title: In vivo endoscopic tissue diagnostics based on spectroscopic absorption, scattering, and phase function properties.
abstract: A fast spectroscopic system for superficial and local determination of the absorption and scattering properties of tissue (480 to 950 nm) is described. The probe can be used in the working channel of an endoscope. The scattering properties include the reduced scattering coefficient and a parameter of the phase function called gamma, which depends on its first two moments. The inverse problem algorithm is based on the fit of absolute reflectance measurements to cubic B-spline functions derived from the interpolation of a set of Monte Carlo simulations. The algorithm's robustness was tested with simulations altered with various amounts of noise. The method was also assessed on tissue phantoms of known optical properties. Finally, clinical measurements performed endoscopically in vivo in the stomach of human subjects are presented. The absorption and scattering properties were found to be significantly different in the antrum and in the fundus and are correlated with histopathologic observations. The method and the instrument show promise for noninvasive tissue diagnostics of various epithelia.
authors.affiliation: Swiss Federal Institute of Technology, Applied Optics Institute, PO Box 127, CH-1015 Lausanne, Switzerland. philippe.thueler@bigfoot.com
authors.forename: Philippe
authors.initials: P
authors.lastname: Thueler
authors.forename: Igor
authors.initials: I
authors.lastname: Charvet
authors.forename: Frederic
authors.initials: F
authors.lastname: Bevilacqua
authors.forename: M
authors.initials: M
authors.lastname: St  Ghislain
authors.forename: G
authors.initials: G
authors.lastname: Ory
authors.forename: Pierre
authors.initials: P
authors.lastname: Marquet
authors.forename: Paolo
authors.initials: P
authors.lastname: Meda
authors.forename: Ben
authors.initials: B
authors.lastname: Vermeulen
authors.forename: Christian
authors.initials: C
authors.lastname: Depeursinge
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D001706:Biopsy / Q000379:methods; D003936:Diagnosis, Computer-Assisted / Q000379:methods*; D020776:Endoscopes, Gastrointestinal; D004724:Endoscopy / Q000379:methods; D016099:Endoscopy, Gastrointestinal / Q000379:methods*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D019047:Phantoms, Imaging; D015203:Reproducibility of Results; D012542:Scattering, Radiation; D012680:Sensitivity and Specificity; D013057:Spectrum Analysis / Q000295:instrumentation* / Q000379:methods*; D013270:Stomach / Q000166:cytology*