Cost-Effective Magnetoencephalography Based on Time-Encoded Optical Fiber Interferometry for Epilepsy and Tinnitus Diagnosis
Abstract
Topic Areas: Epilepsy and Tinnitus Epilepsy and tinnitus originate from functional brain disorders. Anatomical imaging tools like MRI (magnetic resonance imaging) and CT (computed tomography) could be "blind" to these disorders. In contrast, magnetoencephalography (MEG) monitors brain activities in real time and is very effective at studying, screening, and diagnosing epilepsy and tinnitus, providing insightful information for surgical treatments. Unfortunately, there are less than two dozen MEG machines in the United States due to the high acquisition ($3 million) and operational ($200,000 per year) costs. Existing MEG technique uses hundreds of low temperature superconducting magnetic sensors placed around a patient s head and are cooled by expensive liquid Helium. Patients can t freely move during diagnosis. This not only drives up the cost but also makes deployment of MEG to field hospitals and battleships impossible. The ultimate goal of this research is to develop a cost-effective and compact MEG method that can be made widely available for studying and diagnosing epilepsy and tinnitus, even in mobile hospitals. Our idea is to perform MEG using a single fiber optical device operating at non-cryogenic temperature. The above MEG method is based on two major innovations, which will be experimentally tested in this project. The first is the use of a sensitive fiber optical technique called Sagnac interferometer to perform magnetic field sensing. The Sagnac interferometer is being used as the most accurate gyroscopes in planes and rockets. Applying this optical technique to MEG would potential lead to at least 10 times better sensitivity than superconducting sensors. The second is the use of a single fiber to simultaneously record the magnetic field distribution around a patient s head. This is analogous to transmitting videos along a single fiber-optical network cable, where the color information at different positions is encoded (stored) as a time-trace of light. In the proposed approach, different colors of light from a single fiber will be projected onto different locations around a patient s head. The end of the fiber interferometer is so designed that different colors of light travel at slightly different speeds. A computer will "decode" the information and generate 3D brain activity image, similar to a television converter box, which "decodes" cable signal into TV videos. Success of this project would make possible a revolutionary MEG technique where the performance is enhanced 10-fold and the cost is reduced 30 times. This would make a qualitative change to the availabilities of MEG. It also has other virtues including compact size (size of a football helmet), high speed (up to 1 million images per second), and the patient can move freely as he/she is linked through a single fiber to MEG instrument. The compact size opens up the possibility of deploying MEG to field hospitals and battleships where servicemen who have been subject to TBI (traumatic brain injury) and extreme noise could be screened for functional brain disorders before epilepsy and tinnitus fully develop. It is possible to envision future high speed MEG studies of epilepsy and tinnitus in environments simulating that of battlefield where patients can move freely. This will help to find ways to prevent epilepsy and tinnitus in servicemen and veterans.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Apr 04, 2016
- Source ID
- W81XWH1510008
Entities
People
- Jing Xia
Organizations
- Naval Information Warfare Center Pacific
- United States Army