Breast Tumor Analysis Using Shifted-Excitation Raman Difference Spectroscopy (SERDS)

Abstract

We used a shifted-excitation Raman difference spectroscopy method for the ex vivo classification of resected and formalin-fixed breast tissue samples as normal (healthy) tissue, fibroadenoma, or invasive carcinoma. We analyzed 8 tissue samples containing invasive carcinoma that were surrounded by normal tissue and 3 tissue samples with fibroadenoma only. We made various measurement sites on various tissue samples, in total 240 measurements for each type of tissue. Although the acquired raw spectra contain enough information to clearly differentiate between normal and tumor (fibroadenoma and invasive carcinoma) tissue, the differentiation between fibroadenoma and invasive carcinoma was possible only after the shifted-excitation Raman difference spectroscopy isolation of pure Raman spectra from the heavily fluorescence interfered raw spectra. We used 784 and 785 nm as excitation wavelengths for the shifted-excitation Raman difference spectroscopy method. The differences in the obtained pure Raman spectra are assigned to the different chemical compositions of normal breast tissue, fibroadenoma, and invasive breast carcinoma. Principal component analysis and linear discriminant analysis showed excellent classification results in the Raman shift range between 1000 and 1800 cm−1. Invasive breast carcinoma was identified with 99.15% sensitivity, and the absence of invasive carcinoma was identified with 90.40% specificity. Tumor tissue in tumor-containing tissue was identified with 100% sensitivity, and the absence of tumor in no-tumor containing tissue was identified with 100% specificity. As gold standard for the determination of the sensitivity and the specificity, we considered the conventional histopathological classification. In summary, shifted-excitation Raman difference spectroscopy could be potentially very useful to support histopathological diagnosis in breast pathology.

Evaluation of aromatic amino acids as potential biomarkers in breast cancer by Raman spectroscopy analysis

“…5. While the statistical analysis of the contributions of both healthy and cancerous cells becomes less accurate as the total number of data points decrease at higher relative intensity thresholds, it nevertheless, indicates that the characteristic Raman bands of aromatic amino acids in cancerous cells exhibit higher intensities and hence, they are present in higher concentrations 33,43,45 . This conclusion is in accordance with various observations regarding the enhanced prevalence of aromatic amino acids in cancerous tissues.…”

Refinement of spectra using a deep neural network: Fully automated removal of noise and background

“…Raman spectroscopy is a species‐specific and quantitative measurement technique. [ 1 ] Due to its high sensitivity to subtle chemical and biochemical changes and amenability to noninvasive applications, this technique has been widely applied in numerous fields, such as chemical processing, [ 2–4 ] biomedical diagnostics, [ 5–7 ] arts and archeology, [ 8,9 ] and others.…”

Sub millimetre flexible fibre probe for background and fluorescence free Raman spectroscopy

“…One such challenge is the silica background generated from the optical fibres used to remotely examine otherwise unreachable tissue regions [2]. Another significant drawback is the autofluorescence background generated from these tissue regions [3]. When examining biomedical samples, the characterisation relies on identifying small and subtle variations in the Raman spectrum.…”

“…Computational (numerical or software based methods), for example, polynomial fitting [10] or extended multiplicative scatter correction (EMSC) [11], utilise known or expected properties of the signals (eg the shape of fluorescence background) and statistical models to suppress the fluorescence content in the recorded data and to separate the Raman signal. Techniques such as shifted-excitation Raman difference spectroscopy (SERDS) [3,[12][13][14] and wavelength modulated Raman spectroscopy (WMRS) [15] can be considered as the combination of the two. SERDS utilises the fact that the fluorescence background is unaffected by a small shift in the wavelength of the incident laser light.…”