Dual-foci fast-scanning photoacoustic microscopy with 3.2-MHz A-line rate

We report fiber-based dual-foci fast-scanning OR-PAM that can double the scanning rate without compromising the imaging resolution, the field of view, and the detection sensitivity. To achieve fast scanning speed, the OR-PAM system uses a single-axis water-immersible resonant scanning mirror that can confocally scan the optical and acoustic beams at 1018 Hz with a 3-mm range. Pulse energies of 45 similar to 100-nJ are sufficient for acquiring vascular and oxygen-saturation images. The dual-foci method can double the B-scan rate to 2036 Hz. Using two lasers and stimulated Raman scattering, we achieve dual-wavelength excitation on both foci, and the total A-line rate is 3.2-MHz. In in vivo experiments, we inject epinephrine and monitor the hemodynamic and oxygen saturation response in the peripheral vessels at 1.7 Hz over 2.5 x 6.7 mm(2). Dual-foci OR-PAM offers a new imaging tool for the study of fast physiological and pathological changes.

Automated summary

This study introduces a fiber-based dual-foci fast-scanning OR-PAM system that doubles the scanning rate while maintaining imaging quality. By using dual-foci method and stimulated Raman scattering, fast vascular imaging and oxygen saturation measurement are achieved, providing a new imaging tool for studying physiological and pathological changes.