Label-free microendoscopy using a micro-needle imaging probe for in vivo deep tissue imaging

Area of Science:

• Biomedical Optics
• Medical Imaging
• Microscopy

Background:

• Label-free imaging techniques are crucial for minimally invasive biological tissue analysis.
• Light scattering in biological tissues limits the depth penetration of conventional imaging methods.
• Microendoscopy requires specialized probes for accessing and visualizing deep tissue structures.

Purpose of the Study:

• To develop and validate a label-free microendoscopy method using a needle-type probe for deep tissue imaging.
• To investigate the impact of illumination geometry on signal acquisition in deep tissue imaging.
• To demonstrate the feasibility of the technique for visualizing microvasculature in biological samples.

Main Methods:

• A needle-type imaging probe was constructed by inserting a GRIN lens attached to a fiber bundle into a medical-grade needle.
• An oblique back-illumination configuration was employed with the illuminating probe positioned on the tissue surface.
• Three-dimensional depth imaging was achieved by adjusting the probe's penetration depth.
• Systematic investigation of optimal illumination distance was performed.

Main Results:

• The needle probe provided direct access to deep tissue regions, overcoming limitations of light scattering.
• The method enabled label-free, three-dimensional depth imaging of biological tissues.
• Successful visualization of microvasculature deep within ex vivo and in vivo mouse brains was achieved.
• Optimal illumination conditions for signal maximization were identified.

Conclusions:

• The developed needle-type microendoscopy probe offers a minimally invasive solution for deep tissue imaging.
• The technique effectively visualizes intricate microvasculature, demonstrating its potential for preclinical research.
• This label-free approach enhances the ability to study subsurface biological structures without exogenous contrast agents.