U.S. patent application number 11/068342 was filed with the patent office on 2005-06-30 for method and apparatus for virtual endoscopy.
Invention is credited to Hunter, Mark, Kessman, Paul, Verard, Laurent.
Application Number | 20050143651 11/068342 |
Document ID | / |
Family ID | 31187965 |
Filed Date | 2005-06-30 |
United States Patent
Application |
20050143651 |
Kind Code |
A1 |
Verard, Laurent ; et
al. |
June 30, 2005 |
Method and apparatus for virtual endoscopy
Abstract
A surgical instrument navigation system is provided that
visually simulates a virtual volumetric scene of a body cavity of a
patient from a point of view of a surgical instrument residing in
the cavity of the patient. The surgical instrument navigation
system includes: a surgical instrument; an imaging device which is
operable to capture scan data representative of an internal region
of interest within a given patient; a tracking subsystem that
employs electromagnetic sensing to capture in real-time position
data indicative of the position of the surgical instrument; a data
processor which is operable to render a volumetric perspective
image of the internal region of interest from a point of view of
the surgical instrument; and a display which is operable to display
the volumetric perspective image of the patient.
Inventors: |
Verard, Laurent; (Superior,
CO) ; Kessman, Paul; (Broomfield, CO) ;
Hunter, Mark; (Broomfield, CO) |
Correspondence
Address: |
HARNESS, DICKEY & PIERCE, P.L.C.
P.O. BOX 828
BLOOMFIELD HILLS
MI
48303
US
|
Family ID: |
31187965 |
Appl. No.: |
11/068342 |
Filed: |
February 28, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11068342 |
Feb 28, 2005 |
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10223847 |
Aug 19, 2002 |
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6892090 |
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Current U.S.
Class: |
600/424 |
Current CPC
Class: |
A61B 2017/00703
20130101; A61B 2034/2051 20160201; A61B 90/361 20160201; A61B
2034/105 20160201; A61B 2034/2055 20160201; A61B 2034/2072
20160201; A61B 34/10 20160201; A61B 2090/367 20160201; A61B
2090/365 20160201; A61B 34/20 20160201; A61B 2034/107 20160201;
A61B 2034/101 20160201; A61B 90/36 20160201; A61B 2034/256
20160201 |
Class at
Publication: |
600/424 |
International
Class: |
A61B 005/05 |
Claims
What is claimed is:
1. A navigation system to track a surgical instrument relative to a
patient, comprising: a tracking subsystem operable to capture in
real-time position data indicative of the position of the surgical
instrument; a data processor adapted to receive scan data
representative of a region of interest of a given patient and the
position data from the tracking subsystem, the data processor being
operable to render an image of the region of interest from a point
of view which relates to position of the surgical instrument, the
image being derived from the scan data; and a display in data
communication with the data processor, the display being operable
to display the image of the patient.
2. The navigation system of claim 1, further comprising: a timing
signal generator operable to generate and transmit a timing signal
that correlates to at least one anatomical function of the patient;
wherein the tracking subsystem is operable to receive the timing
signal from the timing signal generator, the tracking subsystem
operable to capture position data indicative of the position of the
surgical instrument and to report the position data in response to
the timing signal received from the timing signal generator;
wherein the data processor is adapted to receive scan image data
representative of an internal region of interest within a given
patient and the position data from the tracking subsystem, the data
processor being operable to render a volumetric perspective image
of the internal region of interest from the scan image data and to
superimpose an indicia of the surgical instrument onto the
volumetric perspective image based on the position data received
from the tracking subsystem.
3. The navigation system of claim 2 wherein the timing signal is
generated at a repetitive point within each cycle of either a
cardiac cycle or a respiratory cycle of the patient, thereby
minimizing any jitter of the surgical instrument in the volumetric
perspective image which may be caused by the cardiac cycle or the
respiratory cycle of the patient.
4. The navigation system of claim 2 wherein the data processor is
further operable to the track position of the surgical instrument
as it is moved within the region of interest and to update the
corresponding position of the indicia of the surgical instrument in
the volumetric perspective image of the patient.
5. The navigation system of claim 1 wherein the data processor is
further operable to track in real-time the location and orientation
of the surgical instrument as it is moved within the region of
interest and the display is further operable to display the
location and orientation of the surgical instrument.
6. The navigation system of claim 1, wherein the scan data includes
two dimensional scan data, three dimensional scan data, four
dimensional scan data, or combinations thereof.
7. The navigation system of claim 1, wherein the scan data can be
obtained preoperatively, intra-operatively, from an atlas map, or
combinations thereof.
8. The navigation system of claim 1, wherein the tracking subsystem
is operable to capture real time position data indicative of a
position of the surgical instrument in the patient, an orientation
of the surgical instrument in the patient, or combinations
thereof.
9. The navigation system of claim 1, wherein the tracking subsystem
is an electromagnetic tracking subsystem including a tracking
sensor interconnected with the surgical instrument to assist in
determining a position and orientation of the surgical instrument
relative to the patient.
10. The navigation system of claim 1, wherein the rendered image
displayed on the display is operable to be from the point of view
of the surgical instrument, a point of view at a angle relative to
the surgical instrument, or combinations thereof.
11. The navigation system of claim 5, wherein the data processor is
operable to create a map of the area through which the surgical
instrument is moved by tracking the real time location and
orientation of the surgical instrument over time.
12. The navigation system of claim 11, wherein the map is displayed
on the display.
13. The navigation system of claim 1, wherein the data processor is
operable to compensate for error in the tracking subsystem and/or
inaccuracies caused by anatomical shift caused during acquisition
of the scanned data.
14. The navigation system of claim 1, further comprising: an
imaging device operable to create the scanned data representative
of a region of interest of a given patient.
15. The navigation system of claim 14, wherein said imaging device
includes a magnetic resonance imaging scanner, a computed
tomography scanner, an ultrasound system, a positron emission
tomography, or combinations thereof.
16. The navigation system of claim 1, further comprising: a
disposable surgical instrument.
17. The navigation system of claim 1, further comprising: a
surgical instrument selected from a group consisting of a guide
wire, a pointer probe, a stent, a seed, an implant, an endoscope, a
catheter, or combinations thereof.
18. The navigation system of claim 1, wherein said tracking
subsystem includes wireless communication with the surgical
instrument.
19. The navigation system of claim 1, wherein said tracking
subsystem is an electromagnetic tracking subsystem, an optical
tracking subsystem, a sonic tracking subsystem, an infrared
tracking subsystem, a radiation tracking subsystem, or combinations
thereof.
20. The navigation system of claim 1, further comprising: an
accuracy enhancing subsystem operable to enhance visualization
and/or refined accuracy of the displayed image data; wherein the
enhanced accuracy subsystem is operable to compensate for an error
in the tracking subsystem when tracking the surgical instrument
through a selected vessel.
21. A surgical instrument navigation system to display a virtual
image from the point of view of a surgical instrument within a
patient, comprising: a tracking subsystem operable to capture
position data indicative of the position of the surgical
instrument; a data processor adapted to receive scan image data
representative of an internal region of interest within a given
patient and the position data from the tracking subsystem, the data
processor being operable to render an image of the internal region
of interest from the scan image data and to superimpose an indicia
of the surgical instrument onto the rendered image based on the
position data received from the tracking subsystem; and a display
in data communication with the data processor, the display being
operable to display the rendered image of the patient.
22. The surgical instrument navigation system of claim 21, wherein
the rendered volumetric perspective image of the internal region of
interest of the patient is from a point of view of the surgical
instrument and is displayed on the display.
23. The surgical instrument navigation system of claim 22, wherein
the tracking subsystem is operable to track both a position and an
orientation of the surgical instrument to allow said data processor
to render a volumetric prospective image of the internal region of
interest from a point of view of the surgical instrument.
24. The surgical instrument navigation system of claim 21, wherein
the scan image data is at least one of two dimensional, three
dimensional, four dimensional, or combinations thereof.
25. The surgical instrument navigation system of claim 24, wherein
the data processor is operable to render a volumetric perspective
image of the internal region of interest based upon at least one
scanned image data set of the patient.
26. The surgical instrument navigation system of claim 21, wherein
tracking the subsystem includes a tracking sensor interconnected
with the surgical instrument and a localizing device operable to
determine a position of the tracking sensor; wherein said tracking
subsystem is operable to determine at least a position, an
orientation, or combinations thereof of the tracking sensor.
27. The surgical instrument navigation system of claim 21, wherein
the data processor is operable to render at least one of a
volumetric perspective image, a surface rendered image, or
combinations thereof.
28. The surgical instrument navigation system of claim 21, wherein
the rendered image includes an image from a point of view other
than a point of view of the surgical instrument.
29. The surgical instrument navigation system of claim 21, further
comprising: a secondary image; wherein the data processor is
operable to render a secondary image of the area of interest; and
wherein the display is operable to display the rendered secondary
image.
30. The surgical instrument navigation system of claim 21, wherein
the data processor is operable to render a four dimensional image
of the patient; wherein a change of the patient over time is
illustrated on the rendered image.
31. The surgical instrument navigation system of claim 21, further
comprising: a disposable surgical instrument.
32. The surgical instrument navigation system of claim 21, wherein
said tracking subsystem is an electromagnetic tracking subsystem,
an optical tracking subsystem, an infrared tracking subsystem, a
sonic tracking subsystem, a radiation tracking subsystem, or
combinations thereof.
33. The surgical instrument navigation system of claim 21, further
comprising: at least one surgical instrument selected from a group
consisting of a guide wire, a pointer probe, a stent, a seed, an
implant, an endoscope, a catheter, or combinations thereof.
34. The surgical instrument navigation system of claim 21, further
comprising: an imaging device operable to create the scan image
data.
35. A method of creating image data representative of a point of
view of a surgical instrument relative to a patient for display on
a display, comprising: obtaining image data of a patient; tracking
the surgical instrument; determining a position of the surgical
instrument; determining an orientation of the surgical instrument;
creating image data relating to a point of view of the surgical
instrument within the patient; and displaying the created image
data illustrating the point of view of the surgical instrument
within the patient.
36. The method of claim 35, wherein obtaining image data of the
patient includes obtaining two dimensional image data, three
dimensional image data, four dimensional data, or combinations
thereof.
37. The method of claim 36, wherein displaying the created image
data includes displaying a changeover time of the image data from
the four dimensional image data.
38. The method of claim 35, wherein tracking a surgical instrument,
includes determining a position of a tracking sensor interconnected
with the surgical instrument with a localizing device.
39. The method of claim 35, further comprising: creating secondary
image data relating to a point of view external to an area of
interest of the patient and a surgical instrument.
40. The method of claim 35, wherein creating an image data relating
to a point of view of the surgical instrument within the patient
includes correcting for errors in at least one of determining the
position of the surgical instrument, determining an orientation of
the surgical instrument, a change in the position of the patient
from a present time to the time of obtaining the image data of a
patient, or combinations thereof.
41. The method of claim 40, wherein correcting for errors includes:
using statistical methods to determine if a surgical instrument has
potentially punctured a vessel.
42. The method of claim 41, further comprising: transmitting the
indication error to a user.
43. The method of claim 40, wherein correcting for errors includes
determining a likely position of the surgical instrument within a
vessel based upon image data of the patient and a probable location
of the surgical instrument.
44. The method of claim 35, wherein obtaining image data of a
patient includes obtaining an atlas map image data.
45. The method of claim 35, further comprising: displaying an
indicia of the position of a portion of the surgical instrument
relative to the obtained image data of the patient.
46. The method of claim 35, further comprising: rendering a
volumetric prospective image, rendering a surface rendered image of
the region of interest, or combinations thereof.
47. The method of claim 35, further comprising: displaying a
secondary view relative to the displayed created image data
illustrated in the point of the view of the surgical instrument
within the patient.
48. The method of claim 35, further comprising: interconnecting a
timing signal generator with the patient to track a change in the
patient over time; wherein determining a position of the surgical
instrument and determining orientation of the surgical instrument
includes accounting for the change in the patient determined by the
timing signal generator.
49. The method of claim 35, wherein the timing device measures a
respirator cycle, a cardiac cycle, or combinations thereof to allow
for a reduction of jitter and/or flutter in displaying the created
image data.
50. The method of claim 35 further comprising: obtaining the image
data using at least one of a magnetic resonance imaging system, a
computed tomography imaging system, a positron emission tomography
imaging system, an ultrasound imaging system, or combinations
thereof.
51. The method of claim 35, further comprising: selecting a
disposable surgical instrument.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 10/223,847 filed on Aug. 19, 2002. The
disclosure of the above application is incorporated herein by
reference.
FIELD
[0002] The present teachings relates generally to surgical
instrument navigation systems and, more particularly, to a system
that visually simulates a virtual volumetric scene of a body cavity
from a point of view of a surgical instrument residing in a
patient.
BACKGROUND
[0003] Precise imaging of portions of the anatomy is an
increasingly important technique in the medical and surgical
fields. In order to lessen the trauma to a patient caused by
invasive surgery, techniques have been developed for performing
surgical procedures within the body through small incisions with
minimal invasion. These procedures generally require the surgeon to
operate on portions of the anatomy that are not directly visible,
or can be seen only with difficulty. Furthermore, some parts of the
body contain extremely complex or small structures and it is
necessary to enhance the visibility of these structures to enable
the surgeon to perform more delicate procedures. In addition,
planning such procedures required the evaluation of the location
and orientation of these structures within the body in order to
determine the optimal surgical trajectory.
[0004] Endoscopy is one commonly employed technique for visualizing
internal regions of interest within a patient. Flexible endoscopes
enable surgeons to visually inspect a region prior to or during
surgery. However, flexible endoscopes are relatively expensive,
limited in flexibility due to construction and obscured by blood
and other biological materials.
[0005] Therefore, it is desirable to provide a cost effective
alternative technique for visualizing an internal regions of
interest within a patient.
SUMMARY
[0006] A surgical instrument navigation system is provided that
visually simulates a virtual volumetric scene of a body cavity of a
patient from a point of view of a surgical instrument residing in
the patient. The surgical instrument navigation system generally
includes: a surgical instrument, such as a guide wire or catheter;
a tracking subsystem that captures real-time position data
indicative of the position (location and/or orientation) of the
surgical instrument; a data processor which is operable to render a
volumetric image of the internal region of interest from a point of
view of the surgical instrument; and a display which is operable to
display the volumetric image of the patient. The surgical
instrument navigation system may also include an imaging device
which is operable to capture 2D and/or 3D volumetric scan data
representative of an internal region of interest within a given
patient.
[0007] For a more complete understanding of the present teachings,
reference may be made to the following specification and to the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a diagram of an exemplary surgical instrument
navigation system according to various embodiments;
[0009] FIG. 2 is a flowchart that depicts a technique for
simulating a virtual volumetric scene of a body cavity from a point
of view of a surgical instrument positioned within the patient
according to various embodiments;
[0010] FIG. 3 is an exemplary display from the surgical instrument
navigation system according to various embodiments;
[0011] FIG. 4 is a flowchart that depicts a technique for
synchronizing the display of an indicia or graphical representation
of the surgical instrument with cardiac or respiratory cycle of the
patient according to various embodiments; and
[0012] FIG. 5 is a flowchart that depicts a technique for
generating four-dimensional image data that is synchronized with
the patient according to various embodiments.
DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS
[0013] FIG. 1 is a diagram of an exemplary surgical instrument
navigation system 10. According to various embodiments, the
surgical instrument navigation system 10 is operable to visually
simulate a virtual volumetric scene within the body of a patient,
such as an internal body cavity, from a point of view of a surgical
instrument 12 residing in the cavity of a patient 13. To do so, the
surgical instrument navigation system 10 is primarily comprised of
a surgical instrument 12, a data processor 16 having a display 18,
and a tracking subsystem 20. The surgical instrument navigation
system 10 may further include (or accompanied by) an imaging device
14 that is operable to provide image data to the system.
[0014] The surgical instrument 12 is preferably a relatively
inexpensive, flexible and/or steerable catheter that may be of a
disposable type. The surgical instrument 12 is modified to include
one or more tracking sensors that are detectable by the tracking
subsystem 20. It is readily understood that other types of surgical
instruments (e.g., a guide wire, a pointer probe, a stent, a seed,
an implant, an endoscope, etc.) are also within the scope of the
present teachings. It is also envisioned that at least some of
these surgical instruments may be wireless or have wireless
communications links. It is also envisioned that the surgical
instruments may encompass medical devices which are used for
exploratory purposes, testing purposes or other types of medical
procedures.
[0015] Referring to FIG. 2, the imaging device 14 is used to
capture volumetric scan data 32 representative of an internal
region of interest within the patient 13. The three-dimensional
scan data is preferably obtained prior to surgery on the patient
13. In this case, the captured volumetric scan data may be stored
in a data store associated with the data processor 16 for
subsequent processing. However, one skilled in the art will readily
recognize that the principles of the present teachings may also
extend to scan data acquired during surgery. It is readily
understood that volumetric scan data may be acquired using various
known medical imaging devices 14, including but not limited to a
magnetic resonance imaging (MRI) device, a computed tomography (CT)
imaging device, a positron emission tomography (PET) imaging
device, a 2D or 3D fluoroscopic imaging device, and 2D, 3D or 4D
ultrasound imaging devices. In the case of a two-dimensional
ultrasound imaging device or other two-dimensional image
acquisition device, a series of two-dimensional data sets may be
acquired and then assembled into volumetric data as is well known
in the art using a two-dimensional to three-dimensional
conversion.
[0016] A dynamic reference frame 19 is attached to the patient
proximate to the region of interest within the patient 13. To the
extent that the region of interest is a vessel or a cavity within
the patient, it is readily understood that the dynamic reference
frame 19 may be placed within the patient 13. To determine its
location, the dynamic reference frame 19 is also modified to
include tracking sensors detectable by the tracking subsystem 20.
The tracking subsystem 20 is operable to determine position data
for the dynamic reference frame 19 as further described below.
[0017] The volumetric scan data is then registered as shown at 34.
Registration of the dynamic reference frame 19 generally relates
information in the volumetric scan data to the region of interest
associated with the patient. This process is referred to as
registering image space to patient space. Often, the image space
must also be registered to another image space. Registration is
accomplished through knowledge of the coordinate vectors of at
least three non-collinear points in the image space and the patient
space.
[0018] Registration for image guided surgery can be completed by
different known techniques. First, point-to-point registration is
accomplished by identifying points in an image space and then
touching the same points in patient space. These points are
generally anatomical landmarks that are easily identifiable on the
patient. Second, surface registration involves the user's
generation of a surface in patient space by either selecting
multiple points or scanning, and then accepting the best fit to
that surface in image space by iteratively calculating with the
data processor until a surface match is identified. Third, repeat
fixation devices entail the user repeatedly removing and replacing
a device (i.e., dynamic reference frame, etc.) in known relation to
the patient or image fiducials of the patient. Fourth, automatic
registration by first attaching the dynamic reference frame to the
patient prior to acquiring image data. It is envisioned that other
known registration procedures are also within the scope of the
present teachings, such as that disclosed in U.S. Ser. No.
09/274,972, filed on Mar. 23, 1999, entitled "NAVIGATIONAL GUIDANCE
VIA COMPUTER-ASSISTED FLUOROSCOPIC IMAGING", which is hereby
incorporated by reference.
[0019] During surgery, the surgical instrument 12 is directed by
the surgeon to the region of interest within the patient 13. The
tracking subsystem 20 preferably employs electromagnetic sensing to
capture position data 37 indicative of the location and/or
orientation of the surgical instrument 12 within the patient. The
tracking subsystem 20 may be defined as a localizing device 22 and
one or more electromagnetic sensors 24 may be integrated into the
items of interest, such as the surgical instrument 12. In one
embodiment, the localizing device 22 is comprised of three or more
field generators (transmitters) mounted at known locations on a
plane surface and the electro-magnetic sensor (receivers) 24 is
further defined as a single coil of wire. The positioning of the
field generators (transmitter), and the sensors (receivers) may
also be reversed, such that the generators are associated with the
surgical instrument 12 and the receivers are positioned elsewhere.
Although not limited thereto, the localizing device 22 may be
affixed to an underneath side of the operating table that supports
the patient.
[0020] In operation, the field generators generate magnetic fields
which are detected by the sensor. By measuring the magnetic fields
generated by each field generator at the sensor, the location and
orientation of the sensor may be computed, thereby determining
position data for the surgical instrument 12. Although not limited
thereto, exemplary electromagnetic tracking subsystems are further
described in U.S. Pat. Nos. 5,913,820; 5,592,939; and 6,374,134
which are incorporated herein by reference. In addition, it is
envisioned that other types of position tracking devices are also
within the scope of the present teachings. For instance, non
line-of-sight tracking subsystem 20 may be based on sonic emissions
or radio frequency emissions. In another instance, a rigid surgical
instrument, such as a rigid endoscope may be tracked using a
line-of-sight optical-based tracking subsystem (i.e., LED's,
passive markers, reflective markers, etc).
[0021] Position data such as location and/or orientation data from
the tracking subsystem 20 is in turn relayed to the data processor
16. The data processor 16 is adapted to receive
position/orientation data from the tracking subsystem 20 and
operable to render a volumetric perspective image and/or a surface
rendered image of the region of interest. The volumetric
perspective and/or surface image is rendered 36 from the scan data
32 using rendering techniques well known in the art. The image data
may be further manipulated 38 based on the position/orientation
data for the surgical instrument 12 received from tracking
subsystem 20. Specifically, the volumetric perspective or surface
rendered image is rendered from a point of view which relates to
position of the surgical instrument 12. For instance, at least one
electromagnetic sensor 24 may be positioned at the tip of the
surgical instrument 12, such that the image is rendered from a
leading point on the surgical instrument. In this way, the surgical
instrument navigation system 10 according to various embodiments is
able, for example, to visually simulate a virtual volumetric scene
of an internal cavity from the point of view of the surgical
instrument 12 residing in the cavity without the use of an
endoscope. It is readily understood that tracking two or more
electromagnetic sensors 24 which are embedded in the surgical
instrument 12 enables orientation of the surgical instrument 12 to
be determined by the system 10.
[0022] As the surgical instrument 12 is moved by the surgeon within
the region of interest, its position and orientation are tracked
and reported on a real-time basis by the tracking subsystem 20. The
volumetric perspective image may then be updated by manipulating 38
the rendered image data 36 based on the position of the surgical
instrument 12. The manipulated volumetric perspective image is
displayed 40 on a display device 18 associated with the data
processor 16. The display 18 is preferably located such that it can
be easily viewed by the surgeon during the medical procedure. In
one embodiment, the display 18 may be further defined as a heads-up
display or any other appropriate display. The image may also be
stored by data processor 16 for later playback, should this be
desired.
[0023] It is envisioned that the primary perspective image 38 of
the region of interest may be supplemented by other secondary
images. For instance, known image processing techniques may be
employed to generate various multi-planar images of the region of
interest. Alternatively, images may be generated from different
view points as specified by a user 39, including views from outside
of the vessel or cavity or views that enable the user to see
through the walls of the vessel using different shading or opacity.
In another instance, the location data of the surgical instrument
may be saved and played back in a movie format. It is envisioned
that these various secondary images may be displayed simultaneously
with or in place of the primary perspective image.
[0024] In addition, the surgical instrument 12 may be used to
generate real-time maps corresponding to an internal path traveled
by the surgical instrument or an external boundary of an internal
cavity. Real-time maps are generated by continuously recording the
position of the instrument's localized tip and its full extent. A
real-time map is generated by the outermost extent of the
instrument's position and minimum extrapolated curvature as is
known in the art. The map may be continuously updated as the
instrument is moved within the patient, thereby creating a path or
a volume representing the internal boundary of the cavity. It is
envisioned that the map may be displayed in a wire frame form, as a
shaded surface or other three-dimensional computer display modality
independent from or superimposed on the volumetric perspective
image 38 of the region of interest. It is further envisioned that
the map may include data collected from a sensor embedded into the
surgical instrument, such as pressure data, temperature data or
electro-physiological data. In this case, the map may be color
coded to represent the collected data.
[0025] FIG. 3 illustrates another type of secondary image 28 which
may be displayed in conjunction with the primary perspective image
38. In this instance, the primary perspective image is an interior
view of an air passage within the patient 13. The secondary image
28 is an exterior view of the air passage which includes an indicia
or graphical representation 29 that corresponds to the location of
the surgical instrument 12 within the air passage. In FIG. 3, the
indicia 29 is shown as a crosshairs. It is envisioned that other
indicia may be used to signify the location of the surgical
instrument in the secondary image. As further described below, the
secondary image 28 is constructed by superimposing the indicia 29
of the surgical instrument 12 onto the manipulated image data
38.
[0026] Referring to FIG. 4, the display of an indicia of the
surgical instrument 12 on the secondary image may be synchronized
with an anatomical function, such as the cardiac or respiratory
cycle, of the patient. In certain instances, the cardiac or
respiratory cycle of the patient may cause the surgical instrument
12 to flutter or jitter within the patient. For instance, a
surgical instrument 12 positioned in or near a chamber of the heart
will move in relation to the patient's heart beat. In these
instance, the indicia of the surgical instrument 12 will likewise
flutter or jitter on the displayed image 40. It is envisioned that
other anatomical functions which may effect the position of the
surgical instrument 12 within the patient are also within the scope
of the present teachings.
[0027] To eliminate the flutter of the indicia on the displayed
image 40, position data for the surgical instrument 12 is acquired
at a repetitive point within each cycle of either the cardiac cycle
or the respiratory cycle of the patient. As described above, the
imaging device 14 is used to capture volumetric scan data 42
representative of an internal region of interest within a given
patient. A secondary image may then be rendered 44 from the
volumetric scan data by the data processor 16.
[0028] In order to synchronize the acquisition of position data for
the surgical instrument 12, the surgical instrument navigation
system 10 may further include a timing signal generator 26. The
timing signal generator 26 is operable to generate and transmit a
timing signal 46 that correlates to at least one of (or both) the
cardiac cycle or the respiratory cycle of the patient 13. For a
patient having a consistent rhythmic cycle, the timing signal might
be in the form of a periodic clock signal. Alternatively, the
timing signal may be derived from an electrocardiogram signal from
the patient 13. One skilled in the art will readily recognize other
techniques for deriving a timing signal that correlate to at least
one of the cardiac or respiratory cycle or other anatomical cycle
of the patient.
[0029] As described above, the indicia of the surgical instrument
12 tracks the movement of the surgical instrument 12 as it is moved
by the surgeon within the patient 13. Rather than display the
indicia of the surgical instrument 12 on a real-time basis, the
display of the indicia of the surgical instrument 12 is
periodically updated 48 based on the timing signal from the timing
signal generator 26. In one exemplary embodiment, the timing
generator 26 is electrically connected to the tracking subsystem
20. The tracking subsystem 20 is in turn operable to report
position data for the surgical instrument 12 in response to a
timing signal received from the timing signal generator 26. The
position of the indicia of the surgical instrument 12 is then
updated 50 on the display of the image data. It is readily
understood that other techniques for synchronizing the display of
an indicia of the surgical instrument 12 based on the timing signal
are within the scope of the present teachings, thereby eliminating
any flutter or jitter which may appear on the displayed image 52.
It is also envisioned that a path (or projected path) of the
surgical instrument 12 may also be illustrated on the displayed
image data 52.
[0030] According to various embodiments the surgical instrument
navigation system 10 may be further adapted to display
four-dimensional image data for a region of interest as shown in
FIG. 5. In this case, the imaging device 14 is operable to capture
volumetric scan data 62 for an internal region of interest over a
period of time, such that the region of interest includes motion
that is caused by either the cardiac cycle or the respiratory cycle
of the patient 13. A volumetric perspective view of the region may
be rendered 64 from the volumetric scan data 62 by the data
processor 16 as described above. The four-dimensional image data
may be further supplemented with other patient data, such as
temperature or blood pressure, using coloring coding
techniques.
[0031] In order to synchronize the display of the volumetric
perspective view in real-time with the cardiac or respiratory cycle
of the patient, the data processor 16 is adapted to receive a
timing signal from the timing signal generator 26. As described
above, the timing signal generator 26 is operable to generate and
transmit a timing signal that correlates to either the cardiac
cycle or the respiratory cycle of the patient 13. In this way, the
volumetric perspective image may be synchronized 66 with the
cardiac or respiratory cycle of the patient 13. The synchronized
image 66 is then displayed 68 on the display 18 of the system. The
four-dimensional synchronized image may be either (or both of) the
primary image rendered from the point of view of the surgical
instrument or the secondary image depicting the indicia of the
position of the surgical instrument 12 within the patient 13. It is
readily understood that the synchronization process is also
applicable to two-dimensional image data acquire over time.
[0032] To enhance visualization and refine accuracy of the
displayed image data, the surgical navigation system can use prior
knowledge such as the segmented vessel structure to compensate for
error in the tracking subsystem or for inaccuracies caused by an
anatomical shift occurring since acquisition of scan data. For
instance, it is known that the surgical instrument 12 being
localized is located within a given vessel and, therefore should be
displayed within the vessel. Statistical methods can be used to
determine the most likely location within the vessel with respect
to the reported location and then compensate so the display
accurately represents the instrument 12 within the center of the
vessel. The center of the vessel can be found by segmenting the
vessels from the three-dimensional datasets and using commonly
known imaging techniques to define the centerline of the vessel
tree. Statistical methods may also be used to determine if the
surgical instrument 12 has potentially punctured the vessel. This
can be done by determining the reported location is too far from
the centerline or the trajectory of the path traveled is greater
than a certain angle (worse case 90 degrees) with respect to the
vessel. Reporting this type of trajectory (error) is very important
to the clinicians. The tracking along the center of the vessel may
also be further refined by correcting for motion of the respiratory
or cardiac cycle, as described above.
[0033] The surgical instrument navigation system according to
various embodiments may also incorporate atlas maps. It is
envisioned that three-dimensional or four-dimensional atlas maps
may be registered with patient specific scan data or generic
anatomical models. Atlas maps may contain kinematic information
(e.g., heart models) that can be synchronized with four-dimensional
image data, thereby supplementing the real-time information. In
addition, the kinematic information may be combined with
localization information from several instruments to provide a
complete four-dimensional model of organ motion. The atlas maps may
also be used to localize bones or soft tissue which can assist in
determining placement and location of implants.
[0034] While the teachings has been described in its presently
preferred form, it will be understood that the teachings is capable
of modification without departing from the spirit of the teachings
as set forth in the appended claims.
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