Magnetic resonance probes

Abstract

A magnetic resonance probe may include a plurality of center conductors, at least some center conductors including a conductive core and an insulator disposed at least partially about the core along at least a portion of the core, a first dielectric layer disposed at least partially about the plurality of center conductors in a proximal portion of the probe, an outer conductive layer at least partially disposed about the first dielectric layer, and a plurality of electrodes, at least one electrode being coupled to one of the center conductors and disposed at least partly on a probe surface.

We claim: 
     
       1. A magnetic resonance probe, comprising:
 a plurality of center conductors, at least some center conductors;
 including a conductive core and an insulator disposed at least partially about the core along at least a portion of the core; and 
 forming a first pole of a magnetic resonance dipole antenna; 
   a first dielectric layer disposed at least partially about the plurality of center conductors in a proximal portion of the probe;   an outer conductive layer at least partially disposed about the first dielectric layer and forming a second pole of the magnetic resonance dipole antenna; and   a plurality of electrodes, at least one electrode being coupled to one of the center conductors and disposed at least partly on a probe surface.   
     
     
       2. The probe of  claim 1 , further comprising a second dielectric layer at least partially disposed about the outer conductive layer. 
     
     
       3. The probe of  claim 1 , further comprising a lubricious coating at least partially disposed about the outer conductive layer. 
     
     
       4. The probe of  claim 1 , wherein the plurality of center conductors are magnetic resonance-compatible. 
     
     
       5. The probe of  claim 1 , wherein at least one insulator has a thickness equal to or less than about 100 microns. 
     
     
       6. The probe of  claim 1 , wherein at least some center conductors comprise at least one of a magnetic resonance compatible material, a super elastic material, copper, silver-copper, gold, silver, platinum, iridium, MP35N, tantalum, titanium, Nitinol, L605, gold-platinum-iridium, gold-copper-iridium, and gold-platinum. 
     
     
       7. The probe of  claim 1 , further comprising a connection to a high-pass filter through which the probe is coupleable to a magnetic resonance scanner. 
     
     
       8. The probe of  claim 1 , further comprising a connection to a low-pass filter through which the probe is coupleable to at least one of an electrophysiological recording system, a tissue stimulator, and an ablation energy source. 
     
     
       9. The probe of  claim 1 , further comprising:
 a ribbon disposed in a distal portion of the probe; and   a pull wire coupled to the ribbon.   
     
     
       10. The probe of  claim 9 , wherein the pull wire is disposed in a lumen in the probe. 
     
     
       11. The probe of  claim 1 , further comprising a coolant lumen. 
     
     
       12. The probe of  claim 1 , further comprising a plurality of radially expandable arms, wherein at least one electrode is at least partly disposed on one arm. 
     
     
       13. The probe of  claim 12 , further comprising a tubing that is slideably displaceable between at least two positions to transition the expandable arms between a retracted position and an expanded position. 
     
     
       14. The probe of  claim 12 , further comprising a tubing that is slideably displaceable between at least two positions to transition the expandable arms between a retracted position and an expanded position. 
     
     
       15. The probe of  claim 1 , further comprising an ablation electrode disposed at a distal tip of the probe. 
     
     
       16. The probe of  claim 1 , further comprising an interface circuit coupled to the probe, the interface circuit including:
 a signal splitter that directs a signal received from the probe to a magnetic resonance pathway and an electrophysiology pathway;   a high-pass filter disposed in the magnetic resonance pathway;   a low-pass filter disposed in the electrophysiology pathway;   a connector disposed in the magnetic resonance pathway for connecting to a magnetic resonance scanner; and   a connector disposed in the electrophysiology pathway for connecting to at least one of a tissue stimulator, a biopotential recording system, and an ablation energy source.   
     
     
       17. The probe of  claim 1 , wherein the probe has an outer diameter of less than about 15 French. 
     
     
       18. The probe of  claim 1 , wherein the probe has an outer diameter of less than about 4 French. 
     
     
       19. The probe of  claim 1 , further comprising a connector portion disposed at a proximal end of the probe, the connector portion including:
 an outer conductor contact coupled to the outer conductive layer;   extended sections of at least some center conductors extending proximally beyond the outer conductor contact, at least one extended section having a center conductor contact coupled to one center conductor; and   an insulated area interposed between the outer conductor contact and the at least one center conductor contact.   
     
     
       20. The probe of  claim 1 , defining at least one lumen. 
     
     
       21. The probe of  claim 20 , further comprising a pull wire disposed in the lumen, coupled to a distal portion of the probe, and longitudinally displaceable. 
     
     
       22. The probe of  claim 1 , wherein at least one center conductor is coupled to a distal portion of the probe and longitudinally displaceable. 
     
     
       23. The probe of  claim 1 , wherein all of the center conductors collectively form the first pole of the magnetic resonance dipole antenna. 
     
     
       24. A method of performing a magnetic resonance-guided procedure, comprising:
 placing a subject in a magnetic resonance scanner;   identifying a target site in the subject using data about the subject obtained from the scanner;   introducing into the patient a magnetic resonance probe as defined by  claim 1 ;   advancing the probe to the target site; and   performing the procedure using the magnetic resonance probe.   
     
     
       25. The method of  claim 24 , wherein the target site is located in the subject's brain, and the probe is introduced by employing a stereotactic frame. 
     
     
       26. The method of  claim 24 , wherein the target site comprises at least one of the subject's thalamus, globus pallidum internus, and subthalamic nucleus. 
     
     
       27. The method of  claim 24 , further comprising anchoring at least one of the probe's electrodes in the subject. 
     
     
       28. The method of  claim 24 , further comprising electrically connecting at least one of the probe's electrodes to a pacemaker. 
     
     
       29. The method of  claim 24 , wherein the target site is located in the subject's heart. 
     
     
       30. The method of  claim 29 , wherein at least one probe electrode is an RF ablation electrode, and the method further comprises ablating heart tissue. 
     
     
       31. The method of  claim 30 , wherein ablating comprises creating a plurality of linear ablations in the subject's left and/or right atrium. 
     
     
       32. A combined magnetic resonance imaging and electrophysiology probe, comprising:
 a plurality of center conductors, at least some center conductors including a conductive core and an insulator disposed at least partially about the core along at least a portion of the core, the insulator having a thickness equal to or less than about 100 microns;   a first dielectric layer disposed at least partially about the plurality of center conductors in a proximal portion of the probe;   an outer conductive layer at least partially disposed about the first dielectric layer;   a second dielectric layer disposed at least partially about the outer conductive layer; and   a plurality of electrodes, at least one electrode coupled to one of the center conductors and disposed at least partly on the probe surface.   
     
     
       33. A system for magnetic resonance imaging, comprising:
 a magnetic resonance probe, including:
 a plurality of center conductors, at least some center conductors:
 including a conductive core and an insulator disposed at least partially about the core along at least a portion of the core; and 
 forming a first pole of a magnetic resonance dipole antenna; 
 
 a first dielectric layer disposed at least partially about the plurality of center conductors in a proximal portion of the probe; 
 an outer conductive layer disposed at least partially about the first dielectric layer and forming a second pole of the magnetic resonance dipole antenna; and 
 a plurality of electrodes, at least one electrode coupled to one of the center conductors and disposed at least partly on the probe surface; and 
   a interface electrically coupled to the probe, the interface including:
 a signal splitter that directs a signal received from the probe to a magnetic resonance pathway and an electrophysiology pathway; 
 a high-pass filter disposed in the magnetic resonance pathway; 
 a low-pass filter disposed in the electrophysiology pathway; 
 a connector disposed in the magnetic resonance pathway for connecting to a magnetic resonance scanner; and 
 a connector disposed in the electrophysiology pathway for connecting to at least one of a tissue stimulator, a electrophysiological recording system, and an ablation energy source. 
   
     
     
       34. A magnetic resonance interventional probe assembly, comprising:
 a magnetic resonance probe, comprising a steerable distal section attached to a stiff proximal section with a plurality of electrodes held on the distal section, the distal section including a plurality of center conductors which form a first pole of a magnetic resonance dipole antenna and an outer conductive layer which forms a second pole of the antenna, each center conductor including a conductive core and an insulator disposed at least partially about the core, the insulator being configured to electrically couple the plurality of center conductors together when exposed to high frequency radiation and electrically decouple the plurality of center conductors from each other when exposed to low frequency radiation; and   at least one pull wire connected to a distal tip portion of the probe to allow the distal tip to flexibly bend in response to pulling of the pull wire, wherein the probe cooperates with the at least one pull wire to define a loopless magnetic resonance antenna which allows MRI visualization of the probe tip.   
     
     
       35. A magnetic resonance interventional probe assembly according to claim 34, wherein the plurality of insulated center conductors are held in a lumen defined by a first dielectric material. 
     
     
       36. A magnetic resonance interventional probe assembly according to claim 34, further comprising a decoupling circuit comprising a PIN diode, wherein during a receive phase of an MRI scanner, a negative voltage can reverse bias the diode thereby rendering the diode non-conductive, and wherein during a transmit phase of the MRI scanner, a positive voltage cause the PIN diode to be conductive.