U.S. patent application number 13/958954 was filed with the patent office on 2014-05-08 for preoperative surgical simulation.
This patent application is currently assigned to SIMBIONIX LTD.. The applicant listed for this patent is SIMBIONIX LTD.. Invention is credited to Ran BRONSTEIN, Niv FISHER, Ofek SHILON.
Application Number | 20140129200 13/958954 |
Document ID | / |
Family ID | 39636461 |
Filed Date | 2014-05-08 |
United States Patent
Application |
20140129200 |
Kind Code |
A1 |
BRONSTEIN; Ran ; et
al. |
May 8, 2014 |
PREOPERATIVE SURGICAL SIMULATION
Abstract
An apparatus for simulating an image-guided procedure. The
system comprises an input for receiving a three-dimensional (3D)
medical image depicting an organ of a patient, a model generation
unit for generating a 3D anatomical model of the organ according to
the 3D medical image, and a simulating unit for simulating a
planned image-guided procedure on the patient, according to the 3D
anatomical model.
Inventors: |
BRONSTEIN; Ran; (Modiin,
IL) ; FISHER; Niv; (Ramat Gan, IL) ; SHILON;
Ofek; (Kfar Sava, IL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SIMBIONIX LTD. |
Lod |
|
IL |
|
|
Assignee: |
SIMBIONIX LTD.
Lod
IL
|
Family ID: |
39636461 |
Appl. No.: |
13/958954 |
Filed: |
August 5, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12224314 |
Aug 22, 2008 |
8500451 |
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PCT/IL2008/000056 |
Jan 13, 2008 |
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13958954 |
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60880415 |
Jan 16, 2007 |
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Current U.S.
Class: |
703/11 |
Current CPC
Class: |
G16H 50/50 20180101;
G16H 30/20 20180101; G06T 19/00 20130101; A61B 34/10 20160201; G16H
30/40 20180101; G06T 2210/41 20130101; G06T 17/00 20130101 |
Class at
Publication: |
703/11 |
International
Class: |
A61B 19/00 20060101
A61B019/00 |
Claims
1. An apparatus for simulating an image-guided procedure,
comprising: an input unit to receive a three-dimensional (3D)
medical image specific to an actual patient undergoing a specific
medical procedure obtained by a medical imaging system depicting an
anatomical region of the patient undergoing the specific medical
procedure wherein the medical image is obtained after administering
an intravenous contrast enhancement (ICE) component to the patient
in order to improve precision of an automatic 3D segmentation
process related to a soft tissue; a 3D segmentation unit to perform
the automatic segmentation process on the 3D medical image specific
to the patient and for producing a segmented 3D medical image,
wherein the automatic segmentation process comprises classification
of data voxels according to respective anatomical parts of said
anatomical region and registration of said anatomical region; a
model generation unit to generate a 3D anatomical model of said
anatomical region, according to said segmented 3D medical image;
and a simulating unit to simulate an image-guided procedure planned
for said patient according to said 3D anatomical model.
2. The apparatus of claim 1, wherein the 3D medical image is
represented in a 3D data array and the 3D segmentation unit
receives as input the 3D data array.
3. The apparatus of claim 1, where said 3D medical image is
represented in digital imaging and communication in medicine
(DICOM) format and said 3D anatomical model is presented by sets of
data comprising a 3D spline description and polygonal meshes
representation.
4. The apparatus of claim 1, wherein said 3D anatomical model is a
model of a tract and said tract is a member of the following group:
a vascular tract, a urinary tract, a gastrointestinal tract, and a
fistula tract.
5. The apparatus of claim 1, wherein said 3D medical image is a
member of the following group: computerized tomography (CT) scan
images, magnetic resonance imager (MRI) scan images, ultrasound
scan images, and positron emission tomography (PET)-CT scan
images.
6. The apparatus of claim 1, wherein said planned image-guided
procedure is an angioplasty procedure.
7. The apparatus of claim 1, further comprising a user interface
operatively connected to said model generation unit, said user
interface is to accept input data that identifies a location in the
3D medical image;
8. The apparatus of claim 1, wherein said simulated planned
image-guided procedure is used as a study case during a learning
process.
9. The apparatus of claim 1, wherein said simulated planned
image-guided procedure is used to demonstrate a respective
image-guided procedure to said patient.
10. The apparatus of claim 1, wherein said simulated planned
image-guided procedure is used to document preparation to an
operation.
11. The apparatus of claim 1, wherein said input unit is configured
for receiving a four dimensional (4D) medical image, which is a set
of consecutive 3D medical images that depicts said anatomical
region during a time period, said model generation unit is
configured for generating a 4D anatomical model according to said
4D medical image, said simulating unit is configured for simulating
an image-guided procedure planned for said patient according to
said 4D anatomical model.
12. The apparatus of claim 1, wherein said anatomical region is a
member of a group comprising: an organ, a human body system, an
area of an organ, a number of areas of an organ, a section of an
organ, and a section of a human body system.
13. A method for performing a simulated image-guided procedure,
said method comprising: obtaining, by a medical imaging system, a
three-dimensional (3D) medical image specific to an actual patient
undergoing a specific medical procedure, depicting an anatomical
region of the patient undergoing the specific medical procedure,
wherein the medical image is obtained after administering an
intravenous contrast enhancement (ICE) component to the patient in
order to improve precision of an automatic 3D segmentation process
related to a soft tissue; performing, by a computer processor, the
automatic 3D segmentation process on the 3D medical image specific
to the patient to produce a segmented 3D medical image, wherein the
automatic segmentation process comprises classifying data voxels
according to respective anatomical parts of said anatomical region
and registering said anatomical region; producing, by the computer
processor, a 3D anatomical model of said anatomical region
according to said segmented 3D medical image; and simulating an
image-guided procedure planned for said patient according to said
3D anatomical model.
14. The method of claim 13, wherein the 3D medical image is
represented in a 3D data array and the 3D segmentation unit
receives as input the 3D data array.
15. The method of claim 13, wherein said planned image-guided
procedure is an angioplasty procedure.
16. The method of claim 13 comprising: receiving input data that
identifies a location in the 3D medical image in relation to the
automatic segmentation process.
17. The method of claim 13, wherein said simulating comprises
displaying said 3D anatomical model as a display on an image
display device coupled to the computer processor.
18. The method of claim 17, further comprising a step of allowing a
system user to mark labels for said planned image-guided procedure
according to said display.
19. The method of claim 13, wherein said planned image-guided
procedure is an angioplasty procedure.
20. The method of claim 13, wherein said step of simulating is
performed as a pre-operative surgical simulation.
21-25. (canceled)
Description
FIELD AND BACKGROUND OF THE INVENTION
[0001] The present invention relates to an apparatus and a method
for performing a simulated image-guided medical procedure and, more
particularly, but not exclusively to performing a simulated
image-guided procedure according to a three-dimensional (3D) model
of an organ that is based on a 3D medical image.
[0002] Medical imaging is generally recognized as important for
diagnosis and patient care with the goal of improving treatment
outcomes. In recent years, medical imaging has experienced an
explosive growth due to advances in imaging modalities such as
x-rays, computed tomography (CT), magnetic resonance imaging (MRI)
and ultrasound. These modalities provide noninvasive methods for
studying internal organs in vivo, but the amount of data is
relatively large and when presented as two dimensional (2D) images,
it generally requires an anatomist/radiology specialist for
interpretation. Unfortunately, the cost incurred in manual
interpretation of this data is prohibitive for routine data
analysis. The 2D slices can be combined to generate a 3-D
volumetric model.
[0003] Such medical imaging systems allow the performance of
minimally invasive therapeutic procedures. These procedures are
typically carried out in a CathLab, where a physician wishes to
assess the functions of internal organ such as the heart and
coronary artery or to perform procedures such as coronary
angioplasty.
[0004] Most radiology yields recorded images such as 2D X-ray films
or 3D medical images such as CT and MRI scans. Mild dosage
interactively controlled X-Ray, also known as fluoroscopy, allows a
physician to monitor actively an operation at progress.
Interventional radiology is the specialty in which the radiologist
and cardiologists utilizes real time radiological images to perform
therapeutic and diagnostic procedures. Interventional radiologists
currently rely on the real-time fluoroscopic 2D images, available
as analog video or digital information viewed on video
monitors.
[0005] However, these procedures involve delicate and coordinated
hand movements, spatially unrelated to the view on a video monitor
of the remotely controlled surgical instruments. Depth perception
is lacking on the flat video display and therefore it is not an
easy task to learn to control the tools through the spatially
arbitrary linkage. A mistake in this difficult environment can be
dangerous. Therefore, a high level of skill is required, and a
realistic training of these specialists is a complex task. In
addition, usually there is no direct engagement of the depth
perception of the radiologist, who must make assumptions about the
patient's anatomy to deliver therapy and assess the results.
[0006] Medical simulators that can be used to train such medical
specialists have significant potential in reducing healthcare costs
through improved training, better pre-treatment planning, and more
economic and rapid development of new medical devices. Hands-on
experience becomes possible in training, before direct patient
involvement that will carry a significant risk.
[0007] Image-guided procedures, such as vascular catheterization,
angioplasty, and stent placement, are specially suited for
simulation because they typically place the physician at-a-distance
from the operative site manipulating surgical instruments and
viewing the procedures on video monitors.
[0008] For example, U.S. Pat. No. 6,062,866 published on May 16,
2000 describes a medical model for teaching and demonstrating
invasive medical procedures such as angioplasty. The model is a
plastic, transparent three-dimensional, anatomically correct
representation of at least a portion of the vascular system and in
a preferred embodiment would include the aorta, coronary artery,
subclavian arteries, pulmonary artery and renal arteries each
defining a passageway or lumen. An access port is provided so that
actual medical devices, such as a guide and catheter may be
inserted to the location-simulated blockage. Fluid may also be
introduced to simulate realistically in vivo conditions. Simulated
heart chambers of similar construction may also be attached to the
aortic valve to enhance further the representation of invasive
procedures.
[0009] More complex simulation systems that provide more accurate,
linked visual and tactile feedback during the training is disclosed
in U.S. Patent Application No. 2003/0069719 published Apr. 10, 2003
that describes an interface device and method for interfacing
instruments to a vascular access simulation system serve to
interface peripherals in the form of mock or actual medical
instruments to the simulation system to enable simulation of
medical procedures. The interface device includes a catheter unit
assembly for receiving a catheter needle assembly, and a skin
traction mechanism to simulate placing skin in traction or
manipulating other anatomical sites for performing a medical
procedure. The catheter needle assembly and skin traction mechanism
are manipulated by a user during a medical procedure. The catheter
unit assembly includes a base, a housing, a bearing assembly and a
shaft that receives the catheter needle assembly. The bearing
assembly enables translation of the catheter needle assembly, and
includes bearings that enable the shaft to translate in accordance
with manipulation of the catheter needle assembly. The shaft
typically includes an encoder to measure translational motion of a
needle of the catheter needle assembly, while the interface device
further includes encoders to measure manipulation of the catheter
needle assembly in various degrees of freedom and the skin traction
mechanism. The simulation system receives measurements from the
interface device encoders and updates the simulation and display,
while providing control signals to the force feedback device to
enable application of force feedback to the catheter needle
assembly.
[0010] Another example for a simulating system that is designed to
simulate an image guiding procedure according to a predefined and
fixed module is disclosed in U.S. Pat. No. 6,538,634 published on
Mar. 25, 2003.
[0011] These simulation systems and other known simulation systems
are based on predefined models, which are acquired and enhanced
before the systems become operational or during a maintenance
thereof, such as updating the system. Usually, a library that
comprises virtual models which are stored in a related database is
connected to the simulation system. During the operational mode,
the system simulates an image-guided procedure according to one of
the virtual models that has been selected by the system user.
[0012] Though such systems allow physicians and trainees to
simulate image-guided procedures, the simulated image-guided
procedures are modeled according to predefined or randomly changed
models of an organ, a human body system, or a section thereof. As
such, the physician or the trainee is trained using a model of a
virtual organ that is not identical to the organ that he or she is
about to perform an operative image-guided procedure on.
[0013] Moreover, when a virtual model is used, the simulation
system cannot be used for accurately simulating an operation that
has been performed on a real patient. Therefore, the currently used
simulation systems cannot be used for going back over an operation
that went wrong or for didactic purposes.
[0014] There is thus a widely recognized need for, and it would be
highly advantageous to have, a system for simulating image-guided
procedures, devoid of the above limitations, that can simulate in a
more realistic manner the image-guided procedure that the physician
is about to perform.
SUMMARY OF THE INVENTION
[0015] According to one aspect of the present invention there is
provided an apparatus for simulating an image-guided procedure. The
apparatus comprises an input for receiving a three-dimensional (3D)
medical image depicting an organ of a patient, a model generation
unit configured for generating a 3D anatomical model of the organ
according to the 3D medical image, and a simulating unit configured
for simulating an image-guided procedure planned for the patient
according to the 3D anatomical model.
[0016] Preferably, the apparatus further comprises a segmentation
unit operatively connected to the model generation unit, the
segmentation unit being configured for segmenting the organ in the
3D medical image to a plurality of areas, the segmented organ image
being used for generating the 3D anatomical model.
[0017] Preferably, the 3D anatomical model is a model of a
tract.
[0018] More preferably, the tract is a member of the following
group: a vascular tract, a urinary tract, a gastrointestinal tract,
and a fistula tract.
[0019] Preferably, the 3D medical image is a member of the
following group: computerized tomography (CT) scan images, magnetic
resonance imager (MRI) scan images, ultrasound scan images, and
positron emission tomography (PET)-CT scan images.
[0020] Preferably, the planned image-guided procedure is an
angioplasty procedure.
[0021] Preferably, the apparatus further comprises a user interface
operatively connected to the model generation unit, the user
interface allows a user to instruct the model generation unit
during the generation of the 3D anatomical model.
[0022] Preferably, the simulated planned image-guided procedure is
used as a study case during a learning process.
[0023] Preferably, the simulated planned image-guided procedure is
used to demonstrate a respective image-guided procedure to the
patient.
[0024] Preferably, the simulated planned image-guided procedure is
used to document preparation to an operation.
[0025] Preferably, the input is configured for receiving a four
dimensional (4D) medical image depicting the organ during a certain
period, the model generation unit configured for generating a 4D
organ model of the organ according to the 4D medical image, the
simulating unit configured for simulating an image-guided procedure
planned for the patient according to the 4D organ model.
[0026] Preferably, the organ is a member of a group comprising: an
anatomical region, a human body system, an area of an organ, a
number of areas of an organ, a section of an organ, and a section
of a human body system.
[0027] According to one aspect of the present invention there is
provided a method for performing a simulated image-guided
procedure. The method comprises the following steps: a) obtaining a
three-dimensional (3D) medical image depicting an organ of a
patient, b) producing a 3D anatomical model of the organ according
to the 3D medical image, and c) simulating an image-guided
procedure planned for the patient according to the 3D model.
[0028] Preferably, the method further comprises a step al) between
step a) and b) of segmenting the organ in the 3D medical image to a
plurality of areas, the producing of step b) is performed according
to the segmented 3D medical image.
[0029] Preferably, the planned image-guided procedure is an
angioplasty procedure.
[0030] Preferably, the producing comprises a step of receiving
generation instructions from a system user, the generation
instructions being used for defining the 3D model.
[0031] Preferably, the simulating comprises displaying the
organ.
[0032] More preferably, the method further comprises a step of
allowing a system user to mark labels for the planned image-guided
procedure according to the display.
[0033] Preferably, the planned image-guided procedure is an
angioplasty procedure.
[0034] Preferably, the simulation is a pre-operative surgical
simulation.
[0035] Preferably, the 3D anatomical model is a model of a
tract.
[0036] Preferably, the 3D anatomical model is a tract model.
[0037] More preferably, the tract model define a member of the
following group: a vascular tract, a urinary tract, a
gastrointestinal tract, and a fistula tract.
[0038] Preferably, the obtaining comprises a step of obtaining a
four dimensional (4D) medical image depicting the organ during a
certain period, the producing comprises a step of producing a 4D
model of the organ according to the 4D medical image, the
simulating is performed according to the 4D model.
[0039] Preferably, the organ is a member of a group comprising: an
anatomical region, a human body system, an area of an organ, a
number of areas of an organ, a section of an organ, and a section
of a human body system.
[0040] Unless otherwise defined, all technical and scientific terms
used herein have the same meaning as commonly understood by one of
ordinary skill in the art to which this invention belongs. The
materials, methods, and examples provided herein are illustrative
only and not intended to be limiting.
[0041] Implementation of the method and system of the present
invention involves performing or completing certain selected tasks
or steps manually, automatically, or a combination thereof.
Moreover, according to actual instrumentation and equipment of
preferred embodiments of the method and system of the present
invention, several selected steps could be implemented by hardware
or by software on any operating system of any firmware or a
combination thereof. For example, as hardware, selected steps of
the invention could be implemented as a chip or a circuit. As
software, selected steps of the invention could be implemented as a
plurality of software instructions being executed by a computer
using any suitable operating system. In any case, selected steps of
the method and system of the invention could be described as being
performed by a data processor, such as a computing platform for
executing a plurality of instructions.
BRIEF DESCRIPTION OF THE DRAWINGS
[0042] The invention is herein described, by way of example only,
with reference to the accompanying drawings. With specific
reference now to the drawings in detail, it is stressed that the
particulars shown are by way of example and for purposes of
illustrative discussion of the preferred embodiments of the present
invention only, and are presented in order to provide what is
believed to be the most useful and readily understood description
of the principles and conceptual aspects of the invention. In this
regard, no attempt is made to show structural details of the
invention in more detail than is necessary for a fundamental
understanding of the invention, the description taken with the
drawings making apparent to those skilled in the art how the
several forms of the invention may be embodied in practice.
[0043] In the drawings:
[0044] FIG. 1 is a schematic representation of a pre-operative
simulator for simulating an image-guided procedure, according to
one preferred embodiment of the present invention;
[0045] FIG. 2A is a graphical representation of the Hounsfield
scale, which measures attenuation of X-Ray radiation by a medium.
Hounsfield values of different human tissues are marked;
[0046] FIGS. 2B and 2C respectively illustrate schematically two
triangular surface models of a femur bone, one directly generated
from scan data, and a coarsened variant of the segment in FIG. 2B
which is generated according to one preferred embodiment of the
present invention;
[0047] FIG. 3 is a schematic representation of the pre-operative
simulator of FIG. 1 with a detailed description of the simulating
unit, according to one embodiment of the present invention;
[0048] FIG. 4 is an exemplary illustration of the pre-operative
simulator of FIG. 3, according to an embodiment of the present
invention;
[0049] FIG. 5 is an exemplary illustration of a screen display
taken during the simulation of an image-guide procedure, according
to an embodiment of the present invention; and
[0050] FIG. 6 is a flowchart of a method for performing a
pre-operative simulation of an image-guided procedure, according to
a preferred embodiment of present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0051] The present embodiments comprise a apparatus and a method
for simulating an image-guided procedure. According to one
embodiment of the present invention, the apparatus and the method
allow a physician to set a pre-operative simulation of an
image-guided procedure. The pre-operative simulation simulates an
image-guided procedure that is about to be performed on a certain
patient. In order to allow such a case-specific simulation, a 3D
medical image that depicts an anatomical region of a certain
patient who is about to be operated on is acquired and 3D
anatomical models are generated based thereupon. Preferably, the 3D
anatomical model defines the boundaries of a certain anatomy or an
organ such as a vascular tract. During the pre-operative
simulation, the 3D anatomical models are used for simulating an
image-guided procedure on that region.
[0052] The principles and operation of an apparatus and method
according to the present invention may be better understood with
reference to the drawings and accompanying description.
[0053] Before explaining at least one embodiment of the invention
in detail, it is to be understood that the invention is not limited
in its application to the details of construction and the
arrangement of the components set forth in the following
description or illustrated in the drawings. The invention is
capable of other embodiments or of being practiced or carried out
in various ways. Also, it is to be understood that the phraseology
and terminology employed herein is for the purpose of description
and should not be regarded as limiting.
[0054] A 3D medical image may be understood as a sequence of CT
scan images, a sequence of MRI scan images, a sequence of PET-CT
scan images, a spatial image, etc.
[0055] A medical imaging system may be understood as an MRI imaging
system, a CT imaging system, a PET-CT imaging system, etc.
[0056] An organ or an anatomical region may be understood as human
body organ, a human body system, an area of an organ, a number of
areas of an organ, a section of an organ, a section of a human body
system, etc.
[0057] Reference is now made to FIG. 1, which is a schematic
representation of a pre-operative simulator 1 for simulating an
image-guided procedure, according to one preferred embodiment of
the present invention. The pre-operative simulator 1 comprises an
input unit 2 for obtaining a 3D medical image that depicts an
anatomy region of a patient and an anatomy-model generation unit 3
that is designed for generating a 3D anatomical model of an organ
according to the received 3D medical image. The pre-operative
simulator 1 further comprises a simulating unit 4 for simulating an
image-guided procedure according to the three-dimensional model, as
described below.
[0058] The input unit 2 preferably allows the system for simulating
image-guided procedure 1 to fetch the 3D medical image from a
medical images server such as a picture archiving communication
system (PACS) before being accessed by the physicians. The PACS
server comprises a number of computers, which are dedicated for
storing, retrieving, distributing and presenting the stored 3D
medical images. The 3D medical images are stored in a number of
formats. The most common format for image storage is digital
imaging and communications in medicine (DICOM). Preferably, the
fetched 3D medical image is represented in a 3D array, preferably
of 512512150 voxels.
[0059] In one embodiment, the input unit 2 receives as input a raw
3D data array, composed as a pre-fetched and pre-parsed DICOM
image. The segmentation is not limited to a specific modality.
Preferably, the 3D medical image is a CT scan. In such an
embodiment, each voxel is represented by a single measured value,
physically corresponding to the degree of X-ray attenuation of a
respective location in the depicted organ. Preferably, the data
acquisition modality is CT-angiography (CTA).
[0060] The input unit 2 may be adjusted to receive the 3D medical
image from a PACS workstation, a computer network, or a portable
memory device such as a DVD, a CD, a memory card, etc.
[0061] The received 3D medical image is forwarded to the
anatomy-model generation unit 3 that is designed for generating the
3D anatomical model, as described above. Preferably, the
anatomy-model generation unit 3 comprises a 3D image segmentation
unit that is used for segmenting the received 3D medical image into
anatomical structures. The segmentation is performed either
automatically or semi-automatically. In one embodiment, a standard
automatic segmentation procedure is used for segmenting the
image.
[0062] Preferably, the segmentation is based on a procedure in
which relevant voxels of the received raw 3D data array are
isolated. For example, if the raw 3D data array is based on a CT
scan, the physical attenuation is scaled in HUs, where the value
-1000 HU is associated with air and the value 0 HU is associated
with water, as shown at FIG. 2A. On such a scale, different tissue
types have different typical HU ranges. The typical attenuation of
a specific tissue is used to isolate it in a 3D array of CT data.
For example, the value of voxels that depict lungs is usually
between -550 HU and -450 HU and the value of voxels that depict
bones is approximately between 450 HU and 1000 HU.
[0063] In such an embodiment, the HU values of voxels of the 3D
medical image are used for isolating the voxels in the tissue of
interest. Preferably, in order to improve precision of the
segmentation procedure, intravenous contrast enhancement (ICE)
components, such as Barium, Iodine or any other radiopharmaceutical
component, are applied when the 3D medical image is taken. The ICE
components increase the HU value of blood vessels to the HU value
of bones and sometimes beyond. Such an increment results in a
higher contrast between the vessel voxels and the surrounding that
can improve the segmentation procedure. Preferably, the
segmentation procedure is adapted to segment a subset of scanned
voxels from the 3D medical image, wherein the stored values of the
voxels in the subset is in a predefined range. In one embodiment,
all the voxels with stored values in the range of blood vessels is
segmented and tagged.
[0064] In one embodiment of the present invention, a triangle mesh
is computed from the raw 3D data array of the HU values.
Preferably, a variant of the marching cubes algorithm is used for
initial generating the triangle mesh, see Marching Cubes: A High
Resolution 3D Surface Construction Algorithm", William E. Lorensen
and Harvey E. Cline, Computer Graphics (Proceedings of SIGGRAPH
'87), Vol. 21, No. 4, pp. 163-169. The triangle mesh is used for
surface construction of segments in the 3D medical image. The mesh
obtained by the variant of the marching cube algorithm bounds the
desired volume of the segment. As the segment is obtained in the
resolution of the 3D medical image, it may be extremely fine.
Therefore, preferably, an additional decimation processing stage is
carried out, in which the mesh is coarsened and the level of
surface approximation of the segments is reduced.
[0065] Preferably, an Edge-Collapse operation is used for the
coarsening, see Hoppe, H. Progressive meshes. In Proc. SIGGRAPH
'96, pages 99-108, August 1996 and Hussain, M., Okada, Y. and
Niijima, K. Fast, simple, feature-preserving and memory efficient
simplification of triangle meshes. International Journal of Image
and Graphics, 3(4):1-18, 2003. An example for such decimation is
depicted in FIGS. 2B and 2C that respectively depict a schematic
illustration a segmented femur bone and a coarsened variant of the
segmented femur bone that has been generated by applying the
aforementioned decimation processing. Preferably, the 3D medical
image is represented in a 3D array of 512.times.512.times.150,
wherein each voxel is preferably represented by a value in one of
the following formats: 8-bit (1 byte storage), 12-bit (2 byte
storage), 16 bit (2 byte storage), and a single-precision floating
point (4 byte storage).
[0066] Preferably, the segmentation procedure is adapted to segment
the anatomy that is depicted in the received 3D medical image.
Different anatomic parts have different characteristics that affect
segmentation.
[0067] During the image-guided procedures, a catheter or the like
is conveyed by a physician via a certain tract. Therefore, the
segmentation procedure's object is to identify such a tract and to
segment it or to segment all the areas that delimit that tract.
[0068] For example, if the received 3D medical image depicts a
cervical portion of the human spine and the image-guided procedure
is an angioplasty procedure, such as carotid stenting, the carotid
artery is the tract through which the catheter or alike is
conveyed. In such a case, the carotid artery should be segmented.
The artery net possesses a-priori known traits that can be
exploited to enhance and verify the fidelity of the segmentation
stage. For example, if the area is a cervical portion and the
procedure is carotid stenting, the following anatomical structures
are exploited: the thoracic aorta, the brachiocephalic trunk, the
Subclavian arteries, the carotid arteries, and the vertebral
arteries.
[0069] Preferably, blood vessels in the image of the organ are
identified and segmented during the segmentation procedure.
Preferably, during the segmentation the centerline, the radius and
the inter-connectivity of each one of the main blood vessels in the
image are identified and registered.
[0070] Preferably, the anatomy-model generation unit 3 is connected
to a user interface (not shown). In such an embodiment, a simulator
user may be asked, for example, to mark one or more points on a
depicted tract. For example, if the received 3D medical image
depicts a cervical portion of the human spine and the image-guided
procedure is an angioplasty procedure, the simulator user may be
required to mark the left carotid artery as a starting point for
the automatic segmentation.
[0071] When the segmentation process is completed, a segmented
version of the 3D image or an array that represents the segmented
areas and the tracts is generated. The segmented areas can be
represented in several formats and sets of data. Preferably, the
segmented 3D image is represented by using one or more of the
following sets of data: [0072] a. A cubic Catmull-Rom 3D spline
description of a central curve of each artery or any other tract
portion; [0073] b. A tree description, graph description or any
other description that describes the connectivity between arteries
or any other tract portions. For example, such a description
describes in which point an artery X emanates an artery Y; [0074]
c. A cubic Catmull-Rom 2D spline description of the radius of each
artery at each point on its central curve; [0075] d. A triangular
surface mesh that describes the surface of the vasculature anatomy;
[0076] e. Polygonal meshes describing other organs captured in the
scan--Lungs, heart, kidneys, etc; and [0077] f. Classification of
each raw data voxel to its designated part of anatomy (a vessel
voxel, a kidney voxel, etc.).
[0078] The segmented 3D medical image or an array representing
segments in the 3D medical image is forwarded to the simulating
unit 4.
[0079] It should be noted that the pre-operative simulator 1 may
also be used to simulate an image-guided procedure according to a
four dimensional (4D) image, which is a set of 3D medical image
that depicts a certain organ during a certain period. In such an
embodiment, a 4D image is received by the input 2. The received 4D
medical image is forwarded to the anatomy-model generation unit 3
that is designed for generating the 4D model. Preferably, the
anatomy-model generation unit 3 comprises a 4D image segmentation
unit that is used for segmenting the received 4D medical image into
anatomical structures. The segmentation is performed either
automatically or semi-automatically. In one embodiment, each one of
the 3D medical image that comprise the received 4D medical image is
separately segmented, as described below.
[0080] Reference is now made to FIG. 3, which is a block diagram
representing the pre-operative simulator 1, which is depicted in
FIG. 1, the components of the simulating unit 4, and a planning
module 51, according to one embodiment of the present
invention.
[0081] The simulating unit 4 preferably comprises two subsystems.
The first subsystem is an intervention simulator device 50
constituted by a dummy interventional instrument 52, motion
detectors 53, a movement calculation unit 57, an image display
device 58, and a force feedback mechanism 54. The second subsystem
is a simulation module 55 that has the functions of receiving
inputs from the motion detectors 53, analyzing the inputs using the
movement calculation unit 57, translating the outcome to visual and
tactile outputs and transferring them to the display device 58 and
to the force feedback mechanism 54. The simulation module 55 has
also the functions of receiving the segmented 3D medical image from
the anatomy-model generation unit 3, wherein the received segmented
3D medical image is already translated to a 3D model that simulates
the organ that is depicted in the segmented 3D medical image. As
described above the segmented 3D medical image is based on a 3D
medical image that is received from the actual patient who is about
to be operated on.
[0082] Reference in now made to FIG. 4, which is an exemplary
illustration of the aforementioned pre-operative simulator 1 for
simulation of an image-guided procedure according to an embodiment
of the present invention. The dummy intervention instrument 52 and
the image display device are as in FIG. 3, however FIG. 4 further
depicts an enclosure 62, a computer processor 64, and a user input
interface 65. In use, a physician prepares himself for the
operative image-guided procedure by manipulating the dummy
interventional instrument 52 that is preferably a dummy catheter.
The dummy interventional instrument 52 is inserted into a cavity 66
within an enclosure 62 that comprises the motion detectors and
force feedback components (not shown), such as resisting force
generators, of the force feedback mechanism (not shown). As the
physician manipulates the dummy interventional instrument 52,
tactile and visual feedbacks are determined according to the
position of dummy interventional instrument 52 within the enclosure
62 in respect to the aforementioned 3D model of the simulated
organ. Visual feedback is provided in the form of a display on the
image display device 58 and tactile feedback is provided from the
force feedback components within the enclosure 62. The visual and
tactile feedbacks, which are respectively displayed on the image
display device 58 and imparted on the dummy interventional
instrument 52 are designed to improve technical and operational
skills of the physician. The visual feedback is given by a display
device 58 that displays a sequence of consecutive images, which are
based on a 3D model that is based on the received 3D medical image.
The tactile feedback is given by imparting different pressures on
the dummy interventional instrument respective to the movement
signals as received from the imaging simulation module, in respect
to the 3D model that is based on the received 3D medical image. The
different pressures simulate the actual tactile feeling the
physician experiences during a real image-guided procedure and
reflects the actual reaction of the patient tissues to the dummy
interventional instrument 52 manipulation.
[0083] The image display device 58 displays a real time feedback
image as transferred from the simulation module (not shown). The
real time feedback image represents a visual image as seen if an
interventional instrument was inserted into the organ of the
patient which is about to be operated on. The visual image is an
accurate and realistic simulation of the visual data that would be
received from the related organ.
[0084] Preferably, the simulation module and the anatomy-model
generation unit 3 are supported by a processor such as an Intel
Pentium Core-Duo, with an nVidia GeForce-6+ (6600 onwards) GPU.
[0085] Reference is now made, once again, to FIG. 3. The simulation
module 55, through the processor, is utilized to prepare simulated
organ visual images as displayed on the screen during the operative
image-guided procedure. The visual feedback is rendered for
simulating a visual display of the organ during the simulated
image-guided procedure, as shown in FIG. 5 that is a simulated
fluoroscopic image of Carotid stenting. Preferably, the simulation
module 55 simulates a number of vascular tracts, according to the
received 3D medical image. At the same time, the simulation module
55 receives navigation signals from the motion detectors 53, which
are located along the enclosure cavity. The simulation module 55
uses the processor to calculate the position of the dummy
interventional instrument 52 within the enclosure cavity according
to the navigation signals and updates the visual image of the
organ, as described above, with the instantaneous respective
position of the dummy interventional instrument 52. Moreover, the
simulation module 55 simulates realistic interaction between the
simulated instrument, such as a catheter, and the simulated
anatomy, including--but not limited to--catheter twist and bend,
vessel flexing and optionally vessel rupture.
[0086] In addition, and in correspondence with the visual
information, the simulation module 55 also instructs the components
of the force feedback 54 to impart pressure on the dummy
interventional instrument 52 in a manner that simulates the
instantaneous tactile feedback of the procedure. Such visual images
and tactile feedback simulate the actual feedback as received
during an actual medical procedure as performed on an actual
subject and therefore reflect to the physician the current location
and bending of the interventional instrument along the simulated
organ. Clearly, the pre-operative simulator 1 is not bound to the
simulation of a particular organ, such as a vascular tract, but can
reflect a visual display of various elements and organs relative to
the instantaneous position of the interventional instrument.
Simulators of image-guided procedures are not described here in
greater detail as they are generally well known and already
comprehensibly described in the incorporated patents and in
publications known to the skilled in the art.
[0087] The pre-operative simulator 1 is designed to allow a
physician to conduct a pre-operative surgical simulation of the
image-guided procedure he or she is about to perform on a certain
patient. In such an embodiment, the physician refers the certain
patient to a medical imaging system for acquiring a 3D medical
image of an organ that is about to be operated on. The acquired 3D
medical image is then forwarded to the PACS server. Later on, the
acquired 3D medical image is obtained by the pre-operative
simulator 1 from the PACS server. The 3D medical image is used as
the basis for a 3D anatomical model of the organ. The 3D anatomical
model is generated by a segmentation unit that is designed for
segmenting the organ into a number of areas, as described in
greater detail above.
[0088] It should be noted that such a pre-operative simulator 1 can
also be used for explaining and demonstrating to the patient the
details of his pathology and the operation he is about to
undergo.
[0089] In one embodiment of the present invention, the
pre-operative simulator 1 can also be used as a learning tool.
Known simulators are designed to simulate an image-guided procedure
on a predefined model of a virtual organ. As the simulated organ is
a virtual organ, the trainer cannot be experienced in diagnosing a
real patient in a manner that allows him to receive a more
comprehensive overview of the related case. As opposed to that, the
pre-operative simulator 1 allows the performance of
patient-specific simulations of real anatomy, as described above.
As such, the pre-operative simulator 1 can be used for teaching a
very real case, with real anatomy, lesions, problems, conflicts and
resolutions. Physicians can experience a more realistic
image-guided procedure, and decisions may be taken during the
simulated image-guided procedure based on the overall medical
history and the medical condition of the patient himself.
[0090] In one embodiment of the present invention, the
pre-operative simulator 1 can also be used as a planning tool. The
planning module 51, which is depicted in FIG. 3, is preferably
connected to the image display device 58 or to any other display
device and to a user interface. The planning module 51 supports
tools for allowing physicians to plan an operative image-guided
procedure according to the aforementioned case-specific simulation.
The module preferably allows the physician to sketch and to take
notes during the image-guided procedure simulation. Preferably, the
image display device 58 is a touch screen that allows the physician
to sketch a track that depicts the maneuvers that he intends to
take during the operative image-guided medical procedure. Moreover,
in such an embodiment, the physician can mark problematic areas of
the depicted organ. In one preferred embodiment, the image-guided
procedure simulation is an angioplasty procedure simulation. The
physician can use the touch screen to sketch the boundaries of the
tract through which he intends to perform the procedure or a
portion thereof.
[0091] In one embodiment of the present invention, the
pre-operative simulator 1 can also be used as an analyzer tool for
going back over performed operations. As described above, the model
of the operated organ is generated according to a medical image of
an organ which is about to be operated. In one embodiment of the
present invention the pre-operative simulator 1 is used for
performing a reenactment of the image-guided procedure that has
been performed on the patient. Such a reenactment is performed as
an image-guided procedure simulation, as described above. As the
model that is used by the pre-operative simulator 1 simulates the
operated on organ, the reenactment is realistic and allows the
physicians to be prepared better to the operation.
[0092] Reference is now made to FIG. 6, which is a flowchart of a
method for performing a simulated image-guided procedure, according
to one embodiment of present invention.
[0093] The method depicted in FIG. 6 allows a physician to conduct
a clinical pre-operative simulation of the image guided procedure
he or she is about to perform. Such a simulation allows the
physician to take safe and unrushed clinical decisions based on a
3D medical image of the patient that is about to be operated
on.
[0094] During the first step, as shown at 201, a 3D medical image
depicting an organ of a patient is obtained. The 3D medical image
has been taken using a medical imaging system and obtained, for
example via a PACS server or a portable memory device, as described
above. The 3D medical image depicts an organ of a patient that is
about to be operated on. During the following step, as shown at
202, a 3D model of the anatomy is produced according to the
received 3D medical image. The 3D model defines the boundaries of
areas in the anatomy such as a certain tract. In the following
step, as shown at 203, a simulation of an image-guided procedure on
the patient is held according to the 3D model that has been
constructed in the previous step. The simulation of the
image-guided procedure allows a physician to prepare himself to the
operative image-guided procedure. Based on the simulation, the
physician can choose the fittest angles and the tools. Furthermore,
the user can mark pitfalls, such as hard-to navigate zones or
misleading view angles in advance.
[0095] For example, if the simulated image-guided procedure is an
angioplasty procedure, the physician can choose, in advance, the
size and the type of the catheter, the balloon, and the stent he is
going to use during the operation. Moreover, gaining acquaintance
with the specific anatomy of the patient in advance may result in
reducing contrast injection and X-ray exposure. In angioplasty
procedure, for example, the duration of the X-ray exposure periods
depends on the time it takes the physician to maneuver the catheter
in the relevant anatomy region. If the physician already simulated
the angioplasty procedure using the aforementioned system, he is
already familiar with the specific region and therefore can easily
maneuver the catheter during the actual angioplasty procedure.
[0096] It is expected that during the life of this patent many
relevant devices and systems will be developed and the scope of the
terms herein, particularly of the terms a 3D model, an imaging
device, a simulating unit, motion detectors, a 3D medical image,
and an image-guided procedure are intended to include all such new
technologies a priori.
[0097] It is appreciated that certain features of the invention,
which are, for clarity, described in the context of separate
embodiments, may also be provided in combination in a single
embodiment. Conversely, various features of the invention, which
are, for brevity, described in the context of a single embodiment,
may also be provided separately or in any suitable
subcombination.
[0098] Although the invention has been described in conjunction
with specific embodiments thereof, it is evident that many
alternatives, modifications and variations will be apparent to
those skilled in the art. Accordingly, it is intended to embrace
all such alternatives, modifications and variations that fall
within the spirit and broad scope of the appended claims. All
publications, patents, and patent applications mentioned in this
specification are herein incorporated in their entirety by
reference into the specification, to the same extent as if each
individual publication, patent or patent application was
specifically and individually indicated to be incorporated herein
by reference. In addition, citation or identification of any
reference in this application shall not be construed as an
admission that such reference is available as prior art to the
present invention.
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