Abstract: Our previous studies show that mid-FTIR spectroscopy can be used to distinguish malignant oral tissue from normal tissue under in vitro condition. Here, an in-situ FTIR spectroscopic measurement was performed to record FTIR spectra of normal and malignant oral tissues including salivary gland, tongue, parotid gland, submandibular gland etc. during clinical examination. The FTIR spectra of various oral tissues were acquired when an ATR probe linked to the FTIR spectrometer via mid-IR optical fibers was pressed on the tissues of the patients. For example, a patient(male, 76 years old) with tumor on the left parotid and the corresponding normal tissue on the right parotid were measured and obvious differences were observed. The spectral features of normal tissue and tumor are in good agreement with the criteria established in our previous work. (1) 1 389 cm^-1 band is quite strong in tumor, while the corresponding band in normal tissue is weaker than 1 452 cm^-1 band. (2) In normal tissue, 1 250 cm^-1 band is stronger, but the 1 250 cm^-1 band disappeared in the skin of malignant tissue. The above results demonstrate that in vivo FTIR spectra are in good agreement with our previous results obtained under in vitro condition. We believe that in vivo FTIR spectroscopy, providing the first-hand information concerning whether the suspected tissue is cancerous or not, is helpful for doctors in clinical activity.

Key words: Mid-IR fiber optics, FTIR, Malignancy tumor of oral tissue, In vivo and in situ detection