WO2017126209A1

WO2017126209A1 - Ultrasonic diagnostic device and sound velocity quantification method

Info

Publication number: WO2017126209A1
Application number: PCT/JP2016/084124
Authority: WO
Inventors: 拓明山本
Original assignee: 富士フイルム株式会社
Priority date: 2016-01-22
Filing date: 2016-11-17
Publication date: 2017-07-27

Abstract

This ultrasonic diagnostic device transmits an ultrasonic beam to a subject from an array transducer in which a plurality of first elements are arranged, and receives an ultrasonic echo from the subject to perform ultrasonic diagnosis. The ultrasonic diagnostic device is provided with: an element data memory (7) which stores a plurality of element data which are output from the plurality of first elements that received an ultrasonic echo reflected by a reflection point in the subject as a result of transmission of an ultrasonic beam to the reflection point; a time difference calculation unit (21) which calculates a plurality of time differences between element data corresponding to a reference element which is one of the plurality of first elements and a plurality of element data corresponding to a plurality of measurement elements which are elements other than the reference element of the plurality of first elements; a sound velocity calculation unit (22) which calculates a plurality of individual sound velocities corresponding to the plurality of measurement elements on the basis of the distance from the reflection point to the reference element, the distances from the reflection point to the plurality of measurement elements, and the plurality of time differences calculated by the time difference calculation unit (21); and an overall sound velocity determination unit (23) which determines the overall sound velocity on the basis of the individual sound velocities calculated by the sound velocity calculation unit (22).

Description

Ultrasonic diagnostic apparatus and sound speed quantification method

The present invention relates to an ultrasonic diagnostic apparatus and a sound velocity quantification method, and more particularly, to sound velocity quantification in a region between an array transducer and an ultrasonic beam reflection point.

Conventionally, in the medical field, an ultrasonic diagnostic apparatus using an ultrasonic image has been put into practical use. In general, in this type of ultrasonic diagnostic apparatus, an ultrasonic beam is transmitted from an array transducer in which a plurality of elements are arranged into the subject, and ultrasonic echoes from the subject are received by the array transducer, and element data is received. And an elemental data is electrically processed by the apparatus body to generate an ultrasonic image.

In such an ultrasonic diagnostic apparatus, when an ultrasonic beam is transmitted for the purpose of improving the azimuth resolution of the ultrasonic image, the ultrasonic beam is transmitted from each element of the array transducer by focusing on each scanning line. When the transmission focus is performed and the ultrasonic echo is received, the reception focus for aligning the time phases of the element data according to the arrangement position of each element of the array transducer is performed.
These transmission focus and reception focus are performed using the sound velocity of the propagation medium of the ultrasonic beam, but it is necessary to estimate the sound velocity in the subject that is the propagation medium.

For example, in the ultrasonic diagnostic apparatus disclosed in Patent Document 1, a plurality of received signals obtained from a plurality of elements of an array transducer are used, and a plurality of evaluation frames are formed corresponding to a plurality of sound speed candidates, A sound speed candidate that maximizes the intensity of the signal obtained by the phasing addition processing in the evaluation frame is used as an optimum sound speed estimation value.

JP2015-62483A

However, in the apparatus of Patent Document 1, phasing addition processing is performed by applying a uniform sound speed candidate to a received signal acquired by a plurality of elements of an array transducer. When the region between the reflection points has a uniform sound velocity, the optimum sound velocity value can be estimated, but the sound velocity in the region between the plurality of elements and the reflection point in the subject is uniform. Otherwise, there is a problem that the accuracy of sound speed estimation is lowered.
In particular, the speed of sound is often different in a lesion area compared to other regions, and if a lesion area exists between multiple elements of an array transducer and a reflection point in a subject, the sound speed is accurately estimated. Will become difficult.

The present invention has been made to solve such a conventional problem. Even when the sound speed in the region between the plurality of elements of the array transducer and the reflection point is not uniform, the sound speed can be accurately obtained. An object of the present invention is to provide an ultrasonic diagnostic apparatus and a sound speed quantification method that can be quantified.

The ultrasonic diagnostic apparatus according to the present invention transmits an ultrasonic beam from an array transducer in which a plurality of first elements are arranged toward a subject, receives an ultrasonic echo from the subject, and performs ultrasonic diagnosis In the ultrasonic diagnostic apparatus, a plurality of outputs output from a plurality of first elements that receive an ultrasonic echo reflected by a reflection point in response to transmission of an ultrasonic beam toward the reflection point in the subject An element data memory for storing element data; element data corresponding to a reference element that is one of the first plurality of elements; and a plurality of elements other than the reference element among the first plurality of elements A time difference calculator that calculates a plurality of time differences between a plurality of element data corresponding to a plurality of measurement elements, a distance from a reflection point to a reference element, and a distance from the reflection point to a plurality of measurement elements Distance and time difference A sound speed calculation unit that calculates a plurality of individual sound speeds corresponding to a plurality of measurement elements based on a plurality of time differences calculated by the output unit, and an overall sound speed based on the plurality of individual sound speeds calculated by the sound speed calculation unit And an overall sound speed determining unit.

In the plurality of individual sound speeds calculated by the sound speed calculation unit, it is determined whether or not there is an individual sound speed in which the absolute value of the difference from the overall sound speed determined by the overall sound speed determination unit exceeds the speed threshold, It is preferable to provide an outlier specifying unit that specifies an area between an element corresponding to an individual sound speed at which the absolute value of the difference exceeds the speed threshold and the reflection point as an outlier.
Also, calculated by the sound velocity calculation unit based on the distance to two or more elements that have received ultrasonic echoes that pass through the out-of-reflection area from the reflection point and the time difference calculated by the time difference calculation unit for the two or more elements. A local sound speed determination unit that determines a local sound speed in the out-of-range region from the at least one individual sound speed may be provided.

A time difference calculation includes an image generation unit that generates an ultrasonic image based on a plurality of element data output from the first plurality of elements, and a region of interest setting unit that sets a region of interest on the ultrasonic image. The unit includes one of the plurality of second elements that has received an ultrasonic echo passing through a region other than the region of interest among the plurality of first elements, and a reference element among the plurality of second elements. A plurality of time differences can be calculated using elements other than the measurement elements as measurement elements.
Furthermore, the sound speed calculation unit calculates the distance from the reflection point to the two or more elements that have received the ultrasonic echo passing through the region of interest and the time difference calculated by the time difference calculation unit for the two or more elements. A local sound speed determination unit that determines a local sound speed in the region of interest from the at least one individual sound speed may be provided.

The total sound speed determination unit is configured to display a region of interest set by the region of interest setting unit when the region of interest set by the region of interest setting unit has at least one of a length in the scanning direction and a length in the depth direction equal to or less than a set value. When the length in the scanning direction and the length in the depth direction are both larger than the set value, and the straight line passing through the region of interest among the plurality of straight lines connecting the reflection point and the first plurality of elements is equal to or less than a predetermined ratio It can only be configured to determine the overall sound speed.
Further, the local sound speed determination unit may determine the local sound speed only when the length in the scanning direction and the length in the depth direction of the region of interest set by the region of interest setting unit are both larger than the set value.

The region-of-interest setting unit may set the region of interest by the user's specification, or may automatically set the region of interest by performing image analysis on the ultrasound image.
The element data memory transmits a plurality of element data output from each of the first plurality of elements to the plurality of reflection points by transmitting an ultrasonic beam toward the plurality of reflection points located on different scanning lines. The time difference calculation unit calculates a plurality of time differences for each of the plurality of reflection points, the sound speed calculation unit calculates a plurality of individual sound speeds for each of the plurality of reflection points, and the overall sound speed determination unit It is also possible to determine the overall sound speed based on a plurality of individual sound speeds respectively calculated for a plurality of reflection points by the sound speed calculation unit.

The local sound speed determination unit calculates the distance from each of the plurality of reflection points to two or more elements that have received the ultrasonic echoes passing through the deviated region, and the time difference for each of the plurality of reflection points and the two or more elements. The local sound speed in the outlier region may be determined from the plurality of sound speeds calculated by the sound speed calculation unit based on the plurality of time differences calculated by the unit.

The element data memory also transmits a plurality of elements that are output from the second plurality of elements to the plurality of reflection points by transmitting ultrasonic beams toward the plurality of reflection points located on different scanning lines. The time difference calculation unit calculates a plurality of time differences for each of the plurality of reflection points, and the sound speed calculation unit calculates a plurality of individual sound velocities for each of the plurality of reflection points. Can also determine the overall sound speed based on a plurality of individual sound speeds respectively calculated for a plurality of reflection points by the sound speed calculation unit.

The local sound velocity determination unit calculates the distance from each of the plurality of reflection points to two or more elements that have received an ultrasonic echo passing through the region of interest, and the time difference for each of the plurality of reflection points and the two or more elements. The local sound speed in the region of interest may be determined from the plurality of sound speeds calculated by the sound speed calculation section based on the plurality of time differences calculated by the section.

The sound velocity quantifying method according to the present invention is based on the first plurality of elements of the array transducer that has received the ultrasonic echo reflected by the reflection point in response to transmission of the ultrasonic beam toward the reflection point in the subject. A plurality of element data to be output are stored, element data corresponding to a reference element which is one element of the first plurality of elements, and a plurality of elements other than the reference element among the first plurality of elements. Calculate a plurality of time differences between a plurality of element data corresponding to a plurality of measurement elements that are elements, a distance from a reflection point to a reference element, a distance from a reflection point to a plurality of measurement elements, A plurality of individual sound velocities corresponding to a plurality of measurement elements are calculated based on the plurality of calculated time differences, respectively, and an overall sound speed is determined based on the calculated plurality of individual sound velocities.

According to this invention, a plurality of element data output from the first plurality of elements of the array transducer are stored, one of the first plurality of elements is used as a reference element, and the remaining plurality of elements are stored. A plurality of measurement elements, a plurality of time differences between element data corresponding to the reference element and a plurality of element data corresponding to the plurality of measurement elements are calculated, and the distance from the reflection point to the reference element, A plurality of individual sound velocities corresponding to the plurality of measurement elements are calculated based on the distance from the reflection point to the plurality of measurement elements and the calculated plurality of time differences, respectively, and based on the calculated plurality of individual sound velocities. Since the overall sound speed is determined, the sound speed can be accurately quantified even when the sound speed is not uniform in the region between the first plurality of elements of the array transducer and the reflection point.

1 is a block diagram showing a configuration of an ultrasonic diagnostic apparatus according to Embodiment 1 of the present invention. 3 is a block diagram showing an internal configuration of a receiving circuit in the first embodiment. FIG. 3 is a block diagram illustrating an internal configuration of an image generation unit according to Embodiment 1. FIG. 4 is a block diagram showing an internal configuration of a sound speed quantification unit in Embodiment 1. FIG. It is a figure which shows a mode that the ultrasonic echo from the reflective point in a subject arrives at the 1st some element of an array transducer. It is a figure which shows the ultrasonic echo emitted from the reflective point in a subject and toward each element. It is a figure which shows the waveform which connects the point with the largest amplitude of the ultrasonic echo which is emitted from the reflective point in a subject and goes to each element. It is a figure which shows the geometric arrangement | positioning relationship of the reflective point in a subject, and the 1st some element of an array transducer. It is a graph which shows the time which receives the ultrasonic echo from each reflection point by each element when the lesioned part does not exist in the area between each element from the reflection point in the subject. It is a graph which shows the individual sound speed corresponding to each element. It is a figure which shows the whole area | region and a detached area. It is a graph which shows the time which receives the ultrasonic echo from a reflective point by each element in case a lesioned part exists in the area | region between each reflective element in a subject. 3 is a flowchart showing an operation of the ultrasonic diagnostic apparatus according to the first embodiment. FIG. 10 is a diagram illustrating a state in which an ultrasonic echo from one reflection point in the second embodiment reaches a first plurality of elements of an array transducer. It is a figure which shows a mode that the ultrasonic echo from the other reflective point in Embodiment 2 arrives at the 1st some element of an array transducer. 6 is a flowchart showing the operation of the ultrasonic diagnostic apparatus according to the second embodiment. 6 is a block diagram illustrating a configuration of an ultrasonic diagnostic apparatus according to Embodiment 3. FIG. 6 is a block diagram showing an internal configuration of a sound velocity quantifying unit of an ultrasonic diagnostic apparatus according to Embodiment 3. FIG. FIG. 10 is a diagram showing a geometric arrangement relationship between an element that has received an ultrasonic echo that passes through a region other than a region of interest in Embodiment 3 and a reflection point in a subject. 12 is a graph showing the time at which an ultrasonic echo from a reflection point in a subject is received by each element that has received an ultrasonic echo passing through a region other than the region of interest in the third embodiment. FIG. 10 is a diagram showing a geometric arrangement relationship between an element that has received an ultrasonic echo passing through a region of interest and a reflection point in a subject in the third embodiment. 10 is a graph showing the time at which an ultrasonic echo from a reflection point in a subject is received by each element that has received an ultrasonic echo passing through a region of interest in the third embodiment. 10 is a flowchart showing the operation of the ultrasonic diagnostic apparatus according to the third embodiment. 10 is a flowchart showing the operation of the ultrasonic diagnostic apparatus according to the fourth embodiment. 10 is a flowchart showing the operation of the ultrasonic diagnostic apparatus according to the fifth embodiment. 3 is a flowchart showing an operation of a quantification process 100. 5 is a flowchart showing an operation of a quantification process 200. 10 is a flowchart showing an operation of an ultrasonic diagnostic apparatus according to a modification of the fifth embodiment. 5 is a flowchart showing an operation of a quantification process 300.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
Embodiment 1
FIG. 1 shows the configuration of an ultrasonic diagnostic apparatus according to Embodiment 1 of the present invention. The ultrasonic diagnostic apparatus includes an array transducer 1, and a transmission circuit 2 and a reception circuit 3 are connected to the array transducer 1. An image generating unit 4, a display control unit 5, and a display unit 6 are sequentially connected to the receiving circuit 3. An element data memory 7 is connected to the receiving circuit 3, and a sound speed quantification unit 8 is connected to the element data memory 7 and the image generation unit 4.
Further, a control unit 9 is connected to each of the transmission circuit 2, the reception circuit 3, the image generation unit 4, the display control unit 5, and the sound speed quantification unit 8, and the operation unit 10 and the storage unit 11 are connected to the control unit 9. .

The array transducer 1 has a first plurality of elements (ultrasonic transducers) arranged one-dimensionally or two-dimensionally. Each of these elements transmits an ultrasonic wave according to a drive signal supplied from the transmission circuit 2 and receives an ultrasonic echo from the subject to output a reception signal. Each element is, for example, a piezoelectric ceramic represented by PZT (lead zirconate titanate), a polymer piezoelectric element represented by PVDF (polyvinylidene fluoride), or PMN-PT (magnesium niobate / lead titanate solid solution). It is comprised by the vibrator | oscillator which formed the electrode in the both ends of the piezoelectric material which consists of a piezoelectric single crystal etc. which are represented by.

When a pulsed or continuous wave voltage is applied to the electrodes of such a vibrator, the piezoelectric body expands and contracts, and pulsed or continuous wave ultrasonic waves are generated from the respective vibrators, and the synthesis of those ultrasonic waves. As a result, an ultrasonic beam is formed. In addition, each transducer generates an electric signal by expanding and contracting by receiving propagating ultrasonic waves, and these electric signals are output as ultrasonic reception signals.

The transmission circuit 2 includes, for example, a plurality of pulse generators, and is transmitted from the first plurality of elements of the array transducer 1 based on the transmission delay pattern selected according to the control signal from the control unit 9. The delay amount of each drive signal is adjusted so as to form an ultrasonic beam by the ultrasonic wave to be supplied to the first plurality of elements.
As shown in FIG. 2, the reception circuit 3 has a configuration in which an amplification unit 12 and an AD (Analogue Digital) conversion unit 13 are connected in series. The receiving circuit 3 amplifies the reception signal output from each element of the array transducer 1 by the amplifying unit 12, and digitizes the element data obtained by the AD converting unit 13. The image generating unit 4 and the element data memory 7 Output to.

As shown in FIG. 3, the image generation unit 4 has a configuration in which a signal processing unit 14, a DSC (Digital Scan Converter) 15, and an image processing unit 16 are sequentially connected in series.
Based on the reception delay pattern selected according to the control signal from the control unit 9, the signal processing unit 14 gives each element data a respective delay and adds (phased addition) according to the set sound speed. Receive focus processing. By this reception focus processing, a sound ray signal in which the focus of the ultrasonic echo is narrowed is generated. Further, the signal processing unit 14 corrects the attenuation by the distance according to the depth of the reflection position of the ultrasonic wave on the sound ray signal, and then performs envelope detection processing to thereby obtain a tomography relating to the tissue in the subject. A B mode (Brightness Mode) image signal which is image information is generated.

The DSC 15 converts (raster conversion) the B-mode image signal generated by the signal processing unit 14 into an image signal according to a normal television signal scanning method.
The image processing unit 16 performs various necessary image processing such as gradation processing on the B-mode image signal input from the DSC 15, and then outputs the B-mode image signal to the display control unit 5.

The display control unit 5 displays an ultrasound diagnostic image on the display unit 6 based on the B-mode image signal output from the image generation unit 4.
The display unit 6 includes a display device such as an LCD (Liquid Crystal Display), for example, and displays an ultrasound diagnostic image under the control of the display control unit 5.

The element data memory 7 sequentially stores element data output from the receiving circuit 3.
The sound velocity quantifying unit 8 uses the element data stored in the element data memory 7 to remove the entire sound velocity V1 indicating the sound velocity of the entire imaging area imaged by the array transducer 1 and the lesion in the imaging area. The local sound speed V2 indicating the sound speed of the region is quantified and output to the image generation unit 4. As shown in FIG. 4, the sound speed quantification unit 8 includes a time difference calculation unit 21 and a sound speed calculation unit 22, and the sound speed calculation unit 22 includes an overall sound speed determination unit 23, an outlier region specifying unit 24, and a local sound speed. Each determination unit 25 is connected. Furthermore, the overall sound speed determining unit 23, the off-region specifying unit 24, and the local sound speed determining unit 25 are sequentially connected in series.

The control unit 9 controls each unit of the ultrasonic diagnostic apparatus based on a command input from the operation unit 10 by the user.
The operation unit 10 is for a user to perform an input operation, and can be formed from a keyboard, a mouse, a trackball, a touch panel, or the like.
The storage unit 11 stores an operation program and the like. A hard disk, a flexible disk, an MO (Magneto-Optical Disk), an MT (Magnetic Tape), a RAM (Random Access Memory), a CD-ROM (Compact Disk Read Only Memory). Recording media such as DVD-ROM (Digital Versatile Disk Read Only Memory), SD card (Secure Digital Card), CF card (Compact Flash Card), USB memory (Universal Serial Bus Memory), or server can be used. .
The image generation unit 4, the display control unit 5, the sound speed quantification unit 8, and the control unit 9 are composed of a CPU (CenTsal Processing Unit) and an operation program for causing the CPU to perform various processes. May be constituted by a digital circuit. Further, the image generation unit 4, the display control unit 5, the sound speed quantification unit 8, and the control unit 9 can be partially or entirely integrated into one CPU.

Here, the operation of the sound velocity quantification unit 8 will be described in detail.
The time difference calculation unit 21 corresponds to the ultrasonic wave transmitted from the first plurality of elements of the array transducer 1 toward the reflection point in the subject from among the element data stored in the element data memory 7. The element data output from the first plurality of elements of the array transducer 1 that has received the ultrasonic echo reflected by the reflection point is read out. Then, one of the first plurality of elements of the array transducer 1 is set as a reference element, the remaining elements that are not reference elements are set as measurement elements, element data corresponding to the reference elements, By comparing the element data corresponding to each measurement element, a plurality of time differences between the element data of the reference element and the element data of each measurement element are calculated.

For example, as shown in FIG. 5, n is an integer of 2 or more, and an ultrasonic beam is transmitted from the first plurality of elements E1 to En of the array transducer 1 with the reflection point A in the subject as a focal point, and reflected. It is assumed that the ultrasonic echo reflected by the point A is received by the first plurality of elements E1 to En. The time at which the ultrasonic echo from the reflection point A is received by each element with the point in time when the ultrasonic echo is emitted from the reflection point A as a function of the distance between the reflection point A and each element. It becomes. As shown in FIG. 6, among the first plurality of elements E1 to En, the element Ec having the shortest distance from the reflection point A receives the earliest ultrasonic echo and is arranged at a position away from the element Ec. Since the distance from the reflection point A becomes larger as the element is located, the ultrasonic echo is received later.

As shown in FIG. 5, when the lesioned part B exists on the path of the ultrasound echo and the sound speed at the lesioned part B is higher than the surrounding sound speed, the ultrasound echo that has passed through the lesioned part B is The time received by the corresponding element is advanced by the amount that has passed through the high sound velocity region. FIG. 7 shows a representative point of the ultrasonic echo where the maximum amplitude of the ultrasonic echo directed to each element shown in FIG. 6 is represented. As shown in FIG. 7, the ultrasonic echoes that have passed through the lesion B and received by the element Es and the element Et are considered even if the geometrical positional relationship between the reflection point and each element is considered. It can be seen that the arrival time is deviated from the ultrasonic echoes received by other elements. Here, s and t are integers in the range of 1 to n.

Therefore, as shown in FIG. 8, there is no lesion in the entire region R1 between the first plurality of elements Ei to En and the reflection point A, where i is an integer within an arbitrary range of 1 to n. In this case, by recording the time Ti at which the element Ei receives the ultrasonic echo from the reflection point A with the point in time when the ultrasonic echo is emitted from the reflection point A, each element as shown in FIG. A graph representing the time when the ultrasonic echo is received is obtained. Specifically, based on the amplitude information of the element data corresponding to the first plurality of elements E1 to En, the time at which each element receives the ultrasonic echo can be obtained. Alternatively, the waveform of the element data corresponding to the first plurality of elements E1 to En and the waveform of the element data when each of the previously stored elements receives an ultrasonic echo are known patterns such as a pattern matching method. The time at which each element receives the ultrasonic echo can also be obtained by comparison using a method.

Further, if k is an integer in an arbitrary range of 1 to n, the element data and the element data of the element Ek are determined by the time Tk when the element Ek receives the ultrasonic echo and the time Ti when the element Ei receives the ultrasonic echo. The time difference ΔT from the element data of Ei is ΔT = Ti−Tk. In this way, the time difference ΔT is calculated based on the time at which the element Ei and the element Ek receive the ultrasonic echo.

Here, the sound speed corresponding to the area between the reflection point A in the subject and each element is the individual sound speed. The sound speed calculation unit 22 calculates the individual sound speed Va in the entire region R1 based on the time difference ΔT calculated by the time difference calculation unit 21 and the distances from the reflection point A to the elements Ei and Ek. As shown in FIG. 8, when the distance from the element Ek to the reflection point A is Lk and the distance from the element Ei to the reflection point A is Li, it corresponds to the element Ei and the element Ek based on the calculated time difference ΔT. The individual sound velocity Va is Va = (Li−Lk) / (Ti−Tk). Thus, the individual sound velocity Va can be calculated by using the two elements of the element Ei and the element Ek.

When the time difference calculation unit 21 sets one of the first plurality of elements E1 to En as a reference element and a plurality of elements other than the remaining reference elements as measurement elements, the reference element is ultrasonic. A plurality of time differences ΔT are calculated by comparing the time when the echo is received and the time when the plurality of measuring elements receive the ultrasonic echo. Based on the calculated plurality of time differences ΔT and the geometrical arrangement of the reflection point A and the first plurality of elements E1 to En, the sound speed calculation unit 22 generates a plurality of individual sound speeds Va corresponding to the entire region R1. Calculated.

Based on the plurality of individual sound speeds Va thus calculated, the total sound speed determination unit 23 determines the total sound speed V1 corresponding to the entire region R1 between the first plurality of elements E1 to En and the reflection point A. To do. For example, a histogram of a plurality of individual sound speeds Va calculated by the sound speed calculation unit 22 can be created, and the individual sound speed Va having the highest frequency can be determined as the overall sound speed V1.
Note that the individual sound velocity Va corresponding to the reference element cannot be calculated by the above-described method, but can be obtained by interpolation using the individual sound speed Va corresponding to the measurement elements around the reference element. .

On the other hand, when a lesion is present in the region between the first plurality of elements E1 to En and the reflection point A, the geometric arrangement of the reflection point A and the first plurality of elements E1 to En and the respective measurements are performed. When the sound speed calculation unit 22 calculates a plurality of individual sound velocities Va corresponding to a plurality of measurement elements based on the time difference ΔT corresponding to the element for use, the graph shown in FIG. 10 is obtained.
As shown in FIG. 10, when the ultrasonic echo passes through the lesion and travels toward the element Es and the element Et, the individual sound velocity Va corresponding to the element Es and the element Et corresponds to an element other than the element Es and the element Et. It has a higher value than the individual sound velocity Va. This is presumably because the ultrasonic echo directed toward the element Es and the element Et passed through the lesioned part B having a higher sound speed than the surrounding sound speed, as shown in FIG.

Based on the plurality of individual sound speeds Va calculated in this way, the overall sound speed determination unit 23 creates a histogram of the plurality of individual sound speeds Va, and determines the most frequent individual sound speed Va as the total sound speed V1.
The outlier specifying unit 24 determines whether or not the absolute value of the difference ΔD between the total sound speed V1 determined by the total sound speed determination unit 23 and the individual sound speed Va calculated by the sound speed calculation unit 22 exceeds the speed threshold Thv. To do. That is, the difference ΔD between the plurality of individual sound velocities Va and the total sound speed V1 corresponding to the first plurality of elements E1 to En shown in FIG. 10 is calculated, respectively, and the absolute value and speed threshold value of each difference ΔD are calculated. Compare Thv. If the absolute value of the difference ΔD between the individual sound speed Va and the overall sound speed V1 corresponding to the elements Es and Et shown in FIG. 10 exceeds the speed threshold value Thv, as shown in FIG. The area between the element Es and the element Et corresponding to the reflection point A and the reflection point A is specified as the out-of-range area R2.
The speed threshold Thv is determined by the difference in sound speed assumed between the normal tissue and the diseased tissue, or the resolution of sound speed value calculation in this ultrasonic diagnostic apparatus, and is preferably 50 m / sec or less. 30 m / sec or less is more desirable, and about 10 m / sec is most desirable.

Next, the sound velocity calculation unit 22 calculates the individual sound velocity Vb in the deviating region R2 using the elements Es and Et that have received the ultrasonic echoes passing through the deviating region R2.
As shown in FIG. 11, when a lesion B exists between the first plurality of elements E1 to En and the reflection point A, the time when the ultrasonic echo from the reflection point A is received is recorded. A graph representing the time at which each element receives the ultrasonic echo as shown in FIG. 12 is obtained. Based on the time Ts and the time Tt at which the element Es and the element Et shown in FIG. 12 receive the ultrasonic echoes, the time difference calculation unit 21 generates a difference between the element data corresponding to the element Es and the element data corresponding to the element Et. A time difference ΔT is calculated.
Then, as shown in FIG. 11, the sound velocity calculation unit 22 sets the distance from the reflection point A to the element Es as Ls, and sets the distance from the reflection point A to the element Et as Lt, and individually corresponds to the element Es and the element Et. The speed of sound Vb is calculated as Vb = (Lt−Ls) / (Tt−Ts).

Here, when the time difference calculation unit 21 sets one of the plurality of elements that have received the ultrasonic echoes that have passed through the out-of-range region R2 as a reference element, and other than the reference element as a plurality of measurement elements, A plurality of time differences ΔT are calculated based on the time at which the reference element receives the ultrasonic echo that has passed through the out-of-range region R2 and the time at which the plurality of measurement elements have received the ultrasonic echo that has passed through the lesioned part B. Based on the calculated plurality of time differences ΔT and the geometrical arrangement of the plurality of elements that receive the ultrasonic echoes that have passed through the reflection point A and the detachment region R2, the sound velocity calculation unit 22 corresponds to the detachment region R2. A plurality of individual sound speeds Vb are calculated.

A histogram is created by the local sound speed determination unit 25 based on the plurality of individual sound speeds Vb calculated in this way, and the individual sound speed Vb having the highest frequency is determined as the local sound speed V2 of the out-of-range region R2.
Note that, when there are only two elements that receive ultrasonic echoes that pass through the lesion B, only one individual sound velocity Vb is calculated. The local sound speed determination unit 25 uses the individual sound speed Vb as the local sound velocity V2. Can be determined as

Next, the operation of the first embodiment will be described with reference to the flowchart of FIG.
First, in step S1, ultrasonic waves are transmitted and received only once from the first plurality of elements E1 to En of the array transducer 1 toward the reflection point A in the subject, and element data is acquired in step S2. The That is, ultrasonic waves are transmitted from the first plurality of elements E1 to En to the reflection point A according to the drive signal supplied from the transmission circuit 2, and from the elements E1 to En that have received the ultrasonic echoes from the reflection point A. A reception signal is output to the reception circuit 3, element data is generated by the reception circuit 3, and sequentially stored in the element data memory 7.

Next, in step S3, the time difference calculation unit 21 compares the element data corresponding to the reference element and the element data corresponding to each measurement element, and the element data of the reference element and each measurement data are measured. A time difference ΔT between the element data and the element data is calculated. Further, in step S4, based on the geometric arrangement of the plurality of measurement elements of the array transducer 1 and the time difference ΔT, the sound speed calculation unit 22 calculates a plurality of individual sound velocities Va corresponding to the plurality of measurement elements. Based on the plurality of individual sound speeds Va calculated in this way, the overall sound speed V1 is determined by the overall sound speed determination unit 23 in step S5.

Thereafter, in step S6, it is determined whether or not the out-of-region R2 exists by the out-of-region specifying unit 24. When the out-of-region R2 is specified, in step S7, at least one individual sound velocity Vb in the out-of-region R2 is calculated. In step S8, the local sound speed determination unit 25 determines the local sound speed V2 in the out-of-range region R2.
Note that since the absolute value of the difference ΔD between each individual sound velocity Va calculated in step S4 and the total sound velocity V1 is equal to or less than the speed threshold value Thv, the deviating region R2 is detected by the deviating region specifying unit 24 in step S6. Is not specified, the process proceeds to step S9, and an error display indicating that the out-of-range region R2 does not exist is displayed.

Further, a B-mode image signal is generated by the image generator 4 based on the element data generated by the receiving circuit 3 by scanning the ultrasonic beam from the first plurality of elements E1 to En of the array transducer 1. The B-mode image signal is output to the display control unit 5 and the ultrasonic image is displayed on the display unit 6.
The total sound speed V1 and the local sound speed V2 determined by the sound speed quantification unit 8 are output to the image generation unit 4, and the values of the total sound speed V1 and the local sound speed V2 are displayed on the display unit 6 together with the ultrasonic image. Only the value of the local sound speed V2 may be displayed instead of both the overall sound speed V1 and the local sound speed V2. When it is determined that there is no region where the sound speed is locally different and error display is performed in step S9, only the entire sound speed V1 can be displayed.

Further, based on the total sound speed V1 and the local sound speed V2 output from the sound speed quantification unit 8, the image generation unit 4 generates a B-mode image signal using the total sound speed V1 for the entire area R1 excluding the outlier area R2. For the out-of-range region R2, a B-mode image signal using the local sound velocity V2 can be generated. In this way, it is possible to generate a high-quality ultrasonic image in the entire region R1 excluding the detachment region R2 and also in the detachment region R2.

Note that the individual sound velocities Va and Vb are any two elements, that is, the distance between the reference element and the measurement element and the reflection point A in the subject, and the element data and the measurement element corresponding to the reference element. Is calculated based on the time difference ΔT obtained by comparing the element data corresponding to.
At this time, if the interval between the reference element and the measuring element is set to be narrow, the time difference ΔT is reduced and the range for calculating the sound speed is narrowed, and the accuracy of calculation of the individual sound speeds Va and Vb is improved. On the other hand, if the interval between the reference element and the measuring element is set wide, the range in which the sound speed is calculated is widened, and there is a possibility that the spatial resolution of the local sound speed is reduced. For this reason, it is desirable that the interval between the reference element and the measuring element is set as narrow as possible within a range in which the time resolution in the ultrasonic diagnostic apparatus can tolerate the time difference ΔT.

Further, it is possible to calculate a plurality of individual sound velocities Va while sequentially changing the reference elements without fixing the element set as the reference element to one of the first plurality of elements E1 to En. it can. For example, if m is an integer in the range of 1 to n−1, the reference element is set to Em and the measurement element is set to Em + 1, and the individual sound velocity Va is calculated while sequentially changing the value of m, the reference element A plurality of individual sound velocities Va can be calculated while sequentially changing the element Em and the measuring element Em + 1.

As described above, elements that are adjacent to each other are used to narrow the range in which the sound speed is calculated, so that the accuracy of calculating the individual sound speed Va is improved, and the positional relationship between the reference element and the measuring element and other elements is improved. Since it is changed sequentially, it becomes easy to identify the lesioned part B having a sound speed different from the peripheral sound speed.
In the first embodiment, when the lesioned part B is located between the reference element and the reflection point A in the subject, the reference element receives an ultrasonic echo that has passed through the lesioned part B. Therefore, it may be difficult to specify the lesion B, but this situation can be avoided by calculating a plurality of individual sound velocities Va while sequentially changing the reference element Em and the measurement element Em + 1. it can.

The elements used to calculate the individual sound velocity Va do not necessarily have to be adjacent to each other. For example, x is an arbitrary integer of 2 or more, the reference element is set to Em, and the measurement element is set to Em + x. When the individual sound velocity Va is calculated while sequentially changing the reference element Em and the measuring element Em + x by sequentially changing the value of m, a plurality of individual sound velocities are provided at a rough element interval with an element interval corresponding to x elements. Va can be calculated. A histogram of a plurality of calculated individual sound velocities Va is created, and an element corresponding to the most frequent individual sound speed Va is set as a reference element. It is possible to avoid the lesion B having different sound speeds from being located.

Embodiment 2
In the first embodiment, the total sound speed V1 and the local sound speed V2 are quantified by transmitting and receiving ultrasonic waves only once toward one reflection point A in the subject. Thus, it is possible to quantify the total sound speed V1 and the local sound speed V2 by transmitting and receiving ultrasonic waves once each.
For example, as shown in FIG. 14, element data obtained by transmitting and receiving ultrasonic waves once toward the reflection point Av on one scanning line Cv, and as shown in FIG. 15, the scanning line Element data acquired by performing ultrasonic wave transmission / reception once toward the reflection point Aw on the scanning line Cw different from Cv is used.

As shown in the flowchart of FIG. 16, in the second embodiment, in step S1, ultrasonic waves are emitted only once from the first plurality of elements E1 to En of the array transducer 1 toward the reflection point Av in the subject. The element data is acquired and stored in the element data memory 7 in step S2.
In subsequent step S10, it is determined whether or not the transmission / reception of ultrasonic waves to / from the plurality of set reflection points is completed. If it is determined that the transmission / reception is not completed, the reflection point is changed in step S11, and then the step is performed. S1 and S2 are repeated. That is, instead of the scanning line Cv to the scanning line Cw, ultrasonic waves are transmitted / received only once toward the reflection point Aw, and element data is acquired and stored in the element data memory 7.

If it is determined in step S10 that transmission / reception of ultrasonic waves at all reflection points has been completed, in step S3, the time difference calculation unit 21 of the sound velocity quantification unit 8 corresponds to the reflection points Av and Aw respectively for reference. The element data corresponding to the element and the element data corresponding to the plurality of measurement elements are compared to calculate a plurality of time differences ΔT. In step S4, the sound speed calculation unit 22 causes the first plurality of elements E1 to E1 to be compared. A plurality of individual sound velocities Va are calculated corresponding to each of the reflection points Av and Aw based on the geometrical arrangement of En and the calculated time difference ΔT.
Further, in step S5, the total sound speed determination unit 23 creates a histogram of a plurality of individual sound speeds Va corresponding to the reflection points Av and Aw, and the individual sound speed Va having the highest frequency is the total sound speed V1 in the entire region R1. As determined.

Thereafter, in step S6, the out-of-region specifying unit 24 determines whether or not the out-of-region R2 exists for each of the reflection points Av and Aw. When the out-of-region R2 is specified, the out-of-region R2 is specified in step S7. The individual sound speed Vb is calculated corresponding to each of the reflection points Av and Aw in which the region R2 is specified. Further, in step S8, the calculated individual sound speed Vb is deviated by the local sound speed determination unit 25 from the local sound speed in the region R2. Determined as V2.
In step S6, when the outlying region R2 is specified by only one of the plurality of reflection points Av and Aw, the local sound velocity V2 can be determined for the reflection point.

Thus, by transmitting / receiving ultrasonic waves to / from a plurality of reflection points to acquire element data, the total sound speed V1 and the local sound speed V2 can be quantified with higher accuracy.

Embodiment 3
In the first and second embodiments, the outlier region R2 is specified and the local sound velocity V2 corresponding to the outlier region R2 is quantified. However, in the third embodiment, the region of interest R2A is set to correspond to the region of interest R2A. The local sound speed V2 is quantified.
FIG. 17 shows the configuration of the ultrasonic diagnostic apparatus according to the third embodiment. The ultrasonic diagnostic apparatus according to the third embodiment uses a sound velocity quantifying unit 8A instead of the sound velocity quantifying unit 8 in the configuration of the ultrasonic diagnostic apparatus according to the first embodiment shown in FIG. The region setting unit 17 is provided, and the sound velocity quantifying unit 8A and the control unit 9 are connected to the region of interest setting unit 17. FIG. 18 shows the internal configuration of the sound speed quantification unit 8A. The sound speed quantification unit 8A includes the out-of-range region specifying unit 24 in the sound speed quantification unit 8 shown in FIG. 4 of the first embodiment. In addition, the time difference calculation unit 21, the overall sound speed determination unit 23, and the local sound speed determination unit 25 are each connected to the region of interest setting unit 17.

The region-of-interest setting unit 17 sets the region of interest R2A within the imaging region imaged by the array transducer 1. The region of interest R2A is set, for example, according to the position of the lesion, and the region of interest setting unit 17 sets the region of interest R2A based on the user's designation input from the operation unit 10, or the image generating unit 4 By analyzing the generated ultrasonic image, it is possible to automatically set the region of interest R2A as a specific region different from the surrounding such as a lesion.

The time difference calculation unit 21 is an element corresponding to an element that receives an ultrasonic echo that passes through the region R1A other than the region of interest R2A set by the region of interest setting unit 17 when the total sound speed determination unit 23 determines the total sound velocity V1. Based on the data, a first time difference ΔT1 is calculated.
In FIG. 19, when the time at which an element that receives an ultrasonic echo passing through the region R1A other than the region of interest R2A receives the ultrasonic echo is recorded, a graph as shown in FIG. 20 is obtained. In FIG. 20, Er represents two or more elements that have received an ultrasonic echo passing through the region of interest R2A, and the reception time of the ultrasonic echo corresponding to this element Er is blank.

Here, if k is an integer in the range of 1 to n, the element data of the element Ek and the element Ei are determined by the time Tk when the element Ek receives the ultrasonic echo and the time Ti when the element Ei receives the ultrasonic echo. The first time difference ΔT1 with the element data is ΔT1 = Ti−Tk.
Then, as shown in FIG. 19, when the distance from the element Ek to the reflection point A is Lk and the distance from the element Ei to the reflection point A is Li, the individual sound velocity Va corresponding to the element Ei is Va = (Li −Lk) / (Ti−Tk). As shown in the first embodiment, the individual sound velocity Va can be calculated using two elements.

Further, the time difference calculation unit 21 uses one of the second plurality of elements E1 to En that has received the ultrasonic echo passing through the region R1A as a reference element, and a plurality of elements other than the reference element as measurement elements. Set to. The time difference calculation unit 21 calculates a plurality of first time differences ΔT1 based on the time at which each element that has received the ultrasonic echo passing through the region R1A has received the ultrasonic echo.

Based on the plurality of first time differences ΔT1 calculated by the time difference calculation unit 21 and the geometrical arrangement of the second plurality of elements E1 to En and the reflection point A that have received the ultrasonic echoes passing through the region R1A. Thus, the sound speed calculation unit 22 calculates a plurality of individual sound speeds Va. Then, a histogram of a plurality of individual sound speeds Va calculated by the sound speed calculation unit 22 is created by the overall sound speed determination unit 23, and the individual sound speed Va having the highest frequency is determined as the overall sound speed V1 corresponding to the region R1A.
In the case where no lesion exists in the region R1A other than the region of interest R2A and the sound speed of the region R1A can be considered to be uniform, the average value of the plurality of individual sound speeds Va is set to the overall sound speed corresponding to the region R1A. It can also be determined as V1.

Further, as shown in FIG. 21, the individual sound velocity Vb in the region of interest R2A can be calculated using the element Es and the element Et that have received the ultrasonic echo passing through the region of interest R2A. Here, s and t are integers in the range of 1 to n.
In FIG. 21, when the time at which an element that receives an ultrasonic echo passing through the region of interest R2A receives the ultrasonic echo is recorded, a graph as shown in FIG. 22 is obtained. In FIG. 22, the reception time of the ultrasonic echo corresponding to the element other than the element Er that has received the ultrasonic echo passing through the region of interest R2A is blank.

As shown in FIG. 21, on the path of the ultrasonic echo reaching the element Es from the reflection point A through the region of interest R2A, the distance from the reflection point A to the region of interest R2A is Ls1, and the distance in the region of interest R2A is Ls2, the distance from the region of interest R2A to the element Es is Ls3, the time to reach the region of interest R2A from the reflection point A is Ts1, the time to pass the region of interest R2A is Ts2, and the time to reach the element Es from the region of interest R2A is Ts3 Then, the time Ts that the ultrasonic echo reaches from the reflection point A through the region of interest R2A to the element Es is expressed as Ts = Ts1 + Ts2 + Ts3, and the time that has passed through the region R1A other than the region of interest R2A is (Ts1 + Ts3). expressed. Since the total sound speed V1 of the region R1A other than the region of interest R2A is determined by the total sound speed determination unit 23, the time (Ts1 + Ts3) that has passed through the region R1A is (Ts1 + Ts3) = (Ls1 + Ls3) / V1. The time Ts2 that has passed through the region of interest R2A is Ts2 = Ts− (Ts1 + Ts3).

Further, on the path of the ultrasonic echo reaching from the reflection point A to the element Et through the region of interest R2A, the distance from the reflection point A to the region of interest R2A is Lt1, the distance in the region of interest R2A is Lt2, and the region of interest R2A is Assuming that the distance to the element Et is Lt3, the time to reach the region of interest R2A from the reflection point A is Tt1, the time to pass through the region of interest R2A is Tt2, and the time to reach the element Es from the region of interest R2A is Ts3. The time Tt from which the ultrasonic echo reaches the element Et through the region of interest R2A is expressed as Tt = Tt1 + Tt2 + Tt3, and the time of passing through the region R1A other than the region of interest R2A is expressed as (Tt1 + Tt3). Furthermore, the time (Tt1 + Tt3) that has passed through the region R1A is (Tt1 + Tt3) = (Lt1 + Lt3) / V1. The time Tt2 that has passed through the region of interest R2A is Tt2 = Tt− (Tt1 + Tt3).
The time difference calculator 21 calculates the second time difference ΔT2 between the element data of the element Es and the element data of the element Et as ΔT2 = (Tt2−Ts2), and the sound speed calculator 22 calculates Vb = (Lt2−). The individual sound velocity Vb corresponding to the element Es and the element Et can be calculated as Ls2) / (Tt2-Ts2).

Here, when the time difference calculation unit 21 sets one of a plurality of elements that have received an ultrasonic echo passing through the region of interest R2A as a reference element, and other than the reference element as a plurality of measurement elements, A plurality of second time differences ΔT2 are calculated based on the time when the reference element receives the ultrasonic echo and the time when the plurality of measuring elements receive the ultrasonic echo. Based on the calculated second time differences ΔT2 and the geometrical arrangement of the plurality of elements that receive the ultrasonic echoes that have passed through the reflection point A and the region of interest R2A, the sound velocity calculation unit 22 causes the region of interest R2A to A plurality of individual sound speeds Vb are calculated.

A histogram is created by the local sound speed determination unit 25 for the plurality of individual sound speeds Vb calculated in this manner, and the individual sound speed Vb having the highest frequency is determined as the local sound speed V2 of the region of interest R2A.
When the region of interest R2A is set as a lesion, the sound speed of the region of interest R2A is considered to be uniform. Therefore, the average value of the plurality of individual sound speeds Vb corresponding to the region of interest R2A is set as the local sound speed V2. It can also be determined. In addition, when there are only two elements that receive an ultrasonic echo that passes through the region of interest R2A, only one individual sound velocity Vb is calculated. The local sound speed determination unit 25 uses this individual sound speed Vb as the local sound speed V2. Can be determined as

Next, the operation of the third embodiment will be described with reference to the flowchart of FIG.
First, in step S12, the region of interest R2A is set by the region-of-interest setting unit 17 between the first plurality of elements E1 to En of the array transducer 1 and the reflection point A in the subject.
In subsequent step S2, ultrasonic waves are transmitted / received only once from the first plurality of elements E1 to En of the array transducer 1 toward the reflection point A in the subject, and element data is acquired in step S3. . That is, ultrasonic waves are transmitted from the first plurality of elements E1 to En to the reflection point A according to the drive signal supplied from the transmission circuit 2, and from the elements E1 to En that have received the ultrasonic echoes from the reflection point A. A reception signal is output to the reception circuit 3, element data is generated by the reception circuit 3, and sequentially stored in the element data memory 7.

Next, in step S3, one of the second plurality of elements having received the ultrasonic echo passing through the region R1A other than the region of interest R2A by the time difference calculation unit 21 is used as a reference device, and other than the reference device. The element is set as a plurality of measurement elements, and comparison is performed between element data corresponding to the reference element and element data corresponding to the plurality of measurement elements, and a plurality of first time differences ΔT1 are calculated. . In addition, among a plurality of elements that have received an ultrasonic echo passing through the region of interest R2A, one element is set as a reference element, and elements other than the reference element are set as a plurality of measurement elements, and elements corresponding to the reference elements A comparison is made between the data and element data corresponding to a plurality of measuring elements, and a plurality of second time differences ΔT2 are calculated.
Further, in step S13, based on the geometric arrangement of the second plurality of elements that have received the ultrasonic echoes passing through the region R1A and the plurality of first time differences ΔT1, the sound speed calculation unit 22 performs a plurality of operations in the region R1A. The individual sound velocity Va is calculated. Based on the plurality of individual sound speeds Va calculated in this way, the total sound speed V1 in the region R1A is determined by the total sound speed determination unit 23 in step S5.

Thereafter, in step S14, based on the geometric arrangement of the plurality of elements that have received the ultrasonic echoes passing through the region of interest R2A and the plurality of second time differences ΔT2, the sound speed calculation unit 22 performs a plurality of operations in the region of interest R2A. The individual sound speed Vb is calculated. Based on the plurality of individual sound speeds Vb calculated in this manner, the local sound speed V2 in the region of interest R2A is determined by the local sound speed determination unit 25 in step S15.

Further, a B-mode image signal is generated by the image generator 4 based on the element data generated by the receiving circuit 3 by scanning the ultrasonic beam from the first plurality of elements E1 to En of the array transducer 1. The B-mode image signal is output to the display control unit 5 and the ultrasonic image is displayed on the display unit 6.
The total sound speed V1 and the local sound speed V2 determined by the sound speed quantification unit 8 are output to the image generation unit 4, and the values of the total sound speed V1 and the local sound speed V2 are displayed on the display unit 6 together with the ultrasonic image. Only the value of the local sound speed V2 may be displayed instead of both the overall sound speed V1 and the local sound speed V2.

Further, based on the total sound speed V1 and the local sound speed V2 output from the sound speed quantification unit 8, the image generation unit 4 generates a B-mode image signal using the total sound speed V1 for the region R1A other than the region of interest R2A. For the region of interest R2A, a B-mode image signal using the local sound speed V2 can also be generated. In this way, it is possible to generate a high-quality ultrasonic image in the region R1A other than the region of interest R2A and also in the region of interest R2A.

Embodiment 4
In Embodiment 3 described above, the total sound velocity V1 and the local sound velocity V2 are quantified by transmitting and receiving ultrasonic waves only once toward one reflection point A in the subject. Thus, it is possible to quantify the total sound speed V1 and the local sound speed V2 by transmitting and receiving ultrasonic waves once each.
For example, as shown in FIG. 14, element data obtained by transmitting and receiving ultrasonic waves once toward the reflection point Av on one scanning line Cv, and as shown in FIG. 15, the scanning line Element data acquired by performing ultrasonic wave transmission / reception once toward the reflection point Aw on the scanning line Cw different from Cv is used.

As shown in the flowchart of FIG. 24, in the fourth embodiment, the region of interest R2A is set by the region of interest setting unit 17 in step S12, and the first plurality of elements E1 to E1 of the array transducer 1 are set in step S1. Ultrasonic waves are transmitted and received only once from En to the reflection point Av in the subject, and element data is acquired and stored in the element data memory 7 in step S2.
In subsequent step S10, it is determined whether or not the transmission / reception of ultrasonic waves to / from the plurality of set reflection points is completed. If it is determined that the transmission / reception is not completed, the reflection point is changed in step S11, and then the step is performed. S1 and S2 are repeated. That is, instead of the scanning line Cv to the scanning line Cw, ultrasonic waves are transmitted / received only once toward the reflection point Aw, and element data is acquired and stored in the element data memory 7.

If it is determined in step S10 that transmission / reception of ultrasonic waves to all reflection points has been completed, the reflection point Av in the region R1A other than the region of interest R2A is detected by the time difference calculation unit 21 of the sound velocity quantification unit 8A in step S3. The element data corresponding to the reference element and the element data corresponding to the plurality of measurement elements are respectively compared with Aw and Aw to calculate a plurality of first time differences ΔT1. Further, in the region of interest R2A, the element data corresponding to the reference element and the element data corresponding to the plurality of measurement elements are respectively compared with the reflection points Av and Aw, and a plurality of second time differences ΔT2 are compared. Is calculated.
In subsequent step S13, the sound speed calculation unit 22 determines the reflection points Av and Aw based on the geometrical arrangement of the second plurality of elements that receive the ultrasonic echo passing through the region R1A and the plurality of first time differences ΔT1. Corresponding to each, a plurality of individual sound velocities Va in the region R1A are calculated.
Further, in step S5, the overall sound speed determination unit 23 creates a histogram of a plurality of individual sound speeds Va corresponding to each of the reflection points Av and Aw, and the individual sound speed Va having the highest frequency is the overall sound speed V1 in the region R1A. As determined.

Thereafter, in step S14, each of the reflection points Av and Aw is determined based on the geometrical arrangement of the plurality of elements and the plurality of second time differences ΔT2 received by the sound speed calculation unit 22 through the region of interest R2A. Corresponding to the plurality of individual sound velocities Vb in the region of interest R2A. Further, in step S15, the local sound speed determination unit 25 creates a histogram of a plurality of individual sound speeds Vb corresponding to each of the reflection points Av and Aw, and the individual sound speed Vb having the highest frequency is the local sound speed in the region of interest R2A. Determined as V2.
Thus, by transmitting / receiving ultrasonic waves to / from a plurality of reflection points to acquire element data, it is possible to quantify the total sound speed V1 and the local sound speed V2 with higher accuracy.

Embodiment 5
In the above third and fourth embodiments, when the region of interest R2A is set by the region of interest setting unit 17, both the overall sound velocity V1 in the region R1A other than the region of interest R2A and the local sound velocity V2 in the region of interest R2A are determined. However, according to the size of the region of interest R2A set by the region-of-interest setting unit 17, the sound speed to be quantified can be selected from the overall sound speed V1 and the local sound speed V2.
The ultrasonic diagnostic apparatus according to Embodiment 5 quantifies both the total sound speed V1 and the local sound speed V2 when both the length in the scanning direction and the length in the depth direction of the region of interest R2A are larger than the set values. When at least one of the length in the scanning direction and the length in the depth direction of the region of interest R2A is equal to or less than the set value, only the total sound speed V1 is quantified without quantifying the local sound speed V2. is there.

FIG. 25 shows the operation of the ultrasonic diagnostic apparatus according to the fifth embodiment.
First, in step S12, the region of interest R2A is set by the region of interest setting unit 17, and in step S1, the first plurality of elements E1 to En of the array transducer 1 is directed only once toward the reflection point A in the subject. Ultrasonic waves are transmitted and received, and element data is acquired and stored in the element data memory 7 in step S2.

Thereafter, in step S16, the controller 9 determines whether or not a condition Y1 regarding the length in the scanning direction and the length in the depth direction of the region of interest R2A is satisfied. The condition Y1 is a condition that both the length in the scanning direction and the length in the depth direction of the region of interest R2A are larger than a preset set value. The set value can be, for example, a length of 1/10 of the arrangement pitch of the first plurality of elements E1 to En of the array transducer 1. When the length in the scanning direction and the length in the depth direction of the region of interest R2A are equal to or smaller than such set values, the propagation time of the ultrasonic echo that reaches the element of the array transducer 1 from the reflection point through the region of interest R2A The influence of the region of interest R2A on is too small, and it becomes difficult to accurately quantify the local sound speed V2 in the region of interest R2A.

Therefore, when it is determined in step S16 that the length in the scanning direction and the length in the depth direction of the region of interest R2A are both greater than the set value and the condition Y1 is satisfied, the process proceeds to step S17, where the overall sound speed V1 and the local sound speed V1 A quantification process 100 for quantifying both the sound speeds V2 is executed. On the other hand, it is determined that the condition Y1 is not satisfied because at least one of the length in the scanning direction and the length in the depth direction of the region of interest R2A is equal to or less than a set value. If so, the process proceeds to step S18, and a quantification process 200 for quantifying only the overall sound speed V1 is executed.

In the quantification process 100, as shown in FIG. 26, in step S3, the time difference calculation unit 21 uses the time difference calculation unit 21 to store the element data stored in the element data memory 7 in the region R1A other than the region of interest R2A. A plurality of first time differences ΔT1 are calculated based on element data corresponding to the second plurality of elements that have received the acoustic echoes, and among the element data stored in the element data memory 7, the region of interest R2A A plurality of second time differences ΔT2 are calculated based on element data corresponding to the plurality of elements that have received the ultrasonic echoes passing through. In subsequent step S13, the sound velocity calculation unit 22 calculates a plurality of individual sound velocities Va in the region R1A. In step S5, the overall sound speed determination unit 23 calculates the overall sound speed V1 in the region R1A based on the plurality of individual sound velocities Va. It is determined. Further, in step S14, the sound speed calculation unit 22 calculates a plurality of individual sound speeds Vb in the region of interest R2A. In step S15, the local sound speed determination unit 25 calculates the local sound speeds Vb in the region of interest R2A based on the plurality of individual sound speeds Vb. The speed of sound V2 is determined.

On the other hand, in the quantification process 200, as shown in FIG. 27, the time difference calculation unit 21 passes the region R1A other than the region of interest R2A among the element data stored in the element data memory 7 in step S3. A plurality of first time differences ΔT1 are calculated based on element data corresponding to the second plurality of elements that have received the ultrasonic echo. In subsequent step S13, the sound velocity calculation unit 22 calculates a plurality of individual sound velocities Va in the region R1A. In step S5, the overall sound speed determination unit 23 calculates the overall sound speed V1 in the region R1A based on the plurality of individual sound velocities Va. The local sound speed V2 in the region of interest R2A is not quantified.

Further, the region of interest R2A set by the region of interest setting unit 17 is long in the scanning direction, and the region of interest among the plurality of straight lines connecting the reflection points in the subject and the first plurality of elements E1 to En of the array transducer 1 When the straight line passing through the region R2A exceeds a predetermined ratio (for example, 80%), there are few elements that have received ultrasonic echoes through the region R1A other than the region of interest R2A, and the overall sound speed V1 of the region R1A is accurately determined. It becomes difficult to quantify.

Therefore, a condition where the straight line passing through the region of interest R2A out of a plurality of straight lines connecting the reflection point and the first plurality of elements E1 to En of the array transducer 1 exceeds a predetermined ratio (for example, 80%) is defined as a condition Y2. As shown in FIG. 28, when it is determined in step S16 that the length in the scanning direction and the length in the depth direction of the region of interest R2A are both larger than the set value and the condition Y1 is satisfied, in the subsequent step S19 Then, the control unit 9 determines whether or not the condition Y2 is satisfied, and when the condition Y2 is satisfied, the process further proceeds to step S20 to execute the quantification process 300 for quantifying only the local sound velocity V2. .
In step S19, the condition is that the straight line passing through the region of interest R2A among the plurality of straight lines connecting the reflection point and the first plurality of elements E1 to En of the array transducer 1 is equal to or less than a predetermined ratio (for example, 80%). When it is determined that Y2 is not established, the process proceeds to step S17, and a quantification process 100 for quantifying both the overall sound speed V1 and the local sound speed V2 is executed.

In the quantification process 300, as shown in FIG. 29, in step S3, the time difference calculation unit 21 receives an ultrasonic echo that passes through the region of interest R2A among the element data stored in the element data memory 7. A plurality of second time differences ΔT2 are calculated based on element data corresponding to the plurality of elements. In subsequent step S14, the sound speed calculation unit 22 calculates a plurality of individual sound speeds Vb in the region of interest R2A. In step S15, the local sound speed determination unit 25 calculates the local sound speed V2 of the region of interest R2A based on the plurality of individual sound speeds Vb. The total sound speed V1 is not quantified.
As in the fifth embodiment, by selecting the sound speed to be quantified from the overall sound speed V1 and the local sound speed V2 according to the size of the area of interest R2A set by the area of interest setting unit 17, the high accuracy Quantification of sound speed is possible.

Similarly, also in the second embodiment in which the total sound speed V1 and the local sound speed V2 are quantified using a plurality of reflection points, depending on the size of the region of interest R2A set by the region of interest setting unit 17, etc. The sound speed to be quantified can be selected from the overall sound speed V1 and the local sound speed V2.
Note that even if the reflection point is changed, the length in the scanning direction and the length in the depth direction of the region of interest R2A do not change. Therefore, the determination in step S16 as to whether or not the condition Y1 is satisfied is determined by a plurality of reflection points. Produces the same result. On the other hand, the ratio of the straight line passing through the region of interest R2A among the plurality of straight lines connecting the reflection point and the first plurality of elements E1 to En of the array transducer 1 varies depending on the position of the reflection point. The determination in step S19 as to whether or not is true may give different results for a plurality of reflection points.

Therefore, among the plurality of reflection points, the region of interest R2A when the condition Y2 in step S19 is not satisfied, that is, when the first plurality of elements E1 to En of the array transducer 1 are connected by a plurality of straight lines. When there is a reflection point where the straight line passing through is a predetermined ratio (for example, 80%) or less, the total sound speed V1 quantified in the quantification process 100 in step S17 with respect to the reflection point other than the region of interest R2A It can be employed as the sound speed of the region R1A.

The control unit 9 determines whether or not the condition Y1 in step S16 is satisfied and whether or not the condition Y2 in step S19 is satisfied. However, the present invention is not limited to this. The local sound speed determination unit 25 can also be configured to make these determinations.

In the first to fifth embodiments described above, the total sound speed V1 and the local sound speed V2 are output using the element data output from the first plurality of elements E1 to En of the array transducer 1, amplified by the receiving circuit 3, and digitized. However, the present invention is not limited to this, and the total sound velocity V1 and the local sound velocity V2 can also be quantified using element data that has been digitized and phase-matched.

1 array transducer, 2 transmission circuit, 3 reception circuit, 4 image generation unit, 5 display control unit, 6 display unit, 7 element data memory, 8, 8A sound velocity quantification unit, 9 control unit, 10 operation unit, 11 storage unit , 12 amplifying unit, 13 AD converting unit, 14 signal processing unit, 15 DSC, 16 image processing unit, 17 region of interest setting unit, 21 time difference calculating unit, 22 sound speed calculating unit, 23 overall sound speed determining unit, 24 off region specifying unit , 25 Local sound velocity determination unit, A, Av, Aw reflection point, B lesion, Cv, Cw scanning line, E1 to En, Ec, Ei, Ek, Es, Et, Er element, Li, Lk, Lt, Lt1, Lt2, Lt3, Ls, Ls1, Ls2, Ls3 distance, V1 overall sound speed, V2 local sound speed, Va, Vb individual sound speed, R1 overall area, R1A interest A region other than the frequency, R2 out area, R2A region of interest

Claims

An ultrasonic diagnostic apparatus that transmits an ultrasonic beam toward an object from an array transducer in which a plurality of first elements are arranged, receives an ultrasonic echo from the object, and performs an ultrasonic diagnosis,
A plurality of element data output from the first plurality of elements that have received an ultrasonic echo reflected by the reflection point in response to transmission of an ultrasonic beam toward the reflection point in the subject are stored. Element data memory;
Element data corresponding to a reference element that is one element of the first plurality of elements, and a plurality of measurement elements that are a plurality of elements other than the reference element among the first plurality of elements A time difference calculation unit for calculating a plurality of time differences between a plurality of element data corresponding to
The plurality of measurement elements based on the distance from the reflection point to the reference element, the distance from the reflection point to the plurality of measurement elements, and the plurality of time differences calculated by the time difference calculation unit A sound speed calculation unit for calculating a plurality of individual sound speeds corresponding to
An ultrasonic diagnostic apparatus comprising: an overall sound speed determination unit that determines an overall sound speed based on the plurality of individual sound speeds calculated by the sound speed calculation unit.
Whether or not there is an individual sound speed in which the absolute value of the difference from the overall sound speed determined by the overall sound speed determination section exceeds a speed threshold value among the plurality of individual sound speeds calculated by the sound speed calculation section And an outlier specifying unit that specifies an area between the element corresponding to the individual sound speed at which the absolute value of the difference exceeds the velocity threshold and the reflection point as an outlier. Ultrasonic diagnostic equipment.
Based on the distance from the reflection point to the two or more elements that have received the ultrasonic echo passing through the outlier, and the time difference calculated by the time difference calculation unit for the two or more elements. The ultrasonic diagnostic apparatus according to claim 2, further comprising a local sound speed determining unit that determines a local sound speed in the outlier region from at least one individual sound speed calculated by the sound speed calculating unit.
An image generation unit that generates an ultrasound image based on the plurality of element data output from the first plurality of elements;
A region-of-interest setting unit for setting a region of interest on the ultrasound image,
The time difference calculator is configured to change one element of the second plurality of elements that has received the ultrasonic echo passing through a region other than the region of interest among the first plurality of elements, the reference element, The ultrasonic diagnostic apparatus according to claim 1, wherein the plurality of time differences are calculated using an element other than the reference element among the plurality of elements as the measurement element.
Based on the distance from the reflection point to two or more elements that have received the ultrasonic echo passing through the region of interest, and the time difference calculated by the time difference calculation unit for the two or more elements The ultrasonic diagnostic apparatus according to claim 4, further comprising a local sound speed determination unit that determines a local sound speed in the region of interest from at least one individual sound speed calculated by the sound speed calculation unit.
The total sound speed determination unit is set by the region of interest setting unit when at least one of the length in the scanning direction and the length in the depth direction of the region of interest set by the region of interest setting unit is a set value or less. The length of the region of interest in the scanning direction and the length of the depth direction are both larger than the set value and pass through the region of interest among a plurality of straight lines connecting the reflection point and the first plurality of elements. The ultrasonic diagnostic apparatus according to claim 5, wherein the overall sound velocity is determined only when a straight line is equal to or less than a predetermined ratio.
The local sound speed determination unit determines the local sound speed only when the length in the scanning direction and the length in the depth direction of the region of interest set by the region of interest setting unit are both larger than the set value. 6. The ultrasonic diagnostic apparatus according to 6.
The ultrasonic diagnostic apparatus according to any one of claims 4 to 7, wherein the region-of-interest setting unit sets the region of interest according to a user designation.
The ultrasonic diagnostic apparatus according to any one of claims 4 to 7, wherein the region-of-interest setting unit automatically sets the region of interest by performing image analysis on the ultrasonic image.
The element data memory is configured to transmit a plurality of output points from the first plurality of elements to the plurality of reflection points by transmitting an ultrasonic beam toward the plurality of reflection points located on different scanning lines. Save element data,
The time difference calculation unit calculates the plurality of time differences for each of the plurality of reflection points,
The sound speed calculating unit calculates the plurality of individual sound speeds for the plurality of reflection points,
The ultrasonic diagnostic apparatus according to claim 3, wherein the overall sound speed determination unit determines the overall sound speed based on the plurality of individual sound speeds respectively calculated for the plurality of reflection points by the sound speed calculation unit.
The local sound speed determination unit includes a distance from each of the plurality of reflection points to two or more elements that have received the ultrasonic echo passing through the outlier region, each of the plurality of reflection points, and the two or more of the plurality of reflection points. The supersonic wave according to claim 10, wherein a local sound speed in the outlier region is determined from a plurality of sound speeds calculated by the sound speed calculating part based on a plurality of time differences calculated by the time difference calculating part with respect to an element. Ultrasonic diagnostic equipment.
The element data memory is configured to transmit a plurality of output points from the second plurality of elements to the plurality of reflection points by transmitting an ultrasonic beam toward the plurality of reflection points located on different scanning lines. Save element data,
The time difference calculation unit calculates the plurality of time differences for each of the plurality of reflection points,
The sound speed calculating unit calculates the plurality of individual sound speeds for the plurality of reflection points,
The total sound speed determination unit determines the total sound speed based on the plurality of individual sound speeds calculated for the plurality of reflection points by the sound speed calculation unit, respectively. Ultrasound diagnostic equipment.
The local sound speed determination unit includes a distance from each of the plurality of reflection points to two or more elements that have received the ultrasonic echo passing through the region of interest, each of the plurality of reflection points, and the two or more of the plurality of reflection points. The supersonic wave according to claim 12, wherein a local sound speed in the region of interest is determined from a plurality of sound speeds calculated by the sound speed calculating part based on a plurality of time differences calculated by the time difference calculating part with respect to an element. Ultrasonic diagnostic equipment.
A plurality of element data output from the first plurality of elements of the array transducer that has received the ultrasonic echo reflected by the reflection point corresponding to the transmission of the ultrasonic beam toward the reflection point in the subject is stored. And
Element data corresponding to a reference element that is one element of the first plurality of elements, and a plurality of measurement elements that are a plurality of elements other than the reference element among the first plurality of elements Calculate multiple time differences between multiple element data corresponding to
Based on the distance from the reflection point to the reference element, the distance from the reflection point to the plurality of measurement elements, and the calculated time differences, a plurality of measurement elements corresponding to the plurality of measurement elements. Calculate individual sound speeds,
A sound speed quantification method for determining an overall sound speed based on the calculated individual sound speeds.