission field resulting from object vibration is detected and used to form an image that represents both the ultrasonic and low-frequency (kHz range) mechanical characteristics of the object. We report the relation between the emitted acoustic field and the incident ultrasonic pressure field in terms of object parameters. Also, we present the point-spread function of the imaging system. The experimental images in this report have a resolution of about 700 microm, high contrast, and high signal-to-noise ratio. USVA is sensitive enough to detect object motions on the order of nanometers. Possible applications include medical imaging and material evaluation.