Video-Rate Molecular Imaging in Vivo with Stimulated Raman Scattering

TLDR

Optical imaging with molecular specificity offers high spatial resolution and sensitivity, and stimulated Raman scattering (SRS) microscopy provides label‑free vibrational imaging, but in vivo use has been limited by poor light collection through thick tissues and motion blur from slow imaging. The study aims to enable in vivo SRS imaging by greatly improving backscattered signal collection and accelerating imaging to video rate. The authors enhance backscattered signal collection and accelerate imaging three orders of magnitude to achieve video‑rate performance. The method enables label‑free in vivo imaging of water, lipid, and protein in skin and maps penetration pathways of topically applied drugs in mice and humans.

Abstract

Optical imaging in vivo with molecular specificity is important in biomedicine because of its high spatial resolution and sensitivity compared with magnetic resonance imaging. Stimulated Raman scattering (SRS) microscopy allows highly sensitive optical imaging based on vibrational spectroscopy without adding toxic or perturbative labels. However, SRS imaging in living animals and humans has not been feasible because light cannot be collected through thick tissues, and motion-blur arises from slow imaging based on backscattered light. In this work, we enable in vivo SRS imaging by substantially enhancing the collection of the backscattered signal and increasing the imaging speed by three orders of magnitude to video rate. This approach allows label-free in vivo imaging of water, lipid, and protein in skin and mapping of penetration pathways of topically applied drugs in mice and humans.