U.S. patent application number 15/497403 was filed with the patent office on 2017-10-12 for system, method and devices for navigated flexible endoscopy.
The applicant listed for this patent is KONINKLIJKE PHILIPS N.V.. Invention is credited to Neil David Glossop.
Application Number | 20170290491 15/497403 |
Document ID | / |
Family ID | 37772416 |
Filed Date | 2017-10-12 |
United States Patent
Application |
20170290491 |
Kind Code |
A1 |
Glossop; Neil David |
October 12, 2017 |
SYSTEM, METHOD AND DEVICES FOR NAVIGATED FLEXIBLE ENDOSCOPY
Abstract
The invention provides a method and system for method of
determining the shape of a flexible endoscope. The invention may
include registering image-space coordinates of a path of a flexible
endoscope within the anatomy of a patient to patient-space
coordinates of the path of the flexible endoscope within the
anatomy of the patient. In some embodiments, the image space
coordinates of the path of the flexible endoscope may be predicted
coordinates such as, for example, a calculated centerline through a
conduit-like organ, or a calculated "most likely path" of the
flexible endoscope within the anatomy of the patient. In other
embodiments, the path of the flexible endoscope may be an actual
path determined using intra-operative images of the patient's
anatomy with the flexible endoscope inserted therein. The
registered instrument may then be navigated to one or more items of
interest for performance of the endoscopic medical procedure.
Inventors: |
Glossop; Neil David;
(TORONTO, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
KONINKLIJKE PHILIPS N.V. |
EINDHOVEN |
|
NL |
|
|
Family ID: |
37772416 |
Appl. No.: |
15/497403 |
Filed: |
April 26, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11508835 |
Aug 24, 2006 |
9661991 |
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15497403 |
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60710657 |
Aug 24, 2005 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61B 5/06 20130101; A61B
6/12 20130101; A61B 2034/107 20160201; A61B 34/20 20160201; G06T
2207/30048 20130101; G06T 19/003 20130101; A61B 5/065 20130101;
A61B 1/005 20130101; G06T 2210/41 20130101; A61B 90/361 20160201;
A61B 2090/397 20160201; G06T 7/0012 20130101; A61B 34/10 20160201;
A61B 2034/2051 20160201; A61B 1/018 20130101; A61B 1/31 20130101;
A61B 90/36 20160201 |
International
Class: |
A61B 1/005 20060101
A61B001/005; G06T 7/00 20060101 G06T007/00; A61B 34/20 20060101
A61B034/20; A61B 1/31 20060101 A61B001/31; A61B 1/018 20060101
A61B001/018; A61B 5/06 20060101 A61B005/06 |
Claims
1-24. (canceled)
25: A method of determining the shape of a flexible endoscope
inserted into a portion of an anatomy of a patient, comprising:
inserting the flexible endoscope into the portion of the anatomy of
the patient, wherein the endoscope includes at least one working
channel; inserting a tracked elongated member into the working
channel of the flexible endoscope, wherein the tracked elongated
member is equipped with at least one sensor element whose position
and orientation is tracked by a position sensing system; recording
a locus of positions of the at least one sensor elements as the
tracked elongated member is moved within the working channel of the
flexible endoscope; determining the path of the flexible endoscope
inserted into the portion of the anatomy of the patient using the
locus of positions.
26: The method of claim 25, wherein motion of the portion of the
anatomy of the patient is measured and accounted for using one or
more of a cardiac gating device, a respiratory gating device, an
externally placed motion tracking device, and ian internally placed
motion tracking device.
27: The method of claim 25, wherein the step of determining a path
of the flexible endoscope comprises: on a computing device,
receiving one or more preoperative images of the anatomy of the
patient that are preoperative to insertion of the flexible
endoscope including one or more items of interest; calculating
coordinates of a predicted path in a first preoperative frame of
reference corresponding to the one or more preoperative images
based on predicted collisions with interior walls of a conduit
within the anatomy of the patient in the first preoperative frame
of reference; determining coordinates of the one or more items of
interest within the anatomy of the patient in the first
preoperative frame of reference; obtaining coordinates of an actual
path of the flexible endoscope within the anatomy of the patient in
a second intra-operative frame of reference during the insertion of
the flexible endoscope corresponding to a position sensing system
associated with one or more sensor elements within the anatomy of
the patient; registering the coordinates of the preoperative
predicted path of the flexible endoscope with the coordinates of
the actual intra-operative path of the flexible endoscope based on
the predicted collisions with the interior walls of the conduit to
produce at least one transformation matrix relating the first
preoperative frame of reference to the second intra-operative frame
of reference; and creating a display indicating relative locations
of the flexible endoscope and the one or more items of interest
using the at least one transformation matrix.
28: A system for determining the shape of a flexible endoscope
inserted into a portion of an anatomy of a patient, the system
comprising: a flexible endoscope insertable into the portion of the
anatomy of the patient, wherein the endoscope includes at least one
working channel; a tracked elongated member insertable into the
working channel of the flexible endoscope, wherein the tracked
elongated member is equipped with at least one sensor element, a
position and orientation of which sensor element being tracked by a
position sensing system; a control application comprising a
non-transitory program of instructions that are configured to
determine, using the position and orientation, the path of the
flexible endoscope inserted into the portion of the anatomy of the
patient.
29: The system of claim 28, further comprising: a memory device
that records the position of the at least one sensor element as the
tracked elongated member is moved within the working channel of the
flexible endoscope; the control application being configured to
receive one or more preoperative images of the anatomy of the
patient that are preoperative to insertion of a tracked instrument;
the control application being further configured to calculate
coordinates of a predicted path in a first preoperative frame of
reference corresponding to the one or more preoperative images
based on predicted collisions with interior walls of a conduit
within the anatomy of the patient in the first preoperative frame
of reference, and determine coordinates of the one or more items of
interest within the anatomy of the patient in the first
preoperative frame of reference corresponding to the one or more
preoperative images; the at least one sensor element and the
position sensing system being configured to provide coordinates of
an actual path of the tracked elongated member during an insertion
of the tracked instrument within the anatomy of the patient in a
second intra-operative frame of reference corresponding to the
position sensing system; wherein the control application registers
the coordinates of the predicted path of the tracked endoscope with
the coordinates of the actual path of the tracked instrument based
on the predicted collisions with the interior walls of the conduit
to produce at least one transformation matrix relating the first
preoperative frame of reference to the second intra-operative frame
of reference; and a display module that creates a display
indicating the relative locations of the instrument and the one or
more points of interest using the at least one transformation
matrix.
30: The system of claim 28, further comprising one or more of a
cardiac gating device, a respiratory gating device, an externally
placed motion tracking device or an internally placed motion
tracking device, whereby motion of the portion of the anatomy of
the patient is measured and accounted for.
Description
REFERENCE TO PRIOR APPLICATIONS
[0001] This application is a divisional application of U.S.
application Ser. No. 11/508,835, filed Aug. 24, 2006, which claims
the benefit of U.S. Provisional Patent Application No. 60/710,657
filed on Aug. 24, 2005. These applications are hereby incorporated
by reference herein.
FIELD OF THE INVENTION
[0002] The present invention relates to methods and apparatus for
assisting navigated flexible endoscopy.
BACKGROUND
[0003] During exploratory endoscopic procedures such as
colonoscopy, bronchoscopy, endoscopic retrograde
cholangiopancreatography (ECRP) or other endoscopic procedures, it
is desirable to locate any lesions or other areas that are of
interest such as, for example, precancerous changes, bleeding
sites, polyps, nodules, or other areas of interest. Traditional
endoscopic examination consists entirely of an optical examination
of the conduit or area of interest within the anatomy of the
patient. More recently, virtual examination has become more
popular. In virtual endoscopy, computerized tomography (CT),
magnetic resonance (MR), ultrasound, or other diagnostic imaging
methods are first used to locate a suspect lesion either with or
without the assistance of a computer algorithm (e.g., "CAD" or
computer assisted diagnosis). Lesion candidates are then inspected
optically and treated or biopsied as deemed appropriate by the
physician.
[0004] During optical endoscopic examination, it is important to
locate all flagged suspicious regions (e.g., lesions or other areas
of interest) and examine them. In practice, this can be difficult
because there is no way to easily register image-based data
regarding suspect lesions to the patient space (e.g., the real
world location of the suspected lesions). Often the length of the
endoscope from the insertion point into the patient is the only
indication of the location of suspect lesions. Typically this
indication is extremely crude, averaging 10 centimeters (cm) or
more of error. In arborized tissues, such as, the bronchial
pathways of the lungs, physicians frequently become disoriented and
enter a branch other than the desired one.
[0005] The invention is designed to assist in the optical
localization of suspect lesions or other areas of interest that are
initially detected using virtual colonoscopy or other virtual
endoscopy. This invention enables the physician performing the
examination to more efficiently locate suspicious lesion candidates
from imaging scans, such as CT, MR, ultrasound, or other imaging
scans. Once the position of the candidate lesion or other area of
interest is determined from the imaging scan (either manually,
computer assisted, or through the use of a fully automated CAD
software) the (x, y, z) location of the candidate will be recorded
in image (i.e. CT space) or in some other convenient form. The
system then enables these locations to be indicated to the
physician during a conventional optical endoscopic exam, increasing
the likelihood that he will be able to locate and inspect them. The
invention further enables the shape of a flexible endoscope or
other instrument to be determined without the use of additional
imaging.
SUMMARY OF THE INVENTION
[0006] In one embodiment, the invention provides a system and
method for performing and/or assisting in image-guided medical
endoscopic medical procedures. In one embodiment, the system of the
invention may comprise a control unit, a control application, a
tracked medical instrument, a position sensing system, a display
device, and/or other elements.
[0007] In one embodiment, the control unit may include one or more
special purpose or general purpose computers and/or processors
cable of responding to and executing instructions in a defined
manner. The control unit may include, be associated with, and/or be
in communication with a memory device that stores any data
necessary for the performing the features or functions of the
invention such as, for example, image data, position data,
orientation data, coordinate data, transformation matrices, and/or
other data. The control unit may also include, run, and/or support
a control application comprising one or more software modules for
directing and performing one or more data reception, transmission,
data processing, and/or other data manipulation operations
according to the features and functions of the invention. Other
software modules may also be utilized with the system of the
invention.
[0008] In one embodiment, the tracked medical instrument may
include an endoscope equipped with at least one working channel,
optics for viewing the anatomy present at the distal tip of the
endoscope, one or more trackable sensor elements, and/or other
elements. The position and/or orientation of the one or more sensor
elements may be determined/monitored by the position sensing
system. The position sensing system may be in communication with
the control unit and may provide sampled position coordinates and
orientation information of the one or more sensor elements to the
control unit. An example of the position sensing system is an
electromagnetic position sensing system used with electromagnetic
sensor elements.
[0009] In some embodiments, the tracked medical instrument may
include an untracked endoscope or other instrument used in
conjunction with a tracked catheter, tracked guidewire, tracked
treatment device, and/or other tracked instrument. In some
embodiments, the tracked medical instrument may be a tracked
endoscope. In some embodiments, the system of the invention may not
include an endoscope, but may include one or more tracked devices
that do not include the optics typically associated with an
endoscope.
[0010] The system of the invention may also include a display
device that displays images used in the system and methods of the
invention such as, pre-operative images of the anatomy of a patient
(including one or more items of interest), intra-operative images
of the anatomy of the patient (including an inserted medical
instrument and the one or more items of interest), real-time or
near-real-time images displaying motion of the tracked instrument
relative to the one or more items of interest within the anatomy of
the patient, and/or other images or data.
[0011] In one embodiment, the invention provides a method for
performing and/or assisting with an image-guided medical procedure,
wherein a path of the tracked medical instrument in image space is
registered to the path of the medical instrument in patient space.
The path of the medical instrument in image space may be obtained
from one or more pre-operative images and/or one or more
intra-operative images of the anatomy of the patient. The path of
the medical instrument in patient space may be obtained using a
position sensing system and one or more sensor elements located on
the medical instrument itself or on a separate tracked instrument.
The patient space data is then registered to the image space data
to produce a registration matrix relating the patient space to the
image space. This registration matrix may be used to display the
location and movement of the medical instrument on the one or more
pre or intra-operative images so as to navigate to the one or more
items of interest within the anatomy of the patient.
[0012] In one embodiment, the method of the invention includes
obtaining one or more pre-operative images of a portion of the
anatomy of a patient, wherein the portion of the anatomy of the
patient includes the one or more items of interest. For example, if
the medical procedure was a colonoscopy for the investigation of
one or more colonic lesions, the one or more pre-operative images
may be taken of the colon and/or digestive tract of the patient.
The pre-operative images may comprise image data obtained using,
x-rays, computerized tomography (CT), magnetic resonance (MR),
positron emission tomography (PET), ultrasound, and/or other
imaging modalities.
[0013] In one embodiment, the pre-operative image data is then
examined to determine the locations of candidate lesions or other
items or points of interest in the patient's anatomy. In one
embodiment, these locations are expressed in the coordinate system
of the pre-operative imaging modality (i.e. the "pre-operative
image space"). As such, the location of all lesions or items of
interest is expressed in terms of a frame of reference intrinsic to
the pre-operative image-gathering device.
[0014] In some embodiments, this examination may be performed by a
physician, technician, or other individual. In other embodiments,
the examination may be partially assisted by diagnostic software
modules (e.g., one or more modules comprising the control
application). In still other embodiments, this examination may be
completely automated using one or more software modules or
applications.
[0015] In one embodiment, such as, when the anatomy involved in the
medical procedure includes a channel-like organ or region (e.g.,
the colon, bronchial system, or other channel-like region) the
centerline of a path through the anatomy/organ may calculated. For
example, if the anatomy on which the procedure is performed is the
patient's colon, the centerline may be calculated and represented
by a locus of points that form a path defining the approximate
centerline of the colon. Because these coordinates are derived from
the one or more pre-operative images, these coordinates are
expressed relative to the pre-operative image space.
[0016] In one embodiment, a skeleton or "graph" of a pathway to the
organ may also be determined. This may be particularly useful if
the conduit/organ in which the items of interest are located is
arborized (e.g., bronchial passages). The graph represents a map
from start to target (e.g., a lesion or other item of interest)
along the centerline of any branches in the organ (e.g., the
bronchi of a lung) indicating the direct path to the target,
including all turns.
[0017] In another embodiment, rather than a calculated centerline,
the "most likely path" of the passage of a flexible endoscope or
other flexible instrument is calculated using the one or more
pre-operative images. The coordinates of a plurality of points
defining this "most likely path" are determined in the
pre-operative image space. In some instances, the most likely path
of an endoscope may include points that intersect the walls of any
conduit-like anatomy in the anatomical region (e.g., the endoscope
may collide with the walls of the colon), rather than points that
follow a centerline path through the anatomy. Using mathematical
predictive techniques, this "most likely path" of an
endoscope/instrument can be calculated. In some embodiments,
determination of the most likely path uses a predictive collision
detection system that predicts the endoscope locations touching the
walls of channel-like anatomy such as, for example, at locations
with sharp curvature (e.g., the junction between the
ascending-transverse and transverse-descending colon). In some
embodiments, this predicted path may also be measured, as discussed
below.
[0018] In one embodiment, the medical procedure may begin, usually
by insertion of the medical instrument. For example, if the medical
procedure included a colonoscopy, the medical procedure may include
insertion of a colonoscope or other endoscope into the colon of the
patient. The medical instrument may be inserted into the anatomy of
interest in a manner known in the art. In some embodiments, this
can be done by inserting the instrument into natural or
artificially created orifice of the patient.
[0019] In some embodiments, wherein the endoscope and/or other
medical instrument is visible to an imaging modality,
intra-operative images of the anatomy of the patient may be taken
with the endoscope inserted. The intra-operative imaging may be
used to precisely determine the location of the path of the
endoscope and/or other instrument following insertion. For example,
in one embodiment, the path of the endoscope can be obtained using
two or more fluoroscopic shots taken at different angles, a CT
scan, ultrasound images, or other images taken following insertion
of the endoscope. This intra-operative imaging may also be used to
determine the location of the lesions or other areas of interest
relative to the inserted endoscope.
[0020] In general, the intra-operative images may be obtained in a
new coordinate system/frame of reference (i.e., "intra-operative
image space"). In some embodiments, as discussed herein, the path
of the endoscope determined using the intra-operative images may be
matched or registered with the coordinate system of the
pre-operative images on which the candidate lesions, or other items
of interest have been annotated, and on which the predicted path of
the endoscope (e.g., centerline path or most likely path) has been
calculated.
[0021] The centerline path and/or the most likely path of the
endoscope calculated in the pre-operative image space may differ
from the actual path taken by the inserted endoscope. As such, the
intra-operative images provide the "true path" of the endoscope.
The true path of endoscope becomes available once the
intra-operative imaging is performed and analyzed. Registering the
intra-operative image data with the pre-operative image data
provides a more accurate set of image space data regarding the path
of the endoscope and provides a richer set of data regarding other
features of the anatomy of the patient.
[0022] In some embodiments, it may be desirable to determine the
contortions that the endoscope or other instrument has undergone
without the use of images. For example, a colonoscope frequently
undergoes loops and other deformations that affect a medical
procedure being performed with the colonocsope. Normally, it is
difficult to determine these deformations without imaging. If a
tracked elongated member is dragged through a channel of the
endoscope or other instrument, the locus of points gathered as the
position of sensor elements in the tracked member are sampled
prescribe a shape that is the same as the shape of the endoscope or
other instrument. This information may be used to assist in the
medical procedure. In some embodiments, only a single sensor
element attached to a slidable elongated member (e.g., a guidewire)
is needed to determine this shape. In some embodiments, multiple
sensor elements may be fixed to or moved along the endoscope or
other instrument to determine its path. In some embodiments, motion
may be compensated for by using a dynamic reference device such as,
for example, a skin motion tracker, an internally-placed catheter,
or other dynamic referencing device. Motion may also be compensated
for using a gating device such as, for example, an ECG
(electroencephalogram), a respiratory gating device, or other
gating device.
[0023] To conduct or assist image-guided surgery, it is desirable
to register or match the coordinate system of the position sensing
system to the coordinate system belonging to the pre-operative
image space, intra-operative image space, or a co-registered
combination of the pre and intra-operative images. One way of
facilitating this is by acquiring a plurality of points in position
sensor space or "patient space" (i.e., the coordinate system/frame
of reference intrinsic to the position sensing system) and
mathematically matching them to the same points in image space.
[0024] This may be done by first obtaining patient space data
regarding the endoscope or other instrument within the anatomy of
the patient. This patient space data may be obtained using the
position sensing system and the one or more sensor elements located
on the endoscope or other medical instrument.
[0025] The position sensing system is associated with its own
coordinate system (i.e., a frame of reference intrinsic to the
position sensing system). The position sensing system is capable of
determining the position and orientation of one or more sensor
elements attached to an instrument (e.g., the endoscope or another
instrument) and relaying that information to the control unit.
[0026] Acquisition of data in patient space can be performed by
dragging a tracked endoscope or other instrument back through the
anatomy of the patient (e.g., dragging it back through the colon)
or a tracked instrument back through the working channel of the
endoscope (or the working channel of a catheter or other instrument
inserted into the patient's anatomy) while the position sensing
system gathers/samples data points regarding the position and/or
orientation of the sensor elements on the tracked instrument in the
frame of reference/coordinate system of the position sensing
system. This technique may be labeled a "dragback" technique. More
information regarding the use of this technique and other
information relevant to registration, dynamic referencing, and
other image guided surgery techniques can be found in U.S. patent
application Ser. No. 11/059,336 (U.S. Patent Publication No.
20050182319), which is hereby incorporated by reference herein in
its entirety.
[0027] In some embodiments, instead of, or in addition to, using
the dragback method described above for obtaining data points in
patient space, individual identifiable locations in the anatomy of
the patient are sampled by touching or indicating them with the
tracked instrument or endoscope. In some embodiments, a tracked
instrument may be temporarily secured in the endoscope and sensor
element positions sampled (i.e., not dragged through the
endoscope). In some embodiments, a tracked ultrasound device may be
used to indicate points.
[0028] In one embodiment, registration of the patient space data to
the image space data may involve only image space data acquired
pre-operatively. For example, in one embodiment, the patient space
path of the endoscope acquired using a tracked instrument and the
position sensing system may be registered to pre-operative image
space data relating to the "assumed" path of the endoscope (i.e.
based on the centerline path or the "most likely path" calculated
using the pre-operative images).
[0029] In some embodiments, however, the patient space data may be
registered to the intra-operative image space data. For example,
the image space path of the endoscope registered to the patient
space data may be based on the directly measured path of the
inserted endoscope observed in the intra-operative images (e.g.,
the "true path"). Directly measured or true paths may require a
method expressing the coordinates of this path in the same frame of
reference as the candidate lesions (e.g., the above-discussed
co-registration of the pre-operative images to the intra-operative
images). In these embodiments, a separate registration must be
performed to match the pre-operative images to the intra-operative
images before the combined image data is registered to the patient
space data. In one embodiment, this is done by using 2D-3D or 3D-3D
co-registration techniques.
[0030] Once at least two representations of the endoscope's path
have been determined (i.e. in image space [pre-operative and/or
intra-operative] and in patient space), they may be "matched" or
"registered". The two paths may be matched using an iterative
closest points (ICP), piecewise ICP, or similar algorithm. This
enables a registration matrix (or sequence of registration
matrices) to be generated. In some embodiments, the registration
takes the form of a rigid transformation matrix. In some
embodiments, the registration uses an affine transformation. In
some embodiments, several matrices are used at different places. In
some embodiments, weighted combinations of matrices are used. In
some embodiments, complex matrices embodying deformable
transformations are used.
[0031] In some embodiments, registration may be accomplished using
techniques other than or in addition to the dragback technique
described above. For example, in one embodiment, a "landmark-based"
method may be used that includes the identification of "fiducials"
present in both pre-operative images and identified during the
examination by, for example, touching them with a tracked
instrument or imaging them with a tracked calibrated ultrasound
transducer to determine their location in patient space. If at
least 3 such points are co-located, a registration can be performed
using techniques such as the ICP above or simpler methods such as
singular valued decomposition. In some embodiments, the fiducials
can be naturally occurring landmarks, such as polyps, and in other
embodiments, they can be artificial landmarks such as small balls,
surgical staples, specially placed needles, or other elements that
may be visible in both the pre-operative images and intra-operative
images. Other registration methods may also be used.
[0032] In some embodiments, the endoscope or other elongated
instrument may be equipped with additional sensor elements that can
act as dynamic referencing or tracking sensors, either with
multiple sensor elements placed along the scope or one or two
sensor elements located at the most distal end of the scope. These
track gross patient movement or the motion of the field generator
of the position sensor system as long as the endoscope or other
elongated instrument remains stationary.
[0033] In some embodiments, dynamic references (i.e., sensor
elements) can be placed into additional catheters, guidewires, or
instrument placed elsewhere in/on the patient that are not affected
by the exam. The purpose of these sensor elements is to account for
patient movement, including that occurring from respiration, or
other patient movement.
[0034] Once registration has been performed, the invention may
include a navigation step in which the endoscope or other
instrument equipped with sensor elements is tracked by the position
sensing system. As the endoscope is moved through the anatomy to
inspect its interior, the position of the endoscope or tracked
instrument may be sampled in the reference frame of the position
sensing system. The locations and orientations determined by the
position sensing system are sent to the control unit, which creates
a real-time or near real-time display of the motion of the tracked
instrument relative to the lesions or other points of interest as
identified in the image space. The display is enabled by the
transformation matrix produced by the registration. This display is
used, for example, for image-guided navigation of the endoscope in
an attempt to locate suspect lesions or other items of interest
using the optics of the endoscope.
[0035] In some embodiments, the only information required may be
the shape of the endoscope or other instrument. This may be
acquired without having to explicitly perform a registration
step.
[0036] In some embodiments, whenever one of the flagged locations
(i.e., lesions or other items of interest) is in the proximity of
the tracked portion of the endoscope or other instrument, the
physician may be notified or he or she will be able to determine
from the images that he or she is in proximity of the suspect
lesion and can look for it.
[0037] In some embodiments, the lesions or other items of interest
can then be treated, destroyed, biopsied, or otherwise treated, if
detected. This treatment may be enabled by treatment-oriented
instruments, that may be tracked themselves, and which may be
inserted through the working channel of the endoscope that has been
navigated to a lesion or other item of interest.
[0038] In some embodiments, the sensor elements on a trackable
guidewire act simply as a distance measurement device to determine
the location of the endoscope relative to a known location. In this
embodiment, the relative location of all suspect lesions are
calculated relative to each other and landmarks within the anatomy.
As each is examined, the location is stored and the distance to the
next location of interest is calculated. In this way, the system is
self-correcting at each identified location along the path of the
endoscope as it is removed. This method may not require
registration to be performed prior to use.
[0039] For example, during a "virtual colonoscopy," suspect lesions
may be flagged (on the preoperative images) by the physician or
computer program, and their locations calculated in the frame of
reference of the images.
[0040] During the intervention, the colonoscope is inserted into
the colon and a reference point is identified (for example, the
ileocecal sphincter or appendiceal orifice). The path length of
each of the suspect lesions is identified relative to this location
along the centerline of the colon. For a first lesion, the path is
the length of the distance along the centerline of the colon
between the reference point (e.g., the appeniceal orifice) and the
first suspect lesion. Likewise, the path length of a second lesion
is the length of the distance along the centerline between the
reference point (e.g., the appeniceal orifice) and the second
suspect lesion. Thus by dragging the endoscope back and calculating
the distance traversed by the sensor attached to the endoscope, the
location of the next suspect lesion can be determined.
[0041] Once the first lesion is encountered, the locations of the
next lesions may be calculated relative to it. For example, the
second suspect lesion can be estimated to be located a distance
from the first lesion (or equivalently a distance from the
appeniceal orifice). In general it may be more accurate to estimate
measure the inter-lesion distances, rather than the distance
between the start point and each lesion.
[0042] In one embodiment, the physician indicates each lesion as it
is encountered and in one embodiment, the lesions and landmarks are
weighted according to their distance from the reference point.
[0043] In one embodiment, these measured distances are augmented
using shape information regarding the endoscope or other
instrument, as may be determined using a path determination method
such as those described herein. This shape information may be
helpful in more accurately determining the location of an area of
interest.
[0044] These and other objects, features, and advantages of the
invention will be apparent through the detailed description of the
preferred embodiments and the drawings attached hereto. It is also
to be understood that both the foregoing general description and
the following detailed description are exemplary and not
restrictive of the scope of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0045] FIG. 1 illustrates an example of a process for assisting an
image-guided endoscopic procedure, according to an embodiment of
the invention.
[0046] FIG. 2 illustrates an example of a pre-operative image of a
portion of an anatomy of a patient, according to an embodiment of
the invention.
[0047] FIG. 3 illustrates an example of the "most likely path" of
an endoscope through a conduit, according to an embodiment of the
invention.
[0048] FIG. 4A illustrates an example of a system for image-guided
endoscopy used in the anatomy of a patient, according to an
embodiment of the invention.
[0049] FIG. 4B illustrates an example of a tracked elongated
instrument within an endoscope used in the anatomy of a patient,
according to an embodiment of the invention.
[0050] FIGS. 5A and 5B illustrate an example of a steerable
catheter, according to an embodiment of the invention.
[0051] FIG. 6 illustrates an example a process for
registration-free navigation during an endoscopic procedure,
according to an embodiment of the invention.
[0052] FIG. 7 illustrates an example of an image of a portion of
the anatomy of a patient, according to an embodiment of the
invention.
DETAILED DESCRIPTION
[0053] In one embodiment, the invention provides method for
assisting an image-guided endoscopic procedure. FIG. 1 illustrates
a process 100, an example of a method for assisting an image-guided
endoscopic medical procedure. In an operation 101, a conventional
virtual endoscopic data set may be acquired prior to commencement
of the medical procedure using existing standard protocols such as,
for example, those described in A. K. Hara et al., Reducing Data
Size and Radiation Dose for CT Colonography, 168 American Journal
of Roentgenology 1181-1184 (1997), which is hereby incorporated by
reference herein in its entirety.
[0054] The virtual endoscopic data set may comprise image data
obtained using x-rays, computerized tomography (CT), magnetic
resonance (MR), positron emission tomography (PET), ultrasound,
and/or other imaging modalities. In some embodiments, the
pre-operative imaging may be performed with the patient in same
position as the endoscopic procedure. In some embodiments the
endoscopic procedure occurs in the same room as the pre-operative
imaging.
[0055] In an operation 103, the pre-operative image data may then
by examined by a physician, technician, or other individual. In
some embodiments, this examination may include the assistance of
computer assisted diagnostic software such as, for example, that
described in Ronald M. Summers et al., Colonic Polyps:
Complementary Role of Computer-aided Detection in CT Colonography,
225 Radiology 391-399 (2002), which is hereby incorporated by
reference herein in its entirety. In some embodiments, this
examination may be completely automated using one or more software
modules or applications.
[0056] During the examination of operation 103, the locations of
candidate lesions or other items or points of interest in the
patient's anatomy are determined. In one embodiment, these
locations are expressed in the coordinate system of the
pre-operative images (i.e. "pre-operative image space"). As such,
the location of all lesions or items of interest is expressed in
terms of a frame of reference intrinsic to the pre-operative
image-gathering device.
[0057] FIG. 2 illustrates an example image 200 of a part of an
anatomy of a patient, including colon 201 and small intestine 203.
Identified candidate lesions are indicated as 205a, 205b, 205c,
205d, 205e, and 205f. A region of interest is indicated as 207. All
identified lesions, regions, or other points or items of interest
are expressed in terms of a coordinate system 209 that is a frame
of reference intrinsic to the image gathering device used to
produce image 200.
[0058] In an operation 105, a predicted path of a flexible
endoscope or other instrument through the anatomy of the patient
wherein the one or more points of interest reside is determined.
For example, in one embodiment, the centerline of a path through
the patient's anatomy is obtained. For instance, if the anatomy on
which the procedure is performed is a channel-like organ or region
(e.g. the colon, bronchial system, or other channel-like region),
the predicted path of a flexible endoscope may comprise a locus of
points that form a path defining the approximate centerline of the
organ. The coordinates of these points are determined in the
pre-operative image space. Image 200 of FIG. 2 illustrates
calculated centerline 211 through colon 201.
[0059] In another embodiment, rather than a calculated centerline,
the predicted path of the endoscope comprises a "most likely path"
of the passage of a flexible endoscope that is charted on the
pre-operative images. The coordinates of a plurality of points
defining this "most likely path" are determined in the
pre-operative image space. In some instances, the most likely path
of an endoscope may include points that intersect or collide with
the walls of the patient's anatomy, rather than points that follow
a centerline path through the anatomy. Using mathematical
predictive techniques, this "most likely path" of an endoscope can
be assumed. In some embodiments, determination of the most likely
path uses a predictive collision detection system that predicts an
endoscope location that touches the walls of channel-like anatomy
at locations with sharp curvature such as, for example, the
junction between the ascending-transverse and transverse-descending
colon.
[0060] FIG. 3 illustrates a portion of colon 201, wherein a
predicted "most likely path" of an endoscope is indicated as path
301. An endoscope 303 is shown along part of most likely path 301.
Endoscope 303, as illustrated, collides with the wall of colon 201
at location 305. Rather than follow the path of centerline 211,
endoscope 303 is most likely to follow path 301.
[0061] In some embodiments, during operations 103 and/or 105, one
or more anatomical points of interest may also be noted and their
coordinates in pre-operative image space may be determined. For
example, as illustrated in image 200 of FIG. 2, if the anatomy of
the patient upon which the medical procedure is being performed
includes colon 201, the location of ileocecal sphincter 213,
appendiceal orifice 215, or other anatomical points of interest may
be noted and/or their positions in the image space may be
determined.
[0062] In one embodiment of the invention, the patient undergoes an
optical endoscopic examination or other medical procedure using
traditional endoscopic techniques and/or instruments augmented with
one or more sensor elements, as described herein.
[0063] FIG. 4A illustrates a portion of the anatomy of a patient,
including colon 201, and a system 401 for performing an image
guided medical procedure. FIG. 4A illustrates candidate lesions
205a-205f and region of interest 207. Flexible endoscope 403, which
is part of system 401, is shown inserted into colon 201 via orifice
405. One of ordinary skill in the art will recognize that, while
the figures illustrate the invention as used in colonoscopy, these
applications are illustrative only, and applications of the systems
and methods described herein on other parts of the anatomy of a
patient are within the scope of the invention, including those with
additional, modified, and/or alternate system components. As such,
flexible endoscope 403 may comprise a colonoscope, a bronchoscope,
a ventricularscope, a cystoscope, a arthroscope, a duodenoscope, a
colposcope, a hysteroscope, a laparoscope; a laryngoscope, a
sigmoidoscope, a gastroscope, or other instrument.
[0064] According to one embodiment of the invention, a position
sensing system 407 is used during the endoscopic medical procedure.
As such, position sensing system 407 may be located near, on, or in
the patient. Position sensing system 407 is associated with its own
coordinate system 409 (i.e., a frame of reference intrinsic to
position sensing system 407). Position sensing system 407 is
capable of determining the position and orientation of a sensor
element attached to an instrument (e.g., endoscope 403) and
relaying that information to an attached control unit 411. Control
unit 411 may in turn be connected to a computer system 413 onto
which pre-operative images, intra-operative images, other images,
coordinates of the candidate lesions, centerline path points, most
likely path points, regions of interest, and/or other data 417 is
loaded. Computer system 413 may be associated with a display device
415, input devices (not shown), and/or other devices.
[0065] In one embodiment, control unit 411 may be attached directly
(e.g., via a wired connection) to a sensor element embedded in
endoscope 403 or other tracked instrument. In other embodiments,
control unit 411 may be in communication with the sensor element
via a wireless connection. In one embodiment, the sensor element
may comprise an electromagnetic sensor coil. In these embodiments
position-sensing system 407 may comprise an electromagnetic
position sensing system that is capable of determining the position
and orientation of the electromagnetic sensor coil and/or other
electromagnetic sensor coils. Other types of position sensing
systems may be used.
[0066] Referring back to FIG. 1, in an operation 107, the medical
procedure may begin by introducing an instrument into the anatomy
of the patient. For example, operation 107 may include inserting
endoscope 403 into colon 201 in a manner known in the art. In some
embodiments, this can be done by inserting endoscope 403 into
natural or artificially created orifice of the patient (e.g.
orifice 405).
[0067] In some types of standard endoscopy as known in the art, the
medical procedure may include fully inserting endoscope 403 into
the anatomy of interest of the patient and then slowly withdrawing
it from the anatomy while observing optically in all directions.
For example, in the case of colonoscopy, endoscope 403 may be fully
inserted, e.g., to caecum 419 and then withdrawn while optically
observing the interior of colon 201.
[0068] In some embodiments, once the endoscope is fully inserted in
the organ (or inserted to a desired depth), a guidewire, catheter,
biopsy device, diagnostic tool or other elongated instrument 421,
may be placed inside endoscope 403's working channel 423. In some
embodiments, the distal end of elongated instrument 421 is moved
through working channel 423 of endoscope 403 to or beyond a distal
end 425 of endoscope 403. In some embodiments, elongated instrument
421 may be placed beside the optical portion of endoscope 403.
[0069] In one embodiment, such as those illustrated in FIG. 4B,
elongated instrument 421 may be equipped with at least one sensor
element 429, which enables the determination of the position and/or
the orientation (in the frame of reference 409 of position sensing
system 407) of a specific part of elongated instrument 421 and
therefore the part of endoscope 403 in which the specific part of
elongated instrument 421 resides. In one embodiment, sensor element
429 may be placed at the tip of elongated instrument 421. For more
information regarding instruments equipped with sensor elements and
other information relevant to the invention, see U.S. patent
application Ser. No. 11/471,604, entitled "System, Method and
Apparatus for Navigated Therapy and Diagnosis, which is hereby
incorporated by reference herein in its entirety.
[0070] In some embodiments, one or more sensor elements may be
embedded in or attached to endoscope 403 itself. Sensor elements
embedded directly in endoscope 403 enable direct determination of
the position and orientation of the tip (i.e., distal end 425) of
endoscope (when at least one sensor element is located at or near
the tip of the endoscope) and potentially many points along
endoscope 403 (when multiple sensor elements are located along a
portion of the endoscope), and thus its "shape" within the anatomy
of the patient, in the frame of reference of position sensing
system 407. Sensor elements in endoscope 403 may be used instead
of, or in addition to, an elongated instrument 421 with one or more
sensor elements included therein.
[0071] In one embodiment, endoscope 403 is a flexible endoscope.
For example, endoscope 403 may comprise a colonoscope or other
endoscope designed to examine the digestive system. As discussed
herein, other types of endoscopes may be used. In some embodiments,
endoscope 403 can be replaced by an elongated member such as a
catheter that contains a working channel.
[0072] In some embodiments, wherein endoscope 403 and/or elongated
instrument 421 is visible to an imaging modality, supplementary or
"intra-operative" images of the anatomy of the patient may be taken
in an operation 109, with endoscope 403 inserted. The imaging
modality used may be considered a "secondary" or "intra-operative"
imaging modality relative to the imaging modality used to acquire
the pre-operative images, which may be considered a "primary" or
pre-operative imaging modality. In some embodiments, the primary
and secondary imaging modalities may be the same or similar. In
some embodiments, because the relative position of the patient and
the imaging modality used in imaging may differ from pre-operative
imaging and intra-operative imaging, the coordinate systems of the
pre-operative images and the intra-operative images may differ,
even when the imaging modalities are the same.
[0073] In some embodiments, as more complex imaging modalities
(e.g., CT or MR scans) may be difficult or unwieldy to use during
the endoscopic procedure, x-ray, fluoroscopic ultrasound, or other
easier to use imaging devices may be used for intra-operative
imaging. However, CT, MR, or other complex imaging may be used,
nonetheless.
[0074] The intra-operative imaging may be used to precisely
determine the location of the actual path of endoscope 403
following insertion. For example, in one embodiment, the actual
path of endoscope 403 can be obtained using two or more
fluoroscopic shots taken at different angles, a CT scan, or other
images taken following insertion of endoscope 403. This
intra-operative imaging may also be used to determine the location
of the lesions 205a-205f or other areas of interest relative to the
inserted endoscope.
[0075] In general, the intra-operative images may be obtained in a
new coordinate system belonging to the secondary imaging modality
(e.g., in a frame of reference relative to the secondary imaging
modality). The actual path of endoscope 403 determined using the
intra-operative images may, in one embodiment, be matched or
registered to coordinate system 209 of the pre-operative images on
which the candidate lesions 205a-205f or other items of interest
have been annotated. For example, in one embodiment, centerline
path 211 calculated above for endoscope 403 may differ from the
actual path taken by inserted endoscope 403 (i.e., the "true path"
of the endoscope). The true path of endoscope 403 becomes available
once the intra-operative imaging is performed and analyzed.
[0076] In some embodiments it is desirable to register or match the
coordinate system of position sensing system 407 to one or more of
the coordinate system belonging to the primary imaging modality
(e.g., coordinate system 209) and/or the coordinate system
belonging to the secondary imaging modality (not illustrated). One
way of facilitating this is by acquiring a plurality of points in
position sensor space (i.e., coordinate system 409--the frame of
reference intrinsic to position sensing system 407) and
mathematically matching them to the same points in image space of
the pre-operative images (i.e., coordinate system 209--the frame of
reference of the primary imaging modality). As such, in an
operation 111, data regarding a plurality of points in position
sensor space may be obtained using one or more sensor elements and
position sensing system 407.
[0077] Acquisition of data in position sensor space can be
performed by obtaining the path of endoscope 403 by, for example,
sampling sensor elements placed in endoscope 403 using position
sensing system 407 to determine the path of endoscope 409. Another
method may involve dragging a tracked endoscope (e.g., endoscope
409) back through the anatomy of the patient (e.g., dragging it
back through colon 201) or elongated instrument 421 back through
working channel 423 of endoscope 403 (or the working channel of a
catheter or other instrument inserted into the patient's anatomy)
while position sensing system 407 gathers data points regarding the
position and/or orientation of the sensor elements on the tracked
instrument in coordinate system 409 of position sensing system 407.
While the frame of reference/coordinate system of position sensing
system 407 is referred to above as "position sensor space," this
frame of reference/coordinate system may also be referred to as the
"patient space." The collected data points in patient space may be
used is used to register the patient space to the pre-operative
image space of the primary imaging modality (pre-operative images),
the intra-operative image space of the secondary imaging modality
(intra-operative images), or both.
[0078] In some embodiments, instead of, or in addition to, using
the dragback method described above for obtaining data points in
patient space, individual identifiable locations in the anatomy of
the patient are sampled by touching or indicating them with the
tracked instrument or endoscope. In some embodiments, a tracked
instrument may be temporarily secured in endoscope 403 and not
dragged through working channel 423 of endoscope 403. In some
embodiments the tracked portion of the tracked instrument is placed
near the distal tip 425 of endoscope 403.
[0079] In some embodiments, it may be desirable to determine the
contortions that endoscope 421 has undergone without the use of
images. For example, a colonoscope frequently undergoes loops and
other deformations that affect a medical procedure being performed
using the colonocsope. Normally, it is difficult to determine these
deformations without imaging. If a tracked elongated member is
dragged through working channel 423 of endoscope 403, the locus of
points gathered as the position of sensor elements in the tracked
member are sampled prescribe a shape that is the same as the shape
of endoscope 403 within the anatomy of the patient. This
information may be used to assist in the medical procedure. In some
embodiments, only a single sensor element attached to a slidable
elongated member (e.g., a guidewire) is needed to determine this
shape. In some embodiments, multiple sensor elements may be fixed
or moved along endoscope 403 to determine its path. In some
embodiments, motion may be compensated for by using a dynamic
reference device such as, for example, a skin motion tracker, an
internally-placed catheter, or other dynamic referencing device.
Motion may also be compensated for using a gating device such as,
for example, an ECG (electroencephalogram), a respiratory gating
device, or other gating device.
[0080] In an operation 113, the image space path of inserted
endoscope 403 is resolved. As before, it is assumed that
registration can be performed using an elongated member or other
instrument and a distinction need not be made between endoscope 403
and elongated member 421 or other tracked instrument inserted
within the anatomy of the patient. In one embodiment, the image
space path of endoscope 403 may be "assumed" or "predicted" (i.e.
based on centerline path 211 or the "most likely path" 301
calculated using the pre-operative images that were also used to
identify the candidate lesions). This assumed image space path of
the endoscope may be used, but lacks a direct measure of the
endoscope in situ. In other embodiments, the image space path of
the endoscope may be based on the actual path of the inserted
endoscope observed in the intra-operative images. This "directly
measured" path may require a method expressing the coordinates of
this path in the same frame of reference as the candidate lesions
(e.g., registering the pre-operative images to the intra-operative
images).
[0081] In an operation 115, the resolved image space path of
endoscope 403 and the patient space path of endoscope 403 may be
registered. The two paths may be matched using an iterative closest
points (ICP), piecewise ICP, or similar algorithm. This enables a
registration matrix (or sequence of registration matrices) to be
generated. For additional information regarding registration
techniques and other information relevant to the invention, see
U.S. patent application Ser. No. 11/059,336 (U.S. Patent
Publication No. 20050182319), which is hereby incorporated by
reference herein in its entirety. In some embodiments, the start
and end points of the centerline locus of points may be adjusted so
that the centerline points correspond better to the sampled
path.
[0082] In some embodiments, registration may be accomplished using
other techniques as well, including the identification of
"fiducials" present in both preoperative images and identified
during the examination by for example touching them with a tracked
instrument to determine their location in position sensor space. If
at least 3 such points are co-located, a registration can be
performed using techniques such as the ICP above or simpler methods
such as singular valued decomposition. In some embodiments, the
fiducials can be naturally occurring landmarks, such as polyps, and
in other embodiments, they can be artificial landmarks such as
small balls, surgical staples, specially placed needles, or other
elements that may be visible in both the pre-operative images and
during optical examination with the endoscope. In some embodiments,
the dragback method described above may be used together with the
landmark based registration or other registration methods.
[0083] In some embodiments, the registration takes the form of a
rigid transformation matrix. In some embodiments, the registration
uses an affine transformation. In some embodiments, several
matrices are used at different places. In some embodiments,
weighted combinations of matrices are used.
[0084] If two representations of the endoscope's path from two
different coordinate systems are to resolve the image space path of
endoscope 403 (e.g., an assumed path calculated using pre-operative
image data and the actual path observed from the intra-operative
images), the two representations themselves must first be "matched"
or "registered." This registration may utilize 2D-3D or 3D-3D
co-registration techniques.
[0085] In some embodiments, endoscope 403 or other elongated
instrument may be equipped with additional sensor elements that can
act as dynamic referencing or tracking sensors, either with
multiple sensor elements placed along the length of endoscope 403
or sensor elements located at the most distal end (e.g., distal end
425) of endoscope 403. These will track gross patient movement or
movement the filed generator or other portion of position sensing
system 207 motion as long as endoscope 403 remains stationary.
[0086] In some embodiments, dynamic references (i.e., sensor
elements) can be placed into additional catheters, guidewires, or
instruments placed elsewhere in/on the patient that are not
affected by the exam. The purpose of these sensor elements is to
account for patient movement, including that occurring from
respiration, or other patient movement.
[0087] In some embodiments the dynamic reference may be externally
applied in the form of a skin patch or skin reference in which
trackable entities have been embedded. Information regarding skin
patch devices that can be used as dynamic references or for other
purposes in the context of the invention can be found in U.S.
patent application Ser. No. 11/271,899 (U.S. Patent Publication No.
20060173269), entitled "Integrated Skin-Mounted Multifunction
Device For Use in Image-Guided Surgery," which is hereby
incorporated by reference herein in its entirety.
[0088] In some embodiments the dynamic reference may be internally
applied using needles, catheters, guidewires, or other instruments.
In some embodiments, if, for example, skin patch fiducials or
internal fiducials are applied to the patient anatomy prior to
obtaining the pre-operative images, the fiducials may be used as a
"start point" for registration calculations that may ordinarily
take an extended amount of time to perform without a reasonable
guess of the correct transformation matrix. This is accomplished by
the skin patch, fiducials, or other registration objects having
features that are visible in the preoperative scan, where the
locations of these features are known relative to any sensor
elements used for dynamic referencing. Such features can take the
form of pathways (i.e. 2D or 3D shapes made from continuous paths
or shapes of an imagable material) or as fiducial clusters.
[0089] In some embodiments, the skin patch reference (if used) may
contain applied directional markings (e.g. printed on the surface
of the skin patch reference). These directional markings may point,
for example, toward the patient's left, right, head, and/or toe.
The positioning of these marks is used as a patient-centric
reference system. The patient-centric reference system is used to
reorient a display of the patient's anatomy being explored so as to
assist the hand-eye coordination of the surgeon such that the tools
moved on the display move according to the expectations of the
surgeon. In some forms of the display, displayed tools may move in
a non-intuitive way unless the display is rotated into the
patient-centric coordinate system.
[0090] In an operation 117, once registration has been performed,
the invention may include a display and navigation step in which
endoscope 403 is tracked in an attempt to locate the suspect
lesions with the assistance of the position sensor. In one
embodiment, this is facilitated by "parking" a tracked instrument
(e.g., elongated instrument 421) at the end of endoscope 403's
working channel (once any drag-back sampling or other registration
sampling that is required has been performed). In one embodiment,
endoscope 403 itself may also be tracked using sensor elements
attached to or integrated into endoscope 403, as described herein.
In one embodiment, an instrument can be inserted into the working
channel 423 of endoscope 403, and thus made to assume the shape of
working channel 423. This instrument is then made to become rigid
in the shape of endoscope 403 (e.g., through tensioning of a cable
such as, for example, that used in a "Greenberg Arm," or other
methods known in the art) and endoscope 403 is slid, along the
instrument, retracing the known path of the rigid path.
Alternatively, this type of instrument can be placed into the
anatomy prior to the registration and used as a guide for insertion
of endoscope 403.
[0091] As endoscope 403 and/or tracked instrument 421 (if used as
the means to track the endoscope) is moved through the anatomy to
inspect its interior, the position of endoscope 403 and/or tracked
instrument 421 may be sampled in the reference frame of position
sensing system 407. The locations and orientations determined by
position sensing system 407 are converted for the display of the
patient's anatomy by applying the registration transformation(s).
The location of endoscope 403 may then be indicated on the display.
In some embodiments, the display may be based on one or both of the
pre-operative or intra-operative images of the patient's anatomy.
Displays may include, for example, multiplanar reformats, oblique
reformatted views, 3D views, 3D perspective views, simplified
graphical "cockpit" style views, simplified maps, or other views.
Whenever one of the flagged locations (i.e., lesions or other items
of interest) is in the proximity of the tracked portion of
endoscope 403 or other instrument, the physician may be notified or
he or she will be able to determine from the images that he or she
is in proximity of the suspect lesion and can look for it.
[0092] In an operation 119, one or more of lesions 205a-205f or
other items of interest can then be destroyed, biopsied, or
otherwise treated, if detected. In one embodiment, tracked
elongated instrument 421 (if used in addition to endoscope 403) can
be removed from working channel 423 of endoscope 403, and a biopsy,
resection, or other treatment or detection device can be introduced
into working channel 423 of endoscope 403 (as the suspect will
likely be directly visible). Once investigated or treated, the
tracked elongated instrument 421 can be reintroduced into working
channel 423 of endoscope 403 and again parked at the end of
endoscope 403. In some embodiments, there may be enough space for
both tracked elongated instrument 421 and the treatment instrument.
In some embodiments, the treatment instrument itself may be
tracked.
[0093] In some embodiments, a tracked treatment instrument may be
introduced percutaneously or through an organ wall to perform a
biopsy, treatment, resection, or other treatment. In this way, for
example, an ablation or biopsy can be performed using a second
instrument. The second instrument can be operable either with
visual guidance or it can be positioned completely using the
electromagnetic guidance described herein. In some embodiments, an
imaging device such as a tracked endoscopic ultrasound can be
inserted into endoscope 403 to provide additional views. By
facilitating percutaneous treatment, candidate lesions on the
exterior of an organ being investigated can be accessed, which may
not be normally visible internally.
[0094] In some embodiments, a device containing trackable sensor
elements is not used in conjunction with the endoscope. Instead,
the device is used "blind", or for registration only. For example,
a steerable catheter might be inserted into colon 201. FIGS. 5A and
5B illustrate an example of a steerable catheter 500 that may be
used according to one embodiment of the invention. Steerable
catheter 500 may include a deflectable portion 501 with a steerable
tip 503. In some embodiments, steerable catheter 500 may include a
handle 505 with at least one deflection control knob or other
deflection control device 507. The shaft of steerable catheter 500
may include multiple lumens populated by different devices,
including a magnetic sensor element 509 with associated lead-wires
511 that exits catheter 500 and is connected to a control unit, in
some embodiments.
[0095] Section A-A details an embodiment of catheter 500 shown in
cross-section. The elongated body of steerable catheter 500 may
comprise a tube 513, which may be formed of any relatively soft
elastomeric material 515 (e.g., braid reinforced Fluorinated
Ethylene Propylene [FEP or Teflon.RTM.], polytetrafluoroethylene
[PTFE], polyether block amides such as, for example, Pebax.RTM. or
other material, some of which may be reinforced or include features
to render them visible in the imaging modality). Lumens within the
tube may include one or more steering wire channels such as
channels 517 or 519, a working channel 521, and a channel 523 for a
magnetic sensor element (e.g., element 509).
[0096] Other "blind" devices may include needles with tip tracking,
graspers, steerable forceps, or other elements. When used, the
"blind" device is positioned to targets within the anatomy entirely
using position sensing system 407 and the display.
[0097] In some embodiments, the invention provides for
registration-free navigation of an endoscope. In registration-free
navigation, sensor elements on a tracked guidewire or other tracked
device act simply as a distance measurement device to determine the
location of an endoscope relative to a known location. In this
embodiment, the relative location of all suspect lesions are
calculated relative to each other and landmarks within the anatomy.
As each is examined, the location is stored and the distance to the
next location of interest is calculated. In this way, the system is
self-correcting at each identified location along the path of the
endoscope as it is removed. This method may not require
registration to be performed prior to use.
[0098] FIG. 6 illustrates a process 600, an example of a process
for registration-free navigation. In an operation 601,
pre-operative images of the anatomy of interest (e.g., colon 201)
may be obtained. FIG. 7 an example wherein suspect lesions
701a-701f may be flagged on pre-operative images of colon 201
during a "virtual colonoscopy." This flagging/identification may
take place in an operation 603 an may be performed by physician, a
computer program, or both. The flagging/identification of operation
603 may include calculating the locations of the flagged suspect
lesions 701a-701f in a coordinate system 703, which is a frame of
reference intrinsic to the pre-operative images.
[0099] In an operation 605, the endoscope is inserted into colon
201. In an operation 607, a reference point 705 within colon 201 is
identified (for example, the ileocecal sphincter or appendiceal
orifice). In an operation 609, the path length of each of the
suspect lesions 701a-701f is identified relative to reference point
705 location along centerline 211 of colon 201. For example, for a
lesion 701a, path 707a is the length of the distance along
centerline 211 between reference point 705 (e.g., the appeniceal
orifice) and suspect lesion 701a. Likewise, path 709 is the length
of the distance along centerline 211 between reference point 705
(e.g., the appeniceal orifice) and suspect lesion 701b. Thus by
dragging the endoscope back and calculating the distance traversed
by the sensor attached to the endoscope, the location of the each
next suspect lesion can be determined.
[0100] In one embodiment, once the first lesion (i.e., 701a) is
encountered, the locations of the next lesions (i.e., 701b-701f)
may be calculated relative to it. For example, suspect lesion 701b
can be estimated to be located a distance 707b from suspect lesion
701a (or equivalently a distance 709 from reference point 705). In
general it may be more accurate to estimate the inter-lesion
distances (i.e. 707c, 707d, 707e, 707f), rather than the distance
between reference point 705 each successive lesion.
[0101] In one embodiment, the physician indicates each lesion 701
as it is encountered and in one embodiment, the lesions 707 and
other landmarks are weighted according to their distance from
reference point 705. As each lesion is encountered, the expected
distance to the next lesions is known from the pre-operative
images, since an estimate of that distance is available from the
images. Once the first lesion 701a or reference point 705 is
located, the endoscope is positioned at the next location (e.g.,
the next lesion--701b) according to the distance determined from
the pre-operative images (distance 707b from lesion 701a or
distance 709 from reference point 705). The distance that the
endoscope is moved from one lesion to the next is obtained from the
sensor elements in the endoscope. By measuring the distance that
the endoscope or a tracked instrument in the endoscope moved from a
first lesion to a second lesion, the location of the second lesion
can therefore be estimated from the pre-operative image estimates
without the need for registration.
[0102] In one embodiment, these measured distances are augmented
using shape information regarding the endoscope or other
instrument, as may be determined using a path determination method
such as those described herein. This shape information may be
helpful in more accurately determining the location of an area of
interest. In one embodiment, the suspect lesions can be used to
perform a registration. As each lesion is encountered, its position
is sampled using a tracked instrument and used to calculate a
transformation matrix. In some embodiments, only the nearest
candidate lesions to the immediate endoscope location can be used
to calculate a local registration, since they are most
representative of the local anatomy.
[0103] In one embodiment, at least one of the one or more points of
interest (e.g., location of lesions, polyps, or other points of
interest) within the anatomy of the patient that are identified in
image space, may be sampled in patient space and used for
registration of patient space coordinates to image space
coordinates. The locations of these points of interest may be used
bootstrap the registration, thereby enabling the system of the
invention to display the location of subsequent points of interest
not used in the registration (e.g., obtain position/location of a
first few lesions/polyps for registration, after which it becomes
"automatic" to locate other lesions/polyps due to the fact that the
registration has been performed). As such, the system will
automatically display the location of a tracked medical instrument
relative to the items of interest whose location has been sampled
as well as the items of interest whose location has not been
sampled. In one embodiment, the points of interest used to register
patient space to image space may be weighted relative to any points
of interest whose location is not sampled and used in a
registration.
[0104] In one embodiment, the invention provides a system for
performing and/or assisting in image-guided medical endoscopic
medical procedures. FIG. 4 illustrates a system 401, which is an
example of a system for performing and/or assisting in image-guided
medical endoscopic medical procedures. In one embodiment, system
401 may comprise control unit 411, a control application 427, a
tracked medical instrument (e.g., endoscope 403), position sensing
system 407, display device 415, and/or other elements.
[0105] In one embodiment, control unit 411 may be operatively
connected to or include one or more special purpose or general
purpose computers 413 and/or other devices having processors cable
of responding to and executing instructions in a defined manner.
Control unit 411 and/or computer system 413 may include, be
associated with, and/or be in operative communication with a memory
device that stores any data necessary for the performing the
features or functions of the invention such as, for example, image
data, position data, orientation data, coordinate data,
transformation matrices, and/or other data (e.g., data 417).
Control unit 411 and/or computer system 413 may also include, run,
and/or support control application 427 comprising one or more
software modules for directing and performing one or more data
reception, transmission, data processing, and/or other data
manipulation operations according to the features and functions of
the invention. Other software modules supporting or enabling the
various features and functions of the invention may be used.
[0106] In some embodiments, the tracked medical instrument may
include endoscope 403 that is equipped with at least one working
channel, optics for viewing the anatomy present at the distal tip
of the endoscope, one or more trackable sensor elements, and/or
other elements. The position and/or orientation of the one or more
sensor elements may be determined/monitored by position sensing
system 407. Position sensing system 407 may be in communication
with control unit 411 and/or computer system 413 and may provide
sampled position coordinates and orientation information of the one
or more sensor elements to control unit 411 and/or computer system
413. An example of position sensing system 407 includes an
electromagnetic position sensing system used with electromagnetic
sensor elements.
[0107] In some embodiments, the tracked medical instrument may
include an untracked endoscope or other instrument used in
conjunction with a tracked catheter, tracked guidewire, tracked
treatment device, and/or other tracked instrument (e.g., elongated
instrument 421). In some embodiments, system 401 may not include an
endoscope, but may include one or more tracked devices that do not
include the optics typically associated with an endoscope.
[0108] The system of the invention may also include display device
415 that displays images used in the system and methods of the
invention such as, pre-operative images of the anatomy of a patient
(including one or more items of interest), intra-operative images
of the anatomy of the patient (including an inserted medical
instrument and the one or more items of interest), real-time or
near-real-time images displaying motion of the tracked instrument
relative to the one or more items of interest within the anatomy of
the patient, and/or other images or data. In some embodiments,
display device 415 may include a computer monitor, a television
monitor, a touch screen, a cathode-ray tube, an LCD display device,
and/or other display device.
[0109] In some embodiments, system 401 may include other elements
(e.g., input/output ports, additional devices, additional
modules/software). Those having skill in the art will appreciate
that the invention described herein may work with various system
configurations. Accordingly, more or less of the aforementioned
system components may be used and/or combined in various
embodiments. Accordingly, more or less of the aforementioned
operations of the methods and processes of the invention may be
used, and/or may be performed in varying orders. As would also be
appreciated, the functionalities described herein may be
implemented in various combinations of hardware and/or firmware, in
addition to, or instead of, software.
[0110] Other embodiments, uses and advantages of the invention will
be apparent to those skilled in the art from consideration of the
specification and practice of the invention disclosed herein. The
specification should be considered exemplary only, and the scope of
the invention is accordingly intended to be limited only by the
following claims.
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