Multi-modal acousto-optic/ultrasound imaging of ex vivo liver tumors at 790 nm using a Sn2 P2 S6 wavefront adaptive holographic setup.

Biological tissues are very strong light-scattering media. As a consequence, current medical imaging devices do not allow deep optical imaging unless invasive techniques are used. Acousto-optic imaging is a light-ultrasound coupling technique that takes advantage of the ballistic propagation of ultrasound in biological tissues to access optical contrast with a millimeter resolution. We have developed a photorefractive-crystal-based system that performs self-adaptive wavefront holography and works within the optical therapeutic window. As it works at an appropriate wavelength range for biological tissues imaging, it was tested on ex vivo liver samples containing tumors as a pre-clinical study. Optical contrast was obtained even if acoustical one was not significant. Ultrasound image (left) and acousto-optic image (right) of a liver biopsy with tumors. Acousto-optic imaging exhibits tumors that are not detected through ultrasound.