In vivo dynamic process imaging using real-time optical-resolution photoacoustic microscopy.

Area of Science:

• Biomedical Optics
• Microscopy
• Photoacoustics

Background:

• Label-free imaging techniques are crucial for non-invasive biological studies.
• Real-time dynamic process imaging requires high speed and resolution.
• Optical-resolution photoacoustic microscopy (OR-PAM) offers unique contrast mechanisms.

Purpose of the Study:

• To demonstrate in vivo dynamic process imaging using a novel label-free real-time OR-PAM system.
• To achieve high-resolution visualization of microvasculature and microhemodynamics.
• To evaluate the system's performance in terms of speed, resolution, and field of view.

Main Methods:

• Development of a reflection-mode OR-PAM system utilizing a 532-nm fiber laser with a 600 kHz pulse repetition rate.
• Integration of a fast-scanning mirror system for rapid image acquisition.
• Implementation of real-time C-scan OR-PAM for dynamic microhemodynamics imaging with feedback control.

Main Results:

• Near real-time imaging (0.5 fps) of microvasculature in SCID mouse ears with micron-scale resolution over a 1x1 mm2 field of view.
• Real-time imaging (30 fps) of cardiac-induced microhemodynamics in murine microvasculature over a 250x250 μm2 field of view.
• Demonstration of sustained imaging capabilities with real-time feedback for focusing and positioning.

Conclusions:

• The developed label-free real-time OR-PAM system enables advanced in vivo dynamic imaging.
• The system provides high-resolution visualization of microvasculature and physiological processes.
• This technology holds potential for various biomedical research applications requiring non-invasive dynamic observation.