In vivo optically encoded photoacoustic flowgraphy.

Area of Science:

• Biomedical Optics
• Photoacoustic Imaging
• Flow Measurement

Background:

• Accurate measurement of fluid flow is crucial in various scientific and medical applications.
• Existing photoacoustic flow imaging methods have limitations in resolution and speed.
• Optical encoding offers a novel approach for enhanced photoacoustic measurements.

Purpose of the Study:

• To introduce and validate a novel optically encoded photoacoustic flow imaging method.
• To demonstrate the capability of the method for quantitative flow speed measurements.
• To assess the performance of the technique in both phantom and in-vivo settings.

Main Methods:

• Utilized optical-resolution photoacoustic microscopy.
• Employed an intensity-modulated continuous-wave laser for photothermal encoding of the flowing medium.
• Generated photoacoustic waves using a pulsed laser to image the encoded heat pattern.
• Calculated flow speeds via cross-correlation analysis.

Main Results:

• Successfully validated the optically encoded photoacoustic flow imaging method in phantoms.
• Achieved accurate flow speed measurements in phantoms across a range of 0.23 to 11 mm/s.
• Demonstrated in-vivo applicability by measuring venous blood flow speed in a mouse ear.

Conclusions:

• The presented optically encoded photoacoustic flow imaging method provides a robust and accurate approach for quantifying flow dynamics.
• This technique holds potential for various biomedical applications requiring precise microflow measurements.
• Further development could enhance its capabilities for more complex flow scenarios.