Clinical feasibility of duplex photoacoustic and ultrasound pulse-echo imaging using photoacoustic transmit pulses

Photoacoustic (PA) imaging is an emerging modality offering promise for cancer diagnosis, therapy planning, and monitoring response. The images show optically absorbing tissue structures based on detection of ultrasound signals after laser irradiation. For clinical use, PA imaging is best implemented with freehand pulse-echo scanning in a single device, so that PA signals may be displayed in real-time within the anatomical context. For this purpose, PA frames must be interleaved with pulse-echo frames. This is often not feasible with commercially available ultrasound systems. For clinical research purposes therefore, we developed a novel approach where both PA and pulse-echo images are generated photoacoustically. Our objective was to evaluate the feasibility of clinical imaging with this technique.