JP2008154626A - Ultrasonic diagnostic system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize an ultrasonic diagnostic system which enables the stable generation of an image of an interface between different tissues of a subject. <P>SOLUTION: The ultrasonic diagnostic system 20 is constituted of a means which generates ultrasonic images of the tissues at sectional sites of the subject 18 from ultrasonic tomographic data obtained by measurements made by the repeated transmission and reception of ultrasonic waves to and from the subject and a display means for displaying the ultrasonic images. A correlation value or variations in the correlation value is determined for the ultrasonic tomographic data at a plurality of measuring points of the sectional sites of the subject from a pair of ultrasonic tomographic data acquired at different acquisition timings. The results are compared with the respective thresholds to be divided and an image 30 of the interface between the tissues is generated to be displayed on a display means together with the ultrasonic wave images. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an ultrasonic diagnostic apparatus, and more particularly to an ultrasonic diagnostic apparatus capable of displaying a boundary between different tissues on a tomographic image of a subject as an image.

  A conventional general ultrasonic diagnostic apparatus includes an ultrasonic transmission / reception control unit that controls transmission / reception of ultrasonic waves, an ultrasonic transmission / reception unit that transmits and receives ultrasonic waves to a subject, and a reflected echo from the ultrasonic reception unit. A tomographic scanning means for repeatedly obtaining ultrasonic layer data in a subject including a moving tissue using a signal at a predetermined period; and an image display means for displaying time-series ultrasonic tomographic data obtained by the tomographic scanning means. Had been configured. The structure of the tissue inside the subject is displayed as, for example, a B-mode image.

  On the other hand, in recent years, on the ultrasonic transmission / reception surface of the ultrasonic probe, an external force is applied by a manual method from the body surface of the subject, the tissue is compressed, and a pair of different acquisition times (for example, It is known to obtain the displacement at each point using the correlation calculation of the ultrasonic tomographic data of two temporally adjacent frames). Further, a technique is known in which distortion is measured by spatially differentiating the displacement and the distortion data is imaged.

  Furthermore, a technique for imaging elasticity information typified by tissue Young's modulus and the like from stress distribution and strain data due to external force has become realistic.

  By the way, in Patent Document 1, the elasticity information for each measurement point in the region of interest (ROI) is binarized based on a set threshold value, and the boundary line between the two regions, a region larger than the threshold value and a smaller region, is imaged. Thus, it is described that the contours of tissues having different elasticity are imaged.

JP 2004-135929 A

  However, in the technique of Patent Document 1, for example, elasticity information such as a tissue that moves from the ROI to the outside during the acquisition time interval of a pair of ultrasonic tomographic data or a tissue that cannot maintain a form against compression. In the case where a tissue that cannot be accurately obtained is included, there is a possibility that the boundary between the tissues cannot be clearly imaged.

  Therefore, it is desired to generate a boundary image between different tissues stably using other means instead of generating a boundary image between tissues based on elasticity information as in the technique of Patent Document 1.

  An object of the present invention is to realize an ultrasonic diagnostic apparatus that stably generates an image of a boundary between different tissues of a subject.

  In order to solve the above problems, the ultrasonic diagnostic apparatus of the present invention is based on ultrasonic tomographic data measured by repeatedly transmitting and receiving ultrasonic waves to and from a subject, and ultrasonic waves of a tissue at a tomographic site of the subject. The image forming apparatus includes a unit that generates an image and a display unit that displays the ultrasonic image. Then, a correlation value of ultrasonic tomographic data at a plurality of measurement points of a tomographic region of the subject is obtained based on a pair of ultrasonic tomographic data having different acquisition times, and a boundary image between tissues is generated based on the correlation value. And displaying on the display means together with the ultrasonic image.

  According to this, for example, even in a situation where the elasticity information cannot be obtained accurately, the correlation value of the ultrasonic tomographic data for each of a plurality of measurement points from a pair of ultrasonic tomographic data having different acquisition times. Is required. Since this correlation value is a value representing the degree of tissue displacement for each measurement point, a boundary image between different tissues can be stably generated based on the correlation value.

  In this case, the correlation value of the ultrasonic tomographic data at a plurality of measurement points may be an autocorrelation value obtained based on a correlation process in a one-dimensional direction or a two-dimensional direction of a pair of ultrasonic tomographic data having different acquisition times. it can.

  If correlation processing is performed in the two-dimensional direction, the accuracy of the correlation value can be improved. Since the correlation processing in the two-dimensional direction has a large processing load, it is possible to appropriately combine the correlation processing in the one-dimensional direction and the two-dimensional direction in consideration of the balance between the accuracy of the correlation value and the processing speed. is there.

  The boundary image described above classifies at least one of the correlation value at each measurement point and the variation of the correlation value at each measurement point by comparing with the set threshold value for each measurement point, and the classification is different from the adjacent measurement points. It is preferable that the portion is imaged.

  In other words, for example, a lesion site such as a thrombus or plaque in a blood vessel is surrounded by a blood stream with intense movement, so the correlation value of each measurement point within the lesion site is relatively stable. On the other hand, the correlation value of each measurement point in the region of the blood flow region is a random and unstable value. In such a case, the correlation value is not simply compared with the set threshold value, but the correlation value variation is obtained from the correlation value, and the correlation value variation is compared with the set threshold value to obtain an area larger than the threshold value. It is preferable to divide into regions smaller than the threshold value and image a portion corresponding to the boundary of the division as a boundary image.

  In this case, the variation of the correlation value can be any one of the standard deviation and the variance between the correlation value at each measurement point and the correlation values at the measurement points around this measurement point. That is, for example, the correlation value variation of a certain target measurement point is obtained by calculating the correlation value of n + 1 points, which is a combination of the correlation value of this target measurement point and the correlation values of n measurement points around this target measurement point, as a population. Standard deviation or variance. Note that the range of the standard deviation or variance population can be arbitrarily set.

  Further, the correlation value itself may be classified by comparing with the set threshold value, and a boundary image may be obtained by imaging a portion where the classification is different from the adjacent measurement point, or based on the boundary image and the above-described variation of the correlation value. It is also possible to display in combination with the boundary image.

  As described above, the above-described ultrasonic diagnostic apparatus is applied to the blood vessel portion of the subject, and generates a boundary image of the boundary portion between the blood flow portion in the blood vessel and the lesion portion formed in the blood vessel. It is particularly suitable for the case.

  Further, the above-described ultrasonic image can be an ultrasonic tomographic image or / and an elastic image which is a so-called B-mode image of a tomographic region of the subject. This elasticity image is based on a pair of ultrasonic tomographic data with different acquisition times measured in the process of changing the pressure applied to the tissue of the subject, and the ultrasonic tomographic data at a plurality of measurement points at the tomographic site of the subject. A displacement can be obtained and an image generated based on the displacement can be obtained.

  By displaying the boundary image superimposed on the so-called B-mode image and grasping the overall structure of the tissue in the tomographic region of the subject with the B-mode image, for example, a tissue of interest such as a lesion site and surrounding tissue It is easy to specify the lesion site using the border image of the lesion site, in other words, the contour image of the lesion site. Further, by displaying the elasticity information correlated with the hardness or softness of the tissue on such an image, it may be possible to provide a useful diagnostic image for the examiner to select a treatment method.

  As described above, when the ultrasonic tomographic data is measured in the process of changing the pressure applied to the tissue of the subject, at least one of the displacement at each measurement point and the variation in displacement at each measurement point is determined for each measurement point. It is also possible to classify the image by comparing with the set threshold value, image a portion having a different classification from the adjacent measurement point, and display it on the display unit together with the boundary image.

  Here, the variation in displacement can be either one of the standard deviation and the variance between the displacement at each measurement point and the displacement at the measurement points around this measurement point, similarly to the above-described variation in the correlation value.

  As described above, when the displacement of each measurement point is required, a boundary image based on at least one of the displacement and the variation of the displacement is generated and displayed in combination with the boundary image based on the above-described correlation value as appropriate. Thus, the accuracy of the boundary image provided to the examiner can be further improved.

  In addition, when displaying an elasticity image of the tissue of the subject, an elasticity image is not displayed for all measurement points, but only one of the measurement points divided by comparison with the set threshold value described above. It can also be displayed.

  According to the present invention, it is possible to realize an ultrasonic diagnostic apparatus that stably generates an image of a boundary between different tissues of a subject.

  Hereinafter, embodiments of an ultrasonic diagnostic apparatus to which the present invention is applied will be described. In the following description, the same functional parts are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is a block diagram showing an embodiment of the ultrasonic diagnostic apparatus of the present invention. The ultrasonic diagnostic apparatus 20 has a function of obtaining a tomographic image of a diagnostic region of a subject using ultrasonic waves and displaying an elastic image representing the hardness or softness of the tissue.

  As shown in FIG. 1, the ultrasonic diagnostic apparatus 20 includes an ultrasonic transmission / reception control circuit 1, a transmission circuit 2, an ultrasonic probe 3, a reception circuit 4, a phasing addition circuit 5, and signal processing. Unit 6, monochrome scan converter 7, RF signal frame data selection unit 8, displacement measurement unit 9, boundary region detection unit 10, strain amount and elastic modulus calculation circuit 11, color scan converter 12, and switching addition And a display unit 14, an image display 14, a control unit 15, and a keyboard 16.

  The ultrasonic diagnostic apparatus 20 is appropriately operated by an external operator via the keyboard 16 and the control unit 15.

  As shown in FIG. 1, the ultrasonic probe 3 used in contact with the subject 18 is not shown in the figure, but includes a number of transducers that are the sources of ultrasonic waves and receive reflected echoes. It is formed in a strip shape, and performs mechanical or electronic beam scanning to transmit ultrasonic waves to the subject and receive reflected echoes. Each vibrator generally has a function of converting a pulse wave or a continuous wave transmission signal supplied from the transmission circuit 2 into an ultrasonic wave and emitting the ultrasonic wave and an ultrasonic signal emitted from the inside of the subject. It is formed to have a function of converting to a received signal and outputting it.

  Here, in the present embodiment, a case where the ultrasonic diagnostic apparatus is operated while pressing the subject using the probe 3 will be described as an example. As shown in FIG. 2, the compression operation of the subject is performed for the purpose of effectively giving a stress distribution in the body cavity of the diagnosis site of the subject 18 while performing ultrasonic transmission / reception with the probe 3. The ultrasonic transmission / reception surface 21 and a compression plate 22 are mounted so as to match the transmission / reception surface, and the compression surface constituted by the ultrasonic transmission / reception surface 21 and the compression plate 22 of the probe 3 is the body surface of the subject. The subject is pressed by manually moving the compression surface up and down.

  As a compression method, for example, as shown in FIGS. 3 (A) to 3 (C), a certain stress is applied by applying the probe 3 to the subject 18 so that a distortion of about 5% to 20% is generated. In the initial compression state, pressurization and depressurization can be repeated so as to cause a slight strain change of about 0.2% to 1%.

  The ultrasonic transmission / reception control circuit 1 controls the transmission timing of ultrasonic pulses for driving a plurality of transducers of the probe 3 so as to form an ultrasonic beam toward the focal point set in the subject 18. It has become. The ultrasonic transmission / reception control circuit 1 is configured to electronically scan an ultrasonic beam in the arrangement direction of the transducers of the probe 3. The transmission circuit 2 generates a transmission pulse for driving the probe 3 to generate an ultrasonic wave, and has a convergence point of the ultrasonic wave transmitted by the built-in transmission phasing and adding circuit. The depth is set.

  On the other hand, the probe 3 receives a reflected echo signal generated from the inside of the subject 18 and outputs it to the receiving circuit 4. The receiving circuit 4 captures the reflected echo signal in accordance with the timing signal input from the ultrasonic transmission / reception control circuit 1 and performs reception processing such as amplification with a predetermined gain. The number of reflected echo signals corresponding to the number of amplified transducers is input to the phasing / adding circuit 5 as independent reflected echo signals, the phase is controlled by the phasing / adding circuit 5, and one or more convergence points are obtained. An ultrasonic beam is formed for the point.

  A reflection echo signal (hereinafter referred to as ultrasonic tomographic data) subjected to phasing addition in the phasing addition circuit 5 is input to the signal processing unit 6 and signals such as gain correction, log compression, detection, contour enhancement, filter processing, and the like. Processing is done. The radio frequency (RF) signal of the ultrasonic tomographic data generated in the phasing addition circuit 5 may be a complex demodulated I and Q signal. In this manner, the probe 3 scans an ultrasonic beam in a certain direction in the body of the subject 18 to obtain ultrasonic tomographic data corresponding to one tomographic image.

  The ultrasonic tomographic data processed by the signal processing unit 6 is guided to a black and white scan converter 7 where it is converted into a digital signal and also converted into two-dimensional tomographic image data corresponding to the scanning plane of the ultrasonic beam. . That is, the black and white scan converter 7 acquires RF signal frame data in the subject 18 including a moving tissue in an ultrasonic cycle, converts the frame data into an image, and displays the tomographic data for reading in synchronization with the television. It becomes a means for controlling the scanning means and the system. Specifically, an A / D converter that converts a reflected echo signal from the signal processing unit 6 into a digital signal, and a plurality of sheets that store tomographic image data digitized by the A / D converter in time series. It consists of a frame memory and a controller that controls these operations.

  The signal processing unit 6 and the monochrome scan converter 7 constitute a tomographic image reconstruction unit. The tomographic image data output from the monochrome scan converter 7 is supplied to the image display 14 via the switching adder 13 so that the tomographic image is displayed.

  The image display 14 displays time-series tomographic image data obtained by the black and white scan converter 7, that is, a B-mode tomographic image, and converts the image data input via the switching adder 13 into an analog signal D. / A converter and a color television monitor that receives an analog video signal from the D / A converter and displays it as an image.

  In this embodiment, the RF signal frame data selection unit 8, the displacement measurement unit 9, the boundary part detection unit 10, and the strain amount and elastic modulus calculation circuit 11 are branched from the output side of the phasing addition circuit 5. Etc. are provided. Further, a color scan converter 12 is provided at the subsequent stage of the boundary portion detection unit 10 and the strain amount / elastic modulus calculation circuit 11, and a switching adder 13 is provided at the output side of the monochrome scan converter 7 and the color scan converter 12. ing.

  The RF signal frame data selection unit 8 stores the RF signal frame data output from the phasing addition circuit 5 one after another at a frame rate of the ultrasonic diagnostic apparatus in the frame memory provided in the RF signal frame data selection unit 8. (The RF signal frame data currently secured is referred to as RF signal frame data N), and the past RF signal frame data N-1, N-2, N- 3... One RF signal frame data is selected from NM (referred to as RF signal frame data X), and a pair of RF signal frame data N and RF signal frame data X are sent to the displacement measuring unit 9. It plays a role of output.

  Next, as will be described in detail later, the displacement measuring unit 9 which is a characteristic part of the present invention is displaced based on a pair of RF signal frame data selected by the RF signal frame data selecting unit 8 as shown in FIG. Frame data and correlation frame data are generated. The correlation frame data generated in this way is output to the boundary part detection unit 10, and the displacement frame data is output to the strain amount and elastic modulus calculation circuit 11.

  Moreover, the boundary part detection part 10 which is the characteristic part of this invention expresses the boundary between the different tissues in the tomographic part of the subject based on the correlation frame data output from the displacement measurement part 9, although details will be described later. An image is generated.

  The strain amount and elastic modulus calculation circuit 11 calculates the strain amount and the elastic modulus at each measurement point on the tomographic image from the displacement frame data output from the displacement measuring unit 9 to obtain numerical data of the strain amount or elastic modulus (elastic frame). Data) and output to the color scan converter 12.

  The calculation of the strain performed in the strain amount and elastic modulus calculation circuit 11 is calculated by, for example, spatially differentiating the displacement. For example, the Young's modulus Ym, which is one of the elastic moduli, is obtained by dividing the stress (pressure) at each calculation point by the strain amount at each calculation point, as shown in the following equation. .

In the following formulas, the indices i and j represent the coordinates of the frame data.
Ymi, j = pressure (stress) i, j / (strain amount i, j) (i, j = 1, 2, 3,...)
Here, the pressure applied to the body surface is measured directly by the pressure sensor interposed between the contact surface of the body surface and the compression mechanism, or the patent application previously filed by the applicant of the present application. It can be measured by a method as described in JP 2005-66041 A.

  The strain amount and elastic modulus calculation circuit 11 performs various image processing such as smoothing processing, contrast optimization processing within the coordinate transformation plane, and smoothing processing in the time axis direction between frames on the calculated elastic frame data. The processed elastic frame data may be output as the strain amount.

  As shown in FIG. 5, the color scan converter 12 includes a gradation circuit 121 and a hue conversion circuit 122. From the command or distortion amount and elastic modulus calculation circuit 11 from the control unit 15 of the ultrasonic diagnostic apparatus. The upper limit value and the lower limit value as the gradation selection range in the output elastic frame data are input, and the boundary trace frame data output from the boundary portion detection unit 10 is used to convert the elastic image data from the elastic frame data. Including a hue conversion process for providing hue information such as red, green, and blue. The color scan converter 12 may be the black and white scan converter 7. For example, an area where a large distortion is measured increases the luminance of the area in the elastic image data, and conversely, an area where the distortion is measured is an elastic image. You may make it make the brightness | luminance of the said area | region in data dark.

  In the gradation circuit 121 in the color scan converter 12, the elasticity in the traced region is determined from the elastic frame data output from the strain amount and elastic modulus calculation circuit 11 and the boundary trace frame data output from the boundary part detection 10. Only the frame data is converted into 255 levels according to the value of the element data of the elastic frame data within the area to be commanded or gradationed from the control unit 15 of the ultrasonic diagnostic apparatus, and the other areas are rejected. Thus, elastic gradation frame data is generated. At this time, the gradation region is within the region of interest (ROI) set by the control unit 15 of the ultrasonic diagnostic apparatus, but can be arbitrarily changed by the operator.

  For example, in the elastic gradation frame data, the hue conversion circuit 122 in the color scan converter 12 converts the corresponding area in the elastic image frame data into a red code and reversely distorts the area where the distortion is measured. For the area measured with a small size, the corresponding area in the elastic image frame data is converted into a blue code, and when it is outside the trace area, it is converted into black.

  The switching adder 13 inputs black and white tomographic image data from the black and white scan converter 7 and elastic image frame data output from the color scan converter 12 and serves as means for adding or switching both images. Only the acoustic tomographic image data or the color elastic image data is output, or both image data are added and synthesized, or the two images are displayed side by side. Further, for example, as described in Japanese Patent Application Laid-Open No. 2004-135929 filed earlier by the applicant of the present application, a color tomographic image may be displayed on a black and white tomographic image in a translucent manner. good. At this time, the black and white tomographic image is not limited to a general B-mode image, and a tissue harmonic tomographic image obtained by imaging the harmonic component of the received signal may be used.

  Further, image data output from the switching adder 13 is stored in a memory (not shown), and past image data is recalled and displayed on the image display 14 in accordance with a command from the control unit 15 or the like. Also good. Further, the selected image data may be transferred to a recording medium such as an MO.

  Next, a basic operation of the ultrasonic diagnostic apparatus according to this embodiment configured as described above will be described. First, while changing the pressure applied to the subject 18 by the probe 3, the subject 18 is scanned with an ultrasonic beam and the reflected echo signal from the scanning surface is continuously received. Then, based on the RF signal output from the phasing addition circuit 5, the ultrasonic tomographic image is reconstructed by the signal processing unit 6 and the black and white scan converter 7 and displayed on the image display 14 via the switching adder 13. The

  On the other hand, the RF signal frame data selection unit 8 captures the RF signal and repeatedly acquires the frame data in synchronization with the frame rate in the process in which the pressure applied to the subject 18 changes, and the time is stored in the built-in frame memory. Save in sequence order. Then, a plurality of pairs of frame data are successively selected and output to the displacement calculation unit 9 with frame data consisting of a pair of reflected echo signals having different acquisition times as units.

  The displacement calculation unit 9 generates displacement frame data and correlation frame data based on the selected pair of frame data, the correlation frame data is sent to the boundary part detection unit 10, and the displacement frame data is a strain amount and elastic modulus calculation circuit. 11 is output.

  The correlation frame data input to the boundary part detection unit 10 is subjected to various processes and output to the color scan converter 12 as boundary trace frame data.

  On the other hand, the displacement frame data is input to the strain amount and elastic modulus calculation circuit 11 to calculate preset elastic information such as strain and elastic modulus at each measurement point, and the necessary elastic frame data is converted into a color scan converter. 12 is output.

  The boundary trace frame data and the elastic frame data are input to the color scan converter 12 to generate a boundary image and an elastic image of the tissue of the subject, and are displayed on the image display 14 via the switching adder 13.

  Below, the displacement measurement part 9 and the boundary part detection part 10 which are the characteristic parts of the ultrasound diagnosing device of this embodiment are demonstrated in detail.

  First, as shown in FIG. 4, the displacement measuring unit 9 generates not only the displacement frame data necessary for generating the boundary image described in Patent Document 1 described in the background art described above, but also correlation frame data. Has also generated.

  Specifically, based on the pair of RF signal frame data selected by the RF signal frame data selection unit 8, for example, for each measurement point in the set region of interest (ROI), one-dimensional or two-dimensional of the RF signal. Correlation processing is executed to measure the displacement or movement vector (direction and magnitude of displacement) of each measurement point on the tomographic image, and generate displacement frame data and correlation frame data.

  As a method for detecting this movement vector, for example, there are a block matching method and a gradient method as described in JP-A-5-317313. The block matching method divides the image into blocks of, for example, N × N pixels, searches the previous frame for the block closest to the target block in the current frame, and performs predictive coding with reference to these blocks Is to do.

  The correlation value can be calculated by, for example, an autocorrelation function of a pair of RF signals. The autocorrelation function is a function indicating how much similarity there is between a pair of RF signals. For example, if both signal waveforms are completely matched, the correlation value is 1, and as both signal waveforms deviate. It becomes 0 when it becomes small and becomes completely inconsistent. Accordingly, the correlation value is a value representing the degree of tissue displacement at each measurement point.

  Here, if the correlation processing is performed in the two-dimensional direction, the accuracy of the correlation value can be improved. However, since the correlation processing in the two-dimensional direction has a large processing load, the balance between the accuracy of the correlation value and the processing speed can be improved. In consideration, it is possible to use a combination of correlation processing in the one-dimensional direction and the two-dimensional direction as appropriate, and the range of the correlation window can be set as appropriate.

  When the correlation frame data, which is the correlation value at each measurement point, is calculated in this way, next, the boundary part detection unit 10 calculates standard deviation frame data representing the variation of the correlation value from the correlation frame data.

  For example, the standard deviation or variance is calculated using the correlation value at a certain measurement point of interest and the correlation values at the measurement points in the surrounding setting area as a population, and this is used as the variation value at the measurement point of interest. It is. In addition, the standard deviation or variance calculated in this way may be used as a variation value of a set of measurement points in the setting area. Then, the standard deviation frame data is generated by performing the same calculation for each measurement point or each set of measurement points.

  As shown in FIG. 6A, the standard deviation or variance becomes a large value when the correlation value of the population varies, and as shown in FIG. 6B, the standard deviation or variance becomes a small value when the correlation value of the population does not vary. It will be. Therefore, the standard deviation frame data indicates whether the tissue of the subject at a certain measurement point is displaced in the same way in the surrounding tissue or group, or dissimilarly, or because the displacement is too large. Becomes an index value indicating whether or not a random value is returned as the correlation value.

  6A and 6B, the horizontal axis is the correlation value, and the vertical axis is the number of appearances. In the present embodiment, the standard deviation or variance has been described as an example. However, the present invention is not limited to this, and any calculation process that expresses variations in correlation values can be applied as appropriate.

  When the standard deviation frame data is calculated, each measurement point or a set of a plurality of measurement points is converted into a standard deviation or variance based on a signal SDth that is a set threshold value input from the control unit 15 of the ultrasonic diagnostic apparatus. Classification is made depending on whether it is larger or smaller than SDth. For example, as shown in FIG. 7, binarization can be performed with 1 being greater than SDth and 0 being smaller. FIG. 7 is a schematic diagram showing a state in which each measurement point is binarized by 1 or 0. The setting threshold value SDth can be arbitrarily set and changed by various input devices such as a keyboard, a mouse, and a touch panel.

  Then, each measurement point is traced in order in the vertical direction and the horizontal direction, and as shown by hatching in FIG. 7, a place having a value different from that of the adjacent measurement point is regarded as a boundary between different tissues. Trace frame data is generated. In this description, the example in which the boundary image is generated at one measurement point when the value is traced sequentially in the vertical direction and the horizontal direction and the value becomes 0 to 1 or 1 to 0 is shown. The boundary trace frame data can be generated by using various algorithms such as generating boundary images at both measurement points of the boundary where the value changes.

  Further, instead of providing a threshold value, a contour extraction method, for example, primary differentiation, secondary differentiation, or the like is also possible. Further, the operator may trace the correlation image. The boundary trace frame data generated in this way is output to the color scan converter 12.

  FIG. 8 is a diagram schematically illustrating an image obtained by imaging a blood vessel of a subject, a tissue around the blood vessel, and a lesion site such as a thrombus or plaque formed in the blood vessel using the ultrasonic diagnostic apparatus of the present invention. It is.

  FIG. 8A is a schematic diagram of a tomographic part in a state where no boundary image is generated. As shown in FIG. 8A, it is assumed that a thrombus 26 is formed inside the blood vessel 25 and blood flows in the blood vessel inner region 27 in the direction indicated by the arrow in the figure. A blood vessel peripheral tissue 28 exists above and below the blood vessel 25, and a broken line 29 in the figure is a region of interest (ROI).

  The blood vessel 25, the thrombus 26, and the blood vessel peripheral tissue 28 maintain the form before and after the compression by the probe 3, and the displacement with respect to the compression is a collective behavior, and the displacement amount is relatively small. Therefore, the variation of the correlation value is reduced. On the other hand, since the blood vessel inner region 27 is only flowing with blood, the shape cannot be maintained before and after compression, and the displacement is large due to the influence of blood flow, so that a correlation calculation error occurs and the correlation value becomes random. As a result, the variation of the correlation value increases.

  FIG. 8B is a schematic diagram illustrating a boundary image generated and imaged. As described above, the boundary image 30 is generated between the blood vessel inner region 27 having a large correlation value variation and the blood vessel 25 and the thrombus 26 having a small correlation value variation.

  As described above, in this embodiment, the correlation of each measurement point is taken between a pair of RF signal frame data, and the variation of the correlation value is differentiated in order to distinguish the region that changes rapidly and the stable region within the frame data acquisition interval. Since the target part is automatically traced using, for example, blood flow is intense and the amount of displacement cannot be obtained, and even in situations where elasticity information is not obtained, it can be stably between different tissues. A boundary image can be generated.

  As described above, not only the boundary image of the target site such as a lesion site is generated based on the variation of the correlation value of each measurement point, but also the correlation value itself is binarized by a set threshold, for example. It is also possible to generate a boundary image based on Further, the boundary image can be generated based on the displacement amount calculated by the displacement measuring unit 9 and the variation of the displacement amount.

  In the above description, the example in which the correlation value and the displacement amount are calculated by the one-dimensional correlation processing along the compression direction by the probe 3 is not limited to this. Correlation processing can be performed to obtain correlation values, displacement amounts, or variations thereof.

  FIG. 9 is a diagram illustrating an example of generating a combined trace image by combining boundary trace frame data obtained under two different conditions. FIG. 9A is a diagram illustrating an example of the boundary image 30 generated based on the variation of the correlation value obtained by performing the correlation process in the one-dimensional direction along the compression direction, for example. FIG. 9B is a diagram illustrating an example of the boundary image 30 generated based on the variation in the amount of displacement obtained by performing the correlation process in the direction perpendicular to the compression direction. In this figure, a diagram 31 schematically represents a site where a thrombus actually exists.

  FIG. 9C is a diagram showing an example of a combined trace image obtained by tracing a region satisfying either one of these images. As the synthetic trace method, not only a method of tracing a region satisfying one of the two conditions as shown here but a method of tracing a region satisfying both conditions may be used. In addition, although the synthesis under two conditions is shown here, the present invention is not limited to this, and it may be synthesized with a boundary image obtained under another condition, and under which condition the image is synthesized Can be set as appropriate.

  Thus, by combining the images under a plurality of conditions, the boundary image 30 displayed on the image display 14 is approximated to the actual thrombus site, so that the accuracy can be improved.

  In this embodiment, elasticity information is acquired by the displacement measurement unit 9, the strain amount and elasticity modulus calculation circuit 11, and the like. FIG. 10 shows an example of generating a composite image using a boundary image and an elasticity image. FIG. FIG. 10A schematically shows a state in which a boundary image is superimposed on a B-mode image. FIG. 10B schematically shows a state in which an elastic image is superimposed on a B-mode image.

  Then, by combining these two figures, as shown in FIG. 10C, it is also possible to obtain a composite image in which the elastic image is superimposed only in a portion corresponding to the area traced by the boundary image 30. As described above, the ultrasonic diagnostic apparatus of the present invention can generate a boundary image and display it appropriately in combination with an ultrasonic image including an ultrasonic tomographic image such as a B-mode image and an elastic image.

  In the present embodiment, an example is described in which measurement is performed while pressing the subject with the probe 3, elastic frame data is acquired by the strain amount and elastic modulus calculation circuit 11 and the like, and an elastic image is also generated. However, these are not essential. For example, when pressure changes with pulsation as in the blood vessel described above, or when pressure fluctuations occur with breathing, the tissue is displaced according to the pressure fluctuations, so external compression is not required. Can also generate boundary images.

  In the present embodiment, an example in which a diagnosis target is a blood vessel or a thrombus formed inside the blood vessel has been described. However, the present invention is not limited to this, and the present invention can be applied to a body cavity such as the large intestine, small intestine, and esophagus. It can also be applied to organizations.

  The selection of the pair of RF signal frame data may be continuous data in consideration of the frame rate or the like, or may be data separated by a certain interval, and can be selected as appropriate. In addition, the boundary image can be displayed in real time in a series of ultrasonic diagnostic flows, or the RF signal frame data is temporarily stored in a memory or the like, and is generated and displayed offline. Is also possible.

  In addition, a specific hue can be assigned to the boundary image, a display such as a “boundary image” can be displayed while pointing the relevant part with an arrow, etc., and the examiner can grasp the boundary between different tissues at a glance. It is possible to perform display suitable for diagnosis.

1 is a block diagram showing an embodiment of an ultrasonic diagnostic apparatus of the present invention. It is a figure which shows the structure of a probe. It is a figure explaining the method of the compression with respect to a subject. It is a figure explaining a displacement measurement part, a boundary part detection part, distortion, and an elasticity modulus calculation circuit. It is a figure explaining a color scan converter. It is a histogram figure for demonstrating a standard deviation or dispersion | distribution. It is a figure which shows the example which binarized the dispersion | variation in the correlation value and implemented the automatic trace. (A) is a schematic diagram of a tomographic region in a state where no boundary image is generated, and (B) is a schematic diagram showing a state in which the boundary image is generated and imaged. It is a figure which shows the example which synthesize | combines the boundary trace frame data obtained on two different conditions, and produces | generates a synthetic | combination trace image. It is a figure which shows the example which produces | generates a synthesized image using a boundary image and an elasticity image.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ultrasonic transmission / reception control circuit 2 Transmission circuit 3 Probe 4 Reception circuit 5 Phased addition circuit 6 Signal processing part 7 Black-and-white scan converter 8 RF signal frame data selection part 9 Displacement measurement part 10 Boundary part detection part 11 Strain amount and elasticity Rate calculation circuit 12 Color scan converter 13 Switching adder 14 Image display 15 Control unit 16 Keyboard 18 Subject 20 Ultrasound diagnostic device 25 Blood vessel 26 Thrombus 27 Blood vessel internal region 28 Blood vessel peripheral tissue 30 Boundary image

Claims (9)

Based on ultrasonic tomographic data measured by repeatedly transmitting and receiving ultrasonic waves to and from the subject, means for generating an ultrasonic image of the tissue in the tomographic region of the subject, and a display for displaying the ultrasonic image And an ultrasonic diagnostic apparatus comprising:
A correlation value of the ultrasonic tomographic data at a plurality of measurement points of the tomographic region of the subject is obtained based on a pair of the ultrasonic tomographic data having different acquisition times, and a boundary image between the tissues is obtained based on the correlation value. An ultrasonic diagnostic apparatus generated and displayed on the display unit together with the ultrasonic image. The correlation value of the ultrasonic tomographic data at the plurality of measurement points is an autocorrelation value obtained based on a correlation process in a one-dimensional direction or a two-dimensional direction of a pair of the ultrasonic tomographic data having different acquisition times. The ultrasonic diagnostic apparatus according to claim 1, wherein the apparatus is an ultrasonic diagnostic apparatus. The boundary image is a part where at least one of the correlation value at each measurement point and the variation of the correlation value at each measurement point is compared with a set threshold value for each measurement point, and is different from the adjacent measurement points. The ultrasonic diagnostic apparatus according to claim 1, wherein: The ultrasonic wave according to claim 3, wherein the variation in the correlation value is one of a standard deviation and a variance between a correlation value at each measurement point and a correlation value at measurement points around the measurement point. Diagnostic device. The ultrasonic image is an ultrasonic tomographic image or / and an elastic image of a tomographic site of the subject, and the elastic image has different acquisition times measured in the process of changing the pressure applied to the tissue of the subject. The image is generated based on the displacement of the ultrasonic tomographic data obtained at a plurality of measurement points of the tomographic region of the subject based on the pair of ultrasonic tomographic data. Item 2. The ultrasonic diagnostic apparatus according to Item 1. At least one of the displacement at each measurement point and the variation of the displacement at each measurement point is classified by comparing with a set threshold value for each measurement point, and the boundary image is imaged at a location different from the adjacent measurement point. The ultrasonic diagnostic apparatus according to claim 5, wherein the ultrasonic diagnostic apparatus is displayed on the display unit. The ultrasonic diagnostic apparatus according to claim 6, wherein the variation in displacement is one of a standard deviation and a variance between a displacement at each measurement point and a displacement at a measurement point around the measurement point. The ultrasonic diagnostic apparatus according to claim 6, wherein the elasticity image is displayed only on one of the plurality of measurement points that is divided by comparison with a set threshold value of the plurality of measurement points. The tissue of the subject is a blood vessel, and a boundary image of a boundary portion between a blood flow site in the blood vessel and a lesion site formed in the blood vessel is generated. An ultrasonic diagnostic apparatus according to 1.

Images