Clinical Usefulness of Optical Skin Biopsy

Traditional biopsy requires the removal, fixation, and staining of tissues from the human body. Its procedure is invasive and painful. Non-invasive in vivo optical biopsy is thus required, which should provide non-invasive, highly penetrative, three-dimensional (3D) imaging with sub-micron spatial resolution. Optical biopsy based on scanning two-photon fluorescence microscopy (TPFM) is a good method for biopsy of skin due to its high lateral resolution, low out-of-focus damage, and intrinsic three-dimensional (3D) section capability. However current technology still presents several limitations including low penetration depth, in-focus cell damages, and multi-photon phototoxicity due to high optical intensity in the 800 nm wavelength region, and toxicity if exogenous fluorescence markers were required. We study the harmonics optical biopsy of a human skin sample using a femtosecond Cr:forsterite laser centered at 1230 nm. Higher harmonics generation is known to leave no energy deposition to the interacted matters due to their energy-conservation characteristic. This energy-conservation characteristic provides the "noninvasive" nature desirable for clinical imaging. In our study, we will evaluate the clinical applications of optical skin biopsy using harmonic generation microscopy.