Ultrasound-induced light guiding overcomes contrast and resolution limits in optoacoustic tomography

Intense light diffusion and attenuation through turbid biological tissues compromise the achievable depth, resolution, and contrast in optoacoustic tomography (OAT). We propose to mitigate this limitation by exploiting ultrasound waves to locally modulate the refractive index of scattering samples, effectively generating embedded light waveguides. Here, the ultrasound-induced waveguides enhanced light delivery into deep targets, achieving up to 110% improvement in contrast-to-noise ratio of OAT images at a depth of eight mean free scattering paths. Furthermore, ultrasound-mediated light focusing enables breaking through the acoustic diffraction limit by attaining 25 μm spatial resolution via localization OAT without the need for external circulating contrast agents. These findings demonstrate the potential of ultrasound-induced light guiding for enabling label-free super-resolution OAT with enhanced contrast and depth.