Optical spectroscopy offers unique opportunities for a label-free investigation of tissues at the molecular level to identify the variety of diseases. To transfer spectroscopic analysis from the scientific laboratories to clinical environment, fiber optic probes are required as optical bridges between the equipment and tissue.
We developed single and combined fiber optic probes for the following set of spectroscopy methods: Mid IR-absorption, Raman scattering, Diffuse NIR-reflection, and auto-fluorescence. We benchmarked these methods and selected the optimal one (or their combination), that differentiate between healthy and malignant tissue, based on optical spectra. We tested cancer-normal tissue pairs of human body such as colon, kidney, brain as well as cartilages with and without injuries. Equines cartilage samples with and without osteoarthritis were tested as well. Obtained spectral data were evaluated by multivariate discrimination analysis to enable clear separation of malignant and normal tissues. Data fusion was revealed a synergic effect resulted in increasing of sensitivity, specificity and accuracy (up to 98% for kidney cancer).
Medical fiber optics as a part of laboratory and clinical diagnostic tools, surgical instrumentation and endoscopy should satisfy modern biomedical requirements. The flexibility, small size, bio-compatibility and feasibility to use sterilisable or disposable parts allow to apply fiber optic probes in clinical environment both ex-vivo and in-vivo.
To enable spectroscopic differentiation cancer and normal tissue, we developed and applied various single and combined fiber optic probes using key spectroscopy methods such as Raman scattering, Mid IR-absorption, Diffuse NIR-reflection, and fluorescence in order to compare them and select the best combination for malignant detection of tissue in clinical environment.
All four spectroscopic methods have been tested on biopsies of health and malignant tissues (colon and kidney) and bioliquids (serum, plasma and urine) of patients before and after surgery. The tiny Raman probe with 1.5 mm diameter has been developed for experimental ex-vivo tests. Further multivariate data analysis of spectroscopic data, both individual techniques and their combinations has provided a reliable cancer recognition for colon and kidney biopsies. The best synergic gain was observed of combining Mid IR-absorption and fluorescence spectroscopy (98% Sensitivity vs 63% or 88% for fluorescence or Mid IR-absorption correspondingly). Based on obtained results, both techniques were implemented within the same fiber probe to provide a simultaneous measurement of exactly the same spot at the sample surface. An innovative combi Fluo-ATR probe was designed, fabricated and tested.
Diffuse NIR-reflection and fluorescence spectroscopy as the fastest measurement techniques were used for investigation of surgically removed colorectal tissue samples in a few minutes after resection. Taking into account the necessity of rapid measurement process, we developed multispectral NIR-UV probe that enables efficient excitation and collection of NIR diffuse reflectance and fluorescence spectra of the same point. Needle probe design with diameter 0.7 mm allows to penetrate in some depth of tissue and obtain most reliable spectra avoiding artefacts related to surface drying. Multivariate data analysis proved the increased sensitivity of methods combination in one dataset (94% Sensitivity vs 85% or 85% for fluorescence or NIR reflection correspondingly).