Magnetospinography: Instruments and Application to Functional Imaging of Spinal Cords

Adachi, Yoshiaki; Oyama, Daisuke; Kawabata, Shigenori; Sekihara, Kensuke; Haruta, Yasuhiro; Uehara, Gen

doi:10.1587/transele.e96.c.326

Cited by 10 publications

(6 citation statements)

References 13 publications

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“…These limitations are overcome with magnetospinography (MSG) which uses superconducting quantum interference devices (SQUIDs) to detect the magnetic field generated by the spinal cord [22][23][24][25][26] . The magnetic fields detected with MSG are not as distorted by the tissue surrounding the spinal cord or muscle artefacts, meaning source analysis is more reliable 23,27 .…”

Section: Current Measures Of Spinal Activitymentioning

confidence: 99%

Concurrent spinal and brain imaging with optically pumped magnetometers

Mardell

O'Neill

Tierney

et al. 2022

Preprint

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The spinal cord and its interactions with the brain are fundamental for movement control and somatosensation. However, brain and spinal cord electrophysiology in humans have largely been treated as distinct enterprises, in part due to the relative inaccessibility of the spinal cord. Consequently, there is a dearth of knowledge on human spinal electrophysiology, including the multiple pathologies of the central nervous system that affect the spinal cord as well as the brain. Here we exploit recent advances in the development of wearable optically pumped magnetometers (OPMs) which can be flexibly arranged to provide coverage of both the spinal cord and the brain concurrently in unconstrained environments. Our system for magnetospinoencephalography (MSEG) measures both spinal and cortical signals simultaneously by employing a custom-made spinal scanning cast. We evidence the utility of such a system by recording simultaneous spinal and cortical evoked responses to median nerve stimulation, demonstrating the novel ability for concurrent non-invasive millisecond imaging of brain and spinal cord.

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Section: Current Measures Of Spinal Activitymentioning

confidence: 99%

Concurrent spinal and brain imaging with optically pumped magnetometers

Mardell

O'Neill

Tierney

et al. 2022

Preprint

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“…We first simulated spinal cord evoked field (SCEF) measurements distorted by large stimulus-induced artifacts. For data generation, we assumed the sensor array of a 120-channel biomagnetometer [5][7], which has been specifically developed for SCEF measurements. The biomagnetometer is equipped with 40 vector sensors 6 , which are arranged at 8 × 5 measurement locations covering a 14 cm×9 cm area.…”

Section: Computer Simulationmentioning

confidence: 99%

“…x ( ), r l j y ( ), and r l j z ( ). We define an Ḿ 3 matrix L r ( ) in which the jth row is equal to the row vector 5 Although the exact causes of these artifacts are still unknown, we speculate that they are caused by combined effects of stimulus-induced body electric currents and transient responses of receiver electronics.…”

Section: Sensor Lead Field and Signal Subspacementioning

confidence: 99%

“…Biomagnetometers optimized for measuring the spinal cord evoked magnetic field (SCEF) have been developed [5][6][7], along with efficient source reconstruction algorithms suited to functional spinal cord imaging [8,9]. However, one serious problem, the removal of large stimulus-induced artifacts 5 , remains to be solved. Such artifacts exist for 8-10 ms immediately after the stimulus onset.…”

Section: Introductionmentioning

confidence: 99%

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Dual signal subspace projection (DSSP): a novel algorithm for removing large interference in biomagnetic measurements

et al. 2016

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Objective In functional electrophysiological imaging, signals are often contaminated by interference that can be of considerable magnitude compared to the signals of interest. This paper proposes a novel algorithm for removing such interferences that does not require separate noise measurements. Approach The algorithm is based on a dual definition of the signal subspace in the spatial- and time-domains. Since the algorithm makes use of this duality, it is named the dual signal subspace projection (DSSP). The DSSP algorithm first projects the columns of the measured data matrix onto the inside and outside of the spatial-domain signal subspace, creating a set of two preprocessed data matrices. The intersection of the row spans of these two matrices is estimated as the time-domain interference subspace. The original data matrix is projected onto the subspace that is orthogonal to the interference subspace Main results The DSSP algorithm is validated first by using the computer generated data, and then by using two sets of real biomagnetic data: SCEF data measured from a healthy volunteer and MEG data from a patient with a vagus nerve stimulator. Significance The proposed DSSP algorithm is effective for removing overlapped interference in a wide variety of biomagnetic measurements.

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“…At present, to investigate higher brain functions noninvasively, a variety of imaging methods and tools, such as functional magnetic resonance imaging (fMRI), electroencephalograms (EEGs), near-infrared spectroscopy (NIRS), and magnetoencephalograms (MEGs), 1) have been used. In addition, magnetocardiograms (MCGs) 2,3) and magnetospinograms (MSGs) 4) have also been developed to diagnose diseases and biological disorders of the heart and spinal cord.…”

Section: Introductionmentioning

confidence: 99%

Human magnetoencephalogram measurements using newly developed compact module of high-sensitivity atomic magnetometer

Kamada

Daichi

Ito

et al. 2015

Jpn. J. Appl. Phys.

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In the field of biomagnetic measurements, optically pumped atomic magnetometers (OPAMs) are expected to be alternative sensors to magnetometers based on superconducting quantum interference devices (SQUIDs). In addition, miniaturized OPAMs are required for practical use. To address this issue, we developed a compact module of a high-sensitivity OPAM with a pump–probe arrangement and potassium used as the sensing atom. Because the noise spectrum density of the OPAM reached 21 fTrms/Hz1/2 at 10 Hz, we attempted to use it to measure human magnetocardiograms (MEGs). Compared with the results obtained with SQUID-based magnetometers, we could successfully observe distinct features of event-related desynchronization in the 8–13 Hz band associated with eye opening. The results demonstrate the feasibility of using the OPAM module for neuromagnetic field measurements.

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Magnetospinography: Instruments and Application to Functional Imaging of Spinal Cords

Cited by 10 publications

References 13 publications

Concurrent spinal and brain imaging with optically pumped magnetometers

Concurrent spinal and brain imaging with optically pumped magnetometers

Dual signal subspace projection (DSSP): a novel algorithm for removing large interference in biomagnetic measurements

Human magnetoencephalogram measurements using newly developed compact module of high-sensitivity atomic magnetometer

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