Raman microspectroscopy as a biomarking tool for in vitro diagnosis of cancer: a feasibility study

Abstract

AimTo elucidate whether Raman spectroscopy aided by extensive spectral database and neural network analysis can be a fast and confident biomarking tool for the diagnosis of various types of cancer.MethodsStudy included 27 patients with 11 different malignant tumors. Using Raman microscopy (RM) a total of 540 Raman spectra were recorded from histology specimens of both tumors and surrounding healthy tissues. Spectra were analyzed using the principal component analysis (PCA) and results, along with histopathology data, were used to train the neural network (NN) learning algorithm. Independent sets of spectra were used to test the accuracy of PCA/NN tissue classification.ResultsThe confident tumor identification for the purpose of medical diagnosis has to be performed by taking into account the whole spectral shape, and not only particular spectral bands. The use of PCA/NN analysis showed overall sensitivity of 96% with 4% false negative tumor classification. The specificity of distinguishing tumor types was 80%. These results are comparable to previously published data where tumors of only one tissue type were examined and can be regarded satisfactorily for a relatively small database of Raman spectra used here.ConclusionIn vitro RM combined with PCA/NN is an almost fully automated method for histopathology at the level of macromolecules. Supported by an extensive tumor spectra database, it could become a customary histological analysis tool for fast and reliable diagnosis of different types of cancer in clinical settings.

Lung neoplasm diagnostics using Raman spectroscopy and autofluorescence analysis

“…The efficiency of the proposed double-stage method of Raman diagnostics of lung neoplasms is, upon the average, by 5-10% higher in comparison with other methods of diagnostics [5,8], based on the analysis of Raman scattering. The method allows not only the detection of the pathology, but also the determination of the particular neoplasm type.…”

“…Most of the known methods of neoplasm Raman spectra analysis [7,8,22] are based on the introduction of threshold characteristics of the peak intensities at 1300-1340, 1640-1680 и 1440-1460 cm -1 . The sensitivity and specificity of the methods based on the absolute threshold characteristics rarely exceed 80%.…”

“…[5] demonstrated high efficiency of Raman scattering method in lung cancer diagnostics; the achieved sensitivity was 94 % and the specificity 92%. However, in the case of mass screening the sensitivity and the specificity of the method are essentially lower, in particular, in the lung studies [8] the accuracy of Raman analysis of neoplasms was only 77%. Similar trend is seen in the studies of other biological tissues, e.g., the skin.…”

Complementary analysis of tissue homogenates composition obtained by Vis and NIR laser excitations and Raman spectroscopy

“…1 and 4). This problem was also noticed in Raman studies on unfixed (air-dried) cross sections of lung tissues collected by using these laser lines [26,27]. Despite this fact bands present in all spectra provide some information about lipids and proteins.…”

“…Additionally, since Raman features depend on the wavelength of the laser excitation as well as the contribution of resonance Raman (RR) effect of chromophoric components, we recorded Raman spectra of the tissues with the use of the most common laser lines in the radiation range from 488 to 785 nm. Although most Raman studies on animal and human tissues have been mainly carried out using the NIR laser excitation (785 nm) due to the RR effect of heme-based metalloproteins and fluorescence background [3,4,6,11,12,18], some investigations have been also performed with an excitation in the Vis region of radiation [13,15,21,[26][27][28][29]. It is possible since recent technological developments allow for tight laser focusing (creating a small voxel), and consequently eliminating the contribution of fluorescent components to Raman spectrum registered from a larger volume of the laser spot [8,13,15,21].…”