Elimination of disruptive effect of extracerebral biological tissues in near infrared spectroscopy

The non-invasive measurement of cerebral oxy-haemoglobin(HbO^br₂) and deoxy-haemoglobin (HHb^br) changes using near-infrared spectroscopy instruments is often affected by the absorption in the extracerebral layer. The changes in the extra cerebral and cerebral hemodynamics arise from different physiological facts. Therefore the changes corresponding to these hemodynamics with respect to time occur at different speeds. Based on that fact if a suitable filtering is applied it was shown that hemodynamics corresponding to brain can be obtained more accurately.