Subsurface tumor progression investigated by noninvasive optical second harmonic tomography

Nonlinear optical imaging with femtosecond (10(-15)-second) laser technolog y aas used to evaluate the subsurface tumor progression in control, dysplas ia, and cancerous 7,12-dimethylbenz[a] anthracene-treated hamster cheek pou ch mucosa tissues. Two-dimensional images of hamster cheek pouch mucosa tis sues were obtained by scanning the second harmonic Signal at various sagitt al and axial positions, The spatial mapping of the second harmonic signals showed depth differentiation between normal, dysplasia, and a more advanced cancerous state, This nonlinear optical method offers a noninvasive in sit u imaging tool to the medical community.