Portable Near Infrared Technology for Detection of Traumatic Brain Injuries in Operational Environments

Acute head trauma can cause disability and death without prompt diagnosis and treatment. The methods of choice for such diagnosis are x-ray CT or MRI, but these systems are costly and lack portability. Blood has an electrical conductivity and a dielectric permittivity about 50 to 100% higher than that of healthy brain tissue, depending on the excitation frequency. This suggests that an entirely non-contact technique for detecting bleeding in the brain (hematoma) could be based on a magnetic induction measurement that responds to anomalous changes in the conductivity between the skull and dura. One possible design of such a sensor would consist of concentric transmitting and receiving coils in close proximity to the head, but not touching. If the frequency is swept over a suitable range, then a one-dimensional profile of conductivity as a function of depth could be generated by exploiting the electromagnetic skin effect. The advantages of this approach over near-infrared spectroscopy include the non-contact nature of the measurement and the possibility of using a conductivity profile to delineate the dimensions of the hematoma. A conductivity sensor could be designed to be portable, compact and relatively inexpensive. A prototype sensor suitable for testing on tissue phantoms will be developed in Phase I.