In vivo Characterization of Colored Tattoo Ink Distribution in Human Skin Using Noninvasive Two-Photon Tomography Combined with Fluorescence Lifetime Imaging Microscopy

The TPE-FLIM technique enables in vivo visualization of epidermal dendritic cells and dermal fibroblasts, which are otherwise undetectable using conventional optical methods without staining. This method holds significant potential for clinical dermatology by offering insights into cellular uptake, accumulation, and long-term effects of tattoo inks, thereby supporting the management of tattoo-related complications.