Measurement of inner ear blood flow by laser Doppler flowmetry: the optical characteristics and a flow model study of the inner ear

摘要

Abstract: Laser Doppler flowmetry has widely been used toinvestigate the real time changes of the local bloodflow in the inner ear. However the optical propertiesof the cochlea have not thoroughly been investigated.We have investigated the optical characteristics of thebony layer of the guinea pig cochlea by means of anintegrating sphere and determined the absorption andscattering coefficients. A Delrin plate withapproximately the same optical properties as the bonylayer was used as a model in some of the measurements.In a flow model the geometrical conditions of thecochlea were studied. The flow model consists of asingle capillary and the Doppler shifted signals weremeasured by a single optical fiber. Results show, thechanges of the Doppler shifted signals were related tothe distance between the photodetector and thescattering medium. From our results we can concludethat the laser Doppler measurements include informationon the blood flow in structures deeper than 1 mm belowthe bone surface (guinea pigs). !15