WO2012011414A1

WO2012011414A1 - Ultrasonic diagnostic device, method for operating ultrasonic diagnostic device, and operation program for ultrasonic diagnostic device

Info

Publication number: WO2012011414A1
Application number: PCT/JP2011/065910
Authority: WO
Inventors: 浩仲宮木; 弘孝江田; 裕雅野口; 忠明神原; 安広和田
Original assignee: オリンパスメディカルシステムズ株式会社
Priority date: 2010-07-20
Filing date: 2011-07-12
Publication date: 2012-01-26
Also published as: JPWO2012011414A1

Abstract

Disclosed is an ultrasonic diagnostic device that diagnoses tissue characteristics in a subject based on received ultrasonic waves, by sending ultrasonic waves to a diagnostic subject and also receiving the ultrasonic waves that have been reflected by the subject. The ultrasonic diagnostic device extracts frequency characteristics of a frequency spectrum in a prescribed area in a subject by approximating a frequency spectrum obtained by analyzing the frequency of the received ultrasonic waves and determines the tissue characteristics of a prescribed area in a subject by using these frequency characteristics and the frequency characteristics of a frequency spectrum extracted based on the tissue characteristics of a plurality of known subjects and ultrasonic waves reflected from the plurality of known subjects.

Description

Ultrasonic diagnostic apparatus, method for operating ultrasonic diagnostic apparatus, and operation program for ultrasonic diagnostic apparatus

The present invention relates to an ultrasonic diagnostic apparatus for diagnosing a tissue property of a specimen using ultrasonic waves, an operating method of the ultrasonic diagnostic apparatus, and an operating program for the ultrasonic diagnostic apparatus.

Conventionally, a technique called ultrasonic elastography is known as an inspection technique for breast cancer and the like using ultrasonic waves (see, for example, Patent Document 1). Ultrasonic elastography is a technique that utilizes the fact that the hardness of cancer and tumor tissue in a living body varies depending on the progress of the disease and the living body. In this technique, the amount of strain and elastic modulus of the biological tissue at the examination location are measured using ultrasound while the examination location is pressed from the outside, and the measurement result is displayed as a tomographic image.

International Publication No. 2005/122906

However, the ultrasonic elastography described above has a problem in that the pressure applied to the lower part of a blood vessel or a lymph vessel is difficult to be transmitted. Therefore, when a tumor is formed in the vicinity of the blood vessel, the boundary of the tumor is unclear and it is difficult to distinguish the invasion of the tumor into the blood vessel. As described above, in ultrasonic elastography, there are cases in which it is not possible to accurately distinguish tissue properties.

Also, ultrasonic elastography has a problem in that the reliability of measurement results is low because individual differences are likely to occur in the pressure and compression speed when the examiner compresses the examination location.

The present invention has been made in view of the above, and enables an ultrasonic diagnostic apparatus and an ultrasonic diagnostic apparatus capable of accurately distinguishing tissue properties and improving the reliability of measurement results. It is an object to provide an operating method and an operating program for an ultrasonic diagnostic apparatus.

In order to solve the above-described problems and achieve the object, an ultrasonic diagnostic apparatus according to the present invention transmits ultrasonic waves to a specimen to be diagnosed and receives ultrasonic waves reflected by the specimen. An ultrasonic diagnostic apparatus for diagnosing the tissue characteristics of the specimen based on the received ultrasound, the frequency analyzer calculating the frequency spectrum by analyzing the frequency of the received ultrasound, and the frequency analyzer calculating A feature quantity extraction unit for extracting the feature quantity of the frequency spectrum by approximating the frequency spectrum, and the feature quantity of the frequency spectrum extracted based on the ultrasonic waves respectively reflected by the plurality of known specimens. A storage unit that stores information in association with tissue properties of known samples, and a feature that the storage unit stores in association with tissue properties of the plurality of known samples. And characterized in that and a tissue characterization determining unit determines the tissue properties of a predetermined area of the specimen by using a feature quantity the feature amount extraction unit and extracted.

The ultrasonic diagnostic apparatus according to the present invention is characterized in that, in the above invention, the feature amount extraction unit approximates the frequency spectrum by a polynomial by regression analysis.

Further, in the ultrasonic diagnostic apparatus according to the present invention, in the above invention, the feature amount extraction unit approximates the frequency spectrum with a linear expression, the slope of the linear expression, the intercept of the linear expression, and the frequency spectrum. A plurality of feature quantities including a frequency included in the frequency band, an intensity determined by the slope and the intercept are extracted.

Further, in the ultrasonic diagnostic apparatus according to the present invention, in the above invention, the storage unit stores an average of each feature amount in a group classified for each tissue property with respect to the plurality of known samples, and the tissue property The determination unit sets a feature amount space including at least one of the plurality of feature amounts as a component, and sets the feature amount constituting the component of the feature amount space among the feature amounts of the frequency spectrum in the predetermined region of the specimen. A specimen average point having an average as coordinates of the feature quantity space, and an average of feature quantities constituting components of the feature quantity space among the feature quantities in the group of the plurality of known specimens as coordinates of the feature quantity space The tissue property of the specimen is determined based on the distance in the feature amount space with the known specimen average point.

In the ultrasonic diagnostic apparatus according to the present invention, in the above invention, the tissue property determination unit corresponds to a group in which a distance in the feature amount space between the specimen average point and the known specimen average point is minimum. The tissue property is the tissue property of the specimen.

In the ultrasonic diagnostic apparatus according to the present invention as set forth in the invention described above, the tissue property determination unit has a larger value as a distance in the feature amount space between the specimen average point and the known specimen average point is smaller. The probability that the sum of the values corresponding to all the distances is 1 is calculated with respect to all the distances, whereby the tissue properties of the specimen are determined probabilistically.

Further, in the ultrasonic diagnostic apparatus according to the present invention, in the above invention, the tissue property determination unit includes a feature in a population obtained by adding a feature amount of the sample to a group classified for each tissue property in the plurality of known samples. A standard deviation of the quantity is calculated, and a tissue characteristic corresponding to a group having a characteristic quantity having a minimum difference between the standard deviation and the standard deviation of the characteristic quantity in the group is defined as the tissue characteristic of the specimen. .

Further, the ultrasonic diagnostic apparatus according to the present invention, in the above invention, generates visual information corresponding to the feature amount of the specimen, the generated visual information, an image generated based on the received ultrasonic wave, and A determination result display image data generation unit for generating determination result display image data for displaying the determination result of the tissue property of the predetermined region of the specimen by using the result determined by the tissue property determination unit; To do.

In the ultrasonic diagnostic apparatus according to the present invention as set forth in the invention described above, the visual information is a variable constituting a color space.

In addition, the operation method of the ultrasonic diagnostic apparatus according to the present invention includes transmitting the ultrasonic wave to the specimen to be diagnosed and receiving the ultrasonic wave reflected by the specimen, whereby the specimen based on the received ultrasonic wave The method of operating an ultrasonic diagnostic apparatus for diagnosing the tissue properties of a frequency analysis step of calculating a frequency spectrum by a frequency analysis unit by analyzing the frequency of the received ultrasonic wave, and the frequency calculated in the frequency analysis step A feature amount extraction step for extracting a feature amount of the frequency spectrum by approximating the spectrum by a feature amount extraction unit, and a feature amount of the frequency spectrum extracted based on ultrasonic waves respectively reflected by a plurality of known specimens The feature amount read from the storage unit that stores the plurality of known specimens in association with the tissue properties and the feature Characterized by having a a tissue property determining step of determining the tissue characterization determining unit tissue characterization of a predetermined area of said specimen by using the feature information extracted in an amount extraction step.

In addition, the operation program of the ultrasonic diagnostic apparatus according to the present invention includes transmitting the ultrasonic wave to the sample to be diagnosed and receiving the ultrasonic wave reflected by the sample, whereby the sample based on the received ultrasonic wave A frequency analysis step of calculating a frequency spectrum by a frequency analysis unit by analyzing the frequency of the received ultrasonic wave, and approximating the frequency spectrum calculated in the frequency analysis step to an ultrasonic diagnostic apparatus for diagnosing the tissue property of A feature amount extraction step for extracting a feature amount of the frequency spectrum by a feature amount extraction unit; a feature amount of the frequency spectrum extracted based on ultrasonic waves respectively reflected by a plurality of known specimens; The feature amount read from the storage unit that is stored in association with the property and the feature amount extraction step Characterized in that to perform tissue characterization determining step determines the tissue characterization determining unit tissue characterization of a predetermined area of said specimen by in using the extracted feature quantity.

According to the present invention, a frequency spectrum characteristic amount in a predetermined region of the specimen is extracted by approximating a frequency spectrum obtained by analyzing the frequency of the received ultrasonic wave, and a plurality of known specimens are used while using this characteristic quantity. The tissue characteristics of a predetermined region of the specimen are determined by using the feature quantity of the frequency spectrum extracted based on the ultrasonic wave reflected by the tissue. Can be clearly distinguished. Therefore, it is possible to accurately distinguish the tissue properties and improve the reliability of the measurement results.

FIG. 1 is a block diagram showing the configuration of the ultrasonic diagnostic apparatus according to Embodiment 1 of the present invention. FIG. 2 is a flowchart showing an outline of processing of the ultrasonic diagnostic apparatus according to Embodiment 1 of the present invention. FIG. 3 is a diagram showing a display example of a B-mode image on the display unit of the ultrasonic diagnostic apparatus according to Embodiment 1 of the present invention. FIG. 4 is a flowchart showing an outline of processing performed by the frequency analysis unit of the ultrasonic diagnostic apparatus according to Embodiment 1 of the present invention. FIG. 5 is a diagram schematically showing a data array of one sound ray. FIG. 6 is a diagram illustrating an example (first example) of a frequency spectrum calculated by the frequency analysis unit of the ultrasonic diagnostic apparatus according to Embodiment 1 of the present invention. FIG. 7 is a diagram illustrating an example (second example) of a frequency spectrum calculated by the frequency analysis unit of the ultrasonic diagnostic apparatus according to Embodiment 1 of the present invention. FIG. 8 is a flowchart showing an outline of processing performed by the tissue property determination unit of the ultrasonic diagnostic apparatus according to Embodiment 1 of the present invention. FIG. 9 is a diagram illustrating an example of a feature amount space set by the tissue property determination unit of the ultrasonic diagnostic apparatus according to Embodiment 1 of the present invention. FIG. 10 is a diagram illustrating a display example of a determination result display image displayed by the display unit of the ultrasonic diagnostic apparatus according to Embodiment 1 of the present invention. FIG. 11 is a diagram illustrating another display example of the determination result display image displayed by the display unit of the ultrasonic diagnostic apparatus according to Embodiment 1 of the present invention. FIG. 12 is a diagram illustrating an overview of the tissue property determination process performed by the tissue property determination unit of the ultrasonic diagnostic apparatus according to Embodiment 4 of the present invention.

DETAILED DESCRIPTION Hereinafter, embodiments for carrying out the present invention (hereinafter referred to as “embodiments”) will be described with reference to the accompanying drawings.

(Embodiment 1)
FIG. 1 is a block diagram showing the configuration of the ultrasonic diagnostic apparatus according to Embodiment 1 of the present invention. An ultrasonic diagnostic apparatus 1 shown in FIG. 1 is an apparatus for diagnosing the tissue properties of a specimen to be diagnosed using ultrasonic waves.

The ultrasonic diagnostic apparatus 1 transmits and receives electrical signals between the ultrasonic probe 2 that outputs an ultrasonic pulse to the outside and receives an ultrasonic echo reflected from the outside, and the ultrasonic probe 2. Transmitting / receiving unit 3 for performing the calculation, calculation unit 4 for performing a predetermined calculation on the electrical echo signal converted from the ultrasonic echo, and generation of image data corresponding to the electrical echo signal converted from the ultrasonic echo An image processing unit 5 to be performed, an interface such as a keyboard, a mouse, a touch panel, and the like. The image processing unit 5 is realized by using an input unit 6 that receives input of various information and a display panel made of liquid crystal or organic EL. 5, a display unit 7 that displays various types of information including the image generated, a storage unit 8 that stores various types of information including information related to the tissue properties of the known specimen, and a control unit that controls the operation of the ultrasonic diagnostic apparatus 1. And, equipped with a.

The ultrasonic probe 2 converts an electrical pulse signal received from the transmission / reception unit 3 into an ultrasonic pulse (acoustic pulse signal), and converts an ultrasonic echo reflected by an external specimen into an electrical echo signal. A signal conversion unit 21 for conversion is included. The ultrasonic probe 2 may be one that mechanically scans an ultrasonic transducer, or one that electronically scans a plurality of ultrasonic transducers.

The transmitting / receiving unit 3 is electrically connected to the ultrasonic probe 2, transmits a pulse signal to the ultrasonic probe 2, and receives an echo signal from the ultrasonic probe 2. Specifically, the transmission / reception unit 3 generates a pulse signal based on a preset waveform and transmission timing, and transmits the generated pulse signal to the ultrasound probe 2. Further, the transmission / reception unit 3 performs processing such as amplification and filtering on the received echo signal, and then performs A / D conversion to generate and output a digital RF signal. When the ultrasonic probe 2 is to electronically scan a plurality of ultrasonic transducers, the transmission / reception unit 3 has a multi-channel circuit for beam synthesis corresponding to the plurality of ultrasonic transducers.

The calculation unit 4 is obtained by a frequency analysis unit 41 that performs a frequency analysis of an echo signal by performing a fast Fourier transform (FFT) on the digital RF signal output from the transmission / reception unit 3, and a frequency analysis performed by the frequency analysis unit 41. The feature quantity extraction unit 42 that extracts the feature quantity of the frequency spectrum by approximating the obtained frequency spectrum (power spectrum), and the tissue quantity of the predetermined region of the specimen are determined using the feature quantity extracted by the feature quantity extraction unit 42 And a tissue property determination unit 43.

The frequency analysis unit 41 calculates a frequency spectrum by performing a fast Fourier transform on an FFT data group having a predetermined amount of data for each sound ray (line data). The frequency spectrum shows different tendencies depending on the tissue properties of the specimen. This is because the frequency spectrum has a correlation with the size, density, acoustic impedance, and the like of the specimen as a scatterer that scatters ultrasonic waves.

The feature quantity extraction unit 42 approximates the frequency spectrum with a linear expression by regression analysis, and extracts a feature quantity that characterizes the approximated primary expression. Specifically, the feature quantity extraction unit 42 calculates the slope a and the intercept b of the linear expression by regression analysis, and at the same time the intensity at the center frequency f _MID = (f _LOW + f _HIGH ) / 2 in the frequency spectrum. Mid-band fit) c = af _MID + b is calculated. Here, “intensity” refers to any of parameters such as voltage, power, sound pressure, and acoustic energy. Among these, the inclination a has a correlation with the size of the ultrasonic scatterer, and it is generally considered that the larger the scatterer, the lower the inclination. The intercept b has a correlation with the size of the scatterer, the difference in acoustic impedance, the density (concentration) of the scatterer, and the like. The intensity c is an indirect parameter derived from the slope a and the intercept b, and gives the spectral intensity at the center in the effective frequency band. Therefore, the intensity c is considered to have a certain degree of correlation with the brightness of the B-mode image in addition to the size of the scatterer, the difference in acoustic impedance, and the density of the scatterer. Note that the approximate polynomial calculated by the feature amount extraction unit 42 is not limited to a linear expression, and it is possible to use a quadratic or higher approximate polynomial.

The tissue property determination unit 43 calculates the average and standard deviation of the feature amounts of the frequency spectrum extracted by the feature amount extraction unit 42 for each feature amount. The tissue property determination unit 43 determines the tissue property of a predetermined region of the sample by using the calculated average and standard deviation and the average and standard deviation of the feature amounts of the frequency spectrum of the known sample stored in the storage unit 8. . The “predetermined region” referred to here is a region in the image (hereinafter referred to as “region of interest”) designated by the input unit 6 by the operator of the ultrasonic diagnostic apparatus 1 who viewed the image generated by the image processing unit 5. That is. In addition, the “tissue property” referred to here is, for example, any of cancer, endocrine tumor, mucinous tumor, normal tissue, vascular and the like. When the specimen is pancreas, the tissue properties include chronic pancreatitis, autoimmune pancreatitis and the like.

The average and standard deviation of the feature values calculated by the tissue characterization determining unit 43 is a systematic change such as a change in cell level such as nuclear enlargement or anomaly, an increase in fibers in the stroma, or a replacement of the real tissue with fibers. This is a unique value depending on the tissue properties. Therefore, by using such an average and standard deviation of the feature amounts, it is possible to accurately determine the tissue properties of a predetermined region of the specimen.

The image processing unit 5 outputs the B-mode image data generating unit 51 that generates the B-mode image data to be displayed by converting the amplitude of the echo signal into the luminance, the B-mode image data generating unit 51, and the calculation unit 4, respectively. A determination result display image data generation unit 52 that generates determination result display image data for displaying the determination result of the tissue property of the region of interest and information related to the determination result using the data.

The B-mode image data generation unit 51 performs signal processing using a known technique such as a bandpass filter, logarithmic conversion, gain processing, contrast processing, and the like on the digital signal, and also according to the image display range on the display unit 7. B-mode image data is generated by thinning out data in accordance with the data step width determined in advance.

The determination result display image data generation unit 52 uses the B mode image data generated by the B mode image data generation unit 51, the feature amount calculated by the feature amount extraction unit 42, and the determination result determined by the tissue property determination unit 43. Thus, determination result display image data including the determination result of the tissue property of the region of interest and the tissue property emphasized image that emphasizes the tissue property is generated.

The storage unit 8 includes a known sample information storage unit 81 that stores information on known samples, and a window function storage unit 82 that stores a window function used in the frequency analysis process performed by the frequency analysis unit 41. The known specimen information storage unit 81 stores the characteristic amount of the frequency spectrum extracted by the frequency analysis for the known specimen in association with the tissue property of the known specimen. In addition, the known specimen information storage unit 81 uses the average and standard deviation calculated for each group classified for each tissue property of the known specimen with respect to the feature quantity of the frequency spectrum related to the known specimen. It is memorized with all the data. The information on the known specimen stored in the known specimen information storage unit 81 is desirably information with high reliability related to the tissue properties. The window function storage unit 82 stores at least one of window functions such as Hamming, anning, and Blackman. The storage unit 8 includes a ROM in which an operation program for the ultrasonic diagnostic apparatus according to the first embodiment, a program for starting a predetermined OS, and the like are stored in advance, and a RAM in which calculation parameters and data for each process are stored. It is realized using.

Components other than the ultrasound probe 2 of the ultrasound diagnostic apparatus 1 having the above functional configuration are realized using a computer having a CPU having a calculation and control function. The CPU provided in the ultrasonic diagnostic apparatus 1 reads out various programs including information stored and stored in the storage unit 8 and the above-described operation program of the ultrasonic diagnostic apparatus from the storage unit 8, so that the ultrasonic according to the first embodiment is obtained. Arithmetic processing related to the operation method of the ultrasonic diagnostic apparatus is executed.

Note that the operation program of the ultrasonic diagnostic apparatus according to the first embodiment may be recorded on a computer-readable recording medium such as a hard disk, a flash memory, a CD-ROM, a DVD-ROM, or a flexible disk and widely distributed. Is possible.

FIG. 2 is a flowchart showing an outline of processing of the ultrasonic diagnostic apparatus 1 having the above configuration. In FIG. 2, the ultrasound diagnostic apparatus 1 first measures a new specimen by the ultrasound probe 2 (step S1). Thereafter, the B mode image data generation unit 51 generates B mode image data (step S2).

Subsequently, the control unit 9 controls the display unit 7 to display a B mode image corresponding to the B mode image data generated by the B mode image data generation unit 51 (step S3). FIG. 3 is a diagram illustrating a display example of the B-mode image on the display unit 7. A B-mode image 100 shown in the figure is a grayscale image in which values of red (R), green (G), and blue (B), which are variables when the RGB color system is adopted as a color space, are matched. .

Thereafter, when a region of interest is set via the input unit 6 (step S4: Yes), the frequency analysis unit 41 calculates a frequency spectrum by performing frequency analysis by FFT calculation (step S5). In this step S5, it is also possible to set the entire region of the image as the region of interest. On the other hand, when the region of interest has not been set (step S4: No), when an instruction to end the process is input by the input unit 6 (step S6: Yes), the ultrasound diagnostic apparatus 1 ends the process. . On the other hand, when the region of interest is not designated (step S4: No), when the instruction to end the process is not input by the input unit 6 in step S6 (step S6: No), the ultrasonic diagnostic apparatus 1 Return to step S4.

Here, the process (step S5) performed by the frequency analysis unit 41 will be described in detail with reference to the flowchart shown in FIG. First, the frequency analysis unit 41 sets the sound ray number L of the sound ray to be analyzed first as an initial value L ₀ (step S11). The initial value L ₀ may be given, for example, to a sound ray that is first received by the transmission / reception unit 3, or for a sound ray corresponding to one of the left and right boundary positions of the region of interest set by the input unit 6. May be given.

Subsequently, the frequency analysis unit 41 calculates all frequency spectra on one sound ray. First, the frequency analysis unit 41 sets an initial value Z ₀ of a data position Z that represents a series of data groups (FFT data group) acquired for FFT calculation (step S12). FIG. 5 is a diagram schematically showing a data array of one sound ray. In the sound ray LD shown in the figure, a white or black rectangle means one piece of data. The sound ray LD is discretized at a time interval corresponding to a sampling frequency (for example, 50 MHz) in A / D conversion performed by the transmission / reception unit 3. FIG. 5 shows a case where the first data of the sound ray LD is set as the initial value Z ₀ of the data position Z. Note that FIG. 5 is merely an example, and the position of the initial value Z ₀ can be arbitrarily set. For example, the data position Z corresponding to the upper end position of the region of interest may be set as the initial value Z ₀ .

Thereafter, the frequency analysis unit 41 acquires the FFT data group at the data position Z (step S13), and causes the window function stored in the window function storage unit 82 to act on the acquired FFT data group (step S14). In this way, by applying the window function to the FFT data group, it is possible to avoid the FFT data group from becoming discontinuous at the boundary and to prevent the occurrence of artifacts.

Subsequently, the frequency analysis unit 41 determines whether or not the FFT data group at the data position Z is a normal data group (step S15). Here, the FFT data group needs to have a power number of 2 data. Hereinafter, the number of data in the FFT data group is 2 ⁿ (n is a positive integer). That the FFT data group is normal means that the data position Z is the 2 ^n-1 th position from the front in the FFT data group. In other words, the normal FFT data group means that there are 2 ⁿ⁻¹ −1 (= N) data in front of the data position Z, and 2 ⁿ⁻¹ (= M Means that there is data. In the case shown in FIG. 5, the FFT data groups F ₂ , F ₃ and F _K-1 are normal, while the FFT data groups F ₁ and F _K are abnormal. However, in FIG. 5, n = 4 (N = 7, M = 8).

If the result of determination in step S15 is that the FFT data group at the data position Z is normal (step S15: Yes), the frequency analysis unit 41 proceeds to step S17 described later.

If the result of determination in step S15 is that the FFT data group at the data position Z is not normal (step S15: No), the frequency analysis unit 41 generates a normal FFT data group by inserting zero data for the shortage ( Step S16). The FFT function group determined to be not normal in step S15 is subjected to a window function before adding zero data. For this reason, discontinuity of data does not occur even if zero data is inserted into the FFT data group. After step S16, the frequency analysis unit 41 proceeds to step S17 described later.

In step S17, the frequency analysis unit 41 obtains a frequency spectrum by performing an FFT operation using the FFT data group (step S17). 6 and 7 are diagrams illustrating examples of frequency spectra calculated by the frequency analysis unit 41. FIG. 6 and 7, the horizontal axis f is the frequency, and the vertical axis I is the intensity. In frequency spectrum curves C ₁ and C ₂ shown in FIGS. 6 and 7, respectively, the lower limit frequency f _LOW and the upper limit frequency f _HIGH of the frequency spectrum are the frequency band of the ultrasonic probe 2 and the pulse signal transmitted by the transmitting / receiving unit 3. For example, f _LOW = 3 MHz and f _HIGH = 10 MHz. Note that the straight line L ₁ shown in FIG. 6 and the straight line L ₂ shown in FIG. 7 will be described in a feature amount extraction process described later. In the first embodiment, the curve and the straight line are composed of a set of discrete points. This also applies to the embodiments described later.

Subsequently, the frequency analysis unit 41 adds a predetermined data step width D to the data position Z to calculate the data position Z of the next FFT data group to be analyzed (step S18). The data step width D here is preferably the same as the data step width used when the B-mode image data generation unit 51 generates the B-mode image data. However, when it is desired to reduce the amount of calculation in the frequency analysis unit 41 In this case, a value larger than the data step width used by the B-mode image data generation unit 51 may be set. FIG. 5 shows a case where D = 15.

Thereafter, the frequency analysis unit 41 determines whether or not the data position Z is greater than the final data position Z _max (step S19). Here, the final data position Z _max may be the data length of the sound ray LD, or may be the data position corresponding to the lower end of the region of interest. As a result of the determination, when the data position Z is larger than the final data position Z _max (step S19: Yes), the frequency analysis unit 41 increments the sound ray number L by 1 (step S20). On the other hand, when the data position Z is equal to or less than the final data position Z _max (step S19: No), the frequency analysis unit 41 returns to step S13. In this way, the frequency analysis unit 41 performs an FFT operation on [{(Z _max −Z ₀ ) / D} +1] (= K) FFT data groups for one sound ray LD. Here, [X] represents the maximum integer not exceeding X.

When the sound ray number L after being incremented in step S20 is larger than the final sound ray number _Lmax (step S21: Yes), the frequency analysis unit 41 returns to the main routine shown in FIG. On the other hand, when the sound ray number L after being incremented in step S20 is equal to or less than the final sound ray number _Lmax (step S21: No), the frequency analysis unit 41 returns to step S12.

In this way, the frequency analysis unit 41 performs K FFT operations for each of (L _max −L ₀ +1) sound rays. The final sound ray number L _max may be given to the last sound ray received by the transmission / reception unit 3, for example, or may be given to the sound ray corresponding to either the left or right boundary of the region of interest. . Hereinafter, let P be the total number of FFT operations (L _max −L ₀ +1) × K performed by the frequency analysis unit 41 for all sound rays.

Following the frequency analysis processing in step S5 described above, the feature amount extraction unit 42 extracts the feature amount by performing regression analysis on the P frequency spectra calculated by the frequency analysis unit 41 (step S7). Specifically, the feature amount extraction unit 42 calculates three feature amounts a, b, and c by calculating a linear expression that approximates the frequency spectrum of the frequency band f _LOW <f <f _HIGH by regression analysis. . A straight line L ₁ shown in FIG. 6 and a straight line L ₂ shown in FIG. 7 are regression lines obtained in step S7.

Thereafter, the tissue property determination unit 43 determines the tissue property in the region of interest of the sample based on the feature amount extracted by the feature amount extraction unit 42 and the known sample information stored in the known sample information storage unit 81 (step S8).

Here, the process (step S8) performed by the tissue property determination unit 43 will be described in detail with reference to the flowchart shown in FIG. First, the tissue characterization determining unit 43 calculates the average and standard deviation of each of the three feature values a, b, and c of the Q (≦ P) sets of FFT data located inside the region of interest (step S31). .

Subsequently, the tissue property determining unit 43 sets a feature amount space used when determining the tissue property (step S32). In the first embodiment, there are two independent parameters among the three characteristic quantities, ie, the inclination a, the intercept b, and the intensity c. Accordingly, it is possible to set a two-dimensional space having two arbitrary feature amounts as components as the feature amount space among the three feature amounts. In addition, a one-dimensional space having any one of the three feature quantities as a component can be set as the feature quantity space. In step S32, the feature amount space to be set is determined in advance, but the operator may select a desired feature amount space by the input unit 6.

FIG. 9 is a diagram illustrating an example of the feature amount space set by the tissue property determination unit 43. In the feature quantity space shown in FIG. 9, the horizontal axis is the feature quantity b, and the vertical axis is the feature quantity c. The point Sp shown in FIG. 9 has, as coordinates of the feature amount space, the average of the feature amounts b and c of the frequency spectrum of the FFT data group included in the region of interest of the specimen calculated by the feature amount extracting unit 42 in step S31. A point (hereinafter, this point is referred to as “specimen average point”) is shown. In addition, areas SA, SB, and SC shown in FIG. 9 indicate groups in which the tissue properties of the known samples stored in the known sample information storage unit 81 are A, B, and C, respectively. In the case illustrated in FIG. 9, the three groups SA, SB, and SC exist in regions that do not intersect with other groups in the feature amount space. As described above, in the first embodiment, since the tissue properties are classified and determined using the characteristic amount of the frequency spectrum obtained by the frequency analysis as an index, different tissue properties can be distinguished from each other.

After step S32, the tissue characterization determining unit 43 uses the average of the specimen average point Sp and the feature quantities b and c of the frequency spectrum of the FFT data group included in each of the groups SA, SB, and SC as coordinates in the feature quantity space. The distances α, β, γ on the feature amount space between the points A ₀ , B ₀ , C ₀ (hereinafter referred to as “known specimen average points”) are calculated (step S33). Here, when the scales of the b-axis component and the c-axis component in the feature amount space are greatly different, it is desirable to appropriately perform weighting for making the contribution of each distance substantially equal.

Subsequently, the tissue property determination unit 43 determines the tissue property of the specimen average point Sp based on the distance calculated in step S33 (step S34). In the case shown in FIG. 9, the distance α is the minimum. Therefore, the tissue property determination unit 43 determines that the tissue property of the specimen is A. When the sample average point Sp is extremely far from the known sample average points A ₀ , B ₀ , C ₀ , the determination result of the tissue property is obtained even if the minimum values of the distances α, β, γ are obtained. Reliability is low. Therefore, when α, β, and γ are greater than a predetermined threshold, the tissue property determination unit 43 may output an error signal. When two or more minimum values occur among α, β, and γ, the tissue property determination unit 43 may select all tissue properties corresponding to the minimum value as candidates, or any one according to a predetermined rule. One tissue property may be selected. In the latter case, for example, a method of setting a high priority for highly malignant tissue properties such as cancer can be mentioned. When two or more minimum values occur among α, β, and γ, the tissue property determination unit 43 may output an error signal.

Thereafter, the tissue property determination unit 43 outputs the distance calculation result in step S33 and the determination result in step S34 (step S35). Thereby, the tissue property determination process in step S8 ends.

After step S8 described above, the determination result display image data generation unit 52 includes the B mode image data generated by the B mode image data generation unit 51, the feature amount calculated by the feature amount extraction unit 42, and the tissue property determination unit 43. The determination result display image data is generated by using the determination result determined by (step S9).

Thereafter, the display unit 7 displays the determination result display image generated by the determination result display image data generation unit 52 (step S10). FIG. 10 is a diagram illustrating a display example of the determination result display image displayed on the display unit 7. The determination result display image 200 shown in the figure is an image display that displays an information display unit 201 that displays various related information including a determination result of tissue properties, and a tissue property emphasized image that emphasizes tissue properties based on a B-mode image. Part 202.

The information display unit 201 includes, for example, specimen identification information (ID number, name, sex, and the like), tissue property determination results calculated by the tissue property determination unit 43, information on feature amounts when performing tissue property determination, gain, and contrast. Ultrasonic image quality information such as is displayed. Here, it is possible to perform display using the average and standard deviation of the feature amounts of the frequency spectrum of the Q sets of FFT data groups located inside the region of interest as the information on the feature amount. Specifically, in the information display unit 201, for example, a = 1.5 ± 0.3 (dB / MHz), b = −60 ± 2 (dB / MHz), c = −50 ± 1.5 (dB / MHz).

The tissue property emphasizing image 300 displayed on the image display unit 202 is equivalent to the B mode image 100 shown in FIG. 3 in which the slices b are equal to R (red), G (green), and B (blue). It is the assigned grayscale image.

When the display unit 7 displays the determination result display image 200 having the above configuration, the operator can more accurately grasp the tissue properties of the region of interest.

Note that the tissue property enhancement image 300 shown in FIG. 10 is merely an example. In addition, for example, by assigning the inclination a, the intercept b, and the intensity c to R (red), G (green), and B (blue), the tissue property enhanced image can be displayed as a color image. In this case, since the tissue characteristic is expressed by a unique color, the operator can grasp the tissue characteristic of the region of interest based on the color distribution of the image. Further, instead of configuring the color space with the RGB color system, the color space may be configured with complementary color system variables such as cyan, magenta, and yellow, and a feature amount may be assigned to each variable. Alternatively, the tissue property enhanced image data may be generated by mixing B-mode image data and color image data at a predetermined ratio. Alternatively, tissue property enhanced image data may be generated by replacing only the region of interest with color image data.

According to the first embodiment of the present invention described above, the frequency spectrum feature quantity in the predetermined region of the specimen is extracted by approximating the frequency spectrum obtained by analyzing the frequency of the received ultrasonic wave. In order to determine the tissue properties of a predetermined region of the specimen by using the quantity and using the characteristic quantity of the frequency spectrum extracted based on the ultrasonic waves reflected by a plurality of known specimens, the strain amount and elastic modulus of the biological tissue It is possible to clearly distinguish the difference between tissues without using. Therefore, it is possible to accurately distinguish the tissue properties and improve the reliability of the measurement results.

FIG. 11 is a diagram illustrating another display example of the determination result display image on the display unit 7. The determination result display image 400 shown in the figure includes an information display unit 401, a first image display unit 402 that displays a B-mode image, and a second image display unit 403 that displays a tissue property emphasized image. In the case illustrated in FIG. 11, the B-mode image 100 is displayed on the first image display unit 402, and the tissue property emphasized image 300 is displayed on the second image display unit 403. Thus, by displaying the B-mode image and the tissue property emphasized image side by side, the difference between the two images can be recognized on one screen. Note that the image displayed on the first image display unit 402 and the image displayed on the second image display unit 403 may be interchanged. Further, the display between the determination result display image 200 and the determination result display image 400 may be switched by an input from the input unit 6.

(Embodiment 2)
The second embodiment of the present invention is different from the first embodiment in the tissue property determination process in the tissue property determination unit. The configuration of the ultrasonic diagnostic apparatus according to the second embodiment is the same as the configuration of the ultrasonic diagnostic apparatus 1 described in the first embodiment. Therefore, in the following description, the same reference numerals are given to the components corresponding to the components of the ultrasonic diagnostic apparatus 1.

The tissue property determination unit 43 uses the feature quantities (a, b, c) of the Q sets of FFT data groups located inside the region of interest as the groups SA, SB, and SC constituting the tissue properties A, B, and C (see FIG. 9), a new population is formed, and then a standard deviation for each feature amount of data constituting each tissue property is obtained.

Thereafter, the tissue property determination unit 43 performs standard deviation of each feature amount of the groups SA, SB, SC in the original population consisting only of known samples, and groups SA, SB in the new population to which new samples are added, respectively. , SC and the standard deviation of each feature quantity (hereinafter, simply referred to as “standard deviation difference”), and the tissue characteristics corresponding to the group including the feature quantity having the smallest standard deviation difference are calculated as the tissue of the specimen. Judged as a property.

Here, the tissue property determination unit 43 may calculate the difference of the standard deviation only with respect to the standard deviation of the feature amount selected in advance from a plurality of feature amounts. In this case, the feature amount may be selected arbitrarily by the operator, or may be automatically performed by the ultrasonic diagnostic apparatus 1.

In addition, the tissue property determination unit 43 calculates a value obtained by appropriately weighting and adding the standard deviation differences of all feature amounts for each group, and the tissue property corresponding to the group having the minimum value is determined as the tissue property of the specimen. May be determined. In this case, for example, when the feature quantity is a, b, c, tissue characterization determining unit 43, three feature amounts a, b, respectively corresponding weights c w _a, w _b, as w _c w _a Calculate (difference of standard deviation of a) + w _b (difference of standard deviation of b) + w _c (difference of standard deviation of c), and determine the tissue properties of the specimen based on the calculated values It will be. Note that the values of the weights w _a , w _b , and w _c may be set arbitrarily by the operator, or may be automatically set by the ultrasonic diagnostic apparatus 1.

Further, the tissue property determination unit 43 calculates a square root of a value obtained by appropriately weighting and adding the square of the difference between the standard deviations of all feature amounts for each group, and the tissue property corresponding to the group having the minimum square root. May be determined as the tissue property of the specimen. In this case, for example, when the feature amounts are a, b, and c, the tissue property determination unit 43 assigns weights corresponding to the three feature amounts a, b, and c to w ′ _a , w ′ _b , and w ′ _{c, respectively.} {W ′ _a · (difference of standard deviation of a) ² + w ′ _b · (difference of standard deviation of b) ² + w ′ _c · (difference of standard deviation of c) ² } ^1/2 The tissue property is determined based on the calculated value. In this case as well, the values of the weights w ′ _a , w ′ _b , and w ′ _c may be arbitrarily set by the operator, or may be automatically set by the ultrasonic diagnostic apparatus 1. May be.

According to the second embodiment of the present invention described above, as in the first embodiment described above, it is possible to accurately distinguish the tissue properties and improve the reliability of the measurement results.

In the second embodiment, the tissue property determination unit 43 determines the tissue property based on a change in standard deviation of each feature amount between the original population and the population to which a new specimen is added. This was just an example. For example, the tissue property determination unit 43 may determine the tissue property based on an average change of each feature amount between the original population and the population to which a new specimen is added.

(Embodiment 3)
The third embodiment of the present invention is different from the first embodiment in the tissue property determination process in the tissue property determination unit. The configuration of the ultrasonic diagnostic apparatus according to the third embodiment is the same as the configuration of the ultrasonic diagnostic apparatus 1 described in the first embodiment. Therefore, in the following description, components corresponding to those of the ultrasonic diagnostic apparatus 1 are denoted by the same reference numerals.

The tissue property determination unit 43 calculates the probability of belonging to each tissue property by using the distance between the average point of the sample in the feature amount space and the average point of the tissue property of the known sample. Specifically, in the case of the feature amount space (b, c) shown in FIG. 9, by using the distances α, β, γ between the sample average point Sp and the known sample average points A ₀ , B ₀ , C ₀ , The probability of belonging to each tissue property is calculated. The probability of belonging to each known specimen is set so that the smaller the distance, the larger the probability. For example, assuming that λ = 100 / (α ^-1 + β ^-1 + γ ^-1 ), the probability belonging to the tissue property A is λ / α, the probability belonging to the tissue property B is λ / β, and the probability belonging to the tissue property C is λ / It can be defined as γ.

In the third embodiment, when the display unit 7 displays the determination result display image, the information display unit displays the probability of belonging to each tissue property. For example, when the display unit 7 displays the determination result display image 200, the information display unit 201 displays the determination result as “probability that the tissue property is A = 60%, probability that the tissue property is B = 5%, tissue property. Is 35% probability ”.

According to the third embodiment of the present invention described above, as in the first embodiment described above, it is possible to accurately distinguish tissue properties and improve the reliability of measurement results.

(Embodiment 4)
The fourth embodiment of the present invention differs from the first embodiment in the tissue property determination process in the tissue property determination unit. The configuration of the ultrasonic diagnostic apparatus according to the fourth embodiment is the same as the configuration of the ultrasonic diagnostic apparatus 1 described in the first embodiment. Therefore, in the following description, the same reference numerals are given to the components corresponding to the components of the ultrasonic diagnostic apparatus 1.

FIG. 12 is a diagram for explaining the outline of the tissue property determination process performed by the tissue property determination unit 43 in the fourth embodiment. In the feature quantity space shown in FIG. 12, the horizontal axis is the feature quantity b, and the vertical axis is the feature quantity c. In this feature amount space, regions are grouped according to organizational properties. The tissue property determination unit 43 determines the tissue property according to the position of the specimen average point. FIG. 12 shows a case where the specimen average point Sp ′ belongs to the group SB ′ (region where the tissue property is B). In this case, the tissue property determination unit 43 determines that the tissue property of the region of interest of the specimen is B.

According to the fourth embodiment of the present invention described above, as in the first embodiment described above, it is possible to accurately distinguish the tissue properties and improve the reliability of the measurement results.

Up to this point, the mode for carrying out the present invention has been described. However, the present invention should not be limited only to the first to fourth embodiments described above. That is, the present invention can include various embodiments without departing from the technical idea described in the claims.

DESCRIPTION OF SYMBOLS 1 Ultrasonic diagnostic apparatus 2 Ultrasonic probe 3 Transmission / reception part 4 Calculation part 5 Image processing part 6 Input part 7 Display part 8 Storage part 9 Control part 21 Signal conversion part 22 Ultrasonic transmission / reception part 41 Frequency analysis part 42 Feature-value extraction Unit 43 tissue property determination unit 51 B mode image data generation unit 52 determination result display image data generation unit 81 known specimen information storage unit 82 window function storage unit 100

B mode image

200, 400 determination

result display image

201, 401 information display unit 202 Image display unit 300 Tissue characteristic emphasized image 402 First image display unit 403 Second image display unit

Claims

An ultrasonic diagnostic apparatus for diagnosing the tissue property of the specimen based on the received ultrasonic wave by transmitting an ultrasonic wave to the specimen to be diagnosed and receiving an ultrasonic wave reflected by the specimen,
A frequency analysis unit that calculates a frequency spectrum by analyzing the frequency of the received ultrasonic wave;
A feature amount extraction unit that extracts a feature amount of the frequency spectrum by approximating the frequency spectrum calculated by the frequency analysis unit;
A storage unit that stores a characteristic amount of a frequency spectrum extracted based on ultrasonic waves respectively reflected by a plurality of known specimens in association with tissue characteristics of the plurality of known specimens;
A tissue property determination unit that determines a tissue property of a predetermined region of the specimen by using the feature amount stored in association with the tissue properties of the plurality of known specimens and the feature amount extracted by the feature quantity extraction unit; ,
An ultrasonic diagnostic apparatus comprising:
The feature amount extraction unit includes:
The ultrasonic diagnostic apparatus according to claim 1, wherein the frequency spectrum is approximated by a polynomial by regression analysis.
The feature amount extraction unit includes:
Approximating the frequency spectrum with a linear equation,
A plurality of feature amounts including the slope of the linear expression, the intercept of the linear expression, the frequency included in the frequency band of the frequency spectrum, and the intensity determined by the slope and the intercept are extracted. Item 3. The ultrasonic diagnostic apparatus according to Item 2.
The storage unit
Storing an average of each feature amount in a group classified for each tissue property with respect to the plurality of known specimens;
The tissue property determination unit
A feature amount space including at least one of the plurality of feature amounts as a component is set, and an average of the feature amounts constituting the component of the feature amount space among the feature amounts of the frequency spectrum in the predetermined region of the specimen is the feature. A specimen average point having coordinates of the quantity space, and a known specimen average point having, as coordinates of the feature quantity space, an average of feature quantities constituting components of the feature quantity space among the feature quantities in the group of the plurality of known specimens The ultrasonic diagnostic apparatus according to claim 3, wherein a tissue property of the specimen is determined based on a distance in the feature amount space.
The tissue property determination unit
5. The ultrasonic wave according to claim 4, wherein a tissue property corresponding to a group that minimizes a distance in the feature amount space between the sample average point and the known sample average point is a tissue property of the sample. Diagnostic device.
The tissue property determination unit
The smaller the distance between the specimen average point and the known specimen average point in the feature amount space, the larger the value, and the probability that the sum of the values corresponding to all the distances is 1 is set for all the distances. The ultrasonic diagnostic apparatus according to claim 4, wherein the tissue characteristics of the specimen are determined probabilistically by calculating each.
The tissue property determination unit
A standard deviation of the feature quantity in the population obtained by adding the feature quantity of the specimen to the group classified for each tissue property in the plurality of known specimens, and a difference between the standard deviation and the standard deviation of the feature quantity in the group The ultrasonic diagnostic apparatus according to any one of claims 1 to 3, wherein a tissue property corresponding to a group having a feature quantity having a minimum is the tissue property of the specimen.
Visual information corresponding to the feature amount of the specimen is generated, and the generated visual information, an image generated based on the received ultrasonic wave, and a result determined by the tissue property determination unit are used. The ultrasonic wave according to any one of claims 1 to 7, further comprising a determination result display image data generation unit that generates determination result display image data for displaying a determination result of tissue characteristics in a predetermined region. Diagnostic device.
The ultrasonic diagnostic apparatus according to claim 8, wherein the visual information is a variable constituting a color space.
An operation method of an ultrasonic diagnostic apparatus for diagnosing the tissue property of the specimen based on the received ultrasonic wave by transmitting ultrasonic waves to the specimen to be diagnosed and receiving ultrasonic waves reflected by the specimen. And
A frequency analysis step of calculating a frequency spectrum by a frequency analysis unit by analyzing the frequency of the received ultrasonic wave,
A feature amount extraction step of extracting a feature amount of the frequency spectrum by approximating the frequency spectrum calculated in the frequency analysis step by a feature amount extraction unit;
Feature quantity read out from a storage unit for storing feature quantities of frequency spectra extracted based on ultrasonic waves respectively reflected by a plurality of known specimens in association with tissue properties of the plurality of known specimens and the feature quantity extracting step A tissue property determination step of determining the tissue property of the predetermined region of the specimen by the tissue property determination unit by using the feature amount extracted in
A method for operating an ultrasonic diagnostic apparatus, comprising:
In the ultrasonic diagnostic apparatus for diagnosing the tissue property of the specimen based on the received ultrasonic wave by transmitting the ultrasonic wave to the specimen to be diagnosed and receiving the ultrasonic wave reflected by the specimen,
A frequency analysis step of calculating a frequency spectrum by a frequency analysis unit by analyzing the frequency of the received ultrasonic wave,
A feature amount extraction step of extracting a feature amount of the frequency spectrum by a feature amount extraction unit by approximating the frequency spectrum calculated in the frequency analysis step;
Feature quantity read out from a storage unit for storing feature quantities of frequency spectra extracted based on ultrasonic waves respectively reflected by a plurality of known specimens in association with tissue properties of the plurality of known specimens and the feature quantity extracting step A tissue property determination step of determining a tissue property of the predetermined region of the specimen by the tissue property determination unit by using the feature amount extracted in
An operation program for an ultrasonic diagnostic apparatus, characterized in that