NIR Spectroscopy of the Brain

Over the last years, various methods have been developed to measure brain functions. In most cases the basis is a change in oxygen consumption of the tissue, followed by an increase in blood flow and a subsequent increase in blood oxygenation in conjunction with changes in the oxygenated and deoxygenated form of haemoglobin (oxyHb, deoxyHb). Near-infrared spectroscopy allows a relatively simple assessment of haemoglobin in tissue by the absorption measurement. Functional brain mapping in humans: The figure depicts a functional activation map of the cortex of an adult human volunteer after a simple finger tapping motor task (Steinbrink et al., Charité). The map is based on 45 measurement positions the time traces of which are shown on the left. A region with large changes in oxyHb (red) and deoxyHb (blue) is discernable which appears in the false colour map on the right.

Monitoring of cerebral oxygenation during cardio-surgery in infants:

Currently, there is no routine method available to monitor the brain oxygen conditions during heart surgery. NIRS monitoring offers a non-invasive tool for this purpose. The figure shows cerebral oxygen saturation measured with our broadband spatially-resolved system during open heart surgery of an infant. There are large swings in the oxygen conditions during all phases of the surgery. Prominent changes are when the cario-pulmonary bybass is changed and the blood supply to the brain stopped.