Ultrasound diagnostic device and program

Abstract

To suppress the scattered acoustic noise due to a high-frequency ultrasonic signal that is susceptible to scattering while drawing an echo component of a tissue (reflector) based on reflection of an ultrasonic wave with the high resolution even in a subject having many scatterers in the tissue, and achieve both of the high resolution and the tissue recognition performance.SOLUTION: An ultrasonic diagnostic device 100A comprises: a sound ray signal generation unit 14A which generates a sound ray signal on the basis of a reception signal obtained from an ultrasonic probe 2 that transmits / receives an ultrasonic wave to / from a subject; imaging signal extraction units 15a1 to 15an which generate a plurality of imaging signals by performing filtering passing through a plurality of different bands from the sound ray signal; and an imaging signal calculation unit 15b which mutually calculates the plurality of imaging signals.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an ultrasound diagnostic apparatus and a program. [Background technology]

[0002] Ultrasound diagnosis is a simple procedure in which an ultrasound probe is placed on the surface of a patient's body or inside a body cavity to obtain ultrasound images of the heart or fetus, and is highly safe and can be performed repeatedly. Ultrasound diagnostic devices used for such ultrasound diagnosis are known.

[0003] Ultrasound images are usually displayed without distinguishing between echo signal components of reflected ultrasound (echoes) obtained by reflection from structures larger than the ultrasonic wavelength and echo signal components obtained by scattering from structures smaller than the ultrasonic wavelength. Reflector echo signals from reflectors larger than the ultrasonic wavelength are signals that correspond to the shape and structure of the reflector, and are obtained directly as that shape. In contrast, scatterer echo signals from scatterers smaller than the ultrasonic wavelength do not directly reflect that shape, because they are smaller than the ultrasonic wavelength.

[0004] However, the scatterer echo signal is the result of scattering and interference originating from tissue, and in parenchymal parts such as the liver and thyroid gland, it is observed as so-called speckle, and its uniformity and granularity are used as one of the diagnostic information.

[0005] In addition, it is known that the skeletal muscles of young people are usually composed mainly of muscle tissue, and there is little acoustic scattering within the muscles, but in elderly people, fatty tissue enters the skeletal muscles, which causes acoustic scattering and increases muscle brightness (see non-patent document 1).

[0006] Furthermore, a technique for obtaining a desired ultrasound image by adding together multiple ultrasound images is known. For example, an image processing device is known that calculates a weighting coefficient according to pixel value change information, which indicates a larger absolute value as the spatial change increases, from sampling data obtained by an ultrasound diagnostic device, and adds the sampling data and a smoothed image of the sampling data using the weighting coefficient (see Patent Document 1). This image processing device reliably removes or reduces image noise, mainly consisting of high-frequency components, while reliably preserving information on important areas for observation that contain many high-frequency components, such as the boundaries of structures, on the image, and also reduces speckle noise.

[0007] Also known is an ultrasonic diagnostic device that extracts multiple frequency components from a received signal obtained by receiving ultrasonic waves, generates multiple types of image data based on the intensity changes of the multiple frequency components, and synthesizes at least one type of image data by performing spatial filtering (see Patent Document 2). The synthesized image data of this ultrasonic diagnostic device highlights tissues by utilizing differences in the frequency pass characteristics of biological tissues.

[0008] Also, an ultrasonic imaging device is known that raises a received echo signal having a center frequency of nf1 (n: natural number) to the (n+1)th power, raises a received echo signal having a center frequency of (n+1)f1 to the nth power, and obtains signals both having a center frequency of n(n+1)f1, and performs phase-sensitive detection of both the obtained signals to obtain signed echo signals corresponding to interfaces where acoustic impedance increases and interfaces where acoustic impedance decreases (see Patent Document 3). [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-51229 [Patent Document 2] Japanese Patent Application Laid-Open No. 2006-204594 [Patent Document 3] Japanese Patent Application Laid-Open No. 2009-39284 [Non-patent literature]

[0010] [Non-Patent Document 1] Relationship between quadriceps echo intensity and functional and morphological characteristics in older men and women (Archives of Gerontology and Geriatrics,2017-01-24 electronic version) Summary of the Invention [Problem to be solved by the invention]

[0011] There is a demand for suppressing noise (scattered acoustic noise), such as speckles due to scattered components in ultrasound images of a subject. In particular, as described in Non-Patent Document 1, tissue changes cause ultrasound image visualization to be more degraded in elderly people than in younger people due to scattered components, making it difficult to see the target tissue or the puncture needle during puncture procedures in various parts of skeletal muscle or the neck, making it difficult to perform the procedure safely and accurately.

[0012] However, while the image processing device in Patent Document 1 can maintain edge resolution for structures with high signal intensity, such as the edges of organs, tissue structures with small differences in signal intensity, such as microstructures within organs or tumors, are smoothed in the same way as speckles, resulting in a loss of resolution.

[0013] Furthermore, although the ultrasound diagnostic device of Patent Document 2 can obtain information based on differences in frequency characteristics of tissues, it is not possible to obtain high resolution because the image is necessarily constructed from narrowband signals centered on a selected frequency.

[0014] Furthermore, even if the same received signal (received echo signal) is raised to the nth power as in the ultrasonic imaging device described in Patent Document 3, scattered acoustic noise cannot be removed.

[0015] The objective of the present invention is to achieve both high resolution and tissue recognition by suppressing scattered acoustic noise caused by high-frequency ultrasound signals that are easily affected by scattering, while still being able to visualize the echo components of tissue (reflectors) based on ultrasound reflection with high resolution even in subjects with many scatterers in the tissue. [Means for solving the problem]

[0016] In order to solve the above problem, the ultrasonic diagnostic apparatus of the invention described in claim 1 comprises: Obtained from an ultrasound probe that transmits and receives ultrasound to the subject Corresponding to one frame a sound ray signal generating unit that generates a sound ray signal based on the received signal; an imaging signal generating unit that generates a plurality of imaging signals by filtering the sound ray signals through a plurality of different bands; The plurality of imaging signals By multiplication and a calculation unit that performs mutual calculations.

[0017] The ultrasonic diagnostic device of the invention described in claim 2 comprises: Obtained from an ultrasound probe that transmits and receives ultrasound to the subject Corresponding to one frame a sound ray signal generating unit that performs delay-and-sum on a received signal under a plurality of different delay-and-sum conditions to generate a plurality of sound ray signals; and a calculation unit that performs mutual calculations on a plurality of imaging signals based on the plurality of sound ray signals.

[0018] The invention described in claim 3 is the ultrasonic diagnostic apparatus described in claim 2, The imaging signal generating unit generates a plurality of imaging signals by filtering the plurality of sound ray signals so that the signals pass through a plurality of different bands.

[0019] The invention described in claim 4 is 2 or 3 In the ultrasonic diagnostic apparatus described in The calculation unit multiplies the plurality of imaging signals as the mutual calculation.

[0020] The invention described in claim 5 is the ultrasound diagnostic apparatus according to any one of claims 1 to 4, The calculation unit performs a power root calculation process on the mutually calculated imaging signals according to the plurality of imaging signals.

[0021] The invention described in claim 6 is the ultrasound diagnostic apparatus according to any one of claims 1 to 5, The calculation unit performs LUT conversion processing on the mutually calculated imaging signal.

[0022] The invention described in claim 7 is the ultrasound diagnostic apparatus according to any one of claims 1 to 6, The ultrasonic probe has a -20 dB frequency band ratio of 100% or more.

[0023] The invention described in claim 8 is the ultrasound diagnostic apparatus according to any one of claims 1 to 7, a transmitting unit that generates a drive signal including a plurality of fundamental waves with different frequencies and outputs the drive signal to the ultrasonic probe; The sound ray signal generating unit generates sound ray signals having harmonic components of the plurality of fundamental waves.

[0024] The invention described in claim 9 is the ultrasound diagnostic apparatus according to any one of claims 1 to 8, The calculation unit sets luminance values of the imaging signal before the mutual calculation to 0 if the luminance value is equal to or less than a certain value.

[0025] The invention described in claim 10 is the ultrasonic diagnostic apparatus according to any one of claims 1 to 9, The system includes a first display control unit that simultaneously and in parallel displays on a display unit a normal image based on a normal imaging signal that has not undergone the mutual operation and a mutual operation image based on the imaging signal that has undergone the mutual operation.

[0026] The invention described in claim 11 is the ultrasonic diagnostic apparatus according to any one of claims 1 to 10, an analysis unit that generates a difference image between a normal image based on the normal imaging signal that has not been subjected to the mutual operation and a mutual operation image based on the imaging signal that has been subjected to the mutual operation; and a second display control unit that displays the difference image on a display unit.

[0027] The invention described in claim 12 is the ultrasonic diagnostic apparatus described in claim 11, The second display control unit applies color to the difference image and displays the colored difference image on the display unit.

[0028] The invention described in claim 13 is the ultrasonic diagnostic apparatus described in claim 11 or 12, the analysis unit calculates an index value based on the difference image; The second display control unit displays an index value based on the difference image on the display unit.

[0029] The invention described in claim 14 is the ultrasound diagnostic apparatus according to any one of claims 1 to 13, The imaging signal is image data.

[0030] The program of the invention described in claim 15 is Computer, Obtained from an ultrasound probe that transmits and receives ultrasound to the subject Corresponding to one frame a sound ray signal generating unit that generates a sound ray signal based on the received signal; an imaging signal generating unit that generates a plurality of imaging signals by filtering the sound ray signals through a plurality of different bands; The plurality of imaging signals By multiplication a computing unit that performs mutual computation; Function as.

[0031] The program of the invention described in claim 16 is Computer, Obtained from an ultrasound probe that transmits and receives ultrasound to the subject Corresponding to one frame a sound ray signal generating unit that performs delay-and-sum on the received signal under a plurality of different delay-and-sum conditions to generate a plurality of sound ray signals; a calculation unit that performs mutual calculation on a plurality of imaging signals based on the plurality of sound ray signals; Function as. [Effects of the Invention]

[0032] According to the present invention, even in a subject with many scatterers in the tissue, the tissue (reflectors) can be visualized with high resolution while suppressing scattered acoustic noise, thereby achieving both high resolution and tissue recognition. [Brief explanation of the drawings]

[0033] [Figure 1] 1 is a diagram showing the external configuration of an ultrasound diagnostic apparatus according to a first embodiment of the present invention. [Figure 2] 1 is a block diagram showing the functional configuration of an ultrasound diagnostic apparatus according to a first embodiment. [Figure 3] FIG. 2 is a block diagram showing the functional configuration of a transmission unit. [Figure 4] 1A is a diagram showing frequency characteristics of the signal strength of a transmitted ultrasonic wave, and FIG. 1B is a diagram showing frequency characteristics of the signal strength of a reflected ultrasonic wave. [Figure 5] FIG. 10 is a diagram showing frequency characteristics of signal intensity in first to fourth bands of reflected ultrasonic waves. [Figure 6] 1 is a diagram showing a transmitted wave from an ultrasonic probe and a reflected wave from a reflecting surface; [Figure 7] FIG. 10 is a diagram showing high-intensity positions of reflected waves when the imaging frequency is changed. [Figure 8] 1 is a diagram showing a transmitted wave from an ultrasonic probe and a scattered wave from a scattering source; [Figure 9] (a) is a diagram showing scattered waves and interference waves in phase, (b) is a diagram showing scattered waves and interference waves in opposite phase, and (c) is a diagram showing scattered waves and interference waves with the imaging frequency lowered from (a). [Figure 10] 1A is a diagram showing an example of an ultrasound image with few scattered artifacts, and FIG. 1B is a diagram showing an example of an ultrasound image with many scattered artifacts. [Figure 11] FIG. 2 is a diagram showing an ultrasound probe, a scattering source, and a virtual image of the scattering source. [Figure 12] 10 is a flowchart showing a first ultrasound image display process. [Figure 13] FIG. 1 is a diagram showing an ultrasound image, a cross-calculation image, and a simple average image. [Figure 14] 14(a) is a diagram showing brightness values at a predetermined distance including the brightest point of the wire target in the ultrasound image of Fig. 13. FIG. 14(b) is a diagram showing brightness values at a predetermined distance including the brightest point of the wire target in the ultrasound image of Fig. 13. FIG. 14(c) is a diagram showing brightness values at a predetermined distance including the brightest point of the wire target in the mutual operation image of Fig. 13. [Figure 15] 1A and 1B are diagrams showing an ultrasound image, a binarized image, a cross-operation image, and a binarized cross-operation image. [Figure 16] FIG. 10 is a diagram illustrating an example of an LUT. [Figure 17] 15A and 15B are diagrams showing the mutual operation image and binarized mutual operation image of FIG. 14, and the mutual operation image and binarized mutual operation image after LUT conversion. [Figure 18] FIG. 5 is a diagram showing a side-by-side display of the ultrasound image and the cross-calculated image of FIG. 4. [Figure 19] FIG. 5 is a diagram showing a side-by-side display of the cross-operation image and the difference image of FIG. 4. [Figure 20] FIG. 10 is a block diagram showing a schematic configuration of an ultrasound diagnostic apparatus according to a second embodiment. [Figure 21] 10 is a flowchart showing a second ultrasound image display process. [Figure 22] FIG. 10 is a block diagram showing a schematic configuration of an ultrasonic diagnostic apparatus according to a third embodiment. [Figure 23] 10 is a flowchart showing a third ultrasound image display process. [Figure 24] 1A and 1B are diagrams showing ultrasound images with different delay-and-sum conditions; [Figure 25] FIG. 25 shows a watershed segmented image corresponding to the ultrasound image of FIG. 24. [Figure 26] 10 is a flowchart showing a fourth ultrasound image display process. DETAILED DESCRIPTION OF THE INVENTION

[0034] First to third embodiments of the present invention will be described in detail in order with reference to the accompanying drawings, however, the present invention is not limited to the illustrated examples.

[0035] (First embodiment) A first embodiment of the present invention will be described with reference to FIGS. 1 to 19. First, the device configuration of an ultrasound diagnostic device 100A according to this embodiment will be described with reference to FIGS. 1 to 8. FIG. 1 is a diagram showing the external configuration of the ultrasound diagnostic device 100A according to this embodiment. FIG. 2 is a block diagram showing the schematic configuration of the ultrasound diagnostic device 100A. FIG. 3 is a block diagram showing the functional configuration of the transmission unit 12. FIG. 4(a) is a diagram showing the frequency characteristics of the signal strength of transmitted ultrasound. FIG. 4(b) is a diagram showing the frequency characteristics of the signal strength of reflected ultrasound. FIG. 5 is a diagram showing the frequency characteristics of the signal strength of bands B1 to B4 of the reflected ultrasound.

[0036] An ultrasound diagnostic device 100A according to this embodiment is installed in a medical facility such as a hospital, and includes an ultrasound diagnostic device main body 1A and an ultrasound probe 2, as shown in FIGS. 1 and 2. The ultrasound probe 2 transmits ultrasound waves (transmitted ultrasound waves) to a subject such as a living organism (not shown), and receives reflected waves of the ultrasound waves (reflected ultrasound waves: echoes) reflected by the subject. The ultrasound probe 2 includes an ultrasound probe main body 21, a cable 22, and a connector 23. The ultrasound probe main body 21 is a header portion of the ultrasound probe 2 that transmits and receives ultrasound waves. The cable 22 is connected between the ultrasound probe main body 21 and the connector 23, and is a cable through which a drive signal for the ultrasound probe main body 21 and an ultrasound reception signal flow. The connector 23 is a plug connector for connecting to a receptacle connector (not shown) of the ultrasound diagnostic device main body 1A.

[0037] The ultrasound diagnostic device main body 1A is connected to the ultrasound probe main body 21 via a connector 23 and a cable 22, and transmits an electrical drive signal to the ultrasound probe main body 21 to cause the ultrasound probe main body 21 to transmit ultrasound waves to the subject, and also images the internal state of the subject as ultrasound image data based on a reception signal, which is an electrical signal generated by the ultrasound probe 2 in response to ultrasound waves reflected from within the subject and received by the ultrasound probe main body 21. Communication between the ultrasound diagnostic device main body 1A and the ultrasound probe 2 (ultrasound probe main body 21) may be performed by wireless communication such as UWB (Ultra Wide Band) instead of wired communication via the cable 22.

[0038] As shown in FIG. 2, the ultrasonic probe body 21 includes a plurality of transducers 2a each made of a piezoelectric element, and the transducers 2a are arranged, for example, in a one-dimensional array in the azimuth direction. In this embodiment, an ultrasonic probe 2 including, for example, 192 transducers 2a is used. The transducers 2a may be arranged in a two-dimensional array. The number of transducers 2a can be set arbitrarily. In this embodiment, a linear scanning electronic scan probe is used for the ultrasonic probe 2, but either an electronic scanning system or a mechanical scanning system may be used, and any of a linear scanning system, a sector scanning system, or a convex scanning system may also be used.

[0039] The ultrasonic probe 2 used in the present invention is not limited to a specific frequency value, but preferably has a wide bandwidth. With a narrow bandwidth, when performing mutual calculations on band-divided image signals, the correlation difference between the high-correlation image signal due to reflecting tissue and the low-correlation image signal due to tissue scattering and interference becomes small, making it difficult to achieve a sufficient low-correlation signal suppression effect. Specifically, the bandwidth should be at least 100% or more, and preferably 120% or more, of the -20 dB frequency fractional bandwidth, which is the realistic effective transmission / reception bandwidth of image signals.

[0040] As shown in FIG. 2, the ultrasound diagnostic device main body 1A includes, for example, an operation input unit 11, a transmitting unit 12, a receiving unit 13, a sound ray signal generating unit 14A, a signal processing unit 15A, a DSC (Digital Scan Converter) 16 as an image data generating unit, an image processing unit 17A as first and second display control units, a display unit 18, and a control unit 19A.

[0041] The operation input unit 11 has operation elements such as various switches, buttons, a trackball, a mouse, a keyboard, a touchpad, and a multifunction switch for inputting commands from users such as doctors and technicians to start a diagnosis, and data such as personal information of the subject, etc. The operation input unit 11 accepts operation inputs from the user via the operation elements and outputs the operation signals to the control unit 19A.

[0042] The transmitting unit 12 is a circuit that, under the control of the control unit 19A, supplies a drive signal, which is an electrical signal, to the ultrasonic probe main body 21 via a cable 22 and a connector 23, causing the ultrasonic probe 2 to generate transmitted ultrasonic waves. As shown in FIG. 3 , the transmitting unit 12 includes, for example, a clock generating circuit 121, a pulse generating circuit 122, a time and voltage setting unit 123, and a delay circuit 124.

[0043] The clock generation circuit 121 is a circuit that generates a clock signal that determines the transmission timing and transmission frequency of the drive signal. The pulse generation circuit 122 is a circuit that generates a pulse signal as a drive signal at a predetermined cycle. The pulse generation circuit 122 can generate a square wave drive signal by switching and outputting, for example, three-value (+HV / 0 (GND) / -HV) or five-value (+HV / +MV / 0 (GND) / -MV / -HV) voltages. In this case, the amplitude of the pulse signal is the same for positive and negative polarities, but is not limited to this. In this embodiment, the drive signal is output by switching between three-value and five-value voltages. However, the number of values is not limited to three or five and can be set to any appropriate value, although five values or less is preferable. This allows for improved freedom of control of frequency components at low cost, and enables transmission ultrasound with higher resolution to be obtained.

[0044] The time and voltage setting unit 123 sets the duration and voltage level of each section of the drive signal output from the pulse generating circuit 122, which has the same voltage level. That is, the pulse generating circuit 122 outputs a drive signal having a pulse waveform in accordance with the duration and voltage level of each section set by the time and voltage setting unit 123. The duration and voltage level of each section set by the time and voltage setting unit 123 can be varied, for example, by inputting data via the operation input unit 11.

[0045] The delay circuit 124 is a circuit that sets a delay time for the transmission timing of the drive signal for each individual path corresponding to each transducer 2a, and delays the transmission of the drive signal by the set delay time to focus the transmission beam formed by the transmitted ultrasound.

[0046] The transmitting unit 12 configured as described above sequentially switches among the multiple transducers 2a to which the drive signals are supplied, shifting them by a predetermined number for each transmission and reception of ultrasound waves, under the control of the control unit 19A, and performs scanning by supplying drive signals to the multiple transducers 2a whose outputs are selected.

[0047] In this embodiment, a pulse inversion method can be implemented to extract harmonic components, which will be described later. That is, when implementing the pulse inversion method, the transmitter 12 can transmit a first pulse signal and a second pulse signal, the polarity of which is inverted from that of the first pulse signal, on the same scanning line at a time interval. In this case, the second pulse signal, the polarity of which is inverted by changing at least one of the multiple duties of the first pulse signal, may be transmitted. Furthermore, the second pulse signal may be time-inverted from the first pulse signal.

[0048] The receiving unit 13 is a circuit that receives an electric reception signal from the ultrasonic probe 2 (from the ultrasonic probe main body 21 via the cable 22 and the connector 23) under the control of the control unit 19A.

[0049] The sound ray signal generating unit 14A is a circuit that generates sound ray signals from the reception signals received by the receiving unit 13 under the control of the control unit 19A. The sound ray signal generating unit 14A includes, for example, an amplifier, an A / D conversion circuit, and a phasing addition circuit, together with a harmonic component extracting unit 14a.

[0050] The amplifier is a circuit for amplifying the reception signal received by the receiving unit 13 by a predetermined amplification factor set in advance for each individual path corresponding to each transducer 2a. The A / D conversion circuit is a circuit for analog-to-digital conversion (A / D conversion) of the amplified reception signal. The phasing addition circuit is a circuit for adjusting the time phase by providing a delay time for each individual path corresponding to each transducer 2a to the A / D converted reception signal, and for adding these (phasing addition) to generate a digital sound ray signal (sound ray data).

[0051] The harmonic component extraction unit 14a extracts harmonic components from the generated sound ray signal by pulse inversion under the control of the control unit 19A. In this embodiment, the harmonic component extraction unit 14a can extract signal components mainly consisting of second harmonics. The second harmonic component can be extracted by adding (combining) the received signals obtained from the reflected ultrasonic waves corresponding to the two transmitted ultrasonic waves generated from the first and second pulse signals, respectively, removing the fundamental wave component contained in the received signals, and then performing filtering. Furthermore, when odd-order harmonic components such as third harmonics are used, the harmonic components can be extracted by subtracting the first and second received signals corresponding to the first and second pulse signals and then removing the fundamental wave component using a filter or the like. Furthermore, both the even-order harmonic components obtained by addition and the odd-order harmonic components obtained by subtraction can be used. In this case, the odd-order harmonic received signal is phase-adjusted using an all-pass filter or the like to match the phase with the even-order harmonic received signal, and then added (synthesized) before envelope detection at the received signal stage. This combines the frequency bands of the even-order harmonic received signal and the odd-order harmonic received signal, making it possible to obtain a received signal with a wider bandwidth.

[0052] For example, as shown in Fig. 4(a), the transmitter 12 generates a drive signal for transmitting transmitted ultrasonic waves including fundamental waves f1, f2, and f3. In Fig. 4(a), the horizontal axis represents frequency, the vertical axis represents signal strength (sensitivity) of the transmitted ultrasonic waves, and the thick solid line represents the frequency band of the ultrasonic probe 2. This is also true for the diagram of signal strength of reflected ultrasonic waves in Fig. 4(b).

[0053] As the frequency components of the received signal obtained by the receiving unit 13 and the sound ray signal generating unit 14A, the harmonic components of the reflected ultrasonic waves corresponding to the transmitted ultrasonic waves of fundamental waves f1, f2, and f3 are as shown in Fig. 4(b). That is, as the harmonic components of the reflected ultrasonic waves, frequency components of f3-f2, f2-f1, f3-f1, 2f1, f1+f2, and 3f1 derived from at least one of the fundamental waves f1, f2, and f3 are obtained. The sound ray signal generating unit 14A generates a sound ray signal including all the frequency components shown in Fig. 4(b).

[0054] The signal processing unit 15A has imaging signal extraction units 15a1 to 15an (n: a natural number equal to or greater than 2) as imaging signal generation units, an imaging signal calculation unit 15b as a calculation unit, and an image signal analysis unit 15c as an analysis unit. Under the control of the control unit 19A, the signal processing unit 15A extracts signals from n frequency bands from the sound ray signals input from the harmonic component extraction unit 14a to generate first to n-th imaging signals, performs calculations such as mutual calculation on the first to n-th imaging signals to generate mutual calculation imaging signals, and performs analysis processing using the normal imaging signals of a normal image that is not subjected to mutual calculation (an image before mutual calculation is performed) and the mutual calculation imaging signals.

[0055] The imaging signal extraction units 15a1 to 15an are circuits that include first to n-th band-pass filters that pass received signals in first to n-th frequency bands, respectively, and extract first to n-th imaging signals by passing frequency components from the sound ray signal input from the harmonic component extraction unit 14a using the band-pass filters under the control of the control unit 19A. For example, the imaging signal extraction unit 15a1 outputs a first imaging signal that has passed frequency components in the frequency band (full band) of the ultrasound probe 2 using the first band-pass filter. The imaging signal extraction units 15a2 to 15an output second to n-th imaging signals that have passed frequency components in a frequency band smaller than the full band using the second to n-th band-pass filters, respectively. The first imaging signal has the highest content of high-frequency components.

[0056] The cutoff characteristics of the multiple different bandpass filters of the imaging signal extraction units 15a1-15an are determined appropriately for each type of ultrasound probe 2 depending on its acoustic characteristics and the object of observation, and multiple combinations of these may be prepared. The multiple combinations may be selected automatically or manually, such as by automatically selecting the filter in conjunction with the user's selection of the object of observation (such as a region of the subject) via the operation input unit 11, by detecting features from the imaging signals and adaptively selecting the filter based on their evaluation values, or by the user inputting a selection via the operation input unit 11 as needed. These bandpass filters may not be fixed filters, but may be so-called dynamic filters whose cutoff characteristics continuously change depending on the depth.

[0057] For example, assuming n=4, the imaging signal extraction unit 15a1 filters the sound ray signals generated by the sound ray signal generation unit 14A using a first band-pass filter of band B1 of the full band indicated by a thick solid line in Fig. 5, which passes all frequency components, to generate a first imaging signal. Here, the imaging signal corresponding to band B1 of the full band extracted by the imaging signal extraction unit 15a1 corresponds to a normal image and is referred to as a normal imaging signal. However, an imaging signal generated by the sound ray signal generation unit 14A without filtering by the imaging signal extraction units 15a1 to 15an may also be referred to as a normal imaging signal.

[0058] The imaging signal extraction unit 15a2 filters the sound ray signals generated by the sound ray signal generation unit 14A using a second band-pass filter of low-frequency band B2, shown by a dotted line in Fig. 5, to generate a second imaging signal. The imaging signal extraction unit 15a3 filters the sound ray signals generated by the sound ray signal generation unit 14A using a third band-pass filter of band B3, shown by a dotted line, which has a higher frequency than band B3, to generate a third imaging signal. The imaging signal extraction unit 15a4 filters the sound ray signals generated by the sound ray signal generation unit 14A using a fourth band-pass filter of band B4, shown by a dotted line, which has a higher frequency than band B3, to generate a fourth imaging signal.

[0059] The imaging signal calculation unit 15b performs a mutual calculation on the first to n-th imaging signals for generating B (Brightness) mode image data generated by the imaging signal extraction units 15a1 to 15an under the control of the control unit 19A to generate a mutual calculation imaging signal. This is an operation that utilizes the difference in correlation when the frequency changes in an image to suppress scattered components corresponding to ultrasound waves scattered by scattering sources (microscatterers) in the subject (leaving reflected components corresponding to ultrasound waves reflected by tissues (reflectors) in the subject, etc.). This mutual operation, as will be described later, utilizes the fact that reflected components in high-intensity areas appear when the brightness correlation at the same point (same position) in multiple ultrasound images is high, and scattered components in low-intensity areas appear when the brightness correlation at the same position is low, and suppresses them using "multiplication," which has a light processing load. Multiplication of the first to nth imaging signals is a process of multiplying brightness values corresponding to pixels at the same position in each B-mode image of the first to nth imaging signals. Therefore, if even one brightness value corresponding to a pixel at the same position in the first to nth imaging signals is 0 (corresponding to black), the multiplication result will be 0.

[0060] Furthermore, the imaging signal calculation unit 15b performs a gradation adjustment restoration process on the generated mutually calculated imaging signal under the control of the control unit 19A. The gradation adjustment restoration process is, for example, a power root operation process or a look-up table (LUT) conversion process. When multiplication is used in the mutual calculation of the imaging signal calculation unit 15b, converting the multiplied value directly into a brightness value will emphasize only high-brightness areas, resulting in an image with poor tissue visibility. Therefore, it is preferable to perform a gradation adjustment restoration process. Specifically, a power root operation according to the number of mutually calculated images can be performed. For example, if the number of multiplied images is 3, a cube root operation is performed on the multiplied value. Alternatively, if n=4 and the number of multiplied images is 4, a fourth root operation is performed, as shown in FIG. 5. Alternatively, instead of performing sequential calculations, a gradation adjustment restoration method using an equivalent LUT and LUT conversion process can be used. This LUT is assumed to be generated in advance and stored in a storage unit (not shown) such as a ROM (Read Only Memory) of the control unit 19A or an HDD (Hard Disk Drive) or SSD (Solid State Drive) of the ultrasound diagnostic apparatus 100A.

[0061] The image signal analyzer 15c analyzes the mutually-operated imaging signal calculated by the imaging signal calculator 15b under the control of the controller 19A. This analysis includes a process of calculating the difference between the normal imaging signal and the mutually-operated imaging signal to generate a differential imaging signal of a differential image. The process of calculating the difference between the imaging signals involves subtracting the brightness value of each pixel in the normal image of the normal imaging signal from the brightness value of the pixel at the same position in the mutually-operated imaging signal. This differential image is an image depicting the scattered component. The analysis also includes a process of generating an index value based on the differential image of the generated differential imaging signal. The index value based on this differential image is, for example, information for diagnosing the patient. Specific examples of the index value based on the differential image include statistical information such as the average difference value and the variance of the difference values within a region of interest (ROI) set by the user via the operation input unit 11. Multiple regions of interest (ROIs) may be set, and the index value may be a ratio of statistical values (average difference value, variance of difference value) within multiple ROIs. By displaying this index value, the user can know the amount and ratio of scattered components within the region of interest. Furthermore, this index value is expected to be used as information on the amount of intramuscular fat for each part of skeletal muscle, for example, and may be used to assess the effectiveness of rehabilitation by tracking the progress of the same part.

[0062] The ultrasonic transmission and reception method for generating a B-mode image to which the present invention is applied is not particularly limited to the harmonic imaging mode described above, but is preferably a method capable of receiving high contrast and wideband signals. Specifically, harmonic imaging is preferred, which is less likely to generate artifacts such as side lobes due to the sound pressure dependence of harmonic generation and can obtain high-contrast image signals. Among these, it is preferable to use methods such as those described in Japanese Patent Nos. 6326716, 6443217, and 6540838, which can obtain wideband received signals from shallow to deep areas. This makes it possible to obtain wideband received signals from shallow to deep areas, and maintain a high level of low-correlation signal suppression effect through mutual calculation of multiple images obtained by band division.

[0063] The DSC 16 receives the image signal from the imaging signal extraction unit 15a1 under the control of the control unit 19A. The normal imaging signal as the acoustic ray signal input from the imaging signal calculation unit 15b, the mutual calculation imaging signal as the acoustic ray signal input from the image signal analysis unit 15c are subjected to envelope detection processing and logarithmic compression, and the dynamic range and gain are adjusted to convert the luminance, and if necessary, polar coordinate conversion and display pixel interpolation calculation are performed to generate normal image data, mutual calculation image data, and differential image data as B-mode image data for display, respectively. The B-mode image data represents the strength of the received signal by luminance.

[0064] The image processing unit 17A is a circuit that performs image processing on normal image data, mutual calculation image data, and differential image data input from the DSC 16, and index values based on the differential image input from the image signal analysis unit 15c via the DSC 16, under the control of the control unit 19A, and has a display image synthesis unit 17a and an image analysis display value generation unit 17b.

[0065] The display image synthesis unit 17a is a circuit that, under the control of the control unit 19A, synthesizes at least two of the following data in parallel: normal image data and mutual calculation image data input from the DSC 16, and differential image data for display and index values based on the differential image for display input from the image analysis display value generation unit 17b, as described below, to generate synthetic image data for display.

[0066] The image analysis display value generator 17b is a circuit that generates differential image data for display from differential image data input from the DSC 16 under the control of the controller 19A. For example, the image analysis display value generator 17b applies color to each pixel of the differential image data according to the differential value, and uses the colored differential image data as differential image data for parametric display. The image analysis display value generator 17b also generates index values based on the differential image for display from index values based on the differential image input from the image signal analyzer 15c via the DSC 16.

[0067] Display devices such as an LCD (Liquid Crystal Display), a CRT (Cathode-Ray Tube) display, an organic EL (Electronic Luminescence) display, an inorganic EL display, and a plasma display are applicable to the display unit 18. The display unit 18 displays an ultrasound image or the like on the display screen in accordance with display signals such as image data and composite image data input from the image processing unit 17A under the control of the control unit 19A.

[0068] The control unit 19A includes, for example, a CPU (Central Processing Unit), ROM, and RAM (Random Access Memory), reads various processing programs such as a system program stored in the ROM, expands them into the RAM, and centrally controls the operation of each unit of the ultrasonic diagnostic device 100A according to the expanded programs. The ROM is configured with non-volatile memory such as a semiconductor, and stores the system program corresponding to the ultrasonic diagnostic device 100A, various processing programs executable on the system program, and various data. These programs are stored in the form of computer-readable program code, and the CPU sequentially executes operations according to the program code. The ROM particularly stores a first ultrasonic image display program for executing a first ultrasonic image display process described below. The RAM forms a work area for temporarily storing various programs executed by the CPU and data related to these programs.

[0069] For each part of the ultrasound diagnostic device main body 1A, some or all of the functions of each functional block can be realized as a hardware circuit such as an integrated circuit. An integrated circuit is, for example, an LSI (Large Scale Integration), and LSIs are classified into IC It is also called system LSI, super LSI, or ultra LSI. The method of integration is not limited to LSI, but can be realized by dedicated circuits or general-purpose processors, or by FPGA (Field Programmable Gate Array) or the connection of circuit cells inside LSI. A reconfigurable processor that can reconfigure the settings may be used. Some or all of the functions of the functional blocks may be implemented by software, which is stored in one or more storage media such as ROMs, optical disks, or hard disks, and executed by a processor.

[0070] Here, the correlation difference between the reflected signal and the scattered signal of an ultrasound image will be described with reference to Figs. 6 to 11. Fig. 6 is a diagram showing the transmitted wave T1 from the ultrasound probe 2 and the reflected waves RWa and RWb from the reflecting surfaces RSa and RSb. Fig. 7 is a diagram showing high-intensity positions of the reflected waves RWa and RWb when the imaging frequency is changed. Fig. 8 is a diagram showing the transmitted wave T1 from the ultrasound probe 2 and the scattered waves SWa and SWb from the scattering sources SCa and SCb.

[0071] FIG. 9(a) is a diagram showing in-phase scattered waves SWa1 and SWb1 and an interference wave IW1. FIG. 9(b) is a diagram showing out-of-phase scattered waves SWa2 and SWb2 and an interference wave IW2. FIG. 9(c) is a diagram showing scattered waves SWa3 and SWb3 with imaging frequencies lowered from FIG. 9(a) and an interference wave IW3. FIG. 10(a) is a diagram showing an example of an ultrasound image with few scattered virtual images. FIG. 10(b) is a diagram showing an example of an ultrasound image with many scattered virtual images. FIG. 11 is a diagram showing the ultrasound probe 2, scattering sources SC1, SC2, and SC3, and virtual images V1, V2, and V3 of the scattering sources SC1, SC2, and SC3.

[0072] 6, consider a case in which an ultrasound probe 2 transmits a transmission wave T1 as a transmission ultrasound to a subject, the transmission wave T1 is reflected by reflecting surfaces RSa and RSb of reflectors such as tissue of the subject at different depths, and is received as a received wave by the ultrasound probe 2. The reflected ultrasound reflected by reflecting surface RSa is a reflected wave RWa as a received wave, and the reflected ultrasound reflected by reflecting surface RSb is a reflected wave RWb as a received wave. Furthermore, the width in the traveling direction of the transmission wave T1 is a pulse width p, and the distance in the depth direction between reflecting surfaces RSa and RSb is a distance X.

[0073] The distance between the reflected waves RWa and RWb is 2X. When 2X>p, the reflected waves RWa and RWb are received by the ultrasonic probe 2 without interference and are imaged as brightness points according to their pulse widths and amplitudes.

[0074] As shown in Figure 7, consider the case where the imaging frequency of the reflected waves RWa and RWb is changed to three levels: low, medium, and high. When the reflecting surfaces RSa and RSb are located at a distance significantly greater than the wavelength (pulse width p), their reflectivity is determined by the acoustic impedance and remains constant even when the imaging frequency is changed. Furthermore, there is no interference or cancellation between the pulses (reflected waves RWa and RWb). Therefore, the high-intensity positions of the reflected wave RWa when the imaging frequency is changed to low, medium, and high remain the same, and the high-intensity positions of the reflected wave RWb when the imaging frequency is changed to low, medium, and high remain the same. Therefore, there is a high correlation between the brightness at the same position.

[0075] Next, as shown in Fig. 8, consider a case in which an ultrasound probe 2 transmits a transmission wave T1 as a transmission ultrasound to a subject, the transmission wave T1 is scattered by scattering sources SCa and SCb in the subject at different depths, such as dense scattering sources, and is received by the ultrasound probe 2 as a received wave. The ultrasound (echo) scattered by scattering source SCa is referred to as a scattered wave SWa as a received wave, and the ultrasound scattered by scattering source SCb is referred to as a scattered wave SWb as a received wave. Furthermore, the width in the traveling direction of the transmission wave T1 is referred to as a pulse width p, and the distance in the depth direction between scattering sources SCa and SCb is referred to as a distance X.

[0076] The distance between the scattered waves SWa and SWb is the distance 2X. When 2X < p, the scattered waves SWa and SWb are received by the ultrasonic probe 2 as an interference (synthesis) result and imaged as luminance points reflecting their interference.

[0077] As shown in Fig. 9(a), let the imaging frequency be the frequency f, and the scattered waves SWa and SWb are made to interfere in the same phase to generate an interference wave IW1. For the interference wave IW1, the distance 2X is taken so that the scattered waves SWa and SWb are combined (in the same phase), and the highest luminance with the largest amplitude of the interference wave IW1 is obtained at the position shown in Fig. 9(a).

[0078] As shown in Fig. 9(b), the scattered waves SWa and SWb are made to interfere in the opposite phase to generate an interference wave IW2. For the interference wave IW2, the distance 2X is taken so that the scattered waves SWa and SWb cancel each other out (in the opposite phase). Thus, due to the phase relationship at the time of interference (the relationship between the distance 2X and the wavelength (pulse width p)), the amplitude (image luminance) of the interference wave IW2 varies greatly.

[0079] As shown in Fig. 9(c), the imaging frequency is made lower than the frequency f, and the scattered waves SWa and SWb are made to interfere in the opposite phase to generate an interference wave IW3. The distance 2X corresponding to the interference wave IW3 is the same as the distance 2X corresponding to the interference wave IW1, but since the imaging frequency is lower than the frequency f, the scattered waves SWa and SWb cancel each other out. The interference wave IW3 has the lowest luminance at the same position as the position of the highest luminance of the interference wave IW1. Thus, when the distance 2X is the same, due to the change in the imaging frequency, the combination / cancellation of the interference waves changes, so the luminance correlation at the same position is low.

[0080] Next, the reception of scattered waves when scattering sources are sparse will be described. Comparing an ultrasound image with few scattered virtual images (virtual images of scattering sources caused by scattered waves) as shown in Fig. 10(a) with an ultrasound image with many scattered virtual images as shown in Fig. 10(b), the ultrasound image in Fig. 10(a) has good visualization of dark areas, while the ultrasound image in Fig. 10(b) has poor visualization of dark areas. Therefore, it is preferable to suppress scattered virtual images.

[0081] As shown in Figure 11, consider a case in which ultrasonic waves (ultrasonic beams) are transmitted from ultrasonic probe 2 to a subject, scattered by scattering sources SC1, SC2, and SC3 in the medium of the subject, and these scattered waves are received as received waves by ultrasonic probe 2. The transmitted ultrasonic waves from ultrasonic probe 2 pass through the acoustic line center (main scanning line) A1 and are transmitted with transmission focal point F1 as the focal point. In addition, multiple arrows pointing from the transmitted composite wavefront TW of the transmitted ultrasonic waves indicate the progression of the composite wavefront.

[0082] It is known that the reflectivity of a minute scatterer when the scattering source is smaller than the wavelength of the ultrasound is proportional to the fourth power of the frequency (see Ultrasonic Technology Handbook (revised edition)). For this reason, when the frequency of the transmitted ultrasound changes, the way the scattering is received changes, and so the path of the scattered ultrasound (scattered waves) changes. In Figure 11, the path of ultrasound with a high frequency corresponding to the transmitted ultrasound from the ultrasound probe 2 is shown by a dashed-dotted arrow as the high-frequency scattering path, the path of ultrasound with a medium frequency corresponding to the transmitted ultrasound is shown by a dashed-two-dotted arrow as the medium-frequency scattering path, and the path of ultrasound with a low frequency corresponding to the transmitted ultrasound is shown by a solid-line arrow as the low-frequency scattering path.

[0083] Assume that high-frequency transmitted ultrasound is scattered by scattering source SC1, medium-frequency transmitted ultrasound is scattered by scattering source SC2, and low-frequency transmitted ultrasound is scattered by scattering source SC3, and these scattered waves are received by transducer 2a at the acoustic line center A1. Then, in an ultrasound image generated by ultrasound containing the received scattered waves, a virtual image V1 of scattering source SC1, a virtual image V2 of scattering source SC2, and a virtual image V3 of scattering source SC3 appear. The virtual images V1, V2, and V3 are located at different depth directions. Therefore, when the ultrasound frequencies are different, the positional correlation of the virtual images caused by the scattering sources is low. Furthermore, the positional correlation of the virtual images caused by side lobes also decreases as the pitch of the Sinc function changes with changes in the ultrasound frequency.

[0084] Therefore, for multiple ultrasound images (imaging signals) with different imaging frequencies, the brightness correlation at the same position is calculated by multiplying the brightness values of pixels at the same position as a mutual operation. It is possible to generate an ultrasound image (imaging signal) that suppresses the brightness values of pixels based on scattered waves with low brightness correlation at the same position (dark area visualization) while leaving the brightness values of pixels based on reflected waves with high brightness correlation intact.

[0085] Next, the operation of the ultrasound diagnostic device 100A will be described with reference to FIGS. 12 to 19. FIG. 12 is a flowchart showing the first ultrasound image display process. FIG. 13 is a diagram showing ultrasound images I1 to I4, a mutual calculation image I5, and a simple average image I6. FIG. 14(a) is a diagram showing brightness values at a predetermined distance including the highest brightness point of the wire target in ultrasound image I1 of FIG. 13. FIG. 14(b) is a diagram showing brightness values at a predetermined distance including the highest brightness point of the wire target in ultrasound image I2 of FIG. 13. FIG. 14(c) is a diagram showing brightness values at a predetermined distance including the highest brightness point of the wire target in mutual calculation image I5 of FIG. 13. FIG. 15 is a diagram showing ultrasound images I11 to I14, binarized images I21 to I24, mutual calculation image I15, and binarized mutual calculation image I25. FIG. 16 is a diagram showing an example of an LUT. Fig. 17 is a diagram showing the mutual operation image I15 and binarized mutual operation image I25 of Fig. 14, and the mutual operation image I35 and binarized mutual operation image I45 after LUT conversion. Fig. 18 is a diagram showing a side-by-side display of the ultrasound image I11 and the mutual operation image I15 of Fig. 4. Fig. 19 is a diagram showing a side-by-side display of the mutual operation image I15 and difference image I51 of Fig. 4.

[0086] The first ultrasonic image display process executed by the ultrasonic diagnostic device 100A will be described with reference to Fig. 12. The first ultrasonic image display process is a process for generating a mutually calculated imaging signal from imaging signals of a plurality of ultrasonic images with different imaging conditions, and displaying a mutually calculated image, etc.

[0087] In the ultrasound diagnostic device 100A, the control unit 19A accepts input of various setting information for ultrasound image display from a user such as a doctor or technician via the operation input unit 11, and stores the input setting information in a RAM or a storage unit (not shown) of the control unit 19A in advance. The input setting information includes information on the content of gradation adjustment processing to be performed on the mutual calculation image (mutual calculation imaging signal), information on whether to simultaneously display the mutual calculation image with the normal image, information on whether to generate a difference image between the mutual calculation image and the normal image, information on whether to display the difference image, and information on whether to generate an index value based on the difference image.

[0088] In the ultrasound diagnostic device 100A, the control unit 19A executes the first ultrasound image display process in accordance with the first ultrasound image display program stored in the ROM, triggered, for example, by a user inputting an instruction to execute the first ultrasound image display process via the operation input unit 11. Note that the flowchart in Fig. 12 shows the flow of generating and displaying one frame of ultrasound image data, and this flow will be explained, but in reality, for example, a configuration in which multiple frames of ultrasound image data are continuously generated and displayed as a live ultrasound image display may also be used, and this is the same as in Figs. 21, 23, and 26 described later.

[0089] As shown in FIG. 12, first, the control unit 19A causes the transmission unit 12 to generate a drive signal for tissue harmonic imaging including the three fundamental wave components shown in FIG. 4(a) for pulse inversion, and causes the ultrasound probe 2 to transmit ultrasound waves corresponding to the drive signal to the subject (step S11).

[0090] Then, the control unit 19A causes the receiving unit 13 to receive reflected ultrasonic waves that are the ultrasonic waves transmitted in step S11 and reflected and scattered by the subject to generate a received signal, and causes the sound ray signal generating unit 14A to perform amplification, A / D conversion, and phasing addition on the generated received signal to generate a sound ray signal containing harmonic components of the three fundamental wave components (step S12).The control unit 19A then causes the harmonic component extracting unit 14a to extract harmonic components from the sound ray signal generated in step S12 using a pulse inversion method, and generates a sound ray signal from which the harmonic components have been extracted (step S13).

[0091] Then, the control unit 19A causes the imaging signal extraction unit 15a1 to pass the sound ray signal generated in step S13 through a first band-pass filter that passes a predetermined frequency band (band) as the first imaging condition, and generate a first imaging signal (normal imaging signal) (step S14).

[0092] Also, in parallel with step S14, the control unit 19A causes the imaging signal extraction unit 15a2 to pass the sound ray signal generated in step S13 through a second bandpass filter that passes a predetermined frequency band as a second imaging condition to generate a second imaging signal (step S15). Similarly, in parallel with step S14, the control unit 19A causes the imaging signal extraction units 15a2 to 15a(n-1) to generate third to (n-1)th imaging signals. Also, in parallel with step S14, the control unit 19A causes the imaging signal extraction unit 15an to pass the sound ray signal generated in step S13 through an nth bandpass filter that passes a predetermined frequency band as an nth imaging condition to generate an nth imaging signal (step S16).

[0093] Then, the control unit 19A causes the imaging signal calculation unit 15b to perform mutual calculation on the first to n-th imaging signals generated in steps S14 to S16 to generate a mutually calculated imaging signal (step S17). The mutual calculation here is assumed to be multiplication of the first to n-th imaging signals.

[0094] Then, the control unit 19A refers to the setting information stored in the RAM or a storage unit (not shown) and causes the imaging signal calculation unit 15b to perform a gradation adjustment process corresponding to the setting information on the mutual calculation imaging signal generated in step S17 (step S18). This gradation adjustment process is a gradation adjustment process using a power root calculation process, an LUT conversion process, etc.

[0095] Then, the control unit 19A determines whether or not to simultaneously display the mutual calculation image and the normal image according to the setting information referred to in step S18 (step S19). If the mutual calculation image and the normal image are to be simultaneously displayed (step S19; YES), the control unit 19A causes the DSC 16 to generate first image data (normal image data) and mutual calculation image data from the first imaging signal (normal imaging signal) generated in step S14 and the mutual calculation imaging signal after gradation adjustment decoding generated in step S18, and causes the display image synthesis unit 17a to generate synthesized image data in which the normal image and the mutual calculation image are arranged in parallel from the normal image data and the mutual calculation image data (step S20).

[0096] Then, the control unit 19A determines whether or not to generate a difference image according to the setting information referred to in step S18 (step S21). If the mutual calculation image and the normal image are not to be displayed simultaneously (step S19; NO), the process proceeds to step S21. If the difference image is to be generated (step S21; YES), the control unit 19A causes the image signal analysis unit 15c to take the difference between the first imaging signal (normal imaging signal) generated in step S14 and the mutual calculation imaging signal after the gradation adjustment demodulation process generated in step S18, thereby generating a difference imaging signal (step S22).

[0097] Then, the control unit 19A determines whether or not to display a difference image according to the setting information referred to in step S18 (step S23). Step S23 can determine YES if at least step S22 has been executed. If a difference image is not to be generated (step S21; NO), the process proceeds to step S23. If a difference image is to be displayed (step S23; YES), the control unit 19A causes the DSC 16 to generate mutual calculation image data from the mutual calculation imaging signal after gradation adjustment processing generated in step S18, generates difference image data from the difference imaging signal generated in step S22, causes the image analysis display value generation unit 17b to color the generated difference image data to generate difference image data for display, and causes the display image synthesis unit 17a to perform mutual calculation image data from the mutual calculation image data and the difference image data for display. The image and the difference image are arranged in parallel to generate composite image data (step S24).

[0098] Then, the control unit 19A determines whether or not to display an index value based on the differential image according to the setting information referred to in step S18 (step S25). It is assumed that step S25 can determine YES when at least step S22 is executed. If the differential image is not to be displayed (step S23; NO), the process proceeds to step S25. If the index value based on the differential image is to be displayed (step S25; YES), the control unit 19A causes the image signal analysis unit 15c to calculate an index value based on the differential image from the differential imaging signal generated in step S22 (step S26). Then, the control unit 19A causes the DSC 16 to generate mutual calculation image data from the mutual calculation imaging signal after the gradation adjustment demodulation processing generated in step S18, causes the image analysis display value generation unit 17b to generate index values based on the differential image for display from index values based on the generated differential image, and causes the display image synthesis unit 17a to generate synthesized image data in which the index values based on the mutual calculation image and the differential image for display are arranged from the index values based on the mutual calculation image data and the differential image for display (step S27).

[0099] After step S27 is executed, or if the index value based on the difference image is not displayed (step S25; NO), the control unit 19A displays the composite image of the composite image data generated in steps S20, S24, and S27 on the display unit 18 (step S28), and ends the first ultrasound image display process. However, in step S28, if all of steps S19, S21, S23, and S25 are NO, the control unit 19A causes the DSC 16 to generate mutual calculation image data from the mutual calculation imaging signal after the gradation demodulation process generated in step S18, and displays the generated mutual calculation image of the mutual calculation image data on the display unit 18.

[0100] Next, examples of images in the first ultrasonic image display process will be described with reference to FIGS.

[0101] First, as shown in FIG. 13, an ultrasound image of ultrasound image data obtained by scanning a subject with a wire target placed in a phantom using ultrasound diagnostic device 100A, where n=4, will be described. In steps S14 to S16, ultrasound diagnostic device 100A generates imaging signals for ultrasound images I1, I2, I3, and I4 with different frequency bands as imaging conditions through a first ultrasound image display process. Ultrasound image I1 is an ultrasound image of band B1 (full band) in FIG. 4(b). Ultrasound image I2 is an ultrasound image of band B2 in FIG. 4(b). Ultrasound image I3 is an ultrasound image of band B3 in FIG. 4(b). Ultrasound image I4 is an ultrasound image of band B4 in FIG. 4(b). A grayscale chart of brightness values is included to the left of ultrasound images such as ultrasound image I1, and the brightness values are expressed as values ranging from 0 to 255, for example.

[0102] In step S17, the ultrasound diagnostic device 100A performs multiplication as a mutual operation on (imaging signals of) the ultrasound images I1, I2, I3, and I4, and in step S18 performs a power-root operation process of 4 as a scale adjustment decoding process to generate a mutual operation image I5. The ultrasound image I1 has fewer dark areas than the ultrasound images I2, I3, and I4. The mutual operation image I5 has more dark areas due to the suppression of scattered components compared to the ultrasound image I1, making the wire target (reflection component) easier to view.

[0103] The graph in Figure 14(a) shows the brightness values at a predetermined distance (30 pixels) including the brightest point of the wire target in ultrasound image I1. In the graph in Figure 14(a), the horizontal axis represents the pixel distance (pixels) from a predetermined position in the depth direction of the image, and the vertical axis represents the brightness value; this is also true for the graphs in Figures 14(b) and 14(c). The graph in Figure 14(b) shows the brightness values at a predetermined distance (30 pixels) including the brightest point of the wire target in ultrasound image I2. The graph in Figure 14(c) shows the brightness values at a predetermined distance (30 pixels) including the brightest point of the wire target in mutual operation image I5.

[0104] In the graphs of Figures 14(a) to 14(c), the point of maximum brightness where the brightness value is greatest corresponds to the center position of the wire target, and the narrower the width of the brightness peak, the higher the axial resolution of the image. Therefore, compared to ultrasound image I1 of full-band band B1, ultrasound image I2 of band B2, which is narrower than the full band, has lower axial resolution. However, mutual calculation image I5 has the same high axial resolution as ultrasound image I1.

[0105] Figure 13 shows simple average image I6, which is the simple average of the brightness values of each pixel in ultrasound images I1 to I4. In simple average image I6, the brightness values of the high-brightness areas of each pixel are smoothed, the low-brightness areas are filled in (poor clarity), there are few dark areas, the scattered components are not sufficiently suppressed, and the resolution is low. Compared to simple average image I6, mutual operation image I5, obtained by multiplication and power root operation without complex image processing, is able to suppress the brightness of the scattered components (matrix part) that was difficult to suppress in simple average image I6 (improved clarity) without substantially reducing the distance resolution of the wire target. Note that ultrasound images I1 to I4, mutual operation image I5, and simple average image I6 were images taken at a depth of approximately 1 cm, where the effect of suppressing the brightness of the scattered components in mutual operation image I5 is clearly evident without substantially reducing the distance resolution.

[0106] Next, as shown in FIG. 14, ultrasound images of ultrasound image data obtained by scanning a subject, which is pork, with n=4 using ultrasound diagnostic device 100A will be described. Ultrasound diagnostic device 100A generates ultrasound images I11, I12, I13, and I14 with different frequency bands as imaging conditions in steps S14 to S16 through the first ultrasound image display process. Ultrasound image I11 is an ultrasound image of band B1 (full band) in FIG. 4(b). Ultrasound image I12 is an ultrasound image of band B2 in FIG. 4(b). Ultrasound image I13 is an ultrasound image of band B3 in FIG. 4(b). Ultrasound image I14 is an ultrasound image of band B4 in FIG. 4(b).

[0107] In step S17, ultrasound diagnostic device 100A performs multiplication as a mutual operation on (imaging signals of) ultrasound images I11, I12, I13, and I14, and in step S18 performs a power-root operation process of 4 as a scale adjustment process to generate a mutual operation image I15. Ultrasound image I11 has fewer dark areas than ultrasound images I12, I13, and I14. Compared to ultrasound image I11, mutual operation image I15 has more dark areas due to the suppression of scattered components, making reflected components such as fascia more visible.

[0108] The binarized image I21 is an image in which the ultrasound image I11 has been binarized using a predetermined brightness threshold. The binarized images I21, I22, I23, and I24 and the binarized cross-operation image I25 are images in which the ultrasound images I11, I12, I13, and I14 and the cross-operation image I15 have been binarized using the same threshold as the binarized image I21. In the cross-operation image I15 and the binarized cross-operation image I25, the brightness (scattered component) between the subject's fascia is suppressed, and the continuity of the fascia (reflected component) is improved. Therefore, imaging by cross-operation of multiple ultrasound images with different frequency bands can be expected to be effective in suppressing the scattered component caused by intramuscular fat in elderly people, etc.

[0109] Next, an example will be described in which LUT conversion is performed on an ultrasound image of ultrasound image data obtained by scanning a subject, which is pork, using ultrasound diagnostic device 100A, where n=4. For LUT conversion, the LUT shown in Fig. 16 is used. This LUT indicates an output signal [%] relative to an input signal [%], and converts an input signal of 0 to 4 [%] into an output signal of 0 [%], and converts an input signal of 4 to 100 [%] into an output signal of 0 to 100 [%].

[0110] As in FIG. 15, the ultrasound diagnostic device 100A generates ultrasound images I11, I12, I13, and I14 in steps S14 to S16 through the first ultrasound image display process, and performs mutual operations on (the imaging signals of) the ultrasound images I11, I12, I13, and I14 in step S17. The mutual operation image I15 is generated by performing a power root operation of 4 as a scale adjustment restoration process in step S18 by performing all the multiplications. Fig. 17 shows the mutual operation image I15 and its binarized mutual operation image I25.

[0111] 17, ultrasound diagnostic device 100A generates ultrasound images I11, I12, I13, and I14 in steps S14 to S16 through a first ultrasound image display process, and performs LUT conversion processing using the LUT in FIG. 16. In step S17, ultrasound images I11, I12, I13, and I14 (imaging signals) are multiplied as a mutual operation, and then a power-root operation of four is performed as a step S18 to generate a mutual operation image I35. Also, binarized mutual operation image I45 is shown, which is binarized with the same threshold as binarized mutual operation image I25. The pixel ratio data of binarized mutual operation image I25 indicates that the pixel ratio of dark areas (black areas) within the ultrasound image region is 18%. The pixel ratio of dark areas (black areas) within the ultrasound image region of binarized mutual operation image I45 is 19%.

[0112] When performing mutual calculation, the imaging signal can be calculated as is, but to enhance the effect of low-correlation signal suppression, it is preferable to perform LUT conversion before calculation, setting input signals below a certain value to an output signal of 0%.It can be seen that mutual calculation image I35 and binary mutual calculation image I45 have greater suppression of low-correlation signal areas (scattered components) than mutual calculation image I15 and binary mutual calculation image I25, making the film-like high-correlation signal areas (reflected components) more visible.

[0113] Next, an example will be described in which a mutually calculated image of an ultrasound image of ultrasound image data obtained by scanning a subject, which is pork, is displayed in parallel with a normal image using ultrasound diagnostic device 100A, where n = 4. It is assumed that setting information for displaying the mutually calculated image simultaneously with the normal image has been stored in advance by operation input from the user via operation input unit 11.

[0114] As in FIG. 15, the ultrasound diagnostic device 100A generates ultrasound images I11, I12, I13, and I14 in steps S14 to S16 through the first ultrasound image display process, and in step S17, performs multiplication as a mutual operation on (the imaging signals of) the ultrasound images I11, I12, I13, and I14, and generates a mutual operation image I15 by performing a power-of-four operation process as a step-adjustment decoding process.

[0115] 18, in step S19, ultrasound diagnostic device 100A determines to simultaneously display the normal image and the mutual calculation image, and in step S20 generates composite image data in which ultrasound image I11 of the normal image data and mutual calculation image I15 of the mutual calculation image data are arranged in parallel in the horizontal direction, and in step S28 displays the composite image of the composite image data (ultrasound image I11 and mutual calculation image I15) on display unit 18. The user can easily and accurately visually recognize the difference between ultrasound image I11 (normal image) and mutual calculation image I15.

[0116] Next, an example will be described in which a mutually calculated image of an ultrasound image of ultrasound image data obtained by scanning a subject, which is pork, is displayed in parallel with a difference image using ultrasound diagnostic device 100A, where n = 4. It is assumed that setting information for generating and displaying a difference image between a normal image and a mutually calculated image is stored in advance based on operation input from the user via operation input unit 11.

[0117] As in FIG. 15, the ultrasound diagnostic device 100A generates ultrasound images I11, I12, I13, and I14 in steps S14 to S16 through the first ultrasound image display process, and in step S17, performs multiplication as a mutual operation on (the imaging signals of) the ultrasound images I11, I12, I13, and I14, and generates a mutual operation image I15 by performing a power-of-four operation process as a step-adjustment decoding process.

[0118] 19, ultrasound diagnostic device 100A determines in step S21 to generate a difference image, and generates in step S22 a difference image (difference imaging signal) between ultrasound image I11 of the normal image data and mutual calculation image I15 of the mutual calculation image data. Then, ultrasound diagnostic device 100A determines in step S23 to display the difference image, and generates, colors, and combines the normal image data of ultrasound image I11 and difference image data I51 of ultrasound image I11 and the mutual calculation image I15 to generate composite image data. Finally, in step S28, the display unit 18 displays a composite image of the composite image data (the mutual calculation image I15 and the difference image I51). The colored difference image I51 is displayed as a parametric display.

[0119] The difference image I51 is composed of pixels representing the difference in brightness between pixels at the same position in the ultrasound image I11 and the mutual operation image I15. In the figure, each pixel in the difference image I51 is colored white, light gray, dark gray, and black, corresponding to low to high difference values. However, the displayed difference image I51 is actually colored by using a coloring LUT conversion to change the hue of each pixel, for example, from black to blue to green to yellow to white, corresponding to low to high difference values. A difference image for parametric display with a changed hue allows the user to more easily grasp the extent and frequency of pixels with the same brightness difference than a difference image representing difference values only in black and white. The difference image may also be colored with other hues, or a black-and-white difference image may be displayed. The difference image I51 may also be a difference image corresponding to a region of interest (ROI) in the ultrasound image I11 input by the user via the operation input unit 11.

[0120] As described above, according to this embodiment, ultrasound diagnostic apparatus 100A includes sound ray signal generator 14A that generates sound ray signals based on received signals obtained from ultrasound probe 2 that transmits and receives ultrasound to and from a subject, imaging signal extractors 15a1-15an that perform filtering of the sound ray signals using first to n-th bandpass filters to pass through multiple (n) different bands and generate first to n-th imaging signals, and imaging signal calculator 15b that performs mutual calculation of the first to n-th imaging signals. Therefore, by mutual calculation of multiple ultrasound images with different imaging conditions (frequency bands), it is possible to visualize tissue (reflectors) with high resolution even in a subject with many scatterers in the tissue while suppressing scattered acoustic noise, thereby achieving both high resolution and tissue recognition ability.

[0121] Furthermore, the imaging signal calculation unit 15b multiplies the first to n-th imaging signals as a mutual calculation, which reduces the processing load without using complex image processing due to multiplication, and enables tissues (reflectors) to be visualized with high resolution and scattered acoustic noise to be suppressed.

[0122] Furthermore, the imaging signal calculation unit 15b performs a power root calculation of n, which corresponds to the n of the first to n-th imaging signals, on the mutually calculated first to n-th imaging signals. Therefore, the scale adjustment calculation using the power root calculation of n allows appropriate scale adjustment calculation to be performed relatively easily, and it is possible to prevent an ultrasound image in which only high brightness areas are emphasized by multiplication alone and tissue visibility is deteriorated.

[0123] Furthermore, the imaging signal calculation unit 15b performs LUT conversion processing on the mutually calculated first to n-th imaging signals. Therefore, the gradation adjustment and decoding processing by the LUT conversion processing can prevent sequential calculations and perform appropriate gradation adjustment and decoding processing, and can prevent an ultrasound image in which only high-intensity areas are emphasized by multiplication alone and tissue visibility is deteriorated.

[0124] Furthermore, the ultrasonic probe 2 has a -20 dB frequency band ratio of 100% or more. If the -20 dB frequency band ratio of the ultrasonic probe 2 is reduced, it becomes difficult to obtain a difference between high brightness areas and low brightness areas in a plurality of ultrasonic images with different imaging conditions (frequency bands). This improves the effect of tissue recognition by increasing the resolution of the mutual calculation image and suppressing scattered acoustic noise.

[0125] The ultrasound diagnostic device 100A also includes a transmitter 12 that generates a drive signal including multiple fundamental waves with different frequencies and outputs the drive signal to the ultrasound probe 2. The sound ray signal generator 14A generates a sound ray signal including harmonic components of the multiple fundamental waves, thereby further improving the resolution of the mutual calculation image.

[0126] Furthermore, the imaging signal calculation unit 15b sets brightness values of the imaging signal before the mutual calculation below a certain value to 0. This makes it possible to enhance the suppression of low-correlation signal parts (scattered components) in the mutual calculation image, and makes it easier to visually recognize high-correlation signal parts (reflected components).

[0127] Furthermore, ultrasound diagnostic device 100A includes display image synthesis unit 17a that simultaneously and in parallel displays a normal image based on normal imaging signals that have not undergone mutual calculation and a mutual calculation image based on imaging signals that have undergone mutual calculation on display unit 18. This allows the user to easily compare and visually recognize the normal image and the mutual calculation image.

[0128] Furthermore, the ultrasound diagnostic device 100A includes an image signal analysis unit 15c that generates a differential imaging signal of a differential image between a normal image based on a normal imaging signal that has not been subjected to mutual calculation and a mutual calculation image based on an imaging signal that has been subjected to mutual calculation, and an image processing unit 17A (display image synthesis unit 17a) that displays the differential image of the differential imaging signal on the display unit 18. This allows the user to visually recognize the differential image between the normal image and the mutual calculation image, and use it for diagnosis.

[0129] Furthermore, the image processing unit 17A (image analysis display value generating unit 17b) applies color to the difference image and displays the colored difference image on the display unit 18. This allows the user to visually recognize the colored difference image and use it for diagnosis.

[0130] Furthermore, the image signal analysis unit 15c calculates an index value based on the differential image. The image processing unit 17A (display image synthesis unit 17a) displays the index value based on the differential image on the display unit 18. This allows the user to visually recognize the index value of the differential image and use it for diagnosis.

[0131] (Second embodiment) A second embodiment of the present invention will be described with reference to Figures 20 and 21. Figure 20 is a block diagram showing a schematic configuration of an ultrasound diagnostic apparatus 100B according to this embodiment. Figure 21 is a flowchart showing a second ultrasound image display process.

[0132] First, the device configuration of this embodiment will be described with reference to Fig. 20. As shown in Fig. 20, an ultrasound diagnostic device 100B is used as the device configuration of this embodiment. Here, the same reference numerals are used to designate parts of ultrasound diagnostic device 100B that are similar to those of ultrasound diagnostic device 100A of the first embodiment, and their description will be omitted, with the differences being mainly described.

[0133] The ultrasonic diagnostic device 100B includes an ultrasonic diagnostic device main body 1B and an ultrasonic probe 2. The ultrasonic diagnostic device main body 1B includes an operation input unit 11, a transmitting unit 12, a receiving unit 13, a sound ray signal generating unit 14A, a signal processing unit 15B, a DSC 16, an image processing unit 17B, a display unit 18, and a control unit 19B.

[0134] The signal processing unit 15B has imaging signal extraction units 15a1, 15a2 to 15an. The DSC 16, under the control of the control unit 19B, performs envelope detection processing, logarithmic compression, etc. on the first imaging signal (normal imaging signal) to the n-th imaging signal as sound ray signals input from the imaging signal extraction units 15a1 to 15an, and performs brightness conversion by adjusting the dynamic range and gain. Then, polar coordinate conversion and display pixel interpolation are performed as necessary to generate first image data (normal image data) to n-th image data as B-mode image data for display.

[0135] The image processing unit 17B is a circuit that processes image data input from the DSC 16, and has an image calculation unit 17c as a calculation unit, an image analysis unit 17d as an analysis unit, a display image synthesis unit 17a, and an image analysis display value generation unit 17b.

[0136] The image calculation unit 17c, under the control of the control unit 19B, generates mutual calculation image data by performing multiplication as a mutual calculation on the first to n-th image data input from the DSC 16. Further, under the control of the control unit 19B, the image calculation unit 17c performs gradation adjustment decoding processing on the generated mutual calculation image data.

[0137] The image analysis unit 17d analyzes the mutual calculation image data calculated by the image calculation unit 17c under the control of the control unit 19B. This analysis includes a process of calculating the difference between the normal image data and the mutual calculation imaging data to generate differential image data of the differential image, and a process of generating an index value based on the generated differential image of the differential image data.

[0138] The display image synthesis unit 17a is a circuit that, under the control of the control unit 19B, synthesizes at least two of the following data in parallel: normal image data input from the DSC 16, mutual calculation image data input from the image calculation unit 17c, differential image data for display input from the image analysis display value generation unit 17b, and index values based on the differential image, to generate synthetic image data for display.

[0139] The image analysis display value generation unit 17b, under the control of the control unit 19B, applies color to the differential image data input from the DSC 16 to generate differential image data for display, and generates an index value based on the differential image for display from the index value based on the differential image input from the image analysis unit 17d.

[0140] The control unit 19B has a configuration similar to that of the control unit 19A of the first embodiment, and centrally controls the operations of the components of the ultrasound diagnostic apparatus 100B. The ROM of the control unit 19B stores a second ultrasound image display program for executing a second ultrasound image display process, which will be described later, instead of the first ultrasound image display program.

[0141] Next, the operation of the ultrasound diagnostic device 100B will be described with reference to Fig. 21. Specifically, the second ultrasound image display process executed by the ultrasound diagnostic device 100B will be described with reference to Fig. 21. The second ultrasound image display process is a process of generating mutually calculated image data from image data of a plurality of ultrasound images with different imaging conditions, and displaying the mutually calculated image, etc.

[0142] In the ultrasound diagnostic device 100B, the control unit 19B accepts input of various setting information for ultrasound image display from a user such as a doctor or technician via the operation input unit 11, and stores the input setting information in a RAM or a storage unit (not shown) of the control unit 19B in advance. The input setting information includes content information of a gradation adjustment process to be performed on the mutual calculation image (mutual calculation image data), information on whether to simultaneously display the mutual calculation image with the normal image, information on whether to generate a difference image between the mutual calculation image and the normal image, information on whether to display the difference image, and information on whether to generate an index value based on the difference image.

[0143] In the ultrasonic diagnostic device 100B, for example, when a user inputs an instruction to execute the second ultrasonic image display process via the operation input unit 11, the control unit 19B executes the second ultrasonic image display process in accordance with the second ultrasonic image display program stored in the ROM. Implement the theory.

[0144] As shown in Fig. 21, steps S31 to S36 are the same as steps S11 to S16 of the first ultrasonic image display processing in Fig. 12. Then, the control unit 19B causes the DSC 16 to generate the first to nth image data from the first to nth imaging signals generated in steps S34 to S36, and causes the image calculation unit 17c to perform a mutual calculation on the generated first to nth image data to generate mutual calculation image data (step S37). The mutual calculation here is assumed to be multiplication of the first to nth image data (multiplication of the brightness values of each pixel at the same position in the image data images).

[0145] Then, the control unit 19B refers to the setting information stored in the RAM or memory unit (not shown) and causes the image calculation unit 17c to perform gradation adjustment processing corresponding to the setting information on the mutual calculation image data generated in step S37 (step S38).

[0146] Step S39 is the same as step S19 in Fig. 12. When the mutual calculation image and the normal image are displayed simultaneously (step S39; YES), the control unit 19B causes the display image synthesis unit 17a to generate synthesized image data in which the normal image and the mutual image are arranged in parallel from the normal image data (first image data) generated in step S37 and the mutual calculation image data after the gradation adjustment decoding process generated in step S38 (step S40).

[0147] Step S41 is the same as step S21 in Fig. 12. When generating a difference image (step S41; YES), the control unit 19B causes the image analysis unit 17d to take the difference between the normal image data (first image data) generated in step S37 and the mutually calculated image data after the gradation adjustment restoration process generated in step S38, to generate difference image data (step S42).

[0148] Step S43 is the same as step S23 in Fig. 12. When the difference image is to be displayed (step S43; YES), the control unit 19B causes the image analysis display value generation unit 17b to generate difference image data for display by coloring the difference image data generated in step S42, and causes the display image synthesis unit 17a to generate a mutual calculation image and synthesized image data in which the mutual calculation image is arranged in parallel from the mutual calculation image data generated in step S37 and the difference image data for display (step S44).

[0149] Step S45 is the same as step S45 in Fig. 12. When displaying index values based on the differential image (step S45; YES), the control unit 19B causes the image analysis unit 17d to calculate index values based on the differential image from the differential image data generated in step S42 (step S46). Then, the control unit 19B causes the image analysis display value generation unit 17b to generate index values based on the differential image for display from the index values based on the differential image, and causes the display image synthesis unit 17a to generate synthesized image data in which the index values based on the mutual calculation image and the differential image for display are arranged, from the index values based on the mutual calculation image data generated in step S38 and the differential image for display (step S47).

[0150] After step S47 is executed, or if the index value based on the difference image is not displayed (step S45; NO), the control unit 19B displays the composite image of the composite image data generated in steps S40, S44, and S47 on the display unit 18 (step S28), and ends the second ultrasound image display process. However, in step S48, if all of steps S39, S41, S43, and S45 are NO, the control unit 19B displays the mutual calculation image of the mutual calculation image data after the gradation adjustment recovery process generated in step S38 on the display unit 18.

[0151] As described above, according to this embodiment, the imaging signal to be processed by mutual calculation etc. is image data. Therefore, similar to the first embodiment, By mutually computing multiple ultrasound images, it is possible to visualize the tissue (reflectors) with high resolution even in subjects with many scatterers within the tissue, while suppressing acoustic noise, achieving both high resolution and tissue recognition.

[0152] (Third embodiment) A third embodiment of the present invention will be described with reference to Figs. 22 to 26. Fig. 22 is a block diagram showing a schematic configuration of an ultrasound diagnostic device 100C of this embodiment. Fig. 23 is a flowchart showing a third ultrasound image display process. Fig. 24 is a diagram showing ultrasound images I61, I62, and I63 with different delay-and-sum conditions. Fig. 25 is a diagram showing watershed-divided images I71, I72, and I73 corresponding to ultrasound images I61, I62, and I63 of Fig. 24. Fig. 26 is a flowchart showing a fourth ultrasound image display process.

[0153] First, the device configuration of this embodiment will be described with reference to Fig. 22. As shown in Fig. 22, an ultrasound diagnostic device 100C is used as the device configuration of this embodiment. Here, the same reference numerals are used to designate parts of ultrasound diagnostic device 100C that are similar to those of ultrasound diagnostic device 100A of the first embodiment, and their description will be omitted, with the differences being mainly described.

[0154] The ultrasonic diagnostic device 100C includes an ultrasonic diagnostic device main body 1B and an ultrasonic probe 2. The ultrasonic diagnostic device main body 1C includes an operation input unit 11, a transmitting unit 12, a receiving unit 13, a sound ray signal generating unit 14C, a signal processing unit 15C, a DSC 16, an image processing unit 17A, a display unit 18, and a control unit 19C.

[0155] The receiving unit 13 receives electrical reception signals corresponding to first to Nth (N: a natural number equal to or greater than 2) phase adjusting and summing conditions from the ultrasonic probe 2 under the control of the control unit 19C. The first to Nth phase adjusting and summing conditions are conditions related to the phase adjusting and summing of reception signals, and include conditions such as a reception numerical aperture (reception aperture width) corresponding to the number of reception channels of the transducer 2a of the ultrasonic probe 2, a set sound velocity, and apodization. The driving signals generated by the transmitting unit 12 are driving signals corresponding to the first to Nth phase adjusting and summing conditions.

[0156] The sound ray signal generation unit 14C includes sound ray signal generation units 14b1 to 14bN and a harmonic component extraction unit 14a. The sound ray signal generation units 14b1 to 14bN each include an amplifier, an A / D conversion circuit, and a phasing and summing circuit, and generate first to N-th sound ray signals (first to N-th sound ray data) from the reception signals received by the reception unit 13 according to first to N-th phasing and summing conditions under the control of the control unit 19C. For example, when the first phasing and summing condition is a full-aperture reception numerical aperture, the sound ray signal generation unit 14b1 generates a first sound ray signal (a normal image sound ray signal for a normal image corresponding to the full-aperture reception numerical aperture) from the reception signals according to the first phasing and summing condition. Note that the sound ray signal generation unit 14b1 may be configured to generate a normal image sound ray signal according to a normal phasing and summing condition.

[0157] The harmonic component extractor 14a, under the control of the controller 19C, extracts harmonic components from the first to Nth acoustic ray signals output from the acoustic ray signal generators 14b1 to 14bN by performing a pulse inversion method.

[0158] The signal processing unit 15C has imaging signal extraction units 15a1 to 15an, an imaging signal calculation unit 15b, and an image signal analysis unit 15c. In the fourth ultrasonic image display processing described later, the imaging signal extraction unit 15a1 passes frequency components through a first band-pass filter from the 1st to Nth acoustic ray signals after harmonic component extraction input from the harmonic component extraction unit 14a to extract 1-1st to N-1st imaging signals. The 1-1st imaging signal becomes a normal imaging signal. Similarly, in the fourth ultrasonic image display processing described later, the imaging signal extraction units 15a2 to 15an extract: The 1-2th to N-2th imaging signals, . . . , the 1-nth to Nnth imaging signals are extracted, respectively.

[0159] The imaging signal calculation unit 15b, in accordance with the control of the control unit 19C, performs a mutual calculation on the 1-1 to Nn-th imaging signals for generating B-mode image data, which are generated by the imaging signal extraction units 15a1 to 15an, to generate a mutual calculation imaging signal in a fourth ultrasonic image display process described later. Note that, in a third ultrasonic image display process described later, the imaging signal calculation unit 15b can also perform a mutual calculation on the 1-1 to N-th acoustic ray signals after harmonic component extraction, which are input from the harmonic component extraction unit 14a, to generate a mutual calculation imaging signal. Furthermore, the imaging signal calculation unit 15b performs a step-down process on the generated mutual calculation imaging signal in accordance with the control of the control unit 19C.

[0160] The image signal analysis unit 15c, under the control of the control unit 19C, analyzes the mutually calculated imaging signal calculated by the imaging signal calculation unit 15b, and generates a differential imaging signal between the normal imaging signal and the mutually calculated imaging signal, and an index value based on the differential image.

[0161] The control unit 19C has a configuration similar to that of the control unit 19A of the first embodiment, and centrally controls the operations of each unit of the ultrasonic diagnostic apparatus 100C. The ROM of the control unit 19C stores, instead of the first ultrasonic image display program, a third ultrasonic image display program for executing a third ultrasonic image display process (to be described later) and a fourth ultrasonic image display program for executing a fourth ultrasonic image display process (to be described later).

[0162] Next, the operation of the ultrasonic diagnostic device 100C will be described with reference to Figures 23 to 26. First, the third ultrasonic image display process executed by the ultrasonic diagnostic device 100C will be described with reference to Figure 23. The third ultrasonic image display process is a process for generating a mutually calculated imaging signal from imaging signals of a plurality of ultrasonic images having different matching addition conditions, and displaying a mutually calculated image, etc.

[0163] In the ultrasound diagnostic device 100C, the control unit 19C accepts input of various setting information for ultrasound image display from a user such as a doctor or technician via the operation input unit 11, and stores the input setting information in a RAM or a storage unit (not shown) of the control unit 19C. The input setting information includes information on the content of gradation adjustment processing to be performed on the mutual calculation image (mutual calculation imaging signal), information on whether to simultaneously display the mutual calculation image with the normal image, information on whether to generate a difference image between the mutual calculation image and the normal image, information on whether to display the difference image, and information on whether to generate an index value based on the difference image.

[0164] In the ultrasonic diagnostic device 100C, for example, when a user inputs an instruction to execute the third ultrasonic image display process via the operation input unit 11, the control unit 19C executes the third ultrasonic image display process in accordance with the third ultrasonic image display program stored in the ROM.

[0165] As shown in Fig. 23, step S51 is similar to step S11 of the first ultrasound image display processing in Fig. 12. Then, the control unit 19C causes the receiving unit 13 to receive reflected ultrasound waves that are the ultrasound waves transmitted in step S11 and reflected and scattered by the subject, and generate a received signal (step S52).

[0166] Then, the control unit 19C causes the sound ray signal generation unit 14b1 to amplify, A / D convert, and perform phase addition on the reception signal generated in step S52 according to the first phase-delay-and-sum condition, and generate a first sound ray signal including harmonic components of the three fundamental wave components (step S53).The control unit 19C then causes the harmonic component extraction unit 14a to extract harmonic components from the first sound ray signal generated in step S53 using a pulse inversion method, and Then, the control unit 19C causes the signal processing unit 15C to generate a first acoustic ray signal from the first acoustic ray signal generated in step S54 as a first imaging signal (step S55).

[0167] In parallel with steps S53 to S55, the control unit 19C causes the sound ray signal generation unit 14b2 to amplify, A / D convert, and perform phase delay and summation on the received signal generated in step S52 according to the second phase delay and summation condition to generate a second sound ray signal including harmonic components of the three fundamental wave components (step S56).Then, the control unit 19C causes the harmonic component extraction unit 14a to extract harmonic components from the second sound ray signal generated in step S56 using the pulse inversion method, and generates a second sound ray signal from which the harmonic components have been extracted (step S57).Then, the control unit 19C causes the signal processing unit 15C to generate the second sound ray signal generated in step S57 as a second imaging signal (step S58).

[0168] Similarly, the control unit 19C causes the sound ray signal generation units 14b3 to 14b(N-1), the harmonic component extraction unit 14a, and the signal processing unit 15C to generate third to (N-1) imaging signals. In parallel with steps S53 to S55, the control unit 19C causes the sound ray signal generation unit 14bN to amplify, A / D convert, and phase-and-sum the received signal generated in step S52 according to the Nth phase-and-sum condition, to generate an Nth sound ray signal including harmonic components of the three fundamental wave components (step S59). The control unit 19C then causes the harmonic component extraction unit 14a to extract harmonic components from the Nth sound ray signal generated in step S59 using a pulse inversion method, and generate an Nth sound ray signal from which the harmonic components have been extracted (step S60). Then, the control unit 19C causes the signal processing unit 15C to generate the Nth acoustic ray signal generated in step S60 as an Nth imaging signal (step S61).

[0169] Then, control unit 19C causes imaging signal calculation unit 15b to perform mutual calculation on the first to Nth imaging signals generated in steps S55, S58, and S61 to generate mutually calculated imaging signals (step S62). The mutual calculation here is assumed to be multiplication of the first to Nth imaging signals. Steps S63 to S73 are similar to steps S18 to S28 in FIG. 12.

[0170] Here, an example of an image in the third ultrasonic image display process will be described with reference to FIGS.

[0171] 24, an ultrasound image of ultrasound image data obtained by scanning a subject with a wire target placed in a phantom using ultrasound diagnostic device 100C, where N=3, will be described. In the third ultrasound image display process, ultrasound diagnostic device 100C generates first to third imaging signals of ultrasound images I61, I62, and I63 with different delay-and-sum conditions in steps S55, S58, and S61.

[0172] Ultrasonic image I61 is an ultrasonic image based on sound ray signals obtained by delay-and-sum using the receive numerical aperture of the full aperture of the ultrasonic probe 2 as the first delay-and-sum condition. Ultrasonic image I62 is an ultrasonic image based on sound ray signals obtained by delay-and-sum using the receive numerical aperture of 2 / 3 of the full aperture as the second delay-and-sum condition, which is more restrictive than the first delay-and-sum condition. Ultrasonic image I63 is an ultrasonic image based on sound ray signals obtained by delay-and-sum using the receive numerical aperture of 1 / 3 of the full aperture as the third delay-and-sum condition, which is more restrictive than the second delay-and-sum condition. According to ultrasonic images I61, I62, and I63, reducing the receive numerical aperture changes the degree of interference between the receive channels, and the speckle pattern, which is an interference pattern, changes. Furthermore, according to the ultrasound images I61, I62, and I63, by changing the delay-and-sum conditions (receive numerical aperture), the brightness correlation of the reflected components from the wire target at the same position is high, but the granularity of the matrix portion, which is the interference area, changes mainly in the azimuth direction, and the position of the low brightness part changes, so the brightness correlation of the scattered components at the same position is low. The mutually computed image obtained by mutually computing the ultrasound images of the first embodiment shows reflectors (reflected components) with high resolution and scatterers (scattered components) are suppressed, similar to the mutually computed image obtained by mutually computing a plurality of ultrasound images with varying imaging conditions (frequency bands) in the first embodiment.

[0173] As shown in Figure 25, watershed segmented images I71, I72, and I73 are ultrasound images I61, I62, and I63, respectively, that have been subjected to watershed segmentation processing under the same conditions to depict the image brightness valleys (low brightness areas). Looking at watershed segmented images I71, I72, and I73, it can be seen that the image brightness valleys (black lines in watershed segmented images I71, I72, and I73) have changed due to limitations in the receiving numerical aperture. This demonstrates that generating a mutual operation image from ultrasound images I61, I62, and I63 obtained under different delay-and-sum conditions is effective in suppressing scattered components while retaining reflected components.

[0174] Next, a fourth ultrasonic image display process executed by the ultrasonic diagnostic device 100C will be described with reference to Fig. 26. The fourth ultrasonic image display process is a process of generating a mutually calculated imaging signal from imaging signals of a plurality of ultrasonic images having different imaging conditions and delay-and-sum conditions, and displaying a mutually calculated image, etc.

[0175] In the ultrasound diagnostic device 100C, the control unit 19C accepts input of various setting information for ultrasound image display from a user such as a doctor or technician via the operation input unit 11, and stores the input setting information in a RAM or a storage unit (not shown) of the control unit 19C. The input setting information includes information on the content of gradation adjustment processing to be performed on the mutual calculation image (mutual calculation imaging signal), information on whether to simultaneously display the mutual calculation image with the normal image, information on whether to generate a difference image between the mutual calculation image and the normal image, information on whether to display the difference image, and information on whether to generate an index value based on the difference image.

[0176] In the ultrasonic diagnostic device 100C, for example, when a user inputs an instruction to execute the fourth ultrasonic image display process via the operation input unit 11, the control unit 19C executes the fourth ultrasonic image display process in accordance with the fourth ultrasonic image display program stored in the ROM.

[0177] As shown in Fig. 26, steps S81 to S84 are the same as steps S51 to S54 of the third ultrasonic image display processing in Fig. 23. Then, the control unit 19C causes the imaging signal extraction unit 15a1 to pass the first acoustic ray signal generated in step S84 through a first band-pass filter that passes a predetermined frequency band as a first imaging condition to generate a 1-1 imaging signal (normal imaging signal) (step S85). Similarly, in parallel with step S85, the control unit 19C causes the imaging signal extraction units 15a2 to 15a(n-1) to generate 1-2 to 1-(n-1) imaging signals. Also, in parallel with step S85, the control unit 19C causes the imaging signal extraction unit 15an to pass the first acoustic ray signal generated in step S84 through an n-th band-pass filter that passes a predetermined frequency band as an n-th imaging condition to generate a 1-n imaging signal (step S86).

[0178] Similarly, in parallel with steps S83 to S86, the control unit 19C causes the sound ray signal generation units 14b2 to 14b(N-1), the harmonic component extraction unit 14a, and the imaging signal extraction units 15a1 to 15an to generate the 2-1st to 2-nth imaging signals to the (N-1)-1st to (N-1)-nth imaging signals.

[0179] Steps S87 and S88 are the same as steps S59 and S60 in Fig. 23. Then, the control unit 19C causes the imaging signal extraction unit 15a1 to pass the Nth acoustic ray signal generated in step S88 through a first band-pass filter that passes a predetermined frequency band (band) as a first imaging condition, thereby generating an N-1th imaging signal (step S89). In parallel with step S89, the control unit 19C causes the imaging signal extraction units 15a2 to 15a(n-1) to generate the (N-2)th to (N-(n-1))th imaging signals. Also, in parallel with step S89, the control unit 19C causes the imaging signal extraction unit 15an to pass the Nth acoustic ray signal generated in step S88 through an nth band-pass filter that passes a predetermined frequency band as the nth imaging condition, to generate an Nnth imaging signal (step S90).

[0180] Then, control unit 19C causes imaging signal calculation unit 15b to perform mutual calculation on the 1-1 to Nn-th imaging signals generated in steps S85 to S86 to S89 to S90 to generate mutually calculated imaging signals (step S91). The mutual calculation here is assumed to be multiplication of the 1-1 to Nn-th imaging signals. Steps S92 to S102 are similar to steps S63 to S73 in FIG. 23.

[0181] As described above, according to this embodiment, the ultrasound diagnostic apparatus 100C is equipped with sound ray signal generators 14b1 to 14bN that perform delay-and-sum under a plurality of different delay-and-sum conditions on received signals obtained from an ultrasound probe that transmits and receives ultrasound to a subject, in response to the third ultrasound image display process, to generate a plurality (N) of first to Nth sound ray signals, and an imaging signal calculator 15b that performs mutual calculation of first to Nth imaging signals based on the first to Nth sound ray signals. Therefore, by mutual calculation of a plurality of ultrasound images under different delay-and-sum conditions, it is possible to visualize the tissue (reflectors) with high resolution even in a subject with many scatterers in the tissue, while suppressing scattered acoustic noise, thereby achieving both high resolution and tissue recognition ability.

[0182] Furthermore, the ultrasound diagnostic device 100C includes imaging signal extraction units 15Aa1-15an that perform filtering on a plurality (N) of 1st to Nth acoustic ray signals to pass through a plurality (n) of different bands in response to the fourth ultrasound image display process, thereby generating 1-1st to Nnth imaging signals. Therefore, by mutual calculation of a plurality of ultrasound images with different imaging conditions (frequency bands) and delay-and-sum conditions, it is possible to visualize tissue reflectors with high resolution even in a subject with many scatterers in the tissue, while suppressing scattered acoustic noise, thereby achieving both high resolution and tissue recognition ability.

[0183] In the above description, an example has been disclosed in which a ROM is used as a computer-readable medium for the program according to the present invention, but this is not limiting. Other computer-readable media include non-volatile memory such as a flash memory and portable recording media such as a CD-ROM. Furthermore, a carrier wave is also applicable to the present invention as a medium for providing data for the program according to the present invention via a communication line.

[0184] The description of the above embodiment is an example of a suitable ultrasonic diagnostic apparatus and program according to the present invention, and is not limited thereto. For example, at least two of the above first to third embodiments may be appropriately combined. As a specific example, the second and third embodiments may be combined to form an ultrasonic diagnostic apparatus 100C in which the image processing unit 17A has an image calculation unit 17c and an image analysis unit 17d, and the control unit 19C causes the sound ray signal generation unit 14C to generate 1st to Nth imaging signals, causes the imaging signal extraction units 15a1 to 15an to generate 1-1st to Nnth imaging signals, causes the image calculation unit 17c to perform mutual calculation on the 1-1st to Nnth image data obtained via the DSC 16 to generate mutual calculation image data, and causes the image analysis unit 17d to analyze the mutual calculation image data (to generate difference image data and generate index values based on the difference images).

[0185] In the first to third embodiments, the processing in the signal processing units 15A, 15B, and 15C and the image processing units 17A and 17B may be performed in units of frames or sound rays.

[0186] In the first to third embodiments, the mutual calculation is performed by multiplying a plurality of ultrasound images (imaging signals (sound ray signals) or image data), but the present invention is not limited to this. For example, the mutual calculation of ultrasound images may be performed by a method other than multiplication, which utilizes the correlation difference in image brightness to obtain a post-calculation brightness value. Specifically, for m (m: a natural number of 2 or more) ultrasound images with different image formation conditions and delay-and-sum conditions, the variation in brightness values (L1, L2, L3, ..., Lm) of each image at each pixel coordinate position (x, y) is obtained as a variance value V, and the reciprocal of this value is multiplied by the average value LA of the brightness values, thereby obtaining a mutual calculation image (imaging signal (acoustic ray signal) or image data) of the mutual calculation brightness values that reflects the magnitude of the variation.

[0187] Furthermore, in the first to third embodiments, the ultrasonic diagnostic devices 100A to 100C are configured to generate drive signals for the pulse inversion method using the pulse inversion method in the transmitter 12, and generate sound ray signals for B-mode images for the pulse inversion method in the sound ray signal generators 14A and 14C, and are targeted for a harmonic imaging mode, but this is not limited to this.The ultrasonic diagnostic devices may be configured to target a harmonic imaging mode in which harmonics are extracted by a so-called filter method, in which a normal drive signal is generated in the transmitter 12 and sound ray signals for B-mode images are generated in the sound ray signal generators 14A and 14C without using the pulse inversion method, or a fundamental wave imaging mode without performing harmonic extraction processing.

[0188] Furthermore, the detailed configurations and operations of the components constituting the ultrasonic diagnostic devices 100A, 100B, and 100C in the first to third embodiments can be modified as appropriate without departing from the spirit of the present invention. [Explanation of symbols]

[0189] 100A, 100B, 100C Ultrasound diagnostic equipment 1A, 1B, 1C Ultrasound diagnostic device main body 11 Operation input section 12 Transmitter 121 Clock generation circuit 122 Pulse Generator Circuit 123 Time and voltage setting unit 124 Delay Circuit 13 Receiving unit 14A,14C,14b1~14bN Sound ray signal generation section 14a Harmonic component extraction section 15A, 15B, 15C Signal processing section 15a1~15an Imaging signal extraction section 15b Imaging signal calculation unit 15c Image signal analysis unit 16 DSC 17A, 17B Image processing unit 17a Display image composition section 17b Image analysis display value generation unit 17c Image calculation section 17d Image analysis department 18 Display 19A, 19B, 19C control section 2 Ultrasonic probe 21 Ultrasonic probe body 2a Oscillator 22 Cable 23 Connector

Claims

1. a sound ray signal generating unit that generates a sound ray signal based on a received signal corresponding to one frame obtained from an ultrasound probe that transmits and receives ultrasound to and from the subject; an imaging signal generating unit that generates a plurality of imaging signals by filtering the sound ray signals through a plurality of different bands; an arithmetic unit that performs mutual arithmetic on the plurality of imaging signals by multiplication.

2. a sound ray signal generating unit that generates a plurality of sound ray signals by performing delay-and-sum under a plurality of different delay-and-sum conditions on a received signal corresponding to one frame obtained from an ultrasound probe that transmits and receives ultrasound to and from a subject; a calculation unit that performs mutual calculations on a plurality of imaging signals based on the plurality of sound ray signals.

3. 3. The ultrasonic diagnostic apparatus according to claim 2, further comprising an imaging signal generating unit that generates a plurality of imaging signals by filtering the plurality of sound ray signals so as to pass through a plurality of different bands.

4. 4. The ultrasonic diagnostic apparatus according to claim 2, wherein the calculation unit multiplies the plurality of imaging signals as the mutual calculation.

5. The ultrasound diagnostic apparatus according to claim 1 , wherein the calculation unit performs a power root calculation process on the mutually calculated imaging signals according to the plurality of imaging signals.

6. The ultrasonic diagnostic apparatus according to claim 1 , wherein the calculation unit performs LUT conversion processing on the mutually calculated imaging signal.

7. 7. The ultrasonic diagnostic apparatus according to claim 1, wherein the ultrasonic probe has a -20 dB frequency band ratio of 100% or more.

8. a transmitting unit that generates a drive signal including a plurality of fundamental waves with different frequencies and outputs the drive signal to the ultrasonic probe; The ultrasonic diagnostic apparatus according to claim 1 , wherein the sound ray signal generating unit generates sound ray signals having harmonic components of the plurality of fundamental waves.

9. The ultrasonic diagnostic apparatus according to claim 1 , wherein the calculation unit sets a luminance value of the imaging signal before the mutual calculation equal to or less than a certain value to 0.

10. 10. The ultrasound diagnostic device according to claim 1, further comprising a first display control unit that simultaneously and in parallel displays on a display unit a normal image based on normal imaging signals that have not undergone the mutual operation and a mutual operation image based on imaging signals that have undergone the mutual operation.

11. an analysis unit that generates a difference image between a normal image based on the normal imaging signal that has not been subjected to the mutual operation and a mutual operation image based on the imaging signal that has been subjected to the mutual operation; The ultrasound diagnostic apparatus according to claim 1 , further comprising: a second display control unit that displays the difference image on a display unit.

12. The ultrasound diagnostic apparatus according to claim 11 , wherein the second display control unit applies color to the difference image and displays the colored difference image on the display unit.

13. the analysis unit calculates an index value based on the difference image; The second display control unit displays an index value based on the difference image on the display unit.

13. The ultrasonic diagnostic apparatus according to claim 11 or 12.

14. The ultrasonic diagnostic apparatus according to claim 1 , wherein the imaging signal is image data.

15. Computer, a sound ray signal generating unit that generates a sound ray signal based on a received signal corresponding to one frame obtained from an ultrasound probe that transmits and receives ultrasound to and from the subject; an imaging signal generating unit that generates a plurality of imaging signals by filtering the sound ray signals through a plurality of different bands; a calculation unit that performs mutual calculation on the plurality of imaging signals by multiplication; A program to function as a

16. Computer, a sound ray signal generating unit that generates a plurality of sound ray signals by performing delay-and-sum under a plurality of different delay-and-sum conditions on a received signal corresponding to one frame obtained from an ultrasound probe that transmits and receives ultrasound to and from the subject; a calculation unit that performs mutual calculation on a plurality of imaging signals based on the plurality of sound ray signals; A program to function as a

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