A medical appliance for use in magnetic resonance imaging procedures. A guidewire for vascular procedures is formed by a coaxial cable acting as antenna in a magnetic resonance imaging system.
|
0. 55. A method of generating an image of a wall of a body cavity in a patient, the method comprising:
inserting a magnetic resonance imaging (mri) open wire length antenna into the body cavity, the antenna including an open conductor length comprising at least one open ended conductive element;
passing the mri open wire length antenna through the body cavity to a site to be imaged; and
obtaining an mri image of the body cavity wall proximate the antenna.
0. 40. A method of generating an image of a wall of a body cavity in a patient, the method comprising:
inserting an open wire length antenna including an open conductor length into the cavity, where the open conductor length includes at least one open ended conductive element;
generating a magnetic field gradient and electromagnetic (EM) radiation external from the patient and transmitting the gradient and EM radiation into the patient;
transmitting a response signal, based on a detected resonant response from a region of the patient closely proximate the antenna, to a magnetic resonance imaging (mri) processor;
receiving the response signal at the mri processor; and
obtaining an image of the cavity wall proximate the antenna based on the response signal.
0. 53. A medical apparatus for imaging a body cavity wall of a body cavity in a patient by interacting with a magnetic resonanse imaging (mri) system which generates a magnetic field gradient and electromagnetic (EM) radiation external from the patient and transmits the gradient and EM radiation into the patient and receives a response signal indicative of a resonant response from the patient, the apparatus comprising:
an mri open wire length antenna configured to be inserted into the body cavity and passed along the body cavity to a site to be imaged and to provide the response signal, based on the resonant response from a region of the patient closely proximate the antenna, to the mri system, the antenna including an open conductor length comprising at least one open ended conductive element.
0. 49. A method of generating an image of a blood vessel wall of a blood vessel in a patient, the method comprising:
inserting an open wire length antenna including an open conductor length into the blood vessel, where the open conductor length includes at least one open ended conductive element;
passing the antenna through the blood vessel to a site to be imaged;
generating a magnetic field gradient and electromagnetic (EM) radiation external from the patient and transmitting the gradient and EM radiation into the patient;
transmitting a response signal, based on a detected resonant response from a region of the patient closely proximate the antenna, to a magnetic resonance imaging (mri) processor;
receiving the response signal at the mri processor;
and obtaining an image of the blood vessel wall proximate the antenna based on the response signal.
0. 28. A medical apparatus for imaging a wall of a body cavity in a patient by interacting with a magnetic resonance imaging (mri) system which generates a magnetic field gradient and electromagnetic (EM) radiation externally from the patient and transmits the gradient and EM radiation into the patient and receives a response signal indicative of a resonant response from the patient, the apparatus comprising:
an open wire length antenna including an open conductor length configured to be inserted into the cavity and provide the response signal, based on the resonant response from a region of the patient closely proximate the antenna, to the mri system, where the open conductor length includes at least one open ended conductive element; and
a controller coupled to the antenna and configured to receive the response signal to obtain an image of the cavity wall proximate the antenna.
0. 64. A medical apparatus for imaging a wall of a body cavity in a patient by interacting with a magnetic resonance imaging (mri) system which generates a magnetic field gradient and electromagnetic (EM) radiation and transmits the gradient and EM radiation into the patient and receives a response signal indicative of a resonant response from the patient, the apparatus comprising:
an antenna including an open conductor length configured to be inserted into the cavity and provide the response signal, based on the resonant response from a region of the patient closely proximate the antenna, to the mri system wherein the antenna includes a first elongate conductor having a portion thereof forming the open conductor length, and a second elongate conductor, the first and second elongate conductors extending to a proximal end of the antenna; and
a controller coupled to the antenna and configured to receive the response signal to obtain an image of the cavity wall proximate the antenna.
0. 50. A medical apparatus for imaging a blood vessel wall of a blood vessel in a patient by interacting with a magnetic resonance imaging (mri) system which generates a magnetic field gradient and electromagnetic (EM) radiation external from the patient and transmits the gradient and EM radiation into the patient and receives a response signal indicative of a resonant response from the patient, the apparatus comprising:
an open wire length antenna configured to be inserted into the blood vessel and passed along the blood vessel to a site to be imaged and to provide the response signal, based on the resonant response from a region of the patient closely proximate the antenna, to the mri system, the antenna including an open conductor length comprising at least one open ended conductive element; and
a controller coupled to the antenna and configured to receive the response signal and repeatedly calculate antenna location to obtain an image of the blood vessel wall proximate the antenna.
20. A medical appliance comprising an elongated and signal-receiving antenna for detecting and providing magnetic resonance response signals, the antenna adapted to be inserted into the body during magnetic resonance imaging procedures and for providing the response signals used for calculating a position of the medical appliance in the body, wherein the antenna comprises an open wire length including first and second conductors having proximal ends adapted and arranged for interconnection to a receiver to couple the detected resonance response signals to the receiver, spaced-apart distal ends, and at least a first insulator for physically separating and electrically insulating adjacent portions of the first and second conductors, the distal ends of the first and second conductors and the at least first insulator adapted and arranged for exposure to a field of electromagnetic energy during a magnetic resonance procedure to couple electromagnetic energy from the field into the antenna and detect and provide the magnetic resonance response signals to the distal ends of the conductors.
1. A medical appliance comprising an elongated signal-receiving antenna for detecting and providing magnetic resonance response signals, the antennas adapted to be inserted into the body during magnetic resonance imaging procedures and for providing the response signals used for calculating a position of the medical appliance in the body, wherein the antenna comprises an open wire length including first and second conductor means having proximal ends adapted and arranged for interconnection to a receiver to couple the detected resonance response signals to the receiver, spaced-part distal ends, and at least a first insulator means for physically separating and electrically insulating adjacent portions of the first and second conductor means, the distal ends of the first and second conductor means and the at least first insulator means adapted and arranged for exposure to a field of electromagnetic energy during a magnetic resonance procedure to couple electromagnetic energy from the field into the antenna and detect and provide the magnetic resonance response signals to the proximal ends of the conductor means.
13. A medical appliance antenna system for use in connection with magnetic resonance imaging procedures, including:
a medical appliance comprising an elongated signal-receiving antenna for detecting and providing magnetic resonance response signals, the antenna adapted to be inserted into the body during magnetic resonance imaging procedures and for providing the response signals used for calculating a position of the medical appliance in the body, wherein the antenna includes an open wire length including first and second conductors having proximal ends adapted and arranged for interconnection to a receiver to couple the detected response signals to the receiver, spaced-apart distal ends, and at least a first insulator for physically separating and electrically insulating adjacent portions of the first and second conductors, the distal ends of the first and second conductors and the at least first insulator adapted and arranged for exposure to a field of electromagnetic energy during a magnetic resonance procedure to couple the electromagnetic energy from the field to the antenna and detect and provide the magnetic resonance response signals to the proximal ends of the conductors; and
a receiver electrically connected to the antenna for receiving the magnetic resonance response signals and providing information representative of the position of the medical appliance.
2. A medical appliance according to
3. A medical appliance according to
4. A medical appliance according to
5. A medical appliance according to
6. A medical appliance according to
7. A medical appliance according to
8. A medical appliance according to
9. A medical appliance according to
10. A medical appliance according to
11. A medical appliance according to
12. A medical appliance according to
14. A medical appliance according to
15. A medical appliance according to
16. A medical appliance according to
17. A medical appliance according to
18. A medical appliance according to
19. A medical appliance according to
21. A medical appliance according to
22. A medical appliance according to
23. A medical appliance according to
24. A medical appliance according to
25. A medical appliance according to
26. A medical appliance according to
27. A medical appliance according to
0. 29. The medical apparatus of
0. 30. The medical apparatus of
0. 31. The medical apparatus of
0. 32. The medical apparatus of
0. 33. The medical apparatus of
0. 34. The medical apparatus of
0. 35. The medical apparatus of
0. 36. The medical apparatus of
0. 37. The medical apparatus of
0. 38. The medical apparatus of
0. 39. The medical apparatus of
0. 41. The method of
repeatedly calculating antenna location.
0. 42. The method of
processing data to obtain an image of the antenna.
0. 43. The method of
calculating antenna position.
0. 44. The method of
calculating antenna orientation.
0. 45. The method of
repeatedly measuring, reconstructing and storing the image to obtain an increased resolution image of the cavity wall.
0. 46. The method of
capacitively coupling the antenna to an EM field generated by the EM radiation to detect the resonant response.
0. 47. The method of
inserting the antenna into the vasculature; and
passing the antenna through the vasculature to a site to be imaged.
0. 48. The method of
positioning a catheter in the vasculature through use of the guidewire.
0. 51. The medical apparatus of
0. 52. The medical apparatus of
0. 54. The medical apparatus of
a controller coupled to the antenna and configured to receive the response signal and repeatedly calculate antenna location to obtain an image of the blood vessel wall proximate the antenna.
0. 56. The method of
generating a magnetic field gradient and electromagnetic (EM) radiation external from the patient and transmitting the gradient and EM radiation into the patient;
transmitting a response signal, based on a detected resonant response from a region of the patient closely proximate the antenna, to an mri processor;
receiving the response signal at the mri processor; and
calculating antenna location based on the response signal.
0. 57. The method of
repeatedly calculating antenna location.
0. 58. The method of
capacitively coupling the antenna to an EM field generated by the EM radiation to detect the resonant response.
0. 59. The method of
processing data to obtain an image of the antenna.
0. 60. The method of
calculating antenna position.
0. 61. The method of
calculating antenna orientation.
0. 62. The method of
repeatedly measuring, reconstructing and storing the image to obtain an increased resolution image of the blood vessel wall.
0. 63. The method of
positioning a catheter in the vasculature through use of the guidewire.
0. 65. The medical apparatus of
0. 66. The medical apparatus of
0. 67. The medical apparatus of
0. 68. The medical apparatus of
|
|||||||||||||||||||||||||||
This application is a continuation of application Ser. No. 08/311,700, filed 23 Sep., 1994, now abandoned.
This invention relates to a medical appliance for use in magnetic resonance imaging procedures performed on a body, comprising an antenna detecting magnetic resonance response signals, the antenna intended to be inserted into the body for interacting with a magnetic resonance procedure for calculating the position of the medical appliance in the body.
Tracking of catheters and other devices positioned within a body may be achieved by means of a magnetic resonance imaging system in order to avoid using X-rays and the risk of accumulated X-ray dose to the patient and long term exposure to the attending medical staff.
Typically, such a magnetic resonance imaging system may be comprised of magnet means, pulsed magnetic field gradient generating means, a transmitter for electromagnetic waves in radio-frequency, a radio-frequency receiver, a processor, and a controller. The device to be tracked has attached to its end a small coil of electrically conductive wire. The patient is placed into the magnet means and the device is inserted into the patient. The magnetic resonance imaging system generates electromagnetic waves in radio-frequency and magnetic field gradient pulses that are transmitted into the patient and that induce a resonant response signal from selected nuclear spins within the patient. This response signal induces current in the coil of electrically conductive wire attached to the device. The coil thus detects the nuclear spins in the vicinity of the coil. The radio-frequency receiver receives this detected response signal and processes it and then stores it with the controller. This is repeated in three orthogonal directions. The gradients cause the frequency of the detected signal to be directly proportional to the position of the radio-frequency coil along each applied gradient.
The position of the radio-frequency coil inside the patient may therefore be calculated by processing the data using Fourier transformations so that a positional picture of the coil is achieved. Since however the coil only reacts, literally not a positional picture of the coil but in fact a positional picture of the position of the response signals inside the patient is achieved. Since this positional picture contains no information yet on the region surrounding the immediate vicinity of the coil, this positional picture can be superposed with a magnetic resonance image of the region of interest. In this case the picture of the region may have been taken and stored at the same occasion as the positional picture or at any earlier occasion.
Radio-frequency antennas in the form of a coil couple inductively to the electromagnetic field and they allow obtaining a substantially spatially uniform magnetic field which results in a relatively uniform image intensity over a wide region. The problem is however that coil configurations are bulky (the received signal is determined by the loop diameter) and cannot be implemented for use in narrow vessels, whereby their use for the placement of medical appliances such as catheters may be critical.
Furthermore, the spot image which is provided for by the coil antenna does not allow knowing or even evaluating the orientation of the device; as a result, the magnetic resonance imaging system cannot be used for steering the device into tortuous areas such as blood vessels.
European Patent No 0165742 describes a catheter for use with magnetic resonance imaging systems. This catheter comprises a sheath which has embedded within the wall thereof a pair of conductors preferably formed of a foil composite obtained by plating of conductive materials of selected magnetic susceptibility to yield a composite of desired susceptibility substantially matching that of the sheath. In this way, the magnetic invisibility of the catheter is maintained. The tip of the catheter contains a loop connecting the conductors, the phase of such a loop being preferably transverse to the catheter symmetry axis. As explained in the document, when excited by a weak pulse source, the loop supports a dipole magnetic field which locally distorts the magnetic resonance image providing an image cursor on the magnetic resonance imaging display, and a low magnetic susceptibility functional element such as a light pipe threaded into the catheter sheath allows direction of the catheter through selected blood vessels. The essence of this structure is thus the accurate location and monitoring of the catheter tip.
However, this is achieved within the environment of a bulky configuration which cannot be advanced through narrow vessels and which cannot be steered by reference to the magnetic resonance imaging system.
The document WO 87/04080 shows surgical catheters composed of alternating annular segments of non-magnetic materials which are highly opaque to nuclear magnetic resonance examination and less opaque, respectively. These catheters have thin coatings of silicone rubber on their external surface as well as on internal surface of their main central lumen. A plurality of further lumens are distributed circumferentially within the catheter wall and guidance wires are housed in said lumens, secured at the distal end of the catheter wall and coupled to a joystick at the proximal end of the catheter for individual tightening and relaxing to permit radial guidance of the distal end of the catheter. The central lumen of the catheter and still further secondary lumens arranged in the catheter wall are for the distribution of various drugs or for surgical tools such as optic fiber for laser surgery or suturing devices or still stitching grippers. By these arrangements, location of the catheters is apparent under nuclear magnetic resonance examination, visually at the distal end. These structures are however bulky and they have the same drawbacks as outlined hereinbefore.
European Patent Application published under N 0385367 shows an insertable prostate pick-up probe devised for being a nuclear magnetic resonance receiving device capable of imaging spectra from the human prostate and surrounding tissue; this probe may also be used as the transmit coil for radio-frequency excitation. This probe is intended to be used with an interface network providing the tuning, impedance matching, and decoupling functions, and including a connection to a magnetic resonance imaging scanner.
The probe includes a shaft supporting a patient interface balloon at its distal end, comprising an inner balloon and an outer balloon, the inner balloon being capable of being inflated with air supplied through a lumen within the shaft. A non-stretchable lane formed of an adhesive backed cloth material partly covers the inner balloon and serves as a guide for a flexible receiving coil arranged between the inner balloon and the outer balloon, this coil being electrically connected to the interface via an insulated cable extending through the shaft. Upon inflation, the non-stretchable plane rises and forces the receiving coil and outer balloon against the region of interest so that the receiving coil is in position to receive the best possible radio-frequency signal from the region of interest. Special indentations forming a shell are provided on the outer balloon to act as coil positioners when the balloon is in its uninflated state so that the coil may be repeatedly positioned relative to the shell inside the outer balloon for numerous clinical inflation and deflation cycles. A colored stripe is marked on the shaft, possibly including a scale, for indicating the distance which the shaft has been inserted into the patient and also the radial orientation of the balloon for proper alignment with the region of interest. In operation, the probe is inserted while the patient interface balloon is in the uninflated state; the alignment stripe marked on the shaft is used to radially and longitudinally position the probe within the region of interest. Once the probe is correctly placed, the patient interface balloon is inflated and the receiving coil is forced against the region of interest. The probe is then connected to the interface network via the insulated cable.
This particular arrangement of the radio-frequency coil does not reduce the bulk of the system which cannot be used for narrow or tortuous vessels. Furthermore, the system does not provide for any information as to orientation of the probe for steering purposes.
The document DE-3937052 A1 shows a biopsy tube for use in a magnetic resonance imaging procedure, comprising longitudinally extending coaxial conductor tubes separated by insulator tubes and extending the length of the biopsy tube. In a further embodiment, the conductor tubes are replaced by gutter like portions of coaxial conductor tubes which are separated by an insulator filling. Here again, the result is a bulky configuration which cannot be advanced to narrow vessels. In addition, that kind of assembly is substantially stiff, thereby further preventing the applicability of the instrument in tortuous vessels.
The object of this invention is to improve the possibilities of using magnetic resonance imaging procedures by means of a medical appliance which is simple and efficient, which may continuously provide a full information as to its position and orientation, which occupies a minimal space and which has a great flexibility so as to be capable of reaching narrow and tortuous vascular configurations, which may be actually steered under magnetic resonance imaging, which may be used as an interventional means, and which may also prove efficient in the determination of the vascular configurations.
To this effect, the medical appliance according to the invention complies with the definitions given in the claims.
As opposed to the coil configuration, the open wire length antenna couples capacitively to the electromagnetic field and as the received signal originates from the immediate neighborhood of the open wire length, it becomes possible to obtain an image of the antenna, of its position, as well as of its orientation. Steering of the appliance is thus actually possible. The open wire length antenna may be extremely thin and it may also have a high flexibility, allowing safe driving and passage through vascular configurations, even in tortuous and restricted areas thereof. This opens way to using magnetic resonance imaging procedures in interventional conditions where time and precision are of the essence. By repeatedly measuring, reconstructing, and displaying the image with a very short image repetition time, a magnetic resonance imaging fluoroscopy system can be created. And one could also use the open wire length antenna to make a high resolution image of a vessel wall.
According to a simple inexpensive embodiment, the open wire length antenna may be formed by a coaxial cable.
According to an embodiment aiming very thin configurations, the open wire length antenna may be made of a coaxial cable in which the shield and insulators are respectively made of a conductor coating and insulating coatings. In both these cases, the first and second conducting elements of the coaxial configuration may have the same length or unlike lengths.
According to a further embodiment, also aiming very thin configurations, the open wire length antenna may be made of two conducting strands insulated from one another, twisted or parallel to one another. And these strands may have the same length or unlike lengths.
The open wire length antenna may be included in a catheter and the like. As opposed to coil antennas for which the received signal depends on the loop diameter, the diameter of the open wire length antenna is of secondary relevance and, therefore, the open wire length antenna may be devised to form the whole or part of a guidewire as used in vascular procedures for the positioning of catheters and the like.
These and other objects will become readily apparent from the following detailed description with reference to the accompanying drawings which show, diagrammatically and by way of example only, four embodiments of the invention.
The system shown in
The appliance 9, as exemplified in
The appliance 9 of
However, the insulator 140 14 surrounding the central conductor 130 is replaced by an insulating coating 140, while the shield 15 is replaced by a conductor coating 150 and the insulator 16 by an insulator coating 160. As for the embodiment of
Variants may be envisaged.
For instance, the outer conductor and insulator, 15-16 resp. 150-160, need not be removed from a portion of the distal end 17 resp. 170. Similarly, the outer conductor and insulator may be removed a far greater length from the distal end 17 resp. 170, and it is also possible to have them removed to the proximal end of the guidewire, outside of the patient.
Subject to the precautions or requirements inherent to patient protection, it would be also possible to have the guidewire comprised of a naked conductor 13 or 130, while the insulator 14 or 140 and outer conductor 15, 150 and insulator 16, 160 would be installed towards the proximal end of the guidewire, outside of the patient.
Similarly, the coaxial configuration shown is not compulsory, being possible to have the open wire length antenna as a naked or insulated wire with appropriate polarities arranged for connection thereof to the antenna input of the control station.
As for the previous embodiments, the strands 18 and 19, respectively 22 and 23, may have the same length or unlike lengths.
In both the embodiments of FIG. 4 and
| Patent | Priority | Assignee | Title |
| 10213131, | Oct 21 2014 | Samsung Electronics Co., Ltd. | Method of generating magnetic resonance image and medical imaging apparatus using the method |
| 11015990, | Sep 04 2019 | Grip sensor | |
| 11204290, | Sep 04 2019 | Grip sensor | |
| 11371895, | Sep 04 2019 | Grip sensor | |
| 11846550, | Sep 04 2019 | Bradley, Davis | Grip sensor |
| 7848788, | Apr 15 1999 | LANDMARK COMMUNITY BANK | Magnetic resonance imaging probe |
| 8357187, | Jan 19 2007 | Lockheed Martin Corporation | Hybrid optical-electrical probes for stimulation of nerve or other animal tissue |
| 8632577, | Jan 19 2007 | NERVESENSE LTD | Hybrid optical-electrical probes for stimulation of nerve or other animal tissue |
| 8747447, | Jul 22 2011 | NUROTONE MEDICAL LTD | Cochlear implant and method enabling enhanced music perception |
| 8834545, | Jul 22 2011 | NUROTONE MEDICAL LTD | Optical-stimulation cochlear implant with electrode(s) at the apical end for electrical stimulation of apical spiral ganglion cells of the cochlea |
| 8840654, | Jul 22 2011 | NUROTONE MEDICAL LTD | Cochlear implant using optical stimulation with encoded information designed to limit heating effects |
| 8843217, | Sep 13 2013 | NUROTONE MEDICAL LTD | Combined vestibular and cochlear implant and method |
| 8894697, | Jul 22 2011 | NUROTONE MEDICAL LTD | Optical pulse-width modulation used in an optical-stimulation cochlear implant |
| 8945197, | Jul 22 2011 | NUROTONE MEDICAL LTD | Sight-restoring visual prosthetic and method using infrared nerve-stimulation light |
| 8956396, | Aug 03 2011 | NUROTONE MEDICAL LTD | Eye-tracking visual prosthetic and method |
| 8985119, | Sep 09 2005 | NERVESENSE LTD | Method and apparatus for optical stimulation of nerves and other animal tissue |
| 8998914, | Jul 22 2011 | NUROTONE MEDICAL LTD | Optimized stimulation rate of an optically stimulating cochlear implant |
| 9011508, | Jul 22 2011 | NUROTONE MEDICAL LTD | Broad wavelength profile to homogenize the absorption profile in optical stimulation of nerves |
| 9011509, | Jul 22 2011 | NUROTONE MEDICAL LTD | Individually optimized performance of optically stimulating cochlear implants |
| Patent | Priority | Assignee | Title |
| 4865047, | Jun 30 1988 | City of Hope; CITY OF HOPE, 15000 EAST DUARTE ROAD, DUARTE, CA 91010-0269, A NOT-FOR-PROFIT CORP | Hyperthermia applicator |
| 4960106, | Apr 28 1987 | Olympus Optical Co., Ltd. | Endoscope apparatus |
| 5170789, | Jun 17 1987 | Insertable NMR coil probe | |
| 5211166, | Nov 11 1988 | Instrumentarium Corp | Operative instrument providing enhanced visibility area in MR image |
| 5271400, | Apr 01 1992 | General Electric Company | Tracking system to monitor the position and orientation of a device using magnetic resonance detection of a sample contained within the device |
| 5347221, | Mar 09 1993 | FIVE OAKS RESEARCH INSTITUTE, INC , THE | Truncated nuclear magnetic imaging probe |
| 5348010, | Feb 24 1989 | MEDRAD, INC | Intracavity probe and interface device for MRI imaging and spectroscopy |
| 5358515, | Aug 16 1989 | Deutsches Krebsforschungzentrum Stiftung des Offentlichen Rechts | Microwave hyperthermia applicator |
| 5427103, | Jun 29 1992 | Olympus Optical Co., Ltd. | MRI apparatus for receiving nuclear-magnetic resonance signals of a living body |
| DE3937052, | |||
| EP91577, | |||
| EP165742, | |||
| EP300147, | |||
| EP385367, | |||
| WO8704080, |
| Executed on | Assignor | Assignee | Conveyance | Frame | Reel | Doc |
| Dec 14 1994 | MCKINNON, GRAEME C | SCHNEIDER EUROPE A G | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 016248 | /0701 | |
| Aug 10 2000 | Schneider (Europe) A.G. | (assignment on the face of the patent) | / |
| Date | Maintenance Fee Events |
| Jan 22 2010 | M1553: Payment of Maintenance Fee, 12th Year, Large Entity. |
| Date | Maintenance Schedule |
| Nov 25 2011 | 4 years fee payment window open |
| May 25 2012 | 6 months grace period start (w surcharge) |
| Nov 25 2012 | patent expiry (for year 4) |
| Nov 25 2014 | 2 years to revive unintentionally abandoned end. (for year 4) |
| Nov 25 2015 | 8 years fee payment window open |
| May 25 2016 | 6 months grace period start (w surcharge) |
| Nov 25 2016 | patent expiry (for year 8) |
| Nov 25 2018 | 2 years to revive unintentionally abandoned end. (for year 8) |
| Nov 25 2019 | 12 years fee payment window open |
| May 25 2020 | 6 months grace period start (w surcharge) |
| Nov 25 2020 | patent expiry (for year 12) |
| Nov 25 2022 | 2 years to revive unintentionally abandoned end. (for year 12) |