JP5865376B2 - 電気インピーダンストモグラフィーイメージング用センサデバイス - Google Patents

電気インピーダンストモグラフィーイメージング用センサデバイス Download PDF

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JP5865376B2
JP5865376B2 JP2013532023A JP2013532023A JP5865376B2 JP 5865376 B2 JP5865376 B2 JP 5865376B2 JP 2013532023 A JP2013532023 A JP 2013532023A JP 2013532023 A JP2013532023 A JP 2013532023A JP 5865376 B2 JP5865376 B2 JP 5865376B2
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sensor
eit
electrode array
spatial
orientation
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JP2013540523A5 (enExample
JP2013540523A (ja
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ブルナー,ジョセフ,エックス
ギャゲロ,パスカル,オリヴィエール
ロバタイユ,ニコラス
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スイストム・アーゲー
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    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61BDIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00Measuring for diagnostic purposes; Identification of persons
    • A61B5/02Detecting, measuring or recording for evaluating the cardiovascular system, e.g. pulse, heart rate, blood pressure or blood flow
    • A61B5/0205Simultaneously evaluating both cardiovascular conditions and different types of body conditions, e.g. heart and respiratory condition
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61BDIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00Measuring for diagnostic purposes; Identification of persons
    • A61B5/05Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves
    • A61B5/053Measuring electrical impedance or conductance of a portion of the body
    • A61B5/0536Impedance imaging, e.g. by tomography
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61BDIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00Measuring for diagnostic purposes; Identification of persons
    • A61B5/06Devices, other than using radiation, for detecting or locating foreign bodies ; Determining position of diagnostic devices within or on the body of the patient
    • A61B5/061Determining position of a probe within the body employing means separate from the probe, e.g. sensing internal probe position employing impedance electrodes on the surface of the body
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61BDIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00Measuring for diagnostic purposes; Identification of persons
    • A61B5/08Measuring devices for evaluating the respiratory organs
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61BDIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00Measuring for diagnostic purposes; Identification of persons
    • A61B5/103Measuring devices for testing the shape, pattern, colour, size or movement of the body or parts thereof, for diagnostic purposes
    • A61B5/11Measuring movement of the entire body or parts thereof, e.g. head or hand tremor or mobility of a limb
    • A61B5/113Measuring movement of the entire body or parts thereof, e.g. head or hand tremor or mobility of a limb occurring during breathing
    • A61B5/1135Measuring movement of the entire body or parts thereof, e.g. head or hand tremor or mobility of a limb occurring during breathing by monitoring thoracic expansion
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61BDIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00Measuring for diagnostic purposes; Identification of persons
    • A61B5/24Detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof
    • A61B5/25Bioelectric electrodes therefor
    • A61B5/279Bioelectric electrodes therefor specially adapted for particular uses
    • A61B5/28Bioelectric electrodes therefor specially adapted for particular uses for electrocardiography [ECG]
    • A61B5/282Holders for multiple electrodes
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61BDIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00Measuring for diagnostic purposes; Identification of persons
    • A61B5/68Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient
    • A61B5/6801Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient specially adapted to be attached to or worn on the body surface
    • A61B5/6802Sensor mounted on worn items
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61BDIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00Measuring for diagnostic purposes; Identification of persons
    • A61B5/68Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient
    • A61B5/6801Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient specially adapted to be attached to or worn on the body surface
    • A61B5/683Means for maintaining contact with the body
    • A61B5/6831Straps, bands or harnesses
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61BDIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B7/00Instruments for auscultation
    • A61B7/003Detecting lung or respiration noise

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  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Surgery (AREA)
  • Veterinary Medicine (AREA)
  • Public Health (AREA)
  • General Health & Medical Sciences (AREA)
  • Animal Behavior & Ethology (AREA)
  • Biomedical Technology (AREA)
  • Heart & Thoracic Surgery (AREA)
  • Medical Informatics (AREA)
  • Molecular Biology (AREA)
  • Pathology (AREA)
  • Biophysics (AREA)
  • Physics & Mathematics (AREA)
  • Physiology (AREA)
  • Pulmonology (AREA)
  • Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
  • Cardiology (AREA)
  • Radiology & Medical Imaging (AREA)
  • Human Computer Interaction (AREA)
  • Dentistry (AREA)
  • Oral & Maxillofacial Surgery (AREA)
  • Measurement And Recording Of Electrical Phenomena And Electrical Characteristics Of The Living Body (AREA)
  • Measurement Of The Respiration, Hearing Ability, Form, And Blood Characteristics Of Living Organisms (AREA)
JP2013532023A 2010-10-07 2011-10-04 電気インピーダンストモグラフィーイメージング用センサデバイス Active JP5865376B2 (ja)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
CH16382010 2010-10-07
CH1638/10 2010-10-07
PCT/CH2011/000236 WO2012045188A1 (en) 2010-10-07 2011-10-04 Sensor device for electrical impedance tomography imaging, electrical impedance tomography imaging intrument and electrical impeance tomography method

Related Child Applications (1)

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JP2015200888A Division JP6093421B2 (ja) 2010-10-07 2015-10-09 電気インピーダンストモグラフィーイメージング計器及び電気インピーダンストモグラフィーイメージング方法

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JP2013540523A JP2013540523A (ja) 2013-11-07
JP2013540523A5 JP2013540523A5 (enExample) 2014-11-27
JP5865376B2 true JP5865376B2 (ja) 2016-02-17

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JP2013532023A Active JP5865376B2 (ja) 2010-10-07 2011-10-04 電気インピーダンストモグラフィーイメージング用センサデバイス
JP2015200888A Active JP6093421B2 (ja) 2010-10-07 2015-10-09 電気インピーダンストモグラフィーイメージング計器及び電気インピーダンストモグラフィーイメージング方法

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US (2) US10548484B2 (enExample)
EP (1) EP2624750B1 (enExample)
JP (2) JP5865376B2 (enExample)
CN (1) CN103153180B (enExample)
BR (1) BR112013007147A2 (enExample)
WO (1) WO2012045188A1 (enExample)

Families Citing this family (38)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103153180B (zh) * 2010-10-07 2015-07-29 斯威斯托姆公开股份有限公司 用于电阻抗断层成像的传感器装置、电阻抗断层成像装置和电阻抗断层成像方法
EP2903512A4 (en) * 2012-10-03 2016-07-06 Univ Ramot PARAMETRIC ELECTRICAL IMPEDANCE TOMOGRAPHY OF CHEST
BR102012028367B1 (pt) * 2012-11-06 2022-03-22 Timpel S.A Método e aparato para gerar e exibir uma representação simplificada de informações obtidas através de tomografia por impedância elétrica
DE102013203177A1 (de) * 2013-02-26 2014-08-28 Hamilton Medical Ag System zur automatisierten Einstellung eines durch eine Beatmungseinrichtung vorgegebenen Drucks
US11457832B2 (en) * 2013-07-02 2022-10-04 School Juridical Person Kitasato Institute Measurement device, shape estimation device, measurement method, shape estimation method, and non-transitory recording medium recording program
JP6385929B2 (ja) * 2013-07-02 2018-09-05 学校法人北里研究所 Eit測定装置、eit測定方法及びプログラム
US10952634B2 (en) 2013-10-04 2021-03-23 Swisstom Ag Electrical impedance tomography system
US10283162B2 (en) 2014-02-05 2019-05-07 Avatar Merger Sub II, LLC Method for triggering events in a video
DE102014004392A1 (de) 2014-03-26 2015-10-15 Epsilon Bootes - Pi Entwicklung Von Trainingswissenschaftlichen Sportgeräten E.K. Mobile Spiroergometrie, EEG, 4D-EIT mit 4D-Ultraschall, Startzeit Zwischenzeitregistration Eindzeit, Schwimm Laufwiederstand Zug gerät, Venen Arterien Wahrnehmende 4D-Kamera als Einheit oder Individuell im Verarbeitsprozessor Bio-Physiologische als Megani
CN106535756A (zh) * 2014-05-30 2017-03-22 拉菲尔·霍尔兹哈克 用于捕获身体信号的模块
CN104605850B (zh) * 2015-01-19 2017-08-01 中山大学 一种基于电阻抗断层成像技术的膀胱尿量实时监测装置和方法
US10116901B2 (en) 2015-03-18 2018-10-30 Avatar Merger Sub II, LLC Background modification in video conferencing
CN105976411B (zh) * 2016-05-18 2017-06-20 中国人民解放军第四军医大学 一种用于电阻抗断层成像数据采集系统的前置测量模块及标校方法
CN105997096B (zh) * 2016-06-22 2019-04-26 合肥诺和电子科技有限公司 基于3d加速计的电阻抗断层肺成像方法
CN110139603B (zh) * 2016-11-11 2023-11-10 申特克股份公司 用于新生儿电阻抗断层成像的传感器带和定位辅助
KR101812587B1 (ko) * 2016-11-18 2018-01-30 주식회사 바이랩 피험자의 영상 모니터링 장치 및 그 방법과, 영상 모니터링 시스템
KR102788646B1 (ko) * 2017-01-24 2025-03-28 아나로그 디바이시즈 인코포레이티드 건강을 모니터링하기 위한 다수-센서 디바이스
EP3684463B1 (en) 2017-09-19 2025-05-14 Neuroenhancement Lab, LLC Method and apparatus for neuroenhancement
US11412946B2 (en) 2017-11-14 2022-08-16 Timpel Medical B.V. Electrical impedance tomography device and system having a multi-dimensional electrode arrangement
US11717686B2 (en) 2017-12-04 2023-08-08 Neuroenhancement Lab, LLC Method and apparatus for neuroenhancement to facilitate learning and performance
US12280219B2 (en) 2017-12-31 2025-04-22 NeuroLight, Inc. Method and apparatus for neuroenhancement to enhance emotional response
US11318277B2 (en) 2017-12-31 2022-05-03 Neuroenhancement Lab, LLC Method and apparatus for neuroenhancement to enhance emotional response
JP6731435B2 (ja) * 2018-03-16 2020-07-29 ティンペル・メディカル・ベー・フェー 生体信号検出モジュール
US11364361B2 (en) 2018-04-20 2022-06-21 Neuroenhancement Lab, LLC System and method for inducing sleep by transplanting mental states
KR102219685B1 (ko) * 2018-06-18 2021-02-24 주식회사 바이랩 저호흡 모니터링 시스템 및 방법
EP3849410A4 (en) 2018-09-14 2022-11-02 Neuroenhancement Lab, LLC System and method of improving sleep
DE102018008545A1 (de) * 2018-11-01 2020-05-07 Drägerwerk AG & Co. KGaA Vorrichtung und Verfahren zur Elektro-lmpedanz-Tomographie (EIT) mit Ermittlung einer Herzregion
WO2020234813A1 (en) * 2019-05-20 2020-11-26 Udayan Kanade System and method for acquiring electrical impedance tomography data
US11786694B2 (en) 2019-05-24 2023-10-17 NeuroLight, Inc. Device, method, and app for facilitating sleep
JP7375183B2 (ja) * 2019-10-07 2023-11-07 ティンペル・メディカル・ベー・フェー 局所的インピーダンス及び患者の配置を介しての肺の特徴の分析のためのデバイス、システム、及び方法
JP7767288B2 (ja) 2019-12-23 2025-11-11 アリメトリー リミテッド 電極パッチおよび接続システム
JP7443530B2 (ja) * 2019-12-30 2024-03-05 ティンペル・メディカル・ベー・フェー 電気インピーダンス測定を使用した血行力学の評価
JP2022006490A (ja) 2020-06-24 2022-01-13 朝日インテック株式会社 医療システム、および、画像生成方法
TWI740586B (zh) * 2020-07-28 2021-09-21 麗臺科技股份有限公司 利用週期性生理訊號產生電阻抗體層成像方法與裝置
CN112231997B (zh) * 2020-09-25 2023-04-07 重庆大学 基于人体组织电导率精细化建模设计的胸腔电阻抗仿真方法
CN114847913B (zh) * 2022-04-14 2023-10-27 四川大学华西医院 一种生物电阻抗断层成像装置和方法
CN115137340A (zh) * 2022-05-16 2022-10-04 思澜科技(成都)有限公司 一种用于eit成像的装置、系统及方法
WO2024127069A1 (en) 2022-12-15 2024-06-20 Ceske Vysoke Uceni Technicke V Praze System for increasing precision of electric impedance tomography

Family Cites Families (26)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6005916A (en) 1992-10-14 1999-12-21 Techniscan, Inc. Apparatus and method for imaging with wavefields using inverse scattering techniques
GB9226376D0 (en) 1992-12-18 1993-02-10 British Tech Group Tomography
DE19857090A1 (de) 1998-12-10 2000-06-29 Stephan Boehm Verfahren zur regionalen Bestimmung des alveolären Öffnens und des alveolären Schließens der Lunge
US7096061B2 (en) * 2002-07-03 2006-08-22 Tel-Aviv University Future Technology Development L.P. Apparatus for monitoring CHF patients using bio-impedance technique
US7226422B2 (en) * 2002-10-09 2007-06-05 Cardiac Pacemakers, Inc. Detection of congestion from monitoring patient response to a recumbent position
US8672852B2 (en) * 2002-12-13 2014-03-18 Intercure Ltd. Apparatus and method for beneficial modification of biorhythmic activity
GB2396426B (en) * 2002-12-21 2005-08-24 Draeger Medical Ag Artificial respiration system
DE10301202B3 (de) 2002-12-21 2004-01-22 Dräger Medical AG & Co. KGaA Beatmungssystem
DE10315863B4 (de) * 2003-04-08 2013-03-14 Dräger Medical GmbH Elektrodengürtel
US20040236202A1 (en) * 2003-05-22 2004-11-25 Burton Steven Angell Expandable strap for use in electrical impedance tomography
US20090131759A1 (en) * 2003-11-04 2009-05-21 Nathaniel Sims Life sign detection and health state assessment system
US20050107833A1 (en) 2003-11-13 2005-05-19 Freeman Gary A. Multi-path transthoracic defibrillation and cardioversion
JP4633374B2 (ja) * 2004-03-10 2011-02-16 公立大学法人会津大学 生体センサ装置
KR101103487B1 (ko) * 2004-03-29 2012-01-11 케이씨아이 라이센싱 인코포레이티드 복수 개의 폐의 위치에 따라서 환자의 폐를 환기하기위하여 인공호흡기의 적어도 하나의 환기 파라미터를제어하는 방법과 장치
EP3539463A1 (en) * 2005-04-14 2019-09-18 Hidalgo Limited Apparatus and system for monitoring
WO2006121469A1 (en) 2005-05-06 2006-11-16 The General Hospital Corporation Apparatuses and methods for electrophysiological signal delivery and recording during mri
US9089275B2 (en) * 2005-05-11 2015-07-28 Cardiac Pacemakers, Inc. Sensitivity and specificity of pulmonary edema detection when using transthoracic impedance
WO2007070997A1 (en) * 2005-12-20 2007-06-28 Dixtal Biomedica Industria E Comercio Ltda. Electrode assembly for electrical impedance tomography
CN101248989B (zh) * 2007-02-25 2011-10-12 香港中文大学 一种生理参数的监测系统
EP2162059B1 (en) * 2007-06-12 2021-01-13 Sotera Wireless, Inc. Vital sign monitor and method for measuring blood pressure using optical, electrical, and pressure waveforms
US8140154B2 (en) * 2007-06-13 2012-03-20 Zoll Medical Corporation Wearable medical treatment device
US8808193B2 (en) 2007-09-11 2014-08-19 Carefusion 207, Inc. Regional oxygen uptake/perfusion measuring device and method
WO2009042637A2 (en) * 2007-09-24 2009-04-02 Oregon Health & Science University Non-invasive location and tracking of tumors and other tissues for radiation therapy
EP2228009B1 (en) * 2009-03-09 2018-05-16 Drägerwerk AG & Co. KGaA Apparatus and method to determine functional lung characteristics
CN101564294B (zh) * 2009-06-01 2011-04-20 中国人民解放军第四军医大学 一种结构信息融合的电阻抗断层成像方法
CN103153180B (zh) 2010-10-07 2015-07-29 斯威斯托姆公开股份有限公司 用于电阻抗断层成像的传感器装置、电阻抗断层成像装置和电阻抗断层成像方法

Also Published As

Publication number Publication date
US10548484B2 (en) 2020-02-04
JP2016039914A (ja) 2016-03-24
BR112013007147A2 (pt) 2016-06-14
CN103153180B (zh) 2015-07-29
JP6093421B2 (ja) 2017-03-08
US20130190577A1 (en) 2013-07-25
EP2624750B1 (en) 2014-12-17
US11317815B2 (en) 2022-05-03
EP2624750A1 (en) 2013-08-14
CN103153180A (zh) 2013-06-12
JP2013540523A (ja) 2013-11-07
WO2012045188A1 (en) 2012-04-12
US20200146560A1 (en) 2020-05-14

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