JP2009082181A - Ultrasonograph - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an improved technology for correcting dislocation of a contrast image. <P>SOLUTION: A pattern matching part calculates a moving distance between time phases of an image part corresponding to its ROI34 with respective ROI34 based on image data of a B mode image 30 formed over a plurality of time phases. When the moving distance of the two ROI34 is successively calculated with respective time phases, while correcting the dislocation of the image between the time phases by a correction quantity corresponding to the calculated moving distance, the image data of a capture image 40 is formed. Thus, blurring of the capture image 40 is restrained by using the B mode image 30, and a locus of a blood vessel 42 becomes clear, and a structure of the fine blood vessel 42 can be observed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an ultrasonic diagnostic apparatus, and more particularly to an ultrasonic diagnostic apparatus that forms a contrast image using a contrast agent.

  A contrast agent containing bubbles or the like becomes a suitable reflector of ultrasound, and is used for forming an ultrasound contrast image. For example, by imaging a contrast agent administered into a blood vessel or the like, it is possible to form a contrast image that clearly shows blood flow or the like as compared with a normal ultrasonic diagnosis that does not use a contrast agent.

  In addition, there is known a method of projecting a state in which a contrast medium flows through a subject by destroying bubbles contained in the contrast medium with ultrasonic waves. In other words, first, the contrast agent is observed using ultrasonic waves with a low sound pressure that does not destroy the contrast agent (bubbles), and then, the contrast agent (bubbles) in the observation region is switched to ultrasonic waves with a high sound pressure. This method is called a recirculation method in which the contrast medium flows into the observation region using ultrasonic waves with a low sound pressure again (see Patent Document 1).

  Furthermore, in the image obtained by the reperfusion method, the maximum value for displaying the trajectory of the flow of the contrast medium flowing in the blood vessel or the like by holding the maximum value among the luminance values of each pixel changing for each time phase A technique called a holding method is also known (see Patent Document 1).

JP 2006-247122 A

  When displaying the trajectory of the contrast agent flow by combining the recirculation method and the maximum value holding method, if the subject moves due to, for example, breathing within the period during which the trajectory is displayed, the trajectory may be blurred. It becomes a clear image.

  Incidentally, it is conceivable to perform correlation processing or the like on a plurality of time phase contrast images and to correct the motion while tracking the motion (deviation) of the image between the time phases. However, in the contrast image, the contrast medium to be observed moves, and it is not easy to track the movement of only the tissue other than the contrast medium. Further, if the movement of the contrast agent is corrected, the original flow of the contrast agent cannot be expressed.

  Under such circumstances, the inventor of the present application has repeatedly researched and developed a technique for correcting the shift of the contrast image.

  The present invention has been made in the course of its research and development, and an object thereof is to provide an improved technique for correcting the shift of contrast images.

  In order to achieve the above object, an ultrasonic diagnostic apparatus according to a preferred embodiment of the present invention includes a probe for transmitting and receiving ultrasonic waves to a subject to which a contrast agent is administered, and within the contrast time period by controlling the probe. A plurality of reference image data for a tissue in the subject based on the transmission / reception unit that obtains the received signal from the subject over a plurality of time phases and the received signal acquired within the contrast time Between the reference image forming unit formed over the time phases and the time phases of the image portions corresponding to the reference regions set in the reference image based on the image data of the reference images formed over the plurality of time phases Based on a received signal acquired within the contrast time, and a moving amount calculation unit that calculates a moving amount at the time, the dose is corrected by the correction amount according to the moving amount, and is applied to the subject while correcting the image shift between the time phases. Targeted contrast media It characterized by having a a contrast image forming unit that forms over a plurality of time phases image data of a contrast image.

  According to the above aspect, since the amount of movement between phases is calculated using the reference image, it is easier to move the tissue other than the contrast agent as compared to the case of calculating the amount of movement using the contrast image. It is possible to trace, and it is possible to represent the flow of the original contrast agent. Incidentally, according to the above aspect, since the movement amount is calculated using the reference region set in the reference image, for example, the calculation amount is reduced as compared with the case where the correlation calculation is performed on the entire reference image. .

  In a preferred aspect, the contrast image forming unit forms image data of a contrast image showing how the administered contrast agent circulates in the subject based on echo data obtained for each time phase from the received signal. It is characterized by doing.

  In a desirable mode, the contrast image forming unit selects, for each time phase, specific echo data from a plurality of time phase echo data corresponding to the same image position obtained up to that time phase, and By forming pixel data of the image position from specific echo data, image data of the contrast image composed of a plurality of pixel data is formed.

  In a preferred aspect, the reference image forming unit forms image data of a B-mode image that is the reference image based on echo data corresponding to a fundamental wave component included in a received signal, and the contrast image forming unit includes: The image data of the contrast image is formed based on echo data corresponding to the harmonic component included in the received signal.

  In a preferred aspect, the transmitting / receiving unit forms a frame by scanning an ultrasonic beam, and alternately obtains a reception signal for a reference image and a reception signal for a contrast image in units of frames or reception beams. Features.

  In a preferred aspect, two or more reference regions are set in the reference image. In a preferred aspect, the reference region is set so as to include a characteristic part such as a blood vessel wall or a diaphragm in a reference image.

  The present invention provides an improved technique for correcting a contrast image shift. For example, according to a preferred aspect of the present invention, since the movement amount between the time phases is calculated using the reference image, the tissue other than the contrast agent is compared with the case where the movement amount is calculated using the contrast image. It is possible to easily track movements such as the above, and to express the flow of the original contrast agent.

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

  FIG. 1 shows a preferred embodiment of an ultrasonic diagnostic apparatus according to the present invention, and FIG. 1 is a functional block diagram showing the overall configuration thereof. The ultrasonic diagnostic apparatus shown in FIG. 1 is suitable for forming an image using a contrast agent including a contrast bubble (microbubbles such as microbubbles and nanobubbles). The contrast agent is administered to a diagnostic site such as a blood vessel or a tumor in a living body. Then, a state in which the contrast agent administered into the living body flows through the blood vessel or the like is imaged.

  The probe 10 transmits / receives ultrasonic waves to / from a living body to which a contrast medium is administered. The probe 10 includes a plurality of vibration elements that transmit and receive ultrasonic waves. The plurality of vibration elements are transmission-controlled by the transmission / reception unit 12 and the transmission beam is scanned. In addition, a plurality of vibration elements receive ultrasonic waves reflected from the living body, and signals obtained thereby are output to the transmission / reception unit 12, and the transmission / reception unit 12 forms a reception beam to acquire a reception signal.

  The probe 10 is, for example, a convex electronic scan probe, and an ultrasonic beam (a transmission beam and a reception beam) is electronically scanned in a fan shape in a two-dimensional plane. Of course, as the probe 10, a linear electronic scan probe or another electronic scan probe may be used, or a probe that mechanically scans the beam may be used. Furthermore, a three-dimensional probe that scans an ultrasonic beam three-dimensionally may be used.

  The transmitter / receiver 12 forms, for example, a single frame composed of a plurality of reception beams by scanning an ultrasonic beam in a fan shape, and forms a plurality of frames over a plurality of time phases. For example, the transmission / reception unit 12 alternately acquires a reception signal for a B-mode image and a reception signal for a contrast mode image, which will be described later, in units of frames. Of course, the reception signal for the B mode image and the reception signal for the contrast mode image may be alternately obtained in units of reception beams, or the same reception signal may be used for forming the B mode image and the contrast mode image. .

  The B-mode image processing unit 14 forms image data of a B-mode image based on the reception signal obtained for each reception beam, that is, for each scanning direction. The B-mode image processing unit 14 extracts a fundamental wave component included in the received signal, and forms image data from echo data corresponding to the fundamental wave component. As a result, image data of a B-mode image mainly for tissue in the living body (for example, including a blood vessel wall or a diaphragm) is formed. The image data is formed for each time phase over a plurality of time phases.

  The contrast mode image processing unit 16 forms image data of a contrast mode image based on the reception signal obtained for each received beam, that is, for each scanning direction. The contrast mode image processing unit 16 extracts a harmonic component (for example, a second harmonic component) included in the received signal, and forms image data from echo data corresponding to the harmonic component. Since the harmonic component mainly includes the reflection component from the contrast agent (bubble), the image data of the contrast mode image mainly showing the contrast agent clearly is obtained by using the harmonic component. It is formed. The image data is formed for each time phase over a plurality of time phases.

  The pattern matching unit 18 sets an ROI (region of interest) in the image data of the B mode image formed by the B mode image processing unit 14. Although only one ROI may be used, it is desirable to set a plurality of ROIs. The pattern matching unit 18 calculates, for each ROI, the movement amount between the time phases of the image portion corresponding to the ROI based on the image data formed over a plurality of time phases. The movement amount calculated one after another for each time phase is output to the capture processing unit 20. The processing by the pattern matching unit 18 will be further described later (see FIG. 2).

  The capture processing unit 20 forms a capture image that reflects a state in which the contrast agent flows through the living body, based on a plurality of contrast mode images of a time phase. In order to form a capture image, at the time of disclosure of the capture process, first, image data is formed by the contrast mode image processing unit 16 using ultrasonic waves having a low sound pressure that does not destroy the contrast agent (bubble). The Thereafter, the contrast medium (bubble) in the observation region is destroyed by switching to the high sound pressure ultrasonic wave, and image data is formed by the contrast mode image processing unit 16 again using the low sound pressure ultrasonic wave. .

  The capture processing unit 20 selects the maximum echo data from among a plurality of time phase echo data corresponding to the same image position obtained up to that time phase for each time phase from the time point when the capture processing is disclosed. The maximum echo data is set as pixel data at the image position. The capture processing unit 20 selects the maximum echo data for each of a plurality of image positions to form pixel data at each image position, and forms image data of a captured image composed of the plurality of pixel data.

Since the echo data processed in the capture processing unit 20 is echo data corresponding to the harmonic component, the echo data obtained from the contrast agent is relatively large (high brightness). Therefore, by selecting the largest echo data from a plurality of time-phase echo data corresponding to the same image position and forming pixel data at the image position, an image in which a contrast agent has existed in the past basically The data of the contrast medium is left at the position. Therefore, the captured image formed as described above shows the trajectory through which the contrast agent has passed.
Note that the capture processing unit 20 forms image data of the captured image while correcting the image shift between the time phases by a correction amount corresponding to the movement amount calculated by the pattern matching unit 18. The correction will be described later (see FIG. 2).

  The image data formed in the B-mode image processing unit 14 and the capture processing unit 20 is output to the display image processing unit 24 via the memory 22. The memory 22 functions as a cine memory. That is, the latest time phase image data is successively output to the display image processing unit 24 via the memory 22, and the image data from the latest time phase to a time phase several seconds or several tens of seconds in the past is stored in the memory 22. Remembered.

  The display image processing unit 24 forms a display image based on the image data of the B mode image and the image data of the capture image. For example, a display image in which a B-mode image and a captured image are arranged side by side is formed. Of course, an image in which the B-mode image and the captured image are individually displayed may be formed. The display image formed in the display image processing unit 24 is displayed on a display unit 26 such as a monitor.

  Incidentally, the reception signal obtained from each reception beam formed in the transmission / reception unit 12 corresponds to the scanning coordinate system of the ultrasonic beam. For example, it corresponds to an rθ polar coordinate system expressed by a beam depth r and a beam scanning angle θ. On the other hand, the display image displayed on the display unit 26, that is, the B-mode image and the capture image displayed on the display unit 26 correspond to a coordinate system suitable for display on the display unit 26, for example, an xy orthogonal coordinate system. It is desirable that

  Therefore, for example, the reception signal output from the transmission / reception unit 12 is processed one after another in the subsequent stages while remaining in the rθ polar coordinate system, and the display image processing unit 24 performs coordinate conversion processing from the rθ polar coordinate system to the xy orthogonal coordinate system ( Scan conversion) is executed. Of course, for example, coordinate conversion processing may be executed in the B-mode image processing unit 14 or the contrast-mode image processing unit 16.

  In the present embodiment, correction processing for suppressing blurring (image shift) of the captured image formed in the capture processing unit 20 is executed. The correction process will be described below. In addition, about the part (structure) shown in FIG. 1, the code | symbol of FIG. 1 is utilized in the following description.

  FIG. 2 is a diagram for explaining processing for correcting blurring of a captured image. FIG. 2 illustrates a B-mode image 30 that is an example of an image formed in the B-mode image processing unit 14 and a capture processing unit. A captured image 40 which is an example of an image formed at 20 is shown. The reception signal for the B-mode image 30 and the reception signal for the capture image 40 are obtained alternately in units of frames from the same scanning region. Therefore, the B-mode image 30 and the captured image 40 are images that show the same diagnostic region, and are images that are at substantially the same time.

  The B-mode image 30 is an image formed based on the fundamental wave component included in the received signal, for example, and the B-mode image 30 is mainly compared with tissues in the living body, for example, tissues such as blood vessel walls and diaphragms. It is clearly projected.

  On the other hand, the captured image 40 is an image formed based on, for example, a harmonic component included in the received signal. In the captured image 40, a contrast agent is mainly projected clearly, and the trajectory through which the contrast agent has passed. Is shown. The contrast agent administered into the living body flows in the blood vessel 42 together with blood, for example. Therefore, by clearly projecting the contrast agent, the inside of the blood vessel 42 is clearly projected.

  As described above, the captured image 40 shows the trajectory through which the contrast agent has passed. For example, when blood and a contrast medium flow in the blood vessel 42 from the right side to the left side of the drawing, the trajectory of the contrast medium dynamically extends from the right side to the left side along the flow of the contrast medium. Therefore, the captured image 40 forms a moving image as if the blood vessel 42 gradually grows from the right side to the left side.

  However, if the living body moves due to, for example, breathing within the period in which the trajectory is displayed by the captured image 40, the trajectory is blurred and the image becomes unclear. For example, the image of the blood vessel 42 is blurred. Therefore, in the present embodiment, correction processing for suppressing blurring of the captured image 40 using the B-mode image 30 is executed.

  That is, first, the ROI (region of interest) 34 is set in the B-mode image 30 by the pattern matching unit 18. Although only one ROI 34 may be used, it is desirable to set a plurality of ROIs. For example, two ROIs 34 are set in the B mode image 30. Each ROI 34 may be set automatically by the apparatus, or may be manually set by a user (inspector) at a desired position. Each ROI 34 is desirably provided in a relatively bright image portion. For example, in the case of diagnosis of the abdomen, each ROI 34 is set in the diaphragm or a large blood vessel. The ROI 34 may set the entire B mode image 30.

  Then, the pattern matching unit 18 calculates, for each ROI 34, the amount of movement of the image portion corresponding to the ROI 34 between the time phases based on the image data of the B-mode image 30 formed over a plurality of time phases. . The amount of movement between time phases can be confirmed for each ROI 34 by a pattern matching method.

  For example, the B mode image 30 of the frame (previous frame) in which each ROI 34 is set is compared with the B mode image 30 of the frame (current frame) in which the movement amount is detected, and an image similar to the image portion in each ROI 34 Extract the part from the current frame. Then, from the difference between the position of each ROI 34 in the previous frame and the position of the image part corresponding to each ROI 34 in the current frame, the movement amount of the image part corresponding to each ROI 34 between the previous frame and the current frame is calculated. Calculated.

  Examples of the pattern matching method include known techniques such as a template matching method and a PG matching method. Of course, in this embodiment, other pattern matching techniques may be used.

  When the movement amount of the two ROIs 34 is calculated one after another for each time phase by the pattern matching unit 18, the capture processing unit 20 corrects the image shift between the time phases by the correction amount according to the calculated movement amount. However, the image data of the captured image 40 is formed. For example, the relative positional relationship between the previous frame and the current frame of the B-mode image 30 is adjusted so that image portions corresponding to the same ROI 34 overlap in the previous frame and the current frame. For example, the positional relationship is adjusted by parallel movement or rotational movement of the B-mode image 30 in the image plane.

  The capture processing unit 20 performs the same adjustment as the adjustment of the positional relationship with respect to the B-mode image 30 on the plurality of temporal-phase contrast mode images output from the contrast mode image processing unit 16, and And adjust the relative position of the current frame. In this way, image shift between time phases is corrected for a plurality of time-phase contrast mode images, and blurring of the captured image 40 formed based on the plurality of time-phase contrast mode images is suppressed. As a result, the trajectory of the blood vessel 42 becomes clear, and for example, the structure of the fine blood vessel 42 can be observed. For example, it is possible to clearly show the state of the fine blood vessel 42 constructed in the cancer cell.

  As mentioned above, although preferred embodiment of this invention was described, embodiment mentioned above is only a mere illustration in all the points, and does not limit the scope of the present invention. The present invention includes various modifications without departing from the essence thereof.

1 is a functional block diagram showing an overall configuration of an ultrasonic diagnostic apparatus according to the present invention. It is a figure for demonstrating the process which correct | amends the blur of a captured image.

Explanation of symbols

  10 probe, 12 transmission / reception unit, 14 B-mode image processing unit, 16 contrast mode image processing unit, 18 pattern matching unit, 20 capture processing unit.

Claims (7)

A probe that transmits and receives ultrasound to and from a subject to which a contrast agent is administered;
A transmission / reception unit for acquiring a reception signal from a subject over a plurality of time phases within a contrast time period by controlling a probe;
A reference image forming unit that forms image data of a reference image for a tissue in a subject over a plurality of time phases based on a received signal acquired within the contrast time;
Based on the image data of the reference image formed over a plurality of time phases, a movement amount calculation unit that calculates the movement amount between the time phases of the image portion corresponding to the reference region set in the reference image;
Based on the received signal acquired within the contrast period, an image of a contrast image targeted for the contrast agent administered to the subject while correcting the image shift between the time phases by a correction amount corresponding to the amount of movement. A contrast image forming unit for forming data over a plurality of time phases;
Having
An ultrasonic diagnostic apparatus. The ultrasonic diagnostic apparatus according to claim 1,
The contrast image forming unit forms image data of a contrast image showing how the administered contrast agent circulates in the subject based on echo data obtained for each time phase from the received signal.
An ultrasonic diagnostic apparatus. The ultrasonic diagnostic apparatus according to claim 2,
For each time phase, the contrast image forming unit selects specific echo data from a plurality of time phase echo data corresponding to the same image position obtained up to that time phase, and the specific echo data is selected. Forming the image data of the contrast image composed of a plurality of pixel data by forming pixel data of the image position from the data;
An ultrasonic diagnostic apparatus. The ultrasonic diagnostic apparatus according to any one of claims 1 to 3,
The reference image forming unit forms image data of a B-mode image that is the reference image based on echo data corresponding to a fundamental wave component included in the received signal,
The contrast image forming unit forms image data of the contrast image based on echo data corresponding to the harmonic component included in the received signal.
An ultrasonic diagnostic apparatus. In the ultrasonic diagnostic apparatus according to any one of claims 1 to 4,
The transmitting / receiving unit forms a frame by scanning an ultrasonic beam, and alternately receives a reception signal for a reference image and a reception signal for a contrast image in units of frames or reception beams.
An ultrasonic diagnostic apparatus. The ultrasonic diagnostic apparatus according to any one of claims 1 to 5,
In the reference image, two or more reference areas are set.
An ultrasonic diagnostic apparatus. The ultrasonic diagnostic apparatus according to any one of claims 1 to 6,
The reference region is set so as to include a characteristic part such as a blood vessel wall or a diaphragm in a reference image.
An ultrasonic diagnostic apparatus.

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