JP2001145631A - Ultrasonic diagnostic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To properly and automatically set the range of a three-dimensional image in an ultrasonic diagnostic device. SOLUTION: Smoothing processing is executed to a received signal to specify both of the ends of a data falling part included in the received signal. A boundary point is set as a middle point between both of them. The boundary point is used as the start point of a three-dimensional picture processing. It is also possible to integrate the received signal after being smoothed and then specifying both ends of the data falling part from the inclination of the integrated waveform. It is possible to extract data on only a fetus in amniotic fluid by the methods.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic diagnostic apparatus, and more particularly to an apparatus for forming a three-dimensional ultrasonic image.

[0002]

2. Description of the Related Art Various apparatuses have been proposed as apparatuses for forming three-dimensional ultrasonic images. For example, JP-A-10-33538 proposes a three-dimensional image processing method based on a volume rendering method. In this method, pixel values are calculated for each ultrasonic beam by sequentially executing predetermined voxel operations by referring to individual echo data present on each ultrasonic beam in the order of their time series. Then, a three-dimensional image is formed as a set of such pixel values.

In the above-described apparatus, for example, FIG.
As shown in the figure, a simple straight line 12 having a constant depth is set with respect to the scanning plane 10, and image processing is performed in the direction along each ultrasonic beam using the straight line 12 as a calculation start point, and the amniotic fluid 2
When trying to form an image of fetus 16 that resides in zero,
Since the placenta 18 is imaged or a part of the fetus 16 is missing, it is difficult to form an image of the entire target fetus. On the other hand, as shown in FIG.
When the line 22 is manually drawn around the line 6 and the calculation start point is specified by this, there is a problem that the operation is complicated and time-consuming.

[0004] The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to provide an apparatus capable of appropriately and automatically setting an imaging range.

It is another object of the present invention to provide an apparatus capable of accurately forming a fetus in amniotic fluid as a three-dimensional image.

[0006]

(1) In order to achieve the above object, the present invention provides a transmitting / receiving means for forming a data capturing space by scanning an ultrasonic beam, Boundary point setting means for determining a dip portion of the echo data before the target object and setting a boundary point in the dip portion of the echo data for each search axis set by Pixel value calculation means for calculating a pixel value by sequentially referring to echo data from the calculation start point along the projection axis with a boundary point on the projection axis as a calculation start point for each projection axis to be calculated; Display means for displaying an ultrasonic image as a set of pixel values for each of the projection axes,
It is characterized by including.

[0007] According to the above configuration, the echo data drop portion (feature data portion) located in front of the target object existing in the two-dimensional or three-dimensional data capture space is used to appropriately position the target object in front of the target object. After setting a boundary point, image processing can be performed using the boundary point as a calculation start point.

[0008] The echo data drop portion before the target object is
It is mainly observed when there is liquid such as around or inside the real tissue, for example, fetus in amniotic fluid, heart, blood vessels,
It is observed when the bladder and the like are to be diagnosed. Needless to say, other cases may be observed when the bone and the soft tissue are in contact with each other. That is, the present invention is particularly preferably applied to the diagnosis of a fetus, but is not limited thereto.

Conventionally, there has been a method of determining the tissue surface by comparing the echo intensity with a threshold value. However, the present invention is different from that, in which a boundary point is appropriately set in front of the tissue. According to this method, for example, when performing volume rendering, data calculation is started from before the organization,
Echo data corresponding to the tissue surface can be used for calculation without omission.

Preferably, the wave transmitting / receiving means scans an ultrasonic beam to form a three-dimensional data capturing space, and the search axis and the projection axis are set with respect to the three-dimensional data capturing space. Preferably, the search axis matches the projection axis. Preferably, the search axis and the projection axis coincide with an ultrasonic beam.

Preferably, the boundary point setting means executes a smoothing process on the echo data sequence on the search axis, and detects both ends of the data drop portion in the smoothed echo data sequence. Means for setting the boundary point at the center between the two ends.

If the data drop portion is specified after performing the smoothing, the influence of noise can be eliminated and the specification accuracy can be improved. Although the edge of the target tissue is also smoothed by the smoothing, the smoothing is performed as a pre-process for detecting the boundary points, and does not affect the image quality of the ultrasonic image.

Preferably, the boundary point setting means performs a smoothing process on the echo data sequence on the search axis, and performs an integration process on the smoothed echo data sequence. Means for calculating the slope of each position of the waveform generated by the integration, and means for specifying the dip portion of the echo data based on the slope and setting the boundary point at the center thereof.

According to the above configuration, the overall fluctuation tendency of the echo data size can be grasped by integration, and the inclination of the waveform can be analyzed to improve the accuracy of specifying the data drop portion.

In order to achieve the above object, the present invention provides a transmitting / receiving means for forming a data acquisition space by scanning an ultrasonic beam, and a plurality of directions different from each other with respect to the data acquisition space. A search axis setting means for setting a plurality of search axes from; and, for each of the search axes, a boundary point setting means for judging a dip portion of the echo data before the target object and setting a boundary point in the echo data dip portion And, for each projection axis set for the data acquisition space, with a boundary point on the projection axis as a calculation start point, sequentially referring to echo data from the calculation start point along the projection axis. It is characterized by including a pixel value calculating means for calculating a pixel value, and a display means for displaying an ultrasonic image as a set of pixel values for each projection axis.

According to another aspect of the present invention, there is provided a transmission / reception means for forming a data acquisition space by scanning an ultrasonic beam, and a plurality of directions different from each other with respect to the data acquisition space. A search axis setting means for setting a plurality of search axes from; and, for each of the search axes, a boundary point setting means for judging a dip portion of the echo data before the target object and setting a boundary point in the echo data dip portion Extracting means for extracting echo data in a target object-containing area surrounded by the plurality of boundary points; and image forming means for forming an ultrasonic image of the target object using the extracted echo data. It is characterized by.

Preferably, the data capture space is a three-dimensional data capture space, and the ultrasound image is a three-dimensional ultrasound image.

(2) Here, a desirable embodiment of the present invention will be described. FIG. 3 shows an echo data sequence on a certain ultrasonic beam, that is, a received signal. In FIG. 3, the vertical axis indicates the level of the echo data, that is, the amplitude of the received signal. This received signal includes an echo data drop portion 20 corresponding to amniotic fluid between the placenta and the fetus.
0 has occurred. Therefore, it is possible to set a boundary point outside the fetus by using such an echo data drop portion 200. However, if the echo data drop portion 200 is simply specified by the threshold value K, there is a high possibility that a portion other than amniotic fluid will be detected. Therefore, desirably, as shown in FIG. 4, a smoothing process is performed on the received signal, low-pass filtering is performed on the received signal, and a section moving averaging process is further performed. It is desirable to specify the echo data dip portion 200 in a state where noise is removed from. In the example shown in FIG. 4, one or more thresholds E1, E2
Is used, a point at which the level of the received signal falls below the threshold value E1 is specified as n1, and thereafter, a point at which the level of the received signal exceeds the threshold value E2 is specified as n2. Then, a boundary point is specified as an intermediate point between n1 and n2.

Alternatively, an integration process is performed on the smoothed received signal shown in FIG. 4 to obtain an integrated waveform as shown in FIG. 5, and the inclination of each position is calculated with respect to the integrated waveform. Alternatively, both ends of the dip portion of the echo data may be specified based on the inclination. In the example shown in FIG. 6, the slopes at two points separated by a certain distance L are sequentially calculated (see a1, a2, and a3), and a point t1 at which such a slope becomes smaller than a predetermined threshold value A1 and then a point t1 A point t2 that is larger than the slope threshold A2 is specified as both ends of the data drop portion, and a boundary point is set as an intermediate point between them.

The above method will be described in detail below using a calculation formula.

[0021] Now, when the received signal and e _i, the signal after smoothing as shown in FIG. 4 is expressed as follows.

[0022]

(Equation 1) Assuming that a point at which the above value becomes smaller than a certain threshold value E1 is n1, and a point at which the value becomes larger than E2 is n2, a section between n1 and n2 is a data drop portion, that is, a portion of amniotic fluid. it is conceivable that. As a representative value of n2>N> n1, for example, N = (n1 + n2) / 2,
It is possible to determine a point in the amniotic fluid.

Alternatively, when the signal shown in FIG. 4 is integrated, the integrated value is expressed as follows.

[0024]

(Equation 2) For such an integrated waveform, the slope between two points is calculated, and it is sequentially calculated while changing the location. The slope is expressed as follows.

[0025]

(Equation 3) Then, an average value of the slopes of several consecutive points is obtained, and the average value of the slopes is compared with a threshold value. The averaged slope is expressed as follows.

[0026]

(Equation 4) The point at which the average value becomes smaller than a certain threshold value A1 is defined as t
When the point at which the average value of the slope becomes larger than the threshold value A2 is set to t2, both ends of the amniotic fluid can be specified, and T = (t1 + t2) / 2 can be determined as the intermediate point. Become.

As described above, if a boundary point is set at a position that is considered to be intermediate between the amniotic fluids, a calculation such as volume rendering is performed from the boundary point, so that the echo data on the surface of the fetus can be completely captured. It can be used for processing, and a clearer image can be drawn. That is, the line 22 as shown in FIG. 2 can be automatically and appropriately set.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings.

FIG. 7 is a block diagram showing a preferred embodiment of the ultrasonic diagnostic apparatus according to the present invention.

The transmitter / receiver 24 is constituted by an ultrasonic probe for transmitting / receiving ultrasonic waves, a transmitting / receiving unit, and the like, and a received signal is output from the transmitter / receiver 24 to the detection circuit 26. The detection circuit 26 detects a received signal and outputs the detected signal to the 3D image processing unit 32. This will be described later in detail.

The received signal output from the detection circuit 26 is
The signal is also input to the signal processing unit 28. The signal processing unit 2
In 8, the low-pass filter 36 is a filter that passes only low-frequency components on the received signal, and the received signal after the filter is input to the moving averager 38.
The moving averager 38 performs a section moving averaging process on the received signal, that is, a circuit that performs the averaging process while sequentially shifting a certain section in the time axis direction. By this averaging process, a received signal after smoothing as shown in FIG. 4 can be obtained.

The switch 40 is a circuit for selecting whether to set the boundary point by the method described with reference to FIG. 4 or to set the boundary point by applying the method shown in FIGS. 5 and 6. is there. Here, when the method shown in FIG. 4 is selected, the comparator 42 compares the smoothed received signal with threshold values E1 and E2. That is, n1 and n2 shown in FIG. 4 are specified. Then, the imaging range determiner 30
Performs the calculations described above and determines the boundary point as the midpoint between n1 and n2. The boundary point is the 3D image processing unit 32
Is output to

5 and FIG.
Is selected, the received signal after the smoothing is input to the integrator 44, whereby the integrated waveform shown in FIG. 5 is generated. Then, in the differentiator 46, a slope calculation is sequentially performed on the integrated waveform. Next, the slopes sequentially obtained in the averager 48 are averaged. In the comparator 50, the averaged slope and the threshold values A1, A
2 are compared with each other, and as described above, points t1 and t2 corresponding to both ends of the dip portion of the echo data are specified.

Then, the imaging range determining unit 30 sets a boundary point as an intermediate point between the two points t1 and t2 based on the two points t1 and t2.

Accordingly, the coordinates of the boundary point are input to the 3D image processing section 32 for each ultrasonic beam or for each predetermined data string, and the 3D image processing section 32 uses the boundary point as the calculation start point. Perform image processing such as volume rendering.

Specifically, the 3D image processing section 32
By referring to each echo data in the time-series order with respect to the echo data sequence in the time-series order along the ultrasonic beam, and performing a predetermined voxel operation for each echo data, finally, for each ultrasonic beam, In this case, the echo data referred first is the echo data on the boundary point. The details of the voxel calculation are also described in, for example, the above-mentioned Japanese Patent Application Laid-Open No. 10-33538. However, it is not limited to the method described therein, and various image processing can be applied.

It is to be noted that a buffer or the like for temporarily storing echo data may be provided in the 3D image processing unit 32 in consideration of the processing time of the signal processing unit 28 and the imaging range determination unit 30. The three-dimensional image formed by the 3D image processing unit 32 is displayed on the display unit 34.

FIG. 8 is a block diagram showing an ultrasonic diagnostic apparatus according to another embodiment. The operation will be described with reference to FIG. 9. For example, when a fetus 16 is present in the scanning plane 10, a plurality of orientations different from each other are set in order to set a boundary line 90 in amniotic fluid outside the fetus 16. Search axis 200 is set. In this case, search axis groups parallel to each other may be set from different directions, or a plurality of search axes are set along a plurality of directions by rotating one search axis about the fetus 16. You may do so. In any case, a plurality of search axes are set from the periphery of the fetus 16 in directions different from each other, and echo data is sequentially referred to from each search axis from the search origin, as shown in FIG. 4 or FIG. If a boundary point is obtained as an intermediate point of a data drop portion by the above method, it is possible to draw a boundary line 90 as a connection of those boundary points.

If such a boundary line 90 is completed as a closed loop, a closed region including the fetus 16 can be formed in the scanning plane 10. For example, when the fetus 16 is imaged, an image other than the closed region is formed. Data, for example, an image of the placenta can be removed from the display. Further, there is an advantage that the storage capacity can be reduced by storing the echo data of only the fetus portion in the memory.

In the configuration shown in FIG. 8, the diagnostic signal output from the transmitter / receiver 52 is input to the detection circuit 54, and the detection of the received signal is executed. The received signal after the detection is temporarily stored in the memory 56. The read control unit 58 is a unit that controls reading of echo data from the memory 56. The search axis setting unit 60 is means for artificially or automatically setting a plurality of search axes from a plurality of directions with respect to the data acquisition space. When the search axis is set in this manner, the read control unit 58 reads the echo data on the search axis from the memory 56, that is, reads the echo data sequence corresponding to the search axis and outputs the echo data sequence to the signal processing unit 62. The signal processing unit 62 has the same configuration as the signal processing unit 28 shown in FIG. 7, and the processing result is passed to the imaging range determination unit 64. The imaging range determiner 64 has the same configuration as the imaging range determiner 30 shown in FIG.

Thus, the boundary point on the echo data sequence is set by the imaging range determination unit 64, and the coordinates of the boundary point are output to the read control unit 58. The coordinates of the boundary points on each search axis set by the search axis setting unit 60 are input to the read control unit 58, and the read control unit 58 sets these boundary points as data read start points. The echo data is read out along the search axis, along a predetermined line of sight, or along the ultrasonic beam, and is output from the memory 56 to the display unit 66.

As a result, as shown in FIG. 9, for example, an image of only the fetus 16 surrounded by the boundary 90 can be displayed. By the way, the search axis 200 is a boundary 90 as a closed loop at least around the target object.
May be set as long as can be formed. For example, a plurality of search axes 200 parallel to each other may be set from four directions around the target object, and a boundary point may be determined on each of these search axes. .

When echo data is referred to from the search origin on the search axis, a boundary point can be set on the near side of the target object, and theoretically, the boundary point can be set on the opposite side of the target object. However, since the level of the echo data in such a deep portion is extremely weak, it is desirable to set a search axis in the opposite direction on the opposite side and separately set a boundary point.

FIG. 10 shows another configuration example.
The operation will be described with reference to FIG. 11. FIG. 11 shows a fetus 102 existing in the three-dimensional data capturing space 100. In order to set the closed curved surface 92 so as to enclose the fetus 102 three-dimensionally, search axes 202 are set for all directions of the fetus 102. Then, a boundary point is detected on the search axis by each of the above methods, and a closed curved surface 92 is formed with the boundary point as a continuous surface.

When the closed curved surface 92 is formed in the three-dimensional data capturing space 100 in this manner, it is possible to three-dimensionally extract the data of the fetus 102, and conversely, echo data of the placenta and the like. Can be excluded from imaging targets. That is, as shown in FIG. 12, only data corresponding to the fetus 102 can be extracted from the three-dimensional space.

In the configuration shown in FIG.
The received signal output from the 3D memory 72 is detected by the detection circuit 70, and the received signal after the detection, that is, the echo data is
Is stored once. The read control unit 74 sets the 3D memory 7 along each search axis set by the search axis setting unit 76.
2 is read out, that is, the signal processing unit 78 outputs an echo data string corresponding to the search axis. The signal processing unit 78 has the same configuration as the signal processing unit 28 shown in FIG. 7, and the imaging range determination unit 80 has the same configuration as the imaging range determination unit 30 shown in FIG. The boundary point is obtained on each search axis by the action of. The coordinates of the boundary point are output to the read control unit 74. A line-of-sight setting device 82 in the configuration example shown in FIG. 10 is connected to the read control unit 74. The line-of-sight setting device 82 sets the direction or coordinates of the line of sight automatically or by manual setting.

The read control unit 74 specifies a boundary point on each line of sight, and reads echo data from the 3D memory 72 along the line of sight using the boundary point as a data read start point. The read echo data is sent to the 3D image processing unit 84 for each line of sight, and the 3D image processing unit 84 executes volume rendering processing and the like for each line of sight,
Finally construct a three-dimensional image. The three-dimensional image is displayed on the display unit 86.

As described above, according to the configuration example shown in FIG. 10, the search axis and the line of sight can be set separately, and they do not always need to coincide with the ultrasonic beam. It is possible to display a target object existing in a 3D image from a desired direction.

In FIG. 11, the search axis 202 is desirably set from all directions around the target object. However, the search axis 202 is not necessarily limited thereto. A plurality of parallel search axis groups may be set based on the azimuth, and the boundary point group forming the closed curved surface 92 may be specified thereby.

FIG. 13 is a flowchart showing an operation example of the ultrasonic diagnostic apparatus shown in FIG. First, in S101, it is determined whether the setting of the boundary point for the three-dimensional data capturing space has already been completed, and if not completed, the steps from S102 are executed.

In S102, a search axis is set in the data acquisition space by the search axis setting unit 76 shown in FIG. 10, and in S103, a process of determining a boundary point for the echo data sequence on the search axis is executed. .

In S104, the coordinates of the boundary point are stored in a predetermined memory. In S105, it is determined whether or not the determination of the boundary points has been completed for all the search axes. If not, the search axes are changed in S106, and the search axes are changed in S10.
Steps from 2 are repeatedly executed.

In S107, since the boundary points are specified for all the detection points in the data acquisition space, only the echo data in the area surrounded by the boundary points is extracted. An echo data portion of the fetus as shown in FIG. 12 (including echo data of amniotic fluid in part) is extracted. S
At 108, a plurality of lines of sight are set from a desired direction with respect to such an extracted data space, and at S109, a three-dimensional image is formed by performing a predetermined voxel operation while referring to echo data along the line of sight. You. Then, in S110, the three-dimensional image is displayed.

In step S107, the echo data of the target organ is extracted. Therefore, for example, when only the line of sight is changed, the process proceeds from step S101 to step S108, and the process proceeds to step S102.
To S107 can be omitted. That is, there is an advantage that a three-dimensional image can be quickly formed even if the line of sight is changed.

[0055]

As described above, according to the present invention,
The range of three-dimensional imaging can be appropriately and automatically set. Further, according to the present invention, there is an advantage that, for example, only a fetus can be clearly expressed as a three-dimensional image.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating setting of a calculation start point by a line.

FIG. 2 is a diagram illustrating setting of a calculation start point by manual setting.

FIG. 3 is a diagram illustrating a reception signal.

FIG. 4 is a diagram illustrating a method of specifying a smoothed received signal and a data drop portion.

FIG. 5 is a diagram showing a waveform obtained by integrating a smoothed received signal.

FIG. 6 is a diagram for explaining a slope calculation on an integrated waveform.

FIG. 7 is a block diagram of an ultrasonic diagnostic apparatus according to the embodiment.

FIG. 8 is a block diagram of an ultrasonic diagnostic apparatus according to another embodiment.

9 is a diagram for explaining the processing principle of the ultrasonic diagnostic apparatus shown in FIG.

FIG. 10 is a block diagram of an ultrasonic diagnostic apparatus according to another embodiment.

11 is a diagram for explaining the processing principle of the ultrasonic diagnostic apparatus shown in FIG.

12 is a diagram for explaining the processing principle of the ultrasonic diagnostic apparatus shown in FIG.

FIG. 13 is a flowchart for explaining the operation of the apparatus shown in FIG.

[Explanation of symbols]

24 transceiver, 26 detection circuit, 28 signal processing unit,
30 imaging range determiner, 32 3D image processing unit, 34
Display section, 36 low-pass filter, 38 moving averager, 42 comparator, 44 integrator, 46 differencer, 48
Averager, 50 comparators.

Claims (10)

[Claims] 1. A transmitting / receiving means for forming a data capturing space by scanning an ultrasonic beam, and for each search axis set for the data capturing space, an echo data drop portion in front of a target object is formed. A boundary point setting means for determining and setting a boundary point in the echo data drop portion; and for each projection axis set for the data capture space, a boundary point on the projection axis is calculated. Pixel value calculation means for sequentially calculating pixel values by sequentially referring to echo data from the calculation start point along the projection axis, and an ultrasonic image as a set of pixel values for each projection axis is displayed An ultrasonic diagnostic apparatus comprising: a display unit. 2. The apparatus according to claim 1, wherein the transmitting / receiving means scans an ultrasonic beam to form a three-dimensional data capturing space, and the search axis and the projection axis are the three-dimensional data capturing space. An ultrasonic diagnostic apparatus characterized by being set for: 3. The ultrasonic diagnostic apparatus according to claim 1, wherein the search axis and the projection axis coincide with each other. 4. An ultrasonic diagnostic apparatus according to claim 1, wherein said search axis and said projection axis coincide with an ultrasonic beam. 5. The apparatus according to claim 1, wherein the boundary point setting unit performs a smoothing process on the echo data sequence on the search axis, and performs the smoothing process on the echo data sequence after the smoothing. An ultrasonic diagnostic apparatus comprising: means for detecting both ends of a data drop portion; and means for setting the boundary point at the center between the both ends. 6. The apparatus according to claim 1, wherein the boundary point setting unit executes a smoothing process on the echo data sequence on the search axis, and performs a smoothing process on the echo data sequence after the smoothing. Means for calculating the slope of each position of the waveform generated by the integration processing; identifying the dip portion of the echo data based on the slope; and setting the boundary point at the center thereof. Means, and an ultrasonic diagnostic apparatus comprising: 7. The ultrasonic diagnostic apparatus according to claim 1, wherein the boundary point setting means sets the boundary point in amniotic fluid just before a fetus. 8. A transmitting and receiving means for forming a data acquisition space by scanning an ultrasonic beam, and a search axis setting means for setting a plurality of search axes from a plurality of different directions with respect to the data acquisition space. For each of the search axes, a boundary point setting means for determining a echo data dip portion before the target object, and setting a boundary point in the echo data dip portion, and which is set for the data capture space. Pixel value calculation means for calculating a pixel value by sequentially referring to echo data from the calculation start point along the projection axis with a boundary point on the projection axis as a calculation start point for each projection axis; Display means for displaying an ultrasonic image as a set of pixel values for each projection axis. 9. A transmitting and receiving means for forming a data acquisition space by scanning an ultrasonic beam, and a search axis setting means for setting a plurality of search axes from a plurality of different directions with respect to the data acquisition space. For each of the search axes, a boundary point setting means for determining a dip portion of the echo data before the target object and setting a boundary point in the dip portion of the echo data; and a target object surrounded by the plurality of boundary points. An ultrasonic diagnostic apparatus comprising: an extracting unit that extracts echo data in a contained space; and an image forming unit that forms an ultrasonic image of the target object using the extracted echo data. 10. The ultrasonic diagnostic apparatus according to claim 9, wherein the data acquisition space is a three-dimensional data acquisition space, and the ultrasonic image is a three-dimensional ultrasonic image.