JP2005253642A - Ultrasonic diagnostic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the freedom degree of a design of an ultrasonic diagnostic apparatus which images movement. <P>SOLUTION: A coloring part 42 colors a displacement image outputted from a displacement image forming block 34 at a transmitting/receiving frame rate corresponding to a time phase at that time and outputs it to an adder 44. As for the displacement images at the transmitting/receiving frame rate colored by the coloring part 42, a displacement history image recorded in a history memory 46 is added to the displacement image of the latest frame in the adder 44. The displacement history images, in which the displacement images are composed in time series, are outputted to a frame rate conversion part 28 for every time phase of each transmitting/receiving frame rate and the frame rate conversion part 28 converts the displacement history image from the transmitting/receiving frame rate into a display frame rate. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an ultrasonic diagnostic apparatus, and more particularly to an ultrasonic diagnostic apparatus that images a motion of a target tissue.

  In an ultrasonic diagnostic apparatus, a technique for imaging a motion of a target tissue is known. For example, the ultrasonic diagnostic apparatus described in Patent Document 1 forms a contour image in which a contour of a target tissue is clarified from a two-dimensional ultrasonic image of the target tissue, and stores the contour image in a memory for each frame, A displacement image corresponding to the difference is formed from the past contour image recorded in the memory and the current contour image, and a displacement history image obtained by sequentially synthesizing the displacement images with time is displayed. This ultrasonic diagnostic apparatus is used, for example, for diagnosis of abnormal movement of the myocardium, and can display the movement state of the myocardium between the diastole and the systole of the ventricle over time. It has a tremendous effect in the diagnosis.

  This ultrasonic diagnostic apparatus also has a related improvement technique because of its high practical value. For example, a technique is known in which a displacement history image is clarified by performing a coloring process on a displacement image for each frame formed as described above. By this technique, a plurality of displacement images subjected to coloring processing corresponding to each frame are synthesized, and the resulting displacement history image is displayed like a contour line of a map colored at each height. .

Japanese Patent No. 3045642

  In general, in a conventional ultrasonic diagnostic apparatus that performs a coloring process to clarify a displacement history image, the frame rate for image display matches the frame rate for image data acquisition. That is, the frame rate (transmission / reception frame rate) of the displacement history image formed for each time phase by transmitting / receiving ultrasonic waves and the frame rate (display frame rate) of the displacement history image actually displayed on the screen It was a configuration to match. Usually, the display frame rate is determined depending on the specifications of the display used in the ultrasonic diagnostic apparatus. Therefore, in the case of a configuration in which the transmission / reception frame rate matches the display frame rate, the selection range of the transmission / reception frame rate is narrowed depending on the specifications of the display.

  SUMMARY OF THE INVENTION An object of the present invention is to increase the degree of freedom in device design in an ultrasonic diagnostic apparatus that images motion.

  In order to achieve the above object, an ultrasonic diagnostic apparatus according to a preferred embodiment of the present invention includes a transmission / reception unit that transmits and receives ultrasonic waves into a space including a target tissue to acquire echo data, and the echo data. An ultrasonic image forming unit that forms an ultrasonic image of a target tissue, a contour image forming unit that forms a contour image in which the contour of the target tissue is clarified from the ultrasonic image, and the target tissue from the contour image A motion image forming unit that forms a plurality of motion images in time series reflecting the motion of the image, and a display image that forms a display image by performing a coloring process according to the data acquisition timing on each motion image It has a formation part and a display part which displays the display picture, It is characterized by the above-mentioned.

  In this configuration, the data acquisition timing is the acquisition timing of echo data corresponding to each motion image, and the coloring process according to the data acquisition timing is, for example, a coloring process using colors determined at each data acquisition timing. is there. According to this configuration, it is possible to form a display image at an arbitrary display frame rate by, for example, frame rate conversion processing from each motion image that has been subjected to coloring processing. That is, the display frame rate and the transmission / reception frame rate are not necessarily matched, and the degree of freedom in device design is increased.

  Preferably, the display image forming unit performs the coloring process based on color information indicating a correspondence relationship between the data acquisition timing and a color at the data acquisition timing. Desirably, the display image forming unit extracts a motion image corresponding to a display frame from a plurality of motion images subjected to the coloring process, and forms a display image. Preferably, the motion image forming unit forms, as the motion image, a displacement image representing a difference between the contour image at a predetermined time point and the contour image at a time point earlier than the predetermined time point.

  According to the present invention, for example, it is not necessary to make the display frame rate coincide with the transmission / reception frame rate, so that the degree of freedom in device design can be increased in an ultrasonic diagnostic apparatus that images motion.

  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 block diagram showing the overall configuration thereof. The transmission / reception unit 12 transmits / receives an ultrasonic wave via the probe 10 in a space including the left ventricle as a target tissue. The echo data in the two-dimensional plane including the left ventricle is acquired for each frame of the transmission / reception frame rate and stored in the echo data memory 14. The target tissue is not limited to the heart, but in the following description, the heart will be described as the target tissue. The coordinate conversion unit 26 converts the coordinates of each echo data recorded in the echo data memory 14 from the coordinate system based on the probe to the display coordinate system, and transmits a B-mode image (ultrasonic image) for each frame of the transmission / reception frame rate. ).

  The binarization circuit 30 includes a comparator and the like, binarizes a B-mode image composed of various luminance values output from the coordinate conversion unit 26 based on a predetermined threshold value, and outputs a heart chamber in the left ventricle. A binarized image composed of two luminance values, i.e., a luminance corresponding to the portion and a luminance corresponding to another portion, is formed and output to the displacement image forming block 34.

  The displacement image forming block 34 forms a plurality of time-sequential displacement images related to the heart chamber in the left ventricle based on the binarized image output from the binarization circuit 30, and includes a displacement image memory. 36 and a displacement image extraction unit 38.

  The displacement image memory 36 records the binarized image output from the binarization circuit 30 for each frame of the transmission / reception frame rate. The displacement image extraction unit 38 includes the binarized image of the previous frame recorded in the displacement image memory 36 and the binarized image of the latest temporal frame output from the binarization circuit 30. Comparison is performed to extract a displacement image that is a different portion of the binarized image between time phases. That is, an image of the displaced portion of the heart chamber during one time phase accompanying the left ventricular contraction and expansion motion is extracted. Note that the frame to be compared with the frame of the latest time phase may be a frame of the past time phase, and is not limited to the frame before the one time phase. The displacement image formed for each time phase in the displacement image forming block 34 is output to the display image forming block 40.

  The display image forming block 40 includes a coloring processing unit 42, an adder 44, a history memory 46, a frame rate conversion unit 28, and an image composition unit 48. The coloring processing unit 42 performs coloring processing corresponding to the time phase on the displacement image output from the displacement image forming block 34 for each time phase at the transmission / reception frame rate, and outputs the result to the adder 44. In other words, the displacement image output at the transmission / reception frame rate is subjected to a coloring process using a color corresponding to each frame. Details of the coloring process in the coloring process unit 42 will be described later with reference to FIGS.

  The displacement history image recorded in the history memory 46 is added to the displacement image of the latest frame by the adder 44 in the displacement image for each frame of the transmission / reception frame rate that has been colored by the coloring processing unit 42. Then, it is stored in the history memory 46 as a new displacement history image. The adder 44 performs addition processing for each frame of the transmission / reception frame rate. Thus, the displacement history image in which the displacement images are synthesized with time is output to the frame rate conversion unit 28 for each frame of the transmission / reception frame rate.

  FIG. 2 is a diagram for explaining a displacement history image forming process in the ultrasonic diagnostic apparatus of FIG. Hereinafter, the displacement history image forming process will be described with reference to FIG.

  In FIG. 2, the binarized image (a) output from the binarization circuit 30, the displacement image (b) output from the displacement image extraction unit 38, and the history memory 46 are acquired for the left ventricle. A displacement history image (c) is shown. The binarized image (a), the displacement image (b), and the displacement history image (c) are each formed at a transmission / reception frame rate. The binarized image (a) is classified into two types of luminance values, that is, a luminance value corresponding to the heart chamber 60 and a luminance value corresponding to another part, and as a result, the heart chamber 60 is clarified. is there. The binarized image (a) is formed for each frame of the transmission / reception frame rate. In FIG. 2, binarized images a1 to a4 from frame 1 to frame 4 are shown. From the frame 1 to the frame 4, the heart chamber 60 is gradually reduced, and it is shown that the heart chamber 60 is in the contraction process.

  The displacement image (b) is an image showing a difference portion of the binarized image between time phases, and the displacement image (b) in FIG. 2 is a difference region of the heart chamber between each frame of the binarized image (a). Is shown. That is, the displacement image b1 shows a difference area 62 of the heart chamber 60 between the binarized image a1 and the binarized image a2. This difference area 62 corresponds to the amount of displacement of the heart chamber 60 from frame 1 to frame 2. Similarly, the displacement image b2 shows the difference region of the heart chamber between the binarized image a2 and the binarized image a3, and the displacement image b3 shows the binarized image a3 and the binarized image a4. The difference area of the heart chamber between and is shown.

  The displacement history image (c) is an image in which the displacement image (b) is synthesized over time. That is, the displacement history image c1 in FIG. 2 reflects the displacement image b1 as it is, and the displacement history image c2 is an image in which the displacement image b2 is combined with the displacement image b1. Furthermore, the displacement history image c3 is an image obtained by combining the displacement images b1 to b3.

  When the displacement images are synthesized, the coloring processing unit 42 performs coloring processing on each displacement image. In FIG. 2, the displacement history image (c) is not shown in color for convenience of illustration, but actually, the displacement history image is displayed after the corresponding coloration processing is performed on each of the displacement images b1 to b3. (C) is formed. For this reason, for example, the displacement history image c3 is displayed as a triple ring colored with different colors.

  Returning to FIG. 1, the frame rate conversion unit 28 converts the displacement history image and the B-mode image into a display frame rate. That is, since the displacement history image recorded in the history memory 46 corresponds to the transmission / reception frame rate, the frame rate conversion unit 28 displays the display frame indicated by the display frame rate data input from the control unit (not shown). Get displacement history image at rate. The display frame rate data is set to a display frame rate specified by the user, for example. Further, since the B-mode image output from the coordinate conversion unit 26 is also the transmission / reception frame rate, the frame rate conversion unit 28 converts the B-mode image into the display frame rate.

  The conversion from the transmission / reception frame rate to the display frame rate is performed by selectively extracting frames corresponding to each frame of the display frame rate from a plurality of frames of the displacement history image created at the transmission / reception frame rate. For example, when the displacement history image (c) shown in FIG. 2 is formed at a transmission / reception frame rate of 60 Hz, that is, the displacement history image c1, the displacement history image c2, and the displacement history image c3 are acquired at 1/60 second intervals. In this case, the conversion to the display frame rate of 30 Hz is realized by extracting every other displacement history image acquired at 60 Hz. Specifically, by extracting the displacement history image c1 and the displacement history image c3 as display frames from the displacement history image c1, the displacement history image c2, and the displacement history image c3 acquired at 60 Hz, the 1/30 second interval is obtained. That is, a displacement history image is acquired at 30 Hz. For example, when the display frame rate is 60 Hz, all of the displacement history image c1, the displacement history image c2, and the displacement history image c3 may be extracted without performing the thinning process.

  The frame rate conversion of the B-mode image is the same as that of the displacement history image. That is, a frame corresponding to each frame of the display frame rate is selectively extracted from a plurality of frames of the B-mode image created at the transmission / reception frame rate.

  The transmission / reception frame rate is not limited to 60 Hz. For example, by forming a displacement history image at a higher transmission / reception frame rate, and selectively extracting the displacement history image at a timing according to the display frame rate, the range of selection of the display frame rate is also increased. spread.

  The displacement history image and the B-mode image converted to the display frame rate by the frame rate conversion unit 28 are output to the image composition unit 48. The image composition unit 48 composes the B-mode image and the displacement history image to form a display image, and the display image formed by the image composition unit 48 is displayed on the display 58.

  FIG. 3 is a diagram for explaining the coloring process for the displacement image. Hereinafter, the coloring process for the displacement image will be described with the reference numerals in FIG.

  The displacement image output for each time phase from the displacement image forming block 34 is subjected to a coloring process corresponding to each time phase in the coloring processing unit 42. At this time, a coloration process using colors according to the data acquisition timing of the displacement image is performed on the displacement image for each time phase.

  FIG. 3 shows a graph in which each data acquisition time is associated with the color gradation at that time, with the horizontal axis representing the data acquisition time and the vertical axis representing the color gradation. Here, the data acquisition time is the acquisition time of the echo data, and corresponds to the elapsed time from a certain reference time. For example, the end diastole of the heart is used as the reference time.

  The coloring processing unit 42 performs a coloring process with a color gradation corresponding to the data acquisition time of the displacement image on the displacement image. A displacement image is formed for each time phase of the transmission / reception frame rate and output from the displacement image extraction unit 38. Based on a reference time trigger output from a control unit (not shown), the coloring processing unit 42 sets the input time point of the reference time trigger as time “0” and performs time measurement therefrom, and data corresponding to the horizontal axis of FIG. Measure the acquisition time. When the displacement image is output from the displacement image extraction unit 38 for each time phase, the color gradation is determined from the graph of FIG. 3 using the output time as the data acquisition time, and the coloring process using the determined color gradation is performed. Apply. In this way, the color gradation is determined for each frame with respect to the displacement images output one after another at the transmission / reception frame rate, and the coloring process corresponding to the determined color gradation is executed.

  FIG. 4 is a diagram for explaining the color gradations. For each of the three primary colors “red”, “green”, and “blue”, the horizontal axis represents the data acquisition time and the vertical axis represents the gradation. It is the graph shown as a value. The coloring processing unit 42 determines the gradation of each of the three primary colors corresponding to each data acquisition time from the graph shown in FIG. For example, at the data acquisition time 0, since the “green” and “blue” gradations are 0 and “red” is the maximum gradation 256, the difference area of the displacement image at the data acquisition time 0 (reference numeral 62 in FIG. 2). ) Is colored red. Since the “green” gradation increases from the data acquisition time 0 to 700 ms, the displacement image at the data acquisition time in this range is colored with a mixed color of red and green. As the data acquisition time approaches 700 ms, the green mixing ratio increases. In this way, the color corresponding to each data acquisition time is determined.

数１において、Ｒ，Ｇ，Ｂは、それぞれ「赤」，「緑」，「青」の階調を示している。また、ｎは変位画像のフレーム番号（基準時点をフレームＮｏ．０とした場合の送受信フレームでのフレームＮｏ．）、ｆｒは送受信フレームレート、ｔ_ｅｎｄは色付け処理の終了時間を示している。色付け処理の終了時間は、例えばユーザによって任意に設定され、必要に応じて適宜変更される。数１を利用することにより、変位画像のフレーム番号と送受信フレームレートからそのフレーム番号に対応する三原色それぞれの階調を算出できる。 The gradation of each of the three primary colors can be determined from the following equation.

In Equation 1, R, G, and B indicate gradations of “red”, “green”, and “blue”, respectively. Further, n represents a frame number of the displacement image (a frame number in a transmission / reception frame when the reference time point is frame No. 0), fr represents a transmission / reception frame rate, and t _end represents an end time of the coloring process. The end time of the coloring process is arbitrarily set by the user, for example, and is appropriately changed as necessary. By using Equation 1, the gradation of each of the three primary colors corresponding to the frame number can be calculated from the frame number of the displacement image and the transmission / reception frame rate.

  As described above, in the present embodiment, each displacement image is subjected to a coloring process according to the data acquisition timing to form a displacement history image, and then converted to a frame rate to display a displacement history image at a display frame rate. Is acquired. Therefore, the color of each frame of the displayed displacement history image does not depend on the display frame rate, and is determined at the data acquisition timing, and is acquired at the same time between two images having different display frame rates. The displacement history image can be displayed in the same color.

  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.

  For example, a recording device such as a hard disk (not shown) that records displacement history images successively recorded at the transmission / reception frame rate in the history memory 46 of FIG. 1 and B-mode images successively formed at the transmission / reception frame rate in the coordinate conversion unit 26. The frame rate conversion unit 28 reads out each frame image of the displacement history image and the B-mode image one after another from the hard disk at a predetermined timing, thereby realizing reproduction at an arbitrary speed (for example, slow reproduction). May be. Since the color applied to the displacement history image is determined according to the data acquisition timing, even in the case of slow playback, the color of each frame of the displacement history image for display is a color according to the data acquisition timing. .

1 is a block diagram showing an overall configuration of an ultrasonic diagnostic apparatus according to the present invention. It is a figure for demonstrating the formation process of a displacement log | history image. It is a figure for demonstrating the coloring process with respect to a displacement image. It is a figure for demonstrating a color gradation.

Explanation of symbols

  28 frame rate conversion unit, 38 displacement image extraction unit, 42 coloring processing unit, 46 history memory, 48 image composition unit.

Claims (4)

A transmission / reception unit for acquiring echo data by transmitting / receiving ultrasonic waves in a space including the target tissue;
An ultrasound image forming unit that forms an ultrasound image of the target tissue from the echo data;
From the ultrasonic image, a contour image forming unit that forms a contour image that clarifies the contour of the target tissue;
A motion image forming unit that forms a plurality of motion images in time series reflecting the motion of the target tissue from the contour image;
A display image forming unit that forms a display image by performing a coloring process according to the data acquisition timing for each motion image;
A display unit for displaying the display image;
An ultrasonic diagnostic apparatus comprising: The ultrasonic diagnostic apparatus according to claim 1,
The display image forming unit performs the coloring process based on color information indicating a correspondence relationship between the data acquisition timing and a color at the data acquisition timing.
An ultrasonic diagnostic apparatus. The ultrasonic diagnostic apparatus according to claim 1 or 2,
The display image forming unit extracts a motion image corresponding to a display frame from a plurality of motion images subjected to the coloring process to form a display image.
An ultrasonic diagnostic apparatus. The ultrasonic diagnostic apparatus according to any one of claims 1 to 3,
The motion image forming unit forms, as the motion image, a displacement image representing a difference between the contour image at a predetermined time and the contour image at a time earlier than the predetermined time.
An ultrasonic diagnostic apparatus.

Images