A Superconducting Quantum Interference Device Detection Coil Design with Enhanced Sensitivity for Deep Brain Activation

概要

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We propose a new combination coil system to be used in magnetoencephalography (MEG). This system is capable of detecting magnetic signals produced by brain activation located in deep regions (40 mm to 60 mm beneath the head skin) while minimizing brain noises that arise from shallow regions (10 mm to 30 mm beneath the head skin). The system has two coils at each measurement location around the head, a magnetometer coil and a second-order gradiometer coil, which have different dependences of magnetic sensitivity to the distance between the coils and brain activation sources. The magnetic signals detected by one coil multiplied by a weighting coefficient is subtracted from those detected by the other coil so that the magnetic sensitivity for the combination coil is more enhanced for deep sources than for shallow ones. We designed a practical configuration of the combination coil system by optimizing the weight and the base line length of the gradiometer. We improved the signal-to-noise ratio for typical source and noise depths by sixteen times in comparison with a conventional magnetometer coil. By optimizing parameters, we obtained magnetic sensitivity that was 3.6 times higher on average for deep brain signal sources than for shallow brain noise sources.
Published by the Japan Society of Applied Physics through the Institute of Pure and Applied Physicsの論文
2004-08-15