In this paper, we proposed a co-registered dual-modality photoacoustic (PA) and ultrasoundimaging technique to simultaneously map the functional and structural information ofhuman tongue, which has the potential to detect and diagnose tongue cancer in early stage. Theimaging probe comprises a 20-MHz side-view focused transducer for ultrasound imaging and PAdetection, a light path constructed by a multimode optical ¯ber, and a prism for PA illumination.Phantom experiments were conducted to evaluate the performance of the system includingpenetration depth, spatial resolution and signal-to-noise ratio. In vivo imaging of animaltumor and human tongue was carried out to show the feasibility of the proposed technique todetect tumor lesions in human tongue. The results of phantom and in vivo experiments suggestthat the proposed technique has the potential to detect the early-stage cancer lesions in humantongue.[pdf]

Heng Guo, Weizhi Qi, Ming He, Jian Rong, and Lei Xi*, Journal of Innovative Optical Health Sciences, DOI: 10.1142/S1793545818500086

In this letter, we present a high-resolution photoacoustic endomicroscopy (PAEM) probe based on a microelectromechanical systems (MEMS) scanning mirror. The built-in optical assembly consists of a 0.7 mm graded-index (GRIN) lens for light focusing and a Ф1 mm MEMS mirror to reflect and scan the beam. A miniaturized unfocused ultrasound transducer with a center frequency of 10 MHz is used for photoacoustic detection. Sharp blades, carbon fibers and black tapes were utilized to evaluate the performance of the system. In vivo mouse ears and resected rectums were imaged to further demonstrate the feasibility of this probe for potential biological and clinical applications.[pdf]

Heng Guo, Chaolong Song, Huikai Xie and Lei Xi*, Optics Letters, Vol. 42, No. 22, 2017, 4615-4618.