Abstract:
The utilisation of near-infraredR aman spectroscopyfo r the discrimination of cancersa nd
pre-cancers from normal tissue in the acro-digestive tract has been evaluated. A
commercially available Raman microspectrometehr as been modified to provide optimum
throughput, sensitivity and fluorescence suppression for epithelial tissue measurements.
Laser excitation at 830nmw as demonstratedto be optimum. High quality (SN ratio 15-20)
NIR-Raman spectrah ave been acquired from oesophageaal nd laryngeal tissues in time
scales under 30 seconds.
Pathological groupings covering the full range of normal and neoplastic tissues in the organs
of interest have been studied. Both fresh (snap frozen) and formalin fixed tissue samples
were investigated,f irstly to indicate whether tissue-typesc an be distinguishedi n vivo and
secondlyt o demonstrateth e use of Raman spectroscopya s a tool for classificationi n the
pathology lab.
Results using multivariate statistical techniques to distinguish between spectra from
specimens exhibiting different tissue pathologies have been extremely promising. Crossvalidation
of the spectral predictive models has shown that three groups of larynx tissue
can be separated with sensitivities and specificities of between 86 and 90% and 87 and
95% respectively. Oesophageal prediction models have demonstrated sensitivities and
specificities of 84 to 97% and 93 to 98% respectively for a three-group consensus model
and 73 to 100% and 92 to 100% for an eight-groupc onsensusm odel.
Epithelial tissues including stomach, tonsil, endometrium, bladder and prostate have been
studiedt o identify further tissuesw hereR amans pectroscopym ay be employedf or detection
of disease.S pectraw ere similar to those obtainedf rom oesophagusa nd larynx, although
sufficiently different for distinct discriminant models to be required. This work has
demonstratedth e genericn atureo f Ramans pectroscopyfo r the detectiona nd classification
of cancersa nd pre-cancerousle sionsi n many tissues.T he evidencep rovided by this study
indicatest hat utilisation of Ramans pectroscopyfo r non-invasived etectiona nd classification
of diseaseis a distinct possibility. Potentiald ifficulties in the transferabilityf rom in vitro to
in vivo have been evaluated and no significant barriers have been observed. However,
further in vivo probe development and optimisation will be required before 'optical biopsy'
with Ramans pectroscopyc anb ecomea reality.
