title: Hemoglobin parameters from diffuse reflectance data.
abstract: Tissue vasculature is altered when cancer develops. Consequently, noninvasive methods of monitoring blood vessel size, density, and oxygenation would be valuable. Simple spectroscopy employing fiber optic probes to measure backscattering can potentially determine hemoglobin parameters. However, heterogeneity of blood distribution, the dependence of the tissue-volume-sampled on scattering and absorption, and the potential compression of tissue all hinder the accurate determination of hemoglobin parameters. We address each of these issues. A simple derivation of a correction factor for the absorption coefficient, μa, is presented. This correction factor depends not only on the vessel size, as others have shown, but also on the density of blood vessels. Monte Carlo simulations were used to determine the dependence of an effective pathlength of light through tissue which is parameterized as a ninth-order polynomial function of μa. The hemoglobin bands of backscattering spectra of cervical tissue are fit using these expressions to obtain effective blood vessel size and density, tissue hemoglobin concentration, and oxygenation. Hemoglobin concentration and vessel density were found to depend on the pressure applied during in vivo acquisition of the spectra. It is also shown that determined vessel size depends on the blood hemoglobin concentration used.
authors.affiliation: Bioscience Division, Los Alamos National Laboratory, Los Alamos, P.O. Box 1663, MS M888, New Mexico 87544.
authors.forename: Judith R
authors.initials: JR
authors.lastname: Mourant
authors.affiliation: Bioscience Division, Los Alamos National Laboratory, Los Alamos, P.O. Box 1663, MS M888, New Mexico 87544.
authors.forename: Oana C
authors.initials: OC
authors.lastname: Marina
authors.affiliation: Jack D. Weiler Hospital, 1825 Eastchester Road, Room 3-37, Bronx, New York 10461.
authors.forename: Tiffany M
authors.initials: TM
authors.lastname: Hebert
authors.affiliation: Einstein Cancer Center, Department of Obstetrics and Gynecology and Women's Health, 1695 Eastchester Road, Bronx, New York 10461.
authors.forename: Gurpreet
authors.initials: G
authors.lastname: Kaur
authors.affiliation: Einstein Cancer Center, Department of Obstetrics and Gynecology and Women's Health, 1695 Eastchester Road, Bronx, New York 10461.
authors.forename: Harriet O
authors.initials: HO
authors.lastname: Smith
mesh_terms: D001808:Blood Vessels / Q000033:anatomy & histology / Q000502:physiology; D002584:Cervix Uteri / Q000098:blood supply / Q000503:physiopathology; D003198:Computer Simulation; D005260:Female; D005336:Fiber Optic Technology; D006454:Hemoglobins / Q000737:chemistry*; D006801:Humans; D008955:Models, Cardiovascular; D009010:Monte Carlo Method; D009369:Neoplasms / Q000503:physiopathology; D012815:Signal Processing, Computer-Assisted; D013057:Spectrum Analysis / Q000379:methods*
chemical_list: D006454:Hemoglobins