Photoacoustic flow velocity imaging based on complex field decorrelation.

Area of Science:

• Biomedical Optics
• Medical Imaging
• Fluid Dynamics

Background:

• Photoacoustic (PA) imaging visualizes blood flow in microvasculature.
• Ultrasound speckle decorrelation velocimetry accurately measures blood flow velocity in mouse brains.
• Integrating these methods enables simultaneous flow and oxygenation imaging.

Purpose of the Study:

• To adapt ultrasound speckle decorrelation velocimetry for photoacoustic imaging.
• To quantify blood flow velocity using PA imaging.
• To demonstrate angle-independent flow velocity measurement.

Main Methods:

• Utilized a pulsed laser diode and PA imaging.
• Employed a quantitative method based on normalized first-order field autocorrelation of PA signal fluctuations.
• Tested in an ink tube phantom and chicken embryo chorioallantoic membrane microvasculature.

Main Results:

• Established a relationship between signal decorrelation time and flow speed.
• Demonstrated successful estimation of flow velocities in phantoms and biological tissues.
• Validated the PA flow analysis as an angle-independent method.

Conclusions:

• The developed PA velocimetry method accurately measures blood flow.
• This technique allows for simultaneous functional parameter extraction (e.g., oxygenation).
• The angle-independent nature enhances its applicability in diverse microvascular imaging scenarios.