JP2000325347A - Ultrasonic diagnostic apparatus and method of restructuring three-dimensional image data - Google Patents

Abstract

PROBLEM TO BE SOLVED: To collect three-dimensional image data in the state of a tomographic image including spatial position data without redundancy at the time of scanning with a manually moved probe even if the moving speed is unsteady for recomposing the image, and use the image data for restructuring images. SOLUTION: This apparatus has scanning means 12, 21, 22, 32, etc., for scanning each cross-section of the three-dimensional area of a subject with ultrasonic beams and collecting echo signals, and data producing means 24-27 for producing three-dimensional image data from the echo signals. The apparatus also has spatial position information detecting means 15, 30, 31 for detecting information on the spatial position of each cross-section of the three-dimensional area at the time of scanning by the scanning means and an optimization means 26 for optimizing the spatial arrangement of data constituting the three-dimensional image data based on the spatial position information.

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 for providing a three-dimensional image by scanning a three-dimensional region of a subject and a method for reconstructing three-dimensional image data. The present invention relates to an ultrasonic diagnosis focusing on the relationship between data necessary and sufficient to perform the calculation and a spatial position.

A typical example suitable for carrying out the present invention is a contrast echo method in which an ultrasonic contrast agent is administered to a subject and a tomographic image is obtained by using a reception signal including a reflected ultrasonic signal from the contrast agent. In particular, this is an embodiment in which the presence of microbubbles, which is a main component of the ultrasonic contrast agent, can be more effectively imaged, but the present invention is not necessarily limited to this.

[0003]

2. Description of the Related Art The medical application of ultrasonic signals covers various fields and is one of ultrasonic diagnostic apparatuses. An ultrasonic diagnostic apparatus is an apparatus that transmits and receives an ultrasonic signal to and from a subject to thereby obtain an image signal, and is used in various modes by utilizing the non-invasiveness of the ultrasonic signal. The mainstream of this ultrasonic diagnostic apparatus is of a type that obtains a tomographic image of a soft tissue of a living body using an ultrasonic pulse reflection method. This imaging method can obtain a tomographic image of a tissue in a non-invasive manner, using an X-ray diagnostic apparatus,
Compared to other medical modalities such as X-ray CT scanners, MRI equipment, and nuclear medicine diagnostic equipment, real-time display is possible, the equipment is small and relatively inexpensive, and there is no exposure to X-rays. It has many advantages, such as blood flow imaging.

[0004] For this reason, it is widely used in diagnosis of the heart, abdomen, mammary gland, urology, obstetrics and gynecology, and the like. In particular, the heartbeat and the movement of the fetus can be observed in real time by a simple operation of simply applying the ultrasonic probe to the body surface, and the examination can be repeated many times because there is no exposure. In addition, the apparatus has various advantages such that the apparatus can be moved to the bedside and the inspection can be easily performed there.

In the field of the ultrasonic diagnostic apparatus, recently, when an examination of the heart or abdominal organ is performed, an ultrasonic contrast agent (hereinafter referred to as a contrast agent) is injected from a vein to evaluate the blood flow dynamics. The contrast echo method to be performed is attracting attention. The method of injecting a contrast agent from a vein is less invasive than the arterial contrast echocardiography in which the contrast agent is injected from an artery, and diagnosis by this evaluation method is becoming widespread. The main component of the contrast agent is microbubbles, which are reflection sources that reflect ultrasonic signals. The higher the injection amount or the concentration of the contrast agent, the greater the contrast effect. However, due to the nature of the bubbles of the contrast agent, there are cases where the time of the contrast effect is shortened by ultrasonic irradiation. In view of such a situation, a persistent and pressure-resistant contrast agent has been developed in recent years, but there is a concern that a long stay of the contrast agent in the body may lead to an increase in invasiveness.

When the contrast echo method is performed, a contrast agent is supplied to a region of interest of a subject part by a blood flow one after another. For this reason, even if the bubbles are once erased by irradiating the ultrasonic waves, it is assumed that the contrast effect is maintained if new bubbles have flowed into the region of interest at the time of the next ultrasonic irradiation. However, in practice, the transmission and reception of ultrasonic waves are usually performed several thousand times per second, and given the existence of blood flow dynamics in organ parenchyma and relatively small blood vessels, which have a low blood flow velocity. On the diagnostic image of, the bubbles disappear one after another before confirming the brightness enhancement by the contrast agent, and the contrast effect is instantaneously reduced.

The contrast echo method can be more effectively implemented by a harmonic imaging method in which an image is formed using a non-fundamental wave component of an ultrasonic echo signal.
The harmonic imaging method is an imaging method that separates and detects only a non-fundamental wave component due to a non-linear behavior generated when a microbubble, which is a main component of a contrast agent, is excited by ultrasonic waves. Specifically, for example, when an ultrasonic signal is transmitted at a frequency of 2.5 MHz, a 5 MHz component is extracted and imaged from each component of the echo signal.
Since living organs are relatively unlikely to exhibit nonlinear behavior, 5M
The harmonic component of Hz is small, and the dynamics of the contrast agent can be observed as an image with a good contrast ratio.

As for the phenomenon in which microbubbles disappear due to the irradiation of ultrasonic waves as described above, the present inventors have published a research report in "67-95, Examination of Flash Echo Imaging Method (1)". , Naohisa Kamiyama et al., The 7th Annual Meeting of the Japanese Society of Ultrasound Medicine, 1996.6 ”, using flash echo imaging (or transientR).
It was reported that the brightness enhancement effect was improved by an imaging method called "esponse Imaging".
This imaging method, in principle, replaces the conventional continuous scan of several tens of frames per second with one per second.
In this method, intermittent transmission such as a frame is performed, and during the intermittent time, minute air bubbles that are densely packed without being broken are eliminated at once in the next transmission to obtain a high echo signal.

In parallel with the development of such various innovative imaging methods, CT has been
Like MRI and MRI, the need for three-dimensional imaging is rushing. Since the three-dimensional stereoscopic image includes information on the depth direction in addition to the two-dimensional tomographic image, it is possible to more clearly know the shape of the tissue and the running dynamics of the blood vessel.

A three-dimensional scan is performed on the subject,
Various methods for acquiring image data three-dimensionally are known. As one of the methods, a technique has been proposed in which a two-dimensional probe having oscillators arranged two-dimensionally captures three-dimensionally distributed echoes almost simultaneously.

As another scanning method, a method of relatively easily obtaining a three-dimensional image using a conventional probe having a one-dimensional array of transducers is also known. Specifically, 1
In this scan, a two-dimensional cross section is scanned while the two-dimensional probe is moved spatially little by little, and echo data and scan position information of the cross section are simultaneously captured and recorded. The position information is detected from a position sensor attached to the probe. After scanning a desired three-dimensional space in the subject, the recorded data is reconstructed by referring to the position information and displayed as a three-dimensional image. In particular, recent CP
With the increase in speed and function of U, the reconstruction and display of such a stereoscopic image can be performed in a very short time.

[0012]

As described above, the three-dimensional scanning method in which a one-dimensional array of probes is moved spatially to collect echo data is very simple, but also has the following problems. It is pointed out.

(1): In the case of such a three-dimensional scan, 1
Since three three-dimensional images are created by using a plurality of pieces of tomographic image data, generally, a memory having a much larger storage capacity than in the conventional two-dimensional scan is required.

(2) The three-dimensional scan can be applied to the above-described contrast echo method, harmonic imaging method, or flash echo imaging method with exactly the same procedure. However, since the probe is usually operated manually, it is difficult to move the probe at a completely moderate speed. Therefore, in consideration of the phenomenon of disappearance of bubbles of the contrast agent, the unevenness of the moving speed causes variations in the echo luminance, and it may not be possible to obtain a high-quality, high-definition three-dimensional image.

The present invention has been made in view of the above-mentioned problems of the prior art in which a one-dimensional probe is used to scan a three-dimensional area, and when the probe is manually moved for scanning, the moving speed is large, small, and uneven. Therefore, an ultrasonic diagnostic apparatus and a method for reconstructing a three-dimensional image that can collect three-dimensional image data in a state of a tomographic image with no waste taking into account the spatial position and provide the acquired three-dimensional image data for image reconstruction. Its purpose is to provide.

In addition, the present invention is particularly applicable to a case where the contrast echo method is carried out by scanning a three-dimensional area using a one-dimensional probe, in a state of a tomographic image in which a spatial position is taken into consideration and no waste is caused. It is another object to provide an ultrasonic diagnostic apparatus and a method for reconstructing a three-dimensional image that can collect echo data and reconstruct a three-dimensional image from the data.

[0017]

According to an ultrasonic diagnostic apparatus of the present invention, a three-dimensional region of a subject is scanned with an ultrasonic beam for each cross section to obtain an echo signal. Position information for detecting the spatial position information of each of the cross-sections when the three-dimensional area is scanned by the scanning means, comprising: scanning means for collecting; and data generating means for generating three-dimensional image data from the echo signal. It is characterized by comprising detecting means and optimizing means for optimizing a spatial arrangement of each data forming the three-dimensional image data based on the spatial position information.

Preferably, the scanning means has a one-dimensional probe which is manually movable along the body surface of the subject and is responsible for transmitting and receiving ultrasonic signals related to the ultrasonic beam.

Thus, when scanning a three-dimensional area with a one-dimensional probe, when the probe is manually moved and scanned, even if the moving speed is large or small, unevenness, etc., there is no waste taking into account the spatial position. It is possible to collect three-dimensional image data in the state of a tomographic image and to provide this for reconstruction.

Specifically, as an example, the optimizing means calculates a distance between a cross section of the cross section and a cross section before the cross section based on the spatial position information;
Adding means for adding the information of the distance to the image information of the certain section; determining means for determining whether to use the image information of the cross section as the three-dimensional image data based on the information of the distance; Providing means for providing only the image information determined to be adopted by the means to the spatial arrangement in the three-dimensional image data.

For example, there is provided a display means for displaying the distance information together with the image information of the section to which the distance information is added. Further, the distance information is a distance between the cross sections assuming that the cross sections are parallel, a moving distance of a point defined on each of the cross sections, or a moving distance of a base point of the probe with respect to each of the cross sections. .

In a preferred aspect, the determining means determines whether or not the distance information is equal to or greater than a predetermined threshold value, and the providing means determines whether or not the distance information is determined by the determining means. When it is determined that the distance information is equal to or greater than the threshold value, it is determined that the distance information is smaller than the threshold value by the means for providing the image information to the spatial arrangement in the three-dimensional image data and the determination means. Sometimes
Means for discarding the image information. An operator may arbitrarily specify the threshold value.

In another aspect, the ultrasonic diagnostic apparatus is an apparatus for performing a contrast echo method for performing a scan in a state where an ultrasonic contrast agent is administered to the subject,
The determining means determines whether or not the distance information is equal to or greater than a first threshold value; and the first determining means determines that the distance information is less than the first threshold value. Second determining means for determining again whether or not the distance information is equal to or greater than a second threshold value set to a value smaller than the first threshold value, wherein the providing means includes: Means for providing the image information of the section to which the distance information has been added to the spatial arrangement in the three-dimensional image data when the distance information is determined to be equal to or greater than the first threshold value. And when the second determination means determines that the distance information is equal to or greater than the second threshold value,
Means for correcting the image information of the section to which the distance information has been added and providing the corrected information to the spatial arrangement in the three-dimensional image data;
A means for discarding the image information of the section to which the distance information has been added, when the second determination means determines that the distance information is smaller than the second threshold value.

On the other hand, the optimizing means monitors the distance information between the section scanned last time and the section scanned at the current probe position based on the spatial position information, and the monitoring means. And an irradiation control unit for controlling an irradiation interval of each section of the ultrasonic pulse applied to the ultrasonic beam according to the distance information obtained by the above.

In this case, the ultrasonic diagnostic apparatus is an apparatus for performing a contrast echo method for performing a scan in a state where an ultrasonic contrast agent is administered to the subject, and the irradiation control means includes the distance vector information and the This is a means for controlling based on the waiting time from the previous irradiation of the ultrasonic pulse. For example, the waiting time may be set based on blood flow information flowing into a region of interest of an organ to be diagnosed, and a setting means capable of setting an optimum value according to the type of the organ may be provided.

Further, in the above-described various configurations, it is preferable that an image providing means for providing a tomographic image of the three-dimensional area or an image of blood flow information based on the echo signal is provided.

On the other hand, in the method of reconstructing three-dimensional image data according to the present invention, an echo signal is collected by scanning a three-dimensional region of a subject with an ultrasonic beam for each section, and three-dimensional image data is obtained from the echo signal. And detecting spatial position information of each of the cross sections when the three-dimensional region is scanned by the scanning, and based on the spatial position information, detects data of each data forming the three-dimensional image data. It is characterized in that the spatial arrangement is optimized.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described.
This will be described with reference to the drawings.

The present invention can be similarly applied not only to the contrast echo method in which a contrast agent is administered to a subject for scanning but also to an imaging method in which scanning is performed without administering a contrast agent. In particular, when the contrast echo method is performed, the present invention can be suitably applied to all the sites of interest when observing the blood flow dynamics based on the degree of contrast based on the contrast agent. Thus, as an example, in the present embodiment described below, blood flow dynamics are obtained from the degree of contrast of a contrast agent flowing into the liver parenchyma or heart muscle, an ultrasonic contrast agent is administered to a subject, and an abnormal site is determined. The identification method will be described.

[First Embodiment] FIG. 1 shows a first embodiment.
This will be described with reference to FIGS. The ultrasonic diagnostic apparatus according to this embodiment has a configuration in which an ultrasonic contrast agent is administered to a subject and the state of blood flow is observed from the degree of contrast.

FIG. 1 schematically shows the entire configuration of the ultrasonic diagnostic apparatus according to the first embodiment. The ultrasonic Doppler diagnostic apparatus shown in FIG. 1 includes an apparatus main body 11 and an ultrasonic probe (hereinafter, referred to as a probe) 1 connected to the apparatus main body 11.
2, an operation panel 13, an ECG (electrocardiograph) 14, and a position detector 15. The subject is indicated by the reference symbol P.

The operation panel 13 is provided with a keyboard 13A, a trackball 13B, etc., and gives various instructions and information from the operator to the apparatus main body 11 to set the apparatus conditions in the same manner as the conventional apparatus, and to display the ROI on the image. (Region of interest)
Is used to change the setting conditions according to the present invention.

The probe 12 is a device that transmits and receives an ultrasonic signal to and from the subject P, and has a piezoelectric vibrator such as a piezoelectric ceramic as an electro / mechanical reversible conversion element. As a preferred example, a plurality of piezoelectric vibrators are arranged in an array and mounted at the tip of the probe, and a phased array type probe 12 is configured. Thus, the probe 12 converts the pulse drive voltage supplied from the apparatus main body 11 into an ultrasonic pulse signal, transmits the ultrasonic pulse signal in a desired direction in the subject, and responds to the ultrasonic echo signal reflected from the subject. Convert to voltage echo signal.

As shown, the apparatus main body 11 has a probe 12
Unit 21 and receiving unit 2 connected to
2. A receiver unit 23 placed on the output side of the receiving unit 22, a B-mode DSC (digital scan converter) 24, an image memory circuit 25, a three-dimensional operation circuit 26, a Doppler unit 27, and a data synthesizer 2.
8 and a display 29.

The apparatus main body 11 has a coordinate memory 30 connected to the position detector 15 and the operation panel 13, and the coordinate memory 30 and the image memory circuit 25.
And a distance calculation circuit 31 interposed between them. Further, the apparatus main body 11 includes a heartbeat detection unit 32 that receives an ECG signal detected by the ECG 14. Further, the apparatus main body 11 receives operation information from the operation panel 13 and
A controller 33 that controls the operation and set values of each circuit of the apparatus main body 11 is provided.

The input side of the image memory circuit 25 is connected to the B-mode DSC 24, the Doppler unit 27, and the distance calculation circuit 31, and the output side is connected to the three-dimensional calculation circuit 26 and the data synthesizer 28.

The image memory circuit 25 stores the image data output by the B-mode DSC 24 and the DSC of the Doppler unit 27 in one or both of a raster signal sequence of an ultrasonic scan and a raster signal sequence of a video format. Memory. Therefore, the operator can call and use the image data after the diagnosis. In this case, the image data of the image memory circuit 25 is sent to the display 29 via the data synthesizer 28. The image data stored in this memory is
It is also used for reconstructing a three-dimensional image as described later.

The transmission / reception system of the apparatus main body 11 will be described.

The transmission unit 21 includes a pulse generator 21
A, a transmission delay circuit 21B, and a pulser 21C. The pulse generator 21A generates a rate pulse having a rate frequency fr [Hz] of 5 KHz (period 1 / fr [second]), for example. This rate pulse is distributed to the number of transmission channels and sent to the transmission delay circuit 21B. A timing signal for determining a delay time is supplied from the controller 33 to the transmission delay circuit 21B for each transmission channel. Thereby, the transmission delay circuit 21B gives a command delay time to the rate pulse for each channel. The rate pulse provided with the delay time is supplied to the pulser 21C for each transmission channel. The pulser 21C gives a voltage pulse to each piezoelectric vibrator (transmission channel) of the probe 12 at the timing of receiving the rate pulse. This allows
An ultrasonic signal is emitted from the probe 12. The ultrasonic signal transmitted from the ultrasonic probe 12 is focused in a beam shape in the subject, and the transmission directivity is set in the command scanning direction. The time interval of the scan performed by the transmission unit 21 is controlled by the controller 33 to a predetermined time value.

In the subject, beamforming is performed according to the above-described delay time. The transmitted ultrasonic pulse signal is reflected by a discontinuous surface of acoustic impedance in the subject. This reflected ultrasonic signal is transmitted to the probe 12 again.
And is converted into an echo signal of a corresponding voltage amount. This echo signal is taken into the receiving unit 22 from the probe 12 for each receiving channel.

The receiving unit 22 includes a preamplifier 22A, a receiving delay circuit 22B, and an adder 22C in order from the input side. Each of the preamplifier 22A and the reception delay circuit 22B has a built-in amplifier circuit or delay circuit for the number of reception channels. The delay time of the reception delay circuit 22B is provided from the controller 33 as a signal of a delay time pattern according to a desired reception directivity. Therefore, the echo signal is amplified by the preamplifier 22A for each reception channel, given a delay time by the reception delay circuit 22B, and then added by the adder 22C. By this addition, the reflection component from the direction corresponding to the desired reception directivity is emphasized. An overall ultrasonic beam for transmission and reception is formed by integrating the transmission directivity and the reception directivity.

The output end of the adder of the receiving unit 22 reaches the data combiner 28 via the receiver unit 23 and the B-mode DSC 24 in order.

The receiver unit 23 is not shown, but
A logarithmic amplifier, an envelope detector, and an A / D converter are provided. In the case of a device that performs the harmonic imaging method, the receiver unit 27 is equipped with a band-pass filter that allows only a high-frequency component, for example, twice the transmission frequency of the ultrasonic signal to pass. With this receiver unit, echo data in the direction given the reception directivity is formed in a digital amount and sent to the B-mode DSC 24.

The B-mode DSC 24 converts echo data from a raster signal sequence of an ultrasonic scan into a raster signal sequence of a video format, and sends this to a data synthesizer 28. This image data is also sent to the image memory circuit 25 and stored in the state of the signal sequence of the ultrasonic scan and the signal sequence of the video format.

The Doppler unit 27 receives the added echo signal from the receiver unit 23. Although not shown, the unit 27 includes a quadrature detector, a clutter removing filter, a Doppler shift frequency analyzer, an arithmetic unit such as an average speed, a DSC, a color processing circuit, and the like. And its power information are obtained as color flow image data. This color flow image data (CFM data) is
Receives a process such as noise cancellation by a built-in DSC, and converts its scanning method into a data synthesizer 2.
8 The color flow image data is also sent to and stored in the image memory circuit 25.

On the other hand, the position detector 15 is, for example, a magnetic sensor that is mechanically attached to the probe 12 or that has only a detection unit directly attached to the probe 12.
Thus, spatial position information of the probe 12 can be detected.

In the present embodiment, as shown in FIGS. 2A and 2B, a three-dimensional scanning method in which the probe 12 is manually moved along the body surface of the subject P is adopted. During this movement, a cross section corresponding to each position on the body surface is scanned at regular time intervals in a three-dimensional region in the body, and echo signals from each voxel position constituting the cross section are collected. You. Therefore, the three-dimensional region is scanned with the movement of the cross section to be two-dimensionally scanned, and the three-dimensional scan is achieved.

FIG. 6B shows the fixed times t1, t2,
, Two-dimensional scan sections S1, S2, ..., Si for each ti
And the distances d2, d3,..., Di-1, di between the cross sections
Are illustrated.

That is, as a general expression, FIG.
Thus, the Z axis of the rectangular coordinate system is set in the body axis direction of the subject P.
And the X axis and the Y axis are set in the horizontal direction and the front-back direction of the subject P.
The probe 12 along the body surface of the subject.
While moving the probe 12 around the X axis.
The rotation direction α, the rotation direction β around the Y axis, and the Z axis
By operating in the rotation direction γ about the center, three-dimensional scanning
It can be said that a fortune is performed. In addition, two-dimensional operation is performed
The position of the probe 12 at the time of₀(X ₀, Y
₀, Z₀).

Therefore, the position detector 15 is connected to the probe 1
2 reference position P₀(X₀, Y₀, Z ₀), Angle θ_α(X
Rotation angle about the axis), angle θ_β(Around the Y axis
Rotation angle), and angle θ_γ(Rotation around the Z axis
Angle), and a signal (positional information) corresponding to the detected value is detected.
) Is output to the coordinate memory 30 of the apparatus main body 11.

The coordinate memory 30 stores position information detected by the position detector 15 and operation information from the operation panel circuit 21.

The distance calculation circuit 31 reads out the position information stored in the coordinate memory 30, calculates the information indicating the state of approach between the tomographic images when scanning while moving the probe 12, and also uses this information. The included position information is written to the image memory circuit 25 so as to be added to the image data Si in the circuit 25.

More specifically, when the planes of the tomographic images are parallel to each other, the information representing such an approach state may be a distance di between two planes described mathematically (see FIG. 2B) or Assuming that the rotation angle of the probe 12 can be ignored, any one of the movement distances di is calculated by the distance calculation circuit 31 from the probe position (x, y, z).

However, when the planes of the tomographic images are not parallel to each other, another definition of “distance” is required. Since the purpose of the distance calculation is to eliminate redundant image data, the distance d
i may be determined as follows, for example. A reference point may be provided in the tomographic image, and the distance di between the tomographic image Si-1 and the reference point of Si may be calculated. As the reference point, various positions such as “a position at a depth of 6 cm on the central scanning line”, “a position corresponding to the focus depth on the central scanning line”, and “an arbitrary position designated by the operator” may be employed. Can be.

As a result, since the image data Si scanned from the B-mode DSC 24 and / or the Doppler unit 27 at regular time intervals ti is stored in the memory of the image memory circuit 25, this image data Si and its image are stored. The information di of the position at which the data was collected is uniquely associated.

The associated image data Si and position information di are read out to the next-stage three-dimensional arithmetic circuit 26 at the stage when the scanning of the two sections has been completed. The read data is subjected to data discrimination processing based on the distance di between adjacent cross sections, and only necessary data is taken into the circuit 26. A specific example of the operation of the three-dimensional operation circuit 26 will be described later with reference to FIG.

The image data Si captured by the three-dimensional arithmetic circuit 26 is based on the position information of each imaging section and the swing angle of the scanning line. It is arranged in space and reconstructed into volume data according to the real space. In addition, this 3
The dimension calculation circuit 26 creates image data projected onto a two-dimensional cross section such as a bird's-eye view or a perspective view from the reconstructed three-dimensional image data. This image data is sent to the data synthesizer 28.

On the other hand, the ECG 14 is used mainly in contact with the body surface of the subject P to obtain electrocardiographic waveform data of the subject. This data is input to a heartbeat detection unit, which will be described later, and intermittent transmission of ultrasonic waves triggered by an electrocardiogram is performed.

The heartbeat detection unit 32 inputs the ECG signal supplied from the ECG 14 and sends out the electrocardiographic waveform data to the data synthesizer 28 for display, while synchronizing the heart image with the electrocardiographic waveform, so-called. A trigger signal for synchronizing the electrocardiogram is created, and the trigger signal is sent to the pulse generator 21A of the ultrasonic transmission unit 21.

As described above, the data synthesizer 28 includes the B mode image data (gray scale image) sent from the B mode DSC 24, the CFM mode image data (color flow image) sent from the Doppler unit 27, ECG waveform data sent from the detection unit 32,
The operation data of the three-dimensional operation circuit 26 and / or desired setting parameters are arranged or overlapped to reconstruct image data of one frame. CFM
The mode image data is converted into B
The image is synthesized in a form superimposed on the mode image data. The frame image data is sequentially read out by the display 29.

The display 29 has a built-in D / A
The data is converted into an analog amount by a converter and displayed on a display such as a TV monitor as a tomographic image of the subject.

Further, the controller 33 includes an A / D converter for receiving operation data from the operation panel 13 and a CP.
A memory connected to the CPU is provided in addition to the U (central processing unit). The CPU is connected to the operation panel 13, the transmission unit 21, the reception unit 22, and other units and circuits not shown via an interface,
Perform those controls and parameter settings.

The overall operation of the ultrasonic diagnostic apparatus according to this embodiment will be described.

At the time of scanning, as an example, the probe 12 is moved in parallel along the body surface of the subject P as shown in FIG. Thereby, echo signals are collected from the tomographic images S1, S2,..., Sn as shown in FIG. When the operator manually moves the probe 12, the distance di between the tomographic images S1, S2,.
Can vary. The tomographic images S1, S2, ...,
The echo data of Sn is obtained at times t1 and t for each predetermined time Δt.
, Tn, variations in the probe moving speed appear as variations in the distance d between tomographic images.
In FIG. 3B, the distance between the tomographic images S1 and S2 is d2, the distance between the tomographic images S2 and S3 is d3, and the distance between the tomographic images Si-1 and Si is di. When expressed in such a manner, the value of the distance di changes.

Therefore, the three-dimensional arithmetic circuit 26 executes the processing shown in FIG. 4 to execute reconstruction of the three-dimensional image data and two-dimensional projection while eliminating the inconvenience relating to the variation of the distance di during the three-dimensional scan. I do.

The three-dimensional arithmetic circuit 26 reads the threshold value D set in advance for the distance d, or sets an arbitrary value from the operation panel 13 each time the operator sets the threshold value. D is set (step S1). This threshold value D is set to discriminate a distance d that is shorter than necessary between tomographic images during three-dimensional scanning. As will be described later, the image data of the tomographic image whose distance d is too close to the adjacent tomographic image is discarded and excluded from the data of the three-dimensional arrangement and the data of the two-dimensional projection.

Next, the three-dimensional arithmetic circuit 26 reads out the image data Si and the distance di of the tomographic image collected at a certain time t (step S2), and judges whether or not it is di (D) (step S3). When the determination is NO, that is, when the relationship of di <D is satisfied, it is determined whether correction data is created and used for the read image data Si (step S4). The step of determining whether or not to do
Either "correct" or "do not correct" may be set in advance, or each time "correct" or "do not correct" by referring to the operation information of the operator.
May be set.

When the determination in step S4 is YES, that is, when the image data Si is to be corrected, the three-dimensional arithmetic circuit 26 then sets another appropriately determined threshold value D1.
For (0 <D1 <D), it is determined whether or not D1 (di is satisfied (step S5). When this determination is YES, that is, when D1 (di is satisfied), predetermined correction of the image data Si is performed. (Step S6).

On the other hand, if the determination in step S5 is NO, that is, if di <D1, the image data Si and the distance di that have been read into the work area are discarded from the storage area (step S7). When NO is determined in step S4, that is, when the image data correction process is not performed, and when the distance di is smaller than the threshold value D, the process proceeds to step S7 to remove unnecessary data. Discarded.

The three-dimensional arithmetic circuit 26 determines whether the image data Si having undergone the correction processing in step S6 or the image data Si determined to have a sufficient distance di between the slices in step S3 (distance di (D)) , The image data Si is arranged in the three-dimensional memory space based on the position information di.

Next, after completing the three-dimensional data arrangement processing in step S8 or the data discarding processing in step S7, the flow advances to step S9 to determine whether the above-described series of processing has been completed for all tomographic image data. Judge. If the determination is NO, there is image data of the remaining tomographic image, so the flow returns to step S2 to repeat the above-described processing.

Conversely, if the determination in step S9 is YES
, Projection processing of the arranged three-dimensional data onto a two-dimensional plane is performed (step S10). Thereafter, the projected two-dimensional image data is output to the data synthesizer 28 (step S11), and the display 29 displays the image data in an appropriate mode.

As described above, the distance di from the previous tomographic image is added to the image data Si of the current tomographic image, stored together with the position information of the image data Si, and the data is adopted based on the distance di. Or discard it. This allows
If the current tomographic image is spatially closer to the previous tomographic image than is necessary, only redundant data will be obtained during three-dimensional reconstruction. Destroyed.

For this reason, even if the operator slows down the moving speed of the probe while moving the probe in parallel or inadvertently stops the probe and then moves the probe again, the redundancy during the period in which the speed is slowed down is maintained. No image data or image data during the period when the probe movement is stopped is not recorded in the image memory circuit 25.

Therefore, the memory area of the image memory circuit 25 is not wastefully occupied, so that the storage area can be reduced. Also, due to such data discard,
The amount of calculation for reconstruction is reduced.

The information on the distance d between tomographic images can be used not only for discrimination processing but also more effectively. For example, when the three-dimensional arithmetic circuit 26 wants to display a tomographic image before reconstructing the three-dimensional image data, the value of the distance di can be displayed together with the information on the image data of the tomographic image. In this process, the controller 33, which has received a command from the operation panel 13, transmits the command to the three-dimensional calculation circuit 26. The calculation circuit 26 reads out the image data Si of the tomographic image and the distance di in accordance with the command, and outputs the data. This is achieved by sending to the synthesizer 28.

The ultrasonic diagnostic apparatus according to the first embodiment can be suitably used by a contrast echo method as one of its uses. Hereinafter, this usage will be described.

The contrast echo method is performed by administering a contrast agent to a subject, and it is known that microbubbles, which are the main components of the contrast agent, are easily broken by irradiation with ultrasonic waves. ing. Therefore, the flash echo method is intended to improve the inconvenience caused by this collapse. After the microbubbles on the scan surface (slice) are collapsed, transmission is performed after the microbubbles are filled on the surface again, so-called intermittent transmission. Method is used.

When the probe 12 is moved by the three-dimensional scanning method according to the present invention, the collapse of microbubbles is
A situation as shown in FIG. 5 occurs. FIG (a) is a schematic diagram for irradiating an ultrasonic beam 52 when the microbubbles MB slice (scan plane) filling the SL _1. The intensity of the echo signal obtained at this time is I _0. Sign VS
Denotes a blood vessel, and TS denotes a living tissue.

FIG. 13B shows the state after the irradiation shown in FIG.
SL by the next irradiation performed in ₂Is the previous slice
SL₁Shows ultrasonic irradiation in a partially overlapping state.
This is due to the short time interval between exposures (high frame rates).
Occurs when the probe 12 moves slowly.
State. The intensity of the echo signal is slice SL₂Included in
(B) in FIG.
The intensity of the echo signal generated in the illumination state of
In other words, the intensity I described above₀About 1/4 of
You.

On the contrary, FIG. 11C shows a state where the slice SL ₂ ′ at the time of the next ultrasonic irradiation is sufficiently separated from the previous slice SL ₁ . At this time, slice S
Since the microbubbles MB are sufficiently present in L ₂ ′, the intensity of the echo signal is considered to be I ₀ as in the case of FIG.

That is, when the contrast echo method is performed, if the spatial distance between the slices is too short, not only is the data redundant, but also the signal intensity is low when reconstructing the three-dimensional echo data. Variations also occur.

However, if the contrast echo method is performed by the ultrasonic diagnostic apparatus of the first embodiment,
Such variations in redundant data (signal) and signal strength can be eliminated.

Specifically, the distance threshold value D
Is set to a value that does not overlap slices. Threshold D
Depends on the slice thickness of the converged ultrasonic beam, so based on the type of probe, scan mode, transmission frequency, number of transmission drive elements, setting conditions such as focus point,
An appropriate value that can eliminate the overlapping state of slices is set.
For example, the lower the transmission frequency, the larger the threshold value D; the larger the number of transmission drive elements, the larger the threshold value D; the closer the focus point, the larger the threshold value D. Alternatively, this threshold value D is used as blood flow velocity information depending on a diagnosis site (for example, a blood flow velocity is high in a heart chamber; a blood flow velocity is relatively high in a kidney; a blood flow velocity in a liver). Is slower, etc.). Of course, the operator may set the threshold value D to an arbitrary value.

As described above, by setting the threshold value D to an appropriate value for three-dimensional scanning based on the contrast echo method, the above-described processing of steps S3 and S7 in FIG. 4 effectively works. Even when the speed at which the probe 12 is moved is slow and part or all of the preceding and following slices overlap each other, the echo data collected in such a situation is subjected to discrimination processing and automatically discarded. You.
Therefore, such redundant data has nothing to do with the reconstruction of the three-dimensional data and does not wastefully occupy the memory area.

The processing in steps S4 to S6 in FIG. 4 works effectively. 3 performed under the contrast echo method
Even if there is data considered to be redundant in the collected data of the dimensional scan, this can be corrected and used. To explain this, when a medium containing a contrast agent is scanned, the relationship between the distance to the previous slice (scanned section) and the obtained echo signal intensity is qualitatively
It is represented as shown in FIG. Here, the critical point at which the intensity of the echo signal becomes constant corresponds to the above-described threshold. This has been reported by the present inventor as "Examination of flash echo imaging method (3) ... Relation between scan section and timing: Japanese Society of Ultrasound Medicine Research Presentation: 68-155, 1996, January 1"
January ".

Therefore, the distance di between slices is 0 <D1
When the condition of <di <D is satisfied, a process of correcting the intensity curve shown in FIG. 6 is performed on the image data Si of the tomographic image to which the distance di is attached (FIG. 4, step S5,
S6). This correction processing is luminance correction, and curve data shown in FIG. 7 that can compensate for the curve in FIG. 6 is obtained in advance.
This is performed by adding the compensation data. As a result, an echo image with uniform intensity (brightness) can be obtained in which the influence of the number of bubbles caused by the overlap of the ultrasonic beams is corrected.

When the distance di is discriminated in the correction processing, the lower limit value D1 is determined. This lower limit D1 is 0
The above values are set to appropriate values. Therefore, the probe 12
The echo data collected in a state where the movement has stopped completely is discriminated into redundant categories and discarded from the memory (FIG. 4, steps S5 and S7). Thereby, the data of the tomographic image exhibiting the distance di equal to or less than the threshold value D can be corrected and used for three-dimensional image reconstruction.

The advantages of the above configuration can be summarized as follows. First, it is possible to construct a three-dimensional image by automatically discarding (erasing) data from substantially the same cross section where echo data overlaps. Second, redundant echo data can be discarded from the memory of the image memory circuit 25, and the memory can be used effectively. Third, when the contrast echo method is performed, scanning is not performed on a cross section after the microbubbles of the contrast agent have disappeared, and scanning is always performed on a cross section where the contrast agent is present, and three-dimensional scanning is performed. Build images. This makes it possible to reliably obtain an image in which the properties of the contrast agent are sufficiently exhibited. Fourth, it is possible to correct the echo brightness affected by the disappearance of bubbles by the previous ultrasonic irradiation, use the collected echo data as much as possible, and increase the efficiency of data collection.

(Second Embodiment) Next, an ultrasonic diagnostic apparatus according to a second embodiment of the present invention will be described with reference to FIG. Here, the same reference numerals are used for the same or equivalent components as those of the device of the above-described first embodiment, and the description is omitted or simplified.

The ultrasonic diagnostic apparatus is characterized in that the distance between sections to be scanned is predicted and determined in advance, and the ultrasonic irradiation is performed based on the result of the determination.

In order to realize this feature, a distance determination circuit 41 and a timing generator 42 are added to the apparatus main body 11 of the ultrasonic diagnostic apparatus as shown in FIG. The distance determination circuit 41 is a circuit that reads out position information from the coordinate memory 30 and monitors the position information in real time. As described above, the position information of the probe 12 detected by the position detector 15 is written in the coordinate memory 30 in real time.

The distance determination circuit 41 is based on the distance information from the coordinate memory 30. More specifically, the current cross section Si + 1 predicted from the previous cross section Si and the current probe position.
Is estimated. Still at this stage,
No scan irradiation was performed this time. Note that this distance is the same as in the first embodiment.

Next, the distance determination circuit 41 performs a numerical comparison as to whether or not the estimated distance di + 1 is larger than the threshold value D. As a result, when the condition of di + 1> D is satisfied, a signal S1 notifying the condition is output to the timing generator 42.
Send to

The timing generator 42 also receives the detection signal S2 of the heartbeat detection unit 32 described above. The timing generator 42 monitors whether the AND condition of both signals S1 and S2 is satisfied, and sends the timing signal S3 to the pulse generator 21A of the transmission unit 21 when the AND condition is satisfied. Has become. The pulse generator 21A generates a pulse signal for transmission trigger toward the transmission delay circuit 21B only when receiving the timing signal S3.

As a result, in the case where ultrasonic transmission / reception is performed only in a phase having a heartbeat using the ECG signal, a state where the arrival of the heartbeat phase and the distance of the scan section are sufficiently secured has been established. Only when is the probe 12 driven by the transmission unit 21. As a result, transmission and reception of the ultrasonic pulse are performed.

As described above, according to the second embodiment, the position where the probe moves can be grasped in real time while the probe 12 is moving, and the distance information between the scan sections can be estimated and determined. Therefore, echo data can be collected only when the distance between the scan sections becomes an appropriate interval equal to or larger than the threshold value D. Conversely, there is no need to perform useless transmission and reception, and if the collected data is discarded after transmission and reception as in the first embodiment, there is no need to perform post-processing. As a result, the calculation load of the three-dimensional calculation circuit 26 is reduced, and a three-dimensional image can always be reconstructed from the optimum number of tomographic image data.

In the present embodiment, when no ECG signal system device is mounted, the timing generator 42 responds only to the signal S1 indicating that a sufficient distance has been secured between the scan sections in response to the timing signal. S3 may be generated.

The second embodiment also has a particularly remarkable effect when the contrast echo method is performed.
As already described in the first embodiment, when the contrast echo method is performed, if the current irradiation section is not more than the distance D corresponding to the ultrasonic beam thickness than the previous irradiation cross section, FIG. As described, the intensity of the echo signal from the contrast agent is reduced. However, according to the ultrasonic diagnostic apparatus of the present embodiment, the distance d between the previous irradiation section and the irradiation section predicted from the current probe position is monitored in real time, and the distance d sets the threshold D. An ultrasonic pulse is transmitted immediately upon exceeding. This ensures that
An area where a sufficient amount of the contrast agent exists can be reliably irradiated. Therefore, it is possible to obtain a tomographic image having almost the same luminance and provide a three-dimensional contrast image without luminance unevenness.

Further, the ultrasonic diagnostic apparatus according to the second embodiment can be modified in the following manner in consideration of blood flow information flowing into a region of interest. According to the study results of the flash echo method, even if the probe is fixed,
It has been elucidated that a clear contrast echo can be obtained by re-irradiating the organ after waiting for the flow of new blood (contrast agent). This waiting time is about 5 to 10 seconds including the detection of the perfusion of the micro blood flow. In relatively large vasculature this waiting time can be short.

Therefore, in the above-described second embodiment in which only the value of the distance d is monitored, the CPU that executes the algorithm considering the waiting time in the timing generator 42 is used.
And the like. An example of this algorithm is as follows. As the distance d, the threshold value D of the distance, the time t, and the preset waiting time T0 (the waiting time from the previous irradiation of the cross section),

[Outside 1] What should be done is as follows.

As a result, even when the moving speed of the probe 12 is very low, for example, the ultrasonic irradiation is performed after a certain period of time, and a good echo is obtained.

The operation panel 13 can be used as setting means for determining based on the information of blood flow flowing into the region of interest of the organ to be diagnosed and setting an optimum waiting time according to the type of the organ. .

The above-described embodiments and their modifications are merely examples, and are not intended to limit the scope of the present invention. The scope of the present invention is determined according to the description of the claims, and various types of ultrasonic diagnostic apparatuses can be implemented without departing from the scope of the present invention.

[0105]

As described above, according to the present invention, the spatial position information of each cross section when scanning a three-dimensional region of a subject is detected, and a three-dimensional image is detected based on the spatial position information. Since the spatial arrangement of each data forming data is optimized, spatially redundant data is eliminated and ultrasonic echo data at a necessary and sufficient spatial distance interval can be reliably collected. Can be rebuilt. As a result, it is possible to reduce the storage capacity and calculation load required for the memory.

Particularly, in the contrast echo method,
It is possible to selectively irradiate a region filled with bubbles of the contrast agent, and tomographic image data with high echo intensity can be obtained. Also,
In all tomographic images, the echo luminance due to the contrast agent can be uniformly acquired regardless of the moving speed of the probe.

[Brief description of the drawings]

FIG. 1 is a block diagram of an ultrasonic diagnostic apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a change over time in each cross-sectional position when performing a three-dimensional scan while manually moving a probe.

FIG. 3 is a conceptual diagram of three-dimensional scanning.

FIG. 4 is a flowchart illustrating an outline of processing of a three-dimensional operation circuit according to the first embodiment.

FIG. 5 is a view for explaining the relationship between the moving distance of a probe and the concentration of an ultrasonic contrast agent when performing a contrast echo method.

FIG. 6 is a diagram qualitatively illustrating a relationship between a distance and an echo intensity when the contrast echo method is performed.

FIG. 7 is a diagram qualitatively illustrating a relationship between a distance and an echo intensity correction amount when a contrast echo method is performed.

FIG. 8 is a block diagram of an ultrasonic diagnostic apparatus according to a second embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 11 apparatus main body 12 ultrasonic probe 13 operation panel 14 ECG 15 position detector 21 transmission unit 22 reception unit 23 receiver unit 24 B-mode DSC 25 image memory circuit 26 three-dimensional operation circuit 27 Doppler unit 28 data synthesizer 29 display 30 coordinates Memory 31 Distance calculation circuit 32 Heart rate detection unit 33 Controller 41 Distance judgment circuit 42 Timing generator

Claims (13)

[Claims] A scanning unit configured to scan a three-dimensional region of an object with an ultrasonic beam for each cross section to collect an echo signal; and a data generating unit configured to generate three-dimensional image data from the echo signal. In the ultrasonic diagnostic apparatus, a position information detecting unit that detects spatial position information of each of the cross sections when the three-dimensional region is scanned by the scanning unit, and forms the three-dimensional image data based on the spatial position information Optimizing means for optimizing the spatial arrangement of data to be processed. 2. The ultrasonic diagnostic apparatus according to claim 1, wherein the scanning unit is capable of manually moving along the body surface of the subject and transmitting and receiving an ultrasonic signal related to the ultrasonic beam. An ultrasonic diagnostic apparatus having a one-dimensional probe to carry. 3. The ultrasonic diagnostic apparatus according to claim 2, wherein the optimizing means calculates a distance between a cross section of the cross section and a cross section before the cross section based on the spatial position information. Means for adding the information of the distance to the image information of the certain cross section, and judging means for judging whether or not to adopt the image information of the cross section as the three-dimensional image data based on the information of the distance. Providing means for providing only the image information determined to be adopted by the determining means to the spatial arrangement in the three-dimensional image data. 4. The ultrasonic diagnostic apparatus according to claim 3, further comprising display means for displaying the distance information together with image information of the cross section to which the distance information has been added. . 5. The ultrasonic diagnostic apparatus according to claim 3, wherein the distance information is a distance between sections when the sections are assumed to be parallel, and a moving distance of a point defined on each section. Or a moving distance of a base point of each of the cross sections of the probe. 6. The ultrasonic diagnostic apparatus according to claim 3, wherein said determining means is means for determining whether said distance information is equal to or greater than a predetermined threshold value, and said providing means is said determining means. Means for providing the image information to the spatial arrangement in the three-dimensional image data when it is determined that the distance information is equal to or greater than the threshold value; Means for discarding the image information when it is determined to be smaller than the above. 7. The ultrasonic diagnostic apparatus according to claim 6, further comprising designation means for allowing an operator to arbitrarily designate the threshold value. 8. The ultrasonic diagnostic apparatus according to claim 3, wherein the ultrasonic diagnostic apparatus performs a contrast echo method of performing a scan in a state where an ultrasonic contrast agent is administered to the subject. Determining means for determining whether or not the distance information is equal to or greater than a first threshold; and determining whether the distance information is less than the first threshold by the first determining means. Second determining means for determining again whether or not the information is equal to or greater than a second threshold value set to a value smaller than the first threshold value, wherein the providing means comprises: When the determining means determines that the distance information is equal to or larger than the first threshold value, the image information of the section to which the distance information is added is converted to the 3rd image.
Means for providing spatial arrangement to the two-dimensional image data; and when the second determination means determines that the distance information is greater than or equal to the second threshold value, a section of the section to which the distance information is added Means for correcting the image information and providing the spatial arrangement to the three-dimensional image data; and when the distance information is determined to be smaller than the second threshold value by the second determination means, Means for discarding the image information of the section to which the information has been added. 9. The ultrasonic diagnostic apparatus according to claim 1, wherein the optimizing unit determines a distance between a cross section scanned last time based on the spatial position information and a cross section scanned at the current probe position. Monitoring means for monitoring the distance information; and irradiation control means for controlling an irradiation interval for each section of the ultrasonic pulse applied to the ultrasonic beam according to the distance information obtained by the monitoring means. Ultrasound diagnostic equipment. 10. The ultrasonic diagnostic apparatus according to claim 9, wherein the ultrasonic diagnostic apparatus performs a contrast echo method for performing a scan in a state where an ultrasonic contrast agent is administered to the subject. An ultrasonic diagnostic apparatus, wherein the irradiation control means is means for controlling based on the distance vector information and a waiting time from the previous irradiation of the ultrasonic pulse. 11. The ultrasonic diagnostic apparatus according to claim 10, wherein the waiting time is determined based on blood flow information flowing into a region of interest of an organ to be diagnosed, and an optimum value is determined according to the type of the organ. An ultrasonic diagnostic apparatus including setting means that can be set. 12. The ultrasonic diagnostic apparatus according to claim 1, further comprising: an image providing unit that provides a tomographic image of the three-dimensional region or an image of blood flow information based on the echo signal. An ultrasonic diagnostic apparatus characterized in that: 13. A three-dimensional image data reconstruction method for scanning a three-dimensional region of a subject with an ultrasonic beam for each section to collect echo signals and generating three-dimensional image data from the echo signals. Detecting spatial position information of each of the cross sections when scanning the three-dimensional region by scanning, and optimizing a spatial arrangement of data forming the three-dimensional image data based on the spatial position information; A reconstruction method characterized by the following.