Differentiation of tumors of the upper respiratory tract using optical metabolic imaging

Tumors of the upper respiratory tract are the sixth most common tumor entity in humans. Currently a dedicated screening method enabling a direct onsite diagnosis is missing. This can lead to delayed diagnoses and worse outcomes of the patients. A label-free optical method enabling a direct distinction between healthy tissue, dysplastic tissue and cancerous tissue would be an ideal tool for the detection of tumors of the upper respiratory tract. In this study we used fluorescence lifetime imaging (FLIM) of endogenous NADH and FAD to image the metabolic state in different tissue samples of the upper aerodigestive tract (UADT). Due to the different metabolic pathways that are active in healthy and tumor cells their metabolic states differ significantly. FLIM datasets of tissue samples from 25 patients were recorded directly after surgery ex vivo in a special tissue culture medium at 37°C on a dedicated microscope using multiphoton excitation. By calculating the fluorescence-lifetime redox ratio (FLIRR) based on the FLIM measurements, we were able to visualize the metabolic state of the cells. We found that healthy tissue, dysplastic tissue and cancerous tissue showed significant differences in the FLIRR. This study suggests that the FLIRR might be a sensitive and robust parameter for the differentiation of cancerous and pre-cancerous UADT tissue. Based on our results an endoscopic system for in vivo measurements is currently being developed that could facilitate the use of optical metabolic imaging as a tool for an early tumor diagnosis.

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Publication History

Article published online:
10 June 2020