The tissue acetowhitening effect in acetic acid instillation procedure is a simple and economic method for neoplasia detection and has been clinically utilized since 1925. It is suspected that the optical property (e.g. scattering) change in acetowhitening is due to coagulation of intracellular proteins, but no experimental proof has been reported yet. In this work, we use third-harmonic generation (THG) and two-photon excited fluorescence (TPEF) to investigate the acetowhitening phenomenon induced by acidic acid in live mammalian cells without labeling. We studied the acetowhitening effect with different acetic acid concentrations and the co-localized TPEF and THG imaging on tryptophan and NADH at subcellular-level reveals that the acetowhitening phenomenon is highly related with proteins involved in metabolic pathways in the nucleus and cytoplasm in live cells.
KEYWORDS: Raman spectroscopy, In vivo imaging, Tissues, Near infrared, Diagnostics, Endoscopy, Imaging systems, Medical research, Tissue optics, Medicine
The purpose of this study was to investigate the feasibility of applying a rapid near-infrared (NIR) Raman
endoscopy system coupled with narrow band imaging technique for distinguishing dysplasia from normal
gastric mucosa tissue during clinical gastroscopy.
The purpose of this study is to apply near-infrared (NIR) Raman spectroscopy and classification and regression tree (CART) techniques for identifying molecular changes of tissue associated with cancer transformation. A rapid-acquisition NIR Raman system is utilized for tissue Raman spectroscopic measurements at 785-nm excitation. 73 gastric tissue samples (55 normal, 18 cancer) from 53 patients are measured. The CART technique is introduced to develop effective diagnostic algorithms for classification of Raman spectra of different gastric tissues. 80% of the Raman dataset are randomly selected for spectral learning, while 20% of the dataset are reserved for validation. High-quality Raman spectra in the range of 800 to 1800 cm−1 are acquired from gastric tissue within 5 s. The diagnostic sensitivity and specificity of the learning dataset are 90.2 and 95.7%; and the predictive sensitivity and specificity of the independent validation dataset are 88.9 and 92.9%, respectively, for separating cancer from normal. The tissue Raman peaks at 875 and 1745 cm−1 are found to be two of the most significant features to discriminate gastric cancer from normal tissue. NIR Raman spectroscopy in conjunction with the CART technique has the potential to provide an effective and accurate diagnostic means for cancer detection in the gastric system.
In this report, the diagnostic ability of near-infrared (NIR) Raman spectroscopy for identifying the malignant tumors from normal tissues in the larynx was studied. A rapid NIR Raman system was utilized. Multivariate statistical techniques were employed to develop effective diagnostic algorithms. Raman spectra in the range of 800-1,800 cm-1 differed significantly between normal and malignant tumor tissues. The diagnostic algorithms can yielded a diagnostic sensitivity of 92.9% and specificity 83.3% for separating malignant tumors from normal laryngeal tissues. NIR Raman spectroscopy with multivariate statistical techniques has a potential for the non-invasive detection of malignant tumors in the larynx.
Raman spectroscopy is a molecular vibrational spectroscopic technique that is capable of optically
probing the biomolecular changes associated with diseased transformation. The purpose of this study was
to explore near-infrared (NIR) Raman spectroscopy for identifying precancer (dysplasia) from normal
gastric mucosa tissues. High-quality Raman spectra in the range of 800-1800 cm-1 can be acquired from
gastric tissue within 5 seconds. Raman spectra showed significant differences between normal and
dysplastic tissue, particularly in the spectral ranges of 850-900, 1,200-1,290 and 1,500-1,800 cm-1 which
contained signals related to hydroxyproline, amide III and amide I of proteins, and C=C stretching of
lipids, respectively. The ratio of Raman intensities at 875 to 1,450 cm-1 provided good differentiation
between normal and dysplastic gastric tissue (unpaired Students' t-test, p<0.001), indicating that NIR
Raman spectroscopy has a great potential for the non-invasive diagnosis of dysplasia in the stomach.
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