Second-harmonic generation (SHG) imaging is combined with coherent anti-Stokes Raman scattering (CARS) microscopy to follow the process of optical clearing in human skin ex vivo using dimethyl sulfoxide (DMSO) as the optical clearing agent. SHG imaging revealed that DMSO introduces morphological changes to the collagen I matrix. By carefully measuring the dynamic tissue attenuation of the coherent nonlinear signal, using CARS reference signals during the clearing process, it is found that DMSO reduces the overall SHG response from dermal collagen. Evidence is provided for a role of DMSO in compromising the structure of collagen fibers, associated with a reduction of the tissue's scattering properties.

Functional optical characterization of disease progression and response to therapy suffers from loss of spatial resolution and imaging depth due to scattering, impacting the ability of researchers to localize and quantify molecular processes.Here we report on the ability of dimethyl sulfoxide (DMSO) to reduce temporarily the optical scattering of skin. Data collected from in vitro phantom images and in vivo fluorescence images demonstrate the potential of this simple method to mitigate the blurring effects of scattering with topical application, which we expect will improve the accuracy and localization of in vivo molecular imaging studies. © 2009 SPIE.

Functional optical characterization of disease progression and response to therapy suffers from loss of spatial resolution and imaging depth due to scattering. Here we report on the ability of dimethyl sulfoxide (DMSO) alone to reduce the optical scattering of skin. We observed a threefold reduction in the scattering of skin with topical DMSO application. With an in vivo window chamber model, we observed a threefold increase in light transmittance through the preparation and enhanced visualization of subsurface microvasculature. Collectively, our data demonstrate the potential of DMSO alone to mitigate effects of scattering, which we expect will improve molecular imaging studies.