Mri radio-frequency heating amelioration for metallic braided catheters

Abstract

An embodiment in accordance with the present invention provides a catheter solution that would maintain MRI-compatible metallic braiding or metallic covering on a surface of the catheter, and that also prevents cables disposed in an interior lumen of the catheter from effectively propagating currents induced from external signal transmissions, which could cause a rise in temperature of the cables themselves and of tissues surrounding the catheter. The present invention uses metals which are non-ferromagnetic and not highly paramagnetic, so they do not cause large susceptibility artifacts in the MRI field. The construction of the braid prevents most of the RF fields from penetrating into the anterior of the catheter. Therefore, there is no need or a reduced need to add heat amelioration components to each electrical cable inside the catheter.

1 . A catheter compatible with magnetic resonance imaging (MRI) comprising:
 a metallic braided or metallic covered catheter; and   a miniature floating resonant radiofrequency trap (MBalun).   
     
     
         2 . The catheter of  claim 1  wherein the MBalun further comprises:
 an electrically conducting tube or braided cable, which forms an inner conductor of the MBalun; 
 an insulating dielectric layer configured to overlay the inner conductor of the MBalun; 
 a large (>1) pitch “leaky” solenoid comprising multiple conductive wire windings configured to overlay the dielectric layer, wherein the solenoid forms the outer conductor of the MBalun; 
 wherein the solenoid is shorted to the inner conductor of the MBalun at one end of the solenoid and is connected to one side of a capacitor at another other end of the solenoid; 
 wherein the capacitor is then connected at its second end to the inner conductor, and wherein the capacitor is used to resonate the MBalun to a desired resonance frequency. 
 
     
     
         3 . The catheter of  claim 2  further comprising the metallic braided catheter and the MBalun having a pattern length of one quarter of a wavelength. 
     
     
         4 . The catheter of  claim 2  further comprising a segment of metallic braided catheter being alternated with a segment of MBalun. 
     
     
         5 . The catheter of  claim 2  further comprising the MBalun being placed around an outside surface of the metallic braided catheter at predetermined intervals. 
     
     
         6 . The catheter of  claim 2  wherein the conductivity of the metallic braided catheter is broken in order to create a short. 
     
     
         7 . The catheter of  claim 5  further comprising a copper shield disposed within an inner lumen of the metallic braided catheter. 
     
     
         8 . The catheter of  claim 6  further comprising the short being directed to the copper shield. 
     
     
         9 . The catheter of  claim 1  wherein the MBalun is configured to remove electromagnetic currents that have been induced on metallic braided or metallic covered catheters from Radio-Frequency (RF) transmitters within the MRI scanner. 
     
     
         10 . The catheter of  claim 1  wherein the MBalun is configured to remove electromagnetic currents that have been induced on wires that are within the metallic braided or metallic covered catheters such single wires, coaxial cables, and twisted pair cables from RF transmitters within the MRI scanner. 
     
     
         11 . The catheter of  claim 2  wherein the MBalun is formed from copper. 
     
     
         12 . A device compatible with magnetic resonance imaging (MRI) comprising:
 a conductive guidewire; and   a miniature floating resonant radiofrequency trap (MBalun) disposed along a length of the guidewire.   
     
     
         13 . The device of  claim 12  further comprising the guidewire and the MBalun having a pattern length of one quarter of a wavelength. 
     
     
         14 . The device of  claim 12  further comprising a segment of guidewire being alternated with a segment of MBalun. 
     
     
         15 . The device of  claim 12  further comprising the MBalun being placed around an outside surface of the guidewire at predetermined intervals. 
     
     
         16 . The device of  claim 12  wherein the MBalun further comprises a metal layer surrounding the guidewire, a dielectric layer, a coil wrapping surrounding the dielectric layer, a capacitor, and a short. 
     
     
         17 . The device of  claim 12  wherein the conductivity of the guidewire is broken in order to create a short. 
     
     
         18 . The device of  claim 17  further comprising a metallic layer being disposed over a portion of the guidewire. 
     
     
         19 . The device of  claim 17  further comprising the short being directed to metallic layer. 
     
     
         20 . The device of  claim 12  wherein the MBalun is formed from copper. 
     
     
         21 . The device of  claim 12  wherein the MBalun is configured to remove electromagnetic currents that have been induced on metallic braided or metallic covered catheters from Radio-Frequency transmitters within the MRI scanner. 
     
     
         22 . The catheter of  claim 1  wherein the MBalun is configured to remove electromagnetic currents that have been induced on wires that are within the metallic braided or metallic covered catheters such single wires, coaxial cables, and twisted pair cables from Radio-Frequency transmitters within the MRI scanner.