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Tanaka Y, Sasaki T, Kawabata S, Hashimoto J, Higashikawa H, Hoshino Y, Sekihara K, Adachi Y, Fujita K, Nimura A, Watanabe T, Miyano Y, Kaminaka S, Yamamoto Y, Yoshii T. Assessing ulnar neuropathy at the elbow using magnetoneurography. Clin Neurophysiol 2024; 161:180-187. [PMID: 38520798 DOI: 10.1016/j.clinph.2024.02.030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Revised: 02/09/2024] [Accepted: 02/23/2024] [Indexed: 03/25/2024]
Abstract
OBJECTIVE To measure neuromagnetic fields of ulnar neuropathy patients at the elbow after electrical stimulation and evaluate ulnar nerve function at the elbow with high spatial resolution. METHODS A superconducting quantum interference device magnetometer system recorded neuromagnetic fields of the ulnar nerve at the elbow after electrical stimulation at the wrist in 16 limbs of 16 healthy volunteers and 21 limbs of 20 patients with ulnar neuropathy at the elbow. After artifact removal, neuromagnetic field signals were processed into current distributions, which were superimposed onto X-ray images for visualization. RESULTS Based on the results in healthy volunteers, conduction velocity of 30 m/s or 50% attenuation in current amplitude was set as the reference value for conduction disturbance. Of the 21 patient limbs, 15 were measurable and lesion sites were detected, whereas 6 limbs were unmeasurable due to weak neuromagnetic field signals. Seven limbs were deemed normal by nerve conduction study, but 5 showed conduction disturbances on magnetoneurography. CONCLUSIONS Measuring the magnetic field after nerve stimulation enabled visualization of neurophysiological activity in patients with ulnar neuropathy at the elbow and evaluation of conduction disturbances. SIGNIFICANCE Magnetoneurography may be useful for assessing lesion sites in patients with ulnar neuropathy at the elbow.
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Affiliation(s)
- Yuta Tanaka
- Department of Orthopedic Surgery, Graduate school of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan.
| | - Toru Sasaki
- Department of Orthopedic Surgery, Graduate school of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan.
| | - Shigenori Kawabata
- Department of Orthopedic Surgery, Graduate school of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan; Department of Advanced Technology in Medicine, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan.
| | - Jun Hashimoto
- Department of Orthopedic Surgery, Graduate school of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan; Department of Advanced Technology in Medicine, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan.
| | - Hisato Higashikawa
- Department of Orthopedic Surgery, Graduate school of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan.
| | - Yuko Hoshino
- Department of Advanced Technology in Medicine, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan.
| | - Kensuke Sekihara
- Department of Advanced Technology in Medicine, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan.
| | - Yoshiaki Adachi
- Applied Electronics Laboratory, Kanazawa Institute of Technology, 7-1 Ogigaoka, Nonoichi, Kanazawa-shi, Ishikawa 920-1331, Japan
| | - Koji Fujita
- Department of Functional Joint Anatomy, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan.
| | - Akimoto Nimura
- Department of Functional Joint Anatomy, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan.
| | - Taishi Watanabe
- Ricoh Institute of Future Technology, RICOH Company, Ltd., 2-3-10 Kandasurugadai, Chiyoda-ku, Tokyo 101-0062, Japan.
| | - Yuki Miyano
- Ricoh Institute of Future Technology, RICOH Company, Ltd., 2-3-10 Kandasurugadai, Chiyoda-ku, Tokyo 101-0062, Japan.
| | - Saeri Kaminaka
- Ricoh Institute of Future Technology, RICOH Company, Ltd., 2-3-10 Kandasurugadai, Chiyoda-ku, Tokyo 101-0062, Japan.
| | - Yusuke Yamamoto
- Ricoh Institute of Future Technology, RICOH Company, Ltd., 2-3-10 Kandasurugadai, Chiyoda-ku, Tokyo 101-0062, Japan.
| | - Toshitaka Yoshii
- Department of Orthopedic Surgery, Graduate school of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan.
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Magnetoneurography as a novel functional imaging technique for the ulnar nerve at the elbow. Clin Neurophysiol 2022; 138:153-162. [DOI: 10.1016/j.clinph.2022.03.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 03/16/2022] [Accepted: 03/18/2022] [Indexed: 11/18/2022]
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Hashimoto J, Kawabata S, Sasaki T, Hoshino Y, Sekihara K, Adachi Y, Watanabe T, Miyano Y, Mitani Y, Sato S, Kim S, Yoshii T, Okawa A. Assessment of thoracic spinal cord electrophysiological activity through magnetoneurography. Clin Neurophysiol 2021; 133:39-47. [PMID: 34800837 DOI: 10.1016/j.clinph.2021.09.023] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 09/09/2021] [Accepted: 09/30/2021] [Indexed: 11/24/2022]
Abstract
OBJECTIVE Noninvasive and detailed visualization of electrophysiological activity in the thoracic spinal cord through magnetoneurography. METHODS In five healthy volunteers, magnetic fields around current flowing in the thoracic spinal cord after alternating unilateral and synchronized bilateral sciatic nerve stimulation were measured using a magnetoneurograph system with superconductive quantum interference device biomagnetometers. The current distribution was obtained from the magnetic data by spatial filtering and visualized by superimposing it on the X-ray image. Conduction velocity was calculated using the peak latency of the current waveforms. RESULTS A sufficiently high magnetic signal intensity and signal-to-noise ratio were obtained in all participants after synchronized bilateral sciatic nerve stimulation. Leading and trailing components along the spinal canal and inward components flowing into the depolarization site ascended to the upper thoracic spine. Conduction velocity of the inward current in the whole thoracic spine was 42.4 m/s. CONCLUSIONS Visualization of electrophysiological activity in the thoracic spinal cord was achieved through magnetoneurography and a new method for synchronized bilateral sciatic nerve stimulation. Magnetoneurography is expected to be a useful modality in functional assessment of thoracic myelopathy. SIGNIFICANCE This is the first report to use magnetoneurography to noninvasively visualize electrophysiological activity in the thoracic spinal cord in detail.
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Affiliation(s)
- Jun Hashimoto
- Department of Orthopaedic Surgery, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan.
| | - Shigenori Kawabata
- Department of Orthopaedic Surgery, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan; Department of Advanced Technology in Medicine, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan.
| | - Toru Sasaki
- Department of Orthopaedic Surgery, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan.
| | - Yuko Hoshino
- Department of Advanced Technology in Medicine, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan.
| | - Kensuke Sekihara
- Department of Advanced Technology in Medicine, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan.
| | - Yoshiaki Adachi
- Applied Electronics Laboratory, Kanazawa Institute of Technology, 3 Amaike-cho, Kanazawa City, Ishikawa 920-1331, Japan.
| | - Taishi Watanabe
- RICOH Company, Ltd., 1-3-6 Nakamagome, Ohta-ku, Tokyo 143-8555, Japan.
| | - Yuki Miyano
- RICOH Company, Ltd., 1-3-6 Nakamagome, Ohta-ku, Tokyo 143-8555, Japan.
| | - Yuki Mitani
- RICOH Company, Ltd., 1-3-6 Nakamagome, Ohta-ku, Tokyo 143-8555, Japan.
| | - Shinji Sato
- RICOH Company, Ltd., 1-3-6 Nakamagome, Ohta-ku, Tokyo 143-8555, Japan.
| | - Sukchan Kim
- RICOH Company, Ltd., 1-3-6 Nakamagome, Ohta-ku, Tokyo 143-8555, Japan.
| | - Toshitaka Yoshii
- Department of Orthopaedic Surgery, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan.
| | - Atsushi Okawa
- Department of Orthopaedic Surgery, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan.
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Akaza M, Kawabata S, Ozaki I, Miyano Y, Watanabe T, Adachi Y, Sekihara K, Sumi Y, Yokota T. Noninvasive measurement of sensory action currents in the cervical cord by magnetospinography. Clin Neurophysiol 2021; 132:382-391. [PMID: 33450561 DOI: 10.1016/j.clinph.2020.11.029] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Revised: 10/29/2020] [Accepted: 11/06/2020] [Indexed: 10/22/2022]
Abstract
OBJECTIVE To obtain magnetic recordings of electrical activities in the cervical cord and visualize sensory action currents of the dorsal column, intervertebral foramen, and dorsal horn. METHODS Neuromagnetic fields were measured at the neck surface upon median nerve stimulation at the wrist using a magnetospinography system with high-sensitivity superconducting quantum interference device sensors. Somatosensory evoked potentials (SEPs) were also recorded. Evoked electrical currents were reconstructed by recursive null-steering beamformer and superimposed on cervical X-ray images. RESULTS Estimated electrical currents perpendicular to the cervical cord ascended sequentially. Their peak latency at C5 and N11 peak latency of SEP were well-correlated in all 16 participants (r = 0.94, p < 0.0001). Trailing axonal currents in the intervertebral foramens were estimated in 10 participants. Estimated dorsal-ventral electrical currents were obtained within the spinal canal at C5. Current density peak latency significantly correlated with cervical N13-P13 peak latency of SEPs in 13 participants (r = 0.97, p < 0.0001). CONCLUSIONS Magnetospinography shows excellent spatial and temporal resolution after median nerve stimulation and can identify the spinal root entry level, calculate the dorsal column conduction velocity, and analyze segmental dorsal horn activity. SIGNIFICANCE This approach is useful for functional electrophysiological diagnosis of somatosensory pathways.
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Affiliation(s)
- Miho Akaza
- Respiratory and Nervous System Science, Biomedical Laboratory Science, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8519, Japan.
| | - Shigenori Kawabata
- Department of Advanced Technology in Medicine, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8519, Japan.
| | - Isamu Ozaki
- Department of Physical Therapy, Faculty of Health Sciences, Aomori University of Health and Welfare, 58-1 Mase, Hamadate, Aomori 030-8505, Japan.
| | - Yuki Miyano
- Healthcare Business Group, RICOH Company, Ltd., 2-3-10 Kandasurugadai Chiyoda-ku, Tokyo 101-0062, Japan.
| | - Taishi Watanabe
- Healthcare Business Group, RICOH Company, Ltd., 2-3-10 Kandasurugadai Chiyoda-ku, Tokyo 101-0062, Japan.
| | - Yoshiaki Adachi
- Applied Electronics Laboratory, Kanazawa Institute of Technology, 7-1 Ogigaoka, Nonoichi, Ishikawa 921-8501, Japan
| | - Kensuke Sekihara
- Department of Advanced Technology in Medicine, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8519, Japan.
| | - Yuki Sumi
- Respiratory and Nervous System Science, Biomedical Laboratory Science, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8519, Japan.
| | - Takanori Yokota
- Department of Neurology and Neurological Science, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8519, Japan.
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Evaluation of neural activity by magnetospinography with 3D sensors. Clin Neurophysiol 2020; 131:1252-1266. [PMID: 32299009 DOI: 10.1016/j.clinph.2020.02.025] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Revised: 01/10/2020] [Accepted: 02/15/2020] [Indexed: 11/24/2022]
Abstract
OBJECTIVE Magnetospinography (MSG) has been developed for clinical application and is expected to be a novel neurophysiological examination. Here, we used an MSG system with sensors positioned in three orthogonal directions to record lumbar canal evoked magnetic fields (LCEFs) in response to peripheral nerve stimulation and to evaluate methods for localizing spinal cord lesions. METHODS LCEFs from the lumbar area of seven rabbits were recorded by the MSG system in response to electrical stimulation of a sciatic nerve. LCEFs and lumbar canal evoked potentials (LCEPs) were measured before and after spinal cord compression induced by a balloon catheter. The lesion positions were estimated using LCEPs and computationally reconstructed currents corresponding to the depolarization site. RESULTS LCEFs were recorded in all rabbits and neural activity in the lumbar spinal cord could be visualized in the form of a magnetic contour map and reconstructed current map. The position of the spinal cord lesion could be estimated by the LCEPs and reconstructed currents at the depolarization site. CONCLUSIONS MSG can visualize neural activity in the spinal cord and localize the lesion site. SIGNIFICANCE MSG enables noninvasive assessment of neural activity in the spinal canal using currents at depolarization sites reconstructed from LCEFs.
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Novel functional imaging technique for the brachial plexus based on magnetoneurography. Clin Neurophysiol 2019; 130:2114-2123. [PMID: 31542709 DOI: 10.1016/j.clinph.2019.08.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Revised: 08/02/2019] [Accepted: 08/12/2019] [Indexed: 02/05/2023]
Abstract
OBJECTIVE To visualize neural activity in the brachial plexus using magnetoneurography (MNG). METHODS Using a 124- or 132-channel biomagnetometer system with a superconducting quantum interference device, neuromagnetic fields above the clavicle and neck region were recorded in response to electrical stimulation of the median and ulnar nerves in five asymptomatic volunteers (four men and one woman; age, 27-45 years old). Equivalent currents were computationally reconstructed from neuromagnetic fields and visualized as pseudocolor maps. Reconstructed currents at the depolarization site and compound nerve action potentials (CNAPs) at Erb's point were compared. RESULTS Neuromagnetic fields were recorded in all subjects. The reconstructed equivalent currents propagated into the vertebral foramina, and the main inflow levels differed between the median nerve (C5/C6-C7/T1 vertebral foramen) and the ulnar nerve (C7/T1-T1/T2). The inward current peaks at the depolarization site and CNAPs showed high linear correlation. CONCLUSIONS MNG visualizes neural activity in the brachial plexus and can differentiate the conduction pathways after median and ulnar nerve stimulations. In addition, it can visualize not only the leading and trailing components of intra-axonal currents, but also inward currents at the depolarization site. SIGNIFICANCE MNG is a novel and promising functional imaging modality for the brachial plexus.
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Ushio S, Hoshino Y, Kawabata S, Adachi Y, Sekihara K, Sumiya S, Ukegawa D, Sakaki K, Watanabe T, Hasegawa Y, Okawa A. Visualization of the electrical activity of the cauda equina using a magnetospinography system in healthy subjects. Clin Neurophysiol 2018; 130:1-11. [PMID: 30471467 DOI: 10.1016/j.clinph.2018.11.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Revised: 10/24/2018] [Accepted: 11/02/2018] [Indexed: 01/12/2023]
Abstract
OBJECTIVE To establish a method to measure cauda equina action fields (CEAFs) and visualize the electrical activities of the cauda equina in a broadly aged group of healthy adults. METHODS Using a 124-channel magnetospinography (MSG) system with superconducting interference devices, the CEAFs of 43 healthy volunteers (22-64 years of age) were measured after stimulation of the peroneal nerve at the knee. Reconstructed currents were obtained from the CEAFs and superimposed on the X-ray image. Conduction velocities were also calculated from the waveform of the reconstructed currents. RESULTS The reconstructed currents were successfully visualized. They flowed into the L5/S1 foramen about 8.25-8.95 ms after the stimulation and propagated cranially along the spinal canal. In 32 subjects (74%), the conduction velocities of the reconstructed currents in the cauda equina could be calculated from the peak latency at the L2-L5 level. CONCLUSIONS MSG visualized the electrical activity of the cauda equina after peroneal nerve stimulation in healthy adults. In addition, the conduction velocities of the reconstructed currents in the cauda equina could be calculated, despite previously being difficult to measure. SIGNIFICANCE MSG has the potential to be a novel and noninvasive functional examination for lumbar spinal disease.
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Affiliation(s)
- Shuta Ushio
- Department of Orthopedic Surgery, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan.
| | - Yuko Hoshino
- Department of Advanced Technology in Medicine, Graduate School of Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan.
| | - Shigenori Kawabata
- Department of Orthopedic Surgery, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan; Department of Advanced Technology in Medicine, Graduate School of Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan.
| | - Yoshiaki Adachi
- Applied Electronics Laboratory, Kanazawa Institute of Technology, Kanazawa-shi, Ishikawa 920-1331, Japan
| | - Kensuke Sekihara
- Department of Advanced Technology in Medicine, Graduate School of Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan.
| | - Satoshi Sumiya
- Department of Orthopedic Surgery, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan
| | - Dai Ukegawa
- Department of Orthopedic Surgery, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan.
| | - Kyohei Sakaki
- Department of Orthopedic Surgery, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan
| | - Taishi Watanabe
- Department of Orthopedic Surgery, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan; RICOH Company, Ltd., 16-1 Shinei-cho, Tsuzuki-ku, Yokohama, Kanagawa 224-0035, Japan
| | - Yuki Hasegawa
- Department of Advanced Technology in Medicine, Graduate School of Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan
| | - Atsushi Okawa
- Department of Orthopedic Surgery, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan.
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Polyacrylamide Ferrogels with Magnetite or Strontium Hexaferrite: Next Step in the Development of Soft Biomimetic Matter for Biosensor Applications. SENSORS 2018; 18:s18010257. [PMID: 29337918 PMCID: PMC5795928 DOI: 10.3390/s18010257] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Revised: 01/09/2018] [Accepted: 01/15/2018] [Indexed: 12/25/2022]
Abstract
Magnetic biosensors are an important part of biomedical applications of magnetic materials. As the living tissue is basically a "soft matter." this study addresses the development of ferrogels (FG) with micron sized magnetic particles of magnetite and strontium hexaferrite mimicking the living tissue. The basic composition of the FG comprised the polymeric network of polyacrylamide, synthesized by free radical polymerization of monomeric acrylamide (AAm) in water solution at three levels of concentration (1.1 M, 0.85 M and 0.58 M) to provide the FG with varying elasticity. To improve FG biocompatibility and to prevent the precipitation of the particles, polysaccharide thickeners-guar gum or xanthan gum were used. The content of magnetic particles in FG varied up to 5.2 wt % depending on the FG composition. The mechanical properties of FG and their deformation in a uniform magnetic field were comparatively analyzed. FG filled with strontium hexaferrite particles have larger Young's modulus value than FG filled with magnetite particles, most likely due to the specific features of the adhesion of the network's polymeric subchains on the surface of the particles. FG networks with xanthan are stronger and have higher modulus than the FG with guar. FG based on magnetite, contract in a magnetic field 0.42 T, whereas some FG based on strontium hexaferrite swell. Weak FG with the lowest concentration of AAm shows a much stronger response to a field, as the concentration of AAm governs the Young's modulus of ferrogel. A small magnetic field magnetoimpedance sensor prototype with Co68.6Fe3.9Mo3.0Si12.0B12.5 rapidly quenched amorphous ribbon based element was designed aiming to develop a sensor working with a disposable stripe sensitive element. The proposed protocol allowed measurements of the concentration dependence of magnetic particles in gels using magnetoimpedance responses in the presence of magnetite and strontium hexaferrite ferrogels with xanthan. We have discussed the importance of magnetic history for the detection process and demonstrated the importance of remnant magnetization in the case of the gels with large magnetic particles.
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Sumiya S, Kawabata S, Hoshino Y, Adachi Y, Sekihara K, Tomizawa S, Tomori M, Ishii S, Sakaki K, Ukegawa D, Ushio S, Watanabe T, Okawa A. Magnetospinography visualizes electrophysiological activity in the cervical spinal cord. Sci Rep 2017; 7:2192. [PMID: 28526877 PMCID: PMC5438392 DOI: 10.1038/s41598-017-02406-8] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Accepted: 04/11/2017] [Indexed: 11/09/2022] Open
Abstract
Diagnosis of nervous system disease is greatly aided by functional assessments and imaging techniques that localize neural activity abnormalities. Electrophysiological methods are helpful but often insufficient to locate neural lesions precisely. One proposed noninvasive alternative is magnetoneurography (MNG); we have developed MNG of the spinal cord (magnetospinography, MSG). Using a 120-channel superconducting quantum interference device biomagnetometer system in a magnetically shielded room, cervical spinal cord evoked magnetic fields (SCEFs) were recorded after stimulation of the lower thoracic cord in healthy subjects and a patient with cervical spondylotic myelopathy and after median nerve stimulation in healthy subjects. Electrophysiological activities in the spinal cord were reconstructed from SCEFs and visualized by a spatial filter, a recursive null-steering beamformer. Here, we show for the first time that MSG with high spatial and temporal resolution can be used to map electrophysiological activities in the cervical spinal cord and spinal nerve.
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Affiliation(s)
- Satoshi Sumiya
- Department of Orthopaedic Surgery, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan
| | - Shigenori Kawabata
- Department of Orthopaedic Surgery, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan. .,Department of Advanced Technology in Medicine, Graduate School of Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan.
| | - Yuko Hoshino
- Department of Advanced Technology in Medicine, Graduate School of Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan
| | - Yoshiaki Adachi
- Applied Electronics Laboratory, Kanazawa Institute of Technology, Kanazawa-shi, Ishikawa, 920-1331, Japan
| | - Kensuke Sekihara
- Department of Advanced Technology in Medicine, Graduate School of Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan
| | - Shoji Tomizawa
- Department of Orthopaedic Surgery, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan
| | - Masaki Tomori
- Department of Orthopaedic Surgery, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan
| | - Senichi Ishii
- Department of Orthopaedic Surgery, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan
| | - Kyohei Sakaki
- Department of Orthopaedic Surgery, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan
| | - Dai Ukegawa
- Department of Orthopaedic Surgery, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan
| | - Shuta Ushio
- Department of Orthopaedic Surgery, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan
| | - Taishi Watanabe
- Ricoh Institute of Future Technology, RICOH COMPANY, LTD., 16-1 Shinei-cho, Tsuzuki-ku, Yokohama-shi, Kanagawa, 224-0034, Japan
| | - Atsushi Okawa
- Department of Orthopaedic Surgery, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan
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