Fluorescence and Raman spectroscopy.

Table 2 provides a summary of selected in vivo fluorescence and Raman studies performed in BE. Although the findings from these studies appear promising, these techniques are still under development, and it is anticipated that technological refinements will further enhance their diagnostic accuracy. Ultimately, however, large-scale prospective clinical trials are required to determine their true diagnostic potential in BE and other sites. Ideally, the instrumentation of choice would be a real-time endoscopic system that combines excellent diagnostic accuracy with wide-area sampling. In this regard, fluorescence imaging is most appealing, although a variety of issues remain to be resolved, including the choice between autofluorescence versus drug-induced fluorescence and the problematic distinction between dysplastic (true positive) and confounding background metaplastic fluorescence (false positive), among others. It is also not clear whether exogenous fluorophores are necessary to achieve clinically useful sensitivity and specificity for lesion detection in BE. Point spectroscopic techniques, either fluorescence or Raman scattering, are inherently limited by the small volume of tissue (biopsy specimen size) they sample, but more detailed information can be extracted from the spectra, which may increase diagnostic accuracy. Moreover, it may be that the optimal system will be a combination of multiple optical spectroscopic or imaging techniques (multimodality approach), as suggested by Georgakoudi et al. For instance, a lesion could be detected by fluorescence imaging and its dysplastic nature characterized (graded) by Raman spectroscopy. In this era of cost containment, however, the critical challenge is to demonstrate whether an increase in diagnostic accuracy merits investment in costly technology, regardless of the technique used.