Spectroscopic Applications in Gastrointestinal Endoscopy

Abstract

One of the major frontiers in biomedical optics has been as an adjunct to gastrointestinal endoscopy. In particular, spectroscopy of elastic light scattering has the potential of addressing many of the vexing challenges confronting endoscopists. This review discusses the principles of spectroscopy and critically evaluates performance in clinically significant scenarios. One of the best established applications is optical biopsy (in situ histological determination), and a number of techniques such as elastic scattering spectroscopy have demonstrated the ability to discriminate between neoplastic and non-neoplastic polyps. For flat dysplasia detection in Barrett's esophagus, some of the most promising spectroscopic technologies are angle-resolved low-coherence interferometry and endoscopic polarized scanning spectroscopy (the next generation light scattering spectroscopy). A new and exciting biological approach involves optical detection of field carcinogenesis. This can be exploited to reduce colonoscopic adenoma miss rate by assessing microcirculatory augmentation in the mucosa in the vicinity of the polyp using polarizationgatedspectroscopy. Furthermore, there are nano/micro-architectural correlates with diffuse field carcinogenesis throughout the colon. Indeed, technologies such as low coherence enhanced backscattering spectroscopy and partial wave spectroscopic microscopy have demonstrated that the detection of the nano-architectural alterations in the rectal mucosa can accurately sense advanced adenomas elsewhere in the colon. This may lend itself to a minimally intrusive risk stratification to identify patients who are most likely to harbor neoplasia and thus benefit from colonoscopy. Bridging these advances into the endoscopy suite requires pragmatic future development. Future studies need to focus on efficacy, cost, practicality (time required, etc), and particularly developing the paradigms that will impact upon clinical decision making. KeywordsSpectroscopy; Endoscopy; Cancer Screening; Biophotonics; Field Carcinogenesis Recently, a number of reports have heralded endoscopic triumphs in the cancer prevention arena. For instance, colonoscopic polypectomy resulted in an approximately 50% reduction in mortality from colorectal cancer (CRC). 1 With regard to Barrett's, radiofrequency ablation showed a remarkable approximately 90% decrease in esophageal adenocarcinoma development in patients harboring high-grade dysplasia. 2 However, there is considerable work remaining as highlighted by the continued toll of CRC (second leading cause of cancer

The Global Relationship between Chromatin Physical Topology, Fractal Structure, and Gene Expression

“…While histological identification of physical alterations in tumor cells shows evidence of micron-scale transformation in topology, the question naturally arises if this transformation extends to the earliest stages of tumor formation at the nanoscale. Previous studies using TEM and PWS have shown nanoscopic physical transformation in chromatin organization at these earliest stages even in histologically normal tissue181921223536. Quantitatively, chromatin structure has been shown to behave as a fractal medium at length-scales below that of chromatin loops and the upper length scale of a chromatin globule (~250 nm).…”

Autofluorescence spectroscopy and imaging: a tool for biomedical research and diagnosis

“…However, distinct and well defined emission bands beyond 600 nm can be detected, that can be ascribed to porphyrins and their derivatives. 14 7…”

Raman Spectroscopy in the Diagnosis of Ulcerative Colitis

“…[9][10][11] There are no "gold standard" tests or examinations for the diagnosis, prognosis, assessment of disease severity, or evaluation of the effects of therapy. [12][13][14][15][16] Our data suggest that Raman spectroscopy will be able to play an adjunctive or primary role in all of these areas and can be reliably used for diagnosis of UC.…”