WO2022054288A1 - Ultrasonic observation device, method for operating ultrasonic observation device, and program for operating ultrasonic observation device - Google Patents

Abstract

The ultrasonic observation device pertaining to the present invention comprises: a reception unit for receiving an echo signal of an ultrasonic echo reflected by an observation object; a frequency analysis unit for performing frequency analysis based on the echo signal to calculate a frequency spectrum; a feature value calculation unit for calculating a feature value on the basis of the frequency spectrum calculated by the frequency analysis unit; an image data generating unit for generating image data on the basis of the echo signal; a region setting unit for setting a region with respect to an image based on the image data using the feature value; and an image manipulation unit for manipulating, with respect to the image data, the region set by the region setting unit.

Description

Ultrasound observation device, operation method of ultrasonic observation device and operation program of ultrasonic observation device

The present invention relates to an ultrasonic observation device for observing a tissue to be observed using ultrasonic waves, an operation method of the ultrasonic observation device, and an operation program of the ultrasonic observation device.

Ultrasound may be applied to observe the characteristics of the living tissue or material to be observed. Specifically, ultrasonic waves are transmitted to the observation target, and predetermined signal processing is performed on the ultrasonic echo reflected by the observation target to acquire information on the characteristics of the observation target. The device that has acquired the information generates a B-mode image that expresses the intensity of the reflected wave based on the information. On the other hand, there is also known a technique of generating a feature amount image showing a difference in tissue properties in a living tissue by utilizing the frequency feature amount of ultrasonic waves scattered in the living tissue (see, for example, Patent Document 1). In this technique, visual information corresponding to a frequency feature is superimposed on, for example, a B-mode image to generate a feature image.

Japanese Patent No. 5054254

In general, visual information based on frequency features has a lower spatial resolution than B-mode images. In the feature amount image, the portion of the B-mode image in which the biological tissue is depicted is replaced with visual information. In order to closely examine changes in living tissue with images with high spatial resolution, surgeons such as doctors need to switch to ultrasonic images after confirming the position of the tissue with feature images.

The present invention has been made in view of the above, and is an ultrasonic observation device capable of easily identifying a tissue structure and observing an ultrasonic image thereof, an operation method of the ultrasonic observation device, and an ultrasonic wave. It is an object of the present invention to provide an operation program of an ultrasonic observation device.

In order to solve the above-mentioned problems and achieve the object, the ultrasonic observation apparatus according to the present invention has a receiving unit that receives an echo signal of an ultrasonic echo reflected by an observation target and a frequency analysis based on the echo signal. A frequency analysis unit that calculates the frequency spectrum by performing the above, a feature amount calculation unit that calculates the feature amount based on the frequency spectrum calculated by the frequency analysis unit, and image data that generates image data based on the echo signal. A generation unit, an area setting unit that sets an area for an image based on the image data using the feature amount, and an image processing unit that processes an area set by the area setting unit for the image data. , Equipped with.

Further, in the ultrasonic observation apparatus according to the present invention, in the above invention, the area setting unit calculates the statistical value of the feature amount for each of a plurality of small areas set corresponding to the image based on the image data. , The area is set by comparing the statistical value with a preset threshold value.

Further, in the ultrasonic observation apparatus according to the present invention, in the above invention, the statistical value is a standard deviation of the feature amount calculated at each position included in the small region.

Further, in the ultrasonic observation apparatus according to the present invention, in the above invention, the feature amount calculation unit calculates the feature amount by approximating the frequency spectrum with a non-linear function.

Further, in the ultrasonic observation apparatus according to the present invention, in the above invention, the feature amount calculation unit calculates the feature amount by approximating the frequency spectrum with a linear function.

Further, in the ultrasonic observation apparatus according to the present invention, in the above invention, the image processing unit changes the brightness or contrast of the region in the image based on the image data.

Further, in the ultrasonic observation apparatus according to the present invention, in the above invention, the image processing unit generates a frame image showing the outer edge of the region in the image based on the image data and superimposes it on the image based on the image data. do.

Further, in the above invention, the ultrasonic observation apparatus according to the present invention has an element for receiving the ultrasonic echo and an ultrasonic imaging unit for transmitting the echo signal of the ultrasonic echo to the receiving unit. ..

Further, the ultrasonic observation device according to the present invention has, in the above invention, a display device for displaying an image generated by the image data generation unit or processed image data generated by the image processing unit.

Further, in the operation method of the ultrasonic observation device according to the present invention, the receiving unit receives the echo signal of the ultrasonic echo reflected by the observation target, and the frequency analysis unit performs frequency analysis based on the echo signal. A frequency analysis step for calculating a frequency spectrum, a feature amount calculation step for calculating a feature amount based on the frequency spectrum calculated by the frequency analysis unit, and an image data generation unit for calculating the feature amount. An image data generation step that generates image data based on an echo signal, an area setting step in which an area setting unit sets an area for an image based on the image data using the feature amount, and an image processing unit , The image processing step of processing the area set by the area setting unit with respect to the image data.

Further, in the operation program of the ultrasonic observation device according to the present invention, the echo signal of the ultrasonic echo reflected by the observation target is received by the ultrasonic observation device, and the frequency analysis is performed based on the echo signal to obtain the frequency spectrum. Calculate, calculate the feature amount based on the frequency spectrum, generate image data based on the echo signal, use the feature amount to set a region for the image based on the image data, and set the image. The data is processed to process the set area.

According to the present invention, it is possible to easily identify the tissue structure and observe the ultrasonic image thereof.

FIG. 1 is a block diagram showing a configuration of an ultrasonic observation system including an ultrasonic observation device according to an embodiment of the present invention. FIG. 2 is a flowchart showing an outline of the processing performed by the ultrasonic observation apparatus according to the embodiment of the present invention. FIG. 3 is a diagram for explaining an example in which scatterers of different sizes are present at an observation position of a certain subject. FIG. 4 is a diagram showing an example of a frequency spectrum calculated by the frequency analysis unit of the ultrasonic observation device according to the embodiment of the present invention. FIG. 5 is a diagram showing a straight line having a correction feature amount corrected by the attenuation correction unit of the ultrasonic observation device according to the embodiment of the present invention as a parameter. FIG. 6 is a diagram illustrating a mesh structure including a plurality of small areas for setting an area, which is set corresponding to a display image. FIG. 7 is a diagram for explaining the area setting process performed by the area setting unit. FIG. 8 is a diagram schematically showing an example of a B mode image. FIG. 9 is an example of a display image generated by the image processing unit, and is a diagram illustrating a processed B-mode image (processed image) of the image processing unit. FIG. 10 is a diagram illustrating a display image according to the first modification. FIG. 11 is a diagram illustrating a display image according to the modified example 2. FIG. 12 is a diagram illustrating a display image according to the modified example 3.

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

(Embodiment)
FIG. 1 is a block diagram showing a configuration of an ultrasonic observation system 1 provided with an ultrasonic observation device 3 according to an embodiment of the present invention. The ultrasonic observation system 1 shown in the figure includes an ultrasonic endoscope 2 (ultrasonic probe) that transmits ultrasonic waves to a subject to be observed and receives the ultrasonic waves reflected by the subject, and an ultrasonic probe. It includes an ultrasonic observation device 3 that generates an ultrasonic image based on an ultrasonic signal acquired by the ultrasonic endoscope 2, and a display device 4 that displays an ultrasonic image generated by the ultrasonic observation device 3.

The ultrasonic endoscope 2 converts an electrical pulse signal received from the ultrasonic observation device 3 into an ultrasonic pulse (acoustic pulse) and irradiates the subject at the tip thereof, and is reflected by the subject. It has an ultrasonic vibrator 21 that converts an ultrasonic echo into an electrical echo signal expressed by a voltage change and outputs the ultrasonic echo. The ultrasonic vibrator 21 includes piezoelectric elements arranged one-dimensionally (linearly) or two-dimensionally, and ultrasonic waves are transmitted and received by each piezoelectric element. The ultrasonic transducer 21 corresponds to an ultrasonic imaging unit. The ultrasonic oscillator 21 may be a convex oscillator, a linear oscillator, or a radial oscillator.

The ultrasonic endoscope 2 usually has an imaging optical system and an imaging element, and is inserted into the gastrointestinal tract (esophagus, stomach, duodenum, large intestine) or respiratory organ (tracheal duct, bile duct) of the subject for digestion. It is possible to image tubes, respiratory organs, and surrounding organs (pancreatic duct, gallbladder, bile duct, biliary tract, lymph nodes, mediastinal organs, blood vessels, etc.). Further, the ultrasonic endoscope 2 has a light guide that guides the illumination light to irradiate the subject at the time of imaging. The tip of the light guide reaches the tip of the insertion portion of the ultrasonic endoscope 2 into the subject, while the proximal end is connected to a light source device that generates illumination light. The ultrasonic endoscope 2 is not limited to this, and an ultrasonic probe that does not have an image pickup optical system and an image pickup element may be used.

The ultrasonic observation device 3 includes a transmission / reception unit 31, a signal processing unit 32, a calculation unit 33, an image processing unit 34 that generates various image data, an input unit 35, a control unit 36, and a storage unit 37. To prepare for.

The transmission / reception unit 31 is electrically connected to the ultrasonic endoscope 2, transmits a transmission signal (pulse signal) composed of a high voltage pulse based on a predetermined waveform and transmission timing, and transmits the transmission signal (pulse signal) to the ultrasonic transducer 21, and also super It receives an echo signal, which is an electrical reception signal, from the ultrasonic transducer 21, and generates and outputs digital high frequency (RF: Radio Frequency) signal data (hereinafter referred to as RF data). The transmission / reception unit 31 performs processing such as filtering on the received echo signal, and then performs A / D conversion to generate RF data in the time domain, and outputs the RF data to the signal processing unit 32 and the calculation unit 33. At this time, the transmission / reception unit 31 may perform amplification correction processing according to the reception depth. When the ultrasonic endoscope 2 has a configuration in which an ultrasonic vibrator 21 in which a plurality of elements are provided in an array is electronically scanned, the transmission / reception unit 31 is a multi-beam synthesis unit corresponding to the plurality of elements. It has a channel circuit.

The frequency band of the pulse signal transmitted by the transmission / reception unit 31 may be a wide band that substantially covers the linear response frequency band of the electroacoustic conversion of the pulse signal into the ultrasonic pulse in the ultrasonic transducer 21. This makes it possible to perform an accurate approximation when executing the frequency spectrum approximation processing described later.

The transmission / reception unit 31 transmits various control signals output by the control unit 36 to the ultrasonic endoscope 2, and receives various information including an ID for identification from the ultrasonic endoscope 2 to the control unit 36. It also has a function to send to.

The signal processing unit 32 generates digital B-mode reception data based on the RF data received from the transmission / reception unit 31. The signal processing unit 32 performs known processing such as a bandpass filter, envelope detection, and logarithmic conversion on the RF data to generate digital B-mode reception data. In logarithm conversion, the common logarithm of the amount obtained by dividing the RF data by the reference voltage V _c is taken and expressed in decibel values. The signal processing unit 32 outputs the generated B mode reception data to the image processing unit 34. The signal processing unit 32 uses a general-purpose processor such as a CPU (Central Processing Unit) or a dedicated processor such as various arithmetic circuits that execute specific functions such as FPGA (Field Programmable Gate Array) and ASIC (Application Specific Integrated Circuit). It is composed of.

The calculation unit 33 performs a predetermined calculation on the RF data received from the transmission / reception unit 31. The calculation unit 33 is calculated by the frequency analysis unit 331 and the frequency analysis unit 331, which calculate the frequency spectrum by applying a high-speed Fourier transform (FFT: Fast Fourier Transform) to the RF data generated by the transmission / reception unit 31 and performing frequency analysis. It has a feature amount calculation unit 332 that calculates the feature amount of the frequency spectrum, and a region setting unit 333 that sets a region of an image to be processed based on the feature amount calculated by the feature amount calculation unit 332. The arithmetic unit 33 is configured by using a general-purpose processor such as a CPU and a dedicated processor such as various arithmetic circuits that execute specific functions such as FPGA and ASIC. The details of the processing of the calculation unit 33 will be described later.

The image processing unit 34 has an image data generation unit 341 that generates ultrasonic image data (hereinafter referred to as B mode image data) that converts the amplitude of the echo signal into brightness and displays it, and a region set by the region setting unit 333. It has an image processing unit 342 that generates processed image data obtained by processing an image. The image processing unit 34 is configured by using a general-purpose processor such as a CPU and a dedicated processor such as various arithmetic circuits that execute specific functions such as FPGA and ASIC. The details of the processing of the image processing unit 34 will be described later.

The input unit 35 is realized by using a user interface such as a keyboard, a mouse, and a touch panel, and accepts input of various information.

The control unit 36 controls the entire ultrasonic observation system 1. The control unit 36 is configured by using a general-purpose processor such as a CPU having arithmetic and control functions, and a dedicated processor such as various arithmetic circuits that execute specific functions such as FPGA and ASIC. The control unit 36 collectively controls the ultrasonic observation device 3 by reading information stored and stored by the storage unit 37 from the storage unit 37 and executing various arithmetic processes related to the operation method of the ultrasonic observation device 3. do. It is also possible to configure the control unit 36 by using a CPU or the like common to the signal processing unit 32 and the calculation unit 33.

The storage unit 37 stores various information necessary for the operation of the ultrasonic observation device 3. The storage unit 37 stores a plurality of feature quantities calculated by the attenuation correction unit 332b for each frequency spectrum and image data generated by the image processing unit 34. In addition to the above, the storage unit 37 may be used for, for example, information necessary for amplification processing (relationship between amplification factor and reception depth), information necessary for amplification correction processing (relationship between amplification factor and reception depth), and attenuation correction processing. Stores necessary information, window function information (Hamming, Hanning, Blackman, etc.) required for frequency analysis processing.

Further, the storage unit 37 stores various programs including an operation program for executing the operation method of the ultrasonic observation device 3. The operation program can also be recorded on a computer-readable recording medium such as a hard disk, flash memory, CD-ROM, DVD-ROM, or flexible disk and widely distributed. The various programs described above can also be acquired by downloading via a communication network. The communication network referred to here is realized by, for example, an existing public line network, LAN (Local Area Network), WAN (Wide Area Network), etc., and may be wired or wireless.

The storage unit 37 having the above configuration is realized by using a ROM (Read Only Memory) in which various programs and the like are pre-installed, and a RAM (Random Access Memory) for storing calculation parameters and data of each process. ..

The display device 4 is configured by using a liquid crystal display, an organic EL (Electro Luminescence), a projector, or the like, and displays an image or the like generated by the ultrasonic observation device 3.

FIG. 2 is a flowchart showing an outline of the processing performed by the ultrasonic observation device 3 having the above configuration. First, the ultrasonic observation device 3 receives an echo signal as a measurement result of the observation target by the ultrasonic transducer 21 from the ultrasonic endoscope 2 (step S1).

Subsequently, the image data generation unit 341 generates B-mode image data using the echo signal received by the transmission / reception unit 31 and outputs it to the display device 4 (step S2). Specifically, the image data generation unit 341 performs signal processing using known techniques such as gain processing, contrast processing, and γ correction processing on the B mode received data received from the signal processing unit 32, and also performs signal processing. B-mode image data is generated by thinning out data according to the data step width determined according to the display range of the image on the display device 4. The B-mode image is, for example, a grayscale image.

Further, the image data generation unit 341 has performed coordinate conversion in which the position of the brightness based on the amplitude in the B mode reception data from the signal processing unit 32 is rearranged according to the position in the actual space (scanning range). After that, the gap between the received data for B mode is filled by performing the interpolation processing between the received data for B mode, and the B mode image data is generated. The image data generation unit 341 outputs the generated B-mode image data to the display device 4.

The display device 4 that has received the B-mode image data displays the B-mode image corresponding to the B-mode image data (step S3).
It should be noted that the process may be shifted from step S2 to step S4 without executing the process of step S3.

In step S4, the frequency analysis unit 331 calculates the frequency spectrum for all the sample data groups by performing the frequency analysis by the FFT calculation (step S4). The frequency analysis unit 331 samples the RF data (line data) of each sound line generated by the transmission / reception unit 31 at predetermined time intervals, and generates sample data. The frequency analysis unit 331 calculates the frequency spectrum at a plurality of points (data positions) on the RF data by applying the FFT process to the sample data group. The "frequency spectrum" here means a "frequency distribution of intensity at a certain reception depth z" obtained by subjecting a sample data group to FFT processing. The term "intensity" as used herein means, for example, parameters such as the voltage of the echo signal, the power of the echo signal, the sound pressure of the ultrasonic echo, the acoustic energy of the ultrasonic echo, the amplitude and time integral value of these parameters, and their combinations. Refers to any of.
The result of the FFT calculation is stored in the storage unit 37 together with the reception depth and the reception direction.

In general, when the subject is a living tissue, the frequency spectrum tends to differ depending on the properties of the living tissue scanned by the ultrasonic wave. This is because the frequency spectrum has a correlation with the size, number density, acoustic impedance, etc. of the scatterer that scatters ultrasonic waves. The term "property of living tissue" as used herein means, for example, malignant tumor (cancer), benign tumor, endocrine tumor, mucinous tumor, normal tissue, cyst, vessel and the like.

Here, the frequency spectrum of the subject differs in frequency characteristics (waveform) depending on the structure of the object (size and density of the scattering body existing in the living tissue). FIG. 3 is a diagram for explaining an example in which scatterers of different sizes are present at an observation position of a certain subject. For example, there are scatterers having different sizes and densities depending on the properties of living tissue. In the example of FIG. 3, a scatterer S ₂ having a size different from that of the scatterer S ₁ is present in a part of the set of scatterers S ₁ in a normal tissue. When the scanning region R ₀ is visualized as a B-mode image, it is important to identify the tissue structure in the region R ₁ including the scatterer S ₂ and to observe the ultrasonic image thereof.

Following the frequency analysis process in step S4, the feature amount calculation unit 332 calculates the pre-correction feature amount for each frequency spectrum, and eliminates the influence of ultrasonic wave attenuation on the pre-correction feature amount of each frequency spectrum. The correction feature amount of each frequency spectrum is calculated by performing the attenuation correction (step S5).

The approximation unit 332a calculates the pre-correction feature amount corresponding to each frequency spectrum by performing regression analysis on each of the plurality of frequency spectra generated by the frequency analysis unit 331. The approximation unit 332a calculates the pre-correction feature amount that characterizes this approximated linear expression by performing regression analysis of the frequency spectrum in a predetermined frequency band and approximating the frequency spectrum with a linear expression (regression straight line). For example, in the case of the frequency spectrum C ₁ shown in FIG. 4, the approximation unit 332a performs regression analysis in the frequency band F and approximates the frequency spectrum C ₁ with a linear equation to obtain a regression line L ₁₀ . In other words, the approximation part 332a is a mid-band fit that is a value on the regression line of the slope a ₀ of the regression line L ₁₀ , the intercept b ₀ , and the center frequency f _M = (f _L + f _H ) / 2 of the frequency band F. (Mid-band fit) c ₀ = a ₀ f _M + b ₀ is calculated as the pre-correction feature amount. The "frequency band F" is a frequency band determined by the lower limit frequency f _L and the upper limit frequency f _H.

Of the three pre-correction features, the slope a ₀ correlates with the size of the ultrasonic scatterer, and it is generally considered that the larger the scatterer, the smaller the slope. Further, the section b ₀ has a correlation with the size of the scatterer, the difference in acoustic impedance, the number density (concentration) of the scatterer, and the like. Specifically, it is considered that the section b ₀ has a larger value as the scatterer is larger, has a larger value as the difference in acoustic impedance is larger, and has a larger value as the number density of the scatterer is larger. The midband fit c ₀ is an indirect parameter derived from the slope a ₀ and the intercept b ₀ and gives the intensity of the spectrum at the center within a valid frequency band. Therefore, it is considered that the mid-band fit c ₀ has 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 number density of the scatterer.

Subsequently, the attenuation correction unit 332b calculates the correction feature amount by performing attenuation correction using the attenuation rate for the pre-correction feature amount approximated by the approximation unit 332a for each frequency spectrum, and the calculated correction. The feature amount is stored in the storage unit 37.

In general, the attenuation amount A (f, z) of an ultrasonic wave is the attenuation that occurs while the ultrasonic wave reciprocates between the reception depth 0 and the reception depth z, and the intensity change (difference in decibel expression) before and after the reciprocation. ). It is empirically known that the amount of attenuation A (f, z) is proportional to the frequency in a uniform tissue, and is expressed by the following equation (1).
A (f, z) = 2αzf ... (1)
Here, the proportionality constant α is a quantity called a damping factor. Further, z is the reception depth of ultrasonic waves, and f is the frequency. When the observation target is a living body, the specific value of the attenuation factor α is determined according to the part of the living body. The unit of the attenuation factor α is, for example, dB / cm / MHz. In the present embodiment, it is also possible to configure the configuration in which the value of the attenuation factor α can be changed by input from the input unit 35.

The attenuation correction unit 332b corrects the attenuation of the pre-correction feature quantities (slope a ₀ , intercept b ₀ , midband fit c ₀ ) extracted by the approximation unit 332a according to the following equations (2) to (4). By doing so, the feature quantities a, b, and c are calculated. In the present embodiment, the feature amounts a, b, and c, which are frequency feature amounts, are calculated by the attenuation correction unit 332b.
a = a ₀ + 2αz ・ ・ ・ (2)
b = b ₀ ... (3)
c = c ₀ + A (f _M , z) = c ₀ + 2αzf _M (= af _M + b) ... (4)
As is clear from the equations (2) and (4), the attenuation correction unit 332b makes a correction with a larger correction amount as the ultrasonic wave reception depth z increases. Further, according to the equation (3), the correction regarding the intercept is an identity transformation. This is because the intercept is a frequency component corresponding to frequency 0 (Hz) and is not affected by attenuation.

FIG. 5 is a diagram showing a straight line having the feature quantities a, b, and c calculated by the attenuation correction unit 332b as parameters. The equation for the straight line L ₁ is
I = af + b = (a ₀ + 2αz) f + b ₀ ... (5)
It is represented by. As is clear from this equation (5), the regression line L ₁ has a larger slope (a> a ₀ ) and the same intercept (b = b ₀ ) as compared with the regression line L ₁₀ before attenuation correction. ).

After that, the area setting unit 333 sets the area of the image to be processed based on the feature amount (step S6). FIG. 6 is a diagram illustrating a mesh structure composed of a plurality of small areas for area setting, which are set corresponding to the display image. The outer edge M ₁ of the mesh structure coincides with the outer edge of the B-mode image. Further, the small region m ₁ is formed by partitioning the outer edge M ₁ in a grid pattern. The small area m ₁ is set to a size including a plurality of data positions.
In this embodiment, a mesh structure having a plurality of small regions forming a rectangle will be described as an example, but if a plurality of data positions are included, the small region is not limited to a rectangle and does not have a circle or an ellipse. You may. At this time, the small area may partially overlap with the adjacent small area.

The area setting unit 333 calculates the standard deviation of the feature amount of each data position included in the small area m ₁ for each small area m 1. Then, the area setting unit 333 compares the standard deviation with the preset threshold value for all the small areas m ₁ and determines whether or not to set the small area m ₁ to be processed by the image. do. Here, the threshold value is a value set corresponding to the standard deviation, and is set based on the standard deviation corresponding to the notable tissue property. The area setting unit 333 determines whether or not the small area m ₁ to be determined is the image processing target based on the magnitude relationship set according to the organizational properties. For example, when determining a type having a small standard deviation in normal tissue properties, the region setting unit 333 determines that if the standard deviation is larger than the threshold value, it is set in the small region m ₁ to be processed in the image. Here, the threshold value is stored in the storage unit 37 in association with the tissue structure.

FIG. 7 is a diagram for explaining the area setting process performed by the area setting unit. For example, when the area setting unit 333 scans the structure shown in FIG. 3, the small area m ₁ (small area m ₁₀ in FIG. 7) overlapping the area R ₁ is obtained from the standard deviation of each small area m ₁ . Set as a machining area. In FIG. 7, hatching is attached to a small area set as a machining area. In FIG. 7, the reference numeral m ₁₀ is attached to the target small area. For example, when the tissue structure shown in FIG. 3 is ultrasonically scanned, a processed region is formed by a small region (small region m ₁₀ ) overlapping the region R ₁ .

The image processing unit 342 processes the image at the position corresponding to the processing area set in step S6 in the B mode image generated in step S2 (step S7). In this embodiment, the brightness or contrast of the image is changed. The image processing unit 342 increases the brightness or contrast of the image in the processing area.

After that, the image processing unit 342 replaces the processed image processed in step S7 with the corresponding position of the B mode image data generated by the image data generation unit 341, or superimposes the processed image on the processed image data. Generate (step S9).

After that, in the display device 4, under the control of the control unit 36, the processed image corresponding to the processed image data generated by the image processing unit 342 is displayed. FIG. 8 is a diagram schematically showing an example of a B mode image. FIG. 9 is an example of a display image generated by the image processing unit, and is a diagram illustrating a processed B-mode image (processed image) of the image processing unit. In the B-mode image _WB2 (see FIG. 9) processed by the image processing unit 342, the standard deviation of the feature amount is large compared to the B-mode image _WB1 (see FIG. 8) before processing, and the texture is notable. The image of the possible region R ₁₀ is highlighted.

In the embodiment of the present invention described above, the processed area of the B mode image is set based on the feature amount, and the processed image data is generated by performing the processing of emphasizing the image in the processed area. The processed image data is a B-mode image having a higher spatial resolution than an image based on visual information calculated from the feature amount, and in the B-mode image, the image of the processed area set based on the feature amount is emphasized. Therefore, it becomes easy to visually recognize the region of interest in the B-mode image. As a result, according to the present embodiment, it is possible to easily identify the tissue structure and observe the ultrasonic image thereof. As a result, the region where the tissue structure is changed can be easily examined by the B mode image.

Further, according to the present embodiment, since the processing area of the B mode image is set based on the frequency feature amount more sensitive to the change of the tissue structure than the B mode image and the variation thereof, the area where the tissue structure is disturbed is set. It is possible to find out with high accuracy and set the area of the B mode image to be processed with high accuracy. In the above-described embodiment, an example of calculating the standard deviation as the variation of the feature amount has been described, but other parameters such as variance may be calculated as the variation value.

(Modification 1)
Next, a modification 1 of the embodiment will be described with reference to FIG. FIG. 10 is a diagram illustrating a display image according to the first modification. Since the configuration of the ultrasonic observation system according to the present modification 1 is the same as that of the ultrasonic observation system 1 described above, the description thereof will be omitted. Hereinafter, processing different from the embodiment will be described.

In the present modification 1, the image processing unit 342 generates a frame image G ₁ indicating the outer edge of the processing area set by the area setting unit 333, and superimposes this frame image G ₁ on the B mode image to process the processed image. Generate data. In the processed image W _B3 shown in FIG. 10, the frame image G ₁ is superimposed on the position corresponding to the processed area set by the area setting unit 333 in the B mode image. A B mode image is displayed in the internal area of the frame image G ₁ . Further, the frame image G ₁ may be set to a color different from that of the B mode image. Further, in the frame image G ₁ , the type of the line indicating the frame can be set to a solid line, a broken line, a alternate long and short dash line, or the like.

In the modification 1 described above, the processing area of the B mode image is set based on the feature amount, and the frame image showing the outer frame of the processing area is superimposed on the B mode image to generate the processed image data. The processed image data is a B-mode image having a higher spatial resolution than an image based on visual information calculated from the feature amount, and the range of the processed area set based on the feature amount is shown in the B-mode image. Therefore, it becomes easy to visually recognize the region of interest in the B-mode image. As a result, according to the present modification 1, it is possible to easily identify the tissue structure and observe the ultrasonic image thereof.

(Modification 2)
Next, a modification 2 of the embodiment will be described with reference to FIG. FIG. 11 is a diagram illustrating a display image according to the modified example 2. Since the configuration of the ultrasonic observation system according to the second modification is the same as that of the ultrasonic observation system 1 described above, the description thereof will be omitted. Hereinafter, processing different from the embodiment will be described.

In the second modification, the image processing unit 342 generates a processed image G ₂ showing a color different from the B mode image of the color of the processed area set by the area setting unit 333, and the processed image G ₂ is set to the B mode. Processed image data is generated by superimposing it on the image. In the processed image W _B4 shown in FIG. 11, the processed image G ₂ is superimposed on the position corresponding to the processed area set by the area setting unit 333 in the B mode image. When the B-mode image is displayed in gray scale, the processed image G ₂ is displayed in a color that can be distinguished from the B-mode image, such as red or blue. Further, the processed image G ₂ has transparency. Therefore, the B mode image at the position overlapping with the processed image G ₂ is displayed in such a manner that the color of the processed image G ₂ is given.

In the modification 2 described above, the processing area of the B mode image is set based on the feature amount, and the processed image in which the processing area is colored is superimposed on the B mode image to generate the processed image data. The processed image data is a B-mode image having a higher spatial resolution than an image based on visual information calculated from the feature amount, and in the B-mode image, the range of the processed area set based on the feature amount is set. Since it is shown by a color different from that of the B mode image, it becomes easy to visually recognize the region of interest in the B mode image. As a result, according to the present modification 2, it is possible to easily identify the tissue structure and observe the ultrasonic image thereof.

(Modification 3)
Next, a modification 3 of the embodiment will be described with reference to FIG. FIG. 12 is a diagram illustrating a display image according to the modified example 3. Since the configuration of the ultrasonic observation system according to the third modification is the same as that of the ultrasonic observation system 1 described above, the description thereof will be omitted. Hereinafter, processing different from the embodiment will be described.

In the present modification 3, the image processing unit 342 performs filter processing in the processing area set by the area setting unit 333. The image processing unit 342 performs a filter process using a spatial filter on the B mode image in the processing region to generate processed image data. Examples of the filter used by the image processing unit 342 for the filter processing include an averaging filter and a filter using a coefficient. The image processing unit 342 sets the coefficient of the spatial filter to, for example, a coefficient according to the characteristics of the tissue structure to be identified, and performs the filter processing. The processed image _WB5 shown in FIG. 12 is an image in which the amount of information in the area R ₁₀ corresponding to the processed area set by the area setting unit 333 in the B mode image is reduced by the filtering process. In region R ₁₀ , for example, components corresponding to the characteristics of the tissue structure are extracted, and only the extracted components are displayed.

In the modification 3 described above, the processing area of the B mode image is set based on the feature amount, and the B mode image of the processing area is filtered to generate the processed image data. The processed image data is a B-mode image having a higher spatial resolution than an image based on visual information calculated from the feature amount, and in the B-mode image, the range of the processed area set based on the feature amount is set. Since only the components extracted by the filtering process are displayed, it becomes easy to visually recognize the region of interest in the B-mode image. As a result, according to the present modification 3, it is possible to easily identify the tissue structure and observe the ultrasonic image thereof, that is, the image of the tissue structure that is particularly noteworthy.

In the embodiments and the modifications 1 to 3, the processing contents of the image processing unit 342 can be appropriately combined.

Although the embodiments for carrying out the present invention have been described so far, the present invention should not be limited only to the above-described embodiments. The present invention may include various embodiments not described here. In the above-described embodiment, an extracorporeal ultrasonic probe that irradiates ultrasonic waves from the body surface of the subject may be applied as the ultrasonic probe. Extracorporeal ultrasonic probes are commonly used to observe abdominal organs (liver, gallbladder, bladder), breasts (particularly mammary glands), and thyroid glands.

In the above-described embodiment, the feature amount calculation unit 332 has described an example in which regression analysis is performed to approximate the frequency spectrum with a linear function to obtain a regression line, but the second-order or higher is obtained by regression analysis. The frequency spectrum may be approximated by a polynomial (non-linear function) of.

The ultrasonic observation device, the operation method of the ultrasonic observation device, and the operation program of the ultrasonic observation device according to the present invention described above are useful for easily identifying the tissue structure and observing the ultrasonic image. Is.

1 Ultrasonic observation system 2 Ultrasonic endoscope 3 Ultrasonic observation device 4 Display device 21 Ultrasonic oscillator 31 Transmission / reception unit 32 Signal processing unit 33 Calculation unit 34 Image processing unit 35 Input unit 36 Control unit 37 Storage unit 331 Frequency analysis Part 332 Feature amount calculation part 332a Approximate part 332b Damping correction part 333 Area setting part 341 Image data generation part 342 Image processing part

Claims (11)

1. A receiver that receives the echo signal of the ultrasonic echo reflected by the observation target,
   A frequency analysis unit that calculates a frequency spectrum by performing frequency analysis based on the echo signal,
   A feature amount calculation unit that calculates a feature amount based on the frequency spectrum calculated by the frequency analysis unit, and a feature amount calculation unit.
   An image data generation unit that generates image data based on the echo signal,
   An area setting unit that sets an area for an image based on the image data using the feature amount, and a region setting unit.
   An image processing unit that processes an area set by the area setting unit with respect to the image data, and an image processing unit.
   An ultrasonic observation device equipped with.
2. The area setting unit is
   The statistical value of the feature amount is calculated for each of a plurality of small areas set corresponding to the image based on the image data.
   The area is set by comparing the statistical value with a preset threshold value.
   The ultrasonic observation device according to claim 1.
3. The statistical value is the standard deviation of the feature amount calculated at each position included in the small area.
   The ultrasonic observation device according to claim 2.
4. The feature amount calculation unit calculates the feature amount by approximating the frequency spectrum with a nonlinear function.
   The ultrasonic observation device according to claim 1.
5. The feature amount calculation unit calculates the feature amount by approximating the frequency spectrum with a linear function.
   The ultrasonic observation device according to claim 1.
6. The image processing unit is
   Changing the brightness or contrast of the area in an image based on the image data.
   The ultrasonic observation device according to claim 1.
7. The image processing unit is
   A frame image showing the outer edge of the region in the image based on the image data is generated.
   Overlaid on an image based on the image data,
   The ultrasonic observation device according to claim 1.
8. An ultrasonic imaging unit that has an element that receives the ultrasonic echo and transmits the echo signal of the ultrasonic echo to the receiving unit.
   The ultrasonic observation device according to claim 1.
9. A display device that displays an image generated by the image data generation unit or processed image data generated by the image processing unit.
   The ultrasonic observation device according to claim 1.
10. The receiving step in which the receiving unit receives the echo signal of the ultrasonic echo reflected by the observation target,
    A frequency analysis step in which the frequency analysis unit performs frequency analysis based on the echo signal to calculate a frequency spectrum, and
    The feature amount calculation unit calculates the feature amount based on the frequency spectrum calculated by the frequency analysis unit, and the feature amount calculation step.
    An image data generation step in which the image data generation unit generates image data based on the echo signal, and
    An area setting step in which the area setting unit sets an area for an image based on the image data using the feature amount, and
    An image processing step in which the image processing unit processes an area set by the area setting unit with respect to the image data, and an image processing step.
    How to operate an ultrasonic observation device including.
11. For ultrasonic observation equipment,
    Receives the echo signal of the ultrasonic echo reflected by the observation target,
    A frequency analysis based on the echo signal is performed to calculate a frequency spectrum, and the frequency spectrum is calculated.
    The feature amount is calculated based on the frequency spectrum, and the feature amount is calculated.
    Image data is generated based on the echo signal,
    Using the feature amount, a region is set for the image based on the image data, and the area is set.
    The set area is processed for the image data.
    An operation program for an ultrasonic observation device that makes things happen.

Images