Effects of skin on bias and reproducibility of near-infrared spectroscopy measurement of cerebral oxygenation changes in porcine brain.

Radboud University Nijmegen Medical Centre, Department of Pediatrics, Clinical Physics, Nijmegen, The Netherlands.
Journal of Biomedical Optics (Impact Factor: 2.75). 01/2005; 10(4):44003. DOI: 10.1117/1.1989315
Source: PubMed

ABSTRACT The influence of skin on the bias and reproducibility of regional cerebral oxygenation measurements is investigated using cw near-infrared spectroscopy (NIRS). Receiving optodes are placed over the left and right hemispheres of a piglet (C3, C4 EEG placement code) and one transmitting optode centrally (Cz position). Optical densities (OD) are measured during stable normo, mild, and deep hypoxemia. This is done for skin condition 1: all optodes on the skin; skin condition 2: transmitting optode on the skin and one receiving optode on the skull; and skin condition 3: all optodes on the skull. Absolute changes of oxy- (cO2Hb), deoxyhemoglobin (cHHb), and total hemoglobin (ctHb) concentrations [micromolL] are calculated from the ODs. These absolute changes are calculated for each skin condition with respect to normoxic condition. Additionally, for skin condition 2, the difference of concentration changes between receiver 1 (skull) and receiver 2 (skin) is calculated. The effect of skin removal is an average increase of attenuation changes by a factor of 1.66 (=0.51 OD) and of the concentration changes due to the arterial oxygen saturation steps by 23%. We conclude that skin significantly influences regional oxygenation measurements. Nevertheless, it is hypothesized that the estimated concentration changes are dominated by changes of the oxygenation in the brain.

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    • "As the regions immediately beneath optodes have extremely high sensitivity, blood circulation change beneath or near an optode strongly degrades the reliability of the topograph. NIRS devices cannot distinguish blood circulation change of the cerebral cortex from that of skin with autonomic nerve activity (Klaessens et al., 2005; Scott L. Davis, 2006). Numerous studies have been conducted in the field of 3D diffuse optical tomography (DOT) in order to realize quantitative and accurate imaging of heterogeneity in tissue, through the use of intensive systems such as time-domain or frequency-domain system (Schweiger et al., 1993; O'Leary et al., 1995; Arridge and Schweiger, 1997; Boas et al., 2001; Gao et al., 2002; Kilmer et al., 2003; Stott et al., 2003; Graber et al., 2007; Kim et al., 2008). "
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