Ultrasonic diagnostic device and recording medium

Abstract

To provide an ultrasonic diagnostic device that allows a user to easily perform corrections on data groups.SOLUTION: An ultrasonic diagnostic device includes: selecting a contrast image 2114 in a shade dyeing time phase T1, a contrast image 211a in an early phase T2 after the shade dyeing time phase T1, and a contrast image 2212 in a late phase T3 after the early phase T2, from multiple contrast images acquired from a cross section including a target of an analyte to which a contrast agent was administered; calculating a differential value Δ1 between an average luminance of the target and an average luminance of liver parenchyma in the contrast image 2114, a differential value Δ2 between an average luminance of the target and an average luminance of the liver parenchyma in the contrast image 211a, and a differential value Δ3 between an average luminance of the target and an average luminance of the liver parenchyma in the contrast image 2212; and when all of the differential values Δ1, Δ2, Δ3 are positive (or negative), generating an image for determining whether or not the contrast agent has been discharged from the target on the basis of temporal change in the average luminance of the target.SELECTED DRAWING: Figure 13

Description

[Technical field]

[0001] The present invention relates to an ultrasonic diagnostic apparatus that selects a contrast image of a certain time phase from a plurality of contrast images, and a storage medium that stores an instruction for selecting a contrast image of a certain time phase from a plurality of contrast images. [Background technology]

[0002] 2. Description of the Related Art As an examination method using ultrasound, a contrast ultrasound examination is known in which a contrast agent is injected into a subject to create a contrast image of the subject. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 7053910 Summary of the Invention [Problem to be solved by the invention]

[0004] In contrast ultrasound examination, a technique is known for creating an image (Wash-in Parametric Image) in which the difference in time from the reference time of the contrast examination until the brightness of each point in the ultrasound image exceeds a threshold (difference in the arrival time of the contrast agent) is expressed in color in the early phase. This technique is very important for diagnosing the target because it can express the difference between the staining speed of the target (e.g., tumor) and the staining speed of the surrounding tissue in a single image in the early phase. For example, a typical liver tumor is stained earlier than the liver parenchyma, so creating an image in the early phase is extremely useful for diagnosing a typical liver tumor.

[0005] On the other hand, the diagnostic criteria (CT / MRI LI-RADS) for diagnosing hepatocellular carcinoma using contrast ultrasound also defines the evaluation of the timing (washout) at which the contrast agent flows out of the target and the brightness of the target decreases as a guideline for differentiating hepatocellular carcinoma. For example, it is known that metastatic liver cancer loses brightness from the liver parenchyma about one minute after the administration of the contrast agent, and that hepatocellular carcinoma (HCC) loses brightness from the liver parenchyma 5 to 10 minutes after the administration of the contrast agent. For this reason, it is thought that not only the arrival time of the contrast agent but also an image that shows the timing at which the brightness of the target decreases (washout parametric image) is useful.

[0006] However, in reality, when the blood flow or liver function of the tumor is poor, or when ultrasonic attenuation is large in deep areas, it may be difficult to observe the difference in brightness between the target (e.g., tumor) and the liver parenchyma. In such cases, it may not be possible to determine the timing at which the brightness of the target decreases (washout).

[0007] Therefore, there is a need for the development of an ultrasound diagnostic device that can determine the timing at which the brightness of a target decreases (washout) even when it is difficult to observe the difference between the brightness of the target (e.g., a tumor) and the brightness of the parenchyma, for example, when the blood flow or liver function of the tumor is poor, or when ultrasonic attenuation is large at deep locations. [Means for solving the problem]

[0008] A first aspect of the present invention provides an ultrasound diagnostic device including one or more processors, the one or more processors: selecting, from a plurality of contrast images acquired from a cross section including a target of a subject to which a contrast agent has been administered, a first contrast image showing a stained state of the target in a first time phase, a second contrast image for determining whether or not the contrast agent has been discharged from the target in a second time phase after the first time phase, and a third contrast image for determining whether or not the contrast agent has been discharged from the target in a third time phase after the second time phase; determining a first magnitude relationship between a feature amount of the target in the first contrast image and a feature amount of a tissue compared to the target, a second magnitude relationship between the feature amount of the target in the second contrast image and a feature amount of the tissue, and a third magnitude relationship between the feature amount of the target in the third contrast image and a feature amount of the tissue; generating an image for determining whether or not the contrast agent has been expelled from the target in the second and third time phases based on a time change in the feature amount of the target, when all of the first magnitude relationship, the second magnitude relationship, and the third magnitude relationship indicate that the feature amount of the target is greater than the feature amount of the tissue, or that the feature amount of the target is smaller than the feature amount of the tissue; The ultrasonic diagnostic device includes:

[0009] A second aspect of the present invention provides one or more non-transitory computer-readable storage media having stored thereon one or more instructions executable by one or more processors, the one or more instructions causing the one or more processors to: selecting, from a plurality of contrast images acquired from a cross section including a target of a subject to which a contrast agent has been administered, a first contrast image showing a stained state of the target in a first time phase, a second contrast image for determining whether or not the contrast agent has been discharged from the target in a second time phase after the first time phase, and a third contrast image for determining whether or not the contrast agent has been discharged from the target in a third time phase after the second time phase; determining a first magnitude relationship between a feature amount of the target in the first contrast image and a feature amount of a tissue compared to the target, a second magnitude relationship between the feature amount of the target in the second contrast image and a feature amount of the tissue, and a third magnitude relationship between the feature amount of the target in the third contrast image and a feature amount of the tissue; generating an image for determining whether or not the contrast agent has been expelled from the target in the second and third time phases based on a time change in the feature amount of the target, when all of the first magnitude relationship, the second magnitude relationship, and the third magnitude relationship indicate that the feature amount of the target is greater than the feature amount of the tissue, or that the feature amount of the target is smaller than the feature amount of the tissue; It is a storage medium that executes the above. Effect of the Invention

[0010] In the present invention, the magnitude relationship between the feature amount of the target and the feature amount of the tissue to be compared with the target is specified for each time phase, and it is determined whether or not all of the specified magnitude relationships indicate that the feature amount of the target is larger (or smaller) than the feature amount of the tissue. Therefore, even if it is difficult to observe the difference between the brightness of the target and the brightness of the tissue to be compared, it is possible to determine the timing at which the contrast agent is discharged from the target. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram showing a state in which a subject is being scanned by an ultrasonic diagnostic apparatus 1 according to an embodiment of the present invention. [Diagram 2] FIG. 1 is a block diagram of an ultrasonic diagnostic device 1. [Diagram 3] FIG. 2 is an explanatory diagram of a timeline in which contrast images are acquired. [Figure 4] FIG. 4 is an explanatory diagram of data acquired according to the timeline shown in FIG. [Diagram 5] FIG. [Figure 6]FIG. 13 is an explanatory diagram of an initial screen for selecting a contrast image. [Figure 7] FIG. 2 shows the display unit after an image group 21 has been selected. [Figure 8] FIG. 13 is an explanatory diagram of a method for adding a region of interest. [Figure 9] FIG. 13 is a diagram showing a state in which regions of interest 51 and 52 are added to tissues to be compared with a target. [Figure 10] FIG. 13 is an explanatory diagram of a method for selecting a late phase contrast image. [Figure 11] FIG. 13 is an explanatory diagram of a method for adding a region of interest. [Figure 12] 12 is a diagram showing data groups 61 and 62 shown in FIG. 9 and data groups 63 and 64 shown in FIG. 11 arranged in chronological order. [Figure 13] FIG. 11 is an explanatory diagram of a method for calculating a difference value. [Figure 14] FIG. 11 is an explanatory diagram of a flowchart for creating a WO image in step ST5. [Figure 15] FIG. 2 shows a contrast image 200 displayed on a display unit. [Figure 16] FIG. 2 is an explanatory diagram of a region of interest 45. [Figure 17] 10 is an explanatory diagram of a procedure for determining a color to be assigned to pixel P1 in a region of interest 45. FIG. [Figure 18] FIG. 2 is an explanatory diagram of a color map 81. [Figure 19] 1 shows three regions 82, 83, and 84 of a color map 81. [Figure 20] FIG. 13 is an explanatory diagram when a color is determined by a difference value ΔE=B22−B221 and a difference value ΔL=B32−B331. [Figure 21] 13 is an explanatory diagram for determining the color to be assigned to pixel P2 in the region of interest 45. FIG. [Figure 22] FIG. 13 is an explanatory diagram when a color is determined by a difference value ΔE=B22−B222 and a difference value ΔL=B32−B332. [Figure 23] FIG. 1 is a schematic diagram showing a WO image. [Figure 24]FIG. 2 is an explanatory diagram of step ST1. [Diagram 25] FIG. 11 is an explanatory diagram of a method for calculating a difference value. [Figure 26] FIG. 2 shows a region of interest 45 added in a contrast image 200. [Figure 27] FIG. 11 is an explanatory diagram of a method for determining a color to be assigned. [Figure 28] FIG. 11 is an explanatory diagram for determining a color to be assigned to pixel Q1 based on two difference values ​​ΔE (=B13-B23) and ΔL (=B13-B33). [Figure 29] FIG. 13 is an explanatory diagram of colors assigned to pixels Q2 and Q3. [Diagram 30] FIG. 1 is a schematic diagram showing a WO image. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, a mode for carrying out the invention will be described, however, the present invention is not limited to the following mode.

[0013] FIG. 1 is a diagram showing a state in which a subject is scanned by an ultrasonic diagnostic apparatus 1 according to one embodiment of the present invention, and FIG.

[0014] The ultrasound diagnostic device 1 includes an ultrasound probe 2, a transmit beamformer 3, a transmitter 4, a receiver 5, a receive beamformer 6, a processor 7, a display unit 8, a memory 9, and a user interface 10.

[0015] The ultrasonic probe 2 has a plurality of transducer elements 2a arranged in an array. The transmit beamformer 3 and the transmitter 4 drive the plurality of transducer elements 2a arranged in the ultrasonic probe 2, and ultrasonic waves are transmitted from the transducer elements 2a. The ultrasonic waves transmitted from the transducer elements 2a are reflected in the subject 57 (see FIG. 1), and the reflected echoes are received by the transducer elements 2a. The transducer elements 2a convert the received echoes into electrical signals, and output the electrical signals as echo signals to the receiver 5. The receiver 5 performs a predetermined process on the echo signals, and outputs them to the receive beamformer 6. The receive beamformer 6 performs receive beamforming on the signals received from the receiver 5, and outputs echo data.

[0016] The receive beamformer 6 may be a hardware beamformer or a software beamformer. If the receive beamformer 6 is a software beamformer, the receive beamformer 6 may comprise one or more processors including one or more of: i) a graphics processing unit (GPU); ii) a microprocessor; iii) a central processing unit (CPU); iv) a digital signal processor (DSP); v) other types of processors capable of performing logical operations. The processors constituting the receive beamformer 6 may be separate from the processor 7 or may be comprised in the processor 7.

[0017] The ultrasound probe 2 may include electrical circuitry for performing all or part of the transmit beamforming and / or receive beamforming. For example, the transmit beamformer 3, the transmitter 4, the receiver 5, and all or part of the receive beamformer 6 may be provided within the ultrasound probe 2.

[0018] The processor 7 controls the transmit beamformer 3, the transmitter 4, the receiver 5, and the receive beamformer 6. The processor 7 is also in electronic communication with the ultrasound probe 2. The processor 7 controls which of the transducer elements 2a are active and the shape of the ultrasound beam transmitted from the ultrasound probe 2. The processor 7 is also in electronic communication with the display 8. The processor 7 can process the echo data to generate an ultrasound image. The term "electronic communication" can be defined to include both wired and wireless communication. The processor 7 can include a central processing unit (CPU) according to one embodiment. According to other embodiments, the processor 7 can include other electronic components capable of performing processing functions, such as a digital signal processor, a field programmable gate array (FPGA), a graphics processing unit (GPU), or other types of processors. According to other embodiments, the processor 7 can include multiple electronic components capable of performing processing functions. For example, the processor 7 can include two or more electronic components selected from a list of electronic components including a central processing unit, a digital signal processor, a field programmable gate array, and a graphics processing unit.

[0019] The processor 7 may also include a complex demodulator (not shown) for demodulating the RF data. In alternative embodiments, the demodulation may be performed earlier in the processing chain.

[0020] The processor 7 can also generate various ultrasound images (e.g., B-mode images, color Doppler images, M-mode images, color M-mode images, spectral Doppler images, elastography images, TVI images, strain images, strain velocity images, etc.) based on data obtained by processing by the receive beamformer 6. One or more modules can also generate these ultrasound images.

[0021] The image beams and / or image frames may be stored and timing information recorded indicating when the data was acquired in memory. The modules may include, for example, a scan conversion module that performs a scan conversion operation to convert the image frames from coordinate beam space to display space coordinates. A video processor module may be provided that reads the image frames from the memory and displays the image frames in real time while a procedure is being performed on the subject. The video processor module may store the image frames in an image memory, and the ultrasound images are read from the image memory and displayed on a display 8.

[0022] As used herein, the term "image" may refer broadly to both a visible image and data representing a visible image, and the term "data" may include raw data, which is ultrasound data before a scan conversion operation, and image data, which is data after a scan conversion operation.

[0023] The above-mentioned processing tasks handled by the processor 7 may be executed by a plurality of processors.

[0024] Furthermore, when the receive beamformer 6 is a software beamformer, the processing executed by the beamformer may be executed by a single processor or may be executed by multiple processors.

[0025] The display unit 8 is, for example, an LED (Light Emitting Diode) display, an LCD (Liquid Crystal Display), or an organic EL (Electro-Luminescence) display. The display unit 8 may be composed of one display, or may include two or more displays. The display unit 8 may also include a touch panel.

[0026] The memory 9 is any known data storage medium. In one example, the ultrasonic diagnostic apparatus includes a non-transient storage medium and a transient storage medium as the memory. The ultrasonic diagnostic apparatus may also include a plurality of memories. The non-transient storage medium is, for example, a non-volatile storage medium such as a hard disk drive (HDD) or a read only memory (ROM). The non-transient storage medium may include a portable storage medium such as a compact disk (CD) or a digital versatile disk (DVD). The program executed by the processor 7 is stored in the non-transient storage medium. The transient storage medium is a volatile storage medium such as a random access memory (RAM).

[0027] The memory 9 stores one or more instructions executable by the processor 7. The one or more instructions cause the processor 7 to perform certain operations.

[0028] The processor 7 may be configured to be connected to an external storage device via a wired or wireless connection. In this case, the instructions to be executed by the processor 7 may be stored in both the memory 9 and the external storage device in a distributed manner.

[0029] The user interface 10 can accept input from an operator 56. For example, the user interface 10 accepts input of instructions and information from the operator 56. The user interface 10 includes a touch panel and an operation panel. The operation panel includes a keyboard, hard keys, a trackball, a rotary control, and the like. In addition, the touch panel can display soft keys, buttons, and the like. The ultrasonic diagnostic apparatus 1 is configured as described above.

[0030] Next, a description will be given of the operation of the ultrasonic diagnostic device 1 of this embodiment. In this embodiment, an example will be described in which, as the operation of the ultrasonic diagnostic device 1, data of a contrast image of a subject is acquired, and an image showing the timing at which a contrast agent is discharged from a target is created based on the acquired data of the contrast image.

[0031] First, a method for acquiring contrast image data will be described. Specifically, contrast image data is acquired as follows.

[0032] FIG. 3 is an explanatory diagram of a timeline in which contrast images are acquired. The operator 56 injects a contrast agent into the subject 57 and acquires a contrast image. The contrast agent may be one containing microbubbles as an active ingredient. The operator 56 operates the probe 2 and starts acquiring a contrast image of the examination site from time t11 (the time when the contrast agent is injected or a time close to the time when the contrast agent is injected).

[0033] The processor 7 controls the ultrasonic probe 2 to transmit ultrasonic waves to the subject 57. The ultrasonic probe 2 receives ultrasonic waves (echoes) reflected by the contrast agent. The processor 7 executes a predetermined process on the echo signals to generate data indicating the signal intensity of the ultrasonic waves reflected by the contrast agent. This data indicating the signal intensity of the ultrasonic waves reflected by the contrast agent can be obtained as contrast image data.

[0034] The operator 56 intermittently acquires contrast image data over a predetermined period of time from time t11. The operator 56 intermittently acquires contrast image data over a period between time points t11 and tn2, for example. The length of time between time points t11 and tn2 may be, for example, about 15 minutes.

[0035] Note that the operator 56 does not continuously perform ultrasonic scanning and image recording between time points t11 and tn2, but collects data at required timing. In this embodiment, data of the subject 57 is continuously acquired during period SC1 (time points t11 to t12), and thereafter, data acquisition SC2 to SCn for several seconds is executed every time a certain time has elapsed. In this embodiment, the subject 57 is scanned according to the timeline shown in FIG.

[0036] FIG. 4 is an explanatory diagram of data acquired according to the timeline shown in FIG. First, the operator 56 administers a contrast agent and performs continuous scanning during a period SC1 (times t11 to t12) to acquire data of an image group 21 including a plurality of ultrasound images. The time length from time t11 to t12 is represented as "TS1". In this embodiment, the time length TS1 is 60 seconds, but the time length TS1 may be shorter or longer than 60 seconds. During the time periods t11 to t12, the processor 7 controls the ultrasound probe 2 to transmit ultrasound to the subject 57. The ultrasound probe 2 receives ultrasound (echo) reflected by the contrast agent. The processor 7 executes a predetermined process on the echo signal to create an ultrasound image showing the signal intensity of the ultrasound reflected by the contrast agent. The ultrasound image is, for example, an image acquired from a cross section of the liver of the subject 57. The processor 7 stores the acquired data of the image group 21 in the memory 9. In this embodiment, two types of ultrasound images are created as ultrasound images. One is a contrast image in which a nonlinear signal included in an echo signal reflected by a contrast agent is emphasized, and the other is a B-mode image. Thus, the image group 21 includes a contrast image set 211 including a plurality of contrast images arranged in time series, and a B-mode image set 212 including a plurality of B-mode images arranged in time series.

[0037] After acquiring data from time t11 to t12, the operator 56 stops acquiring data and waits until time t21 comes after the contrast agent is injected to start acquiring the next data. Then, the operator 56 acquires data during a period SC2 (time t21 to t22). The length of the period SC2 is, for example, 5 seconds. The processor 7 executes a predetermined process on the echo signals to create an image group 22. The image group 22 includes a contrast image set 221 including a plurality of contrast images arranged in time series, and a B-mode image set 222 including a plurality of B-mode images arranged in time series. The data of the image group 22 is stored in the memory 9.

[0038] After acquiring data from time t21 to t22, the operator 56 stops acquiring data and waits until time t31 comes after the contrast agent is injected to start acquiring the next data. The operator 56 then acquires data between time t31 and t32 (time length TS3). The time length TS3 is, for example, 5 seconds. The processor 7 executes a predetermined process on the echo signals to create an image group 23. The image group 23 includes a contrast image set 231 including a plurality of contrast images arranged in chronological order, and a B-mode image set 232 including a plurality of B-mode images arranged in chronological order. The data of the image group 23 is stored in the memory 9. Similarly, the step of acquiring data after waiting a certain period of time is repeatedly executed.

[0039] Finally, the operator 56 acquires data between the time points tn1 and tn2 (time length TSn). The processor 7 executes a predetermined process on the echo signals to create an image group 2n. The image group 2n includes a contrast image set 2n1 including a plurality of contrast images arranged in time series, and a B-mode image set 2n2 including a plurality of B-mode images arranged in time series. The data of the image group 2n is stored in the memory 9. In this manner, examination data for the subject 57 is acquired. Data obtained by scanning the subject 57 is stored in the memory 9 .

[0040] Next, the operator 56 creates an image (hereinafter referred to as a "WO image") for determining whether the contrast agent has been washed out from the target in the early phase and the late phase based on the data acquired from the subject 57. A method for creating a WO image will be described below with reference to the flowchart of FIG.

[0041] In step ST1, a contrast image of a time phase required for creating a WO image is selected from a plurality of contrast images acquired in an examination of a subject. In this embodiment, the following three time phases are considered as time phases required for creating a WO image.

[0042] (1) A time phase that represents a state in which a target (e.g., a tumor) is stained with a contrast agent (hereinafter referred to as a "staining phase"). (2) early phase, and (3) Late phase The user selects a contrast-enhanced image of the contrast-enhanced phase, a contrast-enhanced image of the early phase, and a contrast-enhanced image of the late phase, and calculates the average brightness of the target and the average brightness of the liver parenchyma for each phase based on the selected contrast-enhanced images.

[0043] A method for selecting a contrast-enhanced image in the enhancement phase, an early phase, and a late phase, and a method for calculating the average brightness of the target and the average brightness of the liver parenchyma will be described below.

[0044] First, the user displays an initial screen for selecting a contrast image. FIG. 6 is an explanatory diagram of an initial screen for selecting a contrast image. A thumbnail area 20 is displayed on the display unit 8. In the thumbnail area 20, n thumbnails 121 to 12n are displayed. The n thumbnails 121 to 12n are thumbnails corresponding to n image groups 21 to 2n acquired by scanning the subject 57. In Fig. 6, thumbnails 121, 122, 123, and 12n of four image groups 21, 22, 23, and 2n are displayed as representatives of the image groups 21 to 2n.

[0045] Here, first, a method for selecting a contrast image in a contrast phase from a contrast image in a contrast phase, an early phase, and a contrast image in a late phase will be described.

[0046] The contrast-enhanced phase is a phase that represents a state in which a target (e.g., a tumor) is stained with a contrast agent, and is a phase that appears within about one minute after the administration of the contrast agent. Meanwhile, in this embodiment, among the image groups 21 to 2n acquired by an examination of a subject, the image group 21 acquired first represents images acquired within about one minute after the administration of the contrast agent. Therefore, the contrast images in the contrast-enhanced phase are considered to be included in the image group 21. Therefore, the user selects the image group 21 from the thumbnail area 20.

[0047] FIG. 7 shows the display after an image group 21 has been selected. The user operates the user interface 10 to input a command to select the image group 21. When the user interface 10 accepts the user's input to select the image group 21, the processor selects the image group 21. Note that in FIG. 7, for reference, a schematic diagram of images included in the image group 21 is shown on the display unit 8. The image group 21 includes a contrast image set 211 and a B-mode image set 212. The contrast image set 211 includes contrast images 2111 to 211a, and the B-mode image set 212 includes B-mode images 2121 to 212a.

[0048] When the user selects an image group 21, images of the selected image group 21 are played in the image display area 40. Contrast images 2111-211a of the contrast image set 211 are played in the upper half of the image display area 40, and B-mode images 2121-212a of the B-mode image set 212 are played in the lower half. Therefore, the user can check the images acquired between time points t11 and t12 (see FIG. 4) as a moving image.

[0049] While referring to the moving image of contrast image set 211 (and B-mode image set 212), the user selects a contrast image of a time phase in which a target (e.g., a tumor) is sufficiently stained with a contrast agent from contrast images 2111-211a of contrast image set 211. For example, when the user determines that contrast image 2114 is appropriate from contrast images 2111-211a as a contrast image of a time phase in which a target (e.g., a tumor) is sufficiently stained with a contrast agent, the user operates user interface 10 to input a command to select contrast image 2114 from contrast images 2111-211a. When user interface 10 accepts a user input to select contrast image 2114, the processor selects contrast image 2114 as an image of the stained time phase.

[0050] After selecting contrast image 2114 of the contrast-enhanced phase, the user selects a contrast image of the early phase. The contrast image of the early phase is a contrast image selected to determine whether the contrast agent has been discharged from the target in the early phase. The early phase is a time phase, for example, about one minute after the contrast agent is administered. Since contrast images 2111-211a are images acquired within about one minute after the contrast agent is administered, the user can find the contrast image of the early phase from contrast images 2111-211a. For example, when the user determines that contrast image 211a is appropriate as the contrast image of the early phase from contrast images 2111-211a, the user operates user interface 10 to input a command to select contrast image 211a as the contrast image of the early phase. When the user interface 10 receives a user input selecting the contrast image 211a as the early phase contrast image, the processor selects the contrast image 211a as the early phase contrast image.

[0051] In this manner, the user can select the contrast image 2114 of the enhancement phase and the contrast image 211a of the early phase from the image group 21.

[0052] Next, the user adds a region of interest on the contrast images 2111-211a by operating the user interface 10. Fig. 8 is an explanatory diagram of a method for adding a region of interest.

[0053] The user assigns a region of interest to a target (e.g., a tumor, a lesion) of an examination site while referring to the image set 211 (and 212) displayed in the image display area 40. Specifically, the user confirms the location of the target while referring to the image sets 211 and 212, and inputs a command to assign a region of interest to the target location in the image sets 211 and 212. When the user interface 10 accepts the user's input to assign a region of interest, the processor 7 displays figures representing the regions of interest 41 and 42 on the image sets 211 and 212. In FIG. 8, the regions of interest 41 and 42 are represented by circular figures. The position of the region of interest 42 in the image set 212 (B-mode image) corresponds to the position of the region of interest 41 in the image set 211 (contrast image). The user can move the regions of interest 41 and 42 simultaneously by operating the user interface 10.

[0054] When the region of interest 41 is assigned, the processor 7 calculates a feature amount in the region of interest 41 for the contrast images 2111-211a of the image set 211. The feature amount in the region of interest 41 can be calculated, for example, as a value representing brightness information in the region of interest 41. As an example, the feature amount in the region of interest 41 can be calculated as an average value (average brightness) or standard deviation of the brightness of a plurality of pixels included in the region of interest 41. For convenience of explanation, it is assumed below that the feature amount of the region of interest is the average brightness. In this manner, the feature amount of the region of interest 41 can be calculated for each of the contrast images 2111-211a of the image set 211.

[0055] When the feature amount (average brightness) of the region of interest is calculated, the processor displays a data group 61 representing the time change of the average brightness of the region of interest 41 calculated for the contrast-enhanced images 2111-211a in the TIC region 60. The horizontal axis of the data group 61 indicates time, and the vertical axis indicates the average brightness of the region of interest. In FIG. 8, each data included in the data group 61 is shown as a black square. Note that in FIG. 8, in order to make the data group 61 visually easier to see, the total number of data included in the data group 61 is shown to be less than the total number of actual data. Each data of the data group 61 represents the average brightness of the region of interest 41 in the contrast-enhanced images 2111-211a of the image set 211. For example, data D11 represents the average brightness B11 of the target of the region of interest 41 in the contrast-enhanced image 2114 in the contrast phase T1, and data D21 represents the average brightness B21 of the target of the region of interest 41 in the contrast-enhanced image 211a in the early phase T2.

[0056] The user also assigns a region of interest to the tissue to be compared with the target. FIG. 9 is a diagram showing a state in which the regions of interest 51 and 52 are assigned to the tissue to be compared with the target. In this embodiment, the tissue to be compared with the target is the liver parenchyma, and an example in which the regions of interest 51 (and 52) are assigned to the liver parenchyma is considered, but it is also possible to assign a region of interest to a tissue other than the liver parenchyma. After the regions of interest 51 and 52 are assigned, the average brightness of the region of interest 51 is calculated, and a data group 62 representing the time change in the average brightness of the region of interest 51 is displayed. In FIG. 9, the data group 62 of the tissue (liver parenchyma) to be compared with the target is indicated by a white circle. Each data of the data group 62 represents the average brightness of the region of interest 51 in the contrast images 2111 to 211a of the image set 211. For example, data D12 represents the average brightness B12 of the liver parenchyma of region of interest 51 in contrast-enhanced image 2114 in contrast phase T1, and data D22 represents the average brightness B22 of the liver parenchyma of region of interest 51 in contrast-enhanced image 211a in early phase T2.

[0057] In the manner described above, data D11 and D12 of the enhancement phase T1 and data D21 and D22 of the early phase T2 can be obtained.

[0058] Finally, the user selects the late phase contrast image. FIG. 10 is an explanatory diagram of a method for selecting a late phase contrast image. The contrast image of the late phase is a contrast image selected to determine whether the contrast agent has been discharged from the target in the late phase. The contrast image of the late phase generally appears between 5 and 10 minutes after the administration of the contrast agent. Therefore, the user selects the image group acquired between 5 and 10 minutes after the administration of the contrast agent from among the image groups 21 to 2n. Here, it is assumed that the user selects the image group 22 acquired 5 minutes after the administration of the contrast agent. The user operates the user interface 10 to input a command to select the image group 22 including the contrast image of the late phase from the image groups 21 to 2n. When the user interface 10 accepts the user's input to select the image group 22 from the multiple image groups 21 to 2n, the processor selects the image group 22. Note that in FIG. 10, for reference, a schematic diagram of the images included in the image group 22 is shown above the display unit 8. The image group 22 includes a contrast image set 221 and a B-mode image set 222. The contrast image set 221 includes contrast images 2211 to 221b, and the B-mode image set 222 includes B-mode images 2221 to 222b.

[0059] When the user selects an image group 22, images of the selected image group 22 are displayed in the image display area 40. Contrast images 2211-221b of the contrast image set 221 are displayed in the upper half of the image display area 40, and B-mode images 2221-222b of the B-mode image set 222 are displayed in the lower half. Therefore, the user can check the images acquired between time points t21 and t22 (see FIG. 4) as a moving image.

[0060] The user selects a late phase contrast image from contrast images 2211-221b of contrast image set 221 while referring to the moving image of contrast image set 221 (and B-mode image set 222). For example, if the user determines that contrast image 2212 is appropriate as a late phase contrast image from contrast images 2211-221b, the user operates user interface 10 to input a command to select contrast image 2212 from contrast images 2211-221b. When user interface 10 accepts the user's input to select contrast image 2212, the processor selects contrast image 2212 as a late phase contrast image.

[0061] Next, the user adds a region of interest on the contrast images 2211-221b by operating the user interface 10. Fig. 11 is an explanatory diagram of a method for adding a region of interest.

[0062] The user assigns a region of interest to a target (e.g., a tumor, a lesion) of an examination site while referring to the image set 221 (and 222) displayed in the image display area 40. Specifically, the user confirms the location of the target while referring to the image sets 221 and 222, and inputs a command to assign a region of interest to the target location in the image sets 221 and 222. When the user interface 10 accepts the user's input to assign a region of interest, the processor 7 displays figures representing the regions of interest 43 and 44 on the image sets 221 and 222. In FIG. 11, the regions of interest 43 and 44 are represented by circular figures. The position of the region of interest 44 in the image set 222 (B-mode image) corresponds to the position of the region of interest 43 in the image set 221 (contrast image). The user can move the regions of interest 43 and 44 simultaneously by operating the user interface 10.

[0063] Once the region of interest 43 has been assigned, the processor 7 calculates a feature amount in the region of interest 43 for the contrast images 2211-221b of the image set 221. The feature amount in the region of interest 43 can be calculated, for example, as a value representing luminance information in the region of interest 43. Here, it is assumed that the feature amount in the region of interest 43 is the average value (average luminance) of the luminance of a plurality of pixels included in the region of interest 43. Therefore, the average luminance of the region of interest 43 can be calculated for each of the contrast images 2211-221b of the image set 221.

[0064] When the average brightness of the region of interest 43 is calculated, the processor displays the average brightness of the region of interest 43 calculated for each of the contrast-enhanced images 2211-221b of the image set 221, as shown in the TIC region 60 of FIG. 11. The TIC region 60 shows a data group 63 representing the time change of the average brightness of the region of interest 43 calculated for the contrast-enhanced images 2211-221b. In FIG. 11, each data included in the data group 63 is shown as a black square. Note that in FIG. 11, in order to make the data group 63 visually easier to see, the total number of data included in the data group 63 is shown to be less than the total number of actual data. Each data of the data group 63 represents a feature amount of the region of interest 43 in the contrast-enhanced images 2211-221b of the image set 221. For example, data D31 represents the average brightness B31 of the target of the region of interest 43 in the contrast-enhanced image 2212 of the late phase T3.

[0065] The user also assigns a region of interest to the tissue to be compared with the target. FIG. 11 is a diagram showing a state in which the regions of interest 53 and 54 are assigned to the tissue to be compared with the target. In this embodiment, the tissue to be compared with the target is the liver parenchyma, and an example in which the regions of interest 53 (and 54) are assigned to the liver parenchyma will be considered. After the regions of interest 53 and 54 are assigned, the feature amount of the region of interest 53 is calculated, and a data group 64 representing the time change in the average brightness of the region of interest 53 is displayed. In FIG. 11, the data group 64 of the tissue (liver parenchyma) to be compared with the target is indicated by a white circle. Each data of the data group 64 represents the feature amount of the region of interest 53 in the contrast-enhanced images 2211 to 221d of the image set 221. For example, data D32 represents the average brightness B32 of the liver parenchyma of the region of interest 53 in the contrast-enhanced image 2212 of the late phase T3.

[0066] As described above, data D31 and D32 for the late phase T3 can be obtained. Therefore, it is possible to obtain brightness information for the three phases (enhanced phase, early phase, and late phase) required for creating a WO image.

[0067] FIG. 12 is a diagram showing data groups 61 and 62 shown in FIG. 9 and data groups 63 and 64 shown in FIG. 11 arranged in chronological order.

[0068] Data groups 61 and 62 represent data groups acquired during data acquisition period SC1 (see FIG. 4), and data groups 63 and 64 represent data groups acquired during data acquisition period SC2 (see FIG. 4). Since no data is acquired between data acquisition periods SC1 and SC2, no data groups exist.

[0069] 12 shows time-intensity curves 71 and 72 in addition to the data groups 61 to 64. The time-intensity curve 71 is a curve obtained by connecting the target data group 61 and the data group 63 in the time axis direction, and the time-intensity curve 72 is a curve obtained by connecting the liver parenchyma data group 62 and the data group 64 in the time axis direction.

[0070] From FIG. 12, differences in the average brightness of the target and the average brightness of the liver parenchyma can be recognized for the contrast phase T1, the early phase T2, and the late phase T3.

[0071] Once the average brightness of the target and the average brightness of the liver parenchyma in the contrast-enhanced phase T1, early phase T2, and late phase T3 have been obtained, the process proceeds to step ST2 (see FIG. 5).

[0072] In step ST2, the processor determines the magnitude relationship between the average brightness of the target and the average brightness of the liver parenchyma for each of the time phases T1, T2, and T3. In this embodiment, a case will be described in which a difference value between the average brightness of the target and the average brightness of the liver parenchyma is calculated to determine the magnitude relationship between the average brightness of the target and the average brightness of the liver parenchyma, but a value other than the difference value may be calculated as long as the magnitude relationship can be determined.

[0073] FIG. 13 is an explanatory diagram of a method for calculating the difference value. The processor calculates a difference value Δ1 between the average brightness B11 of the target region of interest 41 in the contrast image 2114 at the contrast enhancement phase T1 (i.e., the average brightness B11 represented by the data D11) and the average brightness B12 of the liver parenchyma region of interest 51 (i.e., the average brightness B12 represented by the data D12). When calculating the difference value Δ1, the difference value Δ1 (=B12-B11) may be calculated by subtracting the average brightness B11 of the target region of interest 41 from the average brightness B12 of the liver parenchyma region of interest 51, or the difference value Δ1 (=B11-B12) may be calculated by subtracting the average brightness B12 of the liver parenchyma region of interest 51 from the average brightness B11 of the target region of interest 41. In this embodiment, the difference value Δ1 is calculated by subtracting the average brightness of the target region of interest 41 from the average brightness of the liver parenchyma region of interest 51. Therefore, the processor calculates a difference value Δ1 (=B12−B11) by subtracting the average brightness B11 of the target region of interest 41 from the average brightness B12 of the region of interest 51 of the liver parenchyma.

[0074] The processor also calculates a difference value Δ2 between the average brightness B21 of the target region of interest 41 in the contrast image 211a of the early phase T2 (i.e., the average brightness B21 represented by the data D21) and the average brightness B22 of the region of interest 51 of the liver parenchyma (i.e., the average brightness B22 represented by the data D22). When calculating the difference value Δ2, the difference value Δ2 (=B22-B21) may be calculated by subtracting the average brightness B21 of the target region of interest 41 from the average brightness B22 of the region of interest 51 of the liver parenchyma, or the difference value Δ2 (=B21-B22) may be calculated by subtracting the average brightness B22 of the region of interest 51 of the liver parenchyma from the average brightness B21 of the target region of interest 41. In this embodiment, similar to the difference value Δ1, the difference value Δ2 is calculated by subtracting the average brightness of the target region of interest 41 from the average brightness of the region of interest 51 of the liver parenchyma. Therefore, the processor calculates a difference value Δ2 (=B22−B21) by subtracting the average brightness B21 of the target region of interest 41 from the average brightness B22 of the region of interest 51 of the liver parenchyma.

[0075] Furthermore, the processor calculates a difference value Δ3 between the average brightness B31 of the target region of interest 41 in the contrast image 2212 of the late phase T3 (i.e., the average brightness B31 represented by the data D31) and the average brightness B32 of the liver parenchyma region of interest 51 (i.e., the average brightness B32 represented by the data D32). When calculating the difference value Δ3, the difference value Δ3 (=B32-B31) may be calculated by subtracting the average brightness B31 of the target region of interest 41 from the average brightness B32 of the liver parenchyma region of interest 51, or the difference value Δ3 (=B31-B32) may be calculated by subtracting the average brightness B32 of the liver parenchyma region of interest 51 from the average brightness B31 of the target region of interest 41. In this embodiment, similar to the difference value Δ1, the difference value Δ3 is calculated by subtracting the average brightness of the target region of interest 41 from the average brightness of the liver parenchyma region of interest 51. Therefore, the processor calculates a difference value Δ3 (=B32−B31) by subtracting the average brightness B31 of the target region of interest 41 from the average brightness B32 of the region of interest 51 of the liver parenchyma. After calculating these difference values ​​Δ1, Δ2, and Δ3, the process proceeds to step ST3.

[0076] In step ST3, the processor determines whether all of the difference values Δ1, Δ2, and Δ3 are positive (or negative).

[0077] In the shadowing phase T1, the average luminance B12 of the liver parenchyma is smaller than the average luminance B11 of the target (B12 < B11). Therefore, the difference value Δ1 < 0.

[0078] In the early phase T2, the average luminance B22 of the liver parenchyma is smaller than the average luminance B21 of the target (B22 < B21). Therefore, the difference value Δ2 < 0.

[0079] On the other hand, in the late phase T3, the average luminance B32 of the liver parenchyma is larger than the average luminance B31 of the target (B32 > B31). Therefore, the difference value Δ3 > 0.

[0080] For this reason, the difference values Δ1 and Δ2 are negative, but the difference value Δ3 is positive. Therefore, it is determined that both positive and negative difference values are included in the difference values Δ1, Δ2, and Δ3. When both positive and negative difference values are included in the difference values Δ1, Δ2, and Δ3, in the early phase, the luminance of the target is larger than the luminance of the liver parenchyma, but in the late phase, the luminance of the target is smaller than the luminance of the liver parenchyma. Therefore, since the luminance of the target is considered to vary greatly with respect to the luminance of the liver parenchyma, it represents a case with good shadowing of the target. In the case of a case with good shadowing of the target, it is considered that useful information for determining whether the contrast agent has been discharged from the target can be obtained by using both the data of the liver parenchyma and the data of the target. Therefore, when both positive and negative difference values are included in the difference values Δ1, Δ2, and Δ3, the process proceeds to step ST4, and the processor determines to create a WO image using the data of the liver parenchyma and the data of the target. Then, the process proceeds to step ST5.

[0081] FIG. 14 is an explanatory diagram of a flowchart when creating a WO image in step ST5. In step ST51, the user specifies a region within the body of the subject where it is desired to determine whether or not the contrast agent has been discharged from the target, and assigns a region of interest to the specified region.

[0082] 15 and 16 are diagrams for explaining a method of adding a region of interest to a portion where it is desired to determine whether or not the contrast agent has been expelled from the target.

[0083] A user operates user interface 10 to input a command to display contrast image 200. When user interface 10 accepts a user's input to display contrast image 200, contrast image 200 is displayed on display unit 8 as shown in FIG. 15. Contrast image 200 can be selected, for example, from contrast images 2111-211a included in image group 21 (or contrast images 2211-221b included in image group 22). Furthermore, a contrast image may be selected from the three contrast images selected in step ST1 (contrast image 2114 of contrast phase T1, contrast image 211a of the early phase, and contrast image 2212 of the late phase). After selecting contrast image 200, a user adds a region of interest to contrast image 200 at a location where the user wants to check the timing at which the contrast agent is discharged.

[0084] FIG. 16 is an explanatory diagram of the region of interest 45. The user operates the user interface 10 to input a command to add a region of interest 45 to a location (e.g., a target) where the user wishes to check the timing at which the contrast agent is discharged. When the user interface 10 accepts the user's input to add a region of interest 45, the processor adds the region of interest 45 to the contrast image 200. The region of interest 45 is, for example, a region that includes the target. Once the region of interest 45 has been added to the contrast image 200, the process proceeds to step ST52.

[0085] In step ST52, the processor selects a pixel from within the region of interest 45 and determines a color to be assigned to the selected pixel. Here, an example of assigning the color of pixel P1 within the region of interest 45 will be described.

[0086] FIG. 17 is an explanatory diagram of a procedure for determining the color to be assigned to pixel P1 in region of interest 45. The processor reads out the average brightness B22 of the liver parenchyma (region of interest 51) of the contrast-enhanced image 211a in the early phase T2 from the memory. The processor also reads out the brightness value B221 of the pixel P21 from the contrast-enhanced image 211a in the early phase T2. This pixel P21 is a pixel corresponding to the pixel P1 of the region of interest 45 of the contrast-enhanced image 200. The processor then calculates a difference value ΔE between the average brightness B22 of the liver parenchyma and the brightness value B221 of the pixel P21. When calculating the difference value ΔE, the difference value ΔE (=B22-B221) may be calculated by subtracting the brightness value B221 of the pixel P21 from the average brightness B22 of the liver parenchyma, or the difference value ΔE (=B221-B22) may be calculated by subtracting the average brightness B22 of the liver parenchyma from the brightness value B221 of the pixel P21. In this embodiment, the difference value ΔE is calculated by subtracting the brightness value of the pixel from the average brightness of the liver parenchyma. Therefore, the processor calculates a difference value ΔE (=B22−B221) by subtracting the brightness value B221 of the pixel P21 from the average brightness B22 of the liver parenchyma.

[0087] The processor also reads out the average brightness B32 of the liver parenchyma (region of interest 51) of the contrast image 2212 in the late phase T3 from the memory, and further reads out the brightness value B331 of the pixel P31 of the contrast image 2212 in the late phase T3. This pixel P31 is a pixel corresponding to the pixel P1 of the region of interest 45 of the contrast image 200. Then, the processor calculates a difference value ΔL between the average brightness B32 of the liver parenchyma and the brightness value B331 of the pixel P31. When calculating the difference value ΔL, the difference value ΔL (=B32-B331) may be calculated by subtracting the brightness value B331 of the pixel P31 from the average brightness B32 of the liver parenchyma, or the difference value ΔL (=B331-B32) may be calculated by subtracting the average brightness B32 of the liver parenchyma from the brightness value B331 of the pixel P31. In this embodiment, the difference value ΔL is calculated by subtracting the brightness value of the pixel from the average brightness of the liver parenchyma, similar to the difference value ΔE. Therefore, the processor calculates a difference value ΔL (=B32−B331) by subtracting the luminance value B331 of the pixel P31 from the average luminance B32 of the liver parenchyma.

[0088] Then, the processor determines the color to be assigned to pixel P1 (see FIG. 16) in the region of interest 45 based on a combination of these two difference values ​​ΔE (=B22-B221) and ΔL (=B32-B331).

[0089] 18 to 21 are explanatory diagrams of a method for determining the color to be assigned to pixel P1 in region of interest 45 based on two difference values ​​ΔE and ΔL.

[0090] The processor determines the color to be assigned to pixel P1 from within color map 81 based on the two difference values ​​ΔE and ΔL.

[0091] The color map 81 is stored in a memory. The horizontal axis of the color map 81 represents the difference value ΔE in the early phase T2, and the vertical axis represents the difference value ΔL in the late phase T3. The difference values ​​ΔE and ΔL may take negative values, but when the difference values ​​ΔE and ΔL are negative values, they are considered to be "zero" on the color map 81.

[0092] The color map 81 represents the color determined by the combination of two difference values ΔE and ΔL. For example, when the difference value ΔE is ΔE = ΔEa and the difference value ΔL is ΔL = ΔLa, the color determined by this combination of difference values is Ca. Therefore, the color can be determined by the combination of two difference values ΔE and ΔL. Incidentally, the color map 81 can determine thousands to tens of thousands of colors according to the combination of two difference values ΔE and ΔL. Here, for the sake of convenience of explanation, as shown in FIG. 19, the area of the color map 81 is divided into three areas 82, 83, and 84, and it is assumed that red, yellow, and blue are assigned to the areas 82, 83, and 84, respectively.

[0093] Therefore, in the present embodiment, each pixel of the region of interest 45 is assigned a color selected from red, yellow, and blue.

[0094] Returning to FIG. 17, the difference value ΔE in the early phase T2 is ΔE = B22 - B221, and the difference value ΔL in the late phase T3 is ΔL = B32 - B331. Therefore, the processor determines the color to be assigned to the pixel P1 based on the combination of the difference value ΔE = B22 - B221 and the difference value ΔL = B32 - B331.

[0095] FIG. 20 is an explanatory diagram when determining the color based on the difference value ΔE = B22 - B221 and the difference value ΔL = B32 - B331.

[0096] The difference value ΔE in the early phase T2 is ΔE = B22 - B221. Here, B22 < B221 (see FIG. 17). Therefore, since ΔE = B22 - B221 is a negative value, the processor determines that ΔE = B22 - B221 is "zero".

[0097] On the other hand, the difference value ΔL in the late phase T3 is ΔL = B32 - B331. Here, since B32 > B331 (see FIG. 17), ΔL = B32 - B331 is a positive value. Therefore, the processor identifies the point of (B32 - B331) from the axis ΔL.

[0098] Therefore, the processor can identify a color C1 that corresponds to the combination of the difference value ΔE=B22-B221 and the difference value ΔL=B32-B331 from within the color map 81. Since the color C1 is included in the region 82, the color C1 represents red. Therefore, the processor assigns red as the color in the pixel P1 of the region of interest 45. After determining the color to be assigned, the process proceeds to step ST53.

[0099] In step ST53, the processor determines whether or not all pixels have been selected from the region of interest 45. Here again, only pixel P1 has been selected, so the process returns to step ST52. The processor then determines the colors to be assigned to the other pixels in a similar manner.

[0100] FIG. 21 is an explanatory diagram for determining the color to be assigned to pixel P2 in region of interest 45. In FIG. The processor reads out from the memory an average brightness B22 of the liver parenchyma (region of interest 51) of the contrast-enhanced image 211a in the early phase T2. The processor also reads out a brightness value B222 of a pixel P22 from the contrast-enhanced image 211a in the early phase T2. This pixel P22 corresponds to pixel P2 (see FIG. 16) in the region of interest 45 of the contrast-enhanced image 200. The processor then calculates a difference value ΔE (=B22-B222) by subtracting the brightness value B222 of pixel P22 from the average brightness B22 of the liver parenchyma.

[0101] The processor also reads out from the memory an average brightness B32 of the liver parenchyma (region of interest 51) of the contrast-enhanced image 2212 in the late phase T3, and further reads out a brightness value B332 of a pixel P32 from the contrast-enhanced image 2212 in the late phase T3. This pixel P32 corresponds to the pixel P2 of the region of interest 45 of the contrast-enhanced image 200. The processor then calculates a difference value ΔL (=B32−B332) by subtracting the brightness value B332 of the pixel P32 from the average brightness B32 of the liver parenchyma.

[0102] Therefore, two difference values, ΔE (= B22 - B222) and ΔL (= B32 - B332), can be calculated.

[0103] After calculating the two difference values ΔE and ΔL, the processor determines the color to be assigned to the pixel P2 (see FIG. 16) in the region of interest 45 based on these two difference values ΔE (= B22 - B222) and ΔL (= B32 - B332).

[0104] FIG. 22 is an explanatory diagram when determining the color based on the difference value ΔE = B22 - B222 and the difference value ΔL = B32 - B332. The difference value ΔE in the early phase T2 is ΔE = B22 - B222. Here, B22 < B222 (see FIG. 21). Therefore, since ΔE = B22 - B222 is a negative value, the processor determines that ΔE = B22 - B222 is "zero".

[0105] Also, the difference value ΔL in the late phase T3 is ΔL = B32 - B332. Here, since B32 < B332 (see FIG. 21), ΔL = B32 - B332 is a negative value. Therefore, the processor determines that ΔL = B32 - B332 is "zero".

[0106] Therefore, the processor can identify the color C2 corresponding to the combination of the difference value ΔE = B22 - B222 and the difference value ΔL = B32 - B332 from the color map 81. Since the color C2 is included in the region 84, the color C2 represents blue. Therefore, the processor assigns blue as the color at the pixel P2 in the region of interest 45. After determining the color to be assigned, it proceeds to step ST53.

[0107] In step ST53, the processor determines whether all the pixels have been selected from the region of interest 45. Here, since only the pixels P1 and P2 have been selected, it returns to step ST52.

[0108] Similarly, for other pixels, the processor determines the color to be assigned based on the combination of the two difference values ​​ΔE and ΔL.

[0109] Therefore, a color can be assigned to each pixel in the region of interest 45. If it is determined in step ST53 that all pixels have been selected, the process proceeds to step ST54, where a WO image is created and displayed. Figure 23 is a schematic diagram showing a WO image.

[0110] An example in which the brightness of the target is decreased in the late phase (contrast agent is discharged) is shown in Fig. 23. When the WO image is displayed, the flow in Fig. 5 ends. The WO image can express the timing of contrast agent discharge with color, so that the user can easily visually recognize the timing of the decrease in the brightness of the target by looking at the WO image.

[0111] In the above example, a case where the target has good staining has been described. Next, a case where the target has poor staining will be described with reference to the flow in FIG.

[0112] In step ST1, similarly to the method described above, contrast-enhanced images of the enhancement phase T1, early phase T2, and late phase T3 are selected, and regions of interest are assigned.

[0113] FIG. 24 is an explanatory diagram of step ST1. The processor selects the contrast-enhanced image 2114 of the contrast phase T1, the contrast-enhanced image 211a of the early phase T2, and the contrast-enhanced image 2212 of the late phase T3, and assigns the regions of interest 41 and 51 to obtain data groups 91 and 93 representing the time change in average brightness in the target and data groups 92 and 94 representing the time change in average brightness in the liver parenchyma. A data group 91 represents a data group of the target acquired during a data acquisition period SC1, and a data group 93 represents a data group of the target acquired during a data acquisition period SC2. A data group 92 represents a data group of the liver parenchyma acquired during the data acquisition period SC1, and a data group 94 represents a data group of the liver parenchyma acquired during the data acquisition period SC2. Fig. 24 shows a case of poor target contrast, in which the average brightness of the target is lower than the average brightness of the liver parenchyma across contrast phase T1, early phase T2, and late phase T3.

[0114] Once the average brightness of the target and the average brightness of the liver parenchyma in the contrast-enhanced phase T1, early phase T2, and late phase T3 have been obtained, proceed to step ST2.

[0115] In step ST2, the processor obtains a magnitude relationship between the average brightness of the target and the average brightness of the liver parenchyma for each of the enhancement phase T1, the early phase T2, and the late phase T3. In this embodiment, a case will be described in which the difference value between the average brightness of the target and the average brightness of the liver parenchyma is calculated as the magnitude relationship between the average brightness of the target and the average brightness of the liver parenchyma.

[0116] FIG. 25 is an explanatory diagram of a method for calculating the difference value. The processor calculates a difference value Δ1 between the average brightness B13 of the target region of interest 41 in the contrast image 2114 at the contrast enhancement phase T1 (i.e., the average brightness B13 represented by the data D13) and the average brightness B13 of the liver parenchyma region of interest 51 (i.e., the average brightness B14 represented by the data D14). When calculating the difference value Δ1, the difference value Δ1 (=B14-B13) may be calculated by subtracting the average brightness B13 of the target region of interest 41 from the average brightness B14 of the liver parenchyma region of interest 51, or the difference value Δ1 (=B13-B14) may be calculated by subtracting the average brightness B14 of the liver parenchyma region of interest 51 from the average brightness B13 of the target region of interest 41. In this embodiment, the difference value Δ1 is calculated by subtracting the average brightness of the target region of interest 41 from the average brightness of the liver parenchyma region of interest 51. Therefore, the processor calculates a difference value Δ1 (=B14−B13) by subtracting the average brightness B13 of the target region of interest 41 from the average brightness B14 of the region of interest 51 of the liver parenchyma.

[0117] The processor also calculates a difference value Δ2 between the average brightness B23 of the target region of interest 41 in the contrast image 211a of the early phase T2 (i.e., the average brightness B23 represented by the data D23) and the average brightness B24 of the liver parenchyma region of interest 51 (i.e., the average brightness B24 represented by the data D24). When calculating the difference value Δ2, the difference value Δ2 (=B24-B23) may be calculated by subtracting the average brightness B23 of the target region of interest 41 from the average brightness B24 of the liver parenchyma region of interest 51, or the difference value Δ2 (=B23-B24) may be calculated by subtracting the average brightness B24 of the liver parenchyma region of interest 51 from the average brightness B23 of the target region of interest 41. In this embodiment, similar to the difference value Δ1, the difference value Δ2 is calculated by subtracting the average brightness of the target region of interest 41 from the average brightness of the liver parenchyma region of interest 51. Therefore, the processor calculates a difference value Δ2 (=B24−B23) by subtracting the average brightness B23 of the target region of interest 41 from the average brightness B24 of the region of interest 51 of the liver parenchyma.

[0118] Furthermore, the processor calculates a difference value Δ3 between the average brightness B33 of the target region of interest 41 in the contrast image 2212 of the late phase T3 (i.e., the average brightness B33 represented by the data D33) and the average brightness B34 of the liver parenchyma region of interest 51 (i.e., the average brightness B34 represented by the data D34). When calculating the difference value Δ3, the difference value Δ3 (=B34-B33) may be calculated by subtracting the average brightness B33 of the target region of interest 41 from the average brightness B34 of the liver parenchyma region of interest 51, or the difference value Δ3 (=B33-B34) may be calculated by subtracting the average brightness B34 of the liver parenchyma region of interest 51 from the average brightness B33 of the target region of interest 41. In this embodiment, similar to the difference value Δ1, the difference value Δ3 is calculated by subtracting the average brightness of the target region of interest 41 from the average brightness of the liver parenchyma region of interest 51. Therefore, the processor calculates a difference value Δ3 (=B34−B33) by subtracting the average brightness B33 of the target region of interest 41 from the average brightness B34 of the region of interest 51 of the liver parenchyma. After calculating these difference values ​​Δ1, Δ2, and Δ3, the process proceeds to step ST3.

[0119] In step ST3, the processor determines whether all the difference values ​​Δ1, Δ2, and Δ3 are positive (or negative).

[0120] In the contrast phase T1, the average brightness B14 of the liver parenchyma is greater than the average brightness B13 of the target (B14>B13). Therefore, the difference value Δ1>0.

[0121] In the early phase T2, the average brightness B24 of the liver parenchyma is greater than the average brightness B23 of the target (B24>B23). Therefore, the difference value Δ2>0.

[0122] In the late phase T3, the average brightness B34 of the liver parenchyma is greater than the average brightness B33 of the target (B34>B33). Therefore, the difference value Δ3>0.

[0123] Therefore, the three difference values ​​Δ1, Δ2, and Δ3 are positive. Therefore, it is determined that the difference values ​​Δ1, Δ2, and Δ3 are all positive. When the difference values ​​Δ1, Δ2, and Δ3 are all positive, it is considered that the target is not sufficiently stained. In this case, as in the case where the target is well stained, if a WO image is obtained using the difference value between the target and the liver parenchyma, it is difficult to obtain a suitable WO image because a large difference is unlikely to appear between the difference value between the target and the liver parenchyma in the early phase and the difference value between the target and the liver parenchyma in the late phase. Therefore, in this embodiment, if it is determined that all the difference values ​​Δ1, Δ2, and Δ3 are positive (or negative), the process proceeds to step ST6, and the processor determines to create a WO image based on the time change in the brightness (feature amount) of the target without using the difference value between the target and the liver parenchyma. Then, the process proceeds to step ST5. Step ST5 will be described with reference to the flow of FIG. 14.

[0124] In step ST51, the user displays contrast image 200 on display unit 8, as shown in Fig. 26, and adds a region of interest 45 in contrast image 200. After region of interest 45 has been added to contrast image 200, the process proceeds to step ST52.

[0125] In step ST52, the processor determines a color to be assigned to each pixel in the region of interest 45. Step ST52 will be described below.

[0126] In step ST52, the processor selects a pixel from within the region of interest 45 and determines a color to be assigned to the selected pixel. Here, an example of assigning the color of pixel Q1 within the region of interest 45 will be described.

[0127] FIG. 27 is an explanatory diagram of a method for determining the colors to be assigned. The processor reads out a brightness value B13 of a pixel Q13 from the contrast-enhanced image 2114 at the contrast phase T1. The pixel Q13 corresponds to the pixel Q1 in the region of interest 45 of the contrast-enhanced image 200.

[0128] The processor also reads out a brightness value B23 of a pixel Q23 from the contrast-enhanced image 211a in the early phase T2. The pixel Q23 corresponds to the pixel Q1 in the region of interest 45 of the contrast-enhanced image 200.

[0129] The processor calculates a difference value ΔE between the luminance value B13 of the contrast phase T1 and the luminance value B23 of the early phase T2. When calculating the difference value ΔE, the difference value ΔE (=B13-B23) may be calculated by subtracting the luminance value B23 of the early phase T2 from the luminance value B13 of the contrast phase T1, or the difference value ΔE (=B23-B13) may be calculated by subtracting the luminance value B13 of the contrast phase T1 from the luminance value B23 of the early phase T2. In this embodiment, the difference value ΔE is calculated by subtracting the luminance value of the early phase T2 from the luminance value of the contrast phase T1. Therefore, the processor calculates the difference value ΔE (=B13-B23) by subtracting the luminance value B23 of the early phase T2 from the luminance value B13 of the contrast phase T1.

[0130] The processor also reads out the brightness value B33 of pixel Q33 from the contrast image 2212 in the late phase T3. This pixel Q33 is a pixel corresponding to pixel Q1 in the region of interest 45 of the contrast image 200. The processor then calculates a difference value ΔL between the brightness value B13 in the contrast phase T1 and the brightness value B33 in the late phase T3. When calculating the difference value ΔL, the difference value ΔL (=B13-B33) may be calculated by subtracting the brightness value B33 in the late phase T3 from the brightness value B13 in the contrast phase T1, or the difference value ΔL (=B33-B13) may be calculated by subtracting the brightness value B13 in the contrast phase T1 from the brightness value B33 in the late phase T3. In this embodiment, the difference value ΔL is calculated by subtracting the brightness value in the late phase T3 from the brightness value in the contrast phase T1. Therefore, the processor calculates a difference value ΔL (=B13−B33) by subtracting the luminance value B33 of the late phase T3 from the luminance value B13 of the enhancement phase T1.

[0131] Then, the processor determines the color to be assigned to pixel Q1 (see FIG. 26) in the region of interest 45 based on a combination of the two difference values ​​ΔE (=B13-B23) and ΔL (=B13-B33).

[0132] FIG. 28 is an explanatory diagram for determining the color to be assigned to pixel Q1 based on two difference values ​​ΔE (=B13-B23) and ΔL (=B13-B33).

[0133] The processor determines the color to be assigned to pixel Q1 from within color map 81 based on the two difference values ​​ΔE and ΔL.

[0134] The color map 81 is stored in a memory. The horizontal axis of the color map 81 represents the difference value ΔE between the contrast-enhanced phase T1 and the early phase T2, and the vertical axis represents the difference value ΔL between the contrast-enhanced phase T1 and the late phase T3. Note that the color map 81 can determine thousands to tens of thousands of colors according to the combination of the two difference values ​​ΔE and ΔL. However, for convenience of explanation, the area of ​​the color map 81 is divided into three areas 82, 83, and 84 as shown in FIG. 28, and red, yellow, and blue are assigned to the areas 82, 83, and 84, respectively.

[0135] Thus, in this embodiment, each pixel of region of interest 45 is assigned a color selected from among red, yellow, and blue.

[0136] As shown in FIG. 27, the difference value ΔE between the contrast-enhanced phase T1 and the early phase T2 is ΔE=B13-B23, and the difference value ΔL between the contrast-enhanced phase T1 and the late phase T3 is ΔL=B13-B33. Therefore, the processor can specify a color C1 corresponding to the combination of the difference value ΔE=B13-B23 and the difference value ΔL=B13-B33 from the color map 81. Since the color C1 is included in the region 83, the color C1 represents yellow. Therefore, the processor assigns yellow as the color in the pixel Q1 of the region of interest 45. After determining the color to be assigned, the process proceeds to step ST53.

[0137] In step ST53, the processor determines whether or not all pixels have been selected from the region of interest 45. In this case, since only pixel Q1 has been selected, the processor returns to step ST52 and similarly assigns a color to each pixel.

[0138] 29 shows two other pixels, pixel Q2 assigned a color C2 and pixel Q3 assigned a color C3, where C2 is red and C3 is blue.

[0139] Similarly, for other pixels, the processor determines the color to be assigned based on the combination of the two difference values ​​ΔE and ΔL.

[0140] Therefore, a color can be assigned to each pixel in the region of interest 45. If it is determined in step ST53 that all pixels have been selected, the process proceeds to step ST54, where a WO image is created and displayed. FIG. 30 is a schematic diagram showing a WO image. FIG. 30 shows an example in which the brightness of the target is reduced in the early phase. In this way, a WO image can be created.

[0141] In this embodiment, in cases where the target is well stained, a WO image is created using both the target data and the liver parenchyma data (using the difference value between the liver parenchyma and the target). On the other hand, in cases where the target is poorly stained, if a WO image is obtained using both the target data and the liver parenchyma data, as in cases where the target is well stained, it is difficult to obtain a high-quality WO image because a large difference is unlikely to appear between the difference value between the target and the liver parenchyma in the early phase and the difference value between the target and the liver parenchyma in the late phase. Therefore, in this embodiment, in cases where the target is poorly stained, a WO image is created using only the brightness of the target without using the brightness of the liver parenchyma. Therefore, even in cases where the target is poorly stained, a WO image suitable for determining in which phase the contrast agent was discharged from the target can be obtained.

[0142] In addition, in this embodiment, in cases where the target is well stained, the color to be assigned to the pixel is determined based on the difference value in the early phase and the difference value in the late phase. Therefore, the color is assigned based on the difference value of both the early phase and the late phase, not only the difference value in the early phase (or the late phase), so that the color can be determined by reflecting the information of both the early phase and the late phase, and a high-quality WO image can be obtained.

[0143] In addition, in this embodiment, a WO image is created based on contrast images of the contrast-enhanced phase T1, early phase T2, and late phase T3. However, if a WO image can be created, a WO image may be created using a contrast image of another phase instead of the contrast images of these phases.

[0144] In this embodiment, the contrast image of the contrast phase T1 is selected as the contrast image of the contrast phase T1 when the luminance of the target is at its peak. However, as long as it is possible to select a contrast image of a phase in which the target is sufficiently contrasted with the contrast agent, the contrast image of the contrast phase T1 is not necessarily limited to the contrast image of the peak phase, and an image of a phase shifted from the peak may be selected as the contrast image of the contrast phase. For example, a contrast image of a phase when the difference between the luminance of the target and the luminance of the liver parenchyma is maximum may be selected as the contrast image of the contrast phase T1.

[0145] In this embodiment, the contrast image of the late phase T3 is selected as the contrast image of about 5 minutes after the administration of the contrast agent. However, the contrast image of the late phase T3 is not limited to the contrast image of about 5 minutes after the administration of the contrast agent. For example, the contrast image of about 10 minutes after the administration of the contrast agent may be selected as the contrast image of the late phase T3. [Explanation of symbols]

[0146] 1. Ultrasound diagnostic equipment 2 Ultrasound probe 2a Vibration element 3. Transmit Beamformer 4 Transmitter 5 Receiver 6 Receive beamformer 7 Processors 8 Display 9. Memory 10 User Interface 20 Thumbnail Area 21, 22, 23, 2n Image Group 40 Image display area 41, 42, 43, 44, 45, 51, 53 Areas of interest 56 Operator 57 Subject 60 TIC area 61, 62, 63, 64 Data set 71, 72 hour intensity curve 81 Color Map 82, 83, 84 area 91, 92, 93, 94 Data set 200 contrast images

Claims

1. 1. An ultrasound diagnostic device including one or more processors, the one or more processors: selecting, from a plurality of contrast images acquired from a cross section including a target of a subject to which a contrast agent has been administered, a first contrast image showing a state in which the target is stained in a first time phase, a second contrast image for determining whether or not the contrast agent has been discharged from the target in a second time phase after the first time phase, and a third contrast image for determining whether or not the contrast agent has been discharged from the target in a third time phase after the second time phase; identifying a first magnitude relationship between a feature amount of the target in the first contrast image and a feature amount of a tissue compared to the target, a second magnitude relationship between the feature amount of the target in the second contrast image and a feature amount of the tissue, and a third magnitude relationship between the feature amount of the target in the third contrast image and a feature amount of the tissue; generating an image for determining whether or not the contrast agent has been expelled from the target in the second and third time phases based on a time change in the feature amount of the target, when all of the first magnitude relationship, the second magnitude relationship, and the third magnitude relationship indicate that the feature amount of the target is greater than the feature amount of the tissue, or that the feature amount of the target is smaller than the feature amount of the tissue; 2. An ultrasound diagnostic device comprising:

2. the first magnitude relationship represents a first difference value between a feature amount of the region of interest of the target and a feature amount of the region of interest of the tissue in the first contrast image; the second magnitude relationship represents a second difference value between a feature amount of the region of interest of the target and a feature amount of the region of interest of the tissue in the second contrast image; The ultrasound diagnostic apparatus of claim 1 , wherein the third magnitude relationship represents a third difference value between a feature amount of the region of interest of the target and a feature amount of the region of interest of the tissue in the third contrast image.

3. When the user interface receives a user command to add a region of interest to a contrast-enhanced image, the one or more processors add the region of interest to the contrast-enhanced image; The ultrasonic diagnostic apparatus according to claim 1 , wherein the region of interest is set at a location where a user wants to check timing of contrast agent discharge.

4. The one or more processors: selecting a first pixel from the region of interest applied to the contrast enhanced image; reading out a feature amount of the tissue of the second contrast image in the second time phase; reading out a luminance value of a second pixel corresponding to a first pixel of the second contrast-enhanced image from the second contrast-enhanced image at the second time phase; calculating a fourth difference value between the feature amount of the tissue of the second contrast image at the second time phase and a luminance value of the second pixel; reading out a feature amount of the tissue of the third contrast image in the third time phase; reading out a luminance value of a third pixel corresponding to a first pixel of the third contrast-enhanced image from the third contrast-enhanced image at the third time phase; calculating a fifth difference value between the feature amount of the tissue of the third contrast image at the third time phase and a luminance value of the third pixel; The ultrasound diagnostic apparatus of claim 3 , further comprising: a processor configured to assign a color to a first pixel of the contrast image based on a combination of the fourth difference value and the fifth difference value.

5. A color map is stored in the memory; The one or more processors:

5. The ultrasonic diagnostic apparatus according to claim 4, further comprising: a color corresponding to a combination of the fourth difference value and the fifth difference value from within the color map; and the identified color is assigned as a color of the first pixel.

6. The one or more processors: selecting a first pixel from the region of interest of the contrast enhanced image; reading out, from the first contrast-enhanced image at the first time phase, a brightness value of a second pixel corresponding to the first pixel of the contrast-enhanced image; reading out a luminance value of a third pixel corresponding to the first pixel of the second contrast-enhanced image from the second contrast-enhanced image at the second time phase; reading out a luminance value of a fourth pixel corresponding to the first pixel of the third contrast-enhanced image from the third contrast-enhanced image at the third time phase; calculating a fourth difference value between the luminance value of the second pixel and the luminance value of the third pixel; calculating a fifth difference value between the luminance value of the second pixel and the luminance value of the fourth pixel; The ultrasound diagnostic apparatus of claim 3 , further comprising: a processor configured to assign a color to a first pixel of the contrast image based on a combination of the fourth difference value and the fifth difference value.

7. A color map is stored in the memory; The one or more processors: The ultrasonic diagnostic apparatus according to claim 6, further comprising: identifying a color corresponding to a combination of the fourth difference value and the fifth difference value from within the color map; and assigning the identified color as a color in the first pixel.

8. 7. The ultrasonic diagnostic apparatus according to claim 4, wherein the second time phase is an early phase, and the third time phase is a late phase.

9. The ultrasound diagnostic apparatus according to claim 2 , wherein the feature amount is an average luminance within a region of interest.

10. The ultrasound diagnostic apparatus of claim 1 , wherein the target is a tumor and the tissue is liver parenchyma.

11. One or more non-transitory computer-readable storage media having stored thereon one or more instructions executable by one or more processors, the one or more instructions causing the one or more processors to: selecting, from a plurality of contrast images acquired from a cross section including a target of a subject to which a contrast agent has been administered, a first contrast image showing a state in which the target is stained in a first time phase, a second contrast image for determining whether or not the contrast agent has been discharged from the target in a second time phase after the first time phase, and a third contrast image for determining whether or not the contrast agent has been discharged from the target in a third time phase after the second time phase; identifying a first magnitude relationship between a feature amount of the target in the first contrast image and a feature amount of a tissue compared to the target, a second magnitude relationship between the feature amount of the target in the second contrast image and a feature amount of the tissue, and a third magnitude relationship between the feature amount of the target in the third contrast image and a feature amount of the tissue; generating an image for determining whether or not the contrast agent has been expelled from the target in the second and third time phases based on a time change in the feature amount of the target, when all of the first magnitude relationship, the second magnitude relationship, and the third magnitude relationship indicate that the feature amount of the target is greater than the feature amount of the tissue, or that the feature amount of the target is smaller than the feature amount of the tissue; A storage medium that executes the above.

Images