U.S. patent application number 12/871634 was filed with the patent office on 2010-12-23 for image diagnosis apparatus and image diagnosis method.
This patent application is currently assigned to CANON KABUSHIKI KAISHA. Invention is credited to Takaaki Endo, Kiyohide Satoh, Koichiro Wanda.
Application Number | 20100324422 12/871634 |
Document ID | / |
Family ID | 43031875 |
Filed Date | 2010-12-23 |
United States Patent
Application |
20100324422 |
Kind Code |
A1 |
Wanda; Koichiro ; et
al. |
December 23, 2010 |
IMAGE DIAGNOSIS APPARATUS AND IMAGE DIAGNOSIS METHOD
Abstract
This invention provides a technique to dynamically set an
imaging parameter appropriate for observing a region of interest on
an object to generate a high-quality echogram while maintaining the
operability to change the position and orientation of a probe. A
region-of-interest acquisition unit (1010) acquires region
information that defines the region of interest. A position and
orientation acquisition unit (1020) acquires position and
orientation information representing the position and orientation
of a probe. A parameter deciding unit (1022) obtains an imaging
parameter based on the positional relationship between an imaging
range decided based on the position and orientation information and
the region of interest defined by the region information, and
outputs the obtained imaging parameter to an imaging unit
(1100).
Inventors: |
Wanda; Koichiro;
(Yokohama-shi, JP) ; Endo; Takaaki; (Urayasu-shi,
JP) ; Satoh; Kiyohide; (Kawasaki-shi, JP) |
Correspondence
Address: |
CANON U.S.A. INC. INTELLECTUAL PROPERTY DIVISION
15975 ALTON PARKWAY
IRVINE
CA
92618-3731
US
|
Assignee: |
CANON KABUSHIKI KAISHA
Tokyo
JP
|
Family ID: |
43031875 |
Appl. No.: |
12/871634 |
Filed: |
August 30, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
PCT/JP2010/000606 |
Feb 2, 2010 |
|
|
|
12871634 |
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Current U.S.
Class: |
600/443 |
Current CPC
Class: |
A61B 8/42 20130101; A61B
8/4245 20130101; A61B 8/54 20130101; A61B 8/5238 20130101; A61B
8/00 20130101; A61B 5/055 20130101 |
Class at
Publication: |
600/443 |
International
Class: |
A61B 8/14 20060101
A61B008/14 |
Foreign Application Data
Date |
Code |
Application Number |
May 1, 2009 |
JP |
2009-112294 |
Claims
1. An image diagnosis apparatus connected to an imaging apparatus
for obtaining an image of an object, comprising: a first
acquisition unit that acquires region information that defines a
region of interest on the object; a second acquisition unit that
acquires position and orientation information representing a
position and orientation of a probe provided in the imaging
apparatus; a calculation unit that obtains an imaging parameter of
the imaging apparatus based on a positional relationship between an
imaging range of the imaging apparatus decided based on the
position and orientation information and the region of interest
defined by the region information; and an output unit that outputs
the imaging parameter.
2. The image diagnosis apparatus according to claim 1, wherein said
first acquisition unit acquires the region information that defines
the region of interest on a reference coordinate system, and said
second acquisition unit acquires the position and orientation
information representing the position and orientation of the probe
on the reference coordinate system.
3. The image diagnosis apparatus according to claim 1, wherein said
calculation unit comprises: a first unit that obtains an
intersection region between the imaging range and the region of
interest defined by the region information using the region
information and the position and orientation information; and a
second unit that obtains the imaging parameter based on the
intersection region.
4. The image diagnosis apparatus according to claim 3, wherein said
first unit obtains, as the intersection region, a cross section, in
the imaging range, of the region of interest defined by the region
information.
5. The image diagnosis apparatus according to claim 3, wherein the
imaging parameter is a focus position, and said second unit obtains
a neighborhood of the intersection region as the focus
position.
6. The image diagnosis apparatus according to claim 3, wherein the
imaging parameter is a focus position, and said second unit obtains
one of an interior and a boundary of the intersection region as the
focus position.
7. The image diagnosis apparatus according to claim 1, wherein the
imaging parameter is a focus position, and said calculation unit
obtains, as the focus position, a position of one point closest to
the region of interest represented by the region information within
the imaging range.
8. The image diagnosis apparatus according to claim 1, wherein said
output unit outputs the imaging parameter to the imaging apparatus
so as to set the imaging parameter in the imaging apparatus.
9. The image diagnosis apparatus according to claim 1, further
comprising an unit that acquires an echogram obtained by the
imaging apparatus in which the imaging parameter output from said
output unit has been set, and generates a three-dimensional
echogram using the acquired echogram.
10. The image diagnosis apparatus according to claim 1, wherein
said first acquisition unit acquires the region information for a
region designated on a slice selected from a plurality of
tomograms.
11. An image diagnosis method performed by an image diagnosis
apparatus connected to an imaging apparatus for obtaining an image
of an object, comprising: a first acquisition step of acquiring
region information that defines a region of interest on the object;
a second acquisition step of acquiring position and orientation
information representing a position and orientation of a probe
provided in the imaging apparatus; a calculation step of obtaining
an imaging parameter of the imaging apparatus based on a positional
relationship between an imaging range of the imaging apparatus
decided based on the position and orientation information and the
region of interest defined by the region information; and an output
step of outputting the imaging parameter.
12. (canceled)
13. A computer-readable storage medium storing a computer program
which causes a computer to function as the image diagnosis
apparatus of claim 1.
Description
TECHNICAL FIELD
[0001] The present invention relates to an image diagnosis
technique (modality) such as ultrasonic diagnosis.
BACKGROUND ART
[0002] An ultrasonic diagnosis apparatus transmits/receives
ultrasonic waves to/from an object via an ultrasonic probe,
generates tomograms and the like based on received signals, in
other words, reflective echo signals including reflected waves and
the like from the inside of the object, and provides information
useful for diagnosis. The ultrasonic probe is generally formed by
arranging a plurality of oscillators on a line, curve, or plane at
equal intervals. A plurality of selected oscillators simultaneously
oscillate to form an ultrasonic beam. The beam scans a part to be
diagnosed in an object. Based on a reflective echo signal including
a reflected wave of the beam or the like, an echogram which
visualizes a slice of the object is generated.
[0003] To generate a high-quality echogram suitable for diagnosis
in the medical field where the image diagnosis apparatus is used,
various kinds of imaging parameters used to control the ultrasonic
diagnosis apparatus need to be appropriately set in accordance with
the observation target. An imaging parameter of the ultrasonic
diagnosis apparatus is "STC (Sensitive Time Control)" which changes
the gain of the amplifier of the receiving device in accordance
with the reflective echo return time. "Depth" which controls the
imaging range in the depth direction and "ultrasonic beam focus
position" which controls focus processing are also known as
adjustable imaging parameters. Sound pressure to be applied to an
observation target is also adjusted.
[0004] As a focus processing method, for example, electronic
focusing is known, which delays ultrasonic waves emitted from the
simultaneously driven oscillators to make the wavefronts of the
ultrasonic waves emitted from the oscillators match at an arbitrary
focal point. The focus processing also includes a process to
calculate the delay time of each received reflected wave and
selectively receiving waves. For a linear probe, a depth position
in the scanning line direction is the focus position.
[0005] In general, a doctor or technician interactively adjusts the
imaging parameters using dials and levers provided on the console
of the apparatus while visually confirming obtained images
displayed on a monitor. However, several attempts to facilitate
imaging parameter setting have also been reported.
[0006] For example, patent reference 1 discloses a method of
designating a position of interest on an echogram acquired by
ultrasonic beam transmission/reception, and performing focus
processing for each scanning line to obtain a focus at the position
of interest. Patent reference 2 discloses a method of designating a
ROI (region of interest) on an echogram acquired by ultrasonic beam
transmission/reception, and limiting the range to be scanned by an
ultrasonic beam.
[0007] On the other hand, a technique is known which integrates
two-dimensional echograms obtained freehand to generate a
three-dimensional echogram (volume data) (three-dimensional
reconstruction), and then generates an arbitrary cross section
based on that volume data, thereby displaying an echogram more
suitable for diagnosis (non-patent reference 1). According to this
technique, for example, the same object is imaged using another
image diagnosis apparatus (modality) such as an MRI to generate an
echogram corresponding to a cross section of interest, and the
obtained images are displayed side by side. This makes it possible
to easily do diagnosis using a plurality of modalities. For
example, patent reference 3 discloses a technique of detecting the
position or movement of a probe and displaying the probe locus
based on it, thereby indicating the presence/absence of an
unscanned region.
Citation List
PATENT REFERENCES
[0008] Patent Reference 1: Japanese Patent Laid-Open No.
2003-93389
[0009] Patent Reference 2: Japanese Patent Laid-Open No.
2008-99729
[0010] Patent Reference 3: Japanese Patent Laid-Open No.
2008-86742
NON-PATENT REFERENCES
[0011] Non-patent Reference 1: O. V. Solberg, F. Lindseth, H. Torp,
R. E. Blake, and T. A. N. Hernes, "Freehand 3D ultrasound
reconstruction algorithms--a review," Ultrasound in Medicine &
Biology, vol. 33, no. 7, pp. 991-1009, July 2007.
SUMMARY OF INVENTION
Technical Problem
[0012] However, the conventional techniques can only designate a
region of interest on an image. It is therefore impossible to
appropriately apply the imaging parameters to a region outside the
imaging range of the probe. In addition, the imaging parameters
cannot appropriately be changed immediately following the position
and orientation of the probe. When the probe has changed its
position and orientation, the region of interest needs to be
designated each time. Alternatively, the position and orientation
of the probe must be fixed. That is, the use conditions are
limited.
[0013] For example, when an object part (for example, cancerous
tumor or specific organ) to be observed by a doctor with special
interest is projected in a B-mode image, it is impossible to
acquire an image always having a focus set on the part of interest
while maintaining the operability to change the position and
orientation of the probe.
[0014] The present invention has been made in consideration of the
above-described problems, and has as its object to provide a
technique to dynamically set an imaging parameter appropriate for
observation of a region of interest on an object to generate a
high-quality echogram while maintaining the operability to change
the position and orientation of a probe.
[0015] Assume that the same object is imaged using another image
diagnosis apparatus such as an MRI, and the image of the cross
section of interest is compared with an echogram. In this case, to
obtain the echogram corresponding to the cross section of interest,
reconstruction of the three-dimensional echogram (volume data) of
the entire target object is necessary. However, it is difficult to
confirm whether the three-dimensional echogram necessary for
generating the image of the cross section of interest has been
generated.
[0016] To solve this problem, the technique disclosed in patent
reference 3 implements a function of allowing to confirm whether
the three-dimensional echogram of an entire target object has been
acquired. However, it is impossible to determine whether imaging
necessary for obtaining a specific cross section or part of
interest to be observed by a doctor has been performed. For this
reason, when generating a desired cross-sectional image or
generating an image including a region of interest on a
cross-sectional image, the image diagnosis apparatus needs
redundant imaging processing and image processing, and the operator
needs a redundant probe operation. It is therefore another object
of the present invention to provide a technique of efficiently
acquiring an image corresponding to a cross section or position of
interest of another modality such as an MRI.
Solution to Problem
[0017] According to the present invention, there is provided an
image diagnosis apparatus connected to an imaging apparatus for
obtaining an image of an object, characterized by comprising first
acquisition means for acquiring region information that defines a
region of interest on the object, second acquisition means for
acquiring position and orientation information representing a
position and orientation of a probe provided in the imaging
apparatus, calculation means for obtaining an imaging parameter of
the imaging apparatus based on a positional relationship between an
imaging range of the imaging apparatus decided based on the
position and orientation information and the region of interest
defined by the region information, and output means for outputting
the imaging parameter.
Advantageous Effects of Invention
[0018] According to the arrangement of the present invention, it is
possible to dynamically set an imaging parameter appropriate for
observation of a region of interest on an object to generate a
high-quality echogram while maintaining the operability to change
the position and orientation of a probe. In addition, it is
possible to efficiently acquire an image corresponding to a cross
section or position of interest of another modality such as an
MRI.
[0019] Further features of the present invention will become
apparent from the following description of exemplary embodiments
with reference to the attached drawings. Note that the same
reference numerals denote the same or similar parts throughout the
drawings.
BRIEF DESCRIPTION OF DRAWINGS
[0020] The accompanying drawings, which are incorporated in and
constitute a part of the specification, illustrate embodiments of
the invention and, together with the description, serve to explain
the principles of the invention.
[0021] FIG. 1 is a block diagram showing an example of the
functional arrangement of an ultrasonic diagnosis apparatus
according to the first embodiment;
[0022] FIG. 2 is a block diagram showing an example of the hardware
configuration of a computer applicable to an information processing
unit 1000 or 7100;
[0023] FIG. 3 is a flowchart of processing to be executed by a
region-of-interest acquisition unit 1010;
[0024] FIG. 4 is a flowchart of processing of generating a
three-dimensional echogram including a region of interest;
[0025] FIG. 5 is a view showing examples of a region of interest, a
probe imaging region, and an intersection region between them on a
reference coordinate system;
[0026] FIG. 6 is a schematic view showing the relationship between
a probe 601, an imaging region 602, and an intersection region 603
when viewed from a direction perpendicular to a plane serving as
the imaging region;
[0027] FIG. 7 is a block diagram showing an example of the
functional arrangement of an ultrasonic diagnosis apparatus
according to the second embodiment of the present invention;
[0028] FIG. 8 is a flowchart of processing of generating a
three-dimensional echogram including a target region;
[0029] FIG. 9 is a flowchart illustrating details of a process in
step S301;
[0030] FIG. 10 is a view for explaining processes in steps S801 and
S803;
[0031] FIG. 11 is a view for explaining processing of obtaining a
target region when a region of interest is a point;
[0032] FIG. 12 is a view showing the relationship between volume
data 1001, cross section 1002 of interest, morbid portion 1003, and
partial region 1004 of interest of an MRI;
[0033] FIG. 13 is a view showing a display example of the echogram
of the cross section of interest; and
[0034] FIG. 14 is a view showing a display example of the echogram
of the cross section of interest.
DESCRIPTION OF EMBODIMENTS
[0035] The embodiments of the present invention will now be
described with reference to the accompanying drawings. Note that
the embodiments to be explained below are examples of specifically
practicing the present invention, and detailed embodiments
described in the appended claims.
First Embodiment
[0036] An image diagnosis apparatus according to this embodiment is
an ultrasonic diagnosis apparatus which images a region of interest
by focus processing appropriate for imaging the region of interest
defined on a reference coordinate system, and generates a
three-dimensional echogram with a focus on the region of
interest.
[0037] <Arrangement of Ultrasonic Diagnosis Apparatus of
Embodiment>
[0038] FIG. 1 is a block diagram showing an example of the
functional arrangement of an ultrasonic diagnosis apparatus
according to this embodiment. As shown in FIG. 1, the ultrasonic
diagnosis apparatus according to this embodiment includes an
information processing unit 1000, imaging unit 1100, and position
and orientation measuring unit 1200.
[0039] The position and orientation measuring unit 1200 will be
described first. The position and orientation measuring unit 1200
measures the position and orientation of an ultrasonic probe (not
shown), which constitutes part of the imaging unit 1100, on a
reference coordinate system defined in the physical space. The
position and orientation measuring unit 1200 then transmits, to the
information processing unit 1000, position and orientation
information representing the measured position and orientation of
the probe. As the position and orientation measuring unit 1200, a
sensor of any type such as a magnetic sensor, mechanical sensor, or
optical sensor is usable. Note that in the following explanation,
the position and orientation measuring unit 1200 is assumed to be
calibrated in advance so that the position and orientation
information of the probe on the reference coordinate system can be
acquired.
[0040] The reference coordinate system is, for example, a
coordinate system whose origin is defined at one point in the
physical space where the ultrasonic diagnosis apparatus of this
embodiment is arranged (for example, an immobile point such as a
bed on which a patient lies), and whose X-, Y-, and Z-axes are
defined as three axes that cross at right angles at that origin.
However, the following embodiment may be practiced using an object
coordinate system (patient coordinate system) as the reference
coordinate system by regarding an object (patient) as a rigid body.
In this case, the position and orientation measuring unit 1200 also
measures the position and orientation of the object. The position
and orientation of the probe on the object coordinate system are
calculated from the relative position and orientation relationship
between the object and the probe. Note that the object coordinate
system is a coordinate system whose origin is defined at one point
on the object, and whose X-, Y-, and Z-axes are defined as three
axes that cross at right angles at that origin.
[0041] The imaging unit 1100 (imaging apparatus) will be described
next. The imaging unit 1100 obtains echograms of an object in
accordance with an imaging parameter supplied from the information
processing unit 1000. The echograms obtained by imaging are
transmitted to the information processing unit 1000. Note that in
this embodiment, the ultrasonic probe provided in the imaging unit
1100 is assumed to be of linear type, and an echogram imaged by the
imaging unit 1100 is assumed to be a two-dimensional B-mode image.
The imaging unit 1100 can have the same arrangement as that of a
general ultrasonic diagnosis apparatus except that the imaging
parameter can be controlled from the outside.
[0042] The information processing unit 1000 will be described next.
The information processing unit 1000 obtains an imaging parameter
appropriate for imaging a region of interest of an object,
transmits the obtained imaging parameter to the imaging unit 1100,
and sets it. In this embodiment, a focus position is used as the
imaging parameter. In addition, the information processing unit
1000 acquires echograms from the imaging unit 1100 in which the
imaging parameter is set, and integrates the acquired echograms,
thereby generating a three-dimensional echogram associated with the
region of interest.
[0043] As shown in FIG. 1, the information processing unit 1000
includes a region-of-interest acquisition unit 1010,
region-of-interest information storage unit 1011, position and
orientation acquisition unit 1020, intersection region calculation
unit 1021, parameter deciding unit 1022, echogram acquisition unit
1030, and image generation unit 1031.
[0044] The region-of-interest acquisition unit 1010 acquires region
information which defines a region of interest of an object in the
physical space (in the reference coordinate system) (first
acquisition). The region information can be of any type as far as
it can define a region of interest of an object in the physical
space. For example, information representing the three-dimensional
coordinate values of the central position of a region and the
radius of the region is usable. Alternatively, formula information
to be used to derive it may be used. In this embodiment, a region
of interest is assumed to be a sphere, and region information is
assumed to be information representing the three-dimensional
coordinate values of the center of the sphere and the radius of the
sphere. Note that the input form of region information to the
information processing unit 1000 is not particularly limited. The
region information may be received from an external apparatus via a
network, or input from a keyboard, mouse, or the like operated by
the user. The region-of-interest acquisition unit 1010 acquires
region information input in this way, and temporarily stores it in
the region-of-interest information storage unit 1011.
[0045] The position and orientation acquisition unit 1020 acquires,
from the position and orientation measuring unit 1200, position and
orientation information representing the position and orientation
of the probe of the imaging unit 1100 on the reference coordinate
system (second acquisition). The position and orientation
acquisition unit 1020 sends the acquired position and orientation
information to the intersection region calculation unit 1021 of the
succeeding stage.
[0046] The intersection region calculation unit 1021 performs the
following processing using the region information stored in the
region-of-interest information storage unit 1011 and the position
and orientation information sent from the position and orientation
acquisition unit 1020. More specifically, the intersection region
calculation unit 1021 obtains, as an intersection region, a cross
section of the region of interest defined by the region information
in the imaging range of the imaging unit 1100 which is decided
based on the position and orientation information. The intersection
region calculation unit 1021 sends information (intersection region
information) representing the thus obtained intersection region to
the parameter deciding unit 1022 of the succeeding stage. The
intersection region calculation unit 1021 also sends the region
information and position and orientation information to the image
generation unit 1031 of the succeeding stage.
[0047] The parameter deciding unit 1022 calculates an optimum
imaging parameter to be set in the imaging unit 1100 using the
intersection region information sent from the intersection region
calculation unit 1021. In this embodiment, the parameter deciding
unit 1022 calculates a focus position at which an in-focus state is
obtained in a region on the object corresponding to the
intersection region. The parameter deciding unit 1022 transmits the
calculated imaging parameter to the imaging unit 1100. The
parameter deciding unit 1022 also sends, to the image generation
unit 1031 of the succeeding stage, the obtained imaging parameter
and the intersection region information used to obtain the imaging
parameter.
[0048] The echogram acquisition unit 1030 acquires an echogram
obtained by the imaging unit 1100. Note that the acquired echogram
is associated with the imaging parameter obtained by the parameter
deciding unit 1022 and various kinds of information used to obtain
the imaging parameter. For example, the imaging parameter and
various kinds of information used by the parameter deciding unit
1022 are added with the same identifier. This identifier is also
added to the obtained echogram, thereby associating them. If an
imaging parameter is uniquely decided in correspondence with each
position and orientation of the probe, the position and orientation
information of the probe may be used as identification information.
Alternatively, various kinds of information used by the parameter
deciding unit 1022 may be transmitted to the imaging unit 1100
together with the imaging parameter, added to the echogram, and
then input to the echogram acquisition unit 1030 again.
[0049] The image generation unit 1031 integrates echograms acquired
by the echogram acquisition unit 1030 to generate a
three-dimensional echogram (volume data) including the region of
interest. The image generation unit 1031 outputs the generated
three-dimensional echogram. The output destination is not
particularly limited. The three-dimensional echogram may be
transmitted to an external apparatus via a network, or output to a
display apparatus for the purpose of display.
[0050] <Processing Procedure to Be Performed by Ultrasonic
Diagnosis Apparatus>
[0051] Processing to be performed by the ultrasonic diagnosis
apparatus according to the embodiment will be described next. FIG.
3 is a flowchart of processing to be executed by the
region-of-interest acquisition unit 1010. In step S301, the
region-of-interest acquisition unit 1010 acquires region
information that defines a region of interest of an object in the
physical space (in the reference coordinate system). In step S302,
the region-of-interest acquisition unit 1010 temporarily stores the
acquired region information in the region-of-interest information
storage unit 1011.
[0052] Processing of generating a three-dimensional echogram
including a region of interest will be described below with
reference to FIG. 4 which shows the flowchart of the processing.
Note that processing according to the flowchart of FIG. 4 is
executed after processing according to the flowchart of FIG. 3 has
ended. When the processing according to the flowchart of FIG. 4
starts, the ultrasonic diagnosis apparatus has already been
activated so as to be able to obtain an echogram, and the position
and orientation of the probe have also been measured.
[0053] In step S401, the position and orientation acquisition unit
1020 acquires the position and orientation information of the probe
from the position and orientation measuring unit 1200, and sends
the acquired position and orientation information to the
intersection region calculation unit 1021 of the succeeding stage.
In step S402, the intersection region calculation unit 1021
calculates information (imaging region information) representing
the imaging region (imaging range) of the probe on the reference
coordinate system using the position and orientation information of
the probe. The imaging region is information representing a region
in the physical space, which is captured in an image to be obtained
by the probe. The imaging region is defined by a plane (imaging
plane) in the physical space and a region on the plane. The imaging
plane is uniquely defined in the reference coordinate system based
on the position and orientation of the probe. On the other hand,
the region on the plane is calculated based on the number of
oscillators, the pitch between the oscillators, the depth in the
direction of echo signal transmission, and the like. Note that the
number of oscillators, the pitch between them, and the model of
beam forming are assumed to be known information.
[0054] In step S403, the intersection region calculation unit 1021
obtains a cross section of the region of interest in the imaging
region as an intersection region using the region information
stored in the region-of-interest information storage unit 1011 and
the imaging region information calculated in step S402. In this
embodiment, since the region of interest is expressed as a sphere,
the calculated intersection region is described by a circle (center
coordinates and radius) on an echogram. Note that the parameters of
a circle on a plane obtained by cutting a sphere in a space along
the plane can be derived using rudimentary geometry, and a detailed
description thereof will be omitted here.
[0055] FIG. 5 is a view showing examples of a region of interest, a
probe imaging region, and an intersection region between them on
the reference coordinate system. Referring to FIG. 5, reference
numeral 501 denotes a region of interest (sphere); 502, a probe;
503, an imaging region calculated based on the position and
orientation information of the probe; and 504, a circle
(intersection region) representing a cross section of the region
501 of interest in the imaging region 503. Note that a portion of
the region 501 of interest shown in FIG. 5 on the near side of the
intersection region 504 is not illustrated for the descriptive
convenience.
[0056] The intersection region calculation unit 1021 sends
information (intersection region information) of the thus obtained
intersection region to the parameter deciding unit 1022 of the
succeeding stage. The intersection region calculation unit 1021
also sends the region information and the position and orientation
information to the image generation unit 1031 of the succeeding
stage.
[0057] In step S404, the intersection region calculation unit 1021
determines whether the intersection region could be obtained in
step S403. Upon determining that the intersection region could not
be obtained, the process returns to step S401, and the processes in
steps S401 to S403 are repeated based on the position and
orientation information of the probe input at the next time. On the
other hand, if the intersection region could be obtained, the
process advances to step S405.
[0058] In step S405, the parameter deciding unit 1022 obtains an
imaging parameter based on the intersection region information.
FIG. 6 is a schematic view showing the relationship between a probe
601, an imaging region 602, and an intersection region 603 when
viewed from a direction perpendicular to a plane serving as the
imaging region. Referring to FIG. 6, the intersection region 603
can be recognized as a region on the plane representing the imaging
region 602.
[0059] Various methods are available to decide a focus position
605. In this embodiment, the user may select one of the methods, or
a predetermined deciding method may be used. For example, to set a
focus near the boundary of the intersection region 603, the
distance up to the intersection region 603 is decided as the focus
position 605 independently for each scanning line 604. To set a
focus inside the intersection region 603, an intermediate position
between the intersections (two points) of the scanning line 604 and
the intersection region 603 may be set as the focus position, as
indicated by 606. Alternatively, the distance up to the central
point of the intersection region 603 may be set as the focus
position common to all scanning lines. Any other deciding method
capable of setting a focus on the intersection region 603 is
usable. For example, a focus position deciding method disclosed in
patent reference 1 is also applicable.
[0060] In step S406, the parameter deciding unit 1022 sends the
obtained imaging parameter to the imaging unit 1100. This allows
the imaging unit 1100 to set, in itself, the imaging parameter
obtained by the parameter deciding unit 1022 and obtain an echogram
in accordance with the set imaging parameter. The imaging unit 1100
transmits the obtained echogram to the information processing unit
1000. The parameter deciding unit 1022 also sends the obtained
imaging parameter and the intersection region information used to
obtain the imaging parameter to the image generation unit 1031 of
the succeeding stage.
[0061] In step S406, the echogram acquisition unit 1030 acquires
the echogram transmitted from the imaging unit 1100, and sends it
to the image generation unit 1031 of the succeeding stage. In step
S407, the image generation unit 1031 accumulates echograms sent
from the echogram acquisition unit 1030 in the internal memory (not
shown) of the information processing unit 1000. At this time, each
echogram is associated with the imaging parameter obtained by the
parameter deciding unit 1022 or various kinds of information used
to obtain the imaging parameter, as described above.
[0062] The image generation unit 1031 generates a three-dimensional
echogram (volume data) by performing three-dimensional
reconstruction processing using the position and orientation
information of the probe and all echograms stored until this point
of time. The three-dimensional reconstruction processing can be
done using any method if the processing can reconstruct a
three-dimensional volume from a plurality of echograms. For
example, a method described in the following reference is
usable.
[0063] A. Fenster, "3-Dimensional Ultrasound Imaging," Imaging
Economics, 2004.
[0064] The above-described processes in steps S401 to S407 are
repeated in accordance with the echogram transmission rate of the
imaging unit 1100. When the user changes the position and
orientation of the probe by the same operation as in normal
diagnosis, echogram imaging is repeated, and an imaging parameter
appropriate for imaging the region of interest is set independently
of the position and orientation of the probe (that is, focus
processing is always performed for the region of interest).
Integrating the images enables to generate a three-dimensional
echogram having a focus on the region of interest.
[0065] Note that in this embodiment, the information processing
unit 1000 and the imaging unit 1100 are separate devices. However,
they may be put together into one device. The system arrangement is
not particularly limited if it can implement the above-described
functions of the embodiment. For example, it is also possible to
practice a system which forms the information processing unit 1000
in a three-dimensional medical imaging apparatus such as an MRI,
and controls the imaging parameter of the ultrasonic diagnosis
apparatus.
[0066] As described above, according to this embodiment, it is
possible to apply an imaging parameter appropriate for observing a
part of interest on an object. In addition, even if the position
and orientation of the probe change, the imaging parameter is
appropriately changed immediately following the position and
orientation of the probe. This saves re-designating the region of
interest. It is therefore possible to observe the part of interest
without degrading the operability for the user.
[0067] Furthermore, the region of interest can be designated before
imaging. The region of interest can also be designated based on
another three-dimensional image data. When a plurality of images
(each image partially includes the region of interest) obtained
based on the imaging parameter appropriate for observing the region
of interest are integrated, a high-quality image of the entire
region of interest can be obtained.
[0068] Several modifications will be explained below. These
modifications should not simply be regarded as modifications of
only the first embodiment but should be recognized as modifications
of the second or subsequent embodiment or modifications for a
combination of several embodiments.
[0069] <First Modification>
[0070] In the first embodiment, the region of interest is expressed
as a sphere. However, the method of expressing the region of
interest is not limited to this. Additionally, the
region-of-interest acquisition unit 1010 acquires the region
information of the region of interest in various forms, as
described in the first embodiment, and the acquisition method is
not limited to a specific one.
[0071] For example, the region information of the region of
interest may be acquired from a three-dimensional medical image
obtained by another modality such as an MRI or PET. In this case,
the region of a part of interest in the three-dimensional medical
image may be extracted semi-automatically or manually as the region
information of the region of interest. Examples of the region of
interest are a region being suspected to include a cancerous tumor
in volume data obtained by an MRI, and a three-dimensional region
such as a segmented organ.
[0072] The region information of the region of interest is
described as, for example, labeled volume data (a set of
three-dimensional point groups). Alternatively, the obtained region
may be approximated by a sphere or a rectangle or more simply
described using only three-dimensional coordinates representing the
position of the part of interest (central position or position of
center of gravity). A result of segmentation may be described by a
function (for example, implicit polynomial). The region-of-interest
acquisition unit 1010 acquires the region information of the region
of interest from an apparatus for performing the segmentation or an
apparatus which holds the result. Based on the thus obtained region
information, the user may perform an operation of enlarging or
reducing the region of interest via an input device such as a mouse
or a keyboard.
[0073] Note that alignment between the three-dimensional medical
image and the reference coordinate system is assumed to have
already been done by another means (that is, coordinate
transformation from the coordinate system of the three-dimensional
medical image to the reference coordinate system is assumed to be
possible). The region of interest may two-dimensionally be
designated on an echogram, and converted into the region
information of the region of interest on the reference coordinate
system based on the position and orientation information of the
probe.
[0074] <Second Modification>
[0075] In the first embodiment, the region of interest has been
described as three-dimensional shape data. However, an arbitrary
cross section in three-dimensional shape data of another medical
imaging apparatus (for example, MRI) may be designated as a region
of interest.
[0076] In this case, in step S301, three-dimensional shape data
from an MRI is displayed on a GUI by volume rendering, and a cross
section on the three-dimensional shape data from an MRI is
designated by an operation using a mouse or a keyboard. The cross
section is converted into a plane on the reference coordinate
system by coordinate transformation. In step S403, the intersection
region 504 is acquired as the line of intersection between the
plane of interest and a plane representing the imaging region of
the probe. In step S405, a focus is set for each scanning line to
the line of intersection. In step S407, each pixel value on the
line of intersection of an echogram obtained by the imaging unit
1100 may be projected as a pixel value on the plane of interest,
thereby generating a two-dimensional echogram corresponding to the
designated arbitrary cross section from an MRI. That is, according
to this modification, it is possible to acquire a high-quality
echogram in the same region as a cross section in three-dimensional
shape data of a medical imaging apparatus such as an MRI.
[0077] <Third Modification>
[0078] In the first embodiment, the imaging parameter is obtained
using the intersection region between the imaging region and the
region (region of interest) represented by region information.
However, any other method is also usable if it defines the imaging
parameter based on the positional relationship between the probe
and the region of interest (the positional relationship between an
imaging range determined based on the position and orientation
information of the probe and the region represented by region
information).
[0079] For example, even when no intersection region exists between
the imaging region and the region of interest, one point in the
imaging region closest to the region of interest may be selected,
and the distance up to the point may be set as a focus value. For
example, when the region of interest is designated by a point,
intersection with the imaging region rarely occurs. For this
reason, the coordinate value of the foot of a perpendicular from
the point of interest to the imaging plane is set as a focus
position. More simply, the depth-direction coordinate value of the
point of center of gravity of the region of interest on the probe
coordinate system may be set as a focus position.
[0080] <Fourth Modification>
[0081] In the first embodiment, the imaging parameter is a focus
position. However, any other type of parameter is also usable. For
example, STC, depth, focusing range, or sound pressure may be
adjusted.
[0082] For example, to adjust the focusing range, the imaging
parameter is adjusted in step S406 such that the line of
intersection between the scanning line 604 and the intersection
region 603 falls within the focusing range. To adjust the depth,
the intersection region between the imaging plane (a plane
including the imaging region) and the region of interest is
calculated, and the depth is adjusted such that the intersection
region is included in the imaging region. To adjust sound pressure,
the magnitude of sound pressure is adjusted in accordance with the
position of center of gravity of the target region (if the position
of center of gravity is far, the sound pressure is increased, and
if the position of center of gravity is close, the sound pressure
is reduced). Only one of these parameters may be adjusted, or a
plurality of parameters may be adjusted.
[0083] <Fifth Modification>
[0084] In the first embodiment, echograms acquired by the imaging
unit 1100 are composited to generate a three-dimensional echogram.
However, this arrangement is not always necessary. For example, the
arrangement may only control the imaging parameter of the imaging
unit 1100. In this case, it is necessary to only display an image
obtained by the imaging unit 1100 on a display device such as a
monitor.
[0085] <Sixth Modification>
[0086] In the first embodiment, an echogram is obtained using a
one-dimensional array probe for acquiring a two-dimensional image.
However, the effects described in the first embodiment can be
obtained even using a two-dimensional array probe for acquiring a
three-dimensional image, as a matter of course. In this case, the
intersection region between the region of interest and the imaging
region is a three-dimensional region on the reference coordinate
system.
[0087] <Seventh Modification>
[0088] Instead of generating three-dimensional volume data using
the whole of an acquired echogram, three-dimensional reconstruction
of only the region of interest may be done using only the
information of the region of interest. In this case, when each
pixel value of the region of interest is to be decided from a pixel
value of the intersection region 603, only several pixels of the
intersection region 603 where imaging is expected to be done
satisfactorily may be acquired as the pixel values of the region of
interest.
[0089] For example, a focusing range having a fixed length is set.
Out of line segments where the scanning lines 604 overlap the
intersection region 603, only pixels on line segments within the
focusing range may be acquired as the pixel values of the region of
interest. At this time, of the region information stored in the
region-of-interest information storage unit 1011, a region where
the pixel values of an echogram within the focusing range have been
acquired in the region of interest and a region where the pixel
values have not been acquired yet may be made identifiable. When
the processes in steps S401 to S408 are repeated for the region
where the pixel values have not been acquired yet in the region of
interest to generate an echogram of the region of interest formed
from only pixels within a specific focusing range, the whole region
of interest can be generated using the pixel values of the echogram
within the focusing range. To identify the region where the pixel
values have not been acquired, for example, a flag may be set for
coordinates, each voxel of volume data, or each pixel on a plane or
a line. Alternatively, another information representing the region
where the pixel values have not been acquired may be added.
[0090] <Eighth Modification>
[0091] In step S406, the imaging parameter may be decided in
consideration of not only the positional relationship between the
region of interest and the probe on the reference coordinate system
but also attenuation of an ultrasonic wave in the living body. For
example, the FDA (Frequency Dependent Attenuation) of the living
body through which an ultrasonic wave propagates can be specified
using the positional relationship between the region of interest
and the probe on the reference coordinate system (for example,
skin, breast, and organ). The attenuation amount of an ultrasonic
echo can be calculated for each ultrasonic frequency. The
attenuation amount of the intensity of an ultrasonic wave that
enters the region of interest and is reflected by it may be
calculated for each position and orientation of the probe. An
imaging parameter may then be decided, which unifies the intensity
of the ultrasonic wave transmitted to each point of the region of
interest or the intensity of the received ultrasonic wave.
[0092] <Ninth Modification>
[0093] In step S406, if the intersection region 603 between the
imaging region of the probe and the region of interest is included
in the imaging region 602, the direction of each scanning line may
be controlled such that the scanning lines 604 which do not overlap
the intersection region 603 can strike the region of interest. That
is, the imaging parameter may be decided such that the directions
of the scanning lines 604 change so as to make all scanning lines
of the probe overlap the intersection region 603. To change the
direction of a scanning line of the probe, the time delay of the
oscillators of the probe may be changed, or any other method is
also usable.
Second Embodiment
[0094] In this embodiment, the method of obtaining an intersection
region in accordance with the expression form (for example, sphere,
rectangular parallelepiped, or point) of a region of interest is
changed. Note that from this embodiment, only points different from
the already described embodiment will be explained. The remaining
points are assumed to be the same as in the already described
embodiment unless it is specifically stated otherwise.
[0095] <Arrangement of Ultrasonic Diagnosis Apparatus of
Embodiment>
[0096] FIG. 7 is a block diagram showing an example of the
functional arrangement of an ultrasonic diagnosis apparatus
according to this embodiment. As shown in FIG. 7, the ultrasonic
diagnosis apparatus according to this embodiment includes an
information processing unit 7100, imaging unit 1100, and position
and orientation measuring unit 1200. That is, the components other
than the information processing unit 7100 are the same as in the
first embodiment. Hence, the information processing unit 7100 will
be described below.
[0097] As shown in FIG. 7, the information processing unit 7100
includes a region-of-interest acquisition unit 1010,
region-of-interest information storage unit 1011, position and
orientation acquisition unit 1020, target region calculation unit
7121, parameter deciding unit 1022, echogram acquisition unit 1030,
and display unit 7132. That is, the components other than the
target region calculation unit 7121 and the display unit 7132 are
the same as in FIG. 1, and a description thereof is also the same
as in the first embodiment. The target region calculation unit 7121
and the display unit 7132 will mainly be explained below.
[0098] In this embodiment as well, the region-of-interest
acquisition unit 1010 acquires region information. Various
expression forms are usable for the region information, as
described in the first embodiment. For example, if the region of
interest is a point (point of interest), the three-dimensional
coordinates of the point of interest on the reference coordinate
system are acquired as region information. Alternatively, a region
of interest having a three-dimensional shape may be described using
another shape such as a rectangular parallelepiped or a
polyhedron.
[0099] The region information may be described as labeled volume
data (three-dimensional point group). Alternatively, a point group
representing the region of interest may be approximated by a
polyhedron or a polynomial. These expression methods are especially
effective when a part of interest such as a tumor is extracted, as
a region of interest, from a three-dimensional medical image
obtained in advance by another modality such as an MRI (Magnetic
Resonance Imager). In this case, preferably, the user designates a
file or the like containing region information on an MRI or an
image server connected to the ultrasonic diagnosis apparatus via a
network, and the region-of-interest acquisition unit 1010 reads it
out.
[0100] Note that when using data of another modality, alignment of
the data to the reference coordinate system is assumed to have
already been done by another means. That is, coordinate
transformation of the data to the reference coordinate system has
already been done. Alternatively, a coordinate system that defines
the image of the modality may be used as the reference coordinate
system.
[0101] Using region information stored in the region-of-interest
information storage unit 1011 and position and orientation
information sent from the position and orientation acquisition unit
1020, the target region calculation unit 7121 performs processing
of obtaining a region to be used to obtain an imaging parameter as
a target region. The target region calculation unit 7121 sends
information (target region information) representing the thus
obtained target region to the parameter deciding unit 1022 of the
succeeding stage. The target region calculation unit 7121 also
sends the region information and the position and orientation
information to the image generation unit 1031 of the succeeding
stage.
[0102] The display unit 7132 can display an echogram generated by
the image generation unit 1031 or display a GUI (Graphical User
Interface) for the user. Note that image generation by the image
generation unit 1031 and image display by the display unit 7132 can
be executed for every imaging by the imaging unit 1100 or for a
predetermined number of times of imaging or imaging in a
predetermined time. This is set by an instruction input by the
user.
[0103] <Processing Procedure to be Performed by Ultrasonic
Diagnosis Apparatus>
[0104] Processing to be performed by the ultrasonic diagnosis
apparatus according to the embodiment will be described next.
Processing to be executed by the region-of-interest acquisition
unit 1010 is the same as in the first embodiment. This processing
is performed in accordance with the flowchart shown in FIG. 3.
However, the second embodiment allows input of region information
in various expression forms.
[0105] If the region of interest is a sphere, the region
information represents the three-dimensional coordinate values of
the sphere and the radius of the sphere, as in the first
embodiment. If the region of interest is a rectangular
parallelepiped or a polyhedron, the region information represents
the coordinates of each vertex or equations representing the
position and region of the parallelepiped or polyhedron. If the
region of interest is a point (point of interest), the region
information represents the coordinates of the point of interest. If
the region of interest is labeled volume data, the region
information may represent either a point group or equations or
information representing the position and shape of the volume
data.
[0106] That is, this embodiment allows input of region information
in various forms. The region-of-interest acquisition unit 1010 may
acquire a file in which such region information is described by
reading out the file, as a matter of course. The region information
is temporarily stored in the region-of-interest information storage
unit 1011.
[0107] Processing of generating a three-dimensional echogram
including a target region will be described below with reference to
FIG. 8 which shows the flowchart of the processing. Note that the
same step numbers as in FIG. 4 indicate steps of performing the
same processes in FIG. 8, and a description thereof will not be
repeated.
[0108] Note that processing according to the flowchart of FIG. 8 is
executed after processing according to the flowchart of FIG. 3 has
ended. When the processing according to the flowchart of FIG. 8
starts, the ultrasonic diagnosis apparatus has already been
activated so as to be able to obtain an echogram, and the position
and orientation of the probe have also been measured.
[0109] In step S801, the target region calculation unit 7121
obtains a target region to be used to obtain an imaging parameter,
using the region information stored in the region-of-interest
information storage unit 1011 and the imaging region information
calculated in step S402. The target region calculation unit 7121
selects a predetermined appropriate method in accordance with the
expression form of the region of interest, and calculates the
target region using the selected method.
[0110] More specifically, when the region of interest is expressed
as a sphere, rectangular parallelepiped, polyhedron, or labeled
volume data, the intersection region between the region of interest
and the imaging region is calculated as the target region. On the
other hand, if the region of interest is expressed as a point, a
neighboring region is calculated as the target region. Note that
the association between the expression form of the region of
interest and a corresponding target region calculation method is
assumed to be done in advance and managed by the target region
calculation unit 7121.
[0111] For example, when the region of interest is a sphere, the
target region calculation unit 7121 calculates, as the target
region, the intersection region between the region of interest and
the imaging region, as in the first embodiment. For example, when
the region of interest is a rectangular parallelepiped, the target
region calculation unit 7121 calculates, as the target region, the
intersection region between the region of interest and the imaging
region, as in the case of the sphere. More specifically, a
polygonal region formed from the lines of intersection between the
respective planes of the rectangular parallelepiped and a plane
representing the imaging region is calculated as the target
region.
[0112] For example, when the region of interest is a polyhedron,
the target region calculation unit 7121 calculates, as the target
region, the intersection region between the region of interest and
the imaging region, as in the case of the sphere. More
specifically, a polygonal region formed from the lines of
intersection between all planes of the polyhedron and a plane
representing the imaging region is calculated as the target
region.
[0113] For example, when the region of interest is expressed as
labeled volume data, the target region calculation unit 7121
extracts points each corresponding to the foot of a perpendicular
which extends from a point of the volume data to a plane
representing the imaging plane and has a length within a
predetermined threshold. A region corresponding to the convex
closure of the extracted points serving as the feet of
perpendiculars to the imaging region is obtained as the target
region.
[0114] If an intersection region is distinctly defined, the
intersection region is preferably calculated as the target region.
However, when the region of interest is a point, the frequency of
generating an intersection region between the imaging region and
the region of interest is sometimes low in a normal probe
operation. In this case, as shown in FIG. 11, a perpendicular 901
is drawn from a region 501 of interest to an imaging region 503. A
neighboring region 902 generated by a point on the imaging region
503, which corresponds to the foot of the perpendicular 901, is
calculated as the target region. Using the neighboring region 902
as the target region allows to adjust the focus position of the
ultrasonic diagnosis apparatus, like an intersection region
504.
[0115] More specifically, if the region of interest is a point, the
region 501 of interest is a point of interest represented by
three-dimensional coordinates. The target region calculation unit
7121 calculates a neighboring region corresponding to the point of
interest. When the length of the perpendicular 901 drawn from the
point of interest to the imaging region 503 is equal to or less
than a predetermined threshold, the target region calculation unit
7121 calculates, as the neighboring region 902, a point serving as
the foot of the perpendicular on the imaging region 503, and
obtains the region (point) as the target region.
[0116] Note that the method of selecting a region to be obtained in
the target region calculation is not limited to the above-described
method. For example, an arbitrary method can be set such that if
the intersection region between the region of interest and the
imaging region exists, the intersection region is calculated as the
target region, and if no intersection region exists, a neighboring
region is calculated as the target region. Alternatively, the user
may input an instruction to selectively use one of an intersection
region and a neighboring region during the imaging operation.
[0117] The target region calculation unit 7121 sends information
(target region information) representing the thus obtained target
region to the parameter deciding unit 1022 of the succeeding stage.
The target region calculation unit 7121 also sends the region
information and the position and orientation information to the
image generation unit 1031 of the succeeding stage.
[0118] In step S802, the target region calculation unit 7121
determines whether the target region could be obtained in step
S801. Upon determining that the target region could not be
obtained, the process returns to step S401, and the processes in
steps S401, S402, and S801 are repeated based on the position and
orientation information of the probe input at the next time. On the
other hand, if the target region could be obtained, the process
advances to step S803.
[0119] In step S803, the parameter deciding unit 1022 obtains an
imaging parameter based on the target region information. The
process in this step is almost the same as that in step S405. For
example, independently for each scanning line, a near-side endpoint
of a line segment where a scanning line overlap the target region
is decided as a focus position. This enables to set a focus near
the boundary of the region of interest especially when the target
region is an intersection region.
[0120] Note that the focus position deciding method is not limited
to this, as described in the first embodiment. For example, to
image the entire interior of a wide region such as an organ before
deciding an optimum focus position for a specific part, the
distance up to the central point of the target region may be set as
a focus position common to all scanning lines.
[0121] Finally, in step S408, the display unit 7132 displays the
three-dimensional echogram (volume data) generated by the image
generation unit 1031. For example, to compare the image with a
cross-sectional image obtained by another modality, the display
unit 7132 displays, based on a user instruction, the
three-dimensional echogram as three cross sections that cross at
right angles.
[0122] The volume data can be displayed by any method in accordance
with the user's purpose. For example, when the user wants to
observe a three-dimensional shape, volume rendering display may be
designated. A MIP (Maximum Intensity Projection) image projected to
each plane of a rectangular parallelepiped circumscribed by the
volume data may be generated and displayed. ON/OFF of echogram
display and the display method can be either set in the ultrasonic
diagnosis apparatus in advance or switched during the imaging
operation based on a user instruction.
[0123] If execution of the image display processing in step S408 is
designated by a user instruction, the processes in steps S401 to
S408 are repeated in accordance with the transmission rate. This
allows the image generation unit 1031 to sequentially generate
three-dimensional echograms with a focus set in the region of
interest and the display unit 7132 to sequentially display the
generated three-dimensional echograms during the imaging operation
of the user.
Third Embodiment
[0124] In the second embodiment, a region of interest is designated
by making the user directly input numerical values or based on
volume data obtained from a three-dimensional image of another
modality. In the third embodiment, a region of interest is set by a
method different from that of the second embodiment. More
specifically, the user operates the probe while observing an
echogram obtained by an imaging unit 1100, and a region of interest
is set based on a region designated by the user on an echogram of
interest, unlike the second embodiment. This embodiment will be
described below concerning only points different from the second
embodiment.
[0125] <Arrangement of Ultrasonic Diagnosis Apparatus of
Embodiment>
[0126] The arrangement of an ultrasonic diagnosis apparatus
according to this embodiment is the same as in the second
embodiment except the function of a region-of-interest acquisition
unit 1010. Additionally, unlike the second embodiment, position and
orientation information acquired by a position and orientation
acquisition unit 1020 is also supplied to the region-of-interest
acquisition unit 1010, and an echogram acquired by an echogram
acquisition unit 1030 is also supplied to the region-of-interest
acquisition unit 1010.
[0127] The region-of-interest acquisition unit 1010 collects
information about a region (region of interest) designated by the
user on an echogram supplied from the echogram acquisition unit
1030. Using the collected information and the position and
orientation information supplied from the position and orientation
acquisition unit 1020, the region-of-interest acquisition unit 1010
then obtains region information that defines the region of interest
on the reference coordinate system.
[0128] <Processing Procedure to be Performed by Ultrasonic
Diagnosis Apparatus>
[0129] Processing to be performed by the ultrasonic diagnosis
apparatus according to the embodiment will be described next. The
region-of-interest acquisition unit 1010 executes the following
processing in step S301 of the flowchart of FIG. 3.
[0130] In step S301, the region-of-interest acquisition unit 1010
acquires an echogram of interest from the echogram acquisition unit
1030. This acquisition may be done based on, for example, an
instruction input by the user. The region-of-interest acquisition
unit 1010 causes a display unit 7132 to display the acquired
echogram sequentially (as a live moving image). The user designates
a region of interest while observing the echogram displayed on the
display unit 7132. For example, the user fixes the probe at a
morbid portion to display an echogram in which the morbid portion
of interest is extracted. In this state, he/she then presses a
predetermined key (to be referred to as a "still image acquisition
key" hereinafter) of the keyboard. The region-of-interest
acquisition unit 1010 causes the display unit 7132 to continuously
display, as an echogram of interest, an echogram displayed on the
display unit 7132 at the timing the user pressed the "still image
acquisition key". In addition, the region-of-interest acquisition
unit 1010 acquires, from the position and orientation acquisition
unit 1020, the position and orientation information of the imaging
unit 1100 when the echogram of interest was obtained, and stores it
in a memory (not shown).
[0131] The region-of-interest acquisition unit 1010 also collects
information about the region designated by the user on the echogram
of interest. More specifically, the region-of-interest acquisition
unit 1010 provides a GUI to be used by the user to designate a
region of interest on the echogram of interest displayed on the
display unit 7132, and collects information about the region of
interest designated by the user. Based on the collected information
and the position and orientation information supplied from the
position and orientation acquisition unit 1020 at the timing the
echogram of interest was obtained, the region-of-interest
acquisition unit 1010 obtains region information that defines the
region of interest on the reference coordinate system.
[0132] Note that to cause the user to designate a region on the
echogram of interest, for example, a method of designating a
circular region (the central point of a circle and an arbitrary
point on the circumference) on the echogram is used. A sphere
having the same center and radius as those of the designated circle
is decided as the region of interest. Note that any other method is
usable to designate a region on an image. A method of inputting a
rectangle or a free shape as in a normal paint tool may be used. A
point or a set of points on an image may be designated as a seed,
and a result of automatic extraction of a region having image
features similar to the points (or a circle that approximates the
region) may be used. When a region on an image is designated using
these methods, for example, an ellipsoid of revolution obtained by
rotating the region about an appropriate axis or the product of
ellipsoids of revolution about several axes is set as the region of
interest on the reference coordinate system. Alternatively, a
position of interest on the echogram of interest may be designated
by a point, and the region of interest may be described as the
position of the point on the reference coordinate system.
Otherwise, regions may be designated on two or more echograms of
interest by some method, and a three-dimensional region derived
from these regions by view volume intersection may be obtained as
the region of interest. The subsequent processes are the same as in
the second embodiment.
[0133] As described above, according to this embodiment, the user
can designate a region of interest while observing an echogram
obtained by the probe at an arbitrary position and orientation.
Especially, the user can designate a three-dimensional region on
the reference coordinate system as the region of interest only by
designating a two-dimensional region on a two-dimensional echogram.
In addition, since the range of an image visualized in the imaging
region can be designated as the region of interest by the same
operation and display as in a normal ultrasonic diagnosis
apparatus, the region-of-interest designation method is intuitively
understandable for the user.
Fourth Embodiment
[0134] In the above-described embodiments, a point or a
three-dimensional set of points on an object is designated as a
region of interest. In this embodiment, the form of the region of
interest is different from those in the above-described
embodiments, and a cross section on an object is designated as a
region of interest (cross section of interest). Particularly, this
embodiment is characterized by designating, as a cross section of
interest, an arbitrary cross section in a three-dimensional image
acquired by another medical imaging apparatus (for example, MRI).
This embodiment is also characterized by generating a high-quality
echogram of the same cross section as the cross section of
interest. Only points different from the second embodiment will be
explained below.
[0135] <Arrangement of Ultrasonic Diagnosis Apparatus of
Embodiment>
[0136] The arrangement of an ultrasonic diagnosis apparatus
according to this embodiment is the same as in the second
embodiment except that a region-of-interest acquisition unit 1010
acquires, as region information, information that defines a partial
region of interest on a cross section in the reference coordinate
system. The functions of a target region calculation unit 7121,
parameter deciding unit 1022, and image generation unit 1031 are
also different from those of the above embodiment to cope with the
region of interest defined as a cross section. In addition, unlike
the above-described embodiment, a display unit 7132 displays an
echogram corresponding to a cross section of interest and
information about a partial region of interest.
[0137] The region-of-interest acquisition unit 1010 acquires a
three-dimensional image of an object obtained by an MRI or the like
in advance, and causes the user to select one of a plurality of
cross sections (tomograms) included in the acquired
three-dimensional image. When the user selects one cross section
(cross section of interest), information (cross-section-of-interest
information) representing the selected cross section is generated.
The cross-section-of-interest information is expressed by, for
example, the coordinates and normal vector of one point on the
cross section.
[0138] The region-of-interest acquisition unit 1010 also collects
information (partial-region-of-interest information) representing a
region (partial region of interest) designated by the user on the
cross section of interest. Using the collected information and
position and orientation information acquired by a position and
orientation acquisition unit 1020, the region-of-interest
acquisition unit 1010 generates region information that defines the
partial region of interest on the reference coordinate system. The
generated region information is stored in a region-of-interest
information storage unit 1011, as in the above-described
embodiments. On the other hand, the partial-region-of-interest
information is sent to the display unit 7132. A more detailed
description of the region-of-interest acquisition unit 1010 and a
description of the target region calculation unit 7121, parameter
deciding unit 1022, and image generation unit 1031 will be done
later.
[0139] The display unit 7132 sequentially displays an echogram of
the same cross section as the cross section of interest generated
by the image generation unit 1031. The display unit 7132 also
superimposes the information representing the partial region of
interest on the echogram. The display unit 7132 will be described
later in more detail.
[0140] <Processing Procedure to Be Performed by Ultrasonic
Diagnosis Apparatus>
[0141] Processing to be performed by the ultrasonic diagnosis
apparatus according to the embodiment will be described next. Note
that the practice procedure of this embodiment starts when a
three-dimensional image of an object acquired by an MRI in advance
is input to the region-of-interest acquisition unit 1010.
[0142] The region-of-interest acquisition unit 1010 performs
processing according to the flowchart of FIG. 3. However, in step
S301, the region-of-interest acquisition unit 1010 performs
processing according to the flowchart of FIG. 9. FIG. 9 is a
flowchart illustrating details of the process in step S301.
[0143] In step S701, the region-of-interest acquisition unit 1010
displays, by volume rendering, a three-dimensional image acquired
from an MRI on a GUI displayed on the display unit 7132. At this
time, if a parameter to designate a cross section of interest in a
subsequent process (the process of this step is executed even after
step S702) has been set, the three-dimensional image is displayed
by volume rendering while cutting out the cross section of
interest. The image of the cross section of interest is also
displayed as a two-dimensional image without parsing. The
region-of-interest acquisition unit 1010 also displays a graphic
operation object (for example, control point) to be used to receive
a user instruction related to manipulation of the cross section.
After ending the display, the region-of-interest acquisition unit
1010 waits for an instruction input from the user.
[0144] In step S702, the region-of-interest acquisition unit 1010
determines the user operation. Upon determining that the user has
designated (updated) the cross section of interest by, for example,
operating the displayed control point, the region-of-interest
acquisition unit 1010 changes the parameter representing the cross
section of interest, and returns the process to step S701. On the
other hand, upon determining that an operation of confirming the
cross section of interest has been input, the process advances to
step S703.
[0145] In step S703, the region-of-interest acquisition unit 1010
receives a designation of a partial region of interest on the cross
section of interest. The received designation, in other words,
partial-region-of-interest information is sent to the display unit
7132. The partial region of interest is a partial region including
a possible morbid or abnormal portion such as a cancerous tumor the
operator wants to note on the cross section of interest (of which
the operator wants to obtain an echogram). As the partial region of
interest, for example, a circular, elliptic, rectangular, or other
region is designated, based on an operation instruction from the
user, on the two-dimensional image of the cross section of interest
of the MRI displayed on the display unit 7132 in step S701. FIG. 12
is a view showing the relationship between volume data 1001, cross
section 1002 of interest, morbid portion 1003, and partial region
1004 of interest of an MRI.
[0146] Note that as another method of designating the partial
region of interest, the region-of-interest acquisition unit 1010
may acquire information about the position of a morbid region
extracted automatically or manually by another means from the
three-dimensional image of the MRI, and designate the partial
region of interest based on the information. In this case, for
example, a morbid region on the cross section 1002 of interest may
directly be used as the partial-region-of-interest information.
Alternatively, for example, an elliptic or rectangular region
including a morbid region may be used as the
partial-region-of-interest information.
[0147] Referring back to FIG. 9, in step S704, the
region-of-interest acquisition unit 1010 converts the parameter
representing the cross section of interest designated by the
processes in steps S701 and S702 into a description based on the
reference coordinate system. This allows to generate region
information that defines the region of interest on the reference
coordinate system. In step S302, the region information is stored
in the region-of-interest information storage unit 1011.
[0148] Processing of generating a three-dimensional echogram with a
focus on the cross section of interest will be described below with
reference to FIG. 8 which shows the flowchart of the processing.
Note that the processing of generating a three-dimensional echogram
with a focus on the cross section of interest is implemented by
making the following changes in the flowchart of FIG. 8.
[0149] Steps S401 and S402 are the same as in the second
embodiment. In step S801, the target region is calculated based on
the positional relationship between the imaging region and the
region of interest, as in the second embodiment. In this
embodiment, as shown in FIG. 10, an intersection region defined as
a line 801 of intersection between a plane representing the region
of interest and a plane representing the imaging region of the
probe is calculated as the target region.
[0150] Step S802 is the same as in the second embodiment. In step
S803, the parameter deciding unit 1022 decides the imaging
parameter (the focus position of each scanning line) based on the
target region obtained in step S801, as in the second embodiment.
In this embodiment, as shown in FIG. 10, the intersection between
each scanning line and the line 801 of intersection obtained in
step S801 is set as the focus position of the scanning line. Step
S406 is the same as in the second embodiment.
[0151] In step S407, the image generation unit 1031 stores
echograms obtained by the imaging unit 1100, and integrates all
echograms stored until this point of time, thereby generating an
echogram of the cross section of interest (corresponding to the
cross section of interest), as in the second embodiment. For
example, as in the second embodiment, after a three-dimensional
echogram is generated, an image is generated by cutting out the
same cross section as the cross section of interest from the
three-dimensional echogram using a known technique. Note that the
image generation processing of this step is preferably high-speed
processing that is repeatedly executable in accordance with the
echogram transmission rate of the imaging unit 1100. Hence, as a
suitable technique for the image generation processing, a
three-dimensional echogram generated in the process of the step one
cycle before is held and then updated using an echogram newly
acquired in step S406.
[0152] Note that the method of generating the echogram of the cross
section of interest is not limited to this. The image of the cross
section of interest may be generated without intervening a
three-dimensional echogram. For example, the values of pixels on
the line 801 of intersection on each obtained echogram are
sequentially plotted on an image to be generated, thereby
generating a desired image without intervening a three-dimensional
echogram.
[0153] In step S408, the display unit 7132 displays the echogram of
the cross section of interest generated in step S407. Additionally,
as shown in FIG. 13, an indicator (a dotted circle in FIG. 13) that
points out the position of the partial region 1004 of interest is
displayed on an image 1101 of the cross section of interest. Note
that this image is preferably displayed by the side of the image of
the cross section of interest of the MRI, as in step S701.
Especially, when images of two modalities are displayed at the same
magnification, the user can easily grasp the correspondence between
the modalities.
[0154] Note that the image display form in step S408 is not limited
to the above-described one. For example, MRI volume rendering may
be performed as in step S701, and the generated echogram may be
superimposed on (or replaced with) the portion of the cross section
of interest. A frame (wireframe) or plane representing the imaging
region of the echogram may be displayed on the same coordinate
system as that of the volume rendering. The echogram acquired in
step S406 may be displayed (for example, semitransparently) in the
imaging region. Such display facilitates to grasp the positional
relationship between the cross section of interest and the probe.
Note that the display form to be used in step S408 is preferably
selectable based on an instruction input by the user.
[0155] As shown in FIG. 14, the display unit 7132 can display, in
accordance with an instruction input by the user, a high-quality
region 1201 in the image 1101 of the cross section of interest
distinguishably in a tone of color or luminance different from
other regions. The high-quality region 1201 is, for example, a
region formed from pixels which are generated using echograms equal
to or more than a threshold when generating the pixels of the image
of the cross section of interest using obtained echograms. As is
generally known, when reconstructing an image using a plurality of
echograms, the image quality rises as the number of echograms used
increases. Also, the high-quality region is a region on the cross
section of interest formed from pixels each having a distance from
a focus position equal to or less than a predetermined threshold in
an obtained echogram. A pixel having a predetermined distance or
less from a focus position is obtained more accurately than a pixel
far apart more than the predetermined distance. Hence, a region
reconstructed from such pixels has image quality higher than that
of other regions.
[0156] The above-described processing is repeated in accordance
with the echogram transmission rate of the imaging unit 1100. As a
result, when the user changes the position and orientation of the
probe by the same operation as in normal diagnosis, echogram
imaging is repeated, and an imaging parameter appropriate for
observing the cross section of interest is set independently of the
position and orientation of the probe (that is, focus processing is
always performed for the cross section of interest). Integrating
the images enables to generate a high-quality echogram of the cross
section having a focus on the cross section of interest.
[0157] When the above-described processing is repeated in
accordance with the transmission rate, the echograms of the cross
section of interest are sequentially generated during the user's
imaging operation, and the generated echograms (at that point of
time) are sequentially displayed. This allows the user to determine
whether imaging is sufficient or whether the imaging position is
appropriate while visually observing a target echogram. In
addition, superimposing information about the position of the
partial region of interest allows the user to confirm, at a glance,
the position of a morbid portion (to be imaged by ultrasonic waves)
visualized on the cross section of interest of the MRI or whether
the image at that portion has been generated. It is consequently
possible to efficiently acquire desired echograms. The
above-described procedure makes it possible to obtain a
high-quality echogram corresponding to the cross section of
interest of the MRI by an efficient operation.
[0158] Note that in this embodiment, the processes in steps S407
and S408 are executed for each acquired frame. However, the
processes need not always be executed for each acquired frame. For
example, if the processes in steps S407 and S408 cannot be done in
a full frame, they may be executed in the background for every
several frames. Alternatively, the processes in steps S407 and S408
may be executed after imaging processing in steps S401 to S406 has
been executed for sufficient frames.
[0159] Note that in this embodiment, a two-dimensional image has
been exemplified as the partial region of interest on the cross
section of interest. However, the embodiment can also be practiced
for a partial region of interest in a three-dimensional region of
interest.
[0160] <First Modification>
[0161] In the above-described embodiment, an imaging parameter is
decided, and the imaging unit 1100 is controlled using the decided
imaging parameter. However, the decided imaging parameter may be
set manually by the user. In this case, an information processing
unit 7100 displays the decided imaging parameter on the display
unit 7132. The user views the display, and manually sets the
displayed imaging parameter in the imaging unit 1100.
[0162] <Second Modification>
[0163] In the above embodiment, an ultrasonic diagnosis apparatus
for measuring an ultrasonic echo has been described as an example
of an image diagnosis apparatus. However, the image diagnosis
apparatus may be another modality. For example, the image diagnosis
apparatus may be a PAT (Photo-Acoustic Tomography) apparatus which
images an object using a probe having a laser beam source and an
ultrasonic probe for reception. In this case, for example, the
laser intensity can be adjusted as the imaging parameter in
accordance with the position of the target region on the imaging
region. Note that the above-described various embodiments and
modifications may be combined as needed.
Fifth Embodiment
[0164] In the above-described embodiments, all of the units
included in the information processing unit 1000 shown in FIG. 1
and the units included in the information processing unit 7100
shown in FIG. 7 are formed from hardware. However, the
region-of-interest information storage unit 1011 may be implemented
by a memory, the display unit 7132 by a monitor, and the remaining
units by computer programs. In this case, a computer including the
region-of-interest information storage unit 1011 as a memory, the
display unit 7132 as a monitor, and a CPU for executing the
remaining units as computer programs functions as the information
processing unit 1000 or 7100.
[0165] FIG. 2 is a block diagram showing an example of the hardware
configuration of a computer applicable to the information
processing unit 1000 or 7100.
[0166] A CPU 100 controls the entire computer using computer
programs and data stored in a main memory 101, and also executes
the above-described processing of the information processing unit
1000 or 7100.
[0167] The main memory 101 has an area for temporarily storing
computer programs and data loaded from a magnetic disk 102, data
received from an external device via an I/F (interface) 106, and
the like. The main memory 101 also has a work area to be used by
the CPU 100 to execute various kinds of processing. That is, the
main memory 101 can provide various kinds of areas as needed. The
main memory 101 also functions as, for example, the
region-of-interest information storage unit 1011.
[0168] The magnetic disk 102 is a mass information storage device
functioning as a hard disk drive. The magnetic disk 102 stores the
OS (Operating System), and computer programs and data to cause the
CPU 100 to execute the functions of units other than the
region-of-interest information storage unit 1011 and the display
unit 7132 in FIGS. 1 and 7. The data include known data described
above and process target data. The computer programs and data
stored in the magnetic disk 102 are loaded to the main memory 101
as needed under the control of the CPU 100, and processed by the
CPU 100.
[0169] An input unit 105 is formed from a keyboard and a mouse
which the user can operate to input various instructions and data.
All instructions and data input by the user in the above
explanation are input by causing the user to operate the input unit
105.
[0170] The I/F 106 connects the position and orientation measuring
unit 1200 and the imaging unit 1100 to the computer, and is formed
from IEEE1394, USB, Ethernet.RTM. port, or the like. The computer
performs data communication with the position and orientation
measuring unit 1200 and the imaging unit 1100 via the I/F 106.
[0171] A display memory 103 temporarily stores data of a screen to
be displayed on a monitor 104. The monitor 104 displays a screen
based on the screen data stored in the display memory 103.
[0172] The monitor 104 is formed from a CRT or a liquid crystal
display so as to display the processing result of the CPU 100 as an
image or characters. The monitor 104 functions as the display unit
7132. A bus 107 connects the above-described units.
[0173] Note that the arrangement of an apparatus applicable to the
information processing unit 1000 or 7100 is not limited to that
shown in FIG. 2. Any other arrangement is usable if it can
implement the functional arrangement shown in FIG. 1 or 7.
Other Embodiments
[0174] The present invention is also achieved by executing the
following processing. Software (program) which implements the
functions of the above-described embodiments is supplied to a
system or apparatus via a network or various kinds of storage
media. The computer (or CPU or MPU) of the system or apparatus
reads out and executes the program.
[0175] The present invention is not limited to the above
embodiments, and various changes and modifications can be made
within the spirit and scope of the present invention. Therefore, to
apprise the public of the scope of the present invention, the
following claims are appended.
[0176] This application claims the benefit of Japanese Patent
Application No. 2009-112294, filed May 1, 2009, which is hereby
incorporated by reference herein in its entirety.
* * * * *