A Novel Compact Linear-Array Based Photoacoustic Handheld Probe Towards Clinical Translation for Sentinel Lymph Node Mapping

Breast cancer is the leading threat to women health both in the developed and developing countries around the world. Sentinel lymph node (SLN) biopsy has become the standard of care for the staging of this disease over the past few decades. Conventional ultrasound lacks the capability to identify the SLNs. Thus, during the procedure, radioactive tracers and dyes are injected and an open surgery is required to identify the dye accumulated SLNs. As a rapidly growing technology, photoacoustic (PA) imaging is gaining widespread attention due to its excellent imaging contrast as well as high resolution for deep imaging [1, 2]. Therefore, handheld ultrasound linear array based PA systems have been developed by several groups for SLN identification over the past few years, which were demonstrated to be able to identify SLNs noninvasively, and can potentially eliminate the need for radioactive tracers and open surgeries [3]. In most of these systems, the light excitation and ultrasound detection are not designed coaxially, and thus high laser pulse energy is usually needed to produce PA images with a decent signal-to-noise ratio. For one recently reported coaxial based design, the imaging probe is very bulky and complex, making it unfriendly for clinical use and translation [4].