Localizing a device relative to an instrument

Abstract

This disclosure relates generally to systems and methods for localizing a device relative to an instrument. A sensor of the instrument can be monitored for a change in signaling during a first transition of the device relative to the instrument. The sensor can further be monitored for another change in signaling provided by the sensor of the instrument in response to a second transition of the device relative to the instrument. A transition distance difference can be determined between the first transition and the second transition. A location of the device relative to the instrument can be determined based on a location of the instrument and the transition difference distance.

What is claimed is: 
     
         1 . A method comprising:
 sensing signaling by a sensor that is induced in response to an interrogation field, the sensor fixed to an elongated instrument that is positionable within a patient's body;   detecting at least one transition in the sensed signaling provided by the sensor of during positioning of a distal end of a sheath relative to the instrument to influence detection of the interrogation field by the sensor;   determining a location of the sensor within a three-dimensional coordinate system based on the sensed signaling; and   determining a location of the sheath within the coordinate system based on the detected at least one transition in the sensed signaling and the determined location of the sensor.   
     
     
         2 . The method of  claim 1 , wherein detecting the at least one transition in signaling comprises:
 detecting a first transition in the sensed signaling from a first type of sensor signal provided in response to detecting the interrogation field to a second type of sensor signal provided in response to interference with sensing the induced signaling in response to the interrogation field; and   detecting a second transition in the sensed signaling from the second type of sensor signal to the first type of sensor signal.   
     
     
         3 . The method of  claim 1 , wherein the location of the sheath is determined for each of the first and second transitions. 
     
     
         4 . The method of  claim 1 , wherein the instrument is a guidewire, and
 wherein the sheath comprises an elongated body having a lumen to receive and permit axial movement of the guidewire within the lumen, the elongated body includes at least one marker band circumscribing the lumen proximal the distal end of the sheath to influence the interrogation field detected by the sensor depending on an extent of axial alignment between the marker band and the sensor within the lumen.   
     
     
         5 . The method of  claim 4 , wherein each marker band comprises a magnetic shielding material or a magnetic material. 
     
     
         6 . The method of  claim 4 , further comprising generating an electromagnetic field, corresponding to the interrogation field, to induce the signaling of the sensor. 
     
     
         7 . The method of  claim 6 , further comprising:
 moving the sheath relative to the instrument to position the marker band in axial alignment with the sensor and circumscribe the sensor, the signaling that is induced in response to the electromagnetic field being mitigated in response to the moving to enable detection of the at least one transition in the sensed signaling; and   providing a message to indicate the detected at least one transition in the sensed signaling.   
     
     
         8 . The method of  claim 1 , wherein determining the location of the sheath comprises:
 calculating a distance vector in the three-dimensional coordinate system corresponding to a distance between the determined location of the instrument and a location at which the detected transition in the induced signaling occurs, the location of the sheath being determined based on the calculated distance vector and predetermined dimensions of the sheath.   
     
     
         9 . The method of  claim 1 , further comprising axially moving the sheath relative to the instrument located within a lumen thereof to cause the at least one transition. 
     
     
         10 . The method of  claim 9 , wherein after the location of the sheath is determined with respect to the location of the instrument, the method further comprising: fixing the instrument with respect to the sheath and moving the sheath and the instrument together. 
     
     
         11 . The method of  claim 1 , further comprising:
 generating an output visualization to a display, the output visualization including the determined location of the instrument and the determined location of the sheath superimposed with respect to a graphical representation of an anatomical structure.   
     
     
         12 . The method of  claim 11 , wherein the graphical representation of the anatomical structure is generated as an anatomical model based on acquired image data of one or more endovascular structures. 
     
     
         13 . A method comprising:
 monitoring for a change in signaling provided by a sensor of an instrument during a transition of a device relative to the instrument corresponding to a first transition;   monitoring for another change in signaling provided by the sensor of the instrument in response to a second transition of the device relative to the instrument corresponding to a second transition;   determining a transition distance difference between the first transition and the second transition; and   determining a location of the device based on a determined location of the instrument and the determined transition distance difference.   
     
     
         14 . The method of  claim 13 , wherein the first and second transitions in the signaling are provided by the sensor of during positioning of a distal end of the device relative to the instrument to influence detection of an interrogation field by the sensor, and wherein the location of the device is determined for each of the first and second transitions. 
     
     
         15 . The method of  claim 14 , wherein the instrument is a guidewire, and
 wherein the device comprises an elongated body having a lumen to receive and permit axial movement of the guidewire within the lumen, the elongated body includes at least one marker band circumscribing the lumen proximal a distal end of the elongated body to influence the interrogation field detected by the sensor depending on an extent of axial alignment between the marker band and the sensor within the lumen.   
     
     
         16 . The method of  claim 15 , wherein each marker band comprises a magnetic shielding material or a magnetic material. 
     
     
         17 . The method of  claim 15 , further comprising:
 moving the elongated body relative to the guidewire to position the marker band in axial alignment with the sensor and circumscribe the sensor, the signaling that is induced in response to the electromagnetic field being mitigated in response to the moving to enable detection of the at least one transition in the sensed signaling; and   providing a message to indicate the detected at least one transition in the sensed signaling.   
     
     
         18 . The method of  claim 13 , further comprising generating an electromagnetic field, corresponding to an interrogation field, to induce the signaling of the sensor. 
     
     
         19 . The method of  claim 13 , wherein after the location of the device is determined with respect to the location of the instrument, the method further comprises fixing the instrument with respect to the device and moving the device and the instrument together. 
     
     
         20 . The method of  claim 13 , further comprising:
 generating an output visualization to a display, the output visualization including the determined location of the instrument and the determined location of the device superimposed with respect to a graphical representation of an anatomical structure, wherein the graphical representation of the anatomical structure is generated as an anatomical model based on acquired image data of one or more endovascular structures.