Electromagnetic dynamic registration for device navigation

Patent metadata

Field	Value
Publication number	US-2016367168-A1
Application number	US-201615187286-A
Country	US
Kind code	A1
Filing date	Jun 20, 2016
Priority date	Jun 19, 2015
Publication date	Dec 22, 2016
Grant date	—

Abstract

A location of a number of fiducial points can be computed. The fiducial points can include impedance locations of an electrode disposed on a catheter in an impedance based coordinate system and magnetic locations of a magnetic position sensor disposed on the catheter in a magnetic based coordinate system. The impedance location of the electrode in the impedance based coordinate system can be transformed into a transformed impedance location of the electrode in the magnetic based coordinate system. A magnetic location of the electrode in the magnetic based coordinate system can be determined. A determination of whether an impedance shift exists between the transformed impedance location of the electrode in the magnetic based system and the magnetic location of the electrode in the magnetic based system can be made. An electromagnetic dynamic registration can be generated between the impedance based coordinate system and the magnetic based coordinate system based on the impedance shift.

First claim

What is claimed:

1 . A method for registration between impedance and magnetic based coordinate systems, the method comprising:
computing a location of a number of fiducial points, wherein the fiducial points include impedance locations of an electrode disposed on a catheter in an impedance based coordinate system and magnetic locations of a magnetic position sensor disposed on the catheter in a magnetic based coordinate system; transforming the impedance location of the electrode in the impedance based coordinate system into a transformed impedance location of the electrode in the magnetic based coordinate system; determining a magnetic location of the electrode in the magnetic based coordinate system; determining whether an impedance shift exists between the transformed impedance location of the electrode in the magnetic based system and the magnetic location of the electrode in the magnetic based system; and generating, with a computer, an electromagnetic dynamic registration between the impedance based coordinate system and the magnetic based coordinate system based on the impedance shift.

2 . The method of claim 1 , further comprising:
computing the location of an additional number of fiducial points; and updating the electromagnetic dynamic registration based on an additional number of fiducial points.

3 . The method of claim 2 , further comprising transitioning between the electromagnetic dynamic registration and the updated electromagnetic dynamic registration via a smoothing function.

4 . The method of claim 1 , wherein determining the magnetic location of the electrode in the magnetic based coordinate system includes transforming the impedance location of the electrode to the magnetic location of the electrode using a known distance between the electrode on the catheter and the magnetic position sensor disposed on the catheter and an orientation of the magnetic position sensor disposed on the catheter.

5 . The method of claim 4 , further comprising transforming the impedance location of the electrode to the magnetic location of the electrode using Rodrigues' rotation model.

6 . The method of claim 1 , wherein determining the magnetic location of the electrode in the magnetic based coordinate system includes transforming the impedance location of the electrode to the magnetic location of the electrode using a known distance between a plurality of electrodes disposed on the catheter.

7 . The method of claim 6 , wherein determining the magnetic location of the electrode in the magnetic based coordinate system is based on two five degree-of-freedom magnetic positioning sensors disposed on the catheter.

8 . The method of claim 1 , wherein determining the magnetic location of the electrode in the magnetic based coordinate system includes determining a Hermite curve between two five degree-of-freedom magnetic position sensors disposed in a distal end and a proximal end of the catheter based on a position and orientation of the two five degree-of-freedom magnetic position sensors and a known distance between electrodes disposed on the catheter.

9 . The method of claim 1 , wherein determining the magnetic location of the electrode in the magnetic based coordinate system includes determining the magnetic location of the electrode based on an affine transformation between the impedance based coordinate system and the magnetic based coordinate system.

10 . The method of claim 1 , wherein determining the magnetic location of the electrode in the magnetic based coordinate system includes computing an affine transformation between the impedance based coordinate system and the magnetic based coordinate system, wherein an Extended Kalman filter is used to infer state variables corresponding to the affine transformation, and wherein the state variables are based on a shape of the catheter.

11 . The method of claim 1 , wherein determining the magnetic location of the electrode in the magnetic based coordinate system includes computing an arc length between two five degree-of-freedom sensors and using a biarc curve to represent the catheter body between the two sensors, wherein the five degree-of-freedom sensors are disposed in a proximal end and a distal end of the catheter.

12 . The method of claim 1 , further comprising registering an impedance location of an electrode on an impedance based medical device with the magnetic based coordinate system using the electromagnetic dynamic registration.

13 . The method of claim 12 , wherein the method includes displaying the location of the impedance based medical device based on the registered location of the electrode with the magnetic based coordinate system.

14 . A non-transitory computer-readable medium storing instructions to generate a registration between impedance and magnetic based coordinate systems, executable by a processing resource to:
compute a location of a number of fiducial points, wherein the number of fiducial points include impedance locations of an electrode disposed on a catheter in an impedance based coordinate system and magnetic locations of a magnetic position sensor disposed on the catheter in a magnetic based coordinate system; compute a global electromagnetic transformation based on the location of the number of fiducial points to transform the impedance location of the electrode in the impedance based coordinate system into a transformed impedance location of the electrode in the magnetic based coordinate system; determine a magnetic location of the electrode in the magnetic based coordinate system; determine whether an impedance shift exists between the transformed impedance location of the electrode in the magnetic based system and the magnetic location of the electrode in the magnetic based system; generate an electromagnetic dynamic registration between the impedance based coordinate system and the magnetic based coordinate system based on the impedance shift; and determine a shift corrected location of an electrode on an impedance based medical device using the electromagnetic dynamic registration.

15 . The non-transitory computer-readable medium of claim 14 , further comprising instructions to determine a secondary electromagnetic dynamic registration in response to a determination that impedance shift exists.

16 . The non-transitory computer-readable medium of claim 15 , further comprising instructions to register an impedance location of the electrode on the impedance based medical device with the magnetic based coordinate system based on the secondary electromagnetic dynamic registration.

17 . The non-transitory computer-readable medium of claim 16 , further comprising instructions to correct the impedance shift based on the secondary electromagnetic dynamic registration.

18 . A system for generating a registration between impedance and magnetic based coordinate systems, comprising:
a first catheter that includes a first electrode and a magnetic position sensor; a second catheter that includes a second electrode; a processor and memory storing non-transitory computer-readable instruction, executable by the processor to: compute a location of a number of fiducial points, wherein the fiducial points include impedance locations of the first electrode in an impedance based coordinate system and magnetic locations of the magnetic position sensor in a magnetic based coordinate system; compute a global electromagnetic transformation based on the location of the number of fiducial points to transform the impedance location of the first electrode in

Assignees

• St Jude Medical Cardiology Div Inc

Inventors

• Malinin Yuriy
• Hill Anthony D
• Thompson Cable P
• Ruetz Linda

Classifications

• A61B90/37

  Surgical systems with images on a monitor during operation · CPC title

• A61B2017/00699

  correcting for movement caused by respiration, e.g. by triggering · CPC title

• A61B5/066 Primary

  Superposing sensor position on an image of the patient, e.g. obtained by ultrasound or x-ray imaging · CPC title

• A61B2034/2074

  Interface software · CPC title

• A61B34/20

  Surgical navigation systems; Devices for tracking or guiding surgical instruments, e.g. for frameless stereotaxis · CPC title