Characterizing variability in in vivo Raman spectra of different anatomical locations in the upper gastrointestinal tract toward cancer detection

Abstract

Abstract. Raman spectroscopy is an optical vibrational technology capable of probing biomolecular changes of tissue associated with cancer transformation. This study aimed to characterize in vivo Raman spectroscopic properties of tissues belonging to different anatomical regions in the upper gastrointestinal (GI) tract and explore the implications for early detection of neoplastic lesions during clinical gastroscopy. A novel fiber-optic Raman endoscopy technique was utilized for real-time in vivo tissue Raman measurements of normal esophageal (distal, middle, and proximal), gastric (antrum, body, and cardia) as well as cancerous esophagous and gastric tissues from 107 patients who underwent endoscopic examinations. The non-negativity-constrained least squares minimization coupled with a reference database of Raman active biochemicals (i.e., actin, histones, collagen, DNA, and triolein) was employed for semiquantitative biomolecular modeling of tissue constituents in the upper GI. A total of 1189 in vivo Raman spectra were acquired from different locations in the upper GI. The Raman spectra among the distal, middle, and proximal sites of the esophagus showed no significant interanatomical variability. The interanatomical variability of Raman spectra among normal gastric tissue (antrum, body, and cardia) was subtle compared to cancerous tissue transformation, whereas biomolecular modeling revealed significant differences between the two organs, particularly in the gastroesophageal junction associated with proteins, DNA, and lipids. Cancerous tissues can be identified across interanatomical regions with accuracies of 89.3% [sensitivity of 92.6% (162/175); specificity of 88.6% (665/751)], and of 94.7% [sensitivity of 90.9% (30/33); specificity of 93.9% (216/230)] in the gastric and esophagus, respectively, using partial least squares-discriminant analysis together with the leave-one tissue site-out, cross validation. This work demonstrates that Raman endoscopy technique has promising clinical potential for real-time, in vivo diagnosis and detection of malignancies in the upper GI at the molecular level. C 2011 Society of Photo-Optical Instrumentation Engineers (SPIE).

Raman active components of skin cancer

“…Some were commonly used in skin and non-skin models. For instance, collagen and triolein are known to be important contributors to the RS signal of breast, gastric, and artery tissues [17,19,20]. We demonstrated these two components also played an important role for fitting in vivo skin data.…”

“…The building blocks of our model are Raman active components extracted from skin in situ. Previous biophysical models used model components either measured directly from synthetic/purified chemicals [9,[15][16][17][18], or extracted from tissue sections in situ [19][20][21]. The advantage of using synthetic/purified chemicals as model components is that they can be easily measured without the need for Raman micro-imaging.…”

Classification of inflammatory bowel diseases by means of Raman spectroscopic imaging of epithelium cells

“…11,12 Also, in vivo Raman applications to achieve better diagnostic results for dysplastic diseases have been reported. 13 In contrast, little has been reported about using Raman spectroscopy to detect molecular changes taking place in epithelial cells during inflammatory conditions. A recently published study from Bi et al 14 demonstrated for the first time the potential of Raman spectroscopy (in particular fiber-optic Raman spectroscopy) in IBD by showing that Raman band heights differ for UC and CD.…”

Dispersion-based stimulated Raman scattering spectroscopy, holography, and optical coherence tomography

“…Vibrational spectroscopy provides the means to non-destructively assess the molecular composition of subcellular structures [1][2][3], trace metabolic and functional processes [4,5], and identify disease [6][7][8]. A variety of different methods have been demonstrated for extracting the molecular information, each with different characteristics (see Ref [9] for a recent review).…”