Speckle Variance Photoacoustic Microscopy for Microhemodynamic Imaging

Area of Science:

• Biomedical Optics
• Medical Imaging
• Microcirculation Research

Background:

• Photoacoustic microscopy (PAM) uses hemoglobin's optical absorption for label-free microvasculature imaging.
• Existing PAM methods provide morphological and functional data but can be limited in dynamic hemodynamic assessment.

Purpose of the Study:

• To introduce Speckle Variance Photoacoustic Microscopy (SV-PAM) for high-resolution, 3D in vivo hemodynamic imaging.
• To leverage intrinsic contrast from moving red blood cells for enhanced microvascular visualization.

Main Methods:

• Acquisition of consecutive photoacoustic B-scan frames at identical lateral positions.
• Calculation of speckle variance from these frames to identify blood perfusion and occlusion.
• In vivo imaging of microvascular occlusion and reperfusion in mouse ears.

Main Results:

• SV-PAM successfully recovered 3D hemodynamic images with capillary-level resolution.
• Accurate identification of blood perfusion and occlusion was achieved, revealing dynamic blood flow.
• High-resolution hemodynamic imaging demonstrated vascular occlusion and reperfusion dynamics.

Conclusions:

• SV-PAM provides intrinsic contrast for label-free, high-resolution 3D hemodynamic imaging of microvasculature.
• The technique enables visualization of dynamic blood flow, perfusion, and occlusion.
• SV-PAM shows significant potential for biomedical hemodynamic investigations, including stroke imaging.