Optical resolution photoacoustic microendoscopy with ultrasound-guided insertion and array system detection

Abstract

Using a 0.8-mm-diameter image guide fiber bun- dle consisting of 30,000 single-mode fibers and an external linear array transducer, we demonstrate a dual-mode photo- acoustic system capable of ultrasound-guided micro- endoscope insertion and photoacoustic imaging. The array optical resolution photoacoustic microendoscopy (AOR- PAME) system is designed to visualize the placement of the distal end of an endoscopy probe several centimeters into tissue, transmit scanning focused laser pulses into tis- sues via the fiber bundle, and acquire the generated photo- acoustic signals. A ytterbium-doped fiber laser is tightly focused and is scanned across the proximal tip of the image guide fiber bundle using a two-dimensional galva- nometer scanning mirror system. The end of the fiber bundle is used in contact mode with the object. The capabilities of AOR-PAME are demonstrated by imaging carbon fiber net- works embedded in tissue-mimicking phantoms and the ears of a 60-g rat. The lateral resolution and signal-to- noise ratio are measured as 9 μm and 40 dB, respectively.