JP5449896B2 - Ultrasonic diagnostic equipment - Google Patents

Description

  The present invention relates to an ultrasonic diagnostic apparatus, and more particularly to an ultrasonic diagnostic apparatus that displays an elastic image representing the hardness or softness of a living tissue.

  For example, Patent Literature 1 discloses an ultrasonic diagnostic apparatus that synthesizes and displays a normal B-mode image and an elastic image representing the hardness or softness of a living tissue. In this type of ultrasonic diagnostic apparatus, the elasticity image is created as follows. First, ultrasonic waves are transmitted to and received from a living tissue while repeating compression and relaxation from the body surface with an ultrasonic probe, and an echo signal is acquired. Then, based on the obtained echo signal, a physical quantity related to the elasticity of the living tissue is calculated, and the physical quantity is converted into hue information to create a color elastic image. Incidentally, as a physical quantity related to the elasticity of the living tissue, for example, a displacement due to deformation of the living tissue (hereinafter simply referred to as “displacement”) is calculated.

  Explaining a little more about an example of the calculation method of the physical quantity, first, correlation windows having a width corresponding to a predetermined number of data are respectively set in two echo signals on the same sound ray belonging to two temporally different frames. The physical quantity is calculated by performing a correlation operation between the windows. For example, in Patent Document 2, a correlation shift between correlation windows is performed to calculate a waveform shift between both echo signals, and the waveform shift is regarded as a displacement.

  The correlation windows are sequentially set in the sound ray direction, and a correlation calculation is performed for each correlation window to calculate the physical quantity. Here, in Patent Document 2, of the two echo signals belonging to different frames, the echo signal belonging to one frame is moved by a certain amount from the correlation window in which the correlation calculation is performed, and the next post-correlation window Set up. On the other hand, for echo signals belonging to other frames, the amount of movement from the correlation window is determined using the physical quantity obtained by the correlation calculation for the correlation window, and the post-correlation window is set. (See paragraph [0044] of Patent Document 2). Thus, the higher the degree of matching between the correlation windows set for echo signals belonging to two frames, the higher the correlation coefficient in the correlation calculation, and the calculated value obtained more accurately reflects the elasticity of living tissue. Calculated value.

JP-A-2005-118152 Japanese Patent Laid-Open No. 2008-126079

  By the way, when the quality of the echo signal is poor, the degree of matching between the correlation windows is low and the correlation calculation has a low correlation coefficient, and a physical quantity that accurately reflects the elasticity of the living tissue cannot be obtained. For example, when there is a locally hard portion in the living tissue due to calcification or the like, the hard portion may be displaced laterally due to compression by the ultrasonic probe and relaxation thereof. In this case, since the signal waveform of the echo signal at the shifted portion is different in each of the two frames, the degree of matching between the correlation windows for performing the correlation calculation is low, and the correlation coefficient is low. Also, when the correlation calculation is performed on the correlation window set in the portion where the signal intensity is low, the degree of matching is reduced and the correlation coefficient is reduced as described above. Thus, when the quality of the echo signal is poor, the correlation coefficient in the correlation calculation is low, and the calculated physical quantity does not accurately reflect the elasticity of the living tissue.

  Further, when the degree of matching of the correlation window is low and the physical quantity obtained by the correlation calculation does not accurately reflect the elasticity of the living tissue, the post-correlation window that is set next based on the physical quantity The correlation coefficient of the correlation calculation also becomes low, and the physical quantity obtained as a result of the calculation does not accurately reflect the elasticity of the living tissue. Therefore, when there is a correlation window on which a physical quantity that accurately reflects the elasticity of living tissue cannot be obtained on a certain sound ray, depending on the signal waveform, the degree of matching between post-correlation windows set after this correlation window is low. The condition continues and linear artifacts may appear in the elastic image.

  The problem to be solved by the present invention is to provide an ultrasonic diagnostic apparatus capable of obtaining an elastic image that more accurately reflects the elasticity of a living tissue than before.

  In addition, another problem to be solved by the present invention is that it is possible to obtain an elastic image that more accurately reflects the elasticity of living tissue than before by preventing the appearance of linear artifacts in the elastic image. An ultrasonic diagnostic apparatus is provided.

  The present invention has been made to solve the above-mentioned problems. The invention of the first aspect is an echo signal obtained by transmitting / receiving ultrasonic waves to / from a living tissue, and includes two temporally different signals. Based on the physical quantity, a physical quantity calculation unit that sets a correlation window to two echo signals on the same sound ray belonging to the frame, performs a correlation calculation between the correlation windows, and calculates a physical quantity related to the elasticity of the living tissue, An elasticity image data creation unit that creates elasticity image data of a living tissue for each correlation window, and the elasticity image data creation unit generates the elasticity image data for the correlation window on one sound ray. Of the elastic image data according to the correlation calculation of the other sound ray correlation window on another sound ray different from the one sound ray. An ultrasonic diagnostic apparatus characterized by performing the formation.

  According to a second aspect of the invention, in the first aspect of the invention, in creating elastic image data for the correlation window, the calculated value obtained by the correlation calculation of the correlation window and the correlation of the other sound ray correlation window A selection unit that selects a calculation value suitable for creation of elasticity image data for the correlation window from the calculation values obtained by the calculation is provided, and the elasticity image data creation unit is a calculation selected by the selection unit. The ultrasonic diagnostic apparatus is characterized in that elasticity image data for the correlation window is created based on a value.

  According to a third aspect of the invention, in the invention of the second aspect, the physical quantity calculation unit is set next to the correlation window in an echo signal on one sound ray belonging to one of the two frames. In the ultrasonic diagnostic apparatus, a post-correlation window is set based on a calculated value selected by the selection unit.

  According to a fourth aspect of the present invention, in the second or third aspect of the invention, the selection unit selects a calculation value suitable for creating elastic image data for the correlation window, and selects the correlation obtained by the calculation value. The ultrasonic diagnostic apparatus is characterized in that it is performed based on whether a correlation coefficient of calculation or the calculated value is within a predetermined range.

  According to a fifth aspect of the present invention, in the invention according to any one of the second to fourth aspects, when the correlation coefficient in the correlation calculation of the correlation window exceeds a predetermined threshold value, the selection unit correlates the correlation window. When the calculated value obtained by the calculation is selected as a calculated value suitable for creating elastic image data for the correlation window, while the correlation coefficient in the correlation calculation of the correlation window is equal to or less than the predetermined threshold, A calculated value obtained by the correlation calculation of the other sound ray correlation window, the calculated value obtained by the correlation calculation of the correlation coefficient exceeding the correlation coefficient in the correlation calculation of the correlation window, or a calculated value within a predetermined range Is selected as a calculated value suitable for creation of elasticity image data for the correlation window.

  The invention according to a sixth aspect is the invention according to any one of the second to fourth aspects, wherein the selection unit includes a correlation coefficient in the correlation calculation of the correlation window and a phase relationship in the correlation calculation of the other sound ray correlation window. The ultrasonic diagnostic apparatus is characterized in that a calculated value obtained by a correlation calculation having the highest correlation coefficient is selected as a calculated value suitable for creation of elastic image data for the correlation window.

  The invention according to a seventh aspect is the invention according to any one of the second to fourth aspects, wherein, when the calculated value obtained by the correlation calculation of the correlation window is within a predetermined range, the selection unit The calculation value obtained by the correlation calculation of the window is selected as a calculation value suitable for creating elastic image data for the correlation window, while the calculation value obtained by the correlation calculation of the correlation window is outside a predetermined range. In some cases, the calculated value obtained by the correlation calculation of the other sound ray correlation window, the calculated value obtained by the correlation calculation of the correlation coefficient exceeding the correlation coefficient in the correlation calculation of the correlation window, or the predetermined value In the ultrasonic diagnostic apparatus, a calculated value within a range is selected as a calculated value suitable for creation of elasticity image data for the correlation window.

  The invention according to an eighth aspect is the invention according to any one of the second to fourth aspects, wherein the selection unit obtains a calculation obtained by correlation calculation of the other sound ray correlation window for a plurality of the other sound rays. Based on the distribution of the values, it is determined whether or not the calculated value obtained by the correlation calculation of the correlation window is suitable for generating elastic image data for the correlation window, and for generating elastic image data for the correlation window If it is determined that it is suitable, the calculated value obtained by the correlation calculation of the correlation window is selected as the calculated value suitable for creating elastic image data for the correlation window, while the elasticity for the correlation window is selected. If it is determined that the image data is not suitable for creation, it is a calculated value obtained by the correlation calculation of any one of the other sound ray correlation windows, and the correlation window A calculation value obtained by correlation calculation of a correlation coefficient exceeding a correlation coefficient in dough correlation calculation or a calculation value within the predetermined range is selected as a calculation value suitable for creation of elastic image data for the correlation window. This is an ultrasonic diagnostic apparatus.

  According to a ninth aspect of the invention, in the first aspect of the invention, in generating elastic image data for the correlation window, the calculated value obtained by the correlation calculation of the correlation window and the correlation of the other sound ray correlation window An average calculation unit that performs an average calculation with the calculated value obtained by the calculation, and the elasticity image data creation unit creates elasticity image data for the correlation window based on the average value obtained by the average calculation unit It is an ultrasonic diagnostic apparatus characterized by performing.

  According to a tenth aspect of the present invention, in the ninth aspect of the invention, the average calculation unit is configured to calculate a correlation calculation value of the other sound ray correlation window for the plurality of other sound rays and a correlation between the correlation windows. An ultrasonic diagnostic apparatus that performs an average operation on a calculated value obtained by an operation.

  According to an eleventh aspect of the invention, in the tenth aspect of the invention, the average calculation includes an error determination unit that determines whether the calculated value obtained by the correlation calculation of the other sound ray correlation window is an error. The unit is the ultrasonic diagnostic apparatus characterized in that the average calculation is performed except for the calculated error value.

  According to a twelfth aspect of the present invention, in the first aspect of the invention, an error determination unit that determines whether there is an error in the calculated value obtained by the correlation calculation of the correlation window, and an elastic image of the correlation window In creating the data, when the error determination unit determines that the calculated value obtained by the correlation calculation of the correlation window is an error, the correlation calculation of the other sound ray correlation window for the plurality of other sound rays is performed. An average calculation unit that performs an average calculation of the obtained calculated values, and the elastic image data generation unit generates elastic image data for the correlation window based on the average value obtained by the average calculation unit It is an ultrasonic diagnostic apparatus characterized by performing.

  The invention according to a thirteenth aspect is the invention according to any one of the eleventh and twelfth aspects, wherein the error determination unit determines whether there is an error based on a correlation coefficient in a correlation calculation in which a calculated value to be determined is obtained. It is an ultrasonic diagnostic apparatus characterized by determining.

  The invention of the fourteenth aspect is characterized in that, in the inventions of the eleventh and twelfth aspects, the error determination unit determines an error when the calculated value to be determined is not within a predetermined range set in advance. This is an ultrasonic diagnostic apparatus.

  In a fifteenth aspect of the invention according to the eleventh and twelfth aspects of the invention, the error determination unit determines whether or not the calculated value of the determination target is an error based on a distribution of calculated values of other determination targets. This is an ultrasonic diagnostic apparatus.

  The invention of a sixteenth aspect is the invention of any one of the ninth to fifteenth aspects, wherein the physical quantity calculation unit is configured to use the correlation window in an echo signal on one sound ray belonging to one of the two frames. The ultrasonic diagnostic apparatus is characterized in that a post-correlation window set next to is set based on the average value obtained by the average calculation unit.

  According to a seventeenth aspect of the present invention, in the invention according to any one of the ninth to sixteenth aspects, the average calculation unit performs weighting according to a correlation coefficient with respect to a calculated value that is a target of the average calculation. Is an ultrasonic diagnostic apparatus.

  An eighteenth aspect of the invention is the ultrasonic wave according to any one of the first to seventeenth aspects, wherein the other sound ray correlation window is positioned at the same depth in the biological tissue and the correlation window. It is a diagnostic device.

  According to the present invention, the elastic image data creating unit generates the elastic image data for the correlation window on the one sound ray according to the correlation calculation of the correlation window and the correlation calculation of the other sound ray correlation window. Create elastic image data. Therefore, even when the calculated value obtained as a result of the correlation calculation in the correlation window does not accurately reflect the elasticity of the biological tissue, the calculated value obtained as a result of the correlation calculation in the other sound ray correlation window is determined as the biological tissue. The elasticity image data for the correlation window on the one sound ray can be data that more accurately reflects the elasticity of the living tissue than in the past. As a result, an elasticity image reflecting the elasticity of the living tissue more accurately than before can be obtained for the correlation window.

  Further, according to the present invention, the selection unit obtains the calculated value obtained by the correlation calculation of the correlation window and the correlation calculation of the other sound ray correlation window when creating the elasticity image data for the correlation window. From the calculated values, a calculation value suitable for creation of elasticity image data for the correlation window is selected, and the elasticity image data creation unit selects elasticity image data for the correlation window based on the selected calculation value. Create. Therefore, even if the calculated value obtained by the correlation calculation of the correlation window does not accurately reflect the elasticity of the biological tissue, the calculated value obtained by the correlation calculation of the other sound ray correlation window is the elasticity of the biological tissue. Is more accurately reflected, the calculated value of the correlation calculation of the other sound ray correlation window is selected as a calculated value suitable for creating elastic image data for the correlation window. As a result, an elasticity image reflecting the elasticity of the living tissue more accurately than before can be obtained for the correlation window.

  In addition, in an echo signal on one sound ray belonging to one of the two frames, when the post-correlation window is set next to the correlation window, a calculated value obtained as a result of the correlation calculation of the correlation window is Even if it does not accurately reflect the elasticity of the living tissue, by setting the post-correlation window based on the calculated value selected by the selection unit, between the post-correlation windows in two frames The post-correlation window in one frame can be set so that the degree of matching is higher than before. As described above, it is possible to suppress the appearance of linear artifacts in the elastic image, and it is possible to obtain an elastic image that more accurately reflects the elasticity of the living tissue than in the past.

  Further, according to the present invention, the average calculation unit performs an average calculation of the calculated value obtained by the correlation calculation of the correlation window and the calculated value obtained by the correlation calculation of the other sound ray correlation window, The elastic image data creation unit creates elastic image data for the correlation window based on the average value obtained by the average calculation unit. Therefore, even when the calculated value obtained by the correlation calculation of the correlation window does not accurately reflect the elasticity of the biological tissue, the calculated value obtained by the correlation calculation of the other sound ray correlation window is the elasticity of the biological tissue. Can be made into the data which reflected the elasticity of the biological tissue more correctly than before. As a result, an elasticity image reflecting the elasticity of the living tissue more accurately than before can be obtained for the correlation window.

  Further, according to the present invention, when creating the elastic image data for the correlation window, when the error determination unit determines that the calculated value obtained by the correlation calculation of the correlation window is an error, a plurality of the other An average calculation of the calculated values obtained by the correlation calculation of the other sound ray correlation window with respect to the sound ray is performed, and the elasticity image data creation unit is configured to perform the correlation window based on the average value obtained by the average calculation unit. Elastic image data for is created. Therefore, even when the calculated value obtained by the correlation calculation of the correlation window does not accurately reflect the elasticity of the biological tissue, the calculated value obtained by the correlation calculation of the other sound ray correlation window is the elasticity of the biological tissue. Can be made into the data which reflected the elasticity of the biological tissue more correctly than before. As a result, an elasticity image reflecting the elasticity of the living tissue more accurately than before can be obtained for the correlation window.

  In addition, in an echo signal on one sound ray belonging to one of the two frames, when the post-correlation window is set next to the correlation window, a calculated value obtained as a result of the correlation calculation of the correlation window is Even if the elasticity of the living tissue is not accurately reflected, by setting the post-correlation window based on the average value obtained by the average calculation unit, matching between the post-correlation windows in two frames The post-correlation window in one frame can be set so that the degree is higher than in the past. As described above, it is possible to suppress the appearance of linear artifacts in the elastic image, and it is possible to obtain an elastic image that more accurately reflects the elasticity of the living tissue than in the past.

1 is a block diagram showing a schematic configuration of an embodiment of an ultrasonic diagnostic apparatus according to the present invention. It is a block diagram which shows the structure of the elasticity image process part of the ultrasonic diagnosing device shown in FIG. It is a figure which shows the ultrasonic image displayed on the display part. It is a figure for demonstrating the setting of the correlation window at the time of creating elasticity image data. It is explanatory drawing which shows the state in which the other sound ray correlation window was set. It is explanatory drawing which shows the state in which the other sound ray correlation window was set. It is a figure for demonstrating the setting of a correlation window. It is explanatory drawing which shows the state in which the other sound ray correlation window was set. It is a block diagram which shows the structure of the elastic image process part in 2nd embodiment. It is a block diagram which shows the structure of the elasticity image process part in the modification of 2nd embodiment.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
(First embodiment)
First, a first embodiment will be described with reference to FIGS. An ultrasonic diagnostic apparatus 1 shown in FIG. 1 includes an ultrasonic probe 2, a transmission / reception unit 3, a B-mode image processing unit 4, an elastic image processing unit 5, a synthesis unit 6, and a display unit 7, and further includes a control unit 8 and an operation unit. 9 is provided.

  The ultrasonic probe 2 transmits an ultrasonic wave to a living tissue and receives an echo thereof. An elastic image is created as described below based on echo signals acquired by transmitting and receiving ultrasonic waves while repeating compression and relaxation while the ultrasonic probe 2 is in contact with the surface of the living tissue.

  The transmission / reception unit 3 drives the ultrasonic probe 2 under a predetermined scanning condition to perform ultrasonic scanning for each sound ray. Further, the echo signal received by the ultrasonic probe 2 is subjected to signal processing such as phasing addition processing.

  Incidentally, the transmission / reception unit 3 separately performs scanning for creating a B-mode image and scanning for creating an elastic image. As scanning for creating an elastic image, scanning is performed twice on the same sound ray in a region where an elastic image is created in the subject.

  The B-mode image processing unit 4 performs B-mode processing such as logarithmic compression processing and envelope detection processing on the echo signal output from the transmission / reception unit 3 to create B-mode image data.

  The elastic image processing unit 5 creates elastic image data based on the echo signal output from the transmission / reception unit 3. As shown in FIG. 2, the elastic image processing unit 5 includes a physical quantity calculation unit 51 and an elastic image data creation unit 52, and further includes a selection unit 53.

  The physical quantity calculation unit 51 calculates a displacement (hereinafter, simply referred to as “displacement”) due to deformation of each part in the biological tissue caused by the compression and relaxation by the ultrasonic probe 2 as a physical quantity related to the elasticity of each part in the biological tissue. To do. The physical quantity calculation unit 51 calculates a displacement based on two echo signals on the same sound ray belonging to two temporally different frames (i) and (ii) as shown in FIG. Details will be described later. The physical quantity calculator 51 is an example of an embodiment of a physical quantity calculator in the present invention.

  The elasticity image data creation unit 52 converts the displacement calculated by the physical quantity calculation unit 51 into hue information, and creates elasticity image data in a region where an elasticity image is created. The elastic image data creation unit 52 is an example of an embodiment of the elastic image data creation unit in the present invention.

  In this example, a region of interest (ROI) R is set on the B-mode image BG displayed on the display unit 7 as shown in FIG. Is created. However, the present invention is not limited to the case where the elastic image is generated for a part of the B-mode image BG as described above, and the elastic image data may be generated for the entire B-mode image BG.

  In generating elastic image data for a correlation window on one sound ray, the selection unit 55 calculates a correlation between the displacement of the correlation window and another sound ray correlation window on another sound ray different from the one sound ray. From the displacements obtained in step 1, a displacement suitable for creating elastic image data for the correlation window is selected. Details will be described later. The selection unit 55 is an example of an embodiment of a selection unit in the present invention.

  The B-mode image data created by the B-mode image processing unit 4 and the elasticity image data created by the elasticity image processing unit 5 are synthesized by the synthesis unit 6. Specifically, the synthesizing unit 6 adds the B-mode image data for one frame and the elastic image data, and creates ultrasonic image data for one frame to be displayed on the display unit 7. The ultrasonic image data obtained by the combining unit 6 is displayed on the display unit 7 as an ultrasonic image G in which a monochrome B-mode image BG and a color elastic image EG are combined as shown in FIG. Is done. In this example, the elastic image EG is displayed translucently in the region of interest R (with the background B-mode image transparent).

  The control unit 8 is constituted by a CPU (Central Processing Unit), reads a control program stored in a storage unit (not shown), and executes functions in each unit of the ultrasonic diagnostic apparatus 1. The operation unit 9 includes a keyboard and a pointing device (not shown) for the operator to input instructions and information.

  Now, the operation of the ultrasonic diagnostic apparatus 1 of this example will be described. First, the transmission / reception unit 3 transmits an ultrasonic wave from the ultrasonic probe 2 to a living tissue of a subject and acquires an echo signal thereof. At this time, the ultrasonic probe 2 transmits and receives ultrasonic waves while repeatedly pressing and relaxing the subject.

  When the echo signal is acquired, the B-mode image processing unit 4 creates B-mode image data based on the echo signal from the transmission / reception unit 3. The elastic image processing unit 5 creates elastic image data based on the echo signal from the transmission / reception unit 3. The B-mode image data and the elasticity image data are synthesized by the synthesis unit 6, and an ultrasonic image G in which the B-mode image BG and the elasticity image EG are synthesized is displayed on the display unit 7 as shown in FIG. Is done.

  The creation of elastic image data in the elastic image processing unit 5 will be described in detail. The frames (i) and (ii) shown in FIG. 4 are composed of echo signals acquired on a plurality of sound rays. In FIG. 4, five sound lines L1a, L1b, L1c, L1d, and L1e are shown as a part of the plurality of sound lines in the frame (i), and the sound lines L1a to L1e in the frame (ii) are shown. As sound lines corresponding to L1e, sound lines L2a, L2b, L2c, L2d, and L2e are shown. That is, the sound ray L1a and the sound ray L2a, the sound ray L1b and the sound ray L2b, the sound ray L1c and the sound ray L2c, the sound ray L1d and the sound ray L2d, the sound ray L1e and the sound ray. L2e corresponds to the same sound ray belonging to two different frames. In FIG. 4, R (i) and R (ii) indicate regions corresponding to the region of interest R.

  When creating elastic image data, the physical quantity calculation unit 51 sequentially creates a correlation window W1 on each sound ray from the upper end 100 to the lower end 101 of the region R (i) in the frame (i). The correlation window W2 is sequentially set on each sound ray from the upper end portion 100 to the lower end portion 101 of the region R (ii) in the frame (ii). Then, the elastic image data creation unit 52 creates an elastic image for the pixels corresponding to the correlation windows W1 and W2.

  Hereinafter, a case where elastic image data on the sound rays L1c and L2c is created will be described as an example. That is, here, the sound rays L1c and L2c are an example of an embodiment of one sound ray in the present invention, and other sound rays are an example of an embodiment of another sound ray in the present invention.

  The physical quantity calculator 51 sets correlation windows W1 and W2 for the echo signals S1 and S2 (not shown) on the sound rays L1c and L2c, respectively. Here, it is assumed that correlation windows W11c and W21c are set as the correlation windows W1 and W2.

The physical quantity calculator 51 performs a correlation operation between the correlation windows W11c and W21c, and calculates a displacement Xc. Next, the selection unit 53 sets the correlation coefficient Cc (0 <Cc <1, the same numerical range for other correlation coefficients described later) in the correlation calculation between the correlation windows W11c and W21c to a predetermined threshold C _TH. Compare with Incidentally, the threshold value C _TH is set in advance by the operator.

The selection unit 53, if the correlation coefficient Cc exceeds the threshold value C _TH, the displacement Xc of the correlation window W11c, select as the displacement suitable for the creation of the elastic image data for W21c. Here, “about the correlation windows W11c and W21c” means “about the pixels corresponding to the correlation windows W11c and W21c”.

On the other hand, when the correlation coefficient Cc is equal to or less than the threshold value _CTH , the selection unit 53, as shown in FIG. 5, the sound rays L1b, L2b which are sound rays adjacent to the left of the sound rays L1c, L2c. The correlation coefficient Cb in the correlation calculation between the correlation windows W11b and W21b set to is compared with the correlation coefficient Cc. However, at this time, the correlation coefficient Cb may be compared with the threshold value _CTH . Then, is higher than the correlation coefficient Cb is the correlation coefficient Cc or the threshold _{C TH,} the selecting section 53, the displacement Xb of the correlation windows W11c, suitable for creating elastic image data for W21c displacement Choose as. On the other hand, when the correlation coefficient Cb is equal to or less than the correlation coefficient Cc or the threshold value _CTH , the selection unit 53 is a sound ray right next to the sound rays L1c and L2c, as shown in FIG. the sound ray L1d, the correlation window W11d in L2d, compared with the correlation coefficient Cc or the threshold _{C TH} correlation coefficient Cd in the correlation calculation between W21d. Then, if the correlation coefficient Cd is higher than the correlation coefficient Cc or threshold _{C TH,} the correlation window W11d, W21d between obtained in the displacement Xd the correlation window W11c, the creation of the elastic image data for W21c Choose a suitable displacement. On the other hand, when the correlation coefficient Cd is equal to or less than the correlation coefficient Cc or the threshold value C _TH , the selection unit 53 repeats the above-described processing for further different sound rays, and the correlation coefficient Cc or the threshold value C _TH The displacement obtained by the correlation calculation having a higher correlation coefficient is selected as a displacement suitable for creating elastic image data for the correlation windows W11c and W21c.

Incidentally, a correlation window set to another sound ray different from the one sound ray for which the elastic image data is to be created is set as another sound ray correlation window. The correlation windows W11b and W21b and the correlation windows W11d and W21d are examples of other sound ray correlation windows. The correlation windows W11b and W21b and the correlation windows W11d and W21d are set at the same depth in the living tissue as the correlation windows W11c and W21c. The correlation windows W11b, W21b and the correlation windows W11d, W21d may be newly set and correlation calculation may be performed. However, the correlation windows W11b, L2d and the sound lines L1d, L2d have already been set. When W21b and the correlation windows W11d and W21d are set and correlation calculation is performed and elastic image data is generated, the correlation coefficients Cb and Cd in the correlation calculation at this time are used as the correlation coefficient Cc. Or you may compare with the said threshold value _CTH .

  The elastic image data creation unit 52 creates elastic image data for the correlation windows W11c and W21c based on the displacement selected by the selection unit 53.

  On the sound ray L1c, the correlation window W12c set next to the correlation window W11c is set by being moved by a predetermined number of data from the correlation window W11c as shown in FIG. . Here, the correlation window W12c is set by moving by the number of data corresponding to the window width of the correlation window W11c. The window width of the correlation window W12c is the same as the window width of the correlation window W11c. In the echo signal S1 on the sound ray L1c, correlation windows W1 having the same window width are sequentially set from the upper end portion 100 toward the lower end portion 101.

  On the sound ray L2c, the correlation window W22c set next to the correlation window W21c is based on the displacement window W21c and the correlation window W21c based on the displacement used for creating elastic image data for the correlation windows W11c and W21c. And the correlation window W22c is set. The correlation window W22c set in this way has a portion overlapping the correlation window W21c, and has a window width different from the window width of the correlation window W21c.

  According to the ultrasonic diagnostic apparatus 1 of the present example described above, in creating elastic image data for the correlation window on the one sound ray, the correlation calculation of this correlation window is different from the one sound ray. The elastic image data is created according to the correlation calculation of the other sound ray correlation window on the sound ray. For example, the displacement Xc obtained by the correlation calculation between the correlation windows W11c and W21c and the displacement obtained by the correlation calculation between the other sound ray correlation windows (the correlation windows W11b and W21b, the correlation windows W11d and W21d, etc.) Elastic image data for the correlation windows W11c and W21c is created based on the displacement selected by the selection unit 53. Therefore, even when the displacement Xc does not accurately reflect the elasticity of the living tissue, the displacement obtained by the correlation calculation between the other sound ray correlation windows more accurately reflects the elasticity of the living tissue. If there is, the displacement obtained by the correlation calculation between the other sound ray correlation windows is selected as a calculated value suitable for creating elastic image data for the correlation windows W11c and W21c, and elastic image data is created. Thereby, it is possible to obtain an elasticity image that accurately reflects the elasticity of the living tissue with respect to the correlation windows W11c and W21c.

  Further, a post-correlation window (such as the correlation window W22c) in which the correlation calculation is performed after the correlation window W21c in the frame (ii) is set based on the displacement selected by the selection unit 53. Thus, even when the displacement Xc obtained by the correlation calculation of the correlation windows W11c and W21c does not accurately reflect the elasticity of the living tissue, the degree of matching with the correlation window of the frame (i) is higher than that of the conventional case. A post-correlation window can be set in the frame (ii) to be higher. As described above, it is possible to suppress the appearance of linear artifacts in the elastic image EG, and it is possible to obtain an elastic image that more accurately reflects the elasticity of the living tissue than in the past.

Next, a modification of the first embodiment will be described. First, a first modification will be described with reference to FIG. In the first modified example, when the correlation coefficient Cc is equal to or less than the threshold value _CTH , as shown in FIG. 8, the physical quantity calculation unit 51 includes two adjacent left and right sound rays L1c and L2c. To the sound rays, that is, the sound rays L1a and L2a, the sound rays L1b and L2b, the sound rays L1d and L2d, the sound rays L1e and L2e, the correlation windows W11a and W21a, the correlation windows W11b and W21b, and the correlation windows W11d and W21d and correlation windows W11e and W21e are set. The physical quantity calculating unit 51 calculates the correlation between the correlation windows W11a and W21a, the correlation between the correlation windows W11b and W21b, the correlation between the correlation windows W11d and W21d, and the correlation between the correlation windows W11e and W21e. Calculations are performed to calculate displacements Xa, Xb, Xd, and Xe, respectively.

  Incidentally, if the displacements Xa, Xb, Xd, and Xe are already calculated when the elastic image data is already created for the other sound ray correlation window, the values calculated at this time may be used without calculating again. .

  Next, the selection unit 53 uses the correlation window W11c to calculate the displacement that is higher than the correlation coefficient Cc and obtained by the correlation calculation of the highest correlation coefficient among the displacements Xa, Xb, Xd, and Xe. , W21c is selected as a displacement suitable for creation of elastic image data.

However, the selection unit 53, when the correlation coefficient Cc is equal to or less than the threshold value C _TH, the displacement Xa, Xb, Xd, in Xe, either in the preset within a predetermined range The displacement may be selected as a displacement for setting the correlation window W21c. The predetermined range is set by an operator, for example, and is a range of displacement that the operator thinks is normally obtained.

  Next, a second modification will be described. In the second modification, the selection unit 53 selects the correlation among the correlation coefficient in the correlation calculation of the correlation window and the correlation coefficient in the correlation calculation of the other sound ray correlation window for generating elasticity image data. The calculated value obtained by the correlation calculation having the highest number is selected as a calculated value suitable for creating elastic image data for the correlation window. For example, the selection unit 53 uses the correlation coefficient Ca in the correlation calculation of the correlation windows W10a and W20a, the correlation coefficient Cb in the correlation calculation of the correlation windows W10b and W20b, and the correlation in the correlation calculation of the correlation windows W10c and W10c. The displacement obtained by the correlation calculation having the highest correlation coefficient among the number Cc, the correlation coefficient Cd in the correlation calculation of the correlation windows W10d and W20d, and the correlation coefficient Ce in the correlation calculation of the correlation windows W10e and W20e, The displacement is selected as a displacement suitable for creating elastic image data for the correlation windows W11c and W21c.

  Next, a third modification will be described. In the third modified example, when the displacement obtained by the correlation calculation of the correlation window for generating the elasticity image data is within a predetermined range, the selection unit 53 determines the displacement corresponding to the correlation window. Is selected as a displacement suitable for creation of elastic image data. On the other hand, when the displacement obtained by the correlation calculation of the correlation window is a displacement outside a predetermined range, the selection unit 53 is the displacement obtained by the correlation calculation of the other sound ray correlation window, and Is selected as a displacement suitable for generating elastic image data for the correlation window.

  For example, when creating elastic image data for the correlation windows W11c and W21c, if the displacement Xc obtained by the correlation calculation of the correlation windows W11c and W21c is within a predetermined range, the selection unit 53 selects this displacement Xc as a displacement suitable for creating elastic image data for the correlation windows W11c and W21c.

On the other hand, when the displacement Xc obtained by the correlation calculation of the correlation windows W11c and W21c is not within the predetermined range, the selection unit 53, for example, out of the displacements Xa, Xb, Xd, and Xe, Any displacement within the range is selected as a displacement suitable for creating elastic image data for the correlation windows W11c and W21c. In this case, of the displacements Xa, Xb, Xd, and Xe, any one of the displacements obtained by the correlation calculation in which the correlation coefficient exceeds the correlation coefficient Cc or the predetermined threshold value _CTH is arbitrarily selected. Also good. Moreover, you may select the displacement obtained by the correlation calculation with the highest correlation coefficient among the said displacement Xa, Xb, Xd, Xe.

  Incidentally, the predetermined range in this example is also a range of displacement that is set by an operator, for example, and that the operator thinks that the operator normally obtains.

  Next, a fourth modification will be described. Based on the distribution of displacement obtained by the correlation calculation of the other sound ray correlation window for the plurality of other sound rays, the selection unit 53 uses the calculated value obtained by the correlation calculation of the correlation window as the correlation window. It is determined whether or not it is suitable for creation of elastic image data. If the displacement obtained by the correlation calculation of the correlation window is not significantly different from the displacement distribution obtained by the correlation calculation of the other sound ray correlation window, the selection unit 53 The displacement obtained by the correlation calculation is selected as a displacement suitable for creating elastic image data for the correlation window. On the other hand, when the displacement obtained by the correlation calculation of the correlation window is significantly different from the displacement distribution obtained by the correlation calculation of the other sound ray correlation window, the selection unit 53 determines that the other sound ray correlation window The displacement obtained by the above correlation calculation and selected within the predetermined range is selected as a displacement suitable for creating elastic image data for the correlation window. Incidentally, the range determined to be significantly different is set in advance by the operator's judgment.

  For example, when generating elastic image data for the correlation windows W11c and W21c, the displacement Xc obtained by the correlation calculation of the correlation windows W11c and W21c is operated on the average value of the displacements Xa, Xb, Xd and Xe. If it is within a range of ± n% set by a person, the displacement Xc is selected as a displacement suitable for creating elastic image data for the correlation windows W11c and W21c.

On the other hand, when the displacement Xc does not fall within the range of ± n% set by the operator with respect to the average value of the displacements Xa, Xb, Xd, Xe, any of the displacements Xa, Xb, Xd, Xe A displacement within a predetermined range set in advance is selected as a correlation window suitable for setting the correlation window W21c. In this case, among the displacements Xa, Xb, Xd, and Xe, any one of the displacements obtained by the correlation calculation of the correlation coefficient Cc or the correlation coefficient exceeding a predetermined threshold value _CTH may be selected. You may select the displacement obtained by the correlation calculation with the highest correlation coefficient.

(Second embodiment)
Next, a second embodiment will be described. The second embodiment has the same basic configuration as that of the first embodiment, and the description of matters similar to those of the first embodiment is omitted.

  Also in this example, the elastic image data creation unit 52 performs the correlation calculation of the correlation window and the one sound in creating elastic image data for the correlation window on one sound ray, as in the first embodiment. The elastic image data is created according to the correlation calculation of the other sound ray correlation window on another sound ray different from the line, but the specific method is different.

  Specifically, in this example, as shown in FIG. 9, the elastic image processing unit 5 includes an average calculation unit 54 in addition to the physical quantity calculation unit 51 and the elastic image data creation unit 52. . The average calculation unit 54 is an example of an embodiment of the average calculation unit 54 in the present invention, and the displacement obtained by the correlation calculation of the correlation window and the displacement obtained by the correlation calculation of the other sound ray correlation window. And the average calculation. The elastic image data creating unit 52 creates elastic image data for the correlation window based on the average value obtained by the average calculating unit 54.

For example, when creating elastic image data for the correlation windows W11c and W21c, the physical quantity calculator 51 first calculates the correlation calculation of the correlation windows W11a and W21a, the correlation calculation of the correlation windows W11b and W21b, and the correlation. Correlation calculation of the windows W11c and W21c, correlation calculation of the correlation windows W11d and W21d, and correlation calculation of the correlation windows W11e and W21e are performed to calculate displacements Xa, Xb, Xc, Xd, and Xe, respectively. Then, the average calculation unit 54 performs averaging operation of the displacement Xa～Xe, calculates the average value _{X AV} of each displacement.

  Incidentally, the displacements Xa, Xb, Xd, and Xe for the other sound ray correlation window may be calculated by the physical quantity calculation unit 51 in performing the average calculation, but already the elastic image data for the other sound ray correlation window. If the displacements Xa, Xb, Xd, and Xe are calculated at the time of creating the value, the values calculated at this time may be used for the average calculation without calculating again.

  Here, when the average calculation is performed, the displacements Xa, Xb, Xc, Xd, and Xe may be weighted according to a correlation coefficient. That is, the displacement Xa is multiplied by the weighting coefficient corresponding to the correlation coefficient Ca in the correlation calculation between the correlation windows W11a and W21a, and the correlation coefficient Cb according to the correlation calculation between the correlation windows W11b and W21b is determined. In the correlation calculation between the correlation windows W11d and W21d, the displacement Xb is multiplied, the weighting coefficient corresponding to the correlation coefficient Cc in the correlation calculation between the correlation windows W11c and W21c is multiplied by the displacement Xc. The weighting coefficient corresponding to the correlation coefficient Cd is multiplied by the displacement Xd, and the weighting coefficient corresponding to the correlation coefficient Ce in the correlation calculation between the correlation windows W11e and W21e is multiplied by the displacement Xe to perform an average calculation. Do. The weight coefficient is a coefficient that increases as the correlation coefficient increases.

Wherein when the average value _{X AV} by average calculation unit 54 is calculated, the elastic image data generating unit 52, based on the average value _{X AV,} the correlation window W11c, creates an elastic image data for W21c.

Incidentally, in this example, the setting of the correlation window in the frame (i) is performed in the same manner as in the first embodiment. On the other hand, the setting of the correlation window in the frame (ii) will be described. For example, the correlation window W22c (post correlation window) set next to the correlation window W21c on the sound ray L2c is the average value X _AV. , The amount of movement from the correlation window W21c is determined and set.

According to the present embodiment described above, for example, the correlation window W11c, elastic image data for W21c is created based on the average value X _AV obtained by the average calculation unit 54. Accordingly, even when the displacement Xc obtained as a result of the correlation calculation of the correlation windows W11c and W21c does not accurately reflect the elasticity of the living tissue, the displacement Xa, Xb obtained by the correlation calculation of the other sound ray correlation window. , Xd, and Xe more accurately reflect the elasticity of the living tissue, the elasticity image data for the correlation windows W11c and W21c should be data that more accurately reflects the elasticity of the living tissue than before. Can do. Thereby, it is possible to obtain an elasticity image that accurately reflects the elasticity of the living tissue with respect to the correlation windows W11c and W21c.

  Further, a post-correlation window (such as the correlation window W22c) in which the correlation calculation is performed after the correlation window W21c in the frame (ii) is set based on the average value obtained by the average calculation of the average calculation unit 54. The Thereby, even when the displacement Xc obtained by the correlation calculation of the correlation windows W11c and W21c does not accurately reflect the elasticity of the living tissue, the degree of matching with the correlation window of the frame (i) is higher than the conventional level. So that the post correlation window can be set in the frame (ii). As described above, it is possible to suppress the appearance of linear artifacts in the elastic image, and it is possible to obtain an elastic image that more accurately reflects the elasticity of the living tissue than in the past.

  Next, a modification of the second embodiment will be described. In this modification, as shown in FIG. 10, the elastic image processing unit 5 further includes an error determination unit 55. The error determination unit 55 determines whether or not these displacements are errors when performing the average calculation by the average calculation unit 54 with respect to the displacements used for the average calculation. Then, the average calculation unit 54 performs an average calculation except for the displacement that is regarded as an error. The error determination unit 55 is an example of an embodiment of an error determination unit in the present invention.

  For example, the error determination unit 55 determines whether there is an error for these displacements Xa to Xe when performing the average calculation of the displacements Xa, Xb, Xc, Xd, and Xe. Then, the average calculation unit 54 performs an average calculation except for the displacements determined by the error determination unit 55 among the displacements Xa to Xe. That is, the average calculation unit 54 determines that an error has been determined if any of Xa, Xb, Xd, and Xe, which are displacements obtained by the correlation calculation of the other sound ray correlation window, is determined to be an error. An average operation of the displacement in the other sound ray correlation window except the displacement Xc obtained by the correlation operation of the correlation windows W11c and W21c is performed. In addition, when the displacement Xc is determined to be an error, the average calculation unit 53 performs an average calculation of the displacements Xa, Xb, Xd, and Xe.

As an example of the determination method by the error determination unit 55, there is a method of determining whether there is an error based on the correlation coefficient C in the correlation calculation in which the displacement of the determination target is obtained. In this case, a predetermined threshold value _CTH is set in advance for the correlation coefficient C, and when the correlation coefficient C is smaller than the threshold value _CTH , the error determination unit 55 determines that an error has occurred. For example, the error determination unit 55, when determining whether or not an error for the displacement Xa, the correlation windows W11a, the correlation coefficient Ca correlation calculation performed between W21a compared with the threshold C _TH, the When the correlation coefficient Ca is lower than the threshold value _CTH , the displacement Xa is determined as an error.

  Another example of the determination method by the error determination unit 55 is a method of determining an error when the displacement to be determined is not within a predetermined range set in advance. Here, the predetermined range is a range of displacement that is set by an operator, for example, and the operator thinks that the operator normally obtains.

  Furthermore, as another example of the determination method by the error determination unit 55, there is a method for determining whether or not the displacement of the determination target is an error based on the distribution of the displacement of the other determination target. Specifically, the error determination unit 55 determines an error when the displacement of the determination target is significantly different from the distribution of the displacements of other determination targets. The range determined to be significantly different is set in advance by the operator's judgment.

  For example, when determining whether or not the displacement Xa is an error, the error determination unit 55 obtains an average value of the displacements Xb, Xc, Xd, and Xe, and ± n set by the operator for the average value If the displacement Xa is not within the range of%, it is determined that an error has occurred. As described above, the error determination unit 55 determines whether there is an error based on the distribution of the displacements Xb, Xc, Xd, and Xe.

  As mentioned above, although this invention was demonstrated by each said embodiment, of course, this invention can be variously implemented in the range which does not change the main point. For example, the physical quantity calculation unit 51 may calculate the strain or elastic modulus of the living tissue instead of the displacement due to the deformation of the living tissue as the physical quantity related to the elasticity of the living tissue.

DESCRIPTION OF SYMBOLS 1 Ultrasonic diagnostic apparatus 51 Physical quantity calculation part 52 Elastic image data preparation part 53 Selection part 54 Average calculation part 55 Error determination part W11c, W21c Correlation window W11a, W21a, W11b, W21b, W11d, W21d, W11e, W21e Correlation window (others) Sound ray correlation window)
W12c, W22c correlation window (post correlation window)

Claims (14)

A correlation window is set for two echo signals obtained by transmitting / receiving ultrasound to / from a living tissue and on the same sound ray belonging to two temporally different frames. A physical quantity calculation unit for performing a correlation calculation to calculate a physical quantity related to the elasticity of the living tissue;
Based on the physical quantity, an elasticity image data creation unit that creates elasticity image data of biological tissue for each correlation window;
In creating elastic image data for a correlation window on one sound ray, the correlation between the calculated value obtained by the correlation calculation of the correlation window and the other sound ray correlation window on another sound ray different from the one sound ray. A selection unit that selects a calculated value suitable for creating elastic image data for the correlation window from the calculated value obtained by the calculation;
With
The ultrasonic diagnostic apparatus, wherein the elasticity image data creation unit creates elasticity image data for the correlation window based on the calculated value selected by the selection unit.   The physical quantity calculation unit, based on the calculated value selected by the selection unit, sets a post-correlation window set next to the correlation window in an echo signal on one sound ray belonging to one of the two frames. The ultrasonic diagnostic apparatus according to claim 1, wherein the ultrasonic diagnostic apparatus is set.   The selection unit selects a calculation value suitable for creation of elasticity image data for the correlation window, and determines whether a correlation coefficient of a correlation calculation from which the calculation value is obtained or whether the calculation value is within a predetermined range. The ultrasonic diagnostic apparatus according to claim 1, wherein the ultrasonic diagnostic apparatus is performed based on the above.   When the correlation coefficient in the correlation calculation of the correlation window exceeds a predetermined threshold, the selection unit calculates a calculation value obtained by the correlation calculation of the correlation window suitable for creating elastic image data for the correlation window. When the correlation coefficient in the correlation calculation of the correlation window is less than or equal to the predetermined threshold, the calculated value obtained by the correlation calculation of the other sound ray correlation window, Selecting a calculated value obtained by correlation calculation of a correlation coefficient exceeding the correlation coefficient in the correlation calculation or a calculated value within a predetermined range as a calculated value suitable for creation of elastic image data for the correlation window; The ultrasonic diagnostic apparatus according to claim 1, wherein the ultrasonic diagnostic apparatus is characterized.   The selection unit uses the correlation coefficient in the correlation calculation of the correlation window and the correlation coefficient in the correlation calculation of the other sound ray correlation window to calculate a value obtained by the correlation calculation having the highest correlation coefficient. The ultrasonic diagnostic apparatus according to claim 1, wherein the ultrasonic diagnostic apparatus is selected as a calculated value suitable for creating elastic image data for a window.   When the calculated value obtained by the correlation calculation of the correlation window is within a predetermined range, the selection unit generates the elastic image data for the correlation window using the calculated value obtained by the correlation calculation of the correlation window. When the calculated value obtained by the correlation calculation of the correlation window is out of a predetermined range while being selected as a suitable calculated value, the calculated value obtained by the correlation calculation of the other sound ray correlation window, The calculated value obtained by the correlation calculation of the correlation coefficient exceeding the correlation coefficient in the correlation calculation of the correlation window or the calculated value within the predetermined range is a calculated value suitable for creating elastic image data for the correlation window. The ultrasonic diagnostic apparatus according to claim 1, wherein the ultrasonic diagnostic apparatus is selected.   Based on the distribution of the calculated values obtained by the correlation calculation of the other sound ray correlation window for the plurality of other sound rays, the selection unit obtains the calculated value obtained by the correlation calculation of the correlation window as the correlation value. When it is determined whether it is suitable for the creation of elastic image data for the window, and when it is determined that it is suitable for the creation of elastic image data for the correlation window, the calculated value obtained by the correlation calculation of the correlation window is If it is selected as a calculated value suitable for the creation of elastic image data for the correlation window, on the other hand, if it is determined that it is not suitable for the creation of elastic image data for the correlation window, any one of the other sound rays The calculated value obtained by the correlation calculation of the correlation window and obtained by the correlation calculation of the correlation coefficient exceeding the correlation coefficient in the correlation calculation of the correlation window. The calculated value or the calculated value within the predetermined range is selected as a calculated value suitable for creating elasticity image data for the correlation window. Ultrasound diagnostic equipment. A correlation window is set for two echo signals obtained by transmitting / receiving ultrasound to / from a living tissue and on the same sound ray belonging to two temporally different frames. A physical quantity calculation unit for performing a correlation calculation to calculate a physical quantity related to the elasticity of the living tissue;
Based on the physical quantity, an elasticity image data creation unit that creates elasticity image data of biological tissue for each correlation window;
An error determination unit that determines whether or not there is an error for a calculated value obtained by correlation calculation of a correlation window on one sound ray;
In creating elastic image data for a correlation window on the one sound ray , when the error determination unit determines that the calculated value obtained by the correlation calculation of the correlation window is an error, the one sound ray is An average calculation unit that performs an average calculation of the calculated values obtained by the correlation calculation of the other sound ray correlation window on a plurality of different other sound rays;
Further comprising
The ultrasonic diagnostic apparatus, wherein the elastic image data creation unit creates elastic image data for the correlation window based on the average value obtained by the average calculation unit.   The ultrasonic diagnostic apparatus according to claim 8, wherein the error determination unit determines whether there is an error based on a correlation coefficient in a correlation calculation in which a calculated value to be determined is obtained.   The ultrasonic diagnostic apparatus according to claim 8, wherein the error determination unit determines an error when a calculated value to be determined is not within a predetermined range set in advance.   The ultrasonic diagnostic apparatus according to claim 8, wherein the error determination unit determines whether or not the calculated value of the determination target is an error based on a distribution of calculated values of other determination targets.   In the echo signal on one sound ray belonging to one of the two frames, the physical quantity calculation unit sets a post-correlation window set next to the correlation window to an average value obtained by the average calculation unit. It sets based on, The ultrasonic diagnostic apparatus as described in any one of Claims 8-11 characterized by the above-mentioned.   The ultrasonic diagnostic apparatus according to any one of claims 8 to 12, wherein the average calculation unit performs weighting according to a correlation coefficient for a calculated value that is a target of the average calculation.   The ultrasonic diagnostic apparatus according to claim 1, wherein the other sound ray correlation window is located at the same depth in the biological tissue as the correlation window.

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