JP2009005829A - Ultrasonic diagnostic apparatus and processing program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a display allowing tendencies of a plurality of velocity vectors obtained with regard to bloodstream in an organism to be recognized and to be quantitatively analyzed. <P>SOLUTION: A reference image 100A is constituted of a two-dimensional tomographic image 106A and a vector image 108A. The vector image 108A is constituted of a plurality of vectors 110 obtained with respect to a plurality of measurement points. A scatter diagram image 102A is formed by mapping terminal points of the respective vectors while by making starting points of the respective vectors coincide with one another. A distribution of a group of terminal points 119A in the scatter diagram image 102A is quantitatively analyzed and thereby an evaluation value is obtained. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an ultrasonic diagnostic apparatus and a processing program, and more particularly to display and evaluation of a velocity vector measured for a moving body in a living body.

  The ultrasonic diagnostic apparatus has a function of displaying an image of blood flow as an in-vivo moving body. In general, a blood flow image is a color image, which is synthesized and displayed on a two-dimensional tissue image (B-mode tomographic image) as a black and white image. The blood flow image is conventionally called a color Doppler image or a color flow mapping image. As described in Patent Document 1, in a typical blood flow image, for example, blood that flows in a direction approaching the ultrasound probe is expressed in red, and blood that flows in a direction away from the ultrasound probe. Is expressed in blue. The speed in each direction is associated with the luminance. Blood flow that moves at high speed is expressed with high brightness, and blood flow that moves at low speed is expressed with low brightness. Note that dispersion information may be displayed together with the speed information, and in this case, the magnitude of the dispersion is expressed by a change in hue. A conventional blood flow image is an image that simply displays the velocity distribution of the blood flow on the scanning plane in color, and represents only the velocity component in the beam direction, so it recognizes the actual flow from the blood flow image. It is very difficult to do.

  Several techniques for calculating a two-dimensional velocity vector for blood flow have already been proposed (Patent Documents 2-8). Patent Documents 2-4 describe calculating a two-dimensional velocity vector (or information corresponding thereto) from two velocity components obtained on two beams having different deflection angles. Patent Documents 5-6 describe that a two-dimensional velocity vector is calculated from two velocity components obtained on two beams that intersect on a target. Patent Document 7 describes that a two-dimensional velocity vector is calculated from a beam direction velocity component distributed on a scanning plane based on a certain assumption about the flow. Patent Document 8 describes that two-dimensional vector information is displayed using a change in hue. An unpublished prior application related to the present application is Japanese Patent Application No. 2006-256743.

JP 59-20820 A Japanese Patent Laid-Open No. 62-152436 Japanese Patent Laid-Open No. 62-152437 JP-A-3-4842 JP-A-3-47241 JP-A-7-204204 JP 2005-110939 A JP 62-152439 A

  It is also possible to spatially express a plurality of velocity vectors obtained for a plurality of measurement points using graphic elements such as arrows. However, it is difficult to grasp the overall trend of the flow from such an image. In particular, it is difficult to quantitatively grasp the spread of the flow.

  An object of the present invention is to provide an image capable of intuitively recognizing a flow state based on a plurality of velocity vectors.

  Another object of the present invention is to make it possible to quantitatively evaluate the flow state based on a plurality of velocity vectors.

  The present invention relates to a velocity vector calculation means for obtaining a plurality of velocity vectors for a plurality of measurement points in a transmission / reception region based on data obtained by transmission / reception of ultrasonic waves, and a plurality of obtained for the plurality of measurement points. A means for creating a scatter diagram based on the velocity vector of the scatter diagram, wherein the scatter diagram is created by mapping the end points of the respective velocity vectors on the coordinate system while matching the start points of the respective velocity vectors And an ultrasonic diagnostic apparatus.

  According to the above configuration, for example, when a plurality of velocity vectors are obtained for a plurality of measurement points set in the bloodstream, a scatter diagram is created based on them. The scatter diagram corresponds to an image in which the start points of a plurality of velocity vectors are matched and the end points of the plurality of velocity vectors are mapped on the coordinate system. From the contents of the scatter diagram, it is possible to intuitively and easily grasp the tendency of the flow, in particular, the spread of the flow and the strength of the flow. The velocity vector is preferably a two-dimensional velocity vector, but may be a three-dimensional velocity vector. In that case, the end point of each velocity vector is mapped in the three-dimensional space. The velocity vector may be a motion vector that represents information corresponding to the velocity information. The scatter diagram is preferably configured as a two-dimensional graph, and the contents are updated for each time phase. The scatter diagram may be updated simultaneously with the measurement, that is, in real time. In that case, the scatter diagram is a moving image. However, a scatter diagram of a specific time phase may be created, or a scatter diagram corresponding to a specific period may be created. You may make it create a scatter diagram based on the data stored in the memory | storage part.

  Desirably, it includes a region of interest setting means for setting a region of interest in the transmission / reception region, and the scatter diagram is created based on a plurality of velocity vectors for a plurality of measurement points in the region of interest. The region of interest is set manually or automatically. The region of interest is set, for example, in the bloodstream of the heart. It is desirable to set the region of interest so as not to include the heart wall. The position and size of the region of interest may be dynamically varied as the heart moves.

  Preferably, display processing means for forming a display image having a reference image representing the transmission / reception region and a scatter diagram image representing the scatter diagram is included. Preferably, the reference image is a composite image including a tomographic image representing a tissue in the transmission / reception region and a velocity vector image representing the plurality of velocity vectors. If the reference image is displayed, the data that is the basis of the scatter diagram can be recognized. In addition, it becomes easy to simultaneously grasp the spatial grasp of the flow and the overall tendency of the vector group.

  Preferably, flow evaluation means for analyzing the distribution state of the end point group in the scatter diagram is included. Preferably, the flow evaluation means is evaluated based on a main direction calculation means for calculating a main direction of the flow in the scatter diagram and a number of effective end points belonging to a range of interest centered on the main direction on the scatter diagram. Evaluation value calculating means for calculating a value. Various methods can be employed as the flow evaluation method, but it is desirable to employ a method that can quantitatively grasp the deviation of the end point distribution. If the main direction is defined, it becomes easy to quantitatively grasp the direction and state of the flow in relation to the overall trend of the flow.

  A program according to the present invention is a processing program that is executed in a computer and processes a plurality of velocity vectors obtained for a plurality of measurement points in an ultrasonic transmission / reception region, and is distributed based on the plurality of velocity vectors. A function of creating a diagram, and a function of calculating an evaluation value by analyzing the contents of the scatter diagram, wherein the scatter diagram matches the start points of the velocity vectors. It is created by mapping the end points on a predetermined coordinate system, and the evaluation value represents a distribution state of a plurality of end points on the scatter diagram. This program is read and executed by the ultrasonic diagnostic apparatus, or is read and executed by the computer.

  As described above, according to the present invention, it is possible to provide an image in which the flow state can be intuitively recognized based on a plurality of velocity vectors. Alternatively, according to the present invention, the flow state can be quantitatively evaluated based on a plurality of velocity vectors.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the drawings.

  FIG. 1 is a block diagram showing the overall configuration of the ultrasonic diagnostic apparatus according to this embodiment. As will be described in detail below, this ultrasonic diagnostic apparatus has a function of forming a scatter diagram image that can express the state of blood flow in a living body.

  The probe 10 has an array transducer. The array transducer is composed of a plurality of transducer elements, and an ultrasonic beam is formed by the array transducer. The ultrasonic beam is scanned electronically. As an electronic scanning method, electronic linear scanning, electronic sector scanning, and the like are known. A 2D array transducer may be provided for the probe 10, and a 3D echo data capturing space may be formed by the 2D array transducer. The probe 10 is used in contact with the surface of a living body in the present embodiment, but may be used by being inserted into a body cavity. As will be described later, in order to measure a velocity vector as motion information, a plurality of probes or a plurality of array transducers can be used simultaneously as necessary.

  The transmission unit 12 functions as a transmission beam former. The transmission unit 12 supplies a plurality of transmission signals to the plurality of vibration elements. As a result, a transmission beam transmitted from the array transducer is formed. Reflected waves from the living body are received by a plurality of vibration elements, whereby a plurality of received signals are output from the probe 10 to the receiving unit 14. In the present embodiment, the organ to be subjected to ultrasonic diagnosis is the heart (for example, the left ventricle). The reflected wave from the living body includes a Doppler shift frequency component corresponding to the blood flow velocity.

  The reception unit 14 functions as a reception beam former. A phasing addition process is performed on a plurality of reception signals input to the reception unit 14, thereby forming a reception beam electronically. The reception signals corresponding to the respective reception beams are output to the tomographic image forming unit 16 and the vector calculation unit 18 in the present embodiment. A plurality of reception beams may be simultaneously formed for one transmission beam.

  The tomographic image forming unit 16 generates a tomographic image as a B-mode image based on echo data groups (that is, a plurality of received signals corresponding to a plurality of ultrasonic beams) on the scanning surface formed by electronic scanning of the ultrasonic beam. Form. The image data is sent to the display processing unit 22. The tomographic image forming unit 16 includes a module such as a digital scan converter (DSC).

  On the other hand, the vector calculation unit 18 calculates a two-dimensional velocity vector for each point (each coordinate) on the scanning plane based on the reception signal output from the reception unit 14. In this embodiment, the vector calculation unit 18 converts a received signal into a complex signal by quadrature detection processing, an autocorrelator that performs an autocorrelation operation on the complex signal, and a beam direction velocity component from the autocorrelation result. It includes a speed calculator for calculating. Furthermore, for each position (coordinate as a sample point) on the scanning plane, a vector calculator that calculates the beam direction and two velocity components orthogonal to the beam as a two-dimensional velocity vector is provided. A plurality of two-dimensional velocity vectors calculated for a plurality of positions on the scanning plane constitute a vector matrix (vector set or vector array). This vector matrix is generated for each frame. The vector calculation unit 18 also includes a DSC and other modules. In order to calculate the velocity component, it is also possible to use an FFT calculator and other calculators. All or some of the functions of the vector calculation unit 18 may be realized as software functions.

  The two-dimensional velocity vector can be calculated using various methods such as the method described in Patent Documents 1-7 and the inter-frame pattern matching method. Instead of the two-dimensional velocity vector, a three-dimensional velocity vector may be calculated. Further, instead of the velocity vector, other motion information indicating the direction and magnitude of the flow may be calculated. Furthermore, exercise information may be obtained from echo information (luminance information) of the blood portion without using Doppler information. For example, between two tomographic image frames, pattern matching processing may be applied to a plurality of sample points in the blood flow portion, and temporal changes of individual sample points may be observed for each frame.

  As described above, the vector image forming unit 24 is a module that forms a vector image representing a plurality of two-dimensional velocity vectors obtained for a plurality of positions (measurement points) on the scanning plane. A specific example thereof will be described later with reference to FIG. 2, but each two-dimensional velocity vector is displayed as a graphic element such as an arrow in the present embodiment on the vector image. Image data representing the vector image is output to the display processing unit 22.

  The scatter diagram forming unit 26 is a module that forms a scatter diagram image based on a plurality of two-dimensional velocity vectors obtained for a plurality of measurement points. A specific example will be described later with reference to FIG. The scatter diagram is created by mapping the end points of the two-dimensional velocity vectors while matching the start points of the two-dimensional velocity vectors. The image data is output to the display processing unit 22.

  In this embodiment, the flow evaluation unit 28 includes a main direction calculation unit 30 and an evaluation value calculation unit 32. The flow evaluation unit 28 is a module that analyzes and evaluates the contents of the scatter diagram described above. Specifically, the flow evaluation unit 28 calculates the main direction of the flow from a plurality of two-dimensional velocity vectors obtained for a plurality of measurement points, and The flow evaluation value is calculated based on the main direction. The evaluation value that is the evaluation result is output to the display processing unit 22. The flow evaluation will be described with reference to FIGS.

The display processing unit 22 is a unit that generates a display image to be displayed on a display (not shown), and forms an image shown in FIG. Specifically, the display processing unit 22 has a function of generating a display image having a reference image, a scatter diagram image, and an electrocardiogram waveform.
Here, the reference image is an image formed by combining a two-dimensional tomographic image and a vector image representing a plurality of two-dimensional velocity vectors.

  The control unit 34 performs operation control of each configuration shown in FIG. 1, and the control unit 34 includes a CPU and an operation program. Incidentally, each module such as the vector calculation unit 18, the vector image forming unit 24, the scatter diagram forming unit 26, and the flow evaluation unit 28 may be substantially realized as a software function. The operation panel 36 includes a keyboard and a trackball, and operating conditions can be set using the operation panel 36. In the present embodiment, the region of interest (ROI) can be set by the user using the operation panel 36. The region of interest is set as a common region for each frame, or is set individually for each frame.

  The biological signal measuring unit 38 is a unit that measures an electrocardiographic signal as a biological signal. The electrocardiographic signal is sent to the control unit 34 and also sent to the display processing unit 22.

  FIG. 2 shows an example of a display image displayed on the display. Reference numeral 100 represents a reference image, reference numeral 102 represents a scatter diagram image 102, and reference numeral 104 represents an electrocardiographic waveform. As will be described later, the reference image 100 is an image obtained by combining a two-dimensional tomographic image and a vector image. In FIG. 2, the reference image 100 includes a closed curve representing the region of interest. In the illustrated example, a region of interest is set in the left chamber of the heart. It is desirable to set the region of interest in the blood flow part, that is, to set the region of interest so that the heart wall or the like is not included. The region of interest can be set as a fixed region, or can be set as a region that moves with the translational motion of the heart.

  In the scatter diagram 102, the horizontal axis and the vertical axis each represent the magnitude of the speed. The scatter diagram image 102 can be constructed by aligning the start points of a plurality of two-dimensional velocity vectors with a common origin and mapping the end points on the coordinate system shown in FIG. The plurality of mapped points correspond to the plurality of measurement points measured in the region of interest described above, and specifically represent the end points of the plurality of two-dimensional velocity vectors obtained for those measurement points. ing. By observing the form of the scatter diagram in the scatter diagram image 102, the overall trend of the flow can be grasped intuitively and easily. For example, it is possible to easily grasp the flow state regarding the amount of blood flowing into the left ventricle or the amount of bleeding, for example, whether or not the flow is wide. In addition, when there is a disease, it appears as a form of a scatter diagram. Therefore, it is possible to evaluate the content and degree of the disease from the form of the scatter diagram. The evaluation method of the scatter diagram will be described later.

  FIG. 3 shows a reference image 100A and a scatter diagram image 102A in the left ventricular diastole. As described above, the reference image 100A is composed of the two-dimensional tomographic image 106A and the vector image 108A representing a plurality of two-dimensional velocity vectors. The vector image 108A is composed of a plurality of graphics vectors, and each vector 110 has a start point 111 and an end point 112. The end point 112 is represented as a round mark in the illustrated example, but it corresponds to an arrow. The length of the vector 110 corresponds to the flow speed, and the direction of the vector 110 corresponds to the flow direction.

  A scatter diagram image 102A is obtained by matching the end points of the plurality of vectors with the origin 114 and mapping the end points of the respective vectors. The scatter diagram image 112A is an end point distribution diagram as a scatter diagram, and includes an end point group 119A. The end point group 119A is constituted by the individual end points 120 as described above. The horizontal axis 116 and the vertical axis 118 represent the magnitude of the speed.

  The electrocardiogram waveform 104A represents a periodic movement of the heart, and a marker 122 representing the time or time phase of the analyzed frame is displayed on the electrocardiogram waveform 104A.

  As shown in FIG. 3, in the diastole, blood flow flows strongly in a certain direction, and in the example shown in FIG. 3, the spread of the flow is not so large. In addition, there is not much backflow.

  On the other hand, FIG. 4 shows a reference image 100B and a scatter diagram image 102B in the systole. The reference image 100B is formed by combining the two-dimensional tomographic image 106B and the vector image 108B as described above. The scatter diagram image 102B has an end point group 119B. As shown in the figure, a flow occurs along a certain direction, and the spread of the flow is not so large.

  In order to quantitatively analyze the above scatter diagram or a plurality of two-dimensional velocity vectors, the flow evaluation unit shown in FIG. 1 is provided. Below, the processing content of the main direction calculating part and evaluation value calculating part which the flow evaluation part has is demonstrated.

  In FIG. 5, in S101, the number N of vectors in the region of interest is calculated. In S102, the main direction is obtained by adding all the vectors in the region of interest. In S103, α / 2 is set as the angle in the positive direction and the angle in the negative direction around the determined main direction, that is, the angle range α around the main direction is set, and the number M of vectors contained therein is calculated. Is done. In S104, the flow evaluation value E is obtained by M / N. In other words, the flow can be evaluated by calculating the ratio of the number of vectors included in a certain angle range with the main direction of the flow as the center to the total number of vectors. For example, in the example shown in FIG. 6, the main direction 122A is obtained from the end point group 119A, the number of vectors within the angle range α centered on it is obtained, and the evaluation value is calculated therefrom. In the example shown in FIG. 6, a large value is obtained as the evaluation value E because many vectors are included in the angle range α. On the other hand, in the example shown in FIG. 7, the main direction 122C similar to the main direction 122A is obtained for the end point group 119C, but there are not many vectors in the angle range α centered on the main direction 122C. As a result, a small value is obtained as the evaluation value E. Therefore, it is possible to quantitatively evaluate the flow state by evaluating the scatter diagram in this way.

  As shown in FIGS. 6 and 7, since the vector length is obtained for the main directions 122A and 122C, the angle range may be dynamically changed using the information. Further, the end point included in the angle range may be differentiated from other end points by performing a coloring process.

  Obtain the scatter diagram shown in Figure 2 etc. for a large number of subjects, categorize and accumulate disease cases, and evaluate the possibility of disease for each subject using pattern matching methods etc. Is also possible. Therefore, the method according to the present invention brings about a clinically beneficial effect. For example, there is a possibility that a disease that was difficult to diagnose by simply observing a conventional two-dimensional color flow mapping image can be easily diagnosed from a scatter diagram.

1 is a block diagram showing an overall configuration of an ultrasonic diagnostic apparatus according to the present invention. It is a figure which shows an example of the display image displayed on a display. It is a figure which shows an example of a reference image and a scatter diagram image. It is a figure which shows the other example of a reference image and a scatter diagram image. It is a flowchart for demonstrating the method of quantitative analysis of a scatter diagram. It is a figure for demonstrating an example of the quantitative analysis of a scatter diagram. It is a figure for showing other examples of quantitative analysis of a scatter diagram.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Probe, 18 vector calculating part, 22 Display processing part, 24 Vector image forming part, 26 Scatter figure forming part, 28 Flow evaluation part, 30 Main direction calculating part, 32 Evaluation value calculating part

Claims (7)

Based on data obtained by transmission / reception of ultrasonic waves, velocity vector calculation means for obtaining a plurality of velocity vectors for a plurality of measurement points in the transmission / reception region
A means for creating a scatter diagram based on a plurality of velocity vectors obtained for the plurality of measurement points, mapping the end points of the respective velocity vectors on the coordinate system while matching the starting points of the respective velocity vectors. A scatter diagram creating means for creating the scatter diagram by:
An ultrasonic diagnostic apparatus comprising: The apparatus of claim 1.
A region of interest setting means for setting a region of interest in the transmission / reception region;
The ultrasonic diagnostic apparatus, wherein the scatter diagram is created based on a plurality of velocity vectors for a plurality of measurement points in the region of interest. The apparatus according to claim 1 or 2,
An ultrasonic diagnostic apparatus comprising: display processing means for forming a display image having a reference image representing the transmission / reception region and a scatter diagram image representing the scatter diagram. The apparatus of claim 3.
The ultrasonic diagnostic apparatus according to claim 1, wherein the reference image is a composite image including a tomographic image representing a tissue in the transmission / reception region and a velocity vector image representing the plurality of velocity vectors. The device according to any one of claims 1 to 4,
An ultrasonic diagnostic apparatus comprising flow evaluation means for analyzing a distribution state of end points in the scatter diagram. The apparatus of claim 5.
The flow evaluation means includes
Main direction calculating means for calculating the main direction of the flow in the scatter diagram;
An evaluation value calculating means for calculating an evaluation value based on the number of effective end points belonging to the attention range centered on the main direction on the scatter diagram;
An ultrasonic diagnostic apparatus comprising: A processing program that is executed in a computer and processes a plurality of velocity vectors obtained for a plurality of measurement points in an ultrasonic transmission / reception region,
A function of creating a scatter diagram based on the plurality of velocity vectors;
A function of analyzing the contents of the scatter diagram and calculating an evaluation value;
Including
The scatter diagram is created by mapping the end point of each speed vector on a predetermined coordinate system while matching the start point of each speed vector,
The evaluation value represents a distribution state of a plurality of end points on the scatter diagram.
A processing program characterized by that.