Optical tomography of the neonatal brain

Abstract

A new method of assessing neurological function and pathology in the newborn infant is being developed based on the transmission of near-infrared light across the brain. Absorption by blood over a range of wavelengths reveals a strong dependency on oxygenation status, and measurements of transmitted light enable the spatial variation in the concentrations of the oxygenated and de-oxygenated forms of hemoglobin to be derived. Optical tomography has so far provided static three-dimensional maps of blood volume and oxygenation as well as dynamic images revealing the brain's response to sensory stimulation and global hemodynamic changes. The imaging modality is being developed as a safe and non-invasive tool that can be utilized at the cotside in intensive care. Optical tomography of the healthy infant brain is also providing a means of studying neurophysiological processes during early development and the potential consequences of prematurity.

Non-invasive optical imaging of stroke

“…While subdural, epidural, traumatic and atypical lobar haemorrhage affect parts of the brain that can be interrogated by OI, their presentation, risk factors or relative rarity may not justify advocating OI as a relevant tool for the differential diagnosis between ischaemic and haemorrhagic strokes [17][18][19]. The potential of the methodology with regard to the detection of a haemorrhage may thus be limited to infants and (premature) neonates, in whom tomographic approaches have yielded promising results [20][21][22].…”

Near infrared spectroscopy to study the brain: an overview

“…The measured data is spatially reconstructed to obtain images of absorption and scattering. 2D (here called NIRI or optical imaging, also called optical topography or diffuse optical imaging) and 3D (optical tomography) images can thus be obtained (overview of the technical approaches in adults and neonates [13,14], summaries of functional imaging studies in adults [15][16][17][18][19][20]). Optical imaging is used by an increasing number of research groups [13].…”

“…Time domain optical tomography was applied to study the head of neonates [13,14,25]. 3D optical tomography still has a low spatial resolution of 1 to 2 cm and requires 10 min of time to acquire an image [13] and was despite this limit recently used for a functional study [14,26].…”

“…There are few reports in the literature on hemodynamic effects in neonates, visual cortex [66][67][68], auditory cortex [69][70][71][72], speech frontal cortex [73], olfactory stimulation [74,75], pain [76][77][78], and motor cortex [14]. Bartocci's [75] findings during the presentation of unpleasant smells to infants are highly particular, because a decrease in O 2 Hb concentration was observed, while the HHb concentration remained approximately constant.…”

“…Optical imaging techniques in neonates clearly demonstrate a diagnostic potential [68,69,72,[80][81][82][83], while optical tomography [14], although promising and fascinating, still needs development.…”