The exact volume of brain tissue interrogated in near-infrared spectroscopy (NIRS) studies of cerebral oxygenation in unknown, the inhomogeneity of the head and resulting variation in optical paths making determination of the interrogated volume difficult. In this study, the spatial sensitivity profiles in simple two-component inhomogeneous cylindrical models are predicted by Monte Carlo simula...

In order to better understand the intricacies of cerebral hemodynamics and the mechanisms behind neurovascular coupling, one must begin by understanding the many functions of blood and the circulatory system in large multicellular organisms such as ourselves. Therefore Chapter 3 begins by discussing basic mammalian physiology, with an emphasis on the vascular system. Blood rheology, vascular hy...

Glassy test strips partially coated with PVC-film including O-donor macrocyclic receptors (L), tetrabromophenolphthalein ethyl ester (TBPE(-)), and a plasticizer sensed Pb(2+) in aqueous solutions by a unique color change. Yellow films successively changed color to green, dark-blue and purple with increases of the Pb(2+) concentration. In contrast with the ordinary "optode", a characteristic ab...

Diffuse optical tomography (DOT) has recently proved useful for detecting whole-brain oxygenation changes in preterm and term newborns' brains. The data recording phase in prior explorations was limited up to a maximum of a couple of hours, a time dictated by the need to minimize skin damage caused by the protracted contact with optode holders and interference with concomitant clinical/nursing ...

Near-infrared spectroscopy (NIRS) can be used to noninvasively measure changes in the concentrations of oxy- and deoxyhemoglobin in tissue. We have previously shown that while global changes can be reliably measured, focal changes can produce erroneous estimates of concentration changes (NeuroImage 13 (2001), 76). Here, we describe four separate sources for systematic error in the calculation o...

Pulse oximetry (oxygen saturation monitoring) has markedly improved medical care in many fields, including anesthesiology, intensive care, and newborn intensive care. In obstetrics, fetal heart rate monitoring remains the standard for intrapartum assessment of fetal well being. Fetal oxygen saturation monitoring is a new technique currently under development. It is potentially superior to elect...

The influence of sediment oxygen heterogeneity, due to bioturbation, on diffusive oxygen flux was investigated. Laboratory experiments were carried out with 3 macrobenthic species presenting different bioturbation behaviour patterns: the polychaetes Nereis diversicolor and Nereis virens, both constructing ventilated galleries in the sediment column, and the gastropod Cyclope neritea, a burrowin...

Correlation analysis of low-frequency fluctuations in blood-oxygen level dependent (BOLD) fMRI data is known to yield functional connectivity maps. The procedure, also referred to as ‘resting-state connectivity’, does not rely on a specific task performance and has recently been successfully applied to optical tomography (OT) data [1]. One of the limitations of OT is the low spatial resolution....