JP2006280520A - Ultrasonic imaging apparatus, ultrasonic image processing method, and ultrasonic image processing program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultrasonic imaging apparatus capable of extracting a speckle pattern by displaying an ultrasonic image, whose spatial frequency is limited to a relatively high frequency band, as animated image. <P>SOLUTION: The ultrasonic imaging apparatus comprises an ultrasonic probe 100 for transmitting ultrasonic waves according to a plurality of applied driving signals, receiving ultrasonic echo signals generated as the ultrasonic waves are reflected on a subject, and outputting receiving signals, a signal processing part 117 for generating image data expressing ultrasonic image information on the subject by signal-processing the receiving signals output from the ultrasonic probe, an A/D convertor 118, a phase matching part 119, and a band limiting image data generating part 121 for generating band limiting image data expressing the image whose spatial frequency is limited to a band of at least the frequency at the center of the spatial frequency band of the ultrasonic image expressed by the image data generated by the phase matching part 119. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an ultrasonic imaging apparatus that generates an ultrasonic image based on an ultrasonic image signal obtained by transmitting ultrasonic waves and receiving ultrasonic echo signals. Furthermore, the present invention relates to an ultrasonic image processing method and an ultrasonic image processing program for processing image data obtained by such an ultrasonic imaging apparatus.

  In the medical field, various imaging techniques have been developed in order to observe and diagnose the inside of a subject. In particular, ultrasonic imaging that acquires internal information of a subject by transmitting and receiving ultrasonic waves enables real-time image observation, and other medical uses such as X-ray photographs and RI (radio isotope) scintillation cameras. Unlike imaging technology, there is no radiation exposure. Therefore, ultrasonic imaging is used as a highly safe imaging technique in a wide range of areas including gynecological system, circulatory system, digestive system, etc. in addition to fetal diagnosis in the obstetrics field.

  Ultrasound imaging is an image generation technology that uses the property that ultrasound is reflected at the boundary between regions with different acoustic impedances (for example, the boundary between structures), and transmits an ultrasonic beam into a subject such as a human body. Then, an ultrasonic echo signal generated in the subject is received, and a reflection point or reflection intensity at which the ultrasonic echo signal is generated is obtained to obtain a structure (for example, a visceral organ or a diseased tissue) present in the subject. Extract the outline of.

  By the way, in an ultrasonic image obtained by imaging a structurally non-uniform subject such as a living body, a pattern in which bright portions and / or dark portions are scattered appears. Such a pattern is called a speckle pattern, and is generated, for example, by interference of an ultrasonic echo signal reflected by a non-uniform tissue existing inside an internal organ or the like. Since this speckle pattern is a kind of virtual image, the contour of the drawn structure is often unclear.

  In Patent Document 1, the statistical properties of speckle patterns are used to smooth images and extract minute structures, so that the minute structures in a homogeneous tissue structure such as the degree of progression of cirrhosis can be obtained. In an ultrasonic diagnostic apparatus that obtains a tomographic image by irradiating a subject with an ultrasonic pulse in order to observe abnormal abnormal lesions, using the statistical properties of the intensity or amplitude information of echo signals generated from the subject site There is disclosed an ultrasonic diagnostic apparatus including an analysis calculation unit that extracts a specific signal and a display unit that displays a result extracted by the analysis calculation unit.

  Patent Document 2 discloses an ultrasonic wave based on echo data obtained by transmission / reception of ultrasonic waves in order to quantify the fineness of speckles (speckle patterns) included in an ultrasonic image and use it for tissue diagnosis. Image forming means for forming an image, binarization processing means for generating a plurality of binarized images by binarizing the ultrasonic image while changing a threshold level, and each of the binarized images Area coefficient means for obtaining the number of independent areas having high brightness or low brightness by performing a labeling process for each, and a graph creating means for creating a speckle evaluation graph representing the number of independent areas of each threshold level An ultrasonic diagnostic apparatus is disclosed.

Non-Patent Document 1 describes general characteristics and statistical properties of speckle patterns found in ultrasonic tomographic images, and a tissue using the statistical properties of such ultrasonic signals. Research on property diagnosis is introduced.
Japanese Patent Laying-Open No. 2003-61964 (first page, FIG. 1) JP 2004-41617 A (2nd page, FIG. 5) Naohisa Kamiyama, et al., “Tissue Characterization Using Statistical Information of Ultrasound Signals-Toward Tissue Characterization of Liver-”, MEDICAL IMAGING TECHNOLOGY, March 2003, Vol. 21, Vol. 2, p. 112-116

  As described above, in ultrasonic diagnosis, speckles appearing in an ultrasonic image are extracted, analyzed, and displayed in accordance with the purpose of diagnosis. Since speckles are considered to contain information related to tissue properties, if speckles can be extracted and displayed, it can be used for diagnosis of tissue properties. In addition, it is considered that the user desires such a function.

  Here, as described in Non-Patent Document 1, since the speckle pattern is generated by ultrasonic interference, the spatial frequency component of the speckle pattern is considered to be relatively high on the ultrasonic image. For this reason, if an ultrasonic image of a specific relatively high frequency band can be displayed as a moving image, it is easy to extract a speckle pattern, which is considered to lead to diagnosis support of tissue properties. However, at present, no ultrasonic imaging apparatus having such a function has been proposed.

  Therefore, in view of the above points, the present invention provides an ultrasonic imaging apparatus and ultrasonic wave that can extract a speckle pattern by displaying an ultrasonic image limited to a band having a relatively high spatial frequency as a moving image. An object is to provide an image processing method and an ultrasonic image processing program.

  In order to solve the above problems, an ultrasonic imaging apparatus according to the present invention transmits and receives ultrasonic waves toward a subject, and displays an ultrasonic image based on an ultrasonic echo signal obtained thereby. An imaging apparatus, an ultrasonic transmission unit that transmits ultrasonic waves according to a plurality of applied drive signals, and an ultrasonic echo signal generated by reflection of an ultrasonic wave transmitted from the ultrasonic transmission unit on a subject An ultrasonic receiving unit that receives and outputs a received signal, and a signal processing unit that generates image data representing ultrasonic image information about the subject by performing signal processing on the received signal output from the ultrasonic receiving unit And an image limited to a band equal to or higher than the center frequency of the spatial frequency band of the ultrasonic image represented by the image data based on the image data generated by the signal processing means. Generating a band-limited image data representing a; and a band-limited image data generating means.

  An ultrasonic image processing method according to the present invention is an ultrasonic image processing method for displaying an ultrasonic image based on an ultrasonic echo signal obtained by transmitting and receiving an ultrasonic wave toward a subject, Step (a) for generating image data representing ultrasonic image information about the subject by performing signal processing on the received signal obtained by receiving the ultrasonic echo signal, and the step (a). (B) generating band-limited image data representing an image limited to a band equal to or higher than the center frequency of the spatial frequency band of the ultrasonic image represented by the image data based on the image data.

  An ultrasound image processing program according to the present invention is an ultrasound image processing program that displays an ultrasound image based on an ultrasound echo signal obtained by transmitting and receiving ultrasound toward a subject, A procedure (a) for generating image data representing ultrasound image information about the subject by performing signal processing on the received signal obtained by receiving the ultrasound echo signal, and the procedure (a). Based on the image data, the CPU executes a procedure (b) for generating band-limited image data representing an image limited to a band equal to or higher than the center frequency of the spatial frequency band of the ultrasonic image represented by the image data. .

  According to the present invention, an image in which a spatial frequency is limited to a band higher than that of a normal ultrasonic image is generated, so that a speckle pattern having a generally high spatial frequency can be easily displayed. Therefore, when determining the tissue properties of the observation site based on the speckle pattern, it is possible to utilize an ultrasonic imaging apparatus having such a function for effective diagnosis support.

Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings. The same constituent elements are denoted by the same reference numerals, and the description thereof is omitted.
FIG. 1 is a block diagram showing an ultrasonic imaging apparatus according to the first embodiment of the present invention. This ultrasonic imaging apparatus controls an ultrasonic probe 100 that transmits and receives ultrasonic waves, and transmits and receives ultrasonic waves, and generates an ultrasonic image based on an acquired ultrasonic reception signal. And a main body 110.

  The ultrasonic probe 100 includes an ultrasonic transducer array in which a plurality of ultrasonic transducers are arranged. Each ultrasonic transducer is, for example, a piezoelectric ceramic represented by PZT (Pb (lead) zirconate titanate) or a polymer piezoelectric element represented by PVDF (polyvinylidene difluoride). It is manufactured by forming electrodes on both ends of a piezoelectric material (piezoelectric body). When a voltage is applied by sending a pulsed electric signal or a continuous wave electric signal to the electrodes of such an ultrasonic transducer, the piezoelectric body expands and contracts to generate ultrasonic waves. Therefore, a plurality of ultrasonic transducers are electronically controlled to generate pulsed or continuous ultrasonic waves from the respective ultrasonic transducers. Thereby, an ultrasonic beam is formed by synthesizing those ultrasonic waves, and the subject is electronically scanned. The plurality of ultrasonic transducers expand and contract by receiving propagating ultrasonic waves and generate electrical signals. These electric signals are output as ultrasonic reception signals. Such an ultrasonic probe 100 is connected to the ultrasonic imaging apparatus main body via a cable.

  As the ultrasonic probe 100, a linear array probe in which a plurality of ultrasonic transducers are arranged one-dimensionally, a sector probe that can scan the inside of a subject in a fan shape, or a plurality of ultrasonic transducers arranged on a convex surface A convex array probe or the like is used. A two-dimensional array probe in which a plurality of ultrasonic transducers are two-dimensionally arranged may be used. In this case, ultrasonic images relating to a plurality of different cross sections can be obtained without mechanically moving the ultrasonic probe. Alternatively, as the ultrasound probe 100, a body cavity probe that is inserted into a subject and performs ultrasound imaging may be used. Known examples of the body cavity probe include an ultrasonic probe that is used by being inserted into a treatment instrument insertion hole of an endoscope, and an ultrasonic endoscope that is integrated with an endoscope. In such a body cavity probe, ultrasonic imaging is performed by a radial scanning method. In the radial scanning method, an ultrasonic wave is transmitted and received while rotating the probe, and an ultrasonic signal is imaged in synchronization with the rotation, and a plurality of transducers arranged in a circle are electrically connected. There is an electronic radial scanning method in which scanning is performed by controlling automatically. According to such a scanning method, 360 ° around the probe can be displayed at a time. Alternatively, an intracavity probe using a scanning method other than radial scanning is known in which a convex array is arranged at the tip.

  The ultrasonic imaging apparatus main body 110 includes an operation console 111, a control unit 112, a recording unit 113, a scanning control unit 114, a drive signal generation unit 115, a transmission / reception switching unit 116, a signal processing unit 117, and an A / D. A converter 118, a phase matching unit 119, a memory 120, a band-limited image generation unit 121, a DSC (digital scan converter) 122, a D / A converter 123, and a display unit 124 are included. .

  The console 111 is used by the user when inputting various commands and information to the ultrasonic imaging apparatus main body. The console 111 includes an input device such as a keyboard and a touch panel, a pointing device such as a mouse, an adjustment knob, an input button, and the like. In addition, the console 111 is provided with a band limited image selection button 111a operated by the user in order to input a signal used to control the operation in the band limited image generation unit 121.

The control unit 112 includes a CPU and software, and controls each unit of the ultrasonic imaging apparatus.
The recording unit 113 records a basic program for causing the CPU included in the ultrasonic imaging apparatus to execute an operation, a program (software) used for performing various processes, information used for the processes, and the like. Control the recording medium. In addition to the built-in hard disk, an external hard disk, flexible disk, MO, MT, RAM, CD-ROM, or DVD-ROM may be used as the recording medium.

  The scanning control unit 114 is controlled to start and stop operation by the control unit 112, and drives a plurality of ultrasonic transducers included in the ultrasonic probe 100 in accordance with the direction in which the ultrasonic waves are transmitted. The delay time given to the driving signal is set. When a mechanical radial probe is used as the ultrasonic probe 100, the scanning control unit 114 controls the operation of a motor that rotates the probe and transmits the ultrasonic wave in synchronization with the operation. To control.

  The drive signal generation unit 115 includes a plurality of pulsers respectively corresponding to the plurality of ultrasonic transducers included in the ultrasonic probe 100. Each pulser generates a drive signal at a set timing under the control of the scanning control unit 114. Thereby, ultrasonic waves are respectively generated from the plurality of ultrasonic transducers with a predetermined time difference.

  The transmission / reception switching unit 116 inputs the drive signal generated by the drive signal generation unit 115 to the ultrasonic probe 100 and captures a reception signal in the signal processing unit 117 described later in accordance with the control of the control unit 112. Switch at the timing. In this way, by limiting the reading signal reading time zone, an ultrasonic echo signal reflected from a specific depth of the subject is detected.

The signal processing unit 117 includes a plurality of channels respectively corresponding to the plurality of ultrasonic transducers. Each of these channels captures a reception signal output from the corresponding ultrasonic transducer at a predetermined timing, and performs signal processing such as amplification and Nyquist filter processing.
The A / D converter 118 digitally converts the analog signal processed by the signal processing unit 117 to generate detection data.

The phase matching unit 119 performs reception focus processing by giving a delay to a plurality of digitally converted detection data and adding them. As a result, detection data (sound ray data) representing a reception beam focused in a predetermined sound ray direction is generated. Further, by detecting the waveform represented by the sound ray data, image data representing luminance values in a plurality of pixels constituting the ultrasonic image along the sound ray can be obtained.
The memory 120 sequentially stores the image data generated by the phase matching unit 119. When one frame of image data is accumulated in the memory 120, the image data is output to the band limited image generation unit 121.

  The band limited image generation unit 121 generates and outputs band limited image data representing an ultrasonic image whose spatial frequency is limited to a predetermined band based on image data for one frame representing the ultrasonic image. The operation of the band limited image generation unit 121 will be described in detail later.

  The DSC 122 converts the scan format of the band-limited image data output from the band-limited image generation unit 121 to display image data representing image information in the sound ray direction in the scanning space of the ultrasonic beam for display in the physical space. Convert to image data. That is, the DSC 122 performs resampling corresponding to the image display range by performing coordinate conversion and interpolation corresponding to the ultrasonic scanning method. For example, image data obtained by linear scanning is subjected to an interpolation process for generating a linear image. Also, polar coordinate conversion and interpolation processing are performed on image data obtained by sector scanning, convex scanning, or radial scanning.

  An STC (sensitivity time control) for correcting distance attenuation is provided before the DSC 122, and linear gradation processing including gain adjustment and contrast adjustment and γ correction are included after the DSC 122. An image processing unit that performs image processing such as nonlinear gradation processing may be provided.

The D / A converter 123 converts the display image data converted by the DSC 122 into an analog signal and outputs the analog signal.
The display unit 124 is, for example, a raster scan CRT display or LCD display, and displays a moving image or a still image of an ultrasonic image based on the image signal analog-converted by the D / A converter 123.

Next, the operation of the band limited image generation unit 121 shown in FIG. 1 will be described in detail with reference to FIGS. FIG. 2 is a diagram for explaining the operation of the band limited image generation unit 121. FIG. 3 shows the spatial frequency band of the ultrasonic image represented by the image data DT (0) for one frame processed in the band limited image generation unit 121. In FIG. 3, the spatial frequency f ₀ is the center frequency of the spatial frequency band of the ultrasonic image represented by the image data DT (0).

  As shown in FIG. 2, the image data DT (0) for one frame output from the memory 120 is subjected to filter processing such as thinning processing and Nyquist filter processing in a downsampling unit (unsharp image processing unit) 11. Is given. Thereby, down-sampling data LOW (0) having a low spatial frequency component is generated.

Next, the downsampling data LOW (0) is subjected to a process of inserting “0” value data and a filter process such as a smoothing filter process in the upsampling unit 12. Thereby, upsampling data LOW (0) ′ having the same size as the original image data DT (0) is obtained. The frequency band of the upsampling data LOW (0) ′ corresponds to a region of f <f _{0 in} the curve shown in FIG.

Next, the subtraction unit (difference processing unit) 13 performs a process of subtracting the upsampling data LOW (0) ′ from the image data DT (0). Thereby, subband data SUB (1) is obtained. As shown in FIG. 3, the sub-band data SUB (1) is an image data representing an ultrasonic image spatial frequency is limited to f ≧ f _0.

Next, the subband data SUB (1) is subjected to a thinning process and a predetermined filter process in the downsampling unit 14. The down-sampling data SUB_LOW (1) obtained thereby is subjected to processing for inserting “0” value data and predetermined filtering processing in the up-sampling unit 15. Further, the subband data SUB (2) is obtained by subtracting the upsampling data SUB_LOW (1) ′ obtained thereby from the subband data SUB (1) in the subtracting unit 16. As shown in FIG. 3, the subband data SUB (2) is image data representing an ultrasonic image in which the spatial frequency is limited to f ≧ f ₁ . Here, the spatial frequency f ₁ is a center frequency in the band f ≧ f ₀ .

Similarly, the sub-band data SUB (3) is obtained by subjecting the sub-band data SUB (2) to processing in the down-sampling unit 17, the up-sampling unit 18, and the subtracting unit 19. As shown in FIG. 3, the sub-band data SUB (3) is an image data representing an ultrasonic image spatial frequency is limited to f ≧ f _2. Here, the spatial frequency f ₂ is a center frequency in the band f ≧ f ₁ .
Further, the subband data SUB (4), (5),... Are obtained by sequentially performing such processing.

  The selector 20 selects and outputs one of the image data DT (0), the subband data SUB (1), the subband data SUB (2),... According to the band limited image selection signal input from the control unit 112. To do.

The operation of the ultrasonic imaging apparatus according to the present embodiment will be described again with reference to FIG.
When the user starts ultrasonic imaging, the control unit 112 outputs a control signal for starting ultrasonic imaging to each unit. In addition, the user selects a band using the band-limited image selection button of the console 111 in order to display an image whose spatial frequency is limited to a preferred band on the screen. In response to this, a band limited image selection signal is output from the control unit 112 to the band limited image generation unit 121.

  On the other hand, the drive signal generator 115 generates a drive signal for driving each ultrasonic transducer of the ultrasonic probe 100 in accordance with the scan controller 114 operating under the control of the controller 112. Accordingly, an ultrasonic beam is transmitted from the ultrasonic transducer 100, and the subject is scanned by a scanning method such as linear scanning, sector scanning, convex scanning, or radial scanning. The ultrasonic beam thus transmitted toward the subject is reflected by a reflector present in the subject, and a plurality of ultrasonic echo signals generated at that time are reflected by the ultrasonic probe 100. Received by. The received ultrasonic echo signal is converted into an electric signal in each ultrasonic transducer of the ultrasonic probe 100 and input to the ultrasonic imaging apparatus main body as a received signal.

A plurality of received signals input to the ultrasonic imaging apparatus main body are subjected to predetermined signal processing and A / D conversion in the signal processing unit 117, and further subjected to phase matching and detection processing, and thus obtained image data Is temporarily stored in the memory 120. When the image data for one frame is accumulated in the memory 120, the image data is output to the band limited image generation unit 121. In the band limited image generating unit 121, as described above with reference to FIG. 2, the subband data SUB (1), (2),... Representing the band limited image whose spatial frequency is limited to a predetermined band. Is generated. Then, data selected by the user from the sub-band data SUB (1), (2),... And the original image data DT (0) is output to the DSC 122. The data output from the band-limited image generation unit 121 is subjected to scan format conversion processing in the DSC 122, converted into an analog image signal in the D / A converter 123, and supplied to the display unit 124. As a result, a band-limited image whose spatial frequency is limited to a user's favorite band or a moving image or a still image of the original ultrasonic image is displayed on the display unit 124.
Even when the band-limited image or the original ultrasonic image is displayed on the display unit 124, the user switches the command using the band-limited image selection button 111a to display a different band-limited image on the display unit 124. Can be displayed.

  As described above, according to the present embodiment, band-limited image data is generated by downsampling processing and subtraction (difference) processing, so that high-speed processing is possible and band-limited images can be displayed almost in real time. . In addition, by providing a band-limited image selection button on the console, it is possible to display an image whose spatial frequency is limited to a user's favorite band or an original ultrasonic image. Therefore, at the site of medical diagnosis, the user can display a moving image of the band limited image in which the speckle pattern often appears by switching the band of the band limited image, and based on such a band limited image Thus, it is possible to efficiently determine the tissue properties of the observation site in the subject. Thus, the ultrasonic imaging apparatus according to the present embodiment can be effectively used for diagnosis support.

Next, an ultrasonic imaging apparatus according to the second embodiment of the present invention will be described with reference to FIGS. FIG. 4 is a block diagram illustrating a configuration of the ultrasonic imaging apparatus according to the present embodiment.
As shown in FIG. 4, the ultrasonic imaging apparatus according to the present embodiment includes an ultrasonic probe 100 and an ultrasonic imaging apparatus main body 200. The ultrasonic imaging apparatus main body 200 has a console 201 instead of the console 111 of the ultrasonic imaging apparatus main body 110 shown in FIG. 1, a DSC 202 instead of the DSC 122, and a screen composition unit. 203 is further included. Other configurations are the same as those in the ultrasonic imaging apparatus shown in FIG.

  The console 201 further includes a display format selection button 201a in addition to the band limited image selection button 111a for selecting a frequency band. The display format selection button 201a is used when the user inputs a display format of a composite screen described later.

  The DSC 202 stores one frame of image data stored in the memory 120, that is, image data representing a normal ultrasonic image whose spatial frequency is not limited, and band-limited image data output from the band-limited image generation unit 121. By converting the scanning format for both, display image data representing a normal ultrasonic image and display image data representing a band-limited image are generated.

  In accordance with the display format selection signal output from the control unit 112, the screen synthesis unit 203 creates a synthesis screen including two ultrasonic images based on the two types of image data generated in the DSC 202, and generates the synthesized image data. Generate. The display format selection signal is output from the control unit 112 when the user selects a desired display format using the display format selection button 201a.

  As a display format of the composite screen created by the screen composition unit 203, for example, the display formats shown in FIGS. That is, as shown in FIG. 5A, the normal ultrasonic image 901 and the band limited image 902 may be displayed side by side with the same size on the screen 900 of the display unit. Further, as shown in FIG. 5B, the normal ultrasonic image 903 may be enlarged and the band limited image 904 may be reduced and displayed side by side. Such a display format is suitable when it is desired to observe the observation site in detail with the normal ultrasonic image 903 while referring to the presence or absence of the speckle pattern with the band limited image 904. Furthermore, as shown in FIG. 5C, the normal ultrasonic image 905 may be displayed smaller and the band-limited image 906 enlarged and displayed side by side. Such a display format is suitable when the speckle pattern state is desired to be observed in detail from the band limited image 906 while confirming the position and shape of the observation site with reference to the normal ultrasonic image 905.

  As described above, according to the present embodiment, both a normal ultrasonic image whose spatial frequency is not limited and a user's favorite band-limited image are displayed on the screen in a user's favorite display format. Therefore, the efficiency of medical diagnosis can be further improved.

Next, an ultrasonic imaging apparatus according to the third embodiment of the present invention will be described with reference to FIGS. FIG. 6 is a block diagram illustrating a configuration of the ultrasonic imaging apparatus according to the present embodiment.
As shown in FIG. 6, the ultrasonic imaging apparatus according to the present embodiment includes an ultrasonic probe 100 and an ultrasonic imaging apparatus main body 300. The ultrasonic imaging apparatus main body 300 includes a console 301 instead of the console 111 of the ultrasonic imaging apparatus main body 110 illustrated in FIG. 1, and a DSC 303 instead of the DSC 122. In addition, the ultrasonic imaging apparatus main body 300 further includes a band limited image analysis unit 302 and a screen synthesis unit 304 with respect to the ultrasonic imaging apparatus main body 110 illustrated in FIG. 1. Other configurations are the same as those in the ultrasonic imaging apparatus shown in FIG.

  In addition to the band-limited image selection button 111a for selecting a frequency band, the console 301 includes a display format selection button 301a used for the user to input the display format of the composite screen and a band-limited image analysis button 301b. Are further provided. The band limited image analysis button 301b is used when the user inputs a command as to whether or not to analyze the band limited image.

The band limited image analysis unit 302 analyzes the band limited image represented by the band limited image data output from the band limited image generation unit 121.
FIG. 7 is a block diagram showing a configuration of the band limited image analysis unit 302 shown in FIG. As shown in FIG. 7, the band limited image analysis unit 302 includes a switch 31, a first band limited image memory 32, a second band limited image memory 33, and a subtracting unit 34. The switch 31 switches the data output destination from the band-limited image generation unit 121 under the control of the control unit 112, so that the band-limited image data for one frame sequentially output from the band-limited image generation unit 121 The first band limited image memory 32 and the second band limited image memory 33 are alternately stored. When the band limited image data is updated in the first band limited image memory 32 or the second band limited image memory 33, the subtracting unit 34 performs a subtraction process between the band limited image data respectively stored in these memories. To generate frame difference data. This frame difference data represents a time change of the band limited image and is output to the DSC 303 as band limited image analysis data.

  The DSC 303 stores one frame of image data stored in the memory 120, that is, image data representing a normal ultrasonic image, band-limited image data output from the band-limited image generation unit 121, and a band-limited image analysis unit By converting the scanning format for the band limited image analysis data output from 302, display image data representing a normal ultrasonic image, display image data representing a band limited image, and a band limited image Display image data representing the analysis result is generated.

  In accordance with the display format selection signal output from the control unit 112, the screen composition unit 304 creates a composite screen including 1 to 3 images based on the three types of data generated in the DSC 303, and generates composite image data. To do. The display format selection signal is output from the control unit 112 when the user selects a desired display format using the band limited image selection button 301a.

  As a display format of the composite screen created by the screen composite unit 304, only one of a normal ultrasonic image, a band limited image, and an analysis image representing the analysis result is displayed. Alternatively, it may be one (single display) or two of them (dual display). In the latter case, for example, the display formats shown in (a) to (c) of FIG. 5 can be used. Alternatively, all of the normal ultrasonic image, the band limited image, and the analysis image may be displayed (triple display). When performing triple display, for example, as shown in FIG. 8A, a normal ultrasonic image 911, a band limited image 912, and an analysis image 913 are all displayed on the screen 900 in the same size. You may make it do. Further, as shown in FIG. 8B, only one of the three images (for example, the analysis image 914) is displayed in a large size, and the remaining two images (for example, the band limited image 915 and the normal image) are displayed. The ultrasonic image 916) may be displayed in a small size. This display method is suitable when it is desired to observe the analysis image in detail while confirming the position and shape of the observation site with reference to the band limited image and the normal ultrasonic image. Further, as shown in FIG. 8C, two of the three images (band-limited image 917 and analysis image 918) are displayed in a large size, and the remaining one image (eg, normal The ultrasonic image 919) may be displayed in a small size. Use this display when you want to observe in detail the speckle pattern state and its temporal change shown in the band-limited image and analysis image while checking the position and shape of the observation site with reference to the normal ultrasound image. The method is suitable.

  As described above, in the present embodiment, since the characteristics of the band limited image are analyzed by obtaining the time change of the band limited image, it is possible to easily discriminate a part where the time change of the speckle pattern is intense. Become. Accordingly, when the tissue property of the observation site is determined based on the speckle pattern, the determination becomes easy, and the quality and efficiency of the medical diagnosis can be improved. Further, according to the present embodiment, it is possible to select whether or not to analyze the band limited image and to select the pattern of the size of the image displayed on the screen according to the user's preference. Therefore, it can be used effectively for diagnosis support.

Next, an ultrasonic imaging apparatus according to the fourth embodiment of the present invention will be described with reference to FIGS. FIG. 9 is a block diagram illustrating a configuration of the ultrasonic imaging apparatus according to the present embodiment.
As shown in FIG. 9, the ultrasonic imaging apparatus according to the present embodiment includes an ultrasonic probe 100 and an ultrasonic imaging apparatus main body 400. The ultrasonic imaging apparatus main body 400 has a band limited image analysis unit 401 instead of the band limited image analysis unit 302 of the ultrasonic imaging apparatus main body 300 shown in FIG. The present embodiment is characterized by using frequency processing as processing for analyzing a band-limited image. As frequency processing, known frequency conversion processing such as fast Fourier transform (FFT) and wavelet transform is performed. In this embodiment, FFT processing is used. Other configurations are the same as those in the ultrasonic imaging apparatus shown in FIG.

The operation of the band limited image analysis unit 401 will be described below.
FIG. 10 is a diagram for explaining frequency processing performed in the band limited image analysis unit 401, and shows a signal representing a luminance value corresponding to one line in the depth direction in the band limited image. In FIG. 10, the horizontal axis represents time t, which corresponds to the distance in the depth direction of the subject. In FIG. 10, the vertical axis represents the signal intensity.

First, the band-limited image analysis unit 401, for one line of the signal included in the band-limited image data output from the band-limited image generating unit 121, FFT processing on the section of the window width W centered on the time t ₀ I do. As a result, a spatial frequency distribution as shown in FIG. The center frequency or peak frequency f _c of the spatial frequency distribution, as a representative value (feature quantity) at time t.

Such processing is also performed for other sections while shifting the time t _{0 in} the range of W / 2 <t ₀ <T−W / 2. The interval Δt for shifting the time t ₀ is made equal to or larger than the interval between sampling points on one line. Further, regarding the relationship between the interval Δt and the window width W, it is desirable that 0 <Δt <W in order to eliminate the gap in the range to be analyzed. Furthermore, within the range that satisfies the above-mentioned conditions, the window width W, the lower limit value W / 2 of _{t 0,} and the upper limit value of _{t 0 (T-W / 2} ) may be changed. Thereby, as shown in FIG. 11B, an analysis result of the band limited image is obtained. By converting the center frequency f _c in the analysis result to the luminance value, the band-limited image analysis data are obtained. An image represented by performing DSC processing on the band-limited image analysis data represents a change in the depth of the spatial frequency component included in the band-limited image.

  Here, as shown in FIG. 11B, in an ultrasonic image including a band limited image, the spatial frequency generally attenuates as it goes deeper. The reason is that relatively high frequency components in the ultrasonic wave propagating through the subject are easily scattered, and the ultrasonic echo signal from the deep part has a relatively low frequency component, so the resolution decreases as it goes deeper. Because it becomes.

  Therefore, in a band-limited image in which the spatial frequency band is limited to some extent, by further analyzing the spatial frequency, a region having a high spatial frequency like a speckle pattern can be clearly displayed. Is possible. That is, as shown in FIG. 12, in the band-limited image, the spatial frequency attenuates according to the depth, but when a speckle pattern exists in a certain depth region, the brightness is high even if the region is deep. Is displayed.

  As described above, in the present embodiment, an area where specific frequency attenuation is seen is displayed with high luminance, and thus such an area can be easily identified. Therefore, this function is effective for diagnosis support, such as easy determination when performing a medical diagnosis based on a speckle pattern.

  Next, a modification of the ultrasonic imaging apparatus according to the fourth embodiment of the present invention will be described with reference to FIGS. FIG. 13 is a block diagram illustrating a modification of the ultrasonic imaging apparatus according to the present embodiment. The main body 410 of the ultrasonic imaging apparatus further includes a color signal generation unit 411 with respect to the ultrasonic imaging apparatus shown in FIG. Other configurations are the same as those in the ultrasonic imaging apparatus shown in FIG.

In this modification, when performing the band-limited image analysis, the representative value at the time t ₀ shown in FIG. 11 as (features), as shown in (a) of FIG. 14, the center frequency or peak frequency f _c and using the difference between the integrated value SH of the integrated value SL and the center frequency f _c or more ranges of even small range (SL-SH). In this case, as shown in FIG. 14B, an analysis result represented by a positive or negative value is obtained according to the spatial frequency distribution in the section of the window width W (FIG. 10).

Furthermore, band-limited image analysis data is generated based on the difference (SL-SH) in the analysis result. That is, a color signal is assigned to the analysis image in accordance with the sign of the difference (SL−SH), and the absolute value | SL−SH | of the difference value is converted into a luminance value. Specifically, a blue color signal is assigned to an area where (SL-SH)> 0 (an area B shown in FIG. 14B), and an area where (SL-SH) <0 (see FIG. 14). A red color signal is assigned to the area R shown in FIG. The color signal allocation is performed in the color signal generation unit 411 based on the analysis result in the band limited image analysis unit 401.
An image represented by performing DSC processing on the band-limited image analysis data represents a change in the depth of the high-low frequency difference included in the band-limited image.

  Here, as described above, since the spatial frequency is attenuated as it goes deeper in the ultrasonic image, the lower spatial frequency component is usually dominant, and the difference (SL-SH) is positive. . However, in a region having a high spatial frequency component such as a speckle pattern, the difference (SL−SH) is negative because the high spatial frequency component is dominant.

  In this modification, it is possible to easily discriminate such a region by displaying a region where such specific frequency attenuation is seen in different colors (for example, red with respect to blue). Therefore, this function can be effectively utilized for diagnosis support when performing medical diagnosis based on the speckle pattern.

Next, an ultrasonic imaging apparatus according to the fifth embodiment of the present invention will be described with reference to FIGS.
The ultrasonic imaging apparatus according to the present embodiment includes a band limited image analysis unit 501 illustrated in FIG. 15 instead of the band limited image analysis unit 401 of the ultrasonic imaging apparatus main body 400 illustrated in FIG. Other configurations are the same as those in the ultrasonic imaging apparatus shown in FIG.

As illustrated in FIG. 15, the band limited image analysis unit 501 includes a frequency processing unit 51, a switch 52, a first frequency processing memory 53, a second frequency processing memory 54, and a subtraction unit 55.
The frequency processing unit 51 performs a frequency conversion process for each line on the band-limited image data output from the band-limited image generation unit 121, thereby expressing a change in the depth of the spatial frequency component included in the band-limited image. Generate analysis data. The operation of generating the frequency processing and band-limited image analysis data in the frequency processing unit 51 is the same as that described in the fourth embodiment of the present invention.

  The switch 52 switches the data output destination from the frequency processing unit 51 under the control of the control unit 112, thereby analyzing one frame of analysis data sequentially output from the frequency processing unit 51 with the first frequency processing memory 53. They are alternately stored in the second frequency processing memory 54. When the analysis data is updated in the first frequency processing memory 53 or the second frequency processing memory 54, the subtraction unit 55 performs a subtraction process between the analysis data respectively stored in these memories, thereby Generate difference data. This frame difference data is output to the DSC 303 as band limited image analysis data.

  As described above, by obtaining the frame difference of the analysis data obtained by performing the frequency processing on the band limited image, the temporal change of the change according to the depth of the spatial frequency component included in the band limited image is imaged. Is possible. Therefore, such functions can be identified based on the speckle pattern. For example, frequency attenuation specific to the speckle pattern can be seen and a part where the speckle pattern changes with time can be easily identified. This is effective for diagnosis support when making a diagnosis.

As a modified example of the ultrasonic imaging apparatus according to the present embodiment, when the analysis data is generated in the frequency processing unit 51, the difference (in the same way as in the modified example (FIG. 14) of the fourth embodiment of the present invention ( SL-SH) may be used as a representative value at time _{t 0.} In that case, frame difference processing is performed on the difference (SL-SH) obtained by frequency processing, color signals are assigned according to the sign of the value after frame difference processing, and the value after frame difference processing is assigned. Band-limited image analysis data is generated by converting the absolute value into a luminance value.

Next, an ultrasonic imaging apparatus according to the sixth embodiment of the present invention will be described with reference to FIGS.
As shown in FIG. 16, the ultrasonic imaging apparatus according to the present embodiment includes an ultrasonic probe 100 and an ultrasonic imaging apparatus main body 600. The ultrasonic imaging apparatus main body 600 is different from the band limited image generating unit 121 and the band limited image analyzing unit 302 of the ultrasonic imaging apparatus main body 300 illustrated in FIG. 6 in that the band limited image generating unit 601 and the band limited image illustrated in FIG. An analysis unit 602 is included. Other configurations are the same as those in the ultrasonic imaging apparatus shown in FIG.

The band limited image generation unit 601 generates and outputs band limited image data having different frequency bands based on image data for one frame representing an ultrasonic image.
FIG. 17 is a diagram for explaining the operation of the band limited image generation unit 601. FIG. 18 shows the spatial frequency band of the ultrasonic image represented by the image data DT (0) for one frame processed in the band limited image generation unit 601. In FIG. 18, the spatial frequency f ₀ is the center frequency of the spatial frequency band of the ultrasonic image represented by the image data DT (0).

  As shown in FIG. 17, image data DT (0) for one frame output from the memory 120 is subjected to filter processing such as thinning processing and Nyquist filter processing in the downsampling unit 61. Thereby, down-sampling data LOW (0) having a low spatial frequency component is generated.

  Next, the downsampling data LOW (0) is subjected to a process of inserting 0-value data and a filter process such as a smoothing filter process in the upsampling unit 62. Thereby, upsampling data LOW (0) 'having the same size as the original image data DT (0) is obtained. In the subtracting unit 63, subband data SUB (1) is obtained by performing a process of subtracting the upsampling data LOW (0) 'from the original data DT (0).

Next, the subband data SUB (1) is subjected to a thinning process and a predetermined filter process in the downsampling unit 64. The down-sampling data SUB_LOW (0) obtained thereby is up-sampled to the same size as the original image data by performing processing for inserting zero-value data and predetermined filtering processing in the up-sampling unit 65. Is done. Data BAND (1) obtained as a result is output as first band-limited image data (output 1). As shown in FIG. 18, the first band-limited image data BAND (1) is image data representing an ultrasonic image whose spatial frequency is limited to f ₀ ≦ f ≦ f ₁ . Here, the spatial frequency f ₁ is a center frequency in the band f ≧ f ₀ .

Further, the subtracting unit 66 performs a process of subtracting the data BAND (1) from the subband data SUB (1), thereby obtaining the data BAND (2). This data BAND (2) is output as a second band limited image (output 2). As shown in FIG. 18, the second band-limited image data BAND (2) is image data representing an ultrasonic image spatial frequency is limited to f ≦ f _1.
In the present embodiment, a plurality of band limited images whose bands do not overlap each other can be generated by such processing.

Referring to FIG. 16 again, the band-limited image analysis unit 602 includes a band-limited image represented by the two types of band-limited image data BAND (1) and BAND (2) generated by the band-limited image generation unit 601. Analyze.
FIG. 19 is a block diagram illustrating a configuration of the band limited image analysis unit 602. As shown in FIG. 19, the band-limited image analysis unit 602 includes a first frequency processing unit 67, a second frequency processing unit 68, and a subtraction unit 69.

The first frequency processing unit 67 performs frequency conversion processing on the first band limited image data BAND (1) (output 1) output from the band limited image generation unit 601, thereby analyzing the first band limited image. Generate data. On the other hand, the second frequency processing unit 68 performs the frequency conversion process on the second band limited image data BAND (2) (output 2) output from the band limited image generation unit 601 to thereby obtain the second band limited image. Generate analysis data. In the first and second frequency processing units 67 and 62, as described with reference to FIG. 11 in the fourth embodiment, FFT processing is performed on one line of signals included in each band-limited image data. By doing so, a representative value (feature value) at time t ₀ is obtained. The analysis data of the first and second band limited images obtained thereby represents the change in the depth of the spatial frequency component included in each band limited image.

The subtraction unit 69 obtains frequency difference data by performing a subtraction process between the analysis data output from the first and second frequency processing units 67 and 68, respectively. This frequency difference data is output to the DSC 303 as band limited image analysis data.
In this way, by obtaining a difference between analysis data based on two types of band-limited images having different bands, it is possible to image a change in depth of an intensity difference between a low frequency component and a high frequency component included in the band-limited image. It becomes possible.

Next, an ultrasonic imaging apparatus according to the seventh embodiment of the present invention will be described with reference to FIG.
The ultrasonic imaging apparatus according to the present embodiment includes a band limited image analysis unit 701 illustrated in FIG. 20 instead of the band limited image analysis unit 602 of the ultrasonic imaging apparatus main body 600 illustrated in FIG. Other configurations are the same as those in the ultrasonic imaging apparatus shown in FIG.

  As shown in FIG. 20, the band-limited image analysis unit 701 includes a first frequency processing unit 71, a second frequency processing unit 72, a first subtraction unit 73, a switch 74, a first frequency processing memory 75, The second frequency processing memory 76 and the second subtracting unit 74 are included. The configurations and operations of the first frequency processing unit 71, the second frequency processing unit 72, and the subtraction unit 73 are the same as those in the first frequency processing unit 67, the second frequency processing unit 68, and the subtraction unit 69 shown in FIG. And the same for each.

The switch 74 switches the data output destination from the subtracting unit 73 under the control of the control unit 112, so that the frequency difference data for one frame sequentially output from the subtracting unit 73 is transferred to the first frequency processing memory 75 and the first frequency processing memory 75. They are alternately stored in the two-frequency processing memory 76. When the frequency difference data is updated in the first frequency processing memory 75 or the second frequency processing memory 76, the subtraction unit 77 performs a subtraction process between the frequency difference data respectively stored in these memories. Generate frame difference data. This frame difference data is output to the DSC 303 as band limited image analysis data.
Thus, by obtaining the frame difference of the difference between the analysis data based on the two types of band-limited images having different bands, the time change of the depth change of the intensity difference between the low frequency component and the high frequency component included in the band-limited image Can be imaged.

  INDUSTRIAL APPLICABILITY The present invention can be used in an ultrasonic diagnostic apparatus used for medical treatment and nondestructive inspection of structures.

1 is a block diagram illustrating a configuration of an ultrasonic imaging apparatus according to a first embodiment of the present invention. It is a figure for demonstrating operation | movement of the band-limited image generation part shown in FIG. It is a figure showing the spatial frequency band of the ultrasonic image represented by image data DT (0). It is a block diagram which shows the structure of the ultrasonic imaging apparatus which concerns on the 2nd Embodiment of this invention. It is a figure which shows the display format of the synthetic | combination screen produced in the screen synthetic | combination part shown in FIG. It is a block diagram which shows the structure of the ultrasonic imaging device which concerns on the 3rd Embodiment of this invention. It is a block diagram which shows the structure of the band-limited image analysis part shown in FIG. It is a figure which shows the display format of the synthetic | combination screen produced in the screen synthetic | combination part shown in FIG. It is a block diagram which shows the structure of the ultrasonic imaging device which concerns on the 4th Embodiment of this invention. It is a figure for demonstrating the frequency process performed in the band-limited image analysis part shown in FIG. It is a figure for demonstrating the frequency process performed in the band-limited image analysis part shown in FIG. It is a figure for demonstrating the frequency process performed in the band-limited image analysis part shown in FIG. It is a block diagram which shows the modification of the ultrasonic imaging apparatus which concerns on the 4th Embodiment of this invention. It is a figure for demonstrating the frequency process performed in the band-limited image analysis part shown in FIG. It is a block diagram which shows the structure of the zone | band limited image analysis part contained in the ultrasonic imaging device which concerns on the 5th Embodiment of this invention. It is a block diagram which shows the structure of the ultrasonic imaging apparatus which concerns on the 6th Embodiment of this invention. It is a figure for demonstrating operation | movement of the band-limited image generation part shown in FIG. It is a figure for demonstrating the frequency process performed in the band-limited image analysis part shown in FIG. It is a block diagram which shows the structure of the band-limited image analysis part shown in FIG. It is a block diagram which shows the structure of the zone | band limited image analysis part contained in the ultrasonic imaging device which concerns on the 7th Embodiment of this invention.

Explanation of symbols

11, 14, 17, 61, 64 Downsampling unit (non-sharp image processing unit)
12, 15, 18, 62, 65 Upsampling unit 13, 16, 19, 34, 55, 63, 66, 69, 73, 77 Subtraction unit (difference processing unit)
20 Selector 31, 52, 73 Switch 32 First band limited image memory 33 Second band limited image memory 51 Frequency processing unit 53, 67, 75 First frequency memory 54, 68, 75 Second frequency memory 71 First frequency processing unit 72 Second frequency processing unit 100 Ultrasonic probe 110, 200, 300, 400, 410, 600 Ultrasound imaging device main body 111, 201, 301 Console 111a Band-limited image selection button 112 Control unit 113 Recording unit 114 Scanning Control unit 115 Drive signal generation unit 116 Transmission / reception switching unit 117 Signal processing unit 118 A / D converter 119 Phase matching unit 120 Memory 121, 302, 601 Band-limited image generation units 122, 202, 303 Digital scan converter (DSC)
123 D / A converter 124 Display unit 201a, 301a Display format selection button 203, 304 Screen composition unit 301b Band-limited image analysis button 302, 401, 501, 602, 701 Band-limited image analysis unit 411 Color signal generation unit 900, 910 Screens 901, 903, 905, 911, 916, 919 Normal ultrasound images 902, 904, 906, 912, 915, 917 Band-limited images 913, 914, 918 Analysis images

Claims (26)

An ultrasonic imaging apparatus that transmits and receives ultrasonic waves toward a subject and displays an ultrasonic image based on an ultrasonic echo signal obtained thereby,
Ultrasonic transmission means for transmitting ultrasonic waves according to a plurality of applied drive signals;
An ultrasonic receiving means for receiving an ultrasonic echo signal generated by reflection of an ultrasonic wave transmitted from the ultrasonic transmitting means on a subject and outputting a received signal;
Signal processing means for generating image data representing ultrasonic image information about the subject by performing signal processing on the reception signal output from the ultrasonic reception means;
Based on the image data generated by the signal processing means, band limitation for generating band limited image data representing an image limited to a band equal to or higher than the center frequency of the spatial frequency band of the ultrasonic image represented by the image data. Image data generating means;
An ultrasonic imaging apparatus comprising:   The band-limited image data generation means includes means for down-sampling the image data, means for up-sampling the down-sampled image data to the same size as the original image data, and the original image data and the up-sampled image. The ultrasonic imaging apparatus according to claim 1, further comprising means for obtaining a difference from the data.   Band-limited image analysis means for generating analysis data representing a time change of a band-limited image or analysis data representing a depth change of a spatial frequency component based on the band-limited image data generated by the band-limited image data generation means The ultrasonic imaging apparatus according to claim 1, further comprising:   The ultrasonic imaging apparatus according to claim 3, wherein the analysis data representing a time change of the band limited image indicates a time change of a speckle pattern appearing in the band limited image.   5. The ultrasonic imaging apparatus according to claim 3, wherein the band-limited image analysis unit includes a frame difference data generation unit that generates difference data of a plurality of band-limited image data having different frames.   The frame difference data generating means is a switch means for switching the output destination of the band limited image data generated by the band limited image data generating means for each frame, and the band limited image data whose output destination is switched by the switch means. A difference between the first and second storage means for alternately storing the band-limited image data stored in the first storage means and the band-limited image data stored in the second storage means. The ultrasonic imaging apparatus according to claim 5, further comprising a subtracting unit to be obtained.   In the band limited image represented by the band limited image data generated by the band limited image data generating unit, the band limited image analyzing unit performs frequency conversion processing on a plurality of sections divided in the depth direction, The ultrasonic imaging apparatus according to claim 3, further comprising frequency processing means for obtaining a depth change of the spatial frequency component. The frequency processing means performs frequency conversion processing on a plurality of band limited images respectively represented by a plurality of band limited image data of different frames,
Frame difference data generation for obtaining temporal change of spatial frequency component depth change by generating difference data of a plurality of results obtained by performing frequency conversion processing by the frequency processing means by the band limited image analysis means The ultrasonic imaging apparatus according to claim 7, further comprising means.   The frequency processing means obtains a spatial frequency distribution in each section by performing a frequency conversion process on each of the plurality of sections, and uses a center frequency or a peak frequency in the spatial frequency distribution as a representative value of each section. The ultrasonic imaging apparatus according to 7 or 8.   The frequency processing means obtains a spatial frequency distribution in each section by performing a frequency conversion process for each of the plurality of sections, and an integrated value of a spatial frequency component lower than the center frequency or peak frequency of the spatial frequency distribution; The ultrasonic imaging apparatus according to claim 7 or 8, wherein a difference from an integrated value of a spatial frequency component higher than a center frequency or a peak frequency of the spatial frequency distribution is used as a representative value of each section.   The frequency processing means performs a frequency conversion process on a plurality of sections while shifting the center position of the sections at intervals corresponding to the sampling point intervals on the lines in the depth direction included in the band limited image. The ultrasonic imaging apparatus according to claim 9 or 10.   The ultrasonic imaging apparatus according to claim 1, further comprising an input unit used to select a band of the band limited image data generated by the band limited image data generating unit.   The ultrasonic imaging apparatus according to claim 3, further comprising an input unit that is used to select whether or not analysis data is generated in the band-limited image analysis unit. An ultrasonic image represented by the image data generated by the signal processing means, a band limited image represented by the band limited image image data generated by the band limited image data generating means, and the band limited image analyzing means Screen composition means for creating a screen including at least two of the analysis results represented by the analysis data generated by
An input unit used for selecting a pattern of a display size of an ultrasonic image, a band limited image, or an analysis result displayed on a screen created by the screen synthesis unit;
The ultrasonic imaging apparatus according to claim 1, further comprising: An ultrasonic image processing method for displaying an ultrasonic image based on an ultrasonic echo signal obtained by transmitting and receiving an ultrasonic wave toward a subject,
(A) generating image data representing ultrasonic image information related to the subject by performing signal processing on the reception signal obtained by receiving the ultrasonic echo signal;
Based on the image data generated in step (a), generating band-limited image data representing an image limited to a band equal to or higher than the center frequency of the spatial frequency band of the ultrasonic image represented by the image data ( b) and
An ultrasonic image processing method comprising:   Step (b) downsamples the image data generated in step (a), upsamples the downsampled image data to the same size as the original image data, and is further upsampled with the original image data. The ultrasonic image processing method according to claim 15, further comprising obtaining a difference from the obtained image data.   Based on the band limited image data generated in step (b), the method further includes the step (c) of generating analysis data representing a time change of the band limited image or analysis data representing a depth change of the spatial frequency component. The ultrasonic image processing method according to claim 15 or 16.   The ultrasonic image processing method according to claim 17, wherein the analysis data representing a time change of the band limited image indicates a time change of a speckle pattern appearing in the band limited image.   The ultrasonic image processing method according to claim 17 or 18, wherein step (c) includes generating difference data of a plurality of band-limited image data having different frames.   Step (c) performs a frequency conversion process on a plurality of sections divided in the depth direction in the band-limited image represented by the band-limited image data generated in step (b), so that the depth of the spatial frequency component The ultrasonic image processing method according to claim 17, further comprising obtaining a change. An ultrasound image processing program for displaying an ultrasound image based on an ultrasound echo signal obtained by transmitting and receiving ultrasound toward a subject,
(A) generating image data representing ultrasonic image information related to the subject by performing signal processing on the received signal obtained by receiving the ultrasonic echo signal;
A procedure for generating band limited image data representing an image limited to a band equal to or higher than the center frequency of the spatial frequency band of the ultrasonic image represented by the image data based on the image data generated in the procedure (a) ( b) and
Is an ultrasonic image processing program for causing the CPU to execute.   Step (b) down-samples the image data generated in step (a), up-samples the down-sampled image data to the same size as the original image data, and further up-samples the original image data. The ultrasonic image processing program according to claim 21, further comprising obtaining a difference from the obtained image data.   Based on the band limited image data generated in the step (b), the CPU further includes a procedure (c) for generating analysis data representing a time change of the band limited image or analysis data representing a depth change of the spatial frequency component. The ultrasonic image processing program according to claim 21 or 22, wherein the program is executed.   24. The ultrasonic image processing program according to claim 23, wherein the analysis data representing a time change of the band limited image indicates a time change of a speckle pattern appearing in the band limited image.   The ultrasonic image processing program according to claim 23 or 24, wherein the step (c) includes generating difference data of a plurality of band-limited image data having different frames.   In step (c), in the band limited image represented by the band limited image data generated in step (b), the depth of the spatial frequency component is obtained by performing frequency conversion processing on a plurality of sections divided in the depth direction. 24. The ultrasonic image processing program according to claim 23, comprising determining a change.

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