Antenna for magnetic resonance imaging and method of use

Abstract

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.

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. 
     
     
       2. A medical appliance according to  claim 1 , wherein the open wire length antenna is formed of a coaxial cable including the first and second conductors in a coaxial arrangement. 
     
     
       3. A medical appliance according to  claim 1 , wherein the open wire length antenna is formed of a cable having the first conductor enclosed in the first insulator, the first insulator surrounded by the second conductor and the second conductor encased in a second insulator, and wherein said first conductor and second conductor have the same length. 
     
     
       4. A medical appliance according to  claim 1 , wherein the open wire length antenna is formed of a cable having the first conductor enclosed in the first insulator, the first insulator surrounded by the second conductor, and the second conductor encased in a second insulator, and wherein said first conductor and second conductor have unlike lengths. 
     
     
       5. A medical appliance according to  claim 1 , wherein the open wire length antenna is made of the first conductor, the first insulator includes a first insulating coating applied on said first conductor, the second conductor includes a conducting coating surrounding said first insulating coating, and the antenna further includes a second insulating coating applied on said conducting coating, and wherein said first conductor and conducting coating have the same length. 
     
     
       6. A medical appliance according to  claim 1 , wherein the open wire length antenna is made of the first conductor, the first insulator includes a first insulating coating applied on said first conductor, the second conductor includes a conducting coating surrounding said first insulating coating, and the antenna further includes a second insulating coating applied on said conducting coating, and wherein said first conductor and conducting coating have unlike lengths. 
     
     
       7. A medical appliance according to  claim 1 , wherein the first and second conductors of the open wire length antenna include conducting strands insulated from one another. 
     
     
       8. A medical appliance according to  claim 7 , wherein the first and second conductor means are parallel to one another. 
     
     
       9. A medical appliance according to  claim 7 , wherein the first and second conductor means are twisted. 
     
     
       10. A medical appliance according to  claim 7 , wherein the first and second conductor means have the same length. 
     
     
       11. A medical appliance according to  claim 7 , wherein the first and second conductor means have unlike lengths. 
     
     
       12. A medical appliance according to  claim 1 , wherein the open wire length antenna forms at least a part of a guidewire for vascular procedures. 
     
     
       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.  
 
     
     
       14. A medical appliance according to  claim 13 , wherein the open wire length antenna is formed of a coaxial cable including the first and second conductors in a coaxial arrangement. 
     
     
       15. A medical appliance according to  claim 13 , wherein the open wire length antenna is formed of a cable having the first conductor enclosed in the first insulator, the first insulator surrounded by the second conductor and the second conductor encased in a second insulator, and wherein said first conductor and second conductor have the same length. 
     
     
       16. A medical appliance according to  claim 13 , wherein the open wire length antenna is formed of a cable having the first conductor enclosed in the first insulator, the first insulator surrounded by the second conductor, and the second conductor encased in a second insulator, and wherein said first conductor and second conductor have unlike lengths. 
     
     
       17. A medical appliance according to  claim 13 , wherein the open wire length antenna is made of the first conductor, the first insulator includes a first insulating coating applied on said first conductor, the second conductor includes a conducting coating surrounding said first insulating coating, and the antenna further includes a second insulating coating applied on said conducting coating, and wherein said first conductor and conducting coating have the same length. 
     
     
       18. A medical appliance according to  claim 13 , wherein the open wire length antenna is made of the first conductor, the first insulator includes a first insulating coating applied on said first conductor, the second conductor includes a conducting coating surrounding said first insulating coating, and the antenna further includes a second insulating coating applied on said conducting coating, and wherein said first conductor and conducting coating have unlike lengths. 
     
     
       19. A medical appliance according to  claim 13 , wherein the first and second conductors of the open wire length antenna include conducting strands insulated from one another. 
     
     
       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. 
     
     
       21. A medical appliance according to  claim 20 , wherein the open wire length antenna is formed of a coaxial cable including the first and second conductors in a coaxial arrangement. 
     
     
       22. A medical appliance according to  claim 20 , wherein the open wire length antenna is formed of a cable having the first conductor enclosed in the first insulator, the first insulator surrounded by the second conductor and the second conductor encased in a second insulator, and wherein said first conductor and second conductor have the same length. 
     
     
       23. A medical appliance according to  claim 20 , wherein the open wire length antenna is formed of a cable having the first conductor enclosed in the first insulator, the first insulator surrounded by the second conductor, and the second conductor encased in a second insulator, and wherein said first conductor and second conductor have unlike lengths. 
     
     
       24. A medical appliance according to  claim 20 , wherein the open wire length antenna is made of the first conductor, the first insulator includes a first insulating coating applied on said first conductor, the second conductor includes a conducting coating surrounding said first insulating coating, and the antenna further includes a second insulating coating applied on said conducting coating, and wherein said first conductor and conducting coating have the same length. 
     
     
       25. A medical appliance according to  claim 20 , wherein the open wire length antenna is made of the first conductor, the first insulator includes a first insulating coating applied on said first conductor, the second conductor includes a conducting coating surrounding said first insulating coating, and the antenna further includes a second insulating coating applied on said conducting coating, and wherein said first conductor and conducting coating have unlike lengths. 
     
     
       26. A medical appliance according to  claim 20 , wherein the first and second conductors of the open wire length antenna include conducting strands insulated from one another. 
     
     
       27. A medical appliance according to  claim 20  and further including a receiver electrically connected to the antenna for receiving the magnetic resonance response signals and providing information representative of the position and orientation of the medical appliance. 
     
     
       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.     
     
     
       29. The medical apparatus of  claim 28  wherein the controller is configured to calculate antenna location by processing data to obtain an image of the antenna, antenna position, and antenna orientation. 
     
     
       30. The medical apparatus of  claim 28  wherein the controller is configured to repeatedly measure, reconstruct and store the image to obtain an increased resolution image of the cavity wall. 
     
     
       31. The medical apparatus of  claim 28  wherein the antenna is configured to be capacitively coupled to an EM field generated by the EM radiation. 
     
     
       32. The medical apparatus of  claim 28  wherein the cavity is defined by vasculature in the patient and wherein the antenna is configured for insertion into and passage through the vasculature. 
     
     
       33. The medical apparatus of  claim 32  wherein the antenna forms at least a portion of a guidewire configured for insertion into the vasculature for use in positioning of a catheter. 
     
     
       34. The medical apparatus of  claim 28  wherein the MRI system includes a response signal receiver and processor and a control station, and wherein the controller is implemented as a part of the control station or processor. 
     
     
       35. The medical apparatus of  claim 28  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. 
     
     
       36. The medical apparatus of  claim 35  wherein the first and second elongate conductors are coaxially arranged along at least a portion of a length thereof. 
     
     
       37. The medical apparatus of  claim 35  wherein the first and second elongate conductors are separated by an insulative layer. 
     
     
       38. The medical apparatus of  claim 35  wherein the first and second elongate conductors are formed as a twisted pair. 
     
     
       39. The medical apparatus of  claim 35  wherein the first and second elongate conductors are generally linear and generally parallel to one another. 
     
     
       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.     
     
     
       41. The method of  claim 40  wherein obtaining an image comprises:
   repeatedly calculating antenna location.     
     
     
       42. The method of  claim 41  wherein calculating antenna location comprises:
   processing data to obtain an image of the antenna.     
     
     
       43. The method of  claim 41  wherein calculating antenna location comprises:
   calculating antenna position.     
     
     
       44. The method of  claim 41  wherein calculating antenna location comprises:
   calculating antenna orientation.     
     
     
       45. The method of  claim 40  wherein obtaining an image comprises:
   repeatedly measuring, reconstructing and storing the image to obtain an increased resolution image of the cavity wall.     
     
     
       46. The method of  claim 40  wherein transmitting a response signal comprises:
   capacitively coupling the antenna to an EM field generated by the EM radiation to detect the resonant response.     
     
     
       47. The method of  claim 40  wherein the cavity is defined by vasculature in the patient and wherein inserting an antenna into the cavity comprises:
   inserting the antenna into the vasculature; and        passing the antenna through the vasculature to a site to be imaged.     
     
     
       48. The method of  claim 47  wherein the antenna is configured as a guidewire and further comprising:
   positioning a catheter in the vasculature through use of the guidewire.     
     
     
       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.     
     
     
       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.     
     
     
       51. The medical apparatus of  claim 50  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. 
     
     
       52. The medical apparatus of  claim 50  wherein the antenna is configured to be capacitively coupled to an EM field generated by the EM radiation. 
     
     
       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.     
     
     
       54. The medical apparatus of  claim 53  wherein the body cavity is a blood vessel and further comprising:
   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.     
     
     
       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.     
     
     
       56. The method of  claim 55  wherein obtaining an image comprises:
   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.     
     
     
       57. The method of  claim 56  wherein calculating antenna location comprises:
   repeatedly calculating antenna location.     
     
     
       58. The method of  claim 56  wherein transmitting a response signal comprises:
   capacitively coupling the antenna to an EM field generated by the EM radiation to detect the resonant response.     
     
     
       59. The method of  claim 55  wherein obtaining an MRI image comprises:
   processing data to obtain an image of the antenna.     
     
     
       60. The method of  claim 55  wherein obtaining an MRI image comprises:
   calculating antenna position.     
     
     
       61. The method of  claim 55  wherein obtaining an MRI image comprises:
   calculating antenna orientation.     
     
     
       62. The method of  claim 55  wherein the body cavity is a blood vessel and obtaining an MRI image comprises:
   repeatedly measuring, reconstructing and storing the image to obtain an increased resolution image of the blood vessel wall.     
     
     
       63. The method of  claim 55  wherein the body cavity is defined by vasculature and the antenna is configured as a guidewire and further comprising:
   positioning a catheter in the vasculature through use of the guidewire.     
     
     
       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.     
     
     
       65. The medical apparatus of  claim 64  wherein the first and second elongate conductors are coaxially arranged along at least a portion of a length thereof. 
     
     
       66. The medical apparatus of  claim 64  wherein the first and second elongate conductors are separated by an insulative layer. 
     
     
       67. The medical apparatus of  claim 64  wherein the first and second elongate conductors are formed as a twisted pair. 
     
     
       68. The medical apparatus of  claim 64  wherein the first and second elongate conductors are generally linear and generally parallel to one another.