NIR Spectroscopy of the Brain

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.

Functional cortical activation in babies:

More recently we started to apply near-infrared spectroscopy for the monitoring of functional activation in the infant brain. NIR spectroscopy is well suited for this application as other modalities like MRI are ruled out as movement artefacts are likely.

Cortical functional activation during sports:

In an ongoing study together with exercise physiologists we investigate the link of muscle and cortical activation.

All this work is based on our instrument development and the tissue spectroscopy algorithms, where already some other examples were discussed.