U.S. patent application number 13/975822 was filed with the patent office on 2013-12-26 for modeling device, program, computer-readable recording medium, and method of establishing correspondence.
This patent application is currently assigned to JAPAN SCIENCE AND TECHNOLOGY AGENCY. The applicant listed for this patent is Toshiaki HISADA, Hiroshi KUROKAWA, Jun-Ichi OKADA, Nobuhiko OSHIDA, Seiryo SUGIURA, Takumi WASHIO, Hiroshi WATANABE, Masafumi YAMAMOTO. Invention is credited to Toshiaki HISADA, Hiroshi KUROKAWA, Jun-Ichi OKADA, Nobuhiko OSHIDA, Seiryo SUGIURA, Takumi WASHIO, Hiroshi WATANABE, Masafumi YAMAMOTO.
Application Number | 20130342217 13/975822 |
Document ID | / |
Family ID | 36740379 |
Filed Date | 2013-12-26 |
United States Patent
Application |
20130342217 |
Kind Code |
A1 |
HISADA; Toshiaki ; et
al. |
December 26, 2013 |
MODELING DEVICE, PROGRAM, COMPUTER-READABLE RECORDING MEDIUM, AND
METHOD OF ESTABLISHING CORRESPONDENCE
Abstract
A modeling device is disclosed that easily projects
characteristic information obtained from an object onto a
differently-shaped object, even if the object, from which the
characteristic information is obtained, has a complex shape. A
modeling device in one embodiment of the present invention includes
a virtually electrifying section to calculate an electric potential
at a spot in a heart at the time when a predetermined voltage is
applied to the heart, and a projecting section to project a fiber
orientation onto a heart model created on the basis of shape
information that is input to the input section. The projecting
section specifies a spot to be a target of projection on the basis
of the electric potential obtained by the virtually electrifying
section. Use of the electric potential in specifying the spot makes
it possible to easily project the fiber orientation onto any heart
having complex and various shapes.
Inventors: |
HISADA; Toshiaki; (Tokyo,
JP) ; KUROKAWA; Hiroshi; (Tokyo, JP) ; OSHIDA;
Nobuhiko; (Tokyo, JP) ; YAMAMOTO; Masafumi;
(Tokyo, JP) ; WASHIO; Takumi; (Tsukuba-shi,
JP) ; OKADA; Jun-Ichi; (Kashiwa-shi, JP) ;
WATANABE; Hiroshi; (Tokyo, JP) ; SUGIURA; Seiryo;
(Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
HISADA; Toshiaki
KUROKAWA; Hiroshi
OSHIDA; Nobuhiko
YAMAMOTO; Masafumi
WASHIO; Takumi
OKADA; Jun-Ichi
WATANABE; Hiroshi
SUGIURA; Seiryo |
Tokyo
Tokyo
Tokyo
Tokyo
Tsukuba-shi
Kashiwa-shi
Tokyo
Tokyo |
|
JP
JP
JP
JP
JP
JP
JP
JP |
|
|
Assignee: |
JAPAN SCIENCE AND TECHNOLOGY
AGENCY
Saitama
JP
|
Family ID: |
36740379 |
Appl. No.: |
13/975822 |
Filed: |
August 26, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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13314534 |
Dec 8, 2011 |
8554491 |
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13975822 |
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11795888 |
Jul 24, 2007 |
8095321 |
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PCT/JP2006/301142 |
Jan 25, 2006 |
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13314534 |
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Current U.S.
Class: |
324/649 |
Current CPC
Class: |
G06T 11/206 20130101;
G16H 50/50 20180101 |
Class at
Publication: |
324/649 |
International
Class: |
G06F 19/00 20060101
G06F019/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 26, 2005 |
JP |
2005-18949 |
Claims
1.-8. (canceled)
9. A method of establishing a correspondence between a spot in a
first object and a spot in a second object, the method comprising:
obtaining (i) an electric potential distribution at a time when a
predetermined voltage is applied to the first object and (ii) an
electric potential distribution at a time when the predetermined
voltage is applied to the second object; and establishing, on a
basis of the electric potential distribution obtained, the
correspondence between the spot in the first object and the spot in
the second object.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of and claims priority
under 35 U.S.C. .sctn..sctn.120/121 to U.S. patent application Ser.
No. 13/314,534, filed on Dec. 8, 2011, which is a divisional of and
claims priority under 35 U.S.C. .sctn..sctn.120/121 to U.S. patent
application Ser. No. 11/795,888, filed on Jul. 24, 2007, which is a
National Stage of International Application No. PCT/JP2006/301142,
filed on Jan. 25, 2006, which claims the benefit of Japanese Patent
Application No. 2005-018949, filed on Jan. 26, 2005. The
disclosures of each of the above applications are hereby
incorporated herein by reference in their entirety.
TECHNICAL FIELD
[0002] The present invention relates to a modeling device, a
program, and a computer-readable recording medium, and
particularly, relates to a modeling device virtually forming an
object model, a program used in the modeling device, and a
computer-readable recording medium storing the program. The present
invention also relates to a method of establishing a correspondence
between an object and another object.
BACKGROUND ART
[0003] A heart contracts and relaxes, that is to say, beats at a
regular rhythm. Arrythmia is a serious disease that a period of
this cardiac beat becomes irregular, sometimes causing cardiac
arrest. Various and detailed studies have been carried out on the
cardiac beat mechanism for medical treatment and diagnosis of
arrythmia.
[0004] Cardiac contraction occurs as follows. First, electrical
impulses are emitted at a constant period from a part of a right
atrium, which part is called a sinoatrial node. The electrical
impulses are passed to cardiac muscle cells of the right atrium and
cardiac muscle cells of a left atrium. Consequently, myofibrils in
the cardiac muscle cells contract. When this contraction of the
myofibrils occurs all over the right atrium and the left atrium,
the right atrium and the left atrium are caused to contract.
Further, a part of the electrical impulses reaches an
atrioventicular node located below the right atrium and in the
vicinity of an interventricular septum. After reaching the
atrioventicular node, the impulses pass through His bundles, right
and left bundle branches, and Purkinje fibers, and then reach a
left ventricle and a right ventricle, causing the left ventricle
and the right ventricle to contract. As the foregoing discusses, a
cardiac beat is caused by electrical impulses passing through the
heart.
[0005] The cardiac muscle cells are in the shape of a cylinder with
a diameter of approximately 5 to 20 .mu.m and a length of
approximately 100 .mu.m. The cardiac muscle cells are arranged in a
certain orientation to form a bundle. An orientation of the length
of the cardiac muscle cells is same as that of the myofibrils in
the cells, and therefore is called a fiber orientation. Muscle
contraction is caused by sliding movement of the myofibrils. The
fiber orientation is closely related to cardiac contraction
movement. Therefore, the fiber orientation is an important factor
in mechanically analyzing the cardiac contraction. Further, an
electric current passes easily in the fiber orientation in the
cells. The fiber orientation relates to a conduction orientation of
the electrical impulses in the heart. Therefore, the fiber
orientation is an important factor also in analyzing conduction
pathways of the electrical impulses in the heart.
[0006] It is empirically known that appropriate fiber placement is
important for efficient cardiac contraction and blood pulsation.
The fiber orientation varies in different parts. The fiber
orientations of the entire heart are complex. Conventionally, the
fiber orientation is measured by anatomical and histological
methods. In view of ethics, a heart of a dog or a pig, which are
relatively close to a human, is utilized in place of a human
heart.
[0007] For example in Documents 1, 2, the fiber orientation and the
sheet orientation of a pig heart are measured, and this measured
fiber orientation data is organized with introduction of three
coordinate systems, such as an ellipse coordinate system, and
Hermitian finite element. The sheet orientation is in connection
with a plane (sheet) where the cardiac muscle cells are arranged.
Mathematically, the sheet orientation is vertical to the plane.
[0008] Documents 3 and 4 disclose a method of measuring and
calculating a fiber orientation with the use of diffusion tensor
magnetic resonance imaging (MRI). A spatial distribution of the
fiber orientation of a dog heart is actually obtained, and is
compared with histological data for verification.
[0009] The foregoing results of measurement have roughly clarified
a pattern of the fiber placement in the heart. Findings from
animals are utilized to creates a virtual human heart model in a
calculator, and attempts to contribute to medical care and drug
discovery have been made by simulations and the like.
[0010] However, no modeling device has been realized by which
information on the fiber orientation of the cardiac muscle cells,
which information is obtained from an animal, is buried in a human
heart to perform modeling suitably. This is due to the following
reasons.
[0011] First, no coordinate system suitable to specify the spots in
a heart has not been found. For example, to apply a fiber
orientation obtained from animal onto a human heart model, it is
necessary to establish a one-by-one correspondence between a spot
in the animal heart and a spot in the human heart. However, the
shapes of the hearts vary among species, and further, among
individuals. Furthermore, the shapes of the hearts are very
complex. Therefore, it is extremely difficult with an ordinary
XYZ-axes orthogonal coordinate system or the like to set a
correspondence between spots of two different hearts. In view of
the foregoing circumstances, there have been demands for a modeling
device by which characteristic information, such as a fiber
orientation, obtained from an object is easily projected onto a
differently-shaped object, even if the shape of the object, from
which the characteristic information is obtained, is complex, such
as the shape of a heart.
[0012] Further, no method of suitably setting a local coordinate
system to define the fiber orientation and the like at a spot in a
heart has been found. The fiber orientation, for instance, is
closely related to the outer shape of the heart. For example, the
fiber orientation at a point on a surface of the epicardium of the
heart is included within a plane that is in contact with the point.
However, if the fiber orientation information is expressed with the
use of an ordinary global coordinate system, it is not possible to
express the fiber orientation in such a way as to correspond to the
outer shape of the heart, because the global coordinate system has
no relationship with the outer shape of the heart. Therefore, if
the fiber orientation data obtained from animals is directly
applied to the human heart, contradiction may arise in the fiber
orientation. For example, the fiber orientation protrudes from the
epicardium of the heart. Further, even if a hypothesis about the
fiber orientation on the basis of the findings obtained from the
animal heart is to be applied, it is not possible to apply the
hypothesis naturally. In view of the foregoing reasons, the local
coordinate system needs to be set at respective spots in the heart.
The heart, however, has a very complex shape. Setting the local
coordinate system by performing a geometric calculation each time
on the basis of the shape of the heart requires a vast amount of
calculation and is therefore not realistic. In view of the
foregoing circumstances, there have been demands for a modeling
device by which orientation characteristic information, such as a
fiber orientation, that is related to an outer shape of a heart is
easily projected from an object onto another object.
[0013] (Document 1)
[0014] Stevens C, Hunter P J. Sarcomere length changes in a 3D
mathematical model of the pig ventricles. Prog Biophys Mol Biol.
2003 May-July; 82(1-3): 229-241.
[0015] (Document 2)
[0016] Stevens C, Remme E, LeGrice I, Hunter P. Ventricular
mechanics in diastole: material parameter sensitivity. J Biomech.
2003 May; 36(5): 737-748.
[0017] (Document 3)
[0018] Scollan D F, Holmes A, Winslow R, Forder J. Histological
validation of myocardial microstructure obtained from diffusion
tensor magnetic resonance imaging. Am J Physiol. 1998 December;
275(6 Pt 2): H2308-H2318.
[0019] (Document 4)
[0020] Scollan D F, Holmes A, Zhang J, Winslow R L. Reconstruction
of cardiac ventricular geometry and fiber orientation using
magnetic resonance imaging. Ann Biomed Eng. 2000 August; 28(8):
934-944.
DISCLOSURE OF INVENTION
[0021] The present invention is in view of the foregoing problems,
and has as a main object to realize a modeling device by which
characteristic information obtained from an object is easily
projected onto a differently-shaped object, even if the object,
from which the characteristic information is obtained, has a
complex shape.
[0022] Another object of the present invention is to realize a
modeling device by which orientation characteristic information is
easily projected from an object onto another object, which
information is related to the shape of the object.
[0023] To solve the above problems, a modeling device of the
present invention is adapted so that the modeling device includes:
a first input section to which shape information on an object is
input; a second input section to which characteristic information
is input, the characteristic information indicating a
correspondence between a spot in the object and a characteristic;
virtually electrifying means for obtaining by calculation, on a
basis of the shape information that is input to the first input
section, an electric potential at a spot in the object at a time
when a predetermined voltage is applied to the object; and
projecting means for projecting, onto an object model based on the
shape information that is input to the first input section, the
characteristic contained in the characteristic information that is
input to the second input section, the projecting means specifying
a spot in the object model on a basis of the electric potential
obtained by the virtually electrifying means, onto which spot the
characteristic is to be projected.
[0024] The characteristic information that is input to the second
input section contains a correspondence between the spot in the
object and the characteristic. The projecting means projects the
characteristic information onto the object model that is input to
the first input section. Thus, the characteristic corresponding to
the spot is projected onto the object model. The "spot" may be
either of a point and an area.
[0025] A spot in the object is specified on the basis of the
electric potential obtained by the virtually electrifying means.
The virtually electrifying means virtually applies the
predetermined voltage. Therefore, the electric potential at a spot
in the object is in the range of 0V to the predetermined voltage.
Accordingly, a spot in the object is specified in the range of 0V
to the predetermined voltage. This makes it possible to specify the
spot in various objects having different shapes by use of a common
scale (not smaller than 0V and not greater than the predetermined
voltage). Accordingly, for example a function with a variable of a
coordinate based on the electric potential is input to the second
input section as the characteristic information, the characteristic
is easily projected regardless of shape of a target object. In
other words, with the modeling device of the present invention, the
characteristic is projected onto various objects having different
shapes. Further, no geometric calculation is necessary to specify
the spot, so that the characteristic is easily projected onto an
object even if the object has a complex shape.
[0026] To solve the above problems, a different modeling device of
the present invention is adapted so that the modeling device
includes: a first input section to which shape information on a
first object is input; a second input section to which
characteristic information is input, the characteristic information
containing a spot in the second object and a characteristic at the
spot; a third input section to which shape information on the
second object is input; virtually electrifying means for obtaining
by calculation, on a basis of the shape information that is input
to the first input section and the shape information that is input
to the third input section, (i) an electric potential at a spot in
the first object at a time when a predetermined voltage is applied
to the first object and (ii) an electric potential at a spot in the
second object at a time when the predetermined voltage is applied
to the second object; and projecting means for: specifying, on a
basis of the electric potential obtained by the virtually
electrifying means, a spot in the first object model based on the
shape information that is input to the first input section, the
spot in the first object model corresponding to the spot in the
second object, and the spot in the second object being contained in
the characteristic information that is input to the second input
section; and projecting the characteristic onto the spot.
[0027] With this configuration, the virtually electrifying means
applies the voltage to obtain the electric potential at a spot in
the first object. In the same manner, the virtually electrifying
means obtains the electric potential at a spot in the second
object. Then, the projecting means establishes a correspondence
between the spot in the second object and the spot in the first
object model on the basis of the electric potential at the spot in
the second object. For example, the projecting means establishes a
correspondence between the spot in the second object and the spot,
having a same electric potential as that of the spot in the second
object, in the first object model. Thereafter, the projecting means
projects the characteristic information on the spot in the second
object, which characteristic information is input to the second
input section, onto the corresponding spot in the first object
model. By the foregoing way, the characteristic information on a
spot in the second object is projected onto the corresponding spot
in the first object.
[0028] The projecting means establishes the correspondence between
the spot in the first object and the spot in the second object on
the basis of the electric potential obtained by the virtually
electrifying means. The virtually electrifying means applies the
predetermined voltage. Therefore, the electric potential at a spot
in the objects is in the range of 0V to the predetermined voltage.
Accordingly, a spot in each of the objects is specified in the
range of 0V to the predetermined voltage. This makes it possible to
easily establish a correspondence by use of a common scale (not
smaller than 0V and not greater than the predetermined voltage)
even if the shape of the first object and the shape of the second
object are complex and different. Accordingly, with the modeling
device of the present invention, characteristic information
obtained from an object is easily projected onto a
differently-shaped object, even if the object, from which the
characteristic information is obtained, has a complex shape.
Further, no geometric calculation is necessary to establish a
correspondence between spots, so that the characteristic is easily
projected even if the shape of the object is complex.
[0029] Respective means of the modeling device may be realized by
hardware, or may be realized by causing a computer to execute a
program. Specifically, a program of the present invention causes a
computer to operate as the respective means of any one of the
modeling devices described above. Further, a recording medium of
the present invention stores the program.
[0030] Executing the program, the computer operates as the
respective means of the modeling device. This realizes a modeling
device by which characteristic information obtained from an object
is easily projected onto a differently-shaped object, even if the
object, from which the characteristic information is obtained, has
a complex shape.
[0031] To solve the above problems, a method of establishing a
correspondence according to the present invention is adapted so
that the method includes: obtaining (i) an electric potential
distribution at a time when a predetermined voltage is applied to
the first object and (ii) an electric potential distribution at a
time when the predetermined voltage is applied to the second
object; and establishing, on a basis of the electric potential
distribution obtained, the correspondence between the spot in the
first object and the spot in the second object.
[0032] With this arrangement, the correspondence between the points
or areas in the objects is established on the basis of the electric
potential distribution. The electric potential distribution is a
distribution at a time when the predetermined voltage is applied.
Therefore, any spot in the objects is in the range of 0V to the
predetermined voltage. Accordingly, any spot in the objects is
specified in the range of 0V to the predetermined voltage. The
foregoing arrangement makes it possible to establish a
correspondence between the points or areas by use of a common scale
(not smaller than 0V and not greater than predetermined voltage),
even if the shapes of the first object and the second object are
different.
[0033] Additional objects, features, and strengths of the present
invention will be made clear by the description below. Further, the
advantages of the present invention will be evident from the
following explanation in reference to the drawings.
BRIEF DESCRIPTION OF DRAWINGS
[0034] FIG. 1 This is a functional block diagram showing a
configuration of a main part of a modeling device to illustrate an
embodiment of the present invention.
[0035] FIG. 2 This is a flowchart showing a process sequence of the
modeling device shown in FIG. 1.
[0036] FIG. 3 This is a flowchart showing a process sequence of
calculation in an electric-potential orientation and an electric
current orientation, which process sequence is a part of the
sequence shown in FIG. 2.
[0037] FIG. 4 This is a figure showing longitude orientation
vectors calculated at respective spots.
[0038] FIG. 5 This is a figure showing depth-orientation vectors
calculated at respective spots.
[0039] FIG. 6 This is a figure showing latitude orientation vectors
calculated at respective spots.
[0040] FIG. 7 This is a figure showing a local coordinate system to
define a fiber orientation.
[0041] FIGS. 8(a) to 8(e) are figures each showing fiber placement
reproduced on a human heart model by a modeling device of an
embodiment of the present invention.
[0042] FIG. 9 This is a functional block diagram showing a
configuration of a main part of a modeling device to show another
embodiment of the present invention.
[0043] FIG. 10 This is a flowchart showing a process sequence of
the modeling device shown in FIG. 9.
[0044] FIG. 11 This is a figure showing an apex--base electric
potential distribution.
[0045] FIG. 12 This is a figure showing an endocardium--epicardium
electric potential distribution.
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiment 1
[0046] The following describes an embodiment of the present
invention, with reference to FIGS. 1 to 8. In the present
embodiment, an exemplary case is discussed in which an object is a
human heart, and a characteristic employed is a characteristic
regarding a fiber orientation of cardiac muscle cells.
Specifically, a modeling device that suitably projects a hypothesis
regarding the fiber orientation of the cardiac muscle cells onto a
human heart model (more specifically, left ventricle model and
right ventricle model) and reproduces a fiber orientation based on
the hypothesis is described in the present embodiment.
[0047] FIG. 1 is a functional block diagram of a modeling device 1
of the present embodiment. The modeling device 1 includes an input
section (first input section, second input section) 10, a
reconstructing section 11, a virtually electrifying section
(electrifying means, virtually electrifying means) 12, a projecting
section (projecting means) 13, a geometry section (geometry means)
14, a display section 15, and a storage section 16.
[0048] Shape information on the human heart and a function
indicating a relationship between a spot and a fiber orientation in
the human heart are input into the input section 10. The input
section 10 is not particularly limited. For example, a various data
input interface which reads data from an external storage device, a
keyboard with which a user inputs information by operating keys, or
the like is used as the input section 10. The modeling device 1 may
include a plurality of input sections, and the shape information
and the function may be input into different input sections.
[0049] An example of the shape information of the human heart is a
continuous tomography image taken with the use of X-ray CT (X-ray
computed tomography) or MRI (magnetic resonance imaging). With
these methods, the shape information on the heart is obtained in a
non-invasive manner. Further, if obtained in advance, polygon
coordinate data constituting the heart model may be utilized in
place of the continuous tomography image. The function will be
described concretely later.
[0050] The reconstructing section 11 reconstructs the heart model
by converting the shape information on the human heart, which shape
information is input to the input section, into the polygon
coordinate data constituting the heart model. The reconstructing
section 11 may be omitted in a case in which polygon coordinates
are utilized as shape data of the human heart.
[0051] The virtually electrifying section 12 virtually applies a
predetermined voltage to the human heart based on the shape
information that is input to the input section 20, and obtains an
electric potential and/or electric current orientation by
calculation. Concretely, the virtually electrifying section 12
virtually applies a voltage to the heart model reconstructed
three-dimensionally by the reconstructing section 11, and
calculates the electric potential and the electric current
orientation at respective spots in the heart model. In the present
embodiment, the virtually electrifying section 12 virtually applies
the voltage and calculates the electric potential and the electric
current orientation by the method described below. Alternatively,
an electrifying section (electrifying means) may be provided in
place of the virtually electrifying section 12 so as to actually
apply a voltage to a target object, such as a heart, and obtains
the electric potential and the electric current orientation based
on actually-measured values.
[0052] The projecting section 13 projects, onto the human heart
model based on the shape information that is input to the input
section, the fiber orientation contained in the function that is
input to the input section. The fiber orientation is projected at a
spot contained in the characteristic information. Concretely, the
projecting section 13 projects the fiber orientation onto the human
heart model reconstructed by the reconstructing section 11. To
specify the spot at the time of projection, the projecting section
13 utilizes the electric potential obtained by the virtually
electrifying section 12.
[0053] The geometry section 14 performs a geometry process on the
human heart model on which the fiber orientation is projected by
the projecting section 13. The geometry process is to convert a
coordinate system defining the heart model from a modeling
coordinate system to a visual coordinate system with a viewpoint
being an origin of the visual coordinate system. The geometry
process includes calculation of various effects such as perspective
rules to perform conversion for projection, and conversion into a
screen coordinate system so that the human heart model fits in a
screen on which the human heart model is to be displayed.
[0054] The display section 15 displays images of the heart model on
which the geometry process is performed by the geometry section 14.
A CRT (cathode-ray tube), a liquid crystal display, or the like is
employed as the display section 15.
[0055] The storage section 16 stores: coordinate data of the heart
model reconstructed by the reconstructing section 11; and data of
the electric potential and the electric current orientation at
respective spots in the heart model, which electric potential and
the electric current orientation are obtained by the virtually
electrifying section. Specifically, the storage section 16 stores
the following data described below: polygon coordinate data 50;
apex--base electric potential distribution 51;
endocardium--epicardium electric potential distribution 52;
longitude orientation data 53; latitude orientation data 54;
corrected depth data 55; and the like. The storage section 16 is
constituted of various memories such as RAM (Random Access
Memory).
[0056] The reconstructing section 11, the virtually electrifying
section 12, the projecting section 13, and the geometry section 14
may be constituted solely of hardware such as dedicated IC, or may
be constituted of a combination of hardware and software such as a
combination of a CPU, a memory, and a program.
[0057] The following describes operation of the modeling device 1
of the present embodiment. FIG. 2 is a flowchart showing a process
sequence of the modeling device 1.
[0058] First, the shape information on the human heart is input
into the input section 10 of the modeling device 1 (step S100). In
the present embodiment, an exemplary case is described in which the
shape information to be input is a series of continuous tomography
images taken with MRI. In this case, a heart image taken
continuously along a line extending in vertical orientation of the
heart (base--apex orientation) may be utilized as the continuous
tomography images.
[0059] These input continuous tomography images are output to the
reconstructing section 11. The reconstructing section 11
reconstructs the heart on the basis of the continuous tomography
images to create the heart (more specifically, the left ventricle
and the right ventricle) model (step S101). Specifically, when the
continuous tomography images are input, the reconstructing section
11 performs image processing to extract borders (outlines) of
endocardium and epicardium of the heart in respective tomography
images. Then, correction of the outlines is performed on a part
between one tomography image and the following tomography image.
Consequently, a three-dimensional heart model is created on the
basis of the continuous tomography image. Then, the reconstructing
section 11 saves this obtained polygon coordinate data 50 of the
heart model so that the polygon coordinate data 50 is stored in the
storage section 16. Hereinafter, the coordinate system defining the
polygon coordinate will be referred to as the modeling coordinate
system. Step S101 may be omitted in a case in which the shape
information input in step S100 is the polygon coordinate data.
[0060] The polygon coordinate data 50 stored in the storage section
16 is read out by the virtually electrifying section 12. The
virtually electrifying section 12 virtually electrifies the heart
model having read the coordinate data from the storage section 16,
and calculates the electric potential and an orientation at
respective spots in the heart model, in which orientation the
electric current flows (the orientation will be referred to as
"electric current orientation" hereinafter) (step S102).
[0061] FIG. 3 shows details of step S102. First, the virtually
electrifying section 12 virtually applies a voltage of 1V between
an apex and a base of the heart model. In the present embodiment,
the apex is a negative terminal, and the base is a positive
terminal. Accordingly, the electric potential of the apex is 0V.
The electric potential increases from the apex toward the base. The
electric potential of the base is 1V. The virtually electrifying
section 12 calculates an electric potential at respective spots in
the heart model at the time when the voltage is applied between the
apex and the base (the electric potential will be referred to as
"apex--base electric potential" hereinafter) (step S1021). A
publicly-known method may be utilized to calculate the electric
potential at a spot in the heart model. An exemplary method is
solving the Poisson Equation by use of a finite element method. The
electric potential may be calculated by use of market-available
software such as MSC Nastran (registered trademark, manufactured by
MSC software corporation). The virtually electrifying section 12
then saves this calculated apex--base electric potential
distribution 51 so that the apex--base electric potential
distribution 51 is stored in the storage section 16. The apex--base
electric potential distribution 51, concretely, is correspondence
information indicating a correspondence between the coordinate
defined in the modeling coordinate system and the apex--base
electric potential. For reference, a visualized calculated
apex--base electric potential distribution 51 is shown in FIG. 11.
As shown in this figure, the electric potential slops from the apex
toward the base. The apex--base electric potential is utilized as
one of the coordinates (electric potential coordinate) to specify a
spot in the heart model. Although the exemplary case in which the
virtually electrifying section 12 applies the voltage of 1V in the
present embodiment, the voltage to be applied may be any voltage as
long as it is a constant voltage.
[0062] Then, the virtually electrifying section 12 calculates, for
respective spots in the heart, an orientation in which the electric
current flows at the time when the voltage is applied between the
apex and the base (the orientation will be referred to as
"longitude orientation" hereinafter) (step S1022). The electric
current flows in an orientation in which the electric potential
slopes most steeply. Therefore, the longitude orientation is
calculated by use of the electric potential distribution obtained
in step S1021. The longitude orientation thus calculated is stored,
as the longitude orientation data 53, into the storage section 16
by the virtually electrifying section 12. Specifically, components
of vectors of the longitude orientation, which components are
written in the modeling coordinate system, are stored in the
storage section 16. FIG. 4 shows longitude orientation vectors
calculated at respective spots. The longitude orientation is a
first coordinate axis in a local coordinate system at respective
spots in the heart model.
[0063] Then, in the same manner as in step S1021, the virtually
electrifying section 12 virtually applies the voltage of 1V between
the endocardium and the epicardium of the heart model. The left
ventricle model and the right ventricle model are employed as the
heart model in the present embodiment, so that the same operation
is performed on each of a left ventricle and a right ventricle. In
the present embodiment, the endocardium is the negative terminal,
and the epicardium is the positive terminal. Accordingly, the
electric potential of the endocardium is 0. The electric potential
increases from the endocardium toward the epicardium. The electric
potential of the epicardium is 1V. The virtually electrifying
section 12 calculates the electric potential at respective spots in
the heart model at the time when the voltage is applied between the
endocardium and the epicardium (the electric potential will be
referred to as "endocardium--epicardium electric potential"
hereinafter) (S1023). A visualized calculated
endocardium--epicardium electric potential distribution 52 is shown
in FIG. 12 as an example. As shown in this figure, the electric
potential slops from the endocardium toward the epicardium. The
endocardium--epicardium electric potential distribution 52 thus
calculated for each of the spots is stored into the storage section
16 by the virtually electrifying section 12. The
endocardium--epicardium electric potential distribution 52,
concretely, is correspondence information indicating a
correspondence between the coordinate defined in the modeling
coordinate system and the endocardium--epicardium electric
potential. The endocardium--epicardium electric potential is
utilized as one of the coordinates to specify a spot in the heart
model.
[0064] Then, in the same manner as in step S1022, the virtually
electrifying section 12 calculates, for each of the right ventricle
and the left ventricle, an orientation in which the electric
current flows at the time when the voltage is applied between the
endocardium and the epicardium (the orientation will be referred to
as "depth orientation" hereinafter) (step S1024). FIG. 5 shows
depth-orientation vectors calculated for the left ventricle.
[0065] Thereafter, the virtually electrifying section 12 calculates
a cross product of the vector in the longitude orientation as shown
in FIG. 4 and the vector in the depth orientation as shown in FIG.
5, thereby calculating, for respective spots in the heart, a vector
orthogonal to either of the longitude orientation and the depth
orientation (the vector will be referred to as
"latitude-orientation vector" hereinafter) (step S1025). The
latitude orientation thus calculated is stored, as the latitude
orientation data 54, into the storage section 16 by the virtually
electrifying section 12. The latitude orientation data 54,
concretely, defines components of the latitude-orientation vector
in the modeling coordinate system. FIG. 6 shows the
latitude-orientation vector thus calculated. The latitude
orientation is a second coordinate axis in the local coordinate
system at respective spots in the heart model.
[0066] Consequently, those three orientations are obtained: the
longitude orientation; the depth-orientation; and the latitude
orientation. In some cases, the longitude orientation and the depth
orientation are not perfectly orthogonal. It is thus necessary to
correct the depth orientation so that the depth orientation becomes
perfectly orthogonal to the longitude orientation. In other words,
the virtually electrifying section 12 calculates a cross product of
the vector in the longitude orientation and the vector in the
latitude-orientation vector to calculate, for respective spots in
the heart, a vector orthogonal to either of the longitude
orientation and the latitude orientation (the vector will be
referred to as "corrected depth-orientation vector" hereinafter)
(step S1026). This corrected depth orientation is substantially
equal to the depth orientation obtained in step S1024, but is
perfectly orthogonal to either one of the longitude orientation and
the latitude orientation. The corrected depth orientation thus
calculated is stored, as the corrected depth orientation data 55,
into the storage section 16 by the virtually electrifying section
12. The corrected depth orientation data 55, concretely, defines
components of the corrected depth-orientation vector in the
modeling coordinate system. The corrected depth orientation is a
third coordinate axis in the local coordinate system at respective
spots in the heart model. The foregoing describes calculation of
the electric potential and the electric current orientation by the
virtually electrifying section 12.
[0067] The fiber orientation at respective spots in the heart model
are defined as angle components in the local coordinate system
constituted of the longitude orientation, the latitude orientation,
and the corrected depth-orientation. The modeling device 1 defines
the fiber orientation by use of the local coordinate system,
whereby the fiber orientation is defined in such a manner that a
correspondence is established between the fiber orientation and an
outer shape of the heart. This allows the fiber orientation to be
projected onto the heart model in such a way as to fit in the outer
shape of this target heart model.
[0068] Further, to specify a spot in the heart model, a rotation
angle is set as the third coordinate, in addition to the apex--base
electric potential and the endocardium--epicardium electric
potential. The rotation angle is an angle in a rotation orientation
having a central axis passing through the apex and the base. The
rotation angle is defined with a characteristic spot in the heart
being a base point. The characteristic spot only needs to be
identifiable regardless of individuals or species and clearly
distinguishable. In the present embodiment, an exemplary case is
discussed in which a long axis in the orientation between the apex
and the base of the left ventricle is a center, an orientation of a
most protruded part of the right ventricle is 0.degree., and an
anticlockwise orientation from the viewpoint of the base is a
positive angle. The foregoing allows the modeling device 1 of the
present embodiment to specify a spot on the object by the following
three coordinates: the apex--base electric potential (0-1); the
endocardium--epicardium electric potential (0-1); and the rotation
angle (0-2.pi.). Hereinafter, these coordinates will be referred to
as electric potential coordinates, and this coordinate system will
be referred to as an electric potential coordinate system. With
this arrangement, spots in hearts of various shapes and sizes are
specified by use of a common coordinate, which is the electric
potential coordinate.
[0069] Then, the modeling device 1 requests an input of a function,
which is a hypothesis regarding the fiber orientation. The function
is supplied from the input section 10 as the characteristic
information (step S103 in FIG. 2). The timing of the input of the
function does not necessarily have to be after the virtually
electrifying section calculates the electric potential and the
electric current orientation. For example, the function may be
input concurrently with inputting the shape information on the
human heart.
[0070] The following describes an exemplary function that is input.
As shown in FIG. 7, the following are known in a case in which the
fiber orientation is to be specified by angle components .theta.,
.phi. in the local coordinate system: the fiber orientation in the
human heart is .theta.=-90.degree. at the endocardium; the angle of
the fiber orientation increases at shorter distances from the
epicardium; the angle of the fiber orientation is
.theta.=+60.degree. at the epicardium; and .phi. is always
0.degree.. This hypothesis is expressed by the following
function
.theta.=-.pi./2+5.pi.r/6
.phi.=0
(-.pi..ltoreq..theta.,.phi..ltoreq..pi.),
where r (0.ltoreq.r.ltoreq.1) is the coordinate of the corrected
depth orientation.
[0071] The function thus input is then output to the projecting
section 13. The projecting section 13 projects the fiber
orientation expressed by the function onto the heart model (step
S104). Specifically, the projecting section 13 performs the
following operations. First, the projecting section 13 calculates
.theta. and .phi. of an electric potential coordinate. Then, the
projecting section 13 calculates, on the basis of the electric
potential distributions 51, 52 stored into the storage section 16
in steps S1021, S1023, a modeling coordinate corresponding to the
electric potential coordinate. The modeling coordinate is a target
of projection on the heart model. Thereafter, components of the
fiber orientation in the local coordinate system, which components
are calculated as the angle components .theta. and .phi., are
converted into components in the modeling coordinate system by use
of the orientation data 53, 54, 55 stored in the storage section 16
in steps S1022, S1025, S1026. Consequently, the fiber orientation
in the electric potential coordinate is projected onto the heart
model. The foregoing operations are repeated for a necessary number
of times so that the fiber placement is reproduced on the heart
model. The information on the heart model on which the fiber
placement is reproduced is output to the geometry section 14.
[0072] The geometry section 14 performs the geometry process on the
heart model on which the fiber placement is reproduced (step S105).
Specifically, the geometry section 14 converts the coordinate
system expressing the heart model from the modeling coordinate
system to a visual coordinate system based on the viewpoint. The
modeling coordinate system is a three-dimensional space. Conversion
of the modeling coordinate system into the visual coordinate system
that is two-dimensional plane makes it possible to represent the
heart model on a plane. The coordinate data of the heart model,
which coordinate data is converted into the visual coordinate
system in the foregoing manner, is output to the display section
15. When receiving the coordinate data, the display section 15
displays, on the screen, the heart model on which the fiber
placement is reproduced (step S106).
[0073] In the present embodiment, the fiber orientation of the
cardiac muscle cell is projected. It is also possible to project a
sheet orientation in the same manner.
Example 1
[0074] A heart model to which the hypothesis is applied is shown in
FIGS. 8(a) to 8(e) as an Example of the modeling device of
Embodiment 1. FIGS. 8(a) to 8(e) indicate the fiber orientations at
spots where the apex--base electric potential is 0V, 0.25V, 0.5V,
0.75V, and 1V, respectively. The figures show how the fiber
orientation changes continuously from the endocardium toward the
epicardium, changing from -90.degree. to +60.degree.. Further, the
respective fiber orientations fit in the shape of the heart.
Embodiment 2
[0075] The following describes another embodiment of the present
invention, with reference to FIGS. 9 and 10. In the present
embodiment, a modeling device that projects fiber orientations of
an animal heart onto a human heart model is described as an
example. Components having equivalent functions as those of
Embodiment 1 described above are given the same reference numerals,
and description thereof is omitted.
[0076] FIG. 9 is a functional block diagram of a modeling device 2
of the present embodiment. The modeling device 2 includes an input
section 20 (first input section, second input section, third input
section) in place of an input section 10 of a modeling device 1 of
Embodiment 1. Further, the modeling device 2 includes a storage
section 26 in place of a storage section 16 of the modeling device
1 of Embodiment 1. Furthermore, the modeling device 2 includes a
converting section (converting means) 27.
[0077] Shape information on a human heart (first object), shape
information on an animal heart (second object), and fiber
orientation information (characteristic information) on the animal
heart are fed into the input section 20. Information same as the
shape information on the human heart can be employed as the shape
information on the animal heart. Further, fiber orientation
information (hereinafter, "fiber orientation data") on the animal
heart contains a combination of spot data to specify a spot on the
animal heart and components of a vector indicating a fiber
orientation at the spot. The spot data and the components of the
vector are both defined in the modeling coordinate system.
[0078] The storage section 26 stores the following data on human:
coordinate data of the heart model reconstructed by the
reconstructing section 11; and data of the electric potential and
the electric current orientation at respective spots in the heart
model, which electric potential and the electric current
orientation are calculated by the virtually electrifying section
12. The storage section 26 also stores the following data on
animal: coordinate data of the heart model reconstructed by the
reconstructing section 11; and data of the electric potential and
the electric current orientation at respective spots in the heart
model, which electric potential and the electric current
orientation are calculated by the virtually electrifying section
12. Concretely, the storage section 26 stores the following data on
a human heart: polygon coordinate data 50; an apex--base electric
potential distribution 51; an endocardium--epicardium electric
potential distribution 52; longitude orientation data 53; latitude
orientation data 54; and corrected depth data 55. Further, the
storage section 26 stores the following data on an animal heart:
polygon coordinate data 60; an apex--base electric potential
distribution 61; an endocardium--epicardium electric potential
distribution 62; longitude orientation data 63; latitude
orientation data 64; and corrected depth data 65. The storage
section 26 is constituted of various memories such as RAM (Random
Access Memory).
[0079] The converting section 27 converts a characteristic (fiber
orientation) contained in the characteristic information input to
the input section 20 into orientation data based on a local
coordinate system of the second object (animal heart).
Specifically, the converting section 27 converts fiber orientation
information supplied via the input section 20 and defined in a
modeling coordinate system so that the fiber orientation
information is defined in a local coordinate system. Ways of
conversion will be described in detail later. The converting
section 27 may be constituted solely of hardware such as dedicated
IC, or may be constituted of a combination of hardware and software
such as a combination of a CPU, memory, and a program.
[0080] The following describes operation of the modeling device 2
of the present embodiment. FIG. 10 is a flowchart showing a process
sequence of the modeling device 2. The processes same as those of
Embodiment 1 described above are given the same reference numerals,
and detailed description thereof is omitted.
[0081] First, the shape information on the human heart and the
shape information on the animal heart are input into the input
section 20 of the modeling device 2. The modeling device 2 carries
out the processes of S101 and S102 with the use of the shape
information (step S200) on the human heart. As a result, the
following data on the human heart model are stored in the storage
section 16: the polygon coordinate data 50; the electric potential
distributions 51, 52; and the orientation data 53, 54, 55 on the
local coordinate system.
[0082] Then, the processes of S101 and S102 are carried out on the
animal heart in the same manner (step S201). As a result, the
following data on the animal heart model are stored in the storage
section 16: the polygon coordinate data 60; the electric potential
distributions 61, 62; and the orientation data 63, 64, 65 on the
local coordinate system.
[0083] Thereafter, the modeling device 2 requests an input of the
fiber orientation data obtained from the animal heart. The fiber
orientation data is input into the input section 10 as the
characteristic information (step S202).
[0084] The fiber orientation data thus input is fed into the
converting section 27. The converting section 27 converts this
fiber orientation data defined in the modeling coordinate system so
that the fiber orientation data is defined in the local coordinate
system (step S203). The following concretely describes this
conversion. The fiber orientation information is constituted of:
spot data identifying a spot on the animal heart model; and the
fiber orientation data of the spot. The spot data and the
orientation data are both defined in the modeling coordinate
system. The converting section 27 first refers to the orientation
data 63, 64, 65 of the local coordinate system that are stored in
the storage section 16, and calculates the local coordinate system
at the spot specified by the spot data. Then, the converting
section 27 converts the fiber orientation data defined in the
modeling coordinate system into fiber orientation data defined in
the local coordinate system by use of the vector components.
Examples of the fiber orientation data in the local coordinate
system are .theta. and .phi. in Embodiment 1. Consequently, the
fiber orientation defined in the modeling coordinate system is
converted into .theta. and .phi. in the local coordinate system.
The fiber orientation data converted to the local coordinate system
is input into the projecting section 13.
[0085] The projecting section 13 projects the animal fiber
orientation data converted to the local coordinate system onto the
human heart model (step S204). At this time, a correspondence
between a spot in the animal heart model and a spot in the human
heart model is established with the use of the electric potential
coordinate. Specifically, the projecting section 13 projects the
fiber orientation data at a spot in the animal heart model onto a
spot in the human heart model, which spot in the human heart model
has a same electric potential coordinate as the spot in the animal
heart model. Further, the projecting section 13 converts, with the
use of the orientation data 53, 54, 55 of the human local
coordinate system, the fiber orientation data converted to the
local coordinate system into the fiber orientation data defined in
the modeling coordinate system. The projecting section 13 projects
the fiber orientation data defined in the modeling coordinate
system onto the human heart model.
[0086] The information on the heart model on which the fiber
placement is reproduced by the projecting section 13 is supplied to
the geometry section 14, and the geometry section 14 performs the
geometry process (step S105). Then, the display section 15
displays, on the screen, the heart model on which the fiber
placement is reproduced (step S106).
[0087] With the modeling device of the present embodiment, the
correspondence is easily established between the spots on two heart
models by use of the electric potential coordinate, even if the
shapes of the hearts differ. Further, the fiber orientation data
input is first converted into the local coordinate system and then
projected onto the human heart model. This allows the fiber
orientation to be suitably projected onto the heart models of
various shapes.
[0088] The sections and the steps in the processes may be realized
by the following arrangement. Calculation means, such as CPU,
executes a program stored in storage means, such as ROM (Read Only
Memory) and RAM, to control input means such as a keyboard, output
means such as a display, and communication means such as an
interface circuit. Accordingly, a computer having these means
simply reads out the recording medium storing the program and
executes the program to realize the functions and processes of the
modeling device of the present embodiment. Further, storing the
program in a removable recording medium allows the functions and
the processes to be realized on any computer.
[0089] The recording medium may be a program media that is a memory
(not illustrated), such as ROM, to perform the processes in a
microcomputer. Alternatively, the recording medium may be a program
media readable by inserting the recording medium into a program
reading apparatus provided, although not illustrated, as an
external storage apparatus.
[0090] In any of the cases, it is preferable that the program
stored be accessed by the microprocessor to be executed. Further,
it is preferable that the program be read out, the program thus
read out be downloaded to a program storage area of a microcomputer
and executed. The program to be downloaded is stored in advance in
the main apparatus.
[0091] The program media is a recording medium that is removable
from a main device and permanently holds programs. Examples of the
program media include: tapes such as a magnetic tape and a cassette
tape; disks such as a magnetic disk (e.g. flexible disk, hard disk)
and CD/MO/MD/DVD; cards such as an IC card (including memory card);
and semiconductor memories such as a mask ROM, an EPROM (Erasable
Programmable Read Only Memory), an EEPROM (Electrically Erasable
Programmable Read Only Memory), and a flash ROM.
[0092] Further, if the system allows a connection to a
communication network, including the Internet, it is preferable
that the recording medium temporarily hold the program by
downloading the program from the communication network.
[0093] Further, if the program is to be downloaded from the
communication network, it is preferable that the program to be
downloaded be stored in advance in the main apparatus, or that the
program be installed from another recording medium.
[0094] As the foregoing describes, the modeling device of the
present invention includes: a first input section to which the
shape information of the object is input; a second input section to
which the characteristic information is input, which characteristic
information contains the correspondence between the spot in the
object and the characteristic; electrifying means for obtaining the
electric potential at a spot in the object at the time when the
predetermined voltage is applied to the object; and projecting
means for projecting, onto the spot in the object model, the
characteristic contained in the characteristic information that is
input to the second input section, the spot being contained in the
characteristic information, and the object model being based on the
shape information that is input to the first input section. The
projecting means specifies, on the basis of the electric potential
obtained by the electrifying means, a spot that is a target of
projection.
[0095] The characteristic information that is input to the second
input section contains a correspondence between the spot in the
object and the characteristic. The projecting means projects the
characteristic information onto the object model that is input to
the first input section. Thus, the characteristic corresponding to
the spot is projected onto the object model. The "spot" may be
either of a point and an area.
[0096] A spot in the object is specified on the basis of the
electric potential obtained by the electrifying means. The
electrifying means applies the predetermined voltage. Therefore,
the electric potential at a spot in the object is in the range of
0V to the predetermined voltage. Accordingly, a spot in the object
is specified in the range of 0V to the predetermined voltage. This
makes it possible to specify the spot in various objects having
different shapes by use of a common scale (not smaller than 0V and
not greater than the predetermined voltage). Accordingly, for
example a function with a variable of a coordinate based on the
electric potential is input to the second input section as the
characteristic information, the characteristic is easily projected
regardless of shape of a target object. In other words, with the
modeling device of the present invention, the characteristic is
projected onto various objects having different shapes. Further, no
geometric calculation is necessary to specify the spot, so that the
characteristic is easily projected onto an object even if the
object has a complex shape.
[0097] Further, it is preferable in the modeling device of the
present invention that: the characteristic contained in the
characteristic information be an orientation-related
characteristic; the electrifying means obtain the electric current
orientation at a spot in the object at a time when the voltage is
applied to the object; and the projecting means project the
orientation-related characteristic on the basis of the electric
current orientation obtained by the electrifying means.
[0098] The orientation in which the electric current flows depends
on the outer shape of the object. Hence, the electric current
orientation can be utilized as the local coordinate system. The
projecting means projects the orientation-related characteristic by
use of the local coordinate system based on the electric current
orientation. This makes it possible to project the
orientation-related characteristic in such a way as to fit in the
outer shape of the target object. Accordingly, with the modeling
device of the present invention, the orientation-related
characteristic related to the outer shape of the object is easily
projected onto various objects of different shape.
[0099] Further, it is preferable in the modeling device of the
present invention that: the electrifying means be virtually
electrifying means for virtually applying the voltage to the object
model based on the shape information that is input to the first
input section, and obtaining the electric potential and/or the
electric current orientation by calculation.
[0100] With this configuration, the electric potential and/or the
electric current orientation at any spot in the object are
obtained, even if a voltage cannot be actually applied to the
object, such as a human heart.
[0101] Further, another modeling device of the present invention
includes: a first input section to which the shape information of
the first object is input; a second input section to which the
characteristic information is input, which characteristic
information contains a correspondence between the spot in the
second object and the characteristic; electrifying means for
obtaining the electric potential at a spot in the first object at a
time when the predetermined voltage is applied to the first object
and the electric potential at a spot in the second object at a time
when the predetermined voltage is applied to the second object; and
projecting means for (i) specifying, on the basis of the electric
potential obtained by the electrifying means, a first spot in the
first object model based on the shape information that is input to
the first input section, which first spot corresponds to a second
spot in the second object, which second spot is contained in the
characteristic information that is input to the second input
section, and (ii) projecting the characteristic onto the spot.
[0102] With this configuration, the electrifying means applies the
voltage to obtain the electric potential at a spot in the first
object. In the same manner, the electrifying means obtains the
electric potential at a spot in the second object. Then, the
projecting means establishes a correspondence between the spot in
the second object and the spot in the first object model on the
basis of the electric potential at the spot in the second object.
For example, the projecting means establishes a correspondence
between the spot in the second object and the spot, having a same
electric potential as that of the spot in the second object, in the
first object model. Thereafter, the projecting means projects the
characteristic information on the spot in the second object, which
characteristic information is input to the second input section,
onto the corresponding spot in the first object model. By the
foregoing way, the characteristic information on a spot in the
second object is projected onto the corresponding spot in the first
object.
[0103] The projecting means establishes the correspondence between
the spot in the first object and the spot in the second object on
the basis of the electric potential obtained by the electrifying
means. The electrifying means applies the predetermined voltage.
Therefore, the electric potential at a spot in the objects is in
the range of 0V to the predetermined voltage. Accordingly, a spot
in each of the objects is specified in the range of 0V to the
predetermined voltage. This makes it possible to easily establish a
correspondence by use of a common scale (not smaller than 0V and
not greater than the predetermined voltage) even if the shape of
the first object and the shape of the second object are complex and
different. Accordingly, with the modeling device of the present
invention, a modeling device by which characteristic information
obtained from an object is easily projected onto a
differently-shaped object, even if the object, from which the
characteristic information is obtained, has a complex shape.
Further, no geometric calculation is necessary to establish a
correspondence between spots, so that the characteristic is easily
projected even if the object has a complex shape.
[0104] Further, it is preferable in the modeling device of the
present invention that: the characteristic contained in the
characteristic information relate to an orientation; and the
electrifying means obtains, on the basis of the electric current
orientation at a spot in the object at a time when the voltage is
applied to the first object and at a time when the voltage is
applied to the second object, the local coordinate system of the
first object and the local coordinate system of the second object.
Further, it is preferable that: the modeling device of the present
invention further include converting means for converting the
orientation-related characteristic contained in the characteristic
information that is input to the second input section, into
orientation data in the local coordinate system of the second
object; and the projecting means project, on the basis of the local
coordinate system of the first object, the orientation data
converted by the converting means.
[0105] The orientation in which the electric current flows depends
on the outer shape of the object. Hence, the electric current
orientation can be utilized as the local coordinate system. The
converting means converts the orientation-related characteristic
input into an expression based on the local coordinate system. The
projecting means projects the orientation-related characteristic
expressed on the basis of the local coordinate system, so that
orientation-related characteristic is projected in such a way as to
fit in the outer shape of the target. This makes it possible to
project the orientation-related characteristic onto the first
object in such a way as to fit in the outer shape of the first
object, even if the outer shape of the first object is different
from that of the second object. Accordingly, with the modeling
device of the present invention, the orientation-related
characteristic related to the shape of the object is easily
projected from an object onto another object.
[0106] Further, it is preferable that; the modeling device of the
present invention further include a third input section to which
the shape information of the second object is input; the
electrifying means be virtually electrifying means for virtually
applying the voltage to the object model based on the shape
information that is input to the first input section and the object
model based on the shape information that is input to the third
input section, and obtaining the electric potential and/or the
electric current orientation by calculation.
[0107] With this configuration, the electric potential and/or the
electric current orientation at any spot in the object are
obtained, even if a voltage cannot be actually applied to the
object, such as a human heart.
[0108] Further, in the modeling device of the present invention,
the object may be a heart, and the characteristic contained in the
characteristic information that is input to the second input
section may relate to the fiber orientation or the sheet
orientation of a cardiac muscle cell.
[0109] With this configuration, the information on the fiber
orientation or the sheet orientation of the cardiac muscle cell
obtained from a heart is projected onto a target heart model. This
makes it possible to realize a modeling device by which the
information on the fiber orientation and the sheet orientation is
projected onto a target heart model on the basis of findings of the
fiber orientation or the sheet orientation from another heart,
thereby contributing to medical treatment and diagnosis.
[0110] Further, it is preferable in the modeling device of the
present invention that: the electrifying means obtain an electric
potential at a spot in the heart at a time when the predetermined
voltage is applied between the apex and the base and an electric
potential at a spot in the heart at a time when the predetermined
voltage is applied between the endocardium and the epicardium; the
projecting means project the orientation-related characteristic as
the characteristic information on the basis of (i) the electric
potential at the time when the predetermined voltage is applied
between the apex and the base, (ii) the electric potential at the
time when the voltage is applied between the endocardium and the
epicardium, and (iii) an angle along a rotation orientation having
a central axis extending in an orientation between the apex and the
base.
[0111] With this configuration, the spot in an orientation
substantially corresponding to a height orientation of the heart is
specified by the electric potential in the orientation between the
apex and the base. Further, the spot in an orientation
substantially corresponding to the depth orientation of the heart
is specified by the electric potential in the orientation between
the endocardium and the epicardium. Further, the spot in the
rotation orientation is specified by the angle along the rotation
orientation having the central axis extending in the orientation
between the apex and the base. A coordinate system expressed by
these three coordinates is similar to a cylindrical coordinate
system or a spherical coordinate system, and can define any point
in a three-dimensional space. Further, the coordinates of the
coordinate system fit in the characteristic of the shape of the
heart (i.e. a hollow spherical complex shape in which only an angle
in a vertical orientation and an angle in the rotation orientation
are easily identifiable), and therefore are suitable to specify a
spot in the heart. Thus, a general specification of spots can be
performed in a manner independent from differences in shape between
species or individuals.
[0112] Further, it is preferable in the modeling device of the
present invention that: the local coordinate system be an
orthogonal coordinate system; a first coordinate axis of the local
coordinate system extend in the electric current orientation at the
time when the voltage is applied between the apex and the base; a
second coordinate axis of the local coordinate system be orthogonal
to the first coordinate axis and an axis extending in the electric
current orientation at the time when the voltage is applied between
the endocardium and the epicardium; and a third coordinate axis of
the local coordinate system be orthogonal to the first coordinate
axis and to the second coordinate axis.
[0113] When the voltage is applied between the apex and the base,
the electric current orientation (i.e. orientation in which the
first coordinate axis extends) is along a cardiac wall. Further,
when the voltage is applied between the endocardium and the
epicardium, the electric current orientation is substantially
vertical to the cardiac wall. The second axis is vertical to the
electric current and therefore is substantially along the cardiac
wall. Further, the third axis is orthogonal to both of the first
axis and the second axis and therefore is substantially vertical to
the cardiac wall. Accordingly, the respective coordinates of the
local coordinate system are related to the outer shape of the
heart. This makes it possible to project information on the fiber
orientation and the sheet orientation, both of which are related to
the outer shape of the heart, in such a way as to fit in the shape
of the target heart without contradiction.
[0114] Further, it is preferable that the modeling device of the
present invention further include: geometry means for performing
the geometry process on the object on which the characteristic is
projected by the projecting means; and a display section to display
the object on which the geometry process is performed by the
geometry means.
[0115] With this configuration, the target object on which the
characteristic information is projected is visually confirmed on
the display section.
[0116] Respective means of the modeling device may be realized by
hardware, or may be realized by causing a computer to execute a
program. Concretely, a program of the present invention is to cause
a computer to operate as any of the respective means of the
modeling device. Further, a recording medium of the present
invention stores the program.
[0117] If the program is executed by the computer, the computer
operates as the respective means of the modeling device.
Accordingly, a modeling device is realized by which characteristic
information obtained from an object is easily projected onto a
differently-shaped object, even if the object, from which the
characteristic information is obtained, has a complex shape.
[0118] Further, a method of establishing a correspondence between a
spot in a first object and a spot in a second object according to
the present invention includes: obtaining an electric potential
distribution at a time when the predetermined voltage is applied to
the first object and an electric potential distribution at a time
when the predetermined voltage is applied to the second object; and
establishing, on the basis of the electric potential distribution
thus obtained, a correspondence between the spot in the first
object and the spot in the second object.
[0119] With this arrangement, the correspondence between the points
or areas in the objects is established on the basis of the electric
potential distribution. The electric potential distribution is a
distribution at a time when the predetermined voltage is applied.
Therefore, any spot in the objects is in the range of 0V to the
predetermined voltage. Accordingly, any spot in the objects is
specified in the range of 0V to the predetermined voltage. The
foregoing arrangement makes it possible to establish a
correspondence between the points or areas by use of a common scale
(not smaller than 0V and not greater than predetermined voltage),
even if the shapes of the first object and the second object are
different.
[0120] The present invention is not limited to the description of
the embodiments above, but may be altered by a skilled person
within the scope of the claims. An embodiment based on a proper
combination of technical means disclosed in different embodiments
is encompassed in the technical scope of the present invention.
INDUSTRIAL APPLICABILITY
[0121] A modeling device of the present invention easily projects
characteristic information obtained from an object onto a
differently-shaped object, even if the object, from which the
characteristic information is obtained, has a complex shape.
Therefore, for example on the basis of findings obtained from an
animal heart, a fiber orientation is projected onto a human heart
to create a human heart model. The heart model may be utilized in
medical care to give an explanation to a patient. Further, a
simulation device to simulate heart beats is realized by applying
the modeling device to the simulation device.
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