Evaluation of a confocal Raman probe for pathological diagnosis during colonoscopy.
OBJECTIVE
Raman spectroscopy of human tissue can provide a unique biochemical 'fingerprint' that alters with disease progression. Light incident on tissue is scattered and may be altered in wavelength, which can be represented as a Raman spectrum. A confocal fibreoptic Raman probe designed to fit down the accessory channel of a colonoscope has been constructed. This in-vitro study evaluated the accuracy of pathological diagnosis in the colon using probe-based Raman spectroscopy.


METHODS
Biopsy samples were collected at colonoscopy, snap frozen and stored at -80 °C. Raman spectra with 10-s and 1-s acquisition periods were measured with the probe tip in contact with the mucosal surface of thawed specimens. Mathematical modelling using principal component analysis followed by linear discriminant analysis was used to correlate Raman spectra with histopathological diagnoses.


RESULTS
Three-hundred and seventy-five Raman spectra were measured from a total of 356 colon biopsies (81 of normal colon mucosa, 79 of hyperplastic polyps, 92 of adenomatous polyps, 64 of adenocarcinoma and 40 of ulcerative colitis) from 177 patients. Spectral classification accuracies comparing pathology pairs ranged from 72.1 to 95.9% for 10-s acquisitions and from 61.5 to 95.1% for 1-s acquisitions. For a three-group model of normal, adenomatous and adenocarcinoma tissue, accuracies were 74.1% for 10-s acquisitions and 63.5% for 1-s acquisitions.


CONCLUSIONS
The confocal Raman probe system can distinguish between different colorectal pathologies. The probe has potential to establish Raman spectroscopy as a clinical tool for instant diagnosis at colonoscopy.
Department of Surgery, Gloucestershire Hospitals NHS Foundation Trust, Gloucester, UK; Biophotonics Research Unit, Gloucestershire Hospitals NHS Foundation Trust, Gloucester, UK.
J J
JJ
Wood
C
C
Kendall
J
J
Hutchings
G R
GR
Lloyd
N
N
Stone
N
N
Shepherd
J
J
Day
T A
TA
Cook
D000230:Adenocarcinoma / Q000473:pathology; D018256:Adenomatous Polyps / Q000473:pathology; D000368:Aged; D001706:Biopsy; D003093:Colitis, Ulcerative / Q000473:pathology; D003106:Colon / Q000473:pathology*; D003108:Colonic Diseases / Q000473:pathology*; D003111:Colonic Polyps / Q000473:pathology; D003113:Colonoscopy / Q000295:instrumentation*; D016002:Discriminant Analysis; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D007413:Intestinal Mucosa / Q000473:pathology*; D008297:Male; D018613:Microscopy, Confocal / Q000295:instrumentation*; D008875:Middle Aged; D025341:Principal Component Analysis; D013059:Spectrum Analysis, Raman / Q000295:instrumentation*
Colorectal; Raman; cancer; histology; spectroscopy