title: Optical properties of rabbit brain in the red and near-infrared: changes observed under in vivo, postmortem, frozen, and formalin-fixated conditions.
abstract: The outcome of light-based therapeutic approaches depends on light propagation in biological tissues, which is governed by their optical properties. The objective of this study was to quantify optical properties of brain tissue in vivo and postmortem and assess changes due to tissue handling postmortem. The study was carried out on eight female New Zealand white rabbits. The local fluence rate was measured in the VIS/NIR range in the brain in vivo, just postmortem, and after six weeks’ storage of the head at −20°C or in 10% formaldehyde solution. Only minimal changes in the effective attenuation coefficient μeff were observed for two methods of sacrifice, exsanguination or injection of KCl. Under all tissue conditions, μeff decreased with increasing wavelengths. After long-term storage for six weeks at −20°C, μeff decreased, on average, by 15 to 25% at all wavelengths, while it increased by 5 to 15% at all wavelengths after storage in formaldehyde. We demonstrated that μeff was not very sensitive to the method of animal sacrifice, that tissue freezing significantly altered tissue optical properties, and that formalin fixation might affect the tissue’s optical properties.)
authors.affiliation: Swiss Federal Institute of Technology, Institute of Chemical Sciences and Engineering, Station 6, Lausanne CH-1015, Switzerland.
authors.forename: Andreas
authors.initials: A
authors.lastname: Pitzschke
authors.affiliation: Swiss Federal Institute of Technology, Institute of Chemical Sciences and Engineering, Station 6, Lausanne CH-1015, SwitzerlandbMedos International Sàrl, a J&J Company, Chemin Blanc 38, Le Locle CH-2400, Switzerland.
authors.forename: Blaise
authors.initials: B
authors.lastname: Lovisa
authors.affiliation: Swiss Federal Institute of Technology, Institute of Chemical Sciences and Engineering, Station 6, Lausanne CH-1015, Switzerland.
authors.forename: Olivier
authors.initials: O
authors.lastname: Seydoux
authors.affiliation: University of Bern, Department of Neurosurgery, Bern University Hospital, Inselspital, Bern CH-3010, Switzerland.
authors.forename: Matthias
authors.initials: M
authors.lastname: Haenggi
authors.affiliation: University of Bern, Department of Intensive Care Medicine, Bern University Hospital, Inselspital, Bern CH-3010, Switzerland.
authors.forename: Markus F
authors.initials: MF
authors.lastname: Oertel
authors.affiliation: Swiss Federal Institute of Technology, Institute of Chemical Sciences and Engineering, Station 6, Lausanne CH-1015, Switzerland.
authors.forename: Matthieu
authors.initials: M
authors.lastname: Zellweger
authors.affiliation: Medos International Sàrl, a J&J Company, Chemin Blanc 38, Le Locle CH-2400, Switzerland.
authors.forename: Yanik
authors.initials: Y
authors.lastname: Tardy
authors.affiliation: Swiss Federal Institute of Technology, Institute of Chemical Sciences and Engineering, Station 6, Lausanne CH-1015, Switzerland.
authors.forename: Georges
authors.initials: G
authors.lastname: Wagnières
mesh_terms: D000818:Animals; D001344:Autopsy; D001921:Brain / Q000187:drug effects / Q000502:physiology*; D001923:Brain Chemistry / Q000502:physiology*; D003080:Cold Temperature; D005260:Female; D005557:Formaldehyde / Q000494:pharmacology; D011817:Rabbits; D019265:Spectroscopy, Near-Infrared; D016707:Tissue Fixation / Q000379:methods*
chemical_list: D005557:Formaldehyde