A 30-Channel SQUID Vector Biomagnetometer System Optimized for Reclining Subjects

Adachi, Yoshiaki; Kawai, Jun; Miyamoto, Masatoshi; Kawabata, Shigenori; Okubo, Hiroshi; Fukuoka, Yuko; Komori, Hiromichi; Uehara, Gen

doi:10.1109/tasc.2005.849996

Cited by 6 publications

(4 citation statements)

References 8 publications

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“…The 30-ch SQUID system used for the human cervical SCEF measurement had the narrow observation area of 20 mm 90 mm [11], [12]. This observation area was sufficient to estimate the local conduction velocity when the stimulation was given directly to the spinal cord itself.…”

Section: Introductionmentioning

confidence: 99%

“…However, when the stimulation was given to the brachial peripheral nerves, the transition of the magnetic field distribution at the cervix was much more complicated than the simple quadrupolelike pattern. The observation area of the 30-ch SQUID system was too narrow to identify a specific transition pattern [12]. Therefore, the sensor array had to be spatially scanned to expand the observation area when we examined the peripheral nerve stimulation.…”

Section: Introductionmentioning

confidence: 99%

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A 75-ch SQUID Biomagnetometer System for Human Cervical Spinal Cord Evoked Field

Adachi

Kawai

Uehara

et al. 2007

IEEE Trans. Appl. Supercond.

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A 75-ch SQUID biomagnetometer system for the measurement of the cervical spinal cord evoked magnetic field (SCEF) was developed for the purpose of the noninvasive functional diagnosis of the spinal cord. The sensor array has 25 SQUID vector sensors arranged along the cylindrical surface to fit to the shape of the subject's neck. The magnetic fields, not only in the direction radial to the subject's body surface but also in the tangential direction, are observed in the area of 80 mm 90 mm at one time. The dewar has a unique shape with a cylindrical main body and a protrusion from its side surface. The sensor array is installed in the protruded part. This design is optimized to detect magnetic signals at the back of the neck of the subject sitting in a reclining position. We applied the developed SQUID system to the cervical SCEF measurement of normal subjects who were given electric pulse stimulation to their median nerves at the wrists. The evoked magnetic signals were successfully detected at the cervixes of all subjects. A characteristic pattern of transition of the SCEF distribution was observed as a reproducible result and the signal components propagating along the spinal cord were found in the time varying SCEF distribution. We expect that the investigation of the propagating signal components would help to establish a noninvasive functional diagnosis of the spinal cord.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A 75-ch SQUID Biomagnetometer System for Human Cervical Spinal Cord Evoked Field

Adachi

Kawai

Uehara

et al. 2007

IEEE Trans. Appl. Supercond.

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“…Figure 1 depicts the chronicle of the SQUID systems for our research of magnetoneurography. Our research and development project for magnetoneurography initiated in 1999 with technology verification through animal experiments detecting cervical spinal cord evoked field signals from cats using a 3-ch vector-type SQUID system ( 12 ), and success was achieved in 2004 in detecting spinal cord evoked magnetic field signals traveling along the cervical spinal cord of humans for the first time using a 30-ch SQUID measurement system adapted for seated subjects ( 13 ). In 2007, a measurement system known as the “supine model” was developed to detect spinal cord evoked magnetic fields from the dorsal side of supine subjects, targeting clinical applications in hospitals ( 14 ).…”

Section: Introductionmentioning

confidence: 99%

SQUID magnetoneurography: an old-fashioned yet new tool for noninvasive functional imaging of spinal cords and peripheral nerves

Adachi,

Kawabata

2024

Front. Med. Technol.

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We are engaged in the development and clinical application of a neural magnetic field measurement system that utilizes biomagnetic measurements to observe the activity of the spinal cord and peripheral nerves. Unlike conventional surface potential measurements, biomagnetic measurements are not affected by the conductivity distribution within the body, making them less influenced by the anatomical structure of body tissues. Consequently, functional testing using biomagnetic measurements can achieve higher spatial resolution compared to surface potential measurements. The neural magnetic field measurement, referred to as magnetoneurography, takes advantage of these benefits to enable functional testing of the spinal cord and peripheral nerves, while maintaining high spatial resolution and noninvasiveness. Our magnetoneurograph system is based on superconducting quantum interference devices (SQUIDs) similar to the conventional biomagnetic measurement systems. Various design considerations have been incorporated into the SQUID sensor array structure and signal processing software to make it suitable for detecting neural signal propagation along spinal cord and peripheral nerve. The technical validation of this system began in 1999 with a 3-channel SQUID system. Over the course of more than 20 years, we have continued technological development through medical-engineering collaboration, and in the latest prototype released in 2020, neural function imaging of the spinal cord and peripheral nerves, which could also be applied for the diagnosis of neurological disorders, has become possible. This paper provides an overview of the technical aspects of the magnetoneurograph system, covering the measurement hardware and software perspectives for providing diagnostic information, and its applications. Additionally, we discuss the integration with a helium recondensing system, which is a key factor in reducing running costs and achieving practicality in hospitals.

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“…The liquid helium (LHe) cryostat was redesigned to optimize the detection of the spinal cord signals from the back of the neck, and the SQUID sensor array was improved for step-wise broadening of the observation area. Additionally, MSG systems applicable to human subjects in a reclining position were developed in the mid 2000s [11,12]. This was followed by expanding the scale of the sensor array to more than one hundred channels, and the system was optimized for subjects lying in a supine position within the scope of medical use in hospitals [13][14][15].…”

Section: Introductionmentioning

confidence: 99%

Recent advancements in the SQUID magnetospinogram system

Adachi

Kawai

Haruta

et al. 2017

Supercond. Sci. Technol.

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In this study, a new superconducting quantum interference device (SQUID) biomagnetic measurement system known as magnetospinogram (MSG) is developed. The MSG system is used for observation of a weak magnetic field distribution induced by the neural activity of the spinal cord over the body surface. The current source reconstruction for the observed magnetic field distribution provides noninvasive functional imaging of the spinal cord, which enables medical personnel to diagnose spinal cord diseases more accurately. The MSG system is equipped with a uniquely shaped cryostat and a sensor array of vector-type SQUID gradiometers that are designed to detect the magnetic field from deep sources across a narrow observation area over the body surface of supine subjects. The latest prototype of the MSG system is already applied in clinical studies to develop a diagnosis protocol for spinal cord diseases. Advancements in hardware and software for MSG signal processing and cryogenic components aid in effectively suppressing external magnetic field noise and reducing the cost of liquid helium that act as barriers with respect to the introduction of the MSG system to hospitals. The application of the MSG system is extended to various biomagnetic applications in addition to spinal cord functional imaging given the advantages of the MSG system for investigating deep sources. The study also includes a report on the recent advancements of the SQUID MSG system including its peripheral technologies and wide-spread applications.

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A 30-Channel SQUID Vector Biomagnetometer System Optimized for Reclining Subjects

Cited by 6 publications

References 8 publications

A 75-ch SQUID Biomagnetometer System for Human Cervical Spinal Cord Evoked Field

A 75-ch SQUID Biomagnetometer System for Human Cervical Spinal Cord Evoked Field

SQUID magnetoneurography: an old-fashioned yet new tool for noninvasive functional imaging of spinal cords and peripheral nerves

Recent advancements in the SQUID magnetospinogram system

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