The diagnostic capability of using tissue intrinsic micro-Raman signals to obtain biochemical information from human esophageal tissue is presented in this paper. Near-infrared micro-Raman spectroscopy combined with multivariate analysis was applied for discrimination of esophageal cancer tissue from normal tissue samples. Micro-Raman spectroscopy measurements were performed on 54 esophageal cancer tissues and 55 normal tissues in the 400-1750 cm −1 range. The mean Raman spectra showed significant differences between the two groups. Tentative assignments of the Raman bands in the measured tissue spectra suggested some changes in protein structure, a decrease in the relative amount of lactose, and increases in the percentages of tryptophan, collagen and phenylalanine content in esophageal cancer tissue as compared to those of a normal subject. The diagnostic algorithms based on principal component analysis (PCA) and linear discriminate analysis (LDA) achieved a diagnostic sensitivity of 87.0% and specificity of 70.9% for separating cancer from normal esophageal tissue samples. The result demonstrated that near-infrared micro-Raman spectroscopy combined with PCA-LDA analysis could be an effective and sensitive tool for identification of esophageal cancer.
In this work we demonstrate a photoacoustic system which can identify the deformation of blood vessels under external pressure. Using photoacoustic imaging method, the vessel internal diameter can be derived from the peak-to-peak time interval of the laser (532nm) induced the photoacoustic signals. Comparisons with the actual vessel inter diameter show that the relative deviation is less than 4%, which proves the validity of this method. Interestingly, we find that the axial diameter of the blood vessel and the blood volume increase monotonously with increasing transient pressure, and the laser-induced photoacoustic signal is mainly contributed by the blood inside the vessel. Our results suggest a new way for continuous monitoring of the deformation of blood vessels under pressure.
Ultrasound-modulated optical tomography is a proiinising and noninvasive method for biomedical imaging. The advantage of this technology is its combination of optical contrast and ultrasonic resolution. In order to reconstruct the tissue imaging effectively and reliably,
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