JP6230801B2 - Ultrasonic imaging apparatus and ultrasonic image display method - Google Patents

Description

  The present invention relates to an ultrasonic imaging apparatus and an ultrasonic image display method, and more particularly to an ultrasonic imaging apparatus and an ultrasonic image display method for displaying a tomographic image in a subject using ultrasonic waves.

  A conventional ultrasonic imaging apparatus transmits an ultrasonic wave inside a subject by an ultrasonic probe, receives an ultrasonic reflected echo signal corresponding to the structure of a living tissue from the inside of the subject, and generates a tomography in the subject. Configure and display the image.

  In addition, an ultrasonic diagnostic apparatus is disclosed that sets a measurement target and generates a graph that represents a transition of a compression state applied to the measurement target based on the position change of the set measurement target (see Patent Document 1). ).

  In addition, the ultrasonic tomographic data of the tomographic site of the subject is measured by applying pressure to the subject, and a physical quantity that correlates with the elasticity of the tissue at the tomographic site is obtained based on the ultrasonic tomographic data. An ultrasonic diagnostic apparatus that generates an elasticity image and displays the elasticity image on a display device, obtains compression state information regarding a compression state of a tomographic site based on pressure applied to the subject, and displays the compression state information on the display device together with the elasticity image. It is disclosed (see Patent Document 2).

WO2009 / 104657 Publication WO2005 / 120358 Publication

  In the conventional ultrasonic imaging apparatus, the compression information (motion information and pressure information) of the observation region is affected by the state of the observation region (for example, the ratio of soft tissue to hard tissue). For example, the compression information that is output may differ between the case where the normal tissue is compressed and the case where the tumor tissue harder than the normal tissue is compressed even if the same compression is applied. In addition, a matching error may occur due to a decrease in S / N of the ultrasonic signal, and accurate movement information (such as displacement and displacement vector) may not be obtained.

  Even when an abnormal tissue having a hardness different from that of a normal tissue is present in the observation site, the present invention provides the same compression information as when the normal tissue is compressed without being affected by the state of the observation site. An ultrasonic imaging apparatus and an ultrasonic image display method that can be obtained are provided. Further, the present invention is similar to the case where compression is applied to normal tissue without being affected by the decrease in S / N even when a matching error occurs due to the decrease in S / N of the ultrasonic signal. An ultrasonic imaging apparatus and an ultrasonic image display method capable of obtaining compression information are provided.

  The ultrasonic imaging apparatus according to the present invention is based on at least one of an elasticity information calculation unit that calculates elasticity information of a part of the subject from ultrasound data of the subject, and the elasticity information and luminance information of the ultrasound data. A threshold value setting unit that sets at least one threshold value of an elasticity value and a luminance value, and a compression information generation unit that generates compression information of the region of the subject excluding an area corresponding to the set threshold value Prepare.

  According to this configuration, even when an abnormal tissue having a hardness different from that of the normal tissue is present in the observation site, the same compression as when the normal tissue is compressed without being affected by the state of the observation site. Information can be obtained. Further, the present invention is similar to the case where compression is applied to normal tissue without being affected by the decrease in S / N even when a matching error occurs due to the decrease in S / N of the ultrasonic signal. Compression information can be obtained.

  According to the present invention, even when an abnormal tissue having a hardness different from that of the normal tissue is present in the observation region, the same compression as that performed when the normal tissue is compressed without being affected by the state of the observation region. Information can be obtained. Further, according to the present invention, even when a matching error occurs due to a decrease in the S / N of the ultrasonic signal, the normal tissue is compressed without being affected by the decrease in the S / N. Similar compression information can be obtained.

It is the block diagram which showed an example of the ultrasonic imaging device of this Embodiment. It is the block diagram which showed an example of the threshold value setting part. It is a flowchart explaining operation | movement of the ultrasonic imaging device which produces | generates compression information based on the threshold value of an elasticity value or a luminance value. It is a figure explaining producing | generating the compression information of the site | part of a subject except the area | region corresponding to the threshold value of the set elasticity value. It is a figure explaining producing | generating the compression information of the site | part of a subject except the area | region corresponding to the threshold value of the set luminance value. It is a flowchart explaining operation | movement of the ultrasonic imaging device which produces | generates compression information based on the threshold value of a matching degree. It is a figure explaining producing | generating the compression information of the site | part of a test subject except the area | region corresponding to the threshold value of the set matching degree. FIG. 6 is a diagram showing that first compression information based on a threshold value of elasticity value and second compression information based on a threshold value of luminance value are respectively generated. It is a figure explaining selecting compression information acquisition field and generating compression information. It is a figure explaining performing a weighted average according to a plurality of fields corresponding to a plurality of thresholds.

  Hereinafter, an ultrasonic imaging apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram illustrating an example of the ultrasonic imaging apparatus according to the present embodiment. The ultrasonic imaging apparatus 1 may be used as an ultrasonic diagnostic apparatus.

  As shown in FIG. 1, the ultrasonic imaging apparatus 1 according to the present embodiment includes an ultrasonic probe (probe) 12 that is used in contact with a subject 10 and a subject via the ultrasonic probe 12. 10, a transmitter 14 that repeatedly transmits ultrasonic waves at time intervals, a receiver 20 that receives a time-series reflected echo signal generated from the subject 10, and an ultrasound that controls the transmitter 14 and the receiver 20 Transmission / reception control unit 18, phasing addition unit 22 for phasing and adding received reflected echoes to generate RF signal frame data as ultrasonic data (ultrasound tomographic data) in time series, phasing addition unit 22 Output from the tomographic image constructing unit 24 that composes a tomographic image based on the RF signal frame data generated in step 1, the image synthesizing unit 26 that synthesizes the tomographic image with other images, numerical information, and the like. Selects the image display unit 28 for displaying images and at least two RF signal frame data. An RF signal frame data selection unit 30 that performs measurement, a displacement measurement unit 32 that measures the displacement of the living tissue of the subject 10 using the selected RF signal frame data, and elasticity that obtains elasticity information from the measurement result of the displacement measurement unit 32 An information calculation unit 34, an elasticity image configuration unit 36 that configures an elasticity image from the elasticity information calculated by the displacement measurement unit 32, an operation unit 40 for an operator to operate, and a control unit 42 that controls each component With.

  The ultrasonic imaging apparatus 1 includes a threshold setting unit 50 that sets at least one threshold value of the elasticity value and the luminance value based on at least one of elasticity information and luminance information of the ultrasound data, and a threshold setting unit 50. A compression information generation unit 52 that generates compression information of a part of the subject 10 except for a region corresponding to the set threshold value, and executes a region exclusion function. The compression information is an index representing the compression state of the observation site or a spatial and temporal change of this index. The compression information includes movement information and pressure information of the observation region, for example, physical quantities related to elasticity of the observation region (correlation of search unit, displacement, displacement vector, strain, elastic modulus, viscosity, etc.), distribution of this physical quantity, Includes physical quantity statistics (such as mean, deviation, variance, and coefficient of variation) and their spatial and temporal changes.

  Further, the ultrasonic imaging apparatus 1 includes a condition storage unit 54. The condition storage unit 54 stores ON / OFF settings for the area exclusion function, table settings for determining threshold values, and the like. A broken line shown in FIG. 1 indicates a main body of the ultrasonic imaging apparatus 1.

  The ultrasonic probe 12 is formed by arranging a plurality of transducers, and transmits and receives ultrasonic waves to and from the contacted subject 10 via the transducers. The transmission unit 14 generates a transmission pulse for driving the ultrasonic probe 12 to generate an ultrasonic wave, sets a convergence point of the transmitted ultrasonic wave to a certain depth, and Ultrasonic waves are repeatedly transmitted to the subject 10 via the child 12 at time intervals. The receiving unit 20 receives a time-series reflected echo signal generated from the subject 10 via the ultrasonic probe 12, amplifies the received reflected echo signal with a predetermined gain, and generates an RF signal (received signal). It has the function to generate. The ultrasonic transmission / reception control unit 18 controls the transmission unit 14 and the reception unit 20 to transmit / receive ultrasonic waves to / from the subject 10 via the ultrasonic probe 12. The phasing addition unit 22 performs phasing addition of the reflected echo signals received by the reception unit 20. The phasing / adding unit 22 inputs the RF signal amplified by the receiving unit 20 and performs phase control, forms an ultrasonic beam at one or more convergence points, and generates ultrasonic data (ultrasonic tomographic data). The RF signal frame data is generated in time series.

  The tomographic image construction unit 24 inputs data of a tomographic part of the subject 10 (for example, RF signal frame data from the phasing addition unit 22), and performs gain correction, log compression, detection, contour enhancement, filter processing, and the like. Signal processing is performed to construct tomographic image data (for example, a B-mode tomographic image of the subject 10). The tomographic image construction unit 24 includes an A / D converter that converts tomographic image data into a digital signal, a frame memory that stores a plurality of converted tomographic image data in time series, and a control controller. The tomographic image data in the subject 10 stored in the frame memory is acquired as one image, and the acquired tomographic image data is read out in synchronization with the television.

  The RF signal frame data selection unit 30 stores the RF signal frame data output from the phasing addition unit 22, and selects at least two (one set) of RF signal frame data from the stored RF signal frame data group. . For example, the RF signal frame data selection unit 30 sequentially stores the RF signal frame data generated in time series from the phasing addition unit 22 (that is, generated based on the frame rate of the image), and the stored RF Select signal frame data (N) as the first RF signal frame data, and from among the RF signal frame data group (N-1, N-2, N-3 …… NM) stored in the past in time Select one RF signal frame data (X). N, M, and X are index numbers given to the RF signal frame data, and are natural numbers.

  The displacement measuring unit 32 measures the displacement of the living tissue of the subject 10. Specifically, the displacement measuring unit 32 is obtained from a set of RF signal frame data selected by the RF signal frame data selecting unit 30 (that is, RF signal frame data (N) and RF signal frame data (X)), 1D or 2D correlation processing is performed, and a 1D or 2D displacement distribution (that is, 1D or 2 related to the direction and magnitude of the displacement) that is related to the displacement vector of the living tissue corresponding to each measurement point of the tomographic image Dimensional displacement distribution). Here, a block matching method or a phase gradient method is used to detect the displacement vector. In the block matching method, the displacement measuring unit 32 divides the image into blocks (search units) made up of N × N pixels, for example, and acquires compression information for acquiring compression information in a predetermined search region (for example, a site of the subject 10). Focus on the block (search unit) in the (region), search the previous (previous) frame for the block that most closely matches (matches) the target block in the current frame, and refer to this to predict the code Processing to determine the sample value by the conversion (difference). Thereby, the displacement of each measurement point of the tomographic image is obtained, and the displacement vector is detected. In the phase gradient method, the displacement measurement unit 32 calculates the movement amount of the wave from the wave phase information of the received signal, obtains the displacement of each measurement point of the tomographic image, and detects the displacement vector.

  The ultrasonic imaging apparatus 1 includes a pressure measurement unit (not shown). The pressure measurement unit is configured to measure the stress at each measurement point inside the subject 10 based on the pressure detected by the pressure sensor provided between the ultrasonic transmission / reception surface of the ultrasonic probe 12 and the subject 10. Measure.

  The elasticity information calculation unit 34 calculates elasticity information of the site of the subject from the ultrasound data of the subject. In the present embodiment, the elasticity information calculation unit 34 obtains elasticity information at the tomographic part of the subject 10 based on the ultrasonic data (ultrasound tomographic data) of the tomographic part of the subject 10. Elasticity information is a physical quantity related to elasticity such as displacement, displacement vector, strain, elastic modulus, and viscosity. For example, the elasticity information calculation unit 34 uses the RF signal frame data selected by the RF signal frame data selection unit 30, and based on the displacement (or displacement vector) of the living tissue measured by the displacement measurement unit 32 The elasticity information of the living tissue corresponding to each measurement point above is calculated. Further, the elasticity information calculation unit 34 receives the pressure value output from the pressure measurement unit, and calculates the elastic modulus of the living tissue using the pressure value at each measurement point inside the subject 10.

  The strain data is calculated by spatially differentiating the movement amount (displacement) of the living tissue. The elastic modulus data is calculated by dividing the change in pressure by the change in strain. For example, when the displacement measured by the displacement measuring unit 32 is L (X) and the pressure measured by the pressure measuring unit is P (X), the strain ΔS (X) is obtained by spatially differentiating L (X). Since it can be calculated, it is obtained using the equation: ΔS (X) = ΔL (X) / ΔX. Further, the Young's modulus Ym (X) of the elastic modulus data is obtained by the equation Ym = ΔP (X) / ΔS (X). Since the Young's modulus Ym determines the elastic modulus of the biological tissue corresponding to each measurement point of the tomographic image, two-dimensional elastic image data can be obtained continuously.

  The elasticity image construction unit 36 constructs an elasticity image at the tomographic site based on the elasticity information obtained by the elasticity information calculation unit 34. The elastic image construction unit 36 includes a frame memory and an image processing unit, stores elastic frame data in the frame memory, and performs image processing on the stored elastic frame data. The elastic image construction unit 36 has a function of adding hue information to the elastic frame data. Based on the elastic frame data, the three primary colors of light are red (R), green (G), and blue (B ) Is converted into elastic image data. For example, the elasticity image constructing unit 36 converts elasticity data of a part having a large distortion (soft) into a red code, and converts elasticity data of a part having a small distortion (hard) into a blue code.

  FIG. 2 is a block diagram showing an example of the threshold setting unit 50. As shown in FIG. The threshold setting unit 50 includes a condition setting unit 60, a region mask creation unit 62, a region calculation unit 64, and a time information holding unit 66.

  The condition setting unit 60 sets at least one threshold value of the elasticity value and the luminance value based on at least one of the elasticity information and the luminance information of the ultrasonic data. For example, the condition setting unit 60 reads a setting condition stored in advance in the condition storage unit 54 and sets a condition (threshold value) related to elasticity information calculated by the displacement measurement unit 32. The conditions (threshold values) set by the condition setting unit 60 relate to physical quantities relating to the elasticity of the observation region (correlation of search units, displacement, displacement vector, distortion, elastic modulus, viscosity, etc.), and the luminance of the ultrasonic data of the observation region. Physical quantities (such as brightness and brightness gradient), distribution of these physical quantities, statistics of these physical quantities (such as average, deviation, variance, and coefficient of variation for each search unit), and thresholds for these spatial and temporal changes .

  Based on the condition (threshold value) set by the condition setting unit 60, the area mask creation unit 62 generates an area mask for excluding an area corresponding to the set condition (threshold value). The area calculation unit 64 extracts the elasticity information of the area from which the area corresponding to the set condition (threshold value) is removed according to the area mask. The time information holding unit 66 holds time information for the compression information generating unit 52 to generate a temporal change in the compression information. For example, the time information holding unit 66 holds time information when each RF signal frame data is acquired.

  The compression information generation unit 52 generates the compression information of the part of the subject 10 except for the region corresponding to the set threshold value. For example, the compression information generation unit 52 indexes the compression information based on the average or deviation of elasticity information (for example, strain) extracted by the region calculation unit 64. In the indexing of the compression information, the compression information generation unit 52 converts the index indicating the compression state of the observation site into visual information such as a graph, a histogram, and an index meter based on the generated compression information, It is also possible to display the image on the image display unit 28 over time.

  The image composition unit 26 includes a frame memory, an image processing unit, and an image selection unit. The image composition unit 26 uses a technique represented by α blending to combine the tomographic image and the elasticity image, the synthesized image of the tomographic image and the compression information (including a graph of the compression information), and the elasticity image and the compression information. A composite image (including a compression information graph) is generated.

  The frame memory stores tomographic image data from the tomographic image construction unit 24, elastic image data from the elastic image construction unit 36, and time information for each RF signal frame from the time information holding unit 66. The image processing unit generates composite image data. The image selection unit selects an image from the tomographic image data in the frame memory, the elasticity image data, and the composite image data processed by the image processing unit, and causes the image display unit 28 to display the selected image.

  The image composition unit 26 is controlled by the control unit 42 based on the image display conditions set via the operation unit 40. The operation unit 40 includes operation devices such as a mouse, a keyboard, a trackball, a touch pen, and a joystick, and can set image display conditions and the like.

  The image display unit 28 displays a tomographic image, an elasticity image, a time variation image, and the like selected by the image selection unit of the image composition unit 26.

  Next, the operation of the ultrasonic imaging apparatus 1 of the present embodiment will be described. FIG. 3 is a flowchart for explaining the operation of the ultrasonic imaging apparatus 1 that generates compression information based on a threshold value of elasticity value or luminance value. FIG. 4 is a diagram for explaining the generation of the compression information of the region of the subject 10 excluding the region corresponding to the set elasticity value threshold value.

  As shown in FIG. 3, the elasticity information calculation unit 34 calculates the elasticity information of the site of the subject 10 from the ultrasound data of the subject 10, and the elasticity image construction unit 36 constructs an elasticity image from the elasticity information. Then, the image display unit 28 displays the tomographic image configured by the tomographic image configuration unit 24 and the composite image of the elastic image configured by the elastic image configuration unit 36 (step S100).

  For example, as shown in FIG. 4 (a), in the combined image of the tomographic image and the elastic image, the normal tissue 70 and the tumor tissue 72 in the tomographic image are displayed on the image display unit 28 based on the luminance information, and the normal in the elastic image The tissue 70 and the tumor tissue 72 are displayed on the image display unit 28 based on the elasticity information.

  Since the tumor tissue 72 and its surrounding tissue are harder than the normal tissue 70, the hardened tissue 74 in the elastic image (the tumor tissue 72 and its surrounding tissue) is superimposed on the tumor tissue 72 in the tomographic image and displayed on the image display unit 28. Is done. Assuming that the tumor tissue 72 is displayed in black based on the luminance information and the hardened tissue 74 is displayed in blue, the portion where the tumor tissue 72 and the hardened tissue 74 are overlapped is displayed in deep blue. The operator can observe the observation site on the assumption that the portion displayed in deep blue is likely to be a malignant tumor.

  According to the ON / OFF setting stored in the condition storage unit 54, the area exclusion function of the present embodiment is automatically turned ON / OFF, or according to the ON / OFF command by the operation unit 40 or another user interface. The area exclusion function is turned ON / OFF (step S102). When the area exclusion function is turned on, the process proceeds to S104, and when the area exclusion function is turned off, the process proceeds to S110.

  When the region exclusion function is turned on, the threshold setting unit 50 sets at least one threshold of the elasticity value and the luminance value based on at least one of the elasticity information and the luminance information of the ultrasonic data (Step S104). ). For example, as shown in FIG. 4 (b), the threshold setting unit 50 generates a histogram 81 of elasticity information values (elasticity values) at each measurement point, and elasticity values (for example, strain values) of hard tissue and soft tissue. ) Distribution. The threshold setting unit 50 (condition setting unit 60) sets an elastic value threshold 83 based on an elastic value distribution (histogram). The threshold setting unit 50 (condition setting unit 60) may set the threshold 83 based on the setting condition stored in advance in the condition storage unit 54, or may set the threshold 83 input from the operation unit 40. Good. The threshold setting unit 50 (condition setting unit 60) may set the threshold 83 based on the minimum value, maximum value, intermediate value, average, and the like of the elasticity value.

  In FIG. 4B, the threshold value setting unit 50 sets a threshold value 83 in the histogram 81 of elasticity values in order to exclude the region corresponding to the hardened tissue 74 (the tumor tissue 72 and its surrounding tissue). In addition, the threshold setting unit 50 may set the threshold 83 in a bar graph representing the elasticity value, or may set the threshold 83 by a numerical value of the elasticity value.

  Based on the condition (threshold 83) set by the threshold setting unit 50 (condition setting unit 60), the area mask creating unit 62 generates an area mask for excluding the region 84 corresponding to the set condition (threshold 83). Create (step S106). For example, as shown in FIG. 4C, the area mask creating unit 62 sets the area 84 corresponding to the elastic value (for example, strain value) equal to or less than the threshold 83 to “0” and the threshold 83 according to the set threshold 83. The region mask is generated so that the region 80 corresponding to the superelastic value becomes “1”. Thereby, a region mask for removing the region 84 corresponding to the hardened tissue 74 (the tumor tissue 72 and its surrounding tissue) is generated.

  The region calculation unit 64 extracts the elasticity information of the region 80 from which the region 84 corresponding to the set condition (threshold 83) is removed according to the region mask (step S108). The region calculation unit 64 extracts the elasticity information of the region 80 by multiplying the elasticity value by the value of the region mask (“0” or “1”).

  The compression information generation unit 52 generates compression information on the part of the subject 10 except for the region 84 corresponding to the set threshold 83 (step S110). For example, the compression information generation unit 52 indexes the compression information based on the average or deviation of elasticity information (for example, strain) extracted by the region calculation unit 64. In this way, even when an abnormal tissue (hardened tissue 74) having a hardness different from that of the normal tissue 70 exists in the observation site, by generating the compression information except for the region 84 corresponding to the hardened tissue 74, It is possible to obtain the same compression information as when the normal tissue 70 is compressed without being affected by the state of the observation site.

  Based on the generated compression information, the compression information generation unit 52 converts an index (average, deviation, etc.) indicating the compression state of the observation site into visual information such as a graph, a histogram, and an index meter, and then combines the images. The image synthesizing unit 26 synthesizes the visual information converted by the compression information generating unit 52 with the synthesized image of the tomographic image and the elasticity image, and displays it on the image display unit 28 (step S112). For example, as illustrated in FIG. 4D, the compression information generation unit 52 converts an index (for example, an average of elasticity values) indicating the compression state of the observation site into a time series graph 86.

For example, the average of the elasticity values is calculated by equation (1), and the standard deviation is calculated by equation (2).

  If the region exclusion function is turned off in step S102, the process proceeds to S110, and the compression information generation unit 52 does not exclude the region 84 corresponding to the set threshold 83, and displays the compression information of the site of the subject 10. Generate (step S110).

  As mentioned above, although embodiment concerning this invention was described, this invention is not limited to these, It can change and deform | transform within the range described in the claim.

  For example, in FIG. 4, the threshold value setting unit 50 sets a threshold value of the elasticity value based on the elasticity information, but the threshold value setting unit 50 determines the luminance value based on the luminance information (luminance, luminance gradient, etc.) of the ultrasonic data. The threshold value may be set.

  FIG. 5 is a diagram for explaining the generation of the compression information of the part of the subject 10 excluding the region corresponding to the set luminance value threshold. As shown in FIG. 5 (a), in the composite image of the tomographic image and the elastic image, the normal tissue 70 and the tumor tissue 72 in the tomographic image are displayed on the image display unit 28 based on the luminance information, and the normal tissue 70 in the elastic image is displayed. And the tumor tissue 72 are displayed on the image display unit 28 based on the elasticity information.

  As shown in FIG. 5 (b), when the region exclusion function is turned on, the threshold setting unit 50 sets the threshold of the luminance value based on the luminance information of the ultrasonic data (step S104). For example, the threshold setting unit 50 generates a histogram 91 of luminance information values (luminance values) at each measurement point, and generates luminance value distributions of a hard tissue (low luminance) and a soft tissue (high luminance). The threshold setting unit 50 (condition setting unit 60) sets an elastic value threshold 93 based on a luminance value distribution (histogram). The threshold setting unit 50 (condition setting unit 60) may set the threshold 93 based on the setting condition stored in advance in the condition storage unit 54, or may set the threshold 93 input from the operation unit 40. Good. The threshold setting unit 50 (condition setting unit 60) may set the threshold 93 based on the minimum value, maximum value, intermediate value, average, and the like of the luminance value.

  In FIG. 5B, the threshold value setting unit 50 sets a threshold value 93 in the histogram 91 of luminance values in order to exclude the region corresponding to the tumor tissue 72. In addition, the threshold value setting unit 50 may set the threshold value 93 in a bar graph representing the luminance value, or may set the threshold value 93 by a numerical value of the luminance value.

  Based on the condition (threshold 93) set by the threshold setting unit 50 (condition setting unit 60), the area mask creating unit 62 generates an area mask for excluding the region 92 corresponding to the set condition (threshold 93). Create (step S106). For example, as shown in FIG. 5 (c), the area mask creating unit 62 corresponds to the brightness value of the area 92 corresponding to the brightness value equal to or lower than the threshold value 93 and “0” according to the set threshold value 93. The region mask is generated so that the region 90 to be processed becomes “1”. Thereby, a region mask for removing the region 92 corresponding to the tumor tissue 72 is generated.

  The area calculation unit 64 extracts the elasticity information of the area 90 excluding the area 92 corresponding to the set condition (threshold 93) according to the area mask (step S108). The area calculation unit 64 extracts the elasticity information of the area 90 by multiplying the elasticity value by the area mask value (“0” or “1”).

  The compression information generation unit 52 generates compression information on the site of the subject 10 except for the region 92 corresponding to the set threshold 93 (step S110). For example, the compression information generation unit 52 indexes the compression information based on the average or deviation of elasticity information (for example, strain) extracted by the region calculation unit 64. Then, as shown in FIG. 5 (d), the compression information generation unit 52 converts an index (for example, an average of elasticity values) representing the compression state of the observation site into a time series graph 96 (step S112).

  In this way, even when an abnormal tissue (tumor tissue 72) having a hardness different from that of the normal tissue 70 exists in the observation site, by generating compression information except for the region 92 corresponding to the tumor tissue 72, It is possible to obtain the same compression information as when the normal tissue 70 is compressed without being affected by the state of the observation site.

  The ultrasonic imaging apparatus 1 further includes a matching information calculation unit (displacement measurement unit 32) that calculates matching information for each search unit from the ultrasonic data in the search region of the site of the subject 10, and the elasticity information calculation unit 34 includes: The elasticity information of the part of the subject 10 is calculated based on the matching information, and the threshold value setting unit 50 sets the threshold value of the matching degree (degree of matching) of the search unit based on the matching information, and the compression information generating unit 52 generates compression information on the part of the subject excluding the region corresponding to the set threshold value.

  For example, as described above, in the block matching method, the displacement measuring unit 32 pays attention to the block (search unit) in the search area and approximates (matches) the block of interest in the current frame most closely. Find the current block from the previous (past) frame. In this case, the displacement measurement unit 32 (matching information calculation unit) includes CC (Cross Correlation), SAD (Sum of Absolute Differences), SSD (Sum of Square Differences), SCD (Sum of Cubic Differences), and SPD (Sum of The matching information representing the degree of matching (approximation) is calculated by a technique such as Powered Differences), the displacement of each measurement point of the tomographic image is obtained, and the displacement vector is detected. That is, the displacement measurement unit 32 (matching information calculation unit) estimates the movement of the tissue for each micro block by matching the micro kernel, and calculates the displacement of the tissue. Based on the matching information, the elasticity information calculation unit 34 calculates the elasticity information of the site of the subject 10 from the tissue displacement.

  When acquiring the ultrasonic data of the normal tissue 70 and the tumor tissue 72 at the observation site of the subject 10, the ultrasonic probe (probe) 12 contacts the subject 10. However, since the S / N of the reflected echo signal reflected from the deep part of the observation site of the subject 10 and the S / N of the signal at both ends of the ultrasonic probe (probe) 12 tend to decrease, the S / N of the signal Due to a decrease in N, a search unit matching error may occur, and accurate movement information (such as displacement and displacement vector) may not be obtained. Therefore, in the present embodiment, the threshold setting unit 50 sets a threshold for the degree of matching for each search unit based on the matching information, and the compression information generating unit 52 excludes an area corresponding to the set threshold. Generate compression information on the part of the specimen.

  FIG. 6 is a flowchart for explaining the operation of the ultrasonic imaging apparatus 1 that generates compression information based on the matching degree threshold. FIG. 7 is a diagram for explaining the generation of the compression information of the region of the subject 10 excluding the region corresponding to the set matching degree threshold value.

  As shown in FIG. 6, the displacement measurement unit 32 (matching information calculation unit) calculates the search unit matching information from the ultrasound data in the search region of the site of the subject 10, and the elasticity information calculation unit 34 Based on the information, the elasticity information of the part of the subject is calculated, and the elasticity image constructing unit 36 constructs an elasticity image from the elasticity information. Then, the image display unit 28 displays the tomographic image configured by the tomographic image configuration unit 24 and the composite image of the elastic image configured by the elastic image configuration unit 36 (step S200).

  For example, as shown in FIG. 7 (a), in the composite image of the tomographic image and the elastic image, the normal tissue 70 and the tumor tissue 72 in the tomographic image are displayed on the image display unit 28 based on the luminance information, and the normal in the elastic image The tissue 70 and the tumor tissue 72 are displayed on the image display unit 28 based on the elasticity information.

  According to the ON / OFF setting stored in the condition storage unit 54, the area exclusion function of the present embodiment is automatically turned ON / OFF, or according to the ON / OFF command by the operation unit 40 or another user interface. The area exclusion function is turned ON / OFF (step S202). When the area exclusion function is turned on, the process proceeds to S204, and when the area exclusion function is turned off, the process proceeds to S210.

  When the region exclusion function is turned on, the threshold setting unit 50 sets a threshold for the matching degree for each search unit based on the matching information (step S204). For example, when the displacement measuring unit 32 (matching information calculating unit) calculates matching information by CC (Cross Correlation), as shown in FIG. The relationship 101) histogram 101 is generated, and a low correlation with a low S / N and a high correlation with a good S / N are generated. Matching reliability is low in a low-correlation low-reliability region where S / N is low, and matching reliability is high in a high-correlation high-reliability region with good S / N. The threshold setting unit 50 (condition setting unit 60) sets the threshold 103 for the matching degree (correlation coefficient) based on the distribution of the matching degree (correlation coefficient). The threshold setting unit 50 (condition setting unit 60) may set the threshold 103 based on the setting condition stored in advance in the condition storage unit 54, or may set the threshold 103 input from the operation unit 40. Good. Further, the threshold setting unit 50 (condition setting unit 60) may set the threshold 103 based on the minimum value, maximum value, intermediate value, average, and the like of the matching degree (correlation coefficient).

  In FIG. 7B, the threshold value setting unit 50 sets the threshold value 103 in the elasticity value histogram 101 in order to exclude the region corresponding to the low correlation in which the S / N is decreased. In addition, the threshold value setting unit 50 may set the threshold value 103 in a bar graph representing the elasticity value, or may set the threshold value 103 by a numerical value of the elasticity value.

  When the area exclusion function based on elasticity information or luminance information of the present embodiment is turned ON / OFF (step S205), and when the area exclusion function based on elasticity information or luminance information is turned OFF, the process proceeds to step S206, where elasticity information or luminance When the area exclusion function based on information is turned on, the process proceeds to step S304. In step S304, as shown in FIG. 4 (b) or FIG. 5 (b), the threshold setting unit 50 determines at least one of the elasticity value and the brightness value based on at least one of the elasticity information and the brightness information of the ultrasonic data. Set one threshold.

  The area mask creating unit 62 is for removing the low-reliability area 110 corresponding to the set condition (threshold 103) based on the condition (threshold 103) set by the threshold setting unit 50 (condition setting unit 60). A first area mask is created (steps S206 and S306). For example, as illustrated in FIG. 7C, the area mask creating unit 62 sets the low-reliability area 110 corresponding to the matching degree (for example, correlation coefficient) equal to or lower than the threshold 103 to “0” according to the set threshold 103. “The first region mask is generated so that the highly reliable region 100 corresponding to the matching degree exceeding the threshold value 103 becomes“ 1 ”. As a result, a first region mask for removing the low reliability region 110 corresponding to the low correlation in which the S / N is lowered is generated. By using the first area mask, even when a matching error occurred due to a decrease in the S / N of the ultrasonic signal, the normal tissue was compressed without being affected by the decrease in the S / N. The same compression information as the case can be obtained.

  In addition, when the threshold value of the elasticity value or the luminance value is set in step S304, as shown in FIG. 4 (c) or FIG. 5 (c), the area mask creation unit 62 sets the threshold value setting unit 50 (condition setting). Based on the condition (elastic value or luminance value threshold) set by the unit 60), the second area for excluding the area 84 or the region 92 corresponding to the set condition (elastic value or luminance value threshold) A mask is created (step S306). For example, the region mask creating unit 62 may correspond to the region 84 or the region corresponding to the elastic value or the luminance value equal to or less than the threshold 83 or the threshold 93 according to the threshold 83 or the threshold 93 set in FIG. 4B or 5B. The second region mask is generated so that the region 80 or the region 90 corresponding to the elasticity value or the luminance value of 92 is “0”, the threshold value 83 or the threshold value 93 is “1”.

  In addition, when the threshold value of the elasticity value or the luminance value is set in step S304, the area mask creating unit 62 sets the value of the first area mask (“0” or “1”) and the second area mask. A value (“0” or “1”) is multiplied to generate a third region mask (step S306). For example, as shown in FIG. 7 (d), the area mask creating unit 62 multiplies the value of the first area mask and the value of the second area mask, and the low reliability area 110 is “0”. 84 or area 92 is “0”, and the third area mask is set so that the area 200 corresponding to the elastic value or luminance value corresponding to the highly reliable area and exceeding the threshold 83 or 93 is “1”. Generate. This generates a third region mask for removing the region 84 (or region 92) corresponding to the low reliability region 110 and the sclerotic tissue 74 (or tumor tissue 72).

  The area calculation unit 64 extracts the elasticity information of the area 100 or the area 200 from which the area corresponding to the set condition (threshold value) is removed according to the first area mask or the third area mask (step S208). The area calculation unit 64 extracts the elasticity information of the area 100 or the area 200 by multiplying the elasticity value by the value (“0” or “1”) of the first area mask or the third area mask.

  The compression information generation unit 52 generates compression information on the part of the subject 10 except for the region corresponding to the set threshold value (step S210). For example, the compression information generation unit 52 indexes the compression information based on the average or deviation of elasticity information (for example, strain) extracted by the region calculation unit 64. Thus, by generating compression information excluding the region 84 (or region 92) corresponding to the low-reliability region 110 and the sclerotic tissue 74 (or tumor tissue 72), the S / N of the ultrasonic signal is reduced and It is possible to obtain the same compression information as when the normal tissue 70 is compressed without being affected by the state of the observation site.

  Based on the generated compression information, the compression information generation unit 52 converts an index (average, deviation, etc.) indicating the compression state of the observation site into visual information such as a graph, a histogram, and an index meter, and then combines the images. The image synthesizing unit 26 synthesizes the visual information converted by the compression information generating unit 52 into the synthesized image of the tomographic image and the elasticity image, and displays the synthesized image on the image display unit 28 (step S212). For example, as shown in FIG. 7 (e), the compression information generation unit 52 converts an index (for example, an average of elasticity values) representing the compression state of the observation site into a time series graph 106.

  In addition, in step S205 in FIG. 6, when the region exclusion function based on elasticity information or luminance information is turned on, the region corresponding to the hardened tissue 74 (or tumor tissue 72) is removed, and compression information is generated. The ultrasonic imaging apparatus 1 of the present embodiment includes a tissue identification unit (not shown) that identifies a specific tissue of the subject 10, and the compression information generation unit 52 excludes an area corresponding to the specific tissue, The compression information on the part of the subject 10 may be generated. For example, the tissue identification unit identifies the sclerosing tissue 74 (or tumor tissue 72), and the compression information generation unit 52 excludes the region corresponding to the sclerosing tissue 74 (or tumor tissue 72). The compression information may be generated.

  Further, in step S306 of FIG. 6, the value of the first region mask is multiplied by the value of the second region mask to generate a third region mask, and the low reliability region 110 and the hardened tissue 74 (or tumor tissue) 72), the compression information is generated by removing the region 84 (or the region 92) corresponding to 72). The first compression information and the second compression information are respectively generated by the first region mask and the second region mask. And may be generated respectively. That is, the compression information generation unit 52 generates the first compression information of the part of the subject 10 except the region corresponding to the matching degree threshold, and the region corresponding to at least one threshold of the elastic value and the luminance value The second compression information of the part of the subject 10 may be generated.

  Similarly, first compression information based on a threshold value of elasticity value and second compression information based on a threshold value of luminance value may be respectively generated. That is, the threshold value setting unit 50 sets the elasticity value and the threshold value of the luminance value based on the elasticity information and the luminance information, and the compression information generation unit 52 excludes the region corresponding to the elasticity value threshold value, and the subject 10 The first compression information on the part 10 may be generated, and the second compression information on the part of the subject 10 may be generated excluding the region corresponding to the threshold value of the luminance value.

  FIG. 8 is a diagram showing that first compression information based on a threshold value of elasticity value and second compression information based on a threshold value of luminance value are generated. As illustrated in FIG. 8A, the threshold setting unit 50 generates a histogram 81 of elasticity information values (elasticity values), and generates a distribution of elasticity values (for example, strain values) of hard tissue and soft tissue. . Further, as shown in FIG. 8 (b), the threshold setting unit 50 generates a histogram 91 of luminance information values (luminance values), and the luminance values of the hard tissue (low luminance) and the soft tissue (high luminance). Generate a distribution. The area mask creating unit 62 creates a first area mask for excluding an area (area 84 in FIG. 4) corresponding to the set condition (threshold 83), and corresponds to the set condition (threshold 93). Second area masks for excluding the area (area 92 in FIG. 5) are respectively created. The compression information generation unit 52 generates the first compression information 111 of the region of the subject 10 except for the region corresponding to the elastic value threshold (region 84 in FIG. 4) by using the first region mask. Then, by using the second area mask, the second compression information 112 of the site of the subject 10 is generated except for the area corresponding to the threshold value of the luminance value (area 92 in FIG. 5).

  Further, the compression information generation unit 52 selects a compression information acquisition region for acquiring compression information at the site of the subject 10, and generates compression information by excluding the region corresponding to the threshold from the selected compression information acquisition region. May be. FIG. 9 is a diagram illustrating the generation of compression information by selecting a compression information acquisition region. As shown in FIG. 9 (a), in the combined image of the tomographic image and the elastic image, the normal tissue 70 and the tumor tissue 72 in the tomographic image are displayed on the image display unit 28 based on the luminance information, and the normal tissue 70 in the elastic image is displayed. The hardened tissue 74 is displayed on the image display unit 28 based on the elasticity information. As shown in FIG. 9 (b), the condition setting unit 60 presets the compression information acquisition region 122 in the depth direction. When pressure is applied from the body surface of the subject 10, the internal stress attenuates as the depth increases. Further, since a large amount of fat capable of obtaining a stable strain is present on the body surface of the subject 10, stable strain can be obtained closer to the body surface of the subject 10 (the shallower in the depth direction). In consideration of these characteristics, the condition setting unit 60 sets the compression information acquisition region 122 near the body surface (shallow part) of the subject 10, and the compression information generation unit 52 selects the compression information acquisition region 122. By generating the compression information by excluding the region 120 corresponding to the threshold value from the compression information acquisition region 122, it is possible to generate the compression information using fat capable of obtaining a stable distortion as a reference. Further, as shown in FIG. 9 (c), the compression information generation unit 52 selects the compression information acquisition region 126 in a deep part where the abnormal tissue (hardened tissue 74) does not exist, and corresponds to the threshold value from the compression information acquisition region 126. By generating the compression information excluding the region 120, the compression information when the normal tissue 70 is compressed can be obtained. As described above, the compression information generation unit 52 can select a compression information acquisition region from the shallow compression information acquisition region 122, the intermediate compression information acquisition region 124, and the deep compression information acquisition region 126. In addition to the depth direction, the compression information acquisition area may be divided and set in the body surface direction of the subject 10 (left and right direction in FIG. 9 (c)), and the compression information acquisition area is divided and set. May be.

  Also, in FIGS. 4, 5, and 8, in order to obtain the compression information excluding the sclerosing tissue 74 (or tumor tissue 72), the compression information generating unit 52 has elasticity on the hardening side and the low luminance side from the threshold value. The compression information is generated except for the region corresponding to the value, but in order to acquire the compression information excluding the softened tissue (or liquid tissue), the compression information generating unit 52 has elasticity on the softening side and the high luminance side from the threshold value. The compression information may be generated excluding the area corresponding to the value.

  Further, the image display unit 28 displays at least one ultrasonic image of the tomographic image and the elastic image, and displays the region mark indicating the region to be removed (for example, the region 84, the region 92, and the low reliability region 110). You may display on an ultrasonic image. Based on the threshold set by the threshold setting unit 50, the image combining unit 26 combines the area mark with the ultrasonic image. The area mark includes the color attached to the area to be removed, the line and color attached to the boundary of the area to be removed, and the blinking or color change of the area (or boundary) to be removed.

  In addition, the ultrasonic imaging apparatus 1 of the present embodiment may include the operation unit 40 that adjusts the threshold value, and the image display unit 28 may change and display the area mark in accordance with the change of the threshold value. In accordance with the change of the threshold set by the threshold setting unit 50 via the operation unit 40, the image synthesis unit 26 changes the area mark and synthesizes it with the ultrasonic image. For example, the size of the area mark changes according to the change in the threshold value. Further, the color of the region mark changes according to the position of the threshold value in the histogram.

  Further, the threshold value setting unit 50 sets a plurality of at least one threshold value of the elasticity value and the luminance value, and the compression information generation unit 52 sets weighting factors in a plurality of areas corresponding to the set plurality of threshold values, and weights The compression information of the part of the subject 10 may be generated by performing weighted averaging using a coefficient. For example, as shown in FIG. 10 (a), the threshold value setting unit 50 sets a plurality of elastic value threshold values (threshold values 83 and 183), and the compression information generating unit 52 sets the plurality of threshold values 83 and 183 to be set. The compression information of the part of the subject 10 may be generated by setting weighting factors A, B, and C in a plurality of corresponding regions and performing weighted averaging using the weighting factors A, B, and C. Further, as shown in FIG. 10 (b), the threshold setting unit 50 sets a plurality of elastic value thresholds (thresholds 93 and 193), and the compression information generating unit 52 sets the plurality of thresholds 93 and 193 to be set. The compression information of the part of the subject 10 may be generated by setting weighting factors D, E, and F in a plurality of corresponding regions and performing weighted averaging using the weighting factors D, E, and F.

  Further, the threshold setting unit 50 sets a plurality of matching degree thresholds, and the compression information generating unit 52 sets weighting factors in a plurality of regions corresponding to the plurality of set thresholds, and uses the weighting factors to perform weighted averaging. By doing so, the compression information of the part of the subject 10 may be generated. In this way, by performing weighted averaging according to a plurality of regions corresponding to a plurality of threshold values, it is possible to obtain compression information that takes into account the characteristics (hardness / softness, brightness level, reliability, etc.) of each region. If the weighting factor is “0”, the area corresponding to the threshold value is removed and the compression information is generated.

  The ultrasonic imaging apparatus and the ultrasonic image display method according to the present invention are not affected by the state of the observation region, even when an abnormal tissue having a hardness different from that of the normal tissue is present in the observation region. It is possible to obtain the same compression information as when pressure is applied to the. Further, the present invention is similar to the case where compression is applied to normal tissue without being affected by the decrease in S / N even when a matching error occurs due to the decrease in S / N of the ultrasonic signal. Compression information can be obtained, and is useful as an ultrasonic imaging apparatus and an ultrasonic image display method for displaying a tomographic image in a subject using ultrasonic waves.

1 Ultrasonic imaging device
12 Ultrasonic probe
14 Transmitter
18 Ultrasonic transmission / reception controller
20 Receiver
22 Phased adder
24 Tomographic image component
26 Image composition part
28 Image display
30 RF signal frame data selector
32 Displacement measurement unit
34 Elasticity information calculation section
36 Elastic image component
40 Operation unit
42 Control unit
50 Threshold setting section
52 Compression information generator
60 Condition setting section
62 Area mask creation part
64 area operation part
66 Time information storage

Claims (15)

An elasticity information calculation unit for calculating elasticity information of the part of the subject from the ultrasound data of the subject;
Based on at least one of the elasticity information and the luminance information of the ultrasonic data, a threshold setting unit that sets at least one threshold of the elasticity value and the luminance value;
A compression information generating unit that generates compression information that is an index representing the compression state of the region of the subject except for an area where the elasticity value or the luminance value is above, above, below, or below the set threshold. An ultrasonic imaging apparatus comprising: In the search region of the part of the subject, a matching information calculation unit that calculates matching information of a search unit from the ultrasound data,
The elasticity information calculation unit calculates elasticity information of the region of the subject based on the matching information,
The threshold value setting unit sets a threshold value of the matching degree of the search unit based on the matching information,
The compression information generation unit generates the compression information of the region of the subject except for a region where the degree of matching is above, above, below, or below the set threshold value. The ultrasonic imaging apparatus according to 1. The threshold setting unit sets at least one threshold value of an elastic value and a luminance value based on at least one of the elasticity information and luminance information of the ultrasonic data,
The compression information generation unit generates the compression information of the region of the subject except for a region where the elasticity value or the luminance value is above, above, below, or below the set threshold value. Item 5. The ultrasonic imaging apparatus according to Item 2. A tissue identification unit for identifying a specific tissue of a subject;
3. The ultrasonic imaging apparatus according to claim 2, wherein the compression information generation unit generates compression information of a part of the subject excluding a region corresponding to the specific tissue. The threshold setting unit sets a threshold value of the elasticity value and the brightness value based on the elasticity information and the brightness information,
The compression information generation unit generates first compression information of the region of the subject except for a region where the elasticity value is above, above, below, or below the elasticity value threshold, and the luminance value threshold 2. The ultrasonic imaging apparatus according to claim 1, wherein the second compression information of the part of the subject is generated except for a region where the luminance value is above or above or below or below . The compression information generation unit generates the first compression information of the region of the subject except the region where the value of the matching degree is above, above, below or below the threshold value of the matching degree, and the elasticity value 4. The ultrasonic imaging apparatus according to claim 3, wherein second compression information of the part of the subject is generated except for a region corresponding to at least one threshold value of the luminance value. The compression information generation unit selects a compression information acquisition region for acquiring the compression information at the site of the subject, and an elastic value or a luminance value is higher than or equal to the threshold value from the selected compression information acquisition region. The ultrasonic imaging apparatus according to claim 1, wherein the compression information is generated except for the above, below, or the following areas.   The threshold value setting unit generates at least one histogram of the elasticity value and the luminance value at the measurement point of the ultrasonic data, and sets the threshold value based on the histogram. Ultrasonic imaging device. 3. The ultrasonic imaging apparatus according to claim 2, wherein the threshold value setting unit generates a histogram of the matching degree in the search unit and sets the threshold value based on the histogram.   The ultrasonic display according to claim 1, further comprising an image display unit that displays at least one ultrasonic image of a tomographic image and an elastic image, and displays a region mark indicating the region to be removed on the ultrasonic image. Sound imaging device. An operation unit for adjusting the threshold value;
11. The ultrasonic imaging apparatus according to claim 10, wherein the image display unit changes and displays the region mark in accordance with the change in the threshold value.   11. The ultrasonic imaging apparatus according to claim 10, wherein the image display unit changes and displays the region mark in accordance with the change in the threshold value. The threshold setting unit sets a plurality of threshold values of at least one of the elasticity value and the luminance value,
The compression information generation unit sets a weighting factor in a plurality of regions whose elasticity value or luminance value is above, above, below, or below than the set thresholds, and performs weighted averaging using the weighting factor. 2. The ultrasonic imaging apparatus according to claim 1, wherein the compression information of the part of the subject is generated by: The threshold setting unit sets a plurality of thresholds of the matching degree,
The compression information generation unit sets a weighting factor in a plurality of regions where the degree of matching is above, above, below, or below from the set thresholds, and performs weighted averaging using the weighting factor. 3. The ultrasonic imaging apparatus according to claim 2, wherein compression information on a part of the subject is generated. Calculate elasticity information of the part of the subject from the ultrasound data of the subject,
Based on at least one of the elasticity information and the luminance information of the ultrasonic data, set at least one threshold value of the elasticity value and the luminance value,
Excluding a region where the elasticity value or luminance value is above, above, below, or below the set threshold value, compression information that is an index indicating the compression state of the part of the subject is generated. Sound image display method.

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