Combination of B-mode imaging and acousto-photonic sensing using a commercial ultrasound scanner

Abstract

The acousto-photonic imaging (API) of a turbid medium is based on the interaction of multiply scattered coherent laser light with an ultrasonic field. The two waves mix and the photons emanating from the interaction region are phase modulated at the ultrasound frequency. This technique yields information on the optical and acoustical properties of the medium, with the interaction region defined by the dimension of the ultrasonic beam. We investigated the feasibility of combining conventional B-mode ultrasound imaging and API in vitro, using a commercial medical scanner (Analogic AN2300). The AN2300 was used to both generate the B-mode images and excite API signals. Gel-based acousto-optic phantoms were fabricated; these contained imbedded targets possessing acoustical and/or optical contrast. Analogous to power Doppler measurements, B-mode images were first acquired and then used to select regions of interest within which API signals were generated. API information was then color-coded and superimposed on top of the frozen B-mode image. Preliminary results show that API signals can be excited using a commercial scanner, and serve to augment conventional B-mode images with information related to the opto-acoustic properties of the medium. [Work supported by the Center for Subsurface Sensing and Imaging Systems via NSF ERC Award Number EEC-9986821.]