Ultrathin, high-speed, all-optical photoacoustic endomicroscopy probe for guiding minimally invasive surgery

TL;DR

This paper introduces a miniaturized, high-speed all-optical photoacoustic endomicroscopy probe integrated into a 20-gauge needle for real-time, high-resolution tissue imaging to assist minimally invasive surgery.

Contribution

The work presents a novel ultrathin, high-speed PA endomicroscopy probe using wavefront shaping and microresonator ultrasound detection within a needle, enabling real-time imaging.

Findings

Achieved ~3 fps high-resolution imaging of mouse blood cells.

Enabled real-time mosaicing to expand field-of-view.

Demonstrated potential for guiding minimally invasive surgery.

Abstract

Photoacoustic (PA) endoscopy has shown significant potential for clinical diagnosis and surgical guidance. Multimode fibres (MMFs) are becoming increasing attractive for the development of miniature endoscopy probes owing to ultrathin size, low cost and diffraction-limited spatial resolution enabled by wavefront shaping. However, current MMF-based PA endomicroscopy probes are either limited by a bulky ultrasound detector or a low imaging speed which hindered their usability. In this work, we report the development of a highly miniaturised and high-speed PA endomicroscopy probe that is integrated within the cannula of a 20 gauge medical needle. This probe comprises a MMF for delivering the PA excitation light and a single-mode optical fibre with a plano-concave microresonator for ultrasound detection. Wavefront shaping with a digital micromirror device enabled rapid raster-scanning of a focused light spot at the distal end of the MMF for tissue interrogation. High-resolution PA imaging of mouse red blood cells covering an area 100 microns in diameter was achieved with the needle probe at ~3 frames per second. Mosaicing imaging was performed after fibre characterisation by translating the needle probe to enlarge the field-of-view in real-time. The developed ultrathin PA endomicroscopy probe is promising for guiding minimally invasive surgery by providing functional, molecular and microstructural information of tissue in real-time.