U.S. patent application number 17/195482 was filed with the patent office on 2021-12-30 for anatomical model generation.
The applicant listed for this patent is Affera, Inc.. Invention is credited to Doron Harlev, Geoffrey Peter Wright.
Application Number | 20210401503 17/195482 |
Document ID | / |
Family ID | 1000005830317 |
Filed Date | 2021-12-30 |
United States Patent
Application |
20210401503 |
Kind Code |
A1 |
Harlev; Doron ; et
al. |
December 30, 2021 |
ANATOMICAL MODEL GENERATION
Abstract
Devices, systems, and methods of the present disclosure are
directed to generating three-dimensional surface representations of
an anatomic structure such as a heart cavity. More specifically, a
three-dimensional surface representation of the anatomic structure
is constrained relative to one or more anchor portions
corresponding to received input regarding the location of anatomic
features of the anatomic structure. The resulting three-dimensional
surface representation includes salient features of the anatomic
structure and, therefore, can be useful as visualization tool
during any of various different medical procedures, including, for
example, cardiac ablation.
Inventors: |
Harlev; Doron; (Brookline,
MA) ; Wright; Geoffrey Peter; (Winchester,
MA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Affera, Inc. |
Watertown |
MA |
US |
|
|
Family ID: |
1000005830317 |
Appl. No.: |
17/195482 |
Filed: |
March 8, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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16945785 |
Jul 31, 2020 |
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17195482 |
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16525363 |
Jul 29, 2019 |
10765481 |
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16945785 |
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15592815 |
May 11, 2017 |
10376320 |
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16525363 |
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62334577 |
May 11, 2016 |
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62338105 |
May 18, 2016 |
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62393876 |
Sep 13, 2016 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61B 2018/00642
20130101; A61B 5/742 20130101; G06T 2219/004 20130101; A61B
2034/2051 20160201; G06T 17/20 20130101; A61B 2034/105 20160201;
G06T 17/00 20130101; A61B 2018/00839 20130101; A61B 2034/104
20160201; G16H 50/50 20180101; A61B 5/6843 20130101; A61B
2018/00875 20130101; G06T 19/20 20130101; A61B 2034/2063 20160201;
A61B 2090/064 20160201; A61B 5/062 20130101; A61B 18/1492 20130101;
A61B 34/20 20160201; G06T 2200/24 20130101; A61B 34/10 20160201;
A61B 5/283 20210101; A61B 5/063 20130101; A61B 34/25 20160201; A61B
8/12 20130101; G06T 2210/41 20130101 |
International
Class: |
A61B 34/10 20060101
A61B034/10; A61B 5/00 20060101 A61B005/00; G06T 17/00 20060101
G06T017/00; G16H 50/50 20060101 G16H050/50; A61B 34/20 20060101
A61B034/20; A61B 34/00 20060101 A61B034/00; A61B 18/14 20060101
A61B018/14; G06T 17/20 20060101 G06T017/20; G06T 19/20 20060101
G06T019/20 |
Claims
1. A method comprising: receiving a plurality of location signals,
each received location signal indicative of a respective location
of a medical device in an anatomic structure of a patient; forming
a three-dimensional data structure representing locations, within
the anatomic structure, visited by the medical device at the
locations corresponding to the plurality of location signals;
receiving one or more anchor portions representing locations
relative to the anatomic structure; and generating a
three-dimensional surface representation of the anatomic structure
of the patient, the three-dimensional surface representation of the
anatomic structure of the patient constrained relative to the one
or more anchor portions and to contain at least a portion of the
three-dimensional data structure.
2. The method of claim 1, further comprising displaying, on a
graphical user interface, at least one of a two-dimensional
projection of the three-dimensional data structure, the one or more
anchor portions, and a two-dimensional projection of the
three-dimensional surface representation.
3. The method of claim 1, wherein receiving the one or more anchor
portions representing locations relative to the anatomic structure
includes receiving, from one or more sensors disposed on the
medical device, a signal indicative of contact between the medical
device and tissue of the anatomic structure.
4. The method of claim 3, wherein the signal indicative of contact
is indicative of a blood-tissue boundary of the anatomic structure
of the patient.
5. The method of claim 3, wherein the signal indicative of contact
includes one or more of: a change in impedance detected by one or
more electrodes of the medical device, a force detected by a force
sensor of the medical device, an ultrasound signal of an ultrasound
sensor of the medical device, a deformation of at least a portion
of the medical device, and an amplitude derived from an electrogram
detected by one or more electrodes of the medical device.
6. The method of claim 1, wherein receiving the one or more anchor
portions includes receiving an input command from a user.
7. The method of claim 1, wherein receiving the one or more anchor
portions includes identifying a subset of the three-dimensional
data structure.
8. The method of claim 1, wherein receiving the one or more anchor
portions includes receiving a respective confidence level
associated each of the one or more anchor portions, and
constraining the three-dimensional surface representation relative
to the one or more anchor portions is based on the respective
confidence level associated with each of the one or more anchor
portions.
9. The method of claim 1, further comprising representing, on a
graphical user interface, the one or more anchor portions as
annotations on the three-dimensional surface representation of the
anatomic structure.
10. The method of claim 1, further comprising representing, on a
graphical user interface, the one or more anchor portions as
annotations on the three-dimensional data structure.
11. The method of claim 1, further comprising determining whether
the one or more anchor portions have been modified and, based on
whether the one or more anchor portions have been modified,
repeating the generating step.
12. The method of claim 11, wherein determining whether the one or
more anchor portions have been modified includes determining
whether one or more of previously identified anchor portions have
been removed.
13. The method of claim 1, wherein the three-dimensional surface
representation of the anatomic structure is a continuous mesh.
14. A method comprising: forming a three-dimensional data structure
based on received locations of a tip section of a cardiac catheter
in a heart cavity of a patient; receiving one or more anchor
portions representing locations relative to the heart cavity; and
generating a three-dimensional surface representation of the heart
cavity of the patient, the surface representation of the heart
cavity of the patient constrained relative to the anchor portions
and to contain at least a portion of the three-dimensional data
structure.
15. The method of claim 14, further comprising displaying, on a
graphical user interface, at least one of a two-dimensional
projection of the three-dimensional data structure, the one or more
anchor portions, and a two-dimensional projection of the generated
three-dimensional surface representation.
16. The method of claim 14, wherein receiving the one or more
anchor portions on the three-dimensional data structure includes
receiving one or more location signals indicative of one or more
respective locations of the cardiac catheter in the heart
cavity.
17. The method of claim 14, wherein receiving the one or more
anchor portions includes receiving, from a sensor disposed on the
cardiac catheter, a signal indicative of a blood-tissue boundary of
the heart cavity of the patient.
18. The method of claim 17, wherein the signal indicative of the
blood-tissue boundary includes one or more of: a change in
impedance detected by one or more electrodes of the cardiac
catheter, a force detected by a force sensor of the cardiac
catheter, an ultrasound signal of an ultrasound sensor of the
cardiac catheter, and a deformation of at least a portion of the
cardiac catheter, and an amplitude derived from an electrogram
detected by one or more electrodes of the cardiac catheter.
19. The method of claim 14, wherein receiving the one or more
anchor portions on the three-dimensional data structure includes
receiving an input command from a user interface.
20. A non-transitory, computer-readable storage medium having
stored thereon computer executable instructions for causing one or
more processors to: receive a plurality of location signals, each
received location signal indicative of a respective location of a
medical device in an anatomic structure of a patient; form a
three-dimensional data structure representing volumes, within the
anatomic structure, occupied by the medical device at the locations
corresponding to the plurality of location signals; receive one or
more anchor portions representing locations relative to the
anatomic structure; and generate a three-dimensional surface
representation of the anatomic structure of the patient, the
three-dimensional surface representation of the anatomic structure
of the patient constrained relative to the one or more anchor
portions and containing at least a portion of the three-dimensional
data structure.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. application Ser.
No. 16/945,785, filed Jul. 31, 2020, now pending, which is a
continuation of U.S. application Ser. No. 16/525,363, filed Jul.
29, 2019, now U.S. Pat. No. 10,765,481, which is a continuation of
U.S. application Ser. No. 15/592,815, filed May 11, 2017, now U.S.
Pat. No. 10,376,320, which claims the benefit under 35 U.S.C.
.sctn. 119(e) of U.S. Prov. App. No. 62/334,577, filed May 11,
2016, U.S. Prov. App. No. 62/338,105, filed May 18, 2016, and U.S.
Prov. App. No. 62/393,876, filed Sep. 13, 2016, with the entire
contents of each of these applications hereby incorporated herein
by reference.
BACKGROUND
[0002] Three-dimensional models can be used to assist in the
placement or use of a device when such placement or use is not
easily observable or practical. For example, in medical procedures,
three-dimensional models are used to assist in the placement and
use of medical devices for diagnosis or treatment of patients. An
example of such a medical procedure carried out with the assistance
of a three-dimensional model is the use of a catheter to deliver
radio frequency ("RF") ablation to form lesions that interrupt
abnormal conduction in cardiac tissue, thus terminating certain
arrhythmias in the heart.
SUMMARY
[0003] The present disclosure is directed to devices, systems, and
methods of generating an accurate three-dimensional model of an
anatomic structure of a patient to facilitate, for example, moving
a medical device through the anatomic structure during a medical
procedure in which the three-dimensional model is used to visualize
the medical device in the anatomic structure. For example, the
systems and methods of the present disclosure can be used to
generate a three-dimensional model based on input (e.g., from a
physician) of anchor portions corresponding to the position of
anatomic features of the anatomic structure. As a more specific
example, the systems and methods of the present disclosure can be
used to generate a three-dimensional surface representation of the
anatomic structure, with the three-dimensional surface
representation constrained relative to one or more anchor portions
identified on a three-dimensional data structure. Because the
constraint imposed by the one or more anchor portions can change
the shape of the three-dimensional surface representation and,
thus, can have the appearance of changing the position of tissue in
a visual representation of the three-dimensional surface
representation, the constraint imposed by the anchor portions is
sometimes referred to herein as "pinch." More generally, the
devices, systems, and methods of the present disclosure can provide
a physician with a greater amount of control over a
three-dimensional model of an anatomic structure and, additionally
or alternatively, can represent salient features of the anatomic
structure in greater detail than is typically achievable in a
three-dimensional model built based solely on an incomplete or
uncertain data set of known locations of a medical device in an
anatomic structure.
[0004] According to one aspect, a method includes receiving a
plurality of location signals, each received location signal
indicative of a respective location of a medical device in an
anatomic structure of a patient, forming a three-dimensional data
structure representing locations, within the anatomic structure,
visited by the medical device at the locations corresponding to the
plurality of location signals, receiving one or more anchor
portions representing locations relative to the anatomic structure,
and generating a three-dimensional surface representation of the
anatomic structure of the patient, the three-dimensional surface
representation of the anatomic structure of the patient constrained
relative to the one or more anchor portions and to contain at least
a portion of the three-dimensional data structure.
[0005] In certain implementations, the method can further include
displaying, on a graphical user interface, at least one of a
two-dimensional projection of the three-dimensional data structure,
the one or more anchor portions, and a two-dimensional projection
of the three-dimensional surface representation.
[0006] In some implementations, receiving the one or more anchor
portions representing locations relative to the anatomic structure
can include receiving, from one or more sensors disposed on the
medical device, a signal indicative of contact between the medical
device and tissue of the anatomic structure. The signal indicative
of contact can be, for example, indicative of a blood-tissue
boundary of the anatomic structure of the patient. Additionally, or
alternatively, the signal indicative of contact can include one or
more of: a change in impedance detected by one or more electrodes
of the medical device, a force detected by a force sensor of the
medical device, an ultrasound signal of an ultrasound sensor of the
medical device, a deformation of at least a portion of the medical
device, and an amplitude derived from an electrogram detected by
one or more electrodes of the medical device.
[0007] In certain implementations, receiving the one or more anchor
portions can include receiving an input command from a user.
[0008] In some implementations, receiving the one or more anchor
portions can include identifying a subset of the three-dimensional
data structure.
[0009] In certain implementations, receiving the one or more anchor
portions can include receiving a respective confidence level
associated each of the one or more anchor portions, and
constraining the three-dimensional surface representation relative
to the one or more anchor portions is based on the respective
confidence level associated with each of the one or more anchor
portions.
[0010] In some implementations, the method can further include
representing, on a graphical user interface, the one or more anchor
portions as annotations on the three-dimensional surface
representation of the anatomic structure.
[0011] In certain implementations, the method can further include
representing, on a graphical user interface, the one or more anchor
portions as annotations on the three-dimensional data
structure.
[0012] In some implementations, the method can further include
determining whether the one or more anchor portions have been
modified and, based on whether the one or more anchor portions have
been modified, repeating the generating step. Determining whether
the one or more anchor portions have been modified can include, for
example, determining whether one or more of previously identified
anchor portions have been removed.
[0013] In certain implementations, the three-dimensional surface
representation of the anatomic structure can be a continuous
mesh.
[0014] According to another aspect, a method includes forming a
three-dimensional data structure based on received locations of a
tip section of a cardiac catheter in a heart cavity of a patient,
receiving one or more anchor portions representing locations
relative to the heart cavity, and generating a three-dimensional
surface representation of the heart cavity of the patient, the
surface representation of the heart cavity of the patient
constrained relative to the anchor portions and to contain at least
a portion of the three-dimensional data structure.
[0015] In some implementations, the method can further include
displaying, on a graphical user interface, at least one of a
two-dimensional projection of the three-dimensional data structure,
the one or more anchor portions, and a two-dimensional projection
of the generated three-dimensional surface representation.
[0016] In certain implementations, receiving the one or more anchor
portions on the three-dimensional data structure can include
receiving one or more location signals indicative of one or more
respective locations of the cardiac catheter in the heart
cavity.
[0017] In some implementations, receiving the one or more anchor
portions can include receiving, from a sensor disposed on the
cardiac catheter, a signal indicative of a blood-tissue boundary of
the heart cavity of the patient. The signal corresponding to the
blood-tissue boundary can include one or more of: a change in
impedance detected by one or more electrodes of the cardiac
catheter, a force detected by a force sensor of the cardiac
catheter, an ultrasound signal of an ultrasound sensor of the
cardiac catheter, and a deformation of at least a portion of the
cardiac catheter, and an amplitude derived from an electrogram
detected by one or more electrodes of the cardiac catheter.
[0018] In certain implementations, receiving the one or more anchor
portions on the three-dimensional data structure can include
receiving an input command from a user interface.
[0019] In some implementations, the method can further include
representing, on a graphical user interface, the one or more anchor
portions as annotations on the three-dimensional surface
representation of the heart cavity.
[0020] According to still another aspect, a non-transitory,
computer-readable storage medium has stored thereon computer
executable instructions for causing one or more processors to:
receive a plurality of location signals, each received location
signal indicative of a respective location of a medical device in
an anatomic structure of a patient; form a three-dimensional data
structure representing volumes, within the anatomic structure,
occupied by the medical device at the locations corresponding to
the plurality of location signals; receive one or more anchor
portions representing locations relative to the anatomic structure;
and generate a three-dimensional surface representation of the
anatomic structure of the patient, the three-dimensional surface
representation of the anatomic structure of the patient constrained
relative to the one or more anchor portions and containing at least
a portion of the three-dimensional data structure.
[0021] Implementations can include one or more of the following
advantages.
[0022] In certain implementations, a three-dimensional surface
representation of an anatomic structure can be based on one or more
anchor portions. For example, the three-dimensional surface
representation of the anatomic structure can be constrained to pass
near the one or more anchor portions and/or to pass near a fixed
position relative to the one or more anchor portions. By imposing
such conditions, the three-dimensional surface representation can
accurately represent an anatomic structure such as, for example, an
anatomic structure with local concavities along a generally convex
shape. Such accurate representation can be particularly
advantageous for proper manipulation of a catheter for the accurate
placement of lesions in the heart, such as placement of lesions in
the carina between pulmonary veins. Further, constraining the
three-dimensional representation relative to one or more anchor
portions can facilitate generating an accurate representation of
the anatomic structure based on relatively few data points (e.g.,
an incomplete or uncertain data set) while still providing a useful
representation of salient anatomic features of the anatomic
structure. Thus, for example, constraining the three-dimensional
surface representation relative to one or more anchor portions can
facilitate building a useful depiction of the anatomic structure in
less time than would ordinarily be required to achieve the same
level of detail in a model built based on catheter position alone.
Additionally, or alternatively, constraining the three-dimensional
surface representation relative to one or more anchor portions can
facilitate shaping the three-dimensional surface representation
independently of other parameters used to form the
three-dimensional surface representation (e.g., tightness of a
surface mesh).
[0023] In some implementations, one or more anchor portions can be
based on feedback from one or more sensors on a medical device
within an anatomic structure. In certain implementations, the one
or more anchor portions can be based on input from the physician.
Thus, for example, the one or more anchor portions can be based on
a useful combination of physician input and feedback from one or
more sensors of a medical device positioned within the anatomic
structure. Such a combination can be useful for providing insights
into the shape of the anatomic structure, while providing the
physician with the ability to verify and, if necessary, override
feedback from the one or more sensors.
[0024] Other aspects, features, and advantages will be apparent
from the description and drawings, and from the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] FIG. 1 is a schematic representation of a system during a
medical procedure.
[0026] FIG. 2 is a perspective view of an exemplary medical device
of the system of FIG. 1.
[0027] FIG. 3 is a schematic representation of a tip section of the
medical device of FIG. 2 shown in an anatomic structure.
[0028] FIG. 4 is a schematic depiction of a projection of a
three-dimensional data structure and a three-dimensional surface
representation of the anatomic structure projected to a graphical
user interface of the system of FIG. 1.
[0029] FIG. 5A is a schematic representation of a surface of the
anatomic structure having superimposed thereon a point cloud,
corresponding to known locations of a medical device in an anatomic
structure, and a volumetrically smoothed three-dimensional surface
representation with a high degree of volumetric smoothing.
[0030] FIG. 5B is a schematic representation of a surface of the
anatomic structure having superimposed thereon the point cloud of
FIG. 5A and a three-dimensional surface representation with a low
degree of volumetric smoothing.
[0031] FIG. 5C is a schematic representation of a surface of the
anatomic structure having superimposed thereon the point cloud of
FIG. 5A and a three-dimensional surface representation constrained
relative to one or more anchor portions.
[0032] FIG. 6A is a schematic depiction of a three-dimensional data
structure of FIG. 4 and an unconstrained three-dimensional surface
representation displayed on the graphical user interface of the
system of FIG. 1.
[0033] FIG. 6B is a schematic depiction of the three-dimensional
data structure and the unconstrained three-dimensional surface
representation of FIG. 6A displayed on the graphical user interface
of the system of FIG. 1 with an anchor portion identified on the
three-dimensional data structure.
[0034] FIG. 6C is a schematic depiction of the three-dimensional
data structure of FIG. 6A and a three-dimensional surface
representation constrained relative to the anchor portion of FIG.
6B, the three-dimensional data structure and the three-dimensional
surface representation displayed on the graphical user interface of
the system of FIG. 1, with the three-dimensional surface
representation surface smoothed.
[0035] FIG. 6D is a schematic depiction of the three-dimensional
surface representation of FIG. 6C displayed on the graphical user
interface of the system of FIG. 1.
[0036] FIG. 7 is a flowchart of an exemplary method of representing
a surface of an anatomic structure.
[0037] FIG. 8 is a flowchart of an exemplary method of representing
a surface of a heart cavity of a patient.
[0038] Like reference symbols in the various drawings indicate like
elements.
DETAILED DESCRIPTION
[0039] The present disclosure is generally directed to devices,
systems, and methods of generating a three-dimensional surface
representation of an anatomic structure of a patient. More
specifically, the three-dimensional surface representation can
accurately represent local anatomic features of the anatomic
structure, while being based on an incomplete or uncertain data
set, by constraining (e.g., pinching) the three-dimensional surface
representation relative to the one or more anchor portions. For at
least this reason, the three-dimensional surface representations
generated according to the devices, systems and methods of the
present disclosure can be generated efficiently and, in use, can be
useful for facilitating visualization of a position of a medical
device (e.g., a catheter) during a medical procedure (e.g.,
diagnosis and/or treatment) being performed on the anatomic
structure.
[0040] It should be appreciated that, unless otherwise specified or
made clear from the context, the systems and methods of the present
disclosure can be used for any of various different medical
procedures, such as procedures performed on a hollow anatomic
structure of a patient, and, more specifically, in a hollow
anatomic structure, in which direct visual access to the medical
procedure is impractical and/or is improved by the use of a model
of the anatomic structure. Thus, for example, the systems and
methods of the present disclosure can be used to facilitate
visualization of a catheter inserted into a heart cavity as part of
a medical treatment associated with diagnosis, treatment, or both
of a cardiac condition (e.g., cardiac arrhythmia). Additionally, or
alternatively, the systems and methods of the present disclosure
can be used in one or more medical procedures associated with
interventional pulmonology, brain surgery, or sinus surgery (e.g.,
sinuplasty).
[0041] As used herein, the term "physician" shall be understood to
include any type of medical personnel who may be performing or
assisting a medical procedure and, thus, is inclusive of a doctor,
a nurse, a medical technician, other similar personnel, and any
combination thereof. Additionally, or alternatively, as used
herein, the term "medical procedure" shall be understood to include
any manner and form of diagnosis, treatment, or both, inclusive of
any preparation activities associated with such diagnosis,
treatment, or both. Thus, for example, the term "medical procedure"
shall be understood to be inclusive of any manner and form of
movement or positioning of a medical device in an anatomic
chamber.
[0042] As used herein, the term "patient" should be considered to
include any mammal, including a human, upon which a medical
procedure is being performed.
[0043] FIG. 1 is a schematic representation of a system 100 during
a medical procedure performed in an anatomic structure of a patient
102. The system 100 can include a medical device 104 connected, via
an extension cable 106, to an interface unit 108. The interface
unit 108 can include a processing unit 109 (e.g., one or more
processors), a graphical user interface 110, and a storage medium
111. The graphical user interface 110 and the storage medium 111
can be in electrical communication (e.g., wired communication,
wireless communication, or both) with the processing unit 109.
[0044] In use, the medical device 104 can be moved within the
anatomic structure (e.g., as part of a medical procedure) such that
the processing unit 109 can receive a plurality of location signals
of the medical device 104 in the anatomic structure. As described
in greater detail below, the processing unit 109 can construct a
three-dimensional surface representation of the anatomic structure
based on a three-dimensional data structure representing locations,
within the anatomic structure, visited by the medical device 104.
To the extent the medical device 104 has not visited each location
within the anatomic structure, a corresponding three-dimensional
data structure can be an incomplete or uncertain data set. To
account for such an incomplete or uncertain data set, it can be
useful to volumetrically smooth the three-dimensional surface
representation generated based on the three-dimensional data
structure. As a result of such volumetric smoothing, however,
certain portions of the three-dimensional surface representation
may not pass close to the visited locations of the medical device
104 along some areas of the three-dimensional data structure. To
account for such unintended distortions of the three-dimensional
surface representation, as also described in greater detail below,
the processing unit 109 can receive one or more inputs
corresponding to one or more anchor portions for advantageously
constraining a three-dimensional surface representation of the
anatomic structure. For example, without modifying other parameters
of a surface mesh, the three-dimensional surface representation can
be constrained to include details of the anatomic structure that
would not otherwise be represented in a three-dimensional surface
representation based on catheter location alone.
[0045] In general, the three-dimensional surface representation of
the anatomic structure formed using system 100 according to any one
or more of the methods described herein can be shown on the
graphical user interface 110, and the three-dimensional surface
representation can be used to facilitate performance of a medical
procedure by a physician. For example, as described in greater
detail below, the three-dimensional surface representation of the
anatomic structure and the position of the medical device 110 can
be shown on the graphical user interface 110 and used as a visual
guidance tool (e.g., as an analog) for movement of the medical
device 104 in the anatomic structure. It should be appreciated,
therefore, that the details provided in the three-dimensional
surface representation generated as described herein can facilitate
fine movement of the medical device 104 relative to the anatomic
structure. As an example, as compared to a three-dimensional
surface representation based on catheter position alone, the
three-dimensional surface representation generated according to any
one or more of the methods described herein can more accurately
represent anatomic features or landmarks that are useful for
positioning the medical device 104 relative to targeted tissue.
Further, or in the alternative, as compared to a three-dimensional
surface representation constructed solely from interpolation or
approximation between points in a data set of known positions of
the medical device 104 in an anatomic structure, the
three-dimensional surface representation generated according to any
one or more of the methods described herein is less likely to be
unintentionally distorted in areas in which there are significant
spatial gaps in position data of the medical device 104.
[0046] Referring now to FIGS. 1-2, the medical device 104 can be
any of various different medical devices known in the art for use
with respect to an anatomic structure and includes, therefore, any
manner and form of medical devices useful for diagnosis, treatment,
and combinations thereof. For the sake of explanation, and not by
way of limitation, the medical device 104 is described herein as a
catheter insertable into an anatomic structure. Thus, the medical
device 104 can include a handle 120, a shaft 122, and a tip section
124. The shaft 122 can include a proximal portion 126 secured to
the handle 120, and a distal portion 128 coupled to the tip section
124.
[0047] The tip section 124 generally includes any portion of the
medical device 104 that directly or indirectly engages tissue for
the purpose of treatment, diagnosis, or both and, therefore, can
include any one or more of all manner and type of contact and/or
non-contact interaction with tissue known in the art. For example,
the tip section 124 can include one or more of contact and
non-contact interaction with tissue in the form of energy
interaction (e.g., electrical energy, ultrasound energy, light
energy, cooling and any combinations thereof), chemical interaction
with tissue, or both. Thus, for example, the tip section 124 can
deliver energy (e.g., electrical energy) to tissue in the anatomic
structure as part of any number of medical procedures.
[0048] In certain implementations, it is desirable to deliver
energy (e.g., RF energy) from the tip section 124 to targeted
portions of tissue in the anatomic structure to ablate tissue at
some depth relative to a surface of the anatomic structure. In
implementations in which the anatomic structure is a heart cavity,
such ablations created by the tip section 124 along a surface of
the anatomic structure can, for example, treat cardiac arrhythmia
in patients with this condition. The effectiveness of the ablations
created using the tip section 124 in such a cardiac ablation
procedure, however, can be dependent upon the location of the
ablations. It should be appreciated, therefore, that accurate
representation of anatomic features or landmarks in the
three-dimensional surface representation used to guide placement of
the catheter can be advantageous for accurately delivering such
targeted ablation energy to tissue in cardiac ablation procedures
or other similar procedures in which there is a benefit derived
from targeted energy delivery.
[0049] The medical device 104 can include a sensor 125 disposed,
for example, along the tip section 124 and in electrical
communication with the interface unit 108 (e.g., in communication
with the processing unit 109). The sensor 125 can be any of various
different types of sensors suitable for sensing contact with tissue
of an anatomic structure and, therefore, can be useful for
providing feedback to the interface unit 108 regarding the location
of a blood-tissue boundary. In general, it should be understood
that any one or more forms of feedback provided by the sensor 125
can form the basis for generating anchor portions for constraining
a three-dimensional surface representation of the anatomic
structure. Examples of these forms of feedback provided by the
sensor 125 and useful as the basis for generating anchor portions
are described below. While the sensor 125 is described herein as a
single sensor for the sake of clarity of explanation, the sensor
125 can include an array of any one or more of the sensors
described herein, including, for example, any combination of the
sensors described herein.
[0050] As an example, the sensor 125 can include a sensing
electrode such that changes to an electrical signal measured
between the sensor 125 and another electrode (e.g., another sensor
carried on the tip section 124) can be detected as an indication of
the presence of viable tissue in contact with the sensor 125. As
used herein, viable tissue is tissue that conducts an electrical
signal and, thus, includes tissue that has not yet been ablated
(e.g., is not scar tissue) as well as tissue that is not otherwise
diseased such that conduction of the electrical signal is impaired.
The detection of viable tissue in contact with the sensor 125 can
include observation of the electrical signal by the physician.
Also, or in the alternative, the detection of viable tissue in
contact with the sensor can be based on a comparison of the
electrical signal relative to a predetermined threshold (e.g., for
a bipolar electrogram, a threshold of above about 0.1 mV). More
generally, any of the various different devices, systems, and
methods described herein can be advantageously used in combination
with detecting changes to an electrical signal measured between the
sensor 125 and another electrode to detect or confirm contact with
tissue.
[0051] Additionally, or alternatively, the sensor 125 can include a
force sensor to detect a magnitude and, optionally or additionally,
a direction of force exerted on the sensor 125 through contact with
a surface of the anatomic structure. Such a force sensor can
include any of various different force sensors responsive to
contact between the sensor 125 and tissue of the anatomic
structure. Such responsiveness can be independent, or at least
substantially independent, of whether or not the contacted tissue
is viable. Thus, for example, the sensor 125 can be a force sensor
including optical fibers, transmitting or sensing coils, and the
like, for sensing force. Contact between the sensor 125 and tissue
of the anatomic structure can result in an increase in measured
force. For example, a contact force greater than 5 g (e.g. greater
than 10 g) can be indicative of contact between the sensor 125 and
tissue. The measured force can, in addition or in the alternative,
be related to the degree of contact between the sensor 125 and the
tissue of the anatomic structure. Additionally, or alternatively,
contact between the sensor 125 and tissue of the anatomic structure
can result in a measured force in a direction normal to the tissue
at a point of contact.
[0052] As an additional or alternative example, the sensor 125 can
include an ultrasound sensor such that the sensor 125 can detect
features of an anatomic structure based on any of various different
ultrasound techniques that are known in the art. As a specific
example, the sensor 125 can include an ultrasound transducer such
that ultrasound reflections can be measured with respect to
distance along an axis of the sensor 125. Continuing with this
example, contact or proximity between the sensor 125 and tissue in
the anatomic structure can result in ultrasound reflections at
distances corresponding a distance between the sensor 125 and the
tissue.
[0053] As yet another additional or alternative example, the sensor
125 can include a deformation sensor to detect deformation (e.g.,
magnitude, direction, or both) of the tip section 124 as a result
of contact between the tip section 124 and a surface of the
anatomic structure. For example, the measured deformation can be a
substantially monotonic function of the degree of contact between
the sensor 125 and the tissue of the anatomic structure.
Additionally, or alternatively, contact between the sensor 125 and
tissue of the anatomic structure can result in deformation
primarily in a direction normal to the tissue at the point of
contact.
[0054] As yet another additional or alternative example, the sensor
125 can include an impedance sensor to detect a change in an
electrical impedance as a result of contact between the tip section
124 and tissue of the anatomic structure. For example, in some
implementations, contact between the sensor 125 and tissue in the
anatomic structure can be detected as an increase in a measured
impedance. Continuing with this example, an increase in a measured
impedance larger than the expected variation in the impedance when
the sensor 125 is not in contact with tissue (e.g. an increase
greater than 100 ohms) can be indicative of contact between the
sensor 125 and tissue in the anatomic structure. Additionally, or
alternatively, the measured impedance can be a substantially
monotonic function of the degree of contact between the sensor 125
and the tissue.
[0055] In addition to, or instead of, feedback provided by the
sensor 125, contact between the tip section 124 and tissue of the
anatomic structure can be based on one or more imaging modalities.
The use of one such imaging modality can include observation of one
or both of the tip section 124 and the shaft 122 by the physician
using fluoroscopy. An additional, or alternative, modality can
include observation of one or both of the tip section 124 and the
shaft by the physician using intracardiac ultrasound in
implementations in which the anatomic structure is a heart cavity.
In some instances, based on information determined according to any
one or more imaging modality, the physician can tag the location of
contact with tissue, and the tag can form a basis of the one or
more anchor portions near which the three-dimensional surface
representation is constrained to pass. Additionally, or
alternatively, information determined automatically from an image
can provide an indication of contact between the tip section 124
and tissue of the anatomic structure.
[0056] While contact with tissue that forms a basis for the anchor
portions can be based on feedback provided by sensors 125, it
should be appreciated that anchor portions can be additionally, or
alternatively, based on other types of feedback. For example,
anchor portions can be placed (e.g., through tags applied by the
physician) in locations in which a physician detects a resistance
to movement (e.g., rotation, articulation, advancement, or a
combination thereof), with resistance being indicative of contact
between the medical device 104 and the tissue.
[0057] The medical device 104 can further, or instead, include a
magnetic position sensor 130 along the distal portion 128 of the
shaft 122. It should be appreciated that the magnetic position
sensor 130 can be any of various magnetic position sensors well
known in the art and can be positioned at any point along the
distal portion 128. The magnetic position sensor 130 can, for
example, include one or more coils that detect signals emanating
from magnetic field generators. One or more coils for determining
position with five or six degrees of freedom can be used.
[0058] The magnetic field detected by the magnetic position sensor
130 can be used to determine the position of the distal portion 128
of the catheter shaft 122 according to one or more methods commonly
known in the art such as, for example, methods based on using a
sensor, such as the magnetic position sensor 130, to sense magnetic
fields indicative of the position of the magnetic position sensor
130 and using a look-up table to determine location of the magnetic
position sensor 130. Accordingly, because the tip section 124 is
coupled to the distal portion 128 of the shaft 122 in a known,
fixed relationship to the magnetic position sensor 130, the
magnetic position sensor 130 also provides the location of the tip
section 124. While the location of the tip section 124 is described
as being determined based on magnetic position sensing, other
position sensing methods can additionally or alternatively be used.
For example, the location of the tip section 124 can be
additionally, or alternatively, based on impedance, ultrasound,
and/or imaging (e.g., real time MRI or fluoroscopy).
[0059] Referring now to FIGS. 1-4, the tip section 124 of the
medical device 104 can be moved in an anatomic structure 132 (e.g.,
prior to application of an ablation treatment or other type of
treatment). If the tip section 124 of the medical device 104 is
movable in blood in the anatomic structure 132 and obstructed only
by a surface 133 of the anatomic cavity 132, the known positions of
the tip section 124 of the medical device 104 can be taken together
to provide an indication of the size and shape of a volume defined
by the surface 133 of the anatomic structure 132 and can form a
basis for a three-dimensional data structure 134 corresponding to a
volume defined by the anatomic structure 132. The three-dimensional
data structure 134 can include any of various different data
structures known in the art. As an example, the three-dimensional
data structure 134 can include an occupancy grid. As another
example, the three-dimensional data structure 134 can include an
indicator function. Additionally, or alternatively, the
three-dimensional data structure 134 can include a segmentation
mask. Further, or instead, the three-dimensional data structure 134
can include space carving.
[0060] Because it is often difficult or impractical to pass the tip
section 124 through each portion of the volume defined by the
surface 133 of the anatomic structure 132, the three-dimensional
data structure 134 may be an incomplete or uncertain data set. As
described in greater detail below, forming the three-dimensional
data structure 134 based on such an incomplete or uncertain data
set can have implications for accurately representing anatomic
features of the surface 133 of the anatomic structure 132. For
example, the three-dimensional data structure 134 can include a
probabilistic model as a function of location, and an incomplete or
uncertain data set of locations can result in regions of high
uncertainty in the probabilistic model. Also, or instead, the
three-dimensional data structure 134 can include a model with two
or more discrete states (e.g., a "blood" state, an "unknown" state,
a "tissue" state, a "boundary" state, and combinations thereof) as
a function of location, and an incomplete or uncertain data set of
locations can result in uncertain states (e.g. "unknown"
states).
[0061] While the three-dimensional data structure 134 can be based
on known positions of the tip section 124 of the medical device 104
in the anatomic structure 132, it should be appreciated that other
methods of determining the three-dimensional data structure 134 are
additionally or alternatively possible. For example, the
three-dimensional data structure 134 can be based on images of the
surface 133 of the anatomic structure 132 acquired prior to or
during the medical procedure, particularly in use cases in which
the images of the surface 133 of the anatomic structure 132 may not
be complete. Such images can correspond to any of various,
different imaging modalities including, for example, x-ray.
[0062] The three-dimensional data structure 134 can include, for
example, a three-dimensional grid of voxels 135. In general, it
should be appreciated that the three-dimensional grid of voxels 135
can be any one or more of various different types three-dimensional
grids well known in the art. By way of example, the
three-dimensional grid of voxels 135 can include one or more of an
occupancy grid and an occupancy field. By way of further,
non-exclusive example, the three-dimensional grid of voxels 135 can
include a volumetric grid representation.
[0063] Each voxel 135 can be a discrete element of volume.
Together, the voxels 135 can form the three-dimensional data
structure 134 which, in general, is a three-dimensional notational
space. As described in greater detail below, a three-dimensional
surface representation 136 can be formed in relation to the
three-dimensional data structure 134 such that the
three-dimensional surface representation 136 can represent the
surface 133 of the anatomic structure 132. In general, the
three-dimensional surface representation 136 can be any one or more
of the various different types well-known in the art and, thus, by
way of non-exclusive example can include any one or more of the
following: a "level set"; a "separating surface"; and an "implicit
surface".
[0064] In certain medical procedures, it can be impractical (e.g.,
due to time constraints) or impossible (e.g., due to shape) to
visit each location of the anatomic structure 132 with the tip
section 124. Accordingly, the three-dimensional data structure 134
and/or the three-dimensional surface representation 136 can be
necessarily based on certain inferences between data points. These
inferences, while serving as a useful expedient for generation of
the three-dimensional surface representation 136, can result in
discrepancies between the three-dimensional surface representation
136 and the surface 133 of the anatomic structure 132 upon which
the three-dimensional surface representation 136 is based. Such
discrepancies can, for example, result in one or more anatomic
features of the surface 133 of the anatomic structure 132 being
obscured, or at least distorted, in the resulting three-dimensional
surface representation 136.
[0065] The inferences used to form the three-dimensional surface
representation 136 can include any manner and form of volumetric
smoothing known in the art. For example, volumetric smoothing the
three-dimensional surface representation 136 can be based on
surface tension methods. As an additional or alternative example,
volumetric smoothing the three-dimensional surface representation
136 can be based on hole filling methods. As a further or
alternative example, volumetric smoothing the three-dimensional
surface representation 136 can be based on interpolation. As still
a further or alternative example, volumetric smoothing of the
three-dimensional surface representation 136 can be based on
ball-pivoting.
[0066] In general, discrepancies between the three-dimensional
surface representation 136 and the surface 133 of the anatomic
structure 132 can arise as a result of a trade-off between the
degree of volumetric smoothing used to form the three-dimensional
surface representation 136 and incompleteness or uncertainty of the
data set forming the three-dimensional data structure 134. That is,
it can be desirable to specify a low degree of volumetric smoothing
to achieve resolution of certain anatomic features in the
three-dimensional surface representation 136. Such resolution in
one area, however, can have the unintended consequence of creating
distortions in areas in which the data set is incomplete or
uncertain, with such incompleteness or uncertainty being common in
implementations in which the data set is based on locations in the
anatomic structure 132 visited by the tip section 124. For example,
the three-dimensional surface representation 136 can appear to
include numerous distortions (e.g., undulations or, more
specifically, invaginations) that are not representative of the
surface 133 of the anatomic structure 132 when a low degree of
volumetric smoothing is applied to an incomplete or uncertain data
set. However, increasing the amount of volumetric smoothing of the
three-dimensional surface representation 136 to remove such
distortions resulting from incompleteness or uncertainty of the
data set can have the unintended consequence of obscuring or
distorting certain anatomic features.
[0067] FIGS. 5A-5C are, collectively, a schematic depiction of a
generalized example of distortions that can occur as a result of
volumetric smoothing a three-dimensional surface representation
based solely on surface tension, hole filling, interpolation, ball
pivoting, or other similar implicit or explicit surface
reconstruction methods applied to an incomplete or uncertain data
set. In each of FIGS. 5A-5C, a point cloud 139 is shown
superimposed on the surface 133 of the anatomic structure 132 (FIG.
3). The point cloud 139 can correspond to, for example, known
locations of the tip section 124 of the medical device 104 in the
anatomic structure 132 (FIG. 3). As used, herein, the point cloud
139 should be understood to include any of various different point
clouds well known in the art of surface reconstruction. In general,
it is desirable to generate a volumetrically smoothed surface mesh
from the point cloud 139 to create a three-dimensional surface
representation that accurately represents the surface 133 of the
anatomic structure 132 (FIG. 3). However, as described in greater
detail below, distortions can occur when the point cloud 139 is an
incomplete or uncertain data set of an anatomic structure and it
is, nevertheless, desirable to represent accurately a geometric
feature of the surface 133.
[0068] FIG. 5A is a schematic representation of a three-dimensional
surface representation 136a of the point cloud 139, with the
three-dimensional surface representation 136a volumetrically
smoothed to a high degree. As shown in FIG. 5A, a high degree of
volumetric smoothing of the three-dimensional surface
representation 136a can result in significant deviations between
the three-dimensional surface representation 136a and the surface
133 (i.e., the intended shape). For example, with a high degree of
volumetric smoothing, the three-dimensional surface representation
136a can be based on an interpolation between data points of the
point cloud 139 that are not close to one another, and details of
the shape between the data points may be lost.
[0069] FIG. 5B is a schematic representation of a three-dimensional
surface representation 136b of the point cloud 139, with the
three-dimensional surface representation 136b smoothed to a low
degree of volumetric smoothing. Accordingly, the three-dimensional
surface representation 136b is based on interpolation between data
points of the point cloud 139 that are close to one another, as
compared to the interpolation associated with FIG. 5A. As shown in
FIG. 5B, the interpolation between data points in the point cloud
139 that are relatively close to one another can result in a shape
that shows features that are not actually present on the surface
133.
[0070] In general, it should be appreciated that inaccuracies, such
as those shown in FIG. 5A and FIG. 5B, can be particularly
prevalent in areas in which the surface 133 is represented by
relatively few data points of the point cloud 139. However, it is
often impractical or impossible to obtain a complete data set upon
which the three-dimensional surface representation 136a or 136b can
be based. For example, the time associated with obtaining such a
complete data set may be impermissibly long. As described in
greater detail below, a useful solution to this trade-off between
accuracy and challenges associated with data acquisition is to
constrain volumetric smoothing in areas in which the shape of the
surface 133 is known or known with some level of confidence.
[0071] Referring now to FIG. 5C, one or more anchor portions 142
can be added to the data set to identify one or more known
positions on the surface 133. As described in greater detail below,
the one or more anchor portions 142 can constrain the volumetric
smoothing of the three-dimensional surface representation 136c.
Because the three-dimensional surface representation 136c is
constrained relative to the one or more anchor portions 142,
distortions or other types of inaccuracies associated with a high
degree of volumetric smoothing (FIG. 5A) and a low degree of
volumetric smoothing (FIG. 5B) are less prevalent in the
three-dimensional surface representation 136c (FIG. 5C). More
generally, the three-dimensional surface representation 136c is a
more accurate representation of the surface 133 than would be
obtained without some form of constraint relative to the one or
more anchor portions 142, which represent corresponding positions
known, optionally with some degree of confidence, to lie on the
surface 133.
[0072] Referring again to FIGS. 1-4, the inaccuracies in the
three-dimensional surface representation 136 that can result from
volumetric smoothing can be particularly prevalent in locally
concave areas of the surface 133 along a generally convex portion
of the surface 133 of the anatomic structure 132. According to the
convention used herein, the concavity of the surface 133 of the
anatomic structure 132 is expressed with respect to the shape of a
blood-tissue boundary formed by the surface 133 of the anatomic
structure 132 (FIG. 3) around the blood. For example, as shown in
FIG. 3, the anatomic structure 132 can include carina 137a, 137b,
137c between anatomic elements 131a, 131b, 131c, 131d, 131e of the
anatomic structure 132. The surface 133 should be understood to be
locally concave along each carina 137a, 137b, 137c. In such
instances, volumetric smoothing the three-dimensional surface
representation 136 can result in an inaccurate depiction of the
surface 133 of the anatomic structure 132 in the region of the
carina 137a, 137b, 137c. Such an inaccurate depiction in the
three-dimensional surface representation 136 in the vicinity of one
or more of the carina 137a, 137b, 137c can be problematic, for
example, in instances in which it may be desirable to apply
lesions, and thus position accurately the tip section 124, in the
vicinity of one or more of the carina 137a, 137b, 137c. For
example, in FIG. 3, in instances in which the anatomic structure
132 is the left atrium, it may be desirable to apply lesions in the
carina 137c between the left superior pulmonary vein (LSPV) and the
left inferior pulmonary vein (LIPV), represented as 131d and 131e,
respectively. It should be appreciated that the anatomic structure
132 is depicted as the left atrium in FIG. 3 by way of example and
not limitation, and, thus, it should be appreciated that the number
and orientation of anatomic elements and corresponding carina (or
other similar locally concavities) present in the anatomic
structure 132 can depend on the type of anatomic structure.
[0073] To overcome the trade-off that can exist between global and
local resolution of the three-dimensional surface representation
136 as a result of incomplete or uncertain data regarding the
surface 133 of the anatomic structure 132, the present disclosure
is generally directed to constraining the three-dimensional surface
representation 136 according to one or more of the methods
described herein. For example, constraining the three-dimensional
surface representation 136 as described herein can facilitate
accurate representation of anatomic features of the surface 133 of
the anatomic structure 132 while allowing the three-dimensional
surface representation 136 to be generated efficiently (e.g., based
on an incomplete or uncertain data set of locations in the anatomic
structure 132).
[0074] The three-dimensional data structure 134 and the
three-dimensional surface representation 136 can be stored on the
storage medium 111, along with instructions executable by the
processing unit 109 to display the three-dimensional data structure
134, the three-dimensional surface representation 136, or both on
the graphical user interface 110, as described in greater detail
below. The instructions stored on the storage medium 111 and
executable by the processing unit 109 to display one or both of the
three-dimensional data structure 134 and the three-dimensional
surface representation can be, for example, an application built
using Visualization Toolkit, an open-source 3D computer graphics
toolkit, available at www.vtk.org.
[0075] FIG. 4 is a schematic representation of the
three-dimensional data structure 134 and the three-dimensional
surface representation 136 projected onto a viewing window 138 of
an image plane 140. While the three-dimensional data structure 134
and the three-dimensional surface representation 136 are described
as both being projected onto the viewing window 138, it should be
understood that the three-dimensional data structure 134 and the
three-dimensional surface representation 136 can be individually
projected to the viewing window 138. For example, it may be
desirable to project both the three-dimensional data structure 134
and the three-dimensional surface representation 136 onto the
viewing window 138 while the three-dimensional surface
representation 136 is being built. Additionally, or alternatively,
it may be desirable to project only the three-dimensional surface
representation 136 (e.g., by making the three-dimensional data
structure 134 at least partially translucent) onto the viewing
window 138 while the medical device 104 (FIG. 3) is being used to
diagnose and/or apply a treatment to the anatomic structure 132
(FIG. 3).
[0076] The graphical user interface 110 can be two-dimensional such
that the image plane 140 corresponds to a plane of the
two-dimensional display of the graphical user interface 110, and
the viewing window 138 corresponds to a field of view of the
two-dimensional display of the graphical user interface 110.
Accordingly, the image formed by projecting one or both of the
three-dimensional data structure 134 and the three-dimensional
surface representation 136 onto the viewing window 138 can be
displayed on the graphical user interface 110. As described in
greater detail below, a physician can, in certain instances,
interact with the projection of the three-dimensional data
structure 134 on the graphical user interface 110 to identify one
or more locations of anatomic features on the three-dimensional
data structure 134 such that the three-dimensional surface
representation 136, generated based on the three-dimensional data
structure 134, reflects these identified anatomic features.
[0077] FIGS. 6A-6D collectively represent a sequence of images
formed on the viewing window 138 and displayed on the graphical
user interface 110. The sequence illustrates, in general, the
generation of the three-dimensional surface representation 136.
[0078] Referring now to FIG. 6A, the three-dimensional data
structure 134 and an unconstrained three-dimensional surface
representation 136' can be displayed on the graphical user
interface 110. In FIG. 6A, the tricuspid valve, the inferior vena
cava, and the superior vena cava have each been cut in the
unconstrained three-dimensional surface representation 136' to
facilitate visualization. These cuts do not constrain the surface
extracted from the three-dimensional data structure 134.
[0079] The unconstrained three-dimensional surface representation
136' can represent a surface extracted from the three-dimensional
data structure 134 without specific input regarding the position of
anatomic features in the three-dimensional data structure 134.
Thus, in certain instances, anatomic features of the surface 133 of
the anatomic structure 132 (FIG. 3) may be obscured, distorted, or
otherwise misrepresented in the unconstrained three-dimensional
surface representation 136'. For example, the unconstrained
three-dimensional surface representation 136' may not accurately
represent anatomic features of the surface 133 of the anatomic
structure 132 (FIG. 3) if the three-dimensional data structure 134
is based on an incomplete or uncertain data set. That is, attempts
to form a surface mesh based on the three-dimensional data
structure 134 can result in an obscured and/or distorted
representation of the surface 133 of the anatomic structure 132
(FIG. 3), particularly along locally concave portions of the
surface 133 of the anatomic structure 132 (FIG. 3).
[0080] The volumetric smoothing required to create the
three-dimensional surface representation 136' based on an
incomplete or uncertain data set can obscure or distort areas that
are concave because the difference between missing data and an
actual concave region is often not discernible by a smoothing
algorithm, such as a surface tension algorithm, a hole filling
algorithm, an interpolation algorithm, a ball-pivoting algorithm,
or other similar algorithms. As a result, volumetric smoothing
required to form the three-dimensional surface representation 136'
based on an incomplete or uncertain data set can have the
unintended consequence of covering over concave regions.
Conversely, while it may be possible to capture aspects of local
detail by decreasing the degree of volumetric smoothing used to
form the three-dimensional surface representation 136', a low
degree of volumetric smoothing can create distortions along other
portions of the three-dimensional surface representation 136', such
as where the data set is incomplete or uncertain. Accordingly,
while the degree of volumetric smoothing can be adjusted to capture
aspects of local detail, such adjustments can have a negative
impact on the accuracy of the overall shape of the
three-dimensional surface representation 136'.
[0081] Referring now to FIGS. 2,3, and FIG. 6B, an advantageous
alternative to varying the degree of volumetric smoothing of the
surface mesh forming the three-dimensional surface representation
136' can include receiving identification of the one or more anchor
portions 142 on the three-dimensional data structure 134. Each
anchor portion 142 can correspond to a predetermined number of
voxels 135 of the three-dimensional data structure 134.
Additionally, or alternatively, each anchor portion 142 can
correspond to one or more nodes or points in the three-dimensional
data structure 134. In certain implementations, each anchor portion
142 can include information regarding, for example, an orientation
of the surface 133 of the anatomic structure 132. Additionally, or
alternatively, each anchor portion 142 can include information
regarding, for example, a degree of confidence in the location of
the anchor portions 142 and/or the associated information.
[0082] Identification of each anchor portion 142 can be based on
input received from a physician (e.g., as a tag), input received
from the tip section 124 in the anatomic structure 132, or a
combination thereof. More generally, it should be appreciated that
the identification of each anchor portion 142 can be based on
observations made or prior knowledge regarding the anatomic
structure 132 and can be independent of parameters used to form the
three-dimensional surface representation 136'.
[0083] Each anchor portion 142 can be represented on the graphical
user interface 110 as visual indicia. Such visual indicia can be
useful, for example, as a visualization tool for the physician to
assess how the three-dimensional surface representation 136' will
be modified as it is constrained to pass near a position relative
to the anchor portion 142. For example, based on observation of the
visual indicia representing the anchor portion 142 on the graphical
user interface 110, the physician can reposition the anchor portion
142.
[0084] The one or more anchor portions 142 can represent a position
of an anatomic feature of the anatomic structure 132. For example,
the one or more anchor portions 142 can correspond to locations at
which contact between the tip section 124 and the surface 133 of
the anatomic structure 132 is detected such that the one or more
anchor portions 142 represent a location known, optionally with
some confidence, to lie on the surface 133 of the anatomic
structure 132. In some instances, the one or more anchor portions
142 can include information regarding, for example, a direction of
contact corresponding to an orientation of the surface 133 of the
anatomic structure 132. Contact detection forming the basis of the
one or more anchor portions 142 can be based on any of various
different forms and combinations of contact detection described
herein or otherwise known in the art. For example, in cardiac
applications, contact detection can be based on an intracardiac
electrogram indicative of contact between the sensor 125 of the tip
section 124 and the surface 133. As another, non-exclusive example,
contact detection can also, or instead, be based on a force signal
(e.g., including magnitude, direction, or both) in implementations
in which the sensor 125 is a force sensor. As yet another,
non-exclusive example, contact detection can also, or instead, be
based on detecting deformation (e.g., using the sensor 125) of at
least a portion of the tip section 124 as the tip section 124
contacts the surface 133. As still another, non-exclusive example,
contact detection can also, or instead, be based on detecting a
change in impedance (e.g. using the sensor 125).
[0085] Additionally, or alternatively, the one or more anchor
portions 142 can be based on input from a physician. For example,
the input from the physician can be based on the unconstrained
three-dimensional surface representation 136' and the physician's
knowledge of anatomy. That is, the global shape of the
unconstrained three-dimensional surface representation 136' may
represent the overall shape of surface 133 of the anatomic
structure 132, albeit with local inaccuracies with respect to some
anatomic features. In such instances, the physician can provide an
indication of one or more anchor portions 142 on the
three-dimensional data structure 134 and/or on the unconstrained
three-dimensional surface representation 136' based on the
physician's knowledge of anatomy (e.g., knowledge of the position
of a carina in implementations directed to a heart cavity). As
another or alternative example, the physician can provide an
indication of one or more anchor portions 142 on the
three-dimensional data structure 134 and/or on the unconstrained
three-dimensional surface representation 136' based on observation
of the tip section 124 and/or the shaft 122. That is, in certain
instances, the physician can push the tip section 124 gently and
observe, optionally through fluoroscopy or other similar imaging
modality, whether the tip section 124 (FIG. 3) advances in response
to the push. If the tip section 124 (FIG. 3) does not advance in
response to the push, the physician can manually tag the point as
one of the one or more anchor portions 142.
[0086] The physician can identify the one or more anchor portions
142 on the three-dimensional data structure 134 by providing inputs
to the interface unit 108 (FIG. 1) (e.g., through a keyboard, a
mouse, or other input associated with the interface unit 108).
[0087] Referring now to FIG. 6C, the three-dimensional surface
representation 136 can be generated as a mesh (e.g., a continuous
polygonal mesh) of a surface extracted from the three-dimensional
data structure 134 and constrained relative to the one or more
anchor portions 142. As used herein, constraining the
three-dimensional surface representation 136 relative to the one or
more anchor portions 142 can include any one or more of various
different methods that, as compared to the absence of a constraint,
reduces the distance between the three-dimensional surface
representation 136 and the one or more anchor portions 142. For
example, constraining the three-dimensional surface representation
136 relative to the one or more anchor portions 142 can include
constraining the three-dimensional surface representation 136 to
pass through the one or more anchor portions 142. Additionally, or
alternatively, constraining the three-dimensional surface
representation 136 relative to the one or more anchor portions 142
can include constraining the three-dimensional surface
representation 136 to be at or within a distance (e.g., a fixed
distance) relative to the one or more anchor portions 142. As a
further or alternative example, the three-dimensional surface
representation 136 can be constrained by a penalty (e.g., cost)
function that penalizes for distance from the one or more anchor
portions 142 but does not strictly restrict the three-dimensional
surface representation 136 to pass within a specified distance of
the one or more anchor portions 142.
[0088] Referring to FIGS. 6A-6C, in certain implementations,
constraining the three-dimensional surface representation 136
relative to the one or more anchor portions can include setting a
fixed value of one or more nodes associated with the one or more
anchor portions 142 in the three-dimensional data structure 134,
determining a scalar function on at least a portion of the
three-dimensional data structure 134, and applying an algorithm to
extract an isosurface based in part on the scalar function. An
indicator function is a well-known example of such a scalar
function. An embedding function is another well-known example of
such a scalar function. The isosurface extracted based at least in
part on the scalar function can include any of various different
isosurfaces known in the art and, thus, among various examples, can
include an implicit surface.
[0089] As an example, constraining the three-dimensional surface
representation 136 can include a clamped signed distance function
based only on space carving information, as is well known in the
art. Specifically, a first fixed value can be assigned to nodes, in
the three-dimensional data structure 134, corresponding to
locations within the anatomic structure 132 (FIG. 3) visited by the
tip section 124 of the medical device 104 (FIG. 2). Because the tip
section 124 of the medical device 104 (FIG. 2) can only move
through blood, the nodes with the first fixed value in the
three-dimensional data structure 134 imply the presence of blood at
those positions. However, because the tip section 124 of the
medical device 104 (FIG. 2) does not generally move through every
location within the anatomic structure 132 (FIG. 3), the nodes that
have not been set to the first fixed value can correspond to one of
two physical states. That is, the nodes that have not been set to
the first fixed value can correspond to i) locations in the
anatomic structure 132 (FIG. 3) that have not been visited by the
tip section of the medical device 104 (FIG. 2) or ii) locations
that are outside of the volume of the anatomic structure 132 in
which the tip section 124 of the medical device 104 (FIG. 2) is
moving. In general, inaccuracies in the three-dimensional surface
representation 136 (such as the inaccuracies shown in FIGS. 5A and
5B) can arise from mischaracterization of these two categories of
nodes that have not been set to the first fixed value.
[0090] Continuing with this example, because the one or more anchor
portions 142 correspond to one or more locations on the surface 133
of the anatomic structure 132 (FIG. 3), the one or more anchor
portions 142 can provide a constraint that is useful for more
accurately characterizing nodes that that have not been set to the
first fixed value. In some implementations, the one or more anchor
portions 142 can be set to a second fixed value, different from the
first fixed value. It should be appreciated that the second fixed
value can be one of two values of a signed clamped distance
function, and the anchor portions 142 can correspond to surfaces
acquired from a range scan. In this example, therefore, nodes
corresponding to the first fixed value can correspond to the known
locations of blood while nodes corresponding to the second fixed
value can correspond to the known locations of the surface 133
(FIG. 3) and, thus, the blood-tissue boundary. The values of the
remaining nodes in the three-dimensional data structure 134 (i.e.,
the nodes that have been assigned neither the first fixed value nor
the second fixed value) are variable.
[0091] As is known in the art, a volumetric smoothing algorithm
(e.g., a three-dimensional smoothing kernel) can be applied to the
three-dimensional data structure 134, and the values of these
variable nodes can take on values that are a function of
neighboring nodes. For example, the values of the variable nodes
can take on values that are a function of neighboring nodes
according to a thermal diffusion model. It should be appreciated
that, because the one or more anchor portions 142 have a fixed
value in this example, the one or more anchor portions 142 can
modify the values of neighboring variable nodes as the
three-dimensional data structure 134 undergoes volumetric
smoothing. For example, a spatial convolution can be applied one or
more times to calculate new values for only the variable nodes.
[0092] The three-dimensional surface representation 136 can be
based on the three-dimensional data structure 134 having
fixed-value nodes as described above. For example, the
three-dimensional surface representation 136 can correspond to an
isosurface (e.g., a level set, an implicit surface, etc.) extracted
from the three-dimensional data structure 134 having fixed-value
nodes. In certain implementations, a "marching cubes" algorithm can
be applied to the volumetrically smoothed three-dimensional data
structure 134 having fixed-value nodes to extract an isosurface
corresponding to a fixed value (e.g., a value between the first
fixed value associated with known locations of the tip section 124
of the medical device 104 (FIG. 2) and the second fixed value
associated with the one or more anchor portions 142). In this way,
the one or more anchor portions 142 can have the effect of
constraining, or otherwise limiting, the position of the resulting
three-dimensional surface representation 136 extracted from the
three-dimensional data structure 134. Additionally, or
alternatively, a "flying edges" algorithm can be applied to the
volumetrically smoothed three-dimensional data structure 134 to
extract an isosurface.
[0093] Further, or instead, the three-dimensional surface
representation 136 can be based on any of various different
algorithms well known in the art for extracting a mesh of a surface
from the three-dimensional data structure 134. Thus, for example,
the three-dimensional surface representation 136 can be a polygonal
mesh extracted from the three-dimensional data structure 134 based
on a "marching cubes" algorithm and constrained relative to the one
or more anchor points 142 according to any of the various different
methods described herein. As used herein, a "marching cubes"
algorithm can include any one or more algorithms in which a
polygonal mesh of an isosurface is extracted from the
three-dimensional data structure 134 based on analysis of node
values in the three-dimensional data structure 134. More generally,
the three-dimensional surface representation 136 can be extracted
from the three-dimensional data structure 134 according to any one
or more computational algorithms known in the art for
volumetrically smoothing three-dimensional representations of
objects including a "ball-pivoting" algorithm, a "power crust"
algorithm, and other similar algorithms.
[0094] As an example, an adaptive ball-pivoting algorithm can
constrain the three-dimensional surface representation 136 relative
to the anchor portions 142. That is, away from the anchor portions
142, the ball forming the basis of the ball-pivoting algorithm can
be a fixed global size that yields volumetric smoothing where
specific information about anatomical features is not available.
For example, the fixed global ball can have a diameter between
about 10 mm and 30 mm (e.g. about 15 mm). Close to the anchor
portions 142, the size of the ball can be reduced to facilitate
passing the surface representation 136 closer to the anchor
portions 142. For example, as compared to the fixed global size of
the ball away from the anchor portions 142, the size of the ball
can be reduced closer to the anchor portions 142. With such a
reduced ball size, as compared to the fixed global size, the
three-dimensional surface representation 136 can pass closer to the
anchor portions 142. As a more specific example, the size of the
ball at a surface location closest to a respective one of the
anchor portions 142 can be chosen such that the three-dimensional
surface representation 136 lies within a predetermined minimum
distance to the respective anchor portion 142. In certain
implementations, the size of the ball can vary between the reduced
ball size and the global ball size as a function (e.g., a linear
function) of distance from the ball to the one or more anchor
portions 142 until the ball size reaches the global ball size,
beyond which distance the global ball size can remain at the fixed
global ball size.
[0095] As shown in FIG. 6C, the three-dimensional surface
representation 136 can be volumetrically smoothed and, optionally,
surface smoothed. For example, volumetric smoothing of the
three-dimensional surface representation 136 can be accomplished
using any one or more of various different volumetric smoothing
techniques that are well known in the art and described herein.
Surface smoothing can additionally, or alternatively, be
accomplished using any one or more of various different surface
smoothing techniques well known in the art. An example of such a
surface smoothing technique is Laplacian smoothing and variations
thereof. In certain instances, through surface smoothing,
three-dimensional surface representation 136 may no longer satisfy
the constraints previously applied as part of the volumetric
smoothing process. For example, as shown in FIG. 6C, the
surface-smoothed three-dimensional surface representation 136 may
contain fewer than all of the locations visited by the medical
device. Further, or instead, the distance between the
three-dimensional surface representation 136 and the anchor
portions 142 may change as the three-dimensional surface
representation 136 is subjected to surface smoothing.
[0096] Comparing FIG. 6B to FIG. 6C, it should be appreciated that
the three-dimensional surface representation 136 differs from the
unconstrained three-dimensional surface representation 136' near
the one or more anchor portions 142. In particular, because the
three-dimensional surface representation 136 is constrained
relative to the one or more anchor portions 142, the
three-dimensional surface representation 136 depicts anatomic
features that are not readily apparent in the unconstrained
three-dimensional surface representation 136'. Accordingly, it
should be further appreciated that the one or more anchor portions
142 can facilitate efficiently generating an accurate
representation of anatomic features of the anatomic structure 132
(FIG. 3).
[0097] Referring now to FIG. 6D, the display of the
three-dimensional data structure 134 of FIG. 6C can be hidden
(e.g., made translucent) such that the three-dimensional surface
representation 136 can be displayed by itself. The display of the
three-dimensional surface representation 136 by itself and,
optionally, in smoothed form can be useful, for example, for
facilitating perception by the physician.
[0098] The steps shown in FIGS. 6A-6D have been shown and described
as occurring in sequence for the sake of clarity of explanation. It
should be appreciated, however, that in addition to, or as an
alternative, any one or more of the steps shown in FIGS. 6A-6D can
be combined, performed in parallel, and/or varied in order.
[0099] The computer executable instructions stored on the storage
medium 111 (FIG. 1) can cause the processing unit 109 (FIG. 1) to
generate the three-dimensional surface representation 136 according
to one or more of the following exemplary methods. Unless otherwise
indicated or made clear from the context, each of the following
exemplary methods can be implemented using the system 100 (FIG. 1)
and/or one or more components thereof.
[0100] FIG. 7 is a flowchart of an exemplary method 160 of
representing a surface of an anatomic structure. The exemplary
method 160 can include receiving 162 a plurality of location
signals of a medical device, forming 164 a three-dimensional data
structure representing volumes, within the anatomic structure,
occupied by the medical device at the locations corresponding to
the plurality of location signals, receiving 166 one or more anchor
portions representing locations relative to the anatomic structure,
and generating 167 a three-dimensional surface representation of
the anatomic structure. The generated 167 three-dimensional surface
representation can be constrained relative to the one or more
anchor portions and to contain at least a portion of the
three-dimensional data structure. That is, in general, the one or
more anchor portions can modify the behavior of an algorithm in a
way that constrains the resulting three-dimensional surface
representation relative to the anchor portions.
[0101] In general, receiving 162 the plurality of location signals
of the medical device can include receiving one or more signals
indicative of the location of the medical device according to any
one or more of the methods described herein. The received 162
plurality of location signals can be, for example, a plurality of
signals received from a single sensor over a period of time. For
example, the received 162 plurality of location signals can be one
or more signals from a magnetic position sensor (such as the
magnetic position sensor 130 described above with respect to FIG.
2). Additionally, or alternatively, the received 162 plurality of
location signals can be a plurality of signals received from
multiple, different types of sensors that individually, or in
combination, provide information regarding the location of the
medical device in the anatomic structure. As an example, greater
details of which are described below, receiving 162 the plurality
of location signals of the medical device can include receiving one
or more signals from a magnetic position sensor and from a sensor
providing a signal indicative of a blood-tissue boundary of the
anatomic structure.
[0102] As used herein, the received 162 plurality of location
signals of the medical device generally correspond to locations
visited by a tip section of the medical device (e.g., the tip
section 124 of the medical device 104 of FIG. 2) in the anatomic
structure. More generally, however, it should be understood that
the plurality of location signals of the medical device can
correspond to locations visited by any portion of the medical
device that can be sensed or otherwise determined in the anatomic
structure.
[0103] Forming 164 the three-dimensional data structure
representing locations, within the anatomic structure, visited by
the medical device can include forming a three-dimensional grid,
with locations in the three-dimensional grid reflecting locations
visited by the medical device in the anatomic structure. In such
implementations, a boundary of the anatomic structure can be
approximated through analysis of neighbor locations and/or node
values of the three-dimensional grid such as, for example, through
application of one or more of a "marching cubes" algorithm, a
"ball-pivoting" algorithm, and a "power crust" algorithm, with the
algorithm or algorithms extracting a surface from the
three-dimensional grid. In some implementations, the one or more
anchor portions (e.g., the anchor portions 142 in FIGS. 5A-5C) can
be represented by respective constrained values (or combinations
thereof) on the three-dimensional grid or, more generally, on any
type of three-dimensional data.
[0104] In general, receiving 166 the one or more anchor portions
representing locations relative to the anatomic structure can
include receiving input from one or more sources. For example,
receiving 166 the one or more anchor portions can be based on input
received from a physician, input received from one or more sensors
on the medical device, or a combination thereof. In instances in
which receiving 166 the one or more anchor portions is based on a
combination of input from the physician and from one or more
sensors on the medical device, it can be advantageous to have a
hierarchy of input such that, for example, the input from the
physician can override the input from the one or more sensors on
the medical device.
[0105] Receiving 166 the one or more anchor portions representing
locations relative to the anatomic structure can include receiving,
from one or more sensors disposed on the medical device, a signal
indicative of contact between the medical device and tissue of the
anatomic structure. Sensed contact (e.g., one or more of location,
direction, force, consistency, and/or duration of contact) between
the medical device and the surface of the anatomic structure can be
indicative of a blood-tissue boundary of the anatomic structure of
the patient. Accordingly, one or more anchor portions can be
identified at the location of the sensed contact to ensure that the
three-dimensional surface representation is constrained relative to
the sensed contact, which is known to represent the blood-tissue
boundary.
[0106] It should be appreciated that such a signal indicative of
contact between the medical device and tissue of the anatomic
chamber can include any one or more of the signals indicative of
contact described herein. Thus, for example, the signal indicative
of contact between the medical device and tissue of the anatomic
chamber can include an impedance signal (e.g., a change in
impedance) from one or more impedance sensors (e.g., the sensor 125
in FIG. 2) disposed on the medical device. Additional or
alternative examples of signals indicative of contact between the
medical device and the surface of the anatomic structure of the
patient can include one or more of: a change in an electrical
signal (e.g., electrogram or impedance) in one or more electrodes
of the medical device; a force detected by a force sensor of the
medical device; an ultrasound signal of an ultrasound sensor on the
medical device; and a deformation of at least a portion of the
medical device. As a more specific example, a signal indicative of
contact between the medical device and the surface of the anatomic
structure of the patient can include an amplitude derived from an
electrogram detected by one or more electrodes of the medical
device.
[0107] Receiving 166 the one or more anchor portions can include
identification of a subset of the plurality of received location
signals. Identification of the subset of the plurality of received
location signals can, for example, include an input command from
the physician identifying one or more portions of the
three-dimensional data structure as corresponding one or more
anchor portions. The input command can be received from any of
various, different input devices such as a keyboard, a mouse, a
touchscreen, etc. and, additionally, or alternatively, can include
voice commands. Thus, in implementations in which the data
structure includes a three-dimensional grid, the physician can
provide input through one or more input devices to identify the
subset as one or more voxels of the three-dimensional grid, as
displayed on a graphical user interface.
[0108] In certain implementations, receiving 166 the one or more
anchor portions can include receiving a respective confidence level
associated with the one or more anchor portions. For example, a
confidence level can increase substantially monotonically with a
measured indication of contact (e.g. electrogram amplitude,
impedance, force, deformation, and/or proximity). In such
implementations, constraining the three-dimensional surface
representation relative to the one or more anchor portions can be
based on the respective confidence level associated with each of
the one or more anchor portions. For example, the confidence levels
can form a basis for certain of the one or more anchor portions
acting as stronger or weaker anchor portions relative to other
anchor portions. That is, an anchor portion corresponding to a
higher confidence level can act as a stronger anchor as compared to
an anchor portion corresponding to a weaker confidence level.
Additionally, or alternatively, an anchor portion identified with
contact in a known direction can constrain the normal direction of
the resulting surface using any of various different techniques
known in the art.
[0109] In general, generating 167 the three-dimensional surface
representation of the anatomic structure can include any one or
more of the methods described herein for forming a
three-dimensional surface. Thus, for example, generating 167 the
three-dimensional surface representation can include extracting a
surface from the three-dimensional data structure according to an
algorithm, such as one or more of a "marching cubes" algorithm, a
"ball-pivoting" algorithm, and a "power crust" algorithm, in which
the three-dimensional surface representation is constrained
relative to the one or more anchor portions according to any one or
more of the various different methods of constraint described
herein.
[0110] Additionally, or alternatively, the three-dimensional
surface representation can include a mesh (e.g., a continuous
mesh). The mesh can be formed of, for example, a plurality of
polygons (e.g., triangles) combined together to represent contours
of the surface of the anatomic structure.
[0111] In some implementations, the generated 167 three-dimensional
surface representation can be smoothed according to any of various
different smoothing techniques known in the art to provide a more
realistic representation of the surface of the anatomic
structure.
[0112] The exemplary method 160 can optionally include representing
168, on a graphical user interface, any of various different
combinations of the three-dimensional surface representation, the
anchor portions, and the three-dimensional data structure. The
graphical user interface can be, for example, a two-dimensional
graphical user interface such as the graphical user interface 110
(FIG. 1). Accordingly, the exemplary method 160 can include
representing 168, on the graphical user interface, a
two-dimensional projection of the three-dimensional surface
representation. In addition, or in the alternative, the exemplary
method 160 can include representing 168, on the graphical user
interface, a two-dimensional projection of the three-dimensional
data structure.
[0113] In certain implementations, the exemplary method 160 can
further include representing 168 the one or more anchor portions on
the graphical user interface. For example, the one or more anchor
portions can be represented 168 on the graphical user interface on
a projection of the three-dimensional data structure, on a
projection of the three-dimensional surface representation, or
both. Additionally, or alternatively, the one or more anchor
portions can be represented 168 on the graphical user interface
separately from the three-dimensional data structure and/or the
three-dimensional surface. It should be appreciated that
representing 168 the one or more anchor portions on the graphical
user interface can, for example, facilitate modification of the one
or more anchor portions in certain instances. Additionally, or
alternatively, the one or more anchor portions can be represented
168, on the graphical user interface, as annotations on the
three-dimensional surface representation of the anatomic structure.
The annotations can include, for example, tags of corresponding
anatomic features, tags corresponding to locations for application
of treatment (e.g., ablation), or combinations thereof. By way of
example, the annotations can constrain the three-dimensional
surface representation to remain unchanged as other anchor portions
are added. As a further or alternative example, the
three-dimensional surface representation can be constrained to pass
through a portion of the three-dimensional data structure nearest
to the annotation.
[0114] In certain implementations, the exemplary method 160 can
optionally include determining 169 whether the one or more anchor
portions have been modified. If the one or more anchor portions are
determined 169 to be modified, the generating step 167 can be
repeated. Thus, in general, the exemplary method 160 can be
iterative. That is, in response to the generated 167
three-dimensional surface representation, the physician can
continue to make modifications as necessary. These modifications
can be based on one or more inputs received from any one or more of
various input devices known in the art and described herein.
Accordingly, modifying the one or more anchor portions can be based
on one or more inputs from a keyboard, a mouse, a touchscreen, the
medical device, or combinations thereof.
[0115] Modifying the one or more anchor portions can include
removing at least one of the one or more anchor portions. Such
removal can be useful, in certain instances, for adjusting the
three-dimensional surface representation (e.g., after the
three-dimensional surface representation has been generated 167) to
achieve a shape that is more accurate. Additionally, or
alternatively, removal of at least one of the one or more anchor
portions can correct an incorrectly identified anchor portion. It
should be appreciated, therefore, that removal of at least one of
the one or more anchor portions can serve as an "undo" function
such that correction of an incorrectly identified anchor portion
does not require the physician to engage, for example, in a complex
editing process. More generally, modifying the identified one or
more anchor portions and repeating the generating step 167 as part
of the iterative process described herein can facilitate efficient
and accurate generation of the three-dimensional surface
representation of the anatomic structure, as compared to tools that
allow a user to selectively delete subvolumes. That is, selecting a
subvolume on a two-dimensional graphical user interface commonly
requires multiple selection steps from different views, which can
be time consuming and subject to inaccuracies and can often require
complex user interaction.
[0116] FIG. 8 is a flowchart of an exemplary method 170 of
representing a surface of a heart cavity of a patient. The
exemplary method 170 can include forming 172 a three-dimensional
data structure based on received locations of a tip section of a
cardiac catheter in a heart cavity of a patient, receiving 174
identification of one or more anchor portions representing
locations within the heart cavity, and generating 176 a
three-dimensional surface representation of the heart cavity of the
patient. The three-dimensional surface representation can be
generated using information from the three-dimensional data
structure and can be constrained relative to the one or more anchor
portions. The tip section of the catheter can be, for example, the
tip section 124 described with respect to FIGS. 2 and 3.
Additionally, or alternatively, it should be appreciated that a
heart cavity is an example of the anatomic structure 132.
Accordingly, the tip section can interact with the heart cavity in
any manner and form described herein with respect to the
interaction of the tip section 124 and the anatomic structure
132.
[0117] Forming 172 the three-dimensional data structure can include
any one or more of the various different methods of forming a
three-dimensional data structure disclosed herein. For example,
forming 172 the three-dimensional data structure can be analogous
to forming 164 the three-dimensional data structure as described
with respect to FIG. 7. Accordingly, forming 172 the
three-dimensional data structure can be based on locations visited
by the catheter in the heart cavity. Thus, in implementations in
which the three-dimensional data structure includes a
three-dimensional grid, voxels corresponding to visited locations
of the catheter can be set to a different state than voxels
corresponding to locations that have not been visited by the
catheter.
[0118] In general, receiving 174 the one or more anchor portions on
the three-dimensional data structure can be analogous to receiving
166 the one or more anchor portions on the three-dimensional data
structure, as described with respect to FIG. 7. Thus, for example,
receiving 174 the one or more anchor portions on the
three-dimensional data structure can include receiving an input
command from a user interface (e.g., an input device such as a
keyboard, a mouse, a touchscreen, and the like) corresponding to a
location of an anatomic feature and/or receiving a signal
indicative of contact between the catheter and tissue in the heart
cavity. In the case of the heart cavity, the one or more anchor
portions can correspond, for example, to the location of one or
more carina associated with the heart cavity. As a more specific
example, the one or more anchor portions can correspond to a carina
between the left atrial appendage (LAA) and the left superior
pulmonary vein (LSPV).
[0119] In the alternative, or in addition, receiving 174 the one or
more anchor portions can include receiving one or more signals
corresponding to one or more respective locations of the cardiac
catheter in the heart cavity. For example, the one or more signals
corresponding to one or more respective locations of the cardiac
catheter in the heart cavity can correspond to a blood-tissue
boundary of the heart cavity. Such signals can include, for
example, to one or more of: a change in an electric signal (e.g.,
electrogram or impedance) detected by one or more electrodes of the
catheter, a force detected by a force sensor of the catheter, an
ultrasound signal of an ultrasound sensor of the catheter, and a
deformation of at least a portion of the catheter. For example,
such signals can correspond to an amplitude derived from an
electrogram detected by one or more electrodes of the medical
device.
[0120] Generating 176 the three-dimensional surface representation
of the heart cavity of the patient can be, in general, analogous to
generating 167 the three-dimensional surface representation of the
anatomic structure as described with respect to FIG. 7.
Accordingly, it should be understood that generating 176 the
three-dimensional surface representation of the heart cavity can be
based, for example, on one or more of a "marching cubes" algorithm,
a "ball-pivoting" algorithm, and a "power crust algorithm," with
the algorithm or algorithms constrained relative to the one or more
anchor portions. Further, or instead, generating 176 the
three-dimensional surface representation of the heart cavity of the
patient can include an undo function such that one or more of the
anchor portions can be removed or repositioned, and the
three-dimensional surface representation of the heart cavity can be
regenerated based on the updated position of the one or more anchor
portions.
[0121] In certain implementations, the three-dimensional surface
representation of the heart cavity can be surface smoothed. It
should be appreciated that such surface smoothing can produce
changes to the three-dimensional surface representation and, in
certain instances, can cause the three-dimensional surface
representation to no longer fully contain the visited locations.
Additionally, or alternatively, surface smoothing can produce
changes to the three-dimensional surface representation that can
cause the three-dimensional surface representation to no longer
pass directly through the anchor portions. Surface-smoothing the
three-dimensional surface representation can result in any one or
more of the various different advantages described herein. For
example, surface smoothing the three-dimensional surface
representation can facilitate visualization of the position of the
catheter relative to the three-dimensional surface representation,
which can be useful for positioning the catheter during an ablation
treatment applied to a surface of the heart cavity.
[0122] In some implementations, the exemplary method 170 can
further include representing 177, on a graphical user interface, at
least one of a two-dimensional projection of the three-dimensional
data structure, the one or more anchor portions, and a
two-dimensional projection of the three-dimensional surface
representation. Representing 177 the two-dimensional projection of
the three-dimensional surface representation and generating 176 the
three-dimensional surface representation can be part of an
iterative process, such as an iterative process analogous to the
iterative process described with respect to the exemplary method
160.
[0123] The graphical user interface can be, for example, the
graphical user interface 110 described with respect to FIG. 1. In
certain implementations, the one or more anchor portions can be
represented 177, on the graphical user interface, as annotations or
other similar visual indicia on the three-dimensional surface
representation of the heart cavity, on the three-dimensional data
structure, or both. Additionally, or alternatively, the one or more
anchor portions can be represented 177 on the graphical user
interface independently of the three-dimensional surface
representation, the three-dimensional data structure, or both. The
annotations can, for example, be tags of certain anatomic features
and/or tags related to the position of a treatment (such as a
lesion created through tissue ablation).
[0124] While certain implementations have been described, other
implementations are additionally or alternatively possible.
[0125] For example, while graphical user interfaces have been
described as including a two-dimensional display, any one or more
of the graphical user interfaces described herein can additionally,
or alternatively, include a three-dimensional display. Examples of
such a three-dimensional display include an augmented reality
environment, a virtual reality environment, and combinations
thereof.
[0126] The above systems, devices, methods, processes, and the like
may be realized in hardware, software, or any combination of these
suitable for a particular application. The hardware may include a
general-purpose computer and/or dedicated computing device. This
includes realization in one or more microprocessors,
microcontrollers, embedded microcontrollers, programmable digital
signal processors or other programmable devices or processing
circuitry, along with internal and/or external memory. This may
also, or instead, include one or more application specific
integrated circuits, programmable gate arrays, programmable array
logic components, or any other device or devices that may be
configured to process electronic signals.
[0127] It will further be appreciated that a realization of the
processes or devices described above may include
computer-executable code created using a structured programming
language such as C, an object oriented programming language such as
C++, or any other high-level or low level programming language
(including assembly languages, hardware description languages, and
database programming languages and technologies) that may be
stored, compiled or interpreted to run on one of the above devices,
as well as heterogeneous combinations of processors, processor
architectures, or combinations of different hardware and software.
In another aspect, the methods may be embodied in systems that
perform the steps thereof, and may be distributed across devices in
a number of ways. At the same time, processing may be distributed
across devices such as the various systems described above, or all
of the functionality may be integrated into a dedicated, standalone
device or other hardware. In another aspect, means for performing
the steps associated with the processes described above may include
any of the hardware and/or software described above. All such
permutations and combinations are intended to fall within the scope
of the present disclosure.
[0128] Embodiments disclosed herein may include computer program
products comprising computer-executable code or computer-usable
code that, when executing on one or more computing devices,
performs any and/or all of the steps thereof. The code may be
stored in a non-transitory fashion in a computer memory, which may
be a memory from which the program executes (such as random access
memory associated with a processor), or a storage device such as a
disk drive, flash memory or any other optical, electromagnetic,
magnetic, infrared or other device or combination of devices.
[0129] In another aspect, any of the systems and methods described
above may be embodied in any suitable transmission or propagation
medium carrying computer-executable code and/or any inputs or
outputs from same.
[0130] The method steps of the implementations described herein are
intended to include any suitable method of causing such method
steps to be performed, consistent with the patentability of the
following claims, unless a different meaning is expressly provided
or otherwise clear from the context. So for example performing the
step of X includes any suitable method for causing another party
such as a remote user, a remote processing resource (e.g., a server
or cloud computer) or a machine to perform the step of X.
Similarly, performing steps X, Y and Z may include any method of
directing or controlling any combination of such other individuals
or resources to perform steps X, Y and Z to obtain the benefit of
such steps. Thus method steps of the implementations described
herein are intended to include any suitable method of causing one
or more other parties or entities to perform the steps, consistent
with the patentability of the following claims, unless a different
meaning is expressly provided or otherwise clear from the context.
Such parties or entities need not be under the direction or control
of any other party or entity, and need not be located within a
particular jurisdiction.
[0131] It will be appreciated that the methods and systems
described above are set forth by way of example and not of
limitation. Numerous variations, additions, omissions, and other
modifications will be apparent to one of ordinary skill in the art.
In addition, the order or presentation of method steps in the
description and drawings above is not intended to require this
order of performing the recited steps unless a particular order is
expressly required or otherwise clear from the context. Thus, while
particular embodiments have been shown and described, it will be
apparent to those skilled in the art that various changes and
modifications in form and details may be made therein without
departing from the spirit and scope of this disclosure and are
intended to form a part of the invention as defined by the
following claims.
* * * * *
References