JP3889121B2 - Ultrasonic diagnostic equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ultrasonic diagnostic apparatus that obtains and displays an ultrasonic image of a diagnostic region in a subject using ultrasonic waves, and particularly performs an averaging process on an image of an object that moves on a moving image. The present invention relates to an ultrasonic diagnostic apparatus capable of reducing noise such as speckle noise without causing deterioration of image quality and luminance reduction that are displayed in a multiple manner.
[0002]
[Prior art]
In general, an ultrasonic image obtained by an ultrasonic diagnostic apparatus is mixed with noise having irregular periods called speckle noise. The speckle noise is considered to be that small bright spot groups appear at random due to interference of scattered waves generated in various phases by a reflection point group of biological tissue that is sufficiently smaller than the wavelength of ultrasonic waves. This speckle noise is known to appear superimposed on the original reflected echo signal over the entire area of the B-mode image. For example, in an ultrasound image of the heart, speckle noise overlaps the reflected echo signal of structures such as the heart wall, disturbing the original signal, causing image quality degradation such as image flickering, and reflectors such as the heart cavity Speckle noise also appeared in the part where there was no, and the image quality deteriorated.
[0003]
In general, speckle noise is considered to change its shape greatly depending on the arrangement of minute scatterers distributed in the living body, and it is known that the speckle noise pattern changes as the living tissue moves. However, how the pattern changes, direction, brightness, etc., is not uniform. From this, it is known that speckle noise changes irregularly when the living body is moving.
[0004]
On the other hand, in the conventional ultrasonic diagnostic apparatus, the addition averaging process weighted with time by the frame correlation process is performed to reduce the speckle noise of the moving image. This frame correlation processing is a method called “frame correlation” for checking whether there is any correlation between the current and past plural frames of images, or taking the average of the luminance of the present and past plural frames of images at the same point. Speckle noise is reduced by a technique called “SCC (scan correlation) scan correlation”.
[0005]
[Problems to be solved by the invention]
However, in the frame correlation processing in such a conventional ultrasonic diagnostic apparatus, the influence of the past images of a plurality of frames remains. For example, a heart valve that moves at high speed should be originally one, but the “tailing” phenomenon that multiple images are displayed in series and the boundary between the heart wall and the heart chamber blurs. Phenomenon occurred and image quality could be degraded. In addition, a high-intensity tissue suddenly appearing in a low-luminance part of the display image may be displayed with a lower luminance than the original by performing the above-described averaging process.
[0006]
Therefore, the present invention addresses such problems and does not cause deterioration in image quality or brightness reduction that is displayed in multiple due to addition averaging processing of images of moving objects on moving images. An object is to provide an ultrasonic diagnostic apparatus capable of reducing noise such as speckle noise.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, an ultrasonic diagnostic apparatus according to the present invention includes a probe that transmits and receives ultrasonic waves in a subject, a reflected echo signal that is generated and received by driving the probe. An ultrasonic transmission / reception unit for processing, a storage unit for recording a plurality of frames of ultrasonic image data obtained by digitizing the processed reflected echo signal, and a plurality of recorded image data of continuous frames The pattern generation means for generating a dynamic pattern indicating the characteristics of the moving image from the image data sequence at the same address of each frame, and image processing on the ultrasonic image data according to the generated dynamic pattern an output data processing unit, the ultrasonic diagnostic apparatus comprising an image display unit which displays the input image data the image processing, the pattern generation The stage obtains an image data sequence at the same address of a plurality of consecutive frames of image data read from the storage unit, and each of these image data sequences has a luminance value of 2 in comparison with a predetermined threshold value. A dynamic pattern is generated by digitizing and arranging the binarized luminance data in the order of obtaining each data .
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a block diagram showing an embodiment of an ultrasonic diagnostic apparatus according to the present invention. This ultrasonic diagnostic apparatus obtains and displays an ultrasonic image of a diagnostic region in a subject using ultrasonic waves. As shown in FIG. 1, a probe 1, an ultrasonic transmission / reception unit 2, , A storage unit 3, a binarization circuit / pattern generation unit 4, a pattern-specific output data calculation / selection circuit 5, and an image display unit 6.
[0010]
The probe 1 transmits and receives ultrasonic waves into the subject. Although not shown, an ultrasonic transducer that actually emits ultrasonic waves and receives reflected echoes from the subject is included in the probe 1. Is provided. The ultrasonic transmission / reception unit 2 drives the probe 1 to generate ultrasonic waves and processes the received reflected echo signal. Although not shown in the drawing, the ultrasonic transmission / reception unit 2 includes an ultrasonic wave in the probe 1. A transmission pulse generator for supplying a transmission pulse of ultrasonic launch to the ultrasonic transducer, a reception amplifier for amplifying a reflected echo signal received by the ultrasonic transducer, and controlling the transmission pulse generator and the reception amplifier A control circuit is provided. The storage unit 3 records a plurality of frames of ultrasonic image data obtained by digitizing the reflected echo signal from the ultrasonic transmission / reception unit 2 in time series, and includes a plurality of frame memories 3a, 3a, 3b, ..., 3e are provided.
[0011]
The binarization circuit / pattern generation unit 4 reads the image data of a plurality of continuous frames F ₁ , F ₂ ,..., F ₅ from the storage unit 3 in parallel, and the image data at the same address of each frame F _{1 to} F _5. This is a pattern generation unit that generates a dynamic pattern indicating the characteristics of a moving image from a sequence, and generates a dynamic pattern based on the latest plural frames of an ultrasonic image to be displayed. The pattern-specific output data calculation / selection circuit 5 serves as output data processing means for performing image processing on the ultrasonic image data in accordance with the dynamic pattern generated by the binarization circuit / pattern generation unit 4. It is. Further, the image display unit 6 receives and displays the image data from the pattern-specific output data calculation / selection circuit 5, and is composed of, for example, a television monitor.
[0012]
Here, in the present invention, the binarization circuit / pattern generation unit 4 obtains an image data sequence at the same address of the image data of a plurality of consecutive frames F _{1 to} F ₅ read from the storage unit 3 , Each of these image data strings is binarized by the magnitude of the luminance value compared with a predetermined threshold value, and the dynamic data pattern is generated by arranging the binarized luminance data in the order in which each data is obtained. It has become.
Next, the operation of the thus configured ultrasonic diagnostic apparatus will be described with reference to FIGS. First, in FIG. 1, a probe 1 scans an ultrasonic beam into a subject for constructing a two-dimensional image, and a reflected echo from the subject is received by an ultrasonic transmission / reception unit 2. The received signals are digitized and then sequentially stored in the frame memories 3a to 3e of the storage unit 3 capable of recording a plurality of frames of ultrasonic images continuously over time.
[0013]
Next, the binarization circuit / pattern generation unit 4 simultaneously reads in parallel n frames of image data from the storage unit 3 in parallel (step A in FIG. 2), and images at the same point (same address) in each frame. A data string is acquired (step B in FIG. 2). That is, as shown in FIG. 3, for example, image data of 5 frames F _{1 to} F ₅ recorded respectively in 5 frame memories 3a to 3e are read in parallel, and the same point on each frame F _{1 to} F ₅ is read. Image data P ₁ , P ₂ ,..., P ₅ are acquired. At this time, the frames F _{1 to} F ₅ are arranged in time series, the first frame F ₁ is the oldest, the second frame F ₂ is the oldest, and the fifth frame F ₅ is the latest frame. It has become.
[0014]
Next, in order to detect the characteristic of the moving image at the same point represented by the image data string P ₁ to P ₅ of the above to generate a dynamic pattern by patterning the image data string P ₁ to P _5. That is, each data of the image data strings P _{1 to} P ₅ is binarized and arranged in the order in which the data is obtained and patterned (step C in FIG. 2). As a patterning method, first, each data of the image data strings P _{1 to} P ₅ is binarized as shown in FIG. At this time, the threshold value for binarization distinguishes the luminance level B ₁ of the tissue such as the heart valve and the heart wall from the luminance level B ₂ other than the tissue such as the heart cavity, for example, in the case of a heart image. Set the brightness value so that Then, the binarized luminance data is arranged and patterned in the order in which the data P _{1 to} P ₅ are obtained, that is, the order of the frames F _{1 to} F ₅ .
[0015]
FIG. 5 shows a state in which a dynamic pattern is generated from the image data sequences P _{1 to} P _{5 of the} continuous frames F _{1 to} F ₅ . In this FIG. 5, the case where the biological tissue is moving from left to right on each of the fan-shaped frames F _{1 to} F ₅ is shown as an example. In this example, not been moved biological tissue is still for the same interest points P ₁ to P ₄ in the frame F ₁ to F _4, the image data of the noted points P ₁ to P ₄ in the low luminance are displayed, in the latest frame F ₅ has been living tissue is moved to the same interest points P _5, the image data of the noted point P ₅ is displayed at high luminance. Therefore, by the binarization processing shown in FIG. 4, the binarization result is that the values of the attention points P _{1 to} P ₄ are “0” and the value of the attention point P ₅ is “1” as shown in FIG. " Then, these binarized values are arranged in the order of the frames F _{1 to} F ₅ to generate a dynamic pattern.
[0016]
Next, the pattern-specific output data calculation / selection circuit 5 detects the feature of the moving image from the shape of the dynamic pattern obtained as described above (step D in FIG. 2). Now, some examples of the shape of the dynamic pattern obtained as described above are shown in FIGS. FIG. 6 shows an example of the shape of a dynamic pattern focusing on a certain point on the image when, for example, the heart is displayed. As shown in FIG. 6A, the dynamic pattern obtained at this point has a shape in which the point of interest displayed at a high luminance is moving in a certain direction as time passes. In this case, it can be predicted that the heart valve (high luminance display) has passed in the heart chamber (low luminance display) in the past. Next, as shown in FIG. 6B, in the case where many attention points displayed with high brightness move in a certain direction with the passage of time, the heart wall (high brightness display) has been detected in the past. It can be expected that the part has moved into the heart chamber (low luminance display) due to the expansion of the heart. Further, as shown in FIG. 6C, in the case where the attention point displayed with high luminance appears at one end of many attention points displayed with low luminance, the intracardiac (low luminance display) ), A heart valve or heart wall (high luminance display) can be expected. In the case of the dynamic patterns shown in FIGS. 6A to 6C, it can be said that the feature of the moving object on the moving image is detected.
[0017]
Next, as shown in FIG. 6D, when the values obtained by binarizing the luminance values of the image data sequences P _{1 to} P ₅ are all the same in the high luminance state or the low luminance state, The point can be expected to be stationary. Further, as shown in FIG. 6E, in the case where the values obtained by binarizing the luminance values of the image data sequences P _{1 to} P ₅ are randomly changing between high luminance and low luminance, these are noises. Can be expected. With the pattern thus obtained, it is possible to predict what is displayed at the point.
[0018]
Next, the pattern-specific output data calculation / selection circuit 5 performs image processing on the points P _{1 to} P ₅ on the image in accordance with the characteristics of the moving image (dynamic pattern shape) (step E in FIG. 2). ). That is, in the case of the dynamic patterns shown in FIGS. 6A to 6C, the moving object is displayed on the moving image. In this case, the image is displayed as it is. Process. In addition, the dynamic pattern shown in FIG. 6D is characterized in that the point on the moving image is in a stationary state. In this case, image processing is performed so that the image is smoothed and displayed. Furthermore, the dynamic pattern shown in FIG. 6E is characterized in that the point on the moving image is noise. Only in this case, image processing for noise removal is performed.
[0019]
As the image processing according to the dynamic pattern, the weighted average of the image data sequences P _{1 to} P ₅ whose weighting coefficients are changed according to the pattern, the latest image data P _5, fixed luminance, or the like may be output as the image processing result. Then, after image processing for the attention points P _{1 to} P ₅ is performed on the entire image, the image data after image processing is sent to the image display unit 6 to display an ultrasonic image.
[0021]
【The invention's effect】
Since the present invention is configured as described above, a plurality of continuous images read from a storage unit that records a plurality of frames of time-series ultrasonic image data obtained by digitizing the reflected echo signals processed by the ultrasonic transmission / reception unit. An image data sequence at the same address of the image data of the frame is acquired, and each of these image data sequences is binarized by the magnitude of the luminance value compared with a predetermined threshold value. The feature that the moving object is displayed on the moving image according to the feature of the moving image (the shape of the dynamic pattern) is provided by providing the pattern generating means that generates the dynamic pattern by arranging in the order that the data was obtained. If the feature is that the point on the moving image is still, the image is smoothed and displayed. For feature that the point is the noise can be displayed by removing the noise. As a result, the “tailing” phenomenon and the “blurring” phenomenon that occurred in the frame correlation processing in the conventional ultrasonic diagnostic apparatus are removed, and the image of the moving object on the moving image is added and averaged. Thus, noise such as speckle noise can be reduced without causing deterioration of image quality and luminance reduction displayed in multiple.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an embodiment of an ultrasonic diagnostic apparatus according to the present invention.
FIG. 2 is a flowchart showing an image processing operation of a binarization circuit / pattern generation unit and a pattern-specific output data calculation / selection circuit of the ultrasonic diagnostic apparatus.
FIG. 3 is an explanatory diagram illustrating a state in which image data of consecutive frames of n frames are simultaneously read in parallel from a storage unit by a binarization circuit / pattern generation unit, and an image data sequence of the same point (same address) of each frame is acquired. It is.
FIG. 4 is an explanatory diagram showing a state in which each data of the image data sequence obtained as described above is binarized.
FIG. 5 is an explanatory diagram showing a state in which a dynamic pattern is generated from the continuous image data sequence of a plurality of frames.
FIG. 6 is an explanatory diagram showing an example of the shape of a dynamic pattern focused on a certain point on an image when a heart is displayed, for example.
[Explanation of symbols]
1 ... probe 2 ... ultrasonic transmitting and receiving unit 3 ... storage unit 3 a to 3 e ... frame memory 4 ... binarization circuit pattern generating unit 5 ... each pattern output data arithmetic and selection circuit 6 ... image display unit F ₁ to F ₅ ... Frame

Claims (1)

A probe that transmits and receives ultrasonic waves in the subject, an ultrasonic transmission and reception unit that drives the probe to generate ultrasonic waves and processes the received reflected echo signals, and the processed reflected echo signals A storage unit for recording a plurality of frames of ultrasonic image data obtained by digitization in time series, and reading the recorded consecutive frames of image data in parallel from an image data sequence at the same address of each frame. a pattern generating means for generating a dynamic pattern indicating a characteristic, and an output data processing means for performing image processing for the data of the ultrasonic image in accordance with a dynamic pattern that is the product, and inputs image data the image processing In an ultrasonic diagnostic apparatus comprising an image display unit for displaying ,
The pattern generation means obtains an image data sequence at the same address of a plurality of consecutive frames of image data read from the storage unit, and compares each of the image data sequences with a predetermined threshold value to obtain a luminance value. An ultrasonic diagnostic apparatus characterized in that it binarizes in size and generates a dynamic pattern by arranging the binarized luminance data in the order in which each data was obtained .

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