Handheld endomicroscope using a fiber-optic harmonograph enables real-time and in vivo confocal imaging of living cell morphology and capillary perfusion

Confocal laser endomicroscopy provides high potential for noninvasive and in vivo optical biopsy at the cellular level. Here, we report a fully packaged handheld confocal endomicroscopic system for real-time, high-resolution, and in vivo cellular imaging using a Lissajous scanning fiber-optic harmonograph. The endomicroscopic system features an endomicroscopic probe with a fiber-optic harmonograph, a confocal microscope unit, and an image signal processor. The fiber-optic harmonograph contains a single mode fiber coupled with a quadrupole piezoelectric tube, which resonantly scans both axes at ~ 1 kHz to obtain a Lissajous pattern. The fiber-optic harmonograph was fully packaged into an endomicroscopic probe with an objective lens. The endomicroscopic probe was hygienically packaged for waterproofing and disinfection of medical instruments within a 2.6-mm outer diameter stainless tube capable of being inserted through the working channel of a clinical endoscope. The probe was further combined with the confocal microscope unit for indocyanine green imaging and the image signal processor for high frame rate and high density Lissajous scanning. The signal processing unit delivers driving signals for probe actuation and reconstructs confocal images using the auto phase matching process of Lissajous fiber scanners. The confocal endomicroscopic system was used to successfully obtain human in vitro fluorescent images and real-time ex vivo and in vivo fluorescent images of the living cell morphology and capillary perfusion inside a single mouse. A fiber-optic microscopy system collects real-time imaging data with high resolution from within the tissue of living organisms. Endoscopically-coupled microscopes systems have become increasingly commonplace, but these systems often suffer from stability issues and trade-offs in terms of imaging speed and resolution. Researchers led by Ki-Hun Jeong of the KAIST Institute of Health Science and Technology have now developed an endomicroscope based on a system known as a Lissajous fiber scanner, a design that delivers excellent stability and uniform image quality. The researchers demonstrate the capacity to obtain micron-resolution imaging data from cultured cells, isolated organs, and live mice at a rate of 10 frames per second. The device is compact and designed for handheld use, and the researchers already envision opportunities to further improve imaging depth and resolution in the near future.