Method and apparatus using shaped field of repositionable magnet to guide implant

• US 6,212,419 B1
• Filed: 11/10/1998
• Issued: 04/03/2001
• Est. Priority Date: 11/12/1997
• Status: Expired due to Fees

• Current Assignee: Stereotaxis, Inc.
• Original Assignee: Stereotaxis, Inc.
• Inventors: Blume, Walter M., Werp, Peter R., Hogg, Bevil J., Ritter, Rogers C.
• Primary Examiner(s): Kamm, William E.
• Application Number:
  US09/189,646
• Time in Patent Office: 875 Days
• Field of Search: 600/9, 600/11, 600/12, 600/300, 600/407, 600/424, 600/434, 604/510, 604/528, 128/899
• US Class Current: 600/407
• CPC Class Codes: A61B 2034/107 Visualisation of planned trajectories or target regions
• CPC Class Codes: A61B 2034/2055 Optical tracking systems
• CPC Class Codes: A61B 2034/733 arranged only on one side of the patient, e.g. under a table
• CPC Class Codes: A61B 34/20 Surgical navigation systems; Devices for tracking or guiding surgical instruments, e.g. for frameless stereotaxis
• CPC Class Codes: A61B 34/70 Manipulators specially adapted for use in surgery
• CPC Class Codes: A61B 34/73 Manipulators for magnetic surgery

Abstract

Methods and apparatuses for displaying and using a shaped field of a repositionable magnet to move, guide, and/or steer a magnetic seed or catheter in living tissue for medicinal purposes. A moveable magnet assembly and a portion of a patient'"'"'s body undergoing magnetically-aided surgery are both provided with fiducial markers. The portion of the patient'"'"'s body is fixed in a location in which the fiducial markers are sensed and located by a set of localizers. The positions of the fiducial markers are determined by a processor, which operates on a stored representation of the magnetic field of a magnet in the magnet assembly to provide a display of the present magnetic field of the magnet. This display may be superimposed over an MRI, X-ray or CAT image during surgery. The repositionable magnet can be an electromagnet. In some embodiments, a computer calculates orientations and currents for an external electromagnet to move the implanted magnetic object in the patient'"'"'s body through a desired path. The display can provide real-time imaging of the implanted magnetic object in comparison to the desired path as the object is moved.

Claims

1. A device for navigating a surgical, diagnostic, or therapeutic object in a patient'"'"'s body, the device comprising:

a) an external magnet mounted on a gantry having an adjustable attitude;

b) a magnetic seed configured for implanting in a patient'"'"'s body; and

c) an imaging system configured to display a medical image of the magnetic seed implanted in a patient'"'"'s body and to superimpose thereon a representation of magnetic field lines of the external magnet, including those representing a near field, the superimposition being dependent upon an orientation and location of the external magnet.

2. The device of claim 1 and further comprising a servo-system mechanically coupled to the gantry.

3. The device of claim 2 wherein the servo-system is configured to provide exclusion zones into which movement of the external magnet and gantry are prevented.

4. The device of claim 1 wherein the imaging system is configured to display two orthogonal projections of the medical image.

5. The device of claim 1 wherein the imaging system is configured to display a rotatable three-dimensional representation of the medical image.

6. The device of claim 1 wherein the imaging system comprises a magnetic field-immune, fluoroscopic imaging system.

7. The device of claim 6 wherein the imaging system comprises a sensor selected from a group consisting of charge coupled device sensors, micro channel plate sensors, and amorphous silicon sensors.

8. A method of magnetic surgery comprising the steps of:

(a) implanting a magnetic seed in a patient'"'"'s body;

(b) imaging a region of the patient'"'"'s body including the implanted seed to thereby produce a medical image;

(c) superimposing on the medical image a representation of a set of magnetic field lines of the external magnet, including those representing a near field, the superimposition being dependent upon an orientation and location of the external magnet;

(d) aligning a portion of the superimposed representation along an intended path of the seed; and

(e) moving the external magnet into a position outside of the patient'"'"'s body to produce the magnetic field represented by the aligned superimposed representation to effect guidance or movement of the seed.

9. The method of claim 8 wherein the external magnet is a permanent magnet, and the aligning and moving steps occur simultaneously.

10. The method of claim 9 wherein the external magnet is an electromagnet, the alignment step occurs first, and the movement step is servo-controlled.

11. A method of computer-aided magnetic surgery comprising the steps of:

(a) implanting a magnetic seed in a patient'"'"'s body;

(b) imaging a region of the patient'"'"'s body including the implanted seed to thereby produce a medical image;

(c) storing information indicative of a path to be taken by the seed in a memory of a computer having a display;

(d) displaying a representation of the path and a current location of the seed on the display;

(e) calculating orientations and currents of an external electromagnet required to provide a magnetic field to the seed to move the seed along the path;

(f) activating a servo-controlled motor to move the external electromagnet to the calculated orientations;

(g) providing the calculated currents to the electromagnet; and

(h) updating the display to provide current locations of the seed relative to the path.

12. The method of claim 11 further comprising providing a non-tactile command to the computer.

13. The method of claim 12 wherein the step of providing a non-tactile command to the computer comprises speaking the command to a voice-recognition unit.

14. A device for navigating a surgical, diagnostic, or therapeutic object in a patient'"'"'s body, the device comprising:

a) an external magnet mounted on a gantry having an adjustable attitude;

b) a magnetic seed configured for implanting in a patient'"'"'s body; and

c) a magnetic locating device for determining and displaying a position and orientation of an implanted magnetic seed.