"Label-free Molecular Imaging for Histopathology: New Opportunities for Improving Cancer Detection and Staging"

Francisco Robles, Ph.D.
Assistant Professor
Wallace H. Coulter Department of Biomedical Engineering
Georgia Tech

Label-free optical imaging methods with molecular sensitivity and high spatial resolution have emerged as powerful tools for identifying disease, since they can probe a number of important endogenous biochemical properties without destroying the samples or even disrupting the biological environment.First, we will describe pump-probe microscopy, an emerging nonlinear optical technique based on femtosecond transient spectroscopy, and its application to quantitatively image the biochemical composition of melanin in melanocytic lesions using thin, unstained tissue sections. The unprecedented biochemical information provided by this method is used as an indicator of melanocyte activity, which in turn reflects the status of melanocytic lesions. Results have shown significant promise in differentiating melanomas from benign melanocytic lesions (e.g., differentiating cutaneous melanomas from cutaneous melanocytic nevi, vulvar melanomas form atypical genital nevi and melanotic macules, and conjunctival melanoma from primary acquired melanosis). Our results also show that the biochemical composition predicts metastatic potential of invasive cutaneous melanomas with high specificity and better sensitivity than sentinel lymph node biopsy, the current gold standard. Finally, we will outline novel methods for extracting more detailed quantitative information from other molecules known to play an important role in cancer, including FAD, NADH, DNA, RNA, cytochromes, tryptophan, elastin, and collagen. Applications to other types of cancer will be discussed.