Miniature probe for dual- modality photoacoustic microscopy and white- light microscopy for image guidance: A prototype toward an endoscope

Abstract

In this study, a novel photoacoustic microscopy (PAM) probe integrating white- light microscopy (WLM) modality that provides guidance for PAM imaging and complementary information is implemented. One single core of an imaging fiber bundle is employed to deliver a pulsed laser for photoacoustic excitation for PAM mode, which provides high resolution with deep penetration. Meanwhile, for WLM mode, the imaging fiber bundle is used to transmit two- dimensional superficial images. Lateral resolution of 7.2 μm for PAM is achieved. Since miniature components are used, the probe diameter is only 1.7- mm. Imaging of phantom and animals in vivo is conducted to show the imaging capability of the probe. The probe has several advantages by introducing the WLM mode, such as being able to conveniently identify regions of interest and align the focus for PAM mode. The prototype of an endoscope shows potential to facilitate clinical photoacoustic endoscopic applications.Integrated photoacoustic microscopy (PAM) and white- light microscopy into a miniature probe can be useful for medical imaging applications such as image guidance for PAM and endoscopy. Further, the two modalities provide complementary information. However, implementation of the probe with miniature size and high resolution has been technically challenging. The novel design of using an imaging fiber bundle and a gradient- index lens offers a simple approach to realize such a miniature probe.