Near Infrared Technology
The Infrascanner can be a practical solution to the problem of early identification of intracranial hematomas because of the unique light-absorbing properties of hemoglobin and the non-invasive, non-ionizing nature of NIR technology. The basic method for intracranial hematomas detection with Near Infrared Spectroscopy (NIRS) is based on the differential light absorption of the injured vs. the non-injured part of brain. Under normal circumstances, the brain’s absorption should be symmetrical when comparing left and right sides. Extravascular blood absorbs NIR light more than intravascular blood since there is a greater (usually 10-fold greater) concentration of hemoglobin in the acute hematoma than in the brain tissue where blood is contained within vessels. Therefore, the absorbance of NIR light is greater (and therefore the reflected light less) on the side of the brain containing a hematoma, than on the uninjured side.
The Infrascanner compares the left and right sides of the brain in four different areas. The NIRS sensor is placed successively in the left and right frontal, temporal, parietal, and occipital areas of the head and the absorbance of light at selected wavelengths is recorded.
The difference in optical density (ΔOD) in the different areas is calculated from the following formula:
Where IN = the intensity of reflected light on the normal side, IH = the intensity of reflected light on the hematoma side.