Ultrasonic-heating-encoded photoacoustic tomography with virtually augmented detection view

Area of Science:

• Biomedical Imaging
• Acoustic Physics
• Thermal Engineering

Background:

• Photoacoustic (PA) imaging faces limitations with arbitrarily oriented objects due to wave propagation and limited detection angles.
• Existing PA imaging techniques may miss crucial features when objects are not optimally aligned with detectors.

Purpose of the Study:

• To develop a universally applicable ultrasonic thermal encoding approach to overcome angular limitations in PA imaging.
• To enhance the detection and imaging of arbitrarily shaped or oriented structures in PA tomography.

Main Methods:

• Exploited the temperature dependence of the Grueneisen parameter to thermally encode specific voxels using focused ultrasound.
• Developed a mathematical model for thermally encoded PA tomography, followed by numerical simulations and experimental validation.
• Utilized the increased PA amplitude from encoded voxels, which propagates omnidirectionally, for improved detection.

Main Results:

• Demonstrated that ultrasonic thermal encoding increases PA amplitude from targeted voxels while leaving adjacent voxels unaffected.
• Successfully validated the efficiency of ultrasonic thermal encoding through simulations and experiments.
• Achieved full-view in vivo vascular imaging, significantly outperforming traditional linear-array PA tomography for arbitrarily oriented vessels.

Conclusions:

• Ultrasonic thermal encoding is a promising technique for overcoming angular limitations in PA imaging.
• The method enables full-view imaging of biomedical structures, including deep tissues and tumor margins.
• This approach offers enhanced imaging capabilities for arbitrarily oriented features, improving diagnostic potential.