All-optical forward-viewing photoacoustic probe for high-resolution 3D endoscopy

Area of Science:

• Biomedical Optics
• Medical Imaging
• Surgical Technology

Background:

• Minimally invasive surgery requires advanced imaging tools for real-time guidance.
• Current endoscopic imaging lacks high-resolution 3D capabilities in the millimeter scale.

Purpose of the Study:

• To demonstrate a miniature forward-viewing endoscopic probe for high-resolution 3D photoacoustic imaging.
• To evaluate the probe's performance in imaging biological tissues and phantoms.

Main Methods:

• A 3.2 mm diameter probe incorporating a transparent Fabry-Pérot (FP) polymer-film ultrasound sensor at the distal end of an optical fiber bundle.
• Excitation laser pulses illuminate tissue, and photoacoustic waves are mapped using a 50,000-element high-density ultrasound array formed by the FP sensor.
• Sequential scanning with an interrogation laser beam addresses individual sensor elements for 2D mapping.

Main Results:

• Achieved high-resolution 3D photoacoustic imaging with a lateral resolution of 45-170 µm and vertical resolution of 31 µm at depths of 1-7 mm.
• Demonstrated excellent image fidelity in 3D reconstructions of absorbing phantoms, duck embryo microvasculature, and mouse skin.
• The probe utilizes a wide-bandwidth (34 MHz) sensor for precise spatial sampling.

Conclusions:

• The developed miniature endoscopic probe successfully provides high-resolution 3D photoacoustic imaging.
• This technology shows promise for applications in guiding laparoscopic procedures, fetal surgery, and other minimally invasive interventions.
• The probe's millimeter-scale footprint and forward-viewing capability are advantageous for intricate surgical navigation.