Intra-operative registration for navigated surgical procedures

1. A surgical navigation method comprising the acts of:

establishing a coordinate frame by fixing a first electromagnetic device to a patient;

acquiring two or more two-dimensional fluoroscopic images of the patient each from a different perspective using an imaging apparatus, the imaging apparatus comprising a source of X-ray radiation and an X-ray detector having a second electromagnetic device and a calibration target affixed thereto, and wherein the calibration target comprises a series of radiopaque markers that are fixed in relation to one another;

modeling a geometry of the source of X-ray radiation and the X-ray detector based at least on a geometry of the radiopaque markers in each two-dimensional fluoroscopic image to obtain a perspective from which each image was taken;

providing a pre-operative three-dimensional image, the two or more two-dimensional fluoroscopic images, tracking data representing a position and orientation of the second electromagnetic device with respect to the first electromagnetic device, and the perspective from which each two-dimensional fluoroscopic image was taken to a computerized navigation system;

generating a respective two-dimensional projection via digital radiographic reconstruction (DRR) of the pre-operative three-dimensional image using the perspective from which each two-dimensional fluoroscopic image was taken and an input pose of the imaging apparatus relative to the pre-operative three-dimensional image;

comparing the generated two-dimensional projections to the acquired two or more two-dimensional fluoroscopic images;

updating the input pose based on the comparison to generate updated projections via DRR until the updated projections meet a predetermined matching criteria with the acquired two or more two-dimensional fluoroscopic images, the predetermined criteria being a result of a registration pose; and

generating a substantially real-time three-dimensional visualization of the patient based on the registration pose and the pre-operative three-dimensional image.

2. The method of claim 1 , wherein the comparison between the generated two-dimensional projections and the acquired two or more two-dimensional fluoroscopic images is performed on a pixel-by-pixel basis.

3. The method of claim 1 , wherein at least two of the two or more two-dimensional fluoroscopic images are taken from perspectives that are angled relative to one another.

4. The method of claim 1 , wherein the first electromagnetic device does not comprise an optical sensor or marker.

5. The method of claim 1 , wherein the first electromagnetic device is disposed on or within the patient percutaneously.

6. The method of claim 1 , wherein the first electromagnetic device is attached to a bone of the patient.

7. The method of claim 1 , wherein the three-dimensional representation comprises a CT scan.

8. The method of claim 1 , wherein the two or more two-dimensional fluoroscopic images are acquired using a C-arm imager.

9. The method of claim 1 , wherein the two or more two-dimensional fluoroscopic images comprise two, three, or four two-dimensional fluoroscopic images.

10. A method of surgical navigation comprising the acts of:

attaching a first electromagnetic device to a patient anatomy of interest to establish a coordinate frame;

performing an acquisition of two or more two-dimensional fluoroscopic images using a C-arm imaging system, wherein the C-arm imaging system comprises a second electromagnetic device and a calibration target;

performing a registration operation using a computerized navigation system configured to process the coordinate frame, the two or more two-dimensional fluoroscopic images, a projection model generated using calibration data derived based upon the calibration target and spatial data derived for the C-arm using the second electromagnetic device, digital radiographic reconstruction (DRR) images generated using the projection model and a calculated pose of the C-arm imaging system relative to a three-dimensional representation of the patient anatomy of interest generated prior to surgery, and the three-dimensional representation of the patient anatomy of interest generated prior to surgery, wherein the registration operation generates a three-dimensional visualization of the patient; and

monitoring a representation of a surgical tool depicted with respect to the three-dimensional visualization, wherein the surgical tool is equipped with a third electromagnetic device.

11. The method of claim 10 , comprising:

acquiring additional two-dimensional fluoroscopic images after the three-dimensional visualization is generated; and

updating the registration and the three-dimensional visualization based on the additional two-dimensional fluoroscopic images.

12. The method of claim 10 , wherein the two or more two-dimensional fluoroscopic images are taken from perspectives that are angled relative to one another.

13. The method of claim 10 , wherein the first, second and third electromagnetic devices generate a signal representative of a position and orientation of the patient, the C-arm imaging system, and the medical device, respectively.

14. The method of claim 10 , further comprising viewing the 3D visualization of the device and the patient from a coronal, sagittal, or axial plane perspective of the patient.