Integrated micro-endoscopy system for simultaneous fluorescence and optical-resolution photoacoustic imaging

Area of Science:

• Biomedical Optics
• Medical Imaging
• Microscopy

Background:

• Simultaneous visualization of cellular components and microvasculature is crucial for disease diagnosis and research.
• Existing micro-endoscopy techniques often lack the resolution or simultaneous multi-modal imaging capabilities required for comprehensive analysis.

Purpose of the Study:

• To develop and validate an integrated micro-endoscopy system combining fiber-based optical-resolution photoacoustic microscopy (F-OR-PAM) and fluorescence micro-endoscopy.
• To enable simultaneous, label-free imaging of microvasculature and fluorescently labeled cellular structures with high resolution.

Main Methods:

• Integrated system with fiber-based real-time C-scan F-OR-PAM (7 µm resolution) and a fluorescence micro-endoscopy subsystem.
• Utilized a 532-nm fiber laser for F-OR-PAM and a 447.5-nm diode laser for fluorescence imaging.
• Employed topical proflavine as a fluorescent contrast agent, sharing the same light path to minimize absorption bleaching.

Main Results:

• Achieved simultaneous imaging of cellular morphology and microvascular structure in live murine models.
• Demonstrated co-registered cellular resolution imaging with F-OR-PAM structural information.
• Proflavine's low absorption at 532 nm prevented bleaching by the photoacoustic excitation source.

Conclusions:

• The integrated system provides a powerful tool for virtual biopsy, enabling visualization of angiogenesis and drug effects.
• Potential applications include studying anti-cancer drug efficacy and various other diseases at the cellular and microcirculatory levels.