Recent applications of near-infrared spectroscopy in cancer diagnosis and therapy.

In recent years, near-infrared spectroscopy (NIRS) has gained importance for non-invasive or minimally invasive diagnostic applications in cancer. This technology is based on differences of endogenous chromophores between cancer and normal tissues using either oxy-haemoglobin or deoxy-haemoglobin, lipid or water bands, or a combination of two or more of these as diagnostic markers. These marker bands provide a basis for the diagnosis and therapy monitoring of several cancers. Various applications also use advances in NIR fluorescence spectroscopy which is based on exogenous contrast-enhancing agents. In this review the literature published during the last seven years has been assessed. It will provide an overview on the importance of the NIRS tools in cancer pathology, and in the near future it is envisaged to play a crucial role in cancer diagnosis, treatment decisions, and defining therapeutic drug levels.

Infrared spectroscopic examination of aqueous humor.

OBJECTIVE: The aim of this study was to report on a new technique for examining aqueous humor. PARTICIPANTS: Aqueous humor samples obtained from 198 patients (cataract: n=66 eyes; age-related macular degeneration [AMD]: n=66; diabetic macular edema: n=66) were in vitro examined by mid infrared spectroscopy. After training and validating the technique, 66 samples were taken for the final independent prediction. RESULTS: In computerized analysis of the spectrometric data, 22 (100%) cataract eyes were diagnosed as the cataract group, 17 (77%) diabetic macular edema eyes were diagnosed as the diabetic macular edema group, and 14 (64%) eyes with AMD were diagnosed as the AMD group. Mid infrared spectrometry could statistically significantly (P=0.004) differentiate between the 3 study groups. CONCLUSIONS: Mid infrared spectroscopic examination of aqueous humor may be able to differentiate eyes with cataract, AMD, or diabetic macular edema.

Non-invasive measurement of intraocular pressure by near-infrared spectroscopy.

PURPOSE: To assess a new non-contact method for non-invasive measurement of intraocular pressure (IOP) using near-infrared spectroscopy. DESIGN: Experimental study. METHODS: Eleven porcine eyes were cannulated into the anterior chamber by a needle connected with a water column. Measuring the near-infrared spectrum in diffuse reflectance out of the anterior chamber by near-infrared spectroscopy, IOP was determined and compared with the height of the water column which was varied between 0 cm and 100 cm. RESULTS: In total, 363 near-infrared spectrometric measurement values were obtained. Correlating the near-infrared spectrometric measurements with the height of the water column showed a relationship with a correlation coefficient of r(2) = .858 and a steepness of the regression line of .96. CONCLUSIONS: The results of the present pilot study suggest that near-infrared spectrometric tonometry may present a new technology for non-invasive and non-contact IOP measurement.

Near-infrared fiber optic spectroscopy as a novel diagnostic tool for the detection of pancreatic cancer.

We have investigated the application of near-infrared (NIR) fiber-optic spectroscopy for the diagnosis of pancreatic cancer. Cluster analysis of the Fourier transformed near-infrared (FTNIR) fiber-optic spectra of surgically resected pancreatic tumor tissues allowed discrimination of tumor from normal tissue with high sensitivity and specificity. The sensitivity of the method using spectral information of the CH stretching first overtone region (5951-5608 cm(-1)) was 83.3% with a specificity of 83.3%. Based on the CH stretching second overtone region (8605-7938 cm(-1)) we could achieve a sensitivity of 88.9% and specificity of 72.2%. These findings suggest that NIR spectroscopy offers the potential for minimally invasive in-vivo diagnosis of pancreatic cancer.

Infrared spectroscopy: a new diagnostic tool in Alzheimer disease.

Biological markers play an evolving role in the diagnosis of Alzheimer disease (AD). We compare conventional measurements of cerebrospinal fluid (CSF) tau and beta-amyloid(1-42) proteins to a novel approach - Fourier transformed infrared (FT-IR) spectroscopy - a simple technique derived from chemical and physical sciences that characterizes intramolecular bonds. For automatic diagnostic analysis, we developed an artificial neural network (ANN). We examined 71 patients with a clinical diagnosis of AD and 66 controls. beta-Amyloid(1-42) was decreased (sensitivity 80% and specificity 78%); tau was elevated (sensitivity 76% and specificity 88%) in CSF of AD patients. The combined tau/beta-amyloid(1-42) quotient was able to distinguish healthy from diseased subjects with 99% sensitivity and 86% specificity. The ANN could separate FT-IR spectroscopy data with 88.5% sensitivity and 80% specificity. FT-IR spectroscopy proved to be cost-effective and simple to perform. Diagnostic sensitivity and specificity is in the range of CSF tau and beta-amyloid(1-42) protein analysis. Larger sample numbers for ANN training and validation could increase diagnostic accuracy and thus prove to be a useful screening tool.

CH-overtone regions as diagnostic markers for near-infrared spectroscopic diagnosis of primary cancers in human pancreas and colorectal tissue.

We have investigated the application of near-infrared spectroscopy for detection of human primary pancreatic and colorectal cancers. Spectra from cancerous and normal tissue were collected from a total of 37 surgically resected pancreatic and colorectal patient tissue specimens using a fibre-optic probe. Major spectral differences were observed in the CH-stretching first (6,000-5,400 cm(-1)) and second overtone (9,000-7,900 cm(-1)) regions. By use of artificial neural networks, linear discriminant analysis, and cluster analysis as pattern-recognition methods the spectra were classified into cancerous and normal tissue groups with accuracy up to 89%. We also explored differences between the spectra obtained from colorectal and pancreatic tissue. Spectral data from cancerous and normal tissue were classified organ-specifically into four groups with accuracy between 80 and 83%. Our results indicate that CH-overtone regions, besides serving as diagnostic markers for NIR spectroscopic diagnosis of primary human pancreas and colorectal cancers, are also useful for elucidating differences between the spectra obtained from colorectal and pancreatic cancerous tissue.