Optically Pumped Magnetometer Brain Measurement Apparatus
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Solution Overview
Problem
Integrating magnetoencephalography and MRI measurements is challenging due to the need to reduce environmental magnetic fields and generate specific magnetic fields, which existing technologies struggle to manage efficiently, leading to interference and increased costs and size of equipment.
Innovation Solution
A brain measurement apparatus and method that uses optically pumped magnetometers, static magnetic field nulling coils, and gradient magnetic field coils, controlled by a controller to cancel environmental magnetic fields and apply necessary magnetic fields for both magnetoencephalography and MRI measurements, eliminating the need for superconducting coils and magnetic shields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a magnetoencephalograph and MRI apparatus are integrated, then both brain magnetic field measurement and MRI measurement can be performed using the same system, but the environmental magnetic field reduction and static magnetic field generation become conflicting requirements that complicate the system design
Solution Approach 1:
The magnetic field management system is segmented into distinct functional modules: optically pumped magnetometers for brain magnetic field detection, static magnetic field nulling coils for environmental field cancellation, and gradient magnetic field coils for MRI spatial encoding. Each module operates independently with dedicated control, allowing the system to switch between magnetoencephalography and MRI modes without interference.
Solution Approach 2:
The system dynamically adjusts the operational state of different magnetic field components based on the measurement mode. During magnetoencephalography, the static magnetic field nulling coils are activated to cancel environmental fields while gradient coils remain inactive. During MRI, the nulling coils are deactivated and gradient coils are activated for spatial encoding, enabling flexible adaptation to different measurement requirements.
2Measurement precision
If traditional SQUID-based magnetoencephalograph is used, then brain magnetic field can be measured, but the requirement for magnetic shield rooms and liquid helium increases equipment size and cost
Solution Approach 1:
The patent replaces the SQUID-based detection system with optically pumped magnetometers that use optical pumping of alkali metal atoms to detect magnetic fields. This substitution eliminates the need for superconducting materials and liquid helium cooling systems, significantly reducing equipment size and operational complexity while maintaining high measurement precision for brain magnetic fields.
Solution Approach 2:
The system uses room-temperature operating magnetometers instead of expensive, cryogenically-cooled SQUID systems. The optically pumped magnetometers operate at ambient temperatures without requiring liquid helium, effectively replacing expensive, maintenance-intensive components with simpler, more economical alternatives that eliminate the need for magnetic shield rooms.
3Measurement precision
If static magnetic field is generated for MRI, then MRI measurement can be performed, but the static magnetic field interferes with brain magnetic field measurement by the magnetoencephalograph
Solution Approach 1:
The system extracts and separately manages the static magnetic field generation function from the MRI subsystem. The static magnetic field is generated by a dedicated permanent magnet or electromagnet that can be independently controlled and switched off when magnetoencephalography is performed. This separation allows the magnetoencephalograph to operate without interference from static magnetic fields while maintaining full MRI capability when needed.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables efficient and accurate simultaneous brain magnetic field and MRI measurements, reducing equipment size and cost, minimizing registration errors, and allowing for high-accuracy imaging without the need for liquid helium or magnetic shield rooms.
Implementation Method 1
The optically pumped magnetometer measures small magnetic field by using the spin polarization of alkali metal atoms excited by optical pumping
Implementation Method 2
control a current to be supplied to the static magnetic field nulling coil based on measured values of the multiple magnetic sensors for static magnetic field cancellation and operate so as to cancel a static geomagnetic field and a static magnetic field generated by the permanent magnet
Implementation Method 3
a permanent magnet for applying a static magnetic field
Implementation Method 4
controlling the gradient magnetic field by controlling a current to be supplied to the gradient magnetic field coil
Implementation Method 5
a transmission coil for transmitting a transmission pulse having a predetermined frequency
Implementation Method 6
a receive coil for detecting a nuclear magnetic resonance signal generated by the transmission of the transmission pulse
Data Source
AI summary
A brain measurement apparatus includes: a magnetoencephalograph including optically pumped magnetometers, magnetic sensors for measuring a static magnetic field at positions of the optically pumped magnetometers, and a nulling coil for canceling the static magnetic field; an MRI apparatus including a permanent magnet, a gradient magnetic field coil, a transmission coil, and a receive coil for detecting a nuclear magnetic resonance signal; and a control device that, when measuring the brain's magnetic field, controls a current to be supplied to the nulling coil based on measured values of the magnetic sensors and operates so as to cancel a static magnetic field at the position of each of the optically pumped magnetometers and, when measuring an MR image, controls the gradient magnetic field by controlling a current to be supplied to the gradient magnetic field coil and generates an MR image based on an output of the receive coil.