Systems and methods for displaying guidance images with spatial annotations during a guided medical procedure

1. A method of performing tracking and navigation during a medical procedure, the method comprising:

detecting, with a tracking system, signals from one or more fiducial markers associated with a medical instrument, the medical instrument comprising an elongate portion characterized by a longitudinal axis;

processing the signals to determine a position and an orientation of the medical instrument;

employing a coordinate transformation to represent pre-operative image data and the position and orientation of the medical instrument within a common reference frame; and

generating and displaying a navigation user interface comprising:

a virtual representation of the medical instrument;

anatomical and/or functional features associated with the pre-operative image data;

a plurality of virtual spatial annotations positioned at prescribed locations along the longitudinal axis relative to the position of the medical instrument, each virtual spatial annotation having a transverse spatial extent indicating a corresponding different absolute transverse length measure, the transverse spatial extent being determined in a direction orthogonal to the longitudinal axis; and

numeric values of the different absolute transverse length measures that correspond to the spatial annotations;

the virtual spatial annotations thereby enabling a visual representation of the size of anatomical and/or functional features proximal to the longitudinal axis.

2. The method according to claim 1 wherein at least a subset of the virtual spatial annotations are displayed at respective locations along the elongate portion of the medical instrument.

3. The method according to claim 1 wherein at least a subset of the virtual spatial annotations are displayed at respective locations that reside beyond a distal end of the medical instrument.

4. The method according to claim 3 wherein the distance, along the longitudinal axis, between each virtual spatial annotation and the distal end of the medical instrument, is selected such that when the distal end of the medical instrument contacts a bone surface at a suitable entry point associated with the medical procedure, each virtual spatial annotation is displayed proximal to a subregion of interest.

5. The method according to claim 4 wherein the subregion of interest comprises a pedicle of a spine.

6. The method according to claim 5 wherein the medical instrument is an awl.

7. The method according to claim 5 wherein the medical procedure comprises the insertion of a tool, wherein the tool is selectable according to a plurality of tool diameters, and wherein each absolute transverse length measure represents a different tool diameter, thereby permitting the selection of a suitable tool diameter by visual comparison of the virtual spatial annotations with the anatomical and/or functional features.

8. The method according to claim 7 wherein the tool is a fastener.

9. The method according to claim 8 wherein the fastener is a pedicle screw.

10. The method according to claim 1 at least two of the plurality of virtual spatial annotations are spatially distributed along the longitudinal axis.

11. The method according to claim 10 wherein each virtual spatial annotation has a different spatial extent and represents a different respective absolute transverse length measure, and wherein the virtual spatial annotations that are spatially distributed along the longitudinal axis are displayed along the longitudinal axis in an ordered configuration according to an increasing or decreasing size of the respective absolute transverse length measures.

12. The method according to claim 11 wherein the virtual spatially annotation having the largest absolute transverse length measure is displayed nearest to a proximal end of the medical instrument.

13. The method according to claim 1 further comprising generating and displaying a plurality of navigation images, each navigation image including the plurality of virtual spatial annotations, wherein the location of one or more virtual spatial annotations is varied as a function of time relative to the position of the medical instrument during the display of the plurality of navigation images.

14. The method according to claim 1 further comprising, prior to generating and presenting the navigation user interface comprising the virtual spatial annotations:

determining a speed of the medical instrument;

comparing the speed of the medical instrument to a pre-selected threshold; and

determining that the speed of the medical instrument is below the pre-selected threshold.

15. The method according to claim 1 further comprising:

determining a speed of the medical instrument;

comparing the speed of the medical instrument to a pre-selected threshold;

determining that the speed of the medical instrument is below the pre-selected threshold; and

increasing a magnification of the annotations.

16. The method according to claim 1 wherein the navigation user interface includes a legend associating each virtual spatial annotation with its respective absolute transverse length measure.

17. The method according to claim 1 wherein the navigation user interface comprises a visual representation of the longitudinal axis.

18. The method according to claim 17 further comprising displaying a set of spatial graduations along the longitudinal axis.

19. The method according to claim 1 wherein the navigation user interface is a two-dimensional representation of a two-dimensional region, the two-dimensional region including the longitudinal axis.

20. The method according to claim 1 wherein the navigation user interface is a two-dimensional representation of a three-dimensional region, the three-dimensional region including the longitudinal axis.

21. The method according to claim 20 wherein the virtual spatial annotations have a circular shape.

22. The method according to claim 1 wherein each virtual spatial annotation has a different spatial extent and represents a different respective absolute transverse length measure.

23. The method according to claim 1 further comprising, prior to generating and presenting the navigation user interface comprising the virtual spatial annotations:

determining a time duration over which the medical instrument resides within a pre-selected spatial range;

comparing the time duration to a pre-selected time window; and

determining that the time duration is below the pre-selected time window.

24. The method according to claim 1 further comprising:

determining a time duration over which the medical instrument resides within a pre-selected spatial range;

comparing the time duration to a pre-selected time window;

determining that the time duration is below the pre-selected time window; and

increasing a magnification of the annotations.

25. A method of performing tracking and navigation during a medical procedure, the method comprising:

detecting, with a tracking system, signals from one or more fiducial markers associated with a medical instrument, the medical instrument comprising an elongate portion characterized by a longitudinal axis;

processing the signals to determine a position and an orientation of the medical instrument;

employing a coordinate transformation to represent pre-operative image data and the position and orientation of the medical instrument within a common reference frame; and

generating and displaying a navigation user interface comprising:

anatomical and/or functional features associated with the pre-operative image data;

a virtual spatial annotation positioned at a prescribed location along the longitudinal axis relative to the position of the medical instrument, the virtual spatial annotation having a transverse spatial extent indicating a corresponding absolute transverse length measure, the transverse spatial extent being determined in a direction orthogonal to the longitudinal axis; and

a numeric value of the absolute transverse length measure that corresponds to the spatial annotation;

the virtual spatial annotation thereby enabling a visual assessment of the size of anatomical and/or functional features proximal to the longitudinal axis.

26. A method of performing tracking and navigation during a medical procedure, the method comprising:

detecting, with a tracking system, signals from one or more fiducial markers associated with a medical instrument, the medical instrument comprising an elongate portion characterized by a longitudinal axis;

processing the signals to determine a position and an orientation of the medical instrument;

employing a coordinate transformation to represent pre-operative image data and the position and orientation of the medical instrument within a common reference frame; and

generating and displaying a navigation user interface comprising:

anatomical and/or functional features associated with the pre-operative image data;

a plurality of virtual spatial annotations positioned at prescribed locations along the longitudinal axis relative to the position of the medical instrument, each virtual spatial annotation having a transverse spatial extent indicating a corresponding different absolute transverse length measure, the transverse spatial extent being determined in a direction orthogonal to the longitudinal axis; and

numeric values of the different absolute transverse length measures that correspond to the spatial annotations;

the virtual spatial annotations thereby enabling a visual assessment of the size of anatomical and/or functional features proximal to the longitudinal axis.