CA2354549C - Fmri compatible electrode and electrode placement techniques - Google Patents
Fmri compatible electrode and electrode placement techniques Download PDFInfo
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- CA2354549C CA2354549C CA2354549A CA2354549A CA2354549C CA 2354549 C CA2354549 C CA 2354549C CA 2354549 A CA2354549 A CA 2354549A CA 2354549 A CA2354549 A CA 2354549A CA 2354549 C CA2354549 C CA 2354549C
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- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 claims description 4
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 claims description 4
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Classifications
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/24—Detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof
- A61B5/25—Bioelectric electrodes therefor
- A61B5/279—Bioelectric electrodes therefor specially adapted for particular uses
- A61B5/291—Bioelectric electrodes therefor specially adapted for particular uses for electroencephalography [EEG]
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- Life Sciences & Earth Sciences (AREA)
- Health & Medical Sciences (AREA)
- Medical Informatics (AREA)
- Biophysics (AREA)
- Pathology (AREA)
- Engineering & Computer Science (AREA)
- Biomedical Technology (AREA)
- Heart & Thoracic Surgery (AREA)
- Physics & Mathematics (AREA)
- Molecular Biology (AREA)
- Surgery (AREA)
- Animal Behavior & Ethology (AREA)
- General Health & Medical Sciences (AREA)
- Public Health (AREA)
- Veterinary Medicine (AREA)
- Magnetic Resonance Imaging Apparatus (AREA)
Abstract
In a brainwave acquisition system, an electrode positioning system includes a stretchable elastic cap (10), soft rubber electrode holders (20a), conductive recording electrodes (not numbered), where the electrodes are composed of materials such as metal, plastic or carbon, and conductive lead wires (13) are composed of materials such as metal or carbon conductive materials. No ferromagnetic materials of any kind are used in the construction of the system, and therefore, the system will not introduce unwanted contamination of functional Magnetic Resonance Imaging (MRI) data.
Description
WO 00/2727 _PCT/US99/26459 fMRI COMPATIBLE ELECTRODE AND ELECTRODE
PLACEMENT TECHNIQUES
Field of the Invention The present invention relates to medical devices and more specifically to techniques for acquiring uncontaminated electrical signals from the brain and body, without the use of pre-amplification eiecaonics, especially while located within the harsh operating environment produced by a function magnetic resonance imaging (th'flU system.
Background of the Related Art Conventional EEG, EOG, ECG, EMG, and other physiological signals are typically recorded using individually placed electrodes that arc ced- on the scalp and body with adhesives or by the use of a cap type system.
Examples of these techniques are those developed by San-ms et al (U.S. Pat.
No.
4,085,739) or Gevins et al (U.S. Pat No's 4,967,038 and 5,038,782). In these placement methods, the electrodes are attached to amplifi-cs to acquire and record the related electrical. and physiological activity. These amplifier systems require a very low impedance contact with the skin and are very su nibie to emissions from other electrical eauiDmeat, such as an IVU I
device. In such an environment, the input stage of a conventional EEG, ECG
or EMG amplifier is susceptible to, the very large - induced electrical and magnetic fields generated by a magnetic resonance imager to the point where the amplifier cannot function properly. In addition, these amplifier systems are almost always powered from an AC Voltage source and, therefore, radiate e06--magnetic interference which causes contamination of the {EMI), .
... .
anatomical and functional data acquired by the fMRI system and compromises the integrity of these data.
A prior attempt to collect EEG signals within the fMRI environment, by Ives et al (U.S. Pat. No. 5,445,162) is based on a battery powered analog pre-amplifier system in which individual electrodes are glued to the scalp and the electrical activity is amplified within the bore of the imaging device.
The signals are then converted to light energy by additional analog circuits placed nearby the patient. While still within the harsh fMRI environment, these signals are communicated along fiber-optic cables outside the shielded room, which protects the imaging equipment from unwanted interference, to a secondary amplifier system that is located outside the shielded room and attached to a PC for collecting and processing the data. However, this optically coupled pre-amplification system is expensive,- bulky, and, cumbersome to operate. In addition, due to size restrictions within the head coil (located inside the imager) and the inability to use digital circuits in the design, due to broadcast interference from internal clock circuits, the AC-coupled nature of this devices makes it susceptible to large artifacts caused by transient signals produced during normal operation of the imaging system.
Summary of the Invention The problems of the prior art, described above, are solved, in accordance with the present invention, by providing an EEG Electrode Positioning System using an elastic head cap (hereinafter Quik-Cap), to position- electrodes on the head and face to acquire electrical signals and 2S communicate them to external amplifier equipment. The Quik-Cap provides a stretchable elastic cap and chinstrap portion capable of comfortably fitting a wide range of head size and shape variability. The Quik-Cap provides a plurality of electrode holders designed to be filled with a conductive electrolyte.. In addition, the Quik-Cap provides a wire harness assembly that -30 can be configured with either carbon or metal lead wires and is capable of interfacing with any type of commercially available amplifier system.
PLACEMENT TECHNIQUES
Field of the Invention The present invention relates to medical devices and more specifically to techniques for acquiring uncontaminated electrical signals from the brain and body, without the use of pre-amplification eiecaonics, especially while located within the harsh operating environment produced by a function magnetic resonance imaging (th'flU system.
Background of the Related Art Conventional EEG, EOG, ECG, EMG, and other physiological signals are typically recorded using individually placed electrodes that arc ced- on the scalp and body with adhesives or by the use of a cap type system.
Examples of these techniques are those developed by San-ms et al (U.S. Pat.
No.
4,085,739) or Gevins et al (U.S. Pat No's 4,967,038 and 5,038,782). In these placement methods, the electrodes are attached to amplifi-cs to acquire and record the related electrical. and physiological activity. These amplifier systems require a very low impedance contact with the skin and are very su nibie to emissions from other electrical eauiDmeat, such as an IVU I
device. In such an environment, the input stage of a conventional EEG, ECG
or EMG amplifier is susceptible to, the very large - induced electrical and magnetic fields generated by a magnetic resonance imager to the point where the amplifier cannot function properly. In addition, these amplifier systems are almost always powered from an AC Voltage source and, therefore, radiate e06--magnetic interference which causes contamination of the {EMI), .
... .
anatomical and functional data acquired by the fMRI system and compromises the integrity of these data.
A prior attempt to collect EEG signals within the fMRI environment, by Ives et al (U.S. Pat. No. 5,445,162) is based on a battery powered analog pre-amplifier system in which individual electrodes are glued to the scalp and the electrical activity is amplified within the bore of the imaging device.
The signals are then converted to light energy by additional analog circuits placed nearby the patient. While still within the harsh fMRI environment, these signals are communicated along fiber-optic cables outside the shielded room, which protects the imaging equipment from unwanted interference, to a secondary amplifier system that is located outside the shielded room and attached to a PC for collecting and processing the data. However, this optically coupled pre-amplification system is expensive,- bulky, and, cumbersome to operate. In addition, due to size restrictions within the head coil (located inside the imager) and the inability to use digital circuits in the design, due to broadcast interference from internal clock circuits, the AC-coupled nature of this devices makes it susceptible to large artifacts caused by transient signals produced during normal operation of the imaging system.
Summary of the Invention The problems of the prior art, described above, are solved, in accordance with the present invention, by providing an EEG Electrode Positioning System using an elastic head cap (hereinafter Quik-Cap), to position- electrodes on the head and face to acquire electrical signals and 2S communicate them to external amplifier equipment. The Quik-Cap provides a stretchable elastic cap and chinstrap portion capable of comfortably fitting a wide range of head size and shape variability. The Quik-Cap provides a plurality of electrode holders designed to be filled with a conductive electrolyte.. In addition, the Quik-Cap provides a wire harness assembly that -30 can be configured with either carbon or metal lead wires and is capable of interfacing with any type of commercially available amplifier system.
Some specific features and objectives of the invention include the following.
The present invention provides a low cost system for rapidly applying large numbers of electrodes on the head and body that is capable of acquiring signals inside an fMRI system and communicating them outside the shielded environment without the use of any electronic amplification.
It is another objective of the present invention to use carbon lead wires attached to the electrodes positioned on the head and body to limit the susceptibility of the system to contamination from an MRI system and to communicate signals outside a shielded fMRI environment to amplifiers attached to a PC for collecting and processing electrophysiological and other physiologically correlated data.
Another object of the present invention to use metal electrodes composed of Tin, Gold, Silver-Chlorided Silver, or a combination or amalgam of Silver-Chloride powders, each carried in soft rubber electrode mounts and connected to carbon lead wires to limit the susceptibility of the system to physiological and electronically induced contamination.
It is a still further object of the present. invention to use carbon, carbonized plastic, or conductive plastic electrodes in connection with carbon lead wires to further limit the susceptibility of the system to physiological and electronically induced contamination.
It is a still further object of the present invention to use needle electrodes, implantible depth electrodes, or cortical surface electrodes in connection with carbon lead wires to further limit the susceptibility of the system -to physiological and electronically induced contamination while recording signals directly from the brain or spinal chord..
It is a still further object of the present invention that a single electrode, or group of electrodes, may also be used to acquire signals from the eyes, heart or muscles, by providing a mechanism to position electrodes in the appropriate regions of the scalp, face, chest or body.
- Still another object of the present invention is to permit a single lead wire, or group of lead wires, to be used to connect to and communicate signals WO 00/27279 _ PCTIUS99/26459 from external transducer devices used to measure signals related to oxygen uptake, respiration, heart rate, impedance, motion, acceleration, force or other such signals.
Yet another feature of the present invention is to provide separable elastic cap, chinstrap, and wire harness portions to position electrode holders and electrodes on the head, face and body to acquire EEG, EOG, EMG, ECG
and other physiologically correlated signals from humans while inside a magnetic resonance imaging system.
The foregoing and other features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.
Brief Description of the Drawings The objects, features and advantages of the system of the present invention will be apparent from the following description in which:
FIG. 1 is a side view of the elastic cap: and chin" portion of an exemplary embodiment of the present invention showing electrode holders and lead wire harness assembly in which individual lead wires are attached to electrodes (not shown) carried within the electrode holders:.
FIG. 2A is a cross-sectional side view of the electrode holder of FIG.
1. _ FIG. 2B is a top plan view of the embodiment of FIG: 2A.
FIG. 2C is a side plan view of the embodiment of FIG. 2A_ FIG 2D is a top-down view of a rubber O-ring used to attach the electrode holder to the elastic cap portion of FIG. 1.
FIG. 3A is a cross-sectional side view along line A - A of FIG. 3B of an exemplary electrode carried within the electrode holder of FIG. 2A.
FIG. 3B is a top plan view of the embodiment of FIG. 3A.
FIG. 3C is a side plan-view of the embodiment of FIG. 3A.
The present invention provides a low cost system for rapidly applying large numbers of electrodes on the head and body that is capable of acquiring signals inside an fMRI system and communicating them outside the shielded environment without the use of any electronic amplification.
It is another objective of the present invention to use carbon lead wires attached to the electrodes positioned on the head and body to limit the susceptibility of the system to contamination from an MRI system and to communicate signals outside a shielded fMRI environment to amplifiers attached to a PC for collecting and processing electrophysiological and other physiologically correlated data.
Another object of the present invention to use metal electrodes composed of Tin, Gold, Silver-Chlorided Silver, or a combination or amalgam of Silver-Chloride powders, each carried in soft rubber electrode mounts and connected to carbon lead wires to limit the susceptibility of the system to physiological and electronically induced contamination.
It is a still further object of the present. invention to use carbon, carbonized plastic, or conductive plastic electrodes in connection with carbon lead wires to further limit the susceptibility of the system to physiological and electronically induced contamination.
It is a still further object of the present invention to use needle electrodes, implantible depth electrodes, or cortical surface electrodes in connection with carbon lead wires to further limit the susceptibility of the system -to physiological and electronically induced contamination while recording signals directly from the brain or spinal chord..
It is a still further object of the present invention that a single electrode, or group of electrodes, may also be used to acquire signals from the eyes, heart or muscles, by providing a mechanism to position electrodes in the appropriate regions of the scalp, face, chest or body.
- Still another object of the present invention is to permit a single lead wire, or group of lead wires, to be used to connect to and communicate signals WO 00/27279 _ PCTIUS99/26459 from external transducer devices used to measure signals related to oxygen uptake, respiration, heart rate, impedance, motion, acceleration, force or other such signals.
Yet another feature of the present invention is to provide separable elastic cap, chinstrap, and wire harness portions to position electrode holders and electrodes on the head, face and body to acquire EEG, EOG, EMG, ECG
and other physiologically correlated signals from humans while inside a magnetic resonance imaging system.
The foregoing and other features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.
Brief Description of the Drawings The objects, features and advantages of the system of the present invention will be apparent from the following description in which:
FIG. 1 is a side view of the elastic cap: and chin" portion of an exemplary embodiment of the present invention showing electrode holders and lead wire harness assembly in which individual lead wires are attached to electrodes (not shown) carried within the electrode holders:.
FIG. 2A is a cross-sectional side view of the electrode holder of FIG.
1. _ FIG. 2B is a top plan view of the embodiment of FIG: 2A.
FIG. 2C is a side plan view of the embodiment of FIG. 2A_ FIG 2D is a top-down view of a rubber O-ring used to attach the electrode holder to the elastic cap portion of FIG. 1.
FIG. 3A is a cross-sectional side view along line A - A of FIG. 3B of an exemplary electrode carried within the electrode holder of FIG. 2A.
FIG. 3B is a top plan view of the embodiment of FIG. 3A.
FIG. 3C is a side plan-view of the embodiment of FIG. 3A.
FIG. 4A is a perspective top view of an alternative embodiment of a cup shaped electrode carried in an exemplary electrode holder of FIG 2A.
FIG. 4B is a perspective bottom view of an alternative embodiment using a cup shaped electrode carried in the electrode holder of FIG 2A.
FIG. 4C is a top-down view of the embodiment of the electrode of FIG. 4A. -FIG. 4D is a side view of the embodiment of the electrode of FIG. 4A.
FIG. 4E is a cross-sectional view of an alternative embodiment of a conductive plastic electrode embodiment carried in the electrode holder of FIG.2A.
FIG. 4F is a top plan view of the embodiment of the electrode in FIG.
4E.
FIG.5A is a top plan view of an alternative embodiment of a conductive plastic electrode embodiment carried in the electrode holder of FIG.2A.
FIG. 5B is a cross-sectional side view along line B - B of the embodiment of the conductive plastic electrode of FIG. 5A.
FIG.5C is a top plan view of an alternative embodiment of a carbon electrode embodiment carried in the electrode holder of FIG. 2A.
FIG. 5D is a cross-sectional side view along line C - C of the embodiment of the carbon electrode of FIG. 5C.
FIG_ 6 is a top plan view of an alternative embodiment of a cortical depth electrode embodiment used with the carbon lead wire harness of the present invention:. -FIG. 7 is a top plan view of an alternative embodiment of a cortical surface grid electrode embodiment used with the carbon lead wire harness of the present invention.
FIG. 8 is a top plan view of an alternative embodiment of a cortical.
surface strip electrode embodiment used with the carbon lead wire harness of the present invention.
Detailed.Descrintion of the Preferred Embodiments WO 00/27279 PCTfUS99126459 As shown in FIG. 1, the fMRI-compatible electrode placement system of the present invention includes an elastic fabric cap portion 10 and chinstrap -portion 11, both composed preferably of a combined Lycra-SpandexTM
material such as Style #: 96175 Black 09000, manufactured by Liberty Fabrics, 13441 Liberty Lane, Gordonsville, VA). Attached to the elastic cap portion 10, is a plurality of electrode holders 20a-n. The designation "n"
means that the number depends on the number of electrodes desired. In typical usage, for example, n may be in the range from 1 to 1024. Also in FIG. 1, a plurality of lead wires 13 of the present invention form a harness -assembly 14. The lead wires may be constructed of any non-ferromagnetic conductive material, but are preferably made of carbon. The lead wires may be wrapped in groups with flexible wrapping material (not shown), and extend, from the electrodes (not shown) carried within the electrode holders 20a-n away from the head, terminating in a connector, such as a CHG-Series 40 pin connector (not shown) manufactured by 3M, Inc. The flexible wrapping (not -shown) is used to ensure the wires will not be allowed to. coil while inside the MM environment. in order to prevent induced heating of the lead wire material.
As shown in FIGS. 2A - 2D, the electrode holder 20 is preferably constructed from a single piece of molded medical grade EPDM rubber, such as compound L-5099. The electrode holder 20, provides a central hole portion 21, which allows access to the central well portion 22, and which passes down to the scalp surface. Electrolyte is injected through the central bole 21 to fill the central well portion 22 creating a bridge to conduct the electrical signal frcim the skin surface to the electrode (not shown), which rests on the ridge portion 23 located within the central well portion 22 of the electrode holder 20. On the side of the electrode holder 20, near the top, a hole 24 exists where a lead wire attachment portion of tip electrode (not shown) extends from the electrode holder. On the outside portion of the electrode holder 20,. an indentation 25 exists in which two 0-rings 26 are used to capture the elastic fabric of the cap 10 from above and below when the electrode holder is pushed through the elastic cap fabric 10.
FIG. 4B is a perspective bottom view of an alternative embodiment using a cup shaped electrode carried in the electrode holder of FIG 2A.
FIG. 4C is a top-down view of the embodiment of the electrode of FIG. 4A. -FIG. 4D is a side view of the embodiment of the electrode of FIG. 4A.
FIG. 4E is a cross-sectional view of an alternative embodiment of a conductive plastic electrode embodiment carried in the electrode holder of FIG.2A.
FIG. 4F is a top plan view of the embodiment of the electrode in FIG.
4E.
FIG.5A is a top plan view of an alternative embodiment of a conductive plastic electrode embodiment carried in the electrode holder of FIG.2A.
FIG. 5B is a cross-sectional side view along line B - B of the embodiment of the conductive plastic electrode of FIG. 5A.
FIG.5C is a top plan view of an alternative embodiment of a carbon electrode embodiment carried in the electrode holder of FIG. 2A.
FIG. 5D is a cross-sectional side view along line C - C of the embodiment of the carbon electrode of FIG. 5C.
FIG_ 6 is a top plan view of an alternative embodiment of a cortical depth electrode embodiment used with the carbon lead wire harness of the present invention:. -FIG. 7 is a top plan view of an alternative embodiment of a cortical surface grid electrode embodiment used with the carbon lead wire harness of the present invention.
FIG. 8 is a top plan view of an alternative embodiment of a cortical.
surface strip electrode embodiment used with the carbon lead wire harness of the present invention.
Detailed.Descrintion of the Preferred Embodiments WO 00/27279 PCTfUS99126459 As shown in FIG. 1, the fMRI-compatible electrode placement system of the present invention includes an elastic fabric cap portion 10 and chinstrap -portion 11, both composed preferably of a combined Lycra-SpandexTM
material such as Style #: 96175 Black 09000, manufactured by Liberty Fabrics, 13441 Liberty Lane, Gordonsville, VA). Attached to the elastic cap portion 10, is a plurality of electrode holders 20a-n. The designation "n"
means that the number depends on the number of electrodes desired. In typical usage, for example, n may be in the range from 1 to 1024. Also in FIG. 1, a plurality of lead wires 13 of the present invention form a harness -assembly 14. The lead wires may be constructed of any non-ferromagnetic conductive material, but are preferably made of carbon. The lead wires may be wrapped in groups with flexible wrapping material (not shown), and extend, from the electrodes (not shown) carried within the electrode holders 20a-n away from the head, terminating in a connector, such as a CHG-Series 40 pin connector (not shown) manufactured by 3M, Inc. The flexible wrapping (not -shown) is used to ensure the wires will not be allowed to. coil while inside the MM environment. in order to prevent induced heating of the lead wire material.
As shown in FIGS. 2A - 2D, the electrode holder 20 is preferably constructed from a single piece of molded medical grade EPDM rubber, such as compound L-5099. The electrode holder 20, provides a central hole portion 21, which allows access to the central well portion 22, and which passes down to the scalp surface. Electrolyte is injected through the central bole 21 to fill the central well portion 22 creating a bridge to conduct the electrical signal frcim the skin surface to the electrode (not shown), which rests on the ridge portion 23 located within the central well portion 22 of the electrode holder 20. On the side of the electrode holder 20, near the top, a hole 24 exists where a lead wire attachment portion of tip electrode (not shown) extends from the electrode holder. On the outside portion of the electrode holder 20,. an indentation 25 exists in which two 0-rings 26 are used to capture the elastic fabric of the cap 10 from above and below when the electrode holder is pushed through the elastic cap fabric 10.
As shown in FIGS. 3A - 3C, the electrode 30 of the present invention has a flat disk portion 31 with a central hole 32. The electrode 30 also includes--a lead wire attachment portion 33, which extends outward from the flat disk portion 31 and provides a pathway 34. Such a pathway may be created by drilling or by other mechanisms. The drilled pathway 34 provides an opening in which the lead wire 13 passes and is attached to the electrode by crimping the attachment portion 33 onto the lead wire 13.
In a typical assembly sequence, an 0 ring is slipped over the lead wire 13. The electrode 30 is inserted into the. central well portion 22 of the electrode holder 20 and rests on the ridge portion 23 to ensure correct placement. The electrode holder is inserted through a button hole or other opening in the .elastic fabric cap and secured by positioning one or more 0-rings over the fabric. The lead wire 13 is placed into the pathway .34 and the attachment portion 33 is crimped onto the lead wire-An' alternative embodiment of the preferred electrode of the present invention is shown in FIGS. 4A - 4F, where typical cup shaped electrodes 40 may be composed of metal- (such as those manufactured by Specialized Laboratory Equipment, 232 Selsdon Rd.- South Croydon Surrey, UK, PN:
B0196/02) or conductive plastic 41 (such as those manufactured by Plastics One, 6591 Merriman Rd., S.W., Roanoke, VA, PN: 36562). In a typical metal -electrode, a central hole 43 exists to allow injection of electrolyte down to the skin surface: In additiom a well portion 44 is provided to hold electrolyte in contact with the electrode surface. In a typical conductive plastic electrode 41, a central hole 45 exists to allow injection of electrolyte down to the skin surface- Again, a well portion 46 is provided to hold electrolyte in contact with the electrode surface. Both types of electrodes 40 and 41, may be readily carried within the electrode holder 20 of the present invention An alternative embodiment of the preferred electrode of the present invention is shown in FIGS. 5A - 5D, where conductive plastic electrodes 50 (such as those manufactured by Select-Engineering Inc., 260 Lunenburg St., .Fitchburg. MA, PN: SRT-3001/LP/0.06) and carbon electrodes 51- (such as those manufactured by Select Engineering Inc., 260 Lunenburg St., Fitchburg, CA 02354549 2001-05-10 j641 0 NOY 2000 MA, PN: SRT-2001/CF/40) are shown. In both cases the non-metallic nature of the electrode material makes them less susceptible to induced currents present in the MRI environment, as well as to other physiological artifacts caused by movement of the body within the MRI device. On the conductive S plastic electrode 50, a lead wire attachment means 52 exists, which provides a surface where conductive epoxy (such as EPO-TEK E2101) is used to attach the carbon lead wire 13 to the conductive plastic electrode 50. On the carbon electrode 51, a well portion 53 exists to hold electrolyte in contact with the electrode surface. The lead wire 13 is attached to the carbon electrode 51 by use of conductive epoxy at the electrode attachment point 54. Both the conductive plastic electrode 50 and carbon electrode 51 may be carried within electrode holder 20 of the present invention.
An alternative embodiment of the preferred electrode of the present invention is shown in FIG. 6, where an implantible depth electrode assembly 415 60 (such as those manufactured by AD-Tech Medical Instrument Corp., 1901 William St., Racine, WI, PN: SP-10P) is used. The depth electrode assembly 60 of the present embodiment positions 10 discreet electrodes 61a-j in which each acquires signals from a different region of the brain. The depth electrode assembly 60 can be placed into the cortex of a patient to collect electrical 2signals from multiple deep regions of the brain simultaneously. The depth electrode assembly 60 would not be carried in the electrode holderAl of the present invention but rather the lead wire harness assembly 14 directly interfaces to the depth electrode assembly Connection System 62.
An alternative embodiment of the preferred electrode of the present 25 invention is shown in FIG. 7, where a subdural cortical surface electrode assembly 70 (such as those manufactured by AD-Tech Medical Instrument Corp., 1901 William St. Racine, WI, PN: T-WS-20) is used. In the example given, the subdural cortical surface electrode assembly 70 of the present embodiment positions 20 discreet electrodes 71 a-t in a grid pattern in which 30 each acquires signals from a different region of the brain. However, other subdural cortical surface electrode assemblies exist that provide different numbers'of electrodes. Grids with up to 128 discreet electrodes (not shown) QED SHEET
CA 02354549 2001-05-10 ,Tt v -Lodi are readily available commercially, but other numbers of electrodes may be used. The subdural cortical surface electrode assembly 70 can be placed on the cortex of a patient to collect electrical signals from multiple regions of the brain underlying the grid pattern formed by the electrodes of the assembly.
The subdural cortical surface electrode assembly 70 would not be carried in ZO
the electrode holder B' of the present but rather the lead wire harness assembly 14 would be directly connected to the subdural cortical surface electrode assembly Connection System 72.
An alternative embodiment of the preferred electrode of the present invention is shown in FIG. 8, where a subdural cortical surface electrode assembly 80 (such as that manufactured by AD-Tech Medical Instrument Corp., 1901 William St., Racine, WI, PN: T-WS-8) is used. The subdural cortical surface electrode assembly 80 of the present embodiment positions 8 discreet electrodes 81 a-h in a strip pattern in which each acquires signals from a different region of the brain. However, other subdural cortical surface electrode assemblies are readily available commercially that provide from 1 up to 128 discreet electrodes (not shown). The subdural cortical surface electrode assembly 80 can be placed on the cortex of a patient to collect electrical signals from multiple regions of the brain underlying the strip pattern formed by the electrodes of the assent ly. The subdural cortical surface electrode assembly 80 would not be carried in the electrode holderWof the present invention but would be directly connected to the lead wire harness assembly 14 through the assembly Connection System 82..
In operation, the assembled Quik-Cap is placed on the patient's head and then, in appropriate embodiments, each electrode holder is filled with conductive electrolyte. Slight abrasion of the skin may be required during placement to reduce the impedance at the skin electrolyte interface to acceptable levels as determined by the input characteristics of the amplifier system to which the Quik-Cap assembly is attached.
In the manner described, the problems associated with collection of patient data in the environment of an MRI can be overcome.
In this disclosure, there is shown and described only the preferred embodiments of the invention, but as mentioned above, one should understand that the" invention is capable of use in various other combinations and environments and is capable of changes or modifications within the scope of the inventive concepts as expressed herein.
In a typical assembly sequence, an 0 ring is slipped over the lead wire 13. The electrode 30 is inserted into the. central well portion 22 of the electrode holder 20 and rests on the ridge portion 23 to ensure correct placement. The electrode holder is inserted through a button hole or other opening in the .elastic fabric cap and secured by positioning one or more 0-rings over the fabric. The lead wire 13 is placed into the pathway .34 and the attachment portion 33 is crimped onto the lead wire-An' alternative embodiment of the preferred electrode of the present invention is shown in FIGS. 4A - 4F, where typical cup shaped electrodes 40 may be composed of metal- (such as those manufactured by Specialized Laboratory Equipment, 232 Selsdon Rd.- South Croydon Surrey, UK, PN:
B0196/02) or conductive plastic 41 (such as those manufactured by Plastics One, 6591 Merriman Rd., S.W., Roanoke, VA, PN: 36562). In a typical metal -electrode, a central hole 43 exists to allow injection of electrolyte down to the skin surface: In additiom a well portion 44 is provided to hold electrolyte in contact with the electrode surface. In a typical conductive plastic electrode 41, a central hole 45 exists to allow injection of electrolyte down to the skin surface- Again, a well portion 46 is provided to hold electrolyte in contact with the electrode surface. Both types of electrodes 40 and 41, may be readily carried within the electrode holder 20 of the present invention An alternative embodiment of the preferred electrode of the present invention is shown in FIGS. 5A - 5D, where conductive plastic electrodes 50 (such as those manufactured by Select-Engineering Inc., 260 Lunenburg St., .Fitchburg. MA, PN: SRT-3001/LP/0.06) and carbon electrodes 51- (such as those manufactured by Select Engineering Inc., 260 Lunenburg St., Fitchburg, CA 02354549 2001-05-10 j641 0 NOY 2000 MA, PN: SRT-2001/CF/40) are shown. In both cases the non-metallic nature of the electrode material makes them less susceptible to induced currents present in the MRI environment, as well as to other physiological artifacts caused by movement of the body within the MRI device. On the conductive S plastic electrode 50, a lead wire attachment means 52 exists, which provides a surface where conductive epoxy (such as EPO-TEK E2101) is used to attach the carbon lead wire 13 to the conductive plastic electrode 50. On the carbon electrode 51, a well portion 53 exists to hold electrolyte in contact with the electrode surface. The lead wire 13 is attached to the carbon electrode 51 by use of conductive epoxy at the electrode attachment point 54. Both the conductive plastic electrode 50 and carbon electrode 51 may be carried within electrode holder 20 of the present invention.
An alternative embodiment of the preferred electrode of the present invention is shown in FIG. 6, where an implantible depth electrode assembly 415 60 (such as those manufactured by AD-Tech Medical Instrument Corp., 1901 William St., Racine, WI, PN: SP-10P) is used. The depth electrode assembly 60 of the present embodiment positions 10 discreet electrodes 61a-j in which each acquires signals from a different region of the brain. The depth electrode assembly 60 can be placed into the cortex of a patient to collect electrical 2signals from multiple deep regions of the brain simultaneously. The depth electrode assembly 60 would not be carried in the electrode holderAl of the present invention but rather the lead wire harness assembly 14 directly interfaces to the depth electrode assembly Connection System 62.
An alternative embodiment of the preferred electrode of the present 25 invention is shown in FIG. 7, where a subdural cortical surface electrode assembly 70 (such as those manufactured by AD-Tech Medical Instrument Corp., 1901 William St. Racine, WI, PN: T-WS-20) is used. In the example given, the subdural cortical surface electrode assembly 70 of the present embodiment positions 20 discreet electrodes 71 a-t in a grid pattern in which 30 each acquires signals from a different region of the brain. However, other subdural cortical surface electrode assemblies exist that provide different numbers'of electrodes. Grids with up to 128 discreet electrodes (not shown) QED SHEET
CA 02354549 2001-05-10 ,Tt v -Lodi are readily available commercially, but other numbers of electrodes may be used. The subdural cortical surface electrode assembly 70 can be placed on the cortex of a patient to collect electrical signals from multiple regions of the brain underlying the grid pattern formed by the electrodes of the assembly.
The subdural cortical surface electrode assembly 70 would not be carried in ZO
the electrode holder B' of the present but rather the lead wire harness assembly 14 would be directly connected to the subdural cortical surface electrode assembly Connection System 72.
An alternative embodiment of the preferred electrode of the present invention is shown in FIG. 8, where a subdural cortical surface electrode assembly 80 (such as that manufactured by AD-Tech Medical Instrument Corp., 1901 William St., Racine, WI, PN: T-WS-8) is used. The subdural cortical surface electrode assembly 80 of the present embodiment positions 8 discreet electrodes 81 a-h in a strip pattern in which each acquires signals from a different region of the brain. However, other subdural cortical surface electrode assemblies are readily available commercially that provide from 1 up to 128 discreet electrodes (not shown). The subdural cortical surface electrode assembly 80 can be placed on the cortex of a patient to collect electrical signals from multiple regions of the brain underlying the strip pattern formed by the electrodes of the assent ly. The subdural cortical surface electrode assembly 80 would not be carried in the electrode holderWof the present invention but would be directly connected to the lead wire harness assembly 14 through the assembly Connection System 82..
In operation, the assembled Quik-Cap is placed on the patient's head and then, in appropriate embodiments, each electrode holder is filled with conductive electrolyte. Slight abrasion of the skin may be required during placement to reduce the impedance at the skin electrolyte interface to acceptable levels as determined by the input characteristics of the amplifier system to which the Quik-Cap assembly is attached.
In the manner described, the problems associated with collection of patient data in the environment of an MRI can be overcome.
In this disclosure, there is shown and described only the preferred embodiments of the invention, but as mentioned above, one should understand that the" invention is capable of use in various other combinations and environments and is capable of changes or modifications within the scope of the inventive concepts as expressed herein.
Claims (21)
1. An apparatus for collecting un-amplified physiological electrical signals inside of a shielded environment of a functional magnetic resonance imaging (MRI) system during normal operation of the functional MRI system and conducting such signals outside the shielded environment for amplification, the apparatus comprising:
a plurality of electrodes; and a plurality of electrode lead wires connected between said electrodes and amplifier equipment external to the shielded environment of said functional MRI system, said electrode lead wires communicating said electrical signals from said electrodes to said amplifier equipment;
wherein the electrode lead wires are enclosed by a wrapping material that prevents the lead wires from coiling into a loop, whereby induced heating in the lead wires is inhibited when placed in a magnetic field in the functional MRI system.
a plurality of electrodes; and a plurality of electrode lead wires connected between said electrodes and amplifier equipment external to the shielded environment of said functional MRI system, said electrode lead wires communicating said electrical signals from said electrodes to said amplifier equipment;
wherein the electrode lead wires are enclosed by a wrapping material that prevents the lead wires from coiling into a loop, whereby induced heating in the lead wires is inhibited when placed in a magnetic field in the functional MRI system.
2. The apparatus of claim 1, wherein the electrodes, are manufactured from a material selected from the group consisting of: silver, tin, gold, carbon, platinum, iridium, silver/silver chloride, conductive plastic, carbonized plastic and carbon fibers.
3. The apparatus of claim 1, wherein the electrodes are subdermal needles, subdural cortical surface electrodes, or subdural depth electrodes.
4. The apparatus of claim 1 wherein the electrode lead wires are manufactured from a material selected from the group consisting of: silver, tin, gold, carbon, platinum, iridium, silver/silver chloride, conductive plastic, carbonized plastic and carbon fibers.
5. The apparatus of claim 1, wherein the electrode lead wires conduct signals over a distance of more than 10 feet.
6. The apparatus of claim 1, wherein each of said electrodes is positioned within an electrode holder.
7. The apparatus of claim 6, wherein the electrode holder contains an opening through which electroyte can be applied to a patient.
8. The apparatus of claim 7 wherein the electrode holder is configured to accommodate one or more O-rings,
9. The apparatus of any one of claims 6 to 8, wherein the electrode holder is made of a flexible material.
10. The apparatus of any one of claims 6 to 8, wherein the electrode holder is made of rubber.
11. The apparatus of any one of claims 6 to 10, wherein each said electrode holder is mounted to an elastic cap for placement on a patient's head.
12. An apparatus for collecting un-amplified physiological electrical signals during normal operation of a Magnetoencephalography (MEG) system and conducting such signals outside of the shielded environment of the MEG system for amplification, the apparatus comprising:
a plurality of electrodes; and a plurality of electrode lead wires connected between said electrodes and amplifier equipment external to the shielded environment of said MEG system, said electrode, lead wires communicating said electrical signals from said electrodes to said amplifier equipment;
wherein the electrode lead wires are enclosed by a wrapping material that prevents the lead wires from coiling into a loop, whereby induced heating in the lead wires is inhibited when placed in a magnetic field in the MEG system.
a plurality of electrodes; and a plurality of electrode lead wires connected between said electrodes and amplifier equipment external to the shielded environment of said MEG system, said electrode, lead wires communicating said electrical signals from said electrodes to said amplifier equipment;
wherein the electrode lead wires are enclosed by a wrapping material that prevents the lead wires from coiling into a loop, whereby induced heating in the lead wires is inhibited when placed in a magnetic field in the MEG system.
13. A transducer lead assembly comprising a plurality of connection lead wires for conducting un-amplified electrical signals outside a shielded environment of a functional magnetic resonance imaging (MRI) system for amplification: wherein the electrode lead wires are enclosed by a wrapping material that prevents the lead wires from coiling into a loop, whereby induced heating in the lead wires is inhibited when placed in a magnetic field in the functional MRI system.
14. The transducer lead assembly of claim 13 wherein at least one of said plurality of connection lead wires is configured to carry un-amplified electrical signals selected from the group comprising: EOG signals, EMG signals, ECG signals, and signals to or from transducers for measuring impedance, skin conductance, acceleration, motion, or respiration.
15. A method of collecting electrical data from a plurality of electrodes in dermal contact with a patient located inside of a shielded environment of a functional magnetic resonance imaging (MRI) system during normal operation of the functional MRI system, the method comprising the steps of:
connecting each of said electrodes to one end of a lead wire selected from a plurality of lead wires;
connecting a second end of each of said lead wires to an amplifier system located outside of said shielded environment; and enclosing each of said plurality of lead wires by a wrapping material that prevents the lead wires from coiling into a loop, whereby induced heating in the lead wires is inhibited when placed in a magnetic field in the functional MRI system
connecting each of said electrodes to one end of a lead wire selected from a plurality of lead wires;
connecting a second end of each of said lead wires to an amplifier system located outside of said shielded environment; and enclosing each of said plurality of lead wires by a wrapping material that prevents the lead wires from coiling into a loop, whereby induced heating in the lead wires is inhibited when placed in a magnetic field in the functional MRI system
16. The method of claim 15, wherein said electrodes are made from a non-ferromagnetic material.
17. The method of claim 15, wherein said lead wires are made from a non-ferromagnetic material.
18. The method of claim 16 or 17 wherein said non-ferromagnetic material is one of the group consisting of silver, tin, gold, carbon, platinum, iridium, silver/silver chloride, conductive plastic, carbonized plastic and carbon fibers.
19. The method of any one of claims 15 to 18, further comprising the steps of:
mounting one or more electrode holders in a flexible cap; and inserting said electrodes into said electrode holders.
mounting one or more electrode holders in a flexible cap; and inserting said electrodes into said electrode holders.
20. The method of claim 19, further comprising the step of securing said flexible cap to the head of said patient using a strap.
21. The method of claim 20, further comprising the step of adjusting the length of the strap connection. between the strap and the cap.
using at least one Velcro
using at least one Velcro
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US10791898P | 1998-11-10 | 1998-11-10 | |
| US60/107,918 | 1998-11-10 | ||
| PCT/US1999/026459 WO2000027279A1 (en) | 1998-11-10 | 1999-11-10 | fMRI COMPATIBLE ELECTRODE AND ELECTRODE PLACEMENT TECHNIQUES |
Publications (2)
| Publication Number | Publication Date |
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| CA2354549A1 CA2354549A1 (en) | 2000-05-18 |
| CA2354549C true CA2354549C (en) | 2013-01-08 |
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|---|---|---|---|
| CA2354549A Expired - Fee Related CA2354549C (en) | 1998-11-10 | 1999-11-10 | Fmri compatible electrode and electrode placement techniques |
Country Status (5)
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| EP (1) | EP1128764A4 (en) |
| JP (1) | JP4805456B2 (en) |
| AU (1) | AU1613400A (en) |
| CA (1) | CA2354549C (en) |
| WO (1) | WO2000027279A1 (en) |
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| GB2370776B (en) * | 2000-09-13 | 2004-10-13 | Neoventa Medical Ab | Fetal scalp electrode |
| EP1273922B1 (en) * | 2001-07-06 | 2007-05-23 | Max-Planck-Gesellschaft zur Förderung der Wissenschaften e.V. | Methods and devices for measuring electrical currents |
| FI119172B (en) | 2003-11-18 | 2008-08-29 | Nexstim Oy | Electrode construction for measuring electrical responses from a human body |
| US9155877B2 (en) | 2004-03-30 | 2015-10-13 | Medtronic, Inc. | Lead electrode for use in an MRI-safe implantable medical device |
| US8989840B2 (en) | 2004-03-30 | 2015-03-24 | Medtronic, Inc. | Lead electrode for use in an MRI-safe implantable medical device |
| US7174219B2 (en) | 2004-03-30 | 2007-02-06 | Medtronic, Inc. | Lead electrode for use in an MRI-safe implantable medical device |
| US7844344B2 (en) | 2004-03-30 | 2010-11-30 | Medtronic, Inc. | MRI-safe implantable lead |
| US7561915B1 (en) | 2004-12-17 | 2009-07-14 | Cardiac Pacemakers, Inc. | MRI system having implantable device safety features |
| US8014867B2 (en) | 2004-12-17 | 2011-09-06 | Cardiac Pacemakers, Inc. | MRI operation modes for implantable medical devices |
| US8280526B2 (en) | 2005-02-01 | 2012-10-02 | Medtronic, Inc. | Extensible implantable medical lead |
| US8825180B2 (en) | 2005-03-31 | 2014-09-02 | Medtronic, Inc. | Medical electrical lead with co-radial multi-conductor coil |
| US9044593B2 (en) | 2007-02-14 | 2015-06-02 | Medtronic, Inc. | Discontinuous conductive filler polymer-matrix composites for electromagnetic shielding |
| US10537730B2 (en) | 2007-02-14 | 2020-01-21 | Medtronic, Inc. | Continuous conductive materials for electromagnetic shielding |
| US8483842B2 (en) | 2007-04-25 | 2013-07-09 | Medtronic, Inc. | Lead or lead extension having a conductive body and conductive body contact |
| US8086321B2 (en) | 2007-12-06 | 2011-12-27 | Cardiac Pacemakers, Inc. | Selectively connecting the tip electrode during therapy for MRI shielding |
| US8032228B2 (en) | 2007-12-06 | 2011-10-04 | Cardiac Pacemakers, Inc. | Method and apparatus for disconnecting the tip electrode during MRI |
| US8311637B2 (en) | 2008-02-11 | 2012-11-13 | Cardiac Pacemakers, Inc. | Magnetic core flux canceling of ferrites in MRI |
| US8160717B2 (en) | 2008-02-19 | 2012-04-17 | Cardiac Pacemakers, Inc. | Model reference identification and cancellation of magnetically-induced voltages in a gradient magnetic field |
| US9037263B2 (en) | 2008-03-12 | 2015-05-19 | Medtronic, Inc. | System and method for implantable medical device lead shielding |
| US20110208084A1 (en) * | 2008-09-09 | 2011-08-25 | Fernando Seoane Martinez | Method and apparatus for brain damage detection |
| US8571661B2 (en) | 2008-10-02 | 2013-10-29 | Cardiac Pacemakers, Inc. | Implantable medical device responsive to MRI induced capture threshold changes |
| EP2398553B1 (en) | 2009-02-19 | 2015-07-22 | Cardiac Pacemakers, Inc. | Systems for providing arrhythmia therapy in mri environments |
| JP5306886B2 (en) * | 2009-04-14 | 2013-10-02 | 独立行政法人国立高等専門学校機構 | Bioelectric signal measuring sensor and manufacturing method thereof |
| US10035014B2 (en) | 2009-04-30 | 2018-07-31 | Medtronic, Inc. | Steering an implantable medical lead via a rotational coupling to a stylet |
| JP5558583B2 (en) | 2009-12-08 | 2014-07-23 | カーディアック ペースメイカーズ， インコーポレイテッド | Implantable medical device including automatic tachycardia detection and control in an MRI environment |
| EP2561806B1 (en) * | 2010-04-21 | 2019-06-12 | Tohoku University | Electroencephalogram electrode unit for small animals and measurement system using same |
| US9463317B2 (en) | 2012-04-19 | 2016-10-11 | Medtronic, Inc. | Paired medical lead bodies with braided conductive shields having different physical parameter values |
| CN102727194B (en) * | 2012-05-04 | 2014-01-22 | 燕山大学 | Electroencephalogram electrode space positioning system and positioning method |
| US9993638B2 (en) | 2013-12-14 | 2018-06-12 | Medtronic, Inc. | Devices, systems and methods to reduce coupling of a shield and a conductor within an implantable medical lead |
| WO2015170662A1 (en) * | 2014-05-09 | 2015-11-12 | アルプス電気株式会社 | Human body characteristic detection device and glasses-type electronic device |
| EP3171931B1 (en) | 2014-07-23 | 2021-11-10 | Medtronic, Inc. | Methods of shielding implantable medical leads and implantable medical lead extensions |
| EP3191175B1 (en) | 2014-07-24 | 2022-03-02 | Medtronic, Inc. | Apparatus for shielding implantable medical leads and lead extensions |
| CN107495964A (en) * | 2017-09-15 | 2017-12-22 | 西安富德医疗电子有限公司 | Disposable medical spiral pin electrode |
| KR102124430B1 (en) * | 2018-07-16 | 2020-06-18 | 고려대학교 산학협력단 | Method for selecting optimized eeg electrodes based on brain machine interfaces and recording medium for performing the method |
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| US3993048A (en) * | 1972-09-08 | 1976-11-23 | Biomedical International Company | Biomedical electrode |
| US4936306A (en) * | 1985-02-15 | 1990-06-26 | Doty James R | Device and method for monitoring evoked potentials and electroencephalograms |
| AT398274B (en) * | 1990-03-22 | 1994-11-25 | Buertlmair Hermann | ELECTRODE FOR ELECTRICAL MEASURING DEVICES AND THE LIKE |
| US5044368A (en) * | 1990-04-23 | 1991-09-03 | Ad-Tech Medical Instrument Corporation | Diagnostic electrode for use with magnetic resonance imaging |
| US5217010A (en) * | 1991-05-28 | 1993-06-08 | The Johns Hopkins University | Ecg amplifier and cardiac pacemaker for use during magnetic resonance imaging |
| AU667199B2 (en) * | 1991-11-08 | 1996-03-14 | Physiometrix, Inc. | EEG headpiece with disposable electrodes and apparatus and system and method for use therewith |
| US5445162A (en) * | 1993-08-27 | 1995-08-29 | Beth Israel Hospital Association | Apparatus and method for recording an electroencephalogram during magnetic resonance imaging |
| US5411545A (en) * | 1994-03-14 | 1995-05-02 | Medtronic, Inc. | Medical electrical lead |
| JP3227593B2 (en) * | 1994-09-22 | 2001-11-12 | 日本光電工業株式会社 | Multi sensor |
| US5779651A (en) * | 1997-02-07 | 1998-07-14 | Bio Syntech | Medical apparatus for the diagnosis of cartilage degeneration via spatial mapping of compression-induced electrical potentials |
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- 1999-11-10 EP EP99958852A patent/EP1128764A4/en not_active Ceased
- 1999-11-10 CA CA2354549A patent/CA2354549C/en not_active Expired - Fee Related
- 1999-11-10 WO PCT/US1999/026459 patent/WO2000027279A1/en active Application Filing
- 1999-11-10 JP JP2000580517A patent/JP4805456B2/en not_active Expired - Lifetime
- 1999-11-10 AU AU16134/00A patent/AU1613400A/en not_active Abandoned
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| WO2000027279A1 (en) | 2000-05-18 |
| AU1613400A (en) | 2000-05-29 |
| CA2354549A1 (en) | 2000-05-18 |
| JP2002529132A (en) | 2002-09-10 |
| EP1128764A1 (en) | 2001-09-05 |
| EP1128764A4 (en) | 2003-06-04 |
| JP4805456B2 (en) | 2011-11-02 |
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| EEER | Examination request | ||
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