JPH11151242A - Sampling data processing method, device therefor and ultrasonic imaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To always obtain a correct blood stream image, etc., by judging abnormality based on a predictive value, which is obtained by sampling plural data and predicting the value of each of plural data, to correct a value judged to be abnormal. SOLUTION: A doppler processing part inputting an echo received signal from a transmission and reception part with a preprocessing circuit 122 provided with a sampling circuit 150, a buffer memory 152 and a sample value correcting processor 154. Then, the circuit 150 samples an inputted signal by a prescribed sampling rate to obtain a digital data string and the memory 152 temporarily store the packet of plural sampled data. Next, a sample value correcting processor 154 predicts the value of sampling data and when actually obtained sampling data is different from the predicted value over a prescribed allowable range, judges it to be an abnormal value and corrects this abnormal value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for processing sampling data and an ultrasonic imaging apparatus, and more particularly, to a method and apparatus for processing abnormal data contained in sampling data, and The present invention relates to an ultrasonic imaging apparatus provided with such a sampling data processing device.

[0002]

2. Description of the Related Art For example, in an ultrasonic
The (echo) signal is Doppler processed to obtain a blood flow image and the like. In this case, the Doppler process is performed on a data sequence obtained by converting the echo signal into digital data, that is, on sampling data.

[0003]

SUMMARY OF THE INVENTION For example, noise
If abnormal data is mixed in the sampling data due to the influence of the above, the Doppler processing is hindered, and a correct blood flow image or the like cannot be obtained. To prevent this, abnormal data may be identified and corrected, but it has been difficult to reliably identify which data in the data string is abnormal.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a sampling data processing method and apparatus for identifying and correcting abnormal data, and to provide such a sampling data processing apparatus. It is an object of the present invention to realize an ultrasonic imaging apparatus provided with the apparatus.

[0005]

Means for Solving the Problems (1) According to a first aspect of the present invention, a plurality of data are sampled, and a prediction value obtained by predicting a value of each of the plurality of data is calculated. And the value determined to be abnormal is corrected.

(2) A second invention for solving the above problem is obtained by sampling means for sampling a plurality of data and estimating a value of each of the plurality of data obtained by the sampling means. It is characterized by comprising a determining means for determining based on a predicted value, and a correcting means for correcting a value determined as abnormal by the determining means.

(3) According to a third aspect of the present invention, there is provided a transmitting / receiving means for transmitting an ultrasonic wave to a subject to receive an echo, a sampling means for sampling an echo signal received by the transmitting / receiving means, Determining means for determining based on a predicted value obtained by predicting a value of each of the plurality of data obtained by the sampling means, correcting means for correcting a value determined as abnormal by the determining means, And Doppler processing means for performing Doppler processing using a plurality of corrected data.

In the first to third aspects of the present invention, it is preferable to perform forward prediction based on the prediction in order to improve real-time performance of data processing. In the first to third aspects of the present invention, it is preferable to perform both forward prediction and backward prediction based on the above-described prediction, in that the determination has a wide range.

Further, in the third invention, it is preferable that a rejection means for rejecting the plurality of data when an abnormal portion in the plurality of data exceeds a limit is provided in order to perform high quality Doppler processing.

(Operation) In the present invention, abnormal data is identified and corrected by comparing predicted data with actually sampled data.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiment.

FIG. 1 shows a block (bloc) of an ultrasonic imaging apparatus.
k) Show the figure. This apparatus is an example of an embodiment of the ultrasonic imaging apparatus of the present invention. The configuration of the present apparatus shows an example of an embodiment relating to the apparatus of the present invention. An example of an embodiment of the method of the present invention is shown by the operation of the present apparatus.

(Configuration) The configuration of the present apparatus will be described. As shown in FIG. 1, the present apparatus has an ultrasonic probe (probe) 2. The ultrasonic probe 2 has an ultrasonic transducer array (not shown). The ultrasonic transducer array is formed, for example, along an arc that protrudes forward. That is, the ultrasonic probe 2 is a convex probe (convex probe).
probe). The ultrasonic probe 2 is used in contact with the subject 4 by an operator (not shown).

The ultrasonic probe 2 is connected to a transmitting / receiving unit 6. The transmission / reception unit 6 transmits a driving signal to the ultrasonic probe 2 to transmit ultrasonic waves into the subject 4. The transmitting and receiving unit 6 also receives an echo signal from the subject 4 that the ultrasonic probe 2 has received.

FIG. 2 shows a block diagram of the transmitting / receiving section 6. As shown in FIG. In the figure, a transmission timing (timing) generating circuit 602
Is configured to periodically generate a transmission timing signal and input the transmission timing signal to a transmission beamformer (beamformer) 604.

The transmission beamformer 604 performs transmission beamforming (beam fo) based on the transmission timing signal.
rming) signal, that is, a plurality of drive signals for driving a plurality of ultrasonic transducers (transducers) in the ultrasonic transducer array with a time difference, and a transmission / reception switching circuit 606.
Is entered.

The transmission / reception switching circuit 606 inputs a plurality of drive signals to a selector 608. The selector 608 selects a plurality of ultrasonic transducers constituting a transmission aperture from an array of ultrasonic transducers, and applies a plurality of drive signals to them.

The plurality of ultrasonic transducers respectively generate a plurality of ultrasonic waves having a phase difference corresponding to a time difference between a plurality of drive signals. An ultrasonic beam is formed by wavefront synthesis of those ultrasonic waves. The transmission direction of the ultrasonic beam is determined by the transmission aperture selected by the selector 608.

The transmission of the ultrasonic beam is repeated at regular time intervals by a transmission timing signal generated by a transmission timing generation circuit 602. The transmission direction of the ultrasonic beam is sequentially changed by switching the transmission aperture by the selector 608. Thereby, the inside of the subject 4 is scanned by the sound ray formed by the ultrasonic beam. That is, the inside of the subject 4 is scanned in a sound ray sequence.

The selector 608 selects a plurality of ultrasonic transducers constituting a receiving aperture from an array of ultrasonic transducers, and inputs a plurality of echo signals received by the ultrasonic transducers to a transmission / reception switching circuit 606. It is supposed to.

The transmission / reception switching circuit 606 inputs a plurality of echo signals to the reception beamformer 610. The receiving beamformer 610 adds a time difference to the plurality of echo reception signals to adjust phases, and then adds them to form beam reception reception, that is, an echo reception signal on a reception sound ray. I have. The selector 608 also scans the received sound ray in accordance with the transmitted wave.

The scanning as shown in FIG. 3, for example, is performed by the ultrasonic probe 2 and the transmitting / receiving unit 6. That is, as shown in FIG.
02 moves on the circular arc 204, so that the fan-shaped 2
The dimension area 206 is scanned in the θ direction, and so-called convex scanning is performed. When the sound ray 202 is extended in the direction opposite to the ultrasonic wave transmission direction (z direction), all the sound rays intersect at one point 208. Point 208 is a divergence point of all sound rays.

The transmitting / receiving section 6 is connected to the B-mode processing section 10 and the Doppler processing section 12. The echo reception signal for each sound ray output from the transmission / reception unit 6 is transmitted to the B-mode processing unit 1
0 and are input to the Doppler processing unit 12. The portion including the ultrasonic probe 2 and the transmitting / receiving section 6 is an example of the embodiment of the transmitting / receiving means in the present invention.

The B-mode processing section 10 forms B-mode image data. The B-mode processing unit 10 includes a logarithmic amplifier circuit 102 and an envelope detection circuit 104 as shown in FIG.
It has. The B-mode processing unit 10 includes a logarithmic amplifier 1
02, the echo reception signal is logarithmically amplified, and the envelope detection circuit 1
At 04, a signal representing the intensity of the echo at each reflection point on the sound ray by performing envelope detection, that is, an A-scope signal is obtained. Mode image data is formed.

The Doppler processing section 12 forms Doppler image data. As shown in FIG. 5, the Doppler processing unit 12 includes a quadrature detection circuit 120, a preprocessing circuit 122,
TI filter (moving target indication filter) 12
4. Autocorrelation circuit 126, average flow velocity calculation circuit 128, dispersion calculation circuit 130, and power calculation circuit 132
It has.

In the Doppler processing unit 12, the quadrature detection circuit 1
At step 20, the echo reception signal is subjected to quadrature detection to obtain two signals having a phase difference of 90 ° from each other, that is, an in-phase signal i and a quadrature signal q. The preprocessing is performed by the processing circuit 122, and MT
The I filter 124 performs MTI processing to extract a Doppler signal.

The autocorrelation circuit 126 generates the MTI
An autocorrelation operation is performed based on the output signal of the filter 124, an average flow velocity is obtained from the result of the autocorrelation operation in the average flow velocity operation circuit 128, and a variance of the flow velocity is obtained from the autocorrelation operation result in the dispersion operation circuit 130. The power of the Doppler signal is obtained from the autocorrelation calculation result. MTI filter 124 to power operation circuit 13
2 is an example of the embodiment of the Doppler processing means in the present invention.

By the Doppler processing unit 12 described above, each data (average flow velocity and its variance of the blood flow in the subject 4 and other Doppler signal sources (hereinafter referred to as blood flow and the like) and the data representing the power of the Doppler signal). Doppler image data) is obtained for each sound ray. The flow velocity is obtained as a component in the sound ray direction. In addition, the direction of the flow is distinguished from the approaching direction and the away direction.

The B-mode processing unit 10 and the Doppler processing unit 12 are connected to an image processing unit 14. Image processing unit 1
Reference numeral 4 is for generating an image based on data input from the B-mode processing unit 10 and the Doppler processing unit 12, respectively.

As shown in FIG. 6, the image processing unit 14 includes a sound ray data memory (d) connected by a bus 140.
ata memory) 142, digital scan converter
(digital scan converter) 144, an image memory 146, and an image processor 148.

The B-mode image data and the Doppler image data input for each sound ray from the B-mode processing unit 10 and the Doppler processing unit 12 are stored in the sound ray data memory 142, respectively. Thereby, the sound ray data memory 14
2, a sound ray data space is formed.

Digital Scan Converter 144
Is for converting data in a sound ray data space into data in a physical space by scan conversion. The image data converted by the digital scan converter 144 is stored in the image memory 146. That is, the image memory 1
Reference numeral 46 stores image data of the physical space. The image processor 148 performs predetermined data processing on the data in the sound ray data memory 142 and the image memory 146, respectively. The details of the data processing will be described later.

The display unit 16 is connected to the image processing unit 14. The display unit 16 is provided with an image signal from the image processing unit 14 and displays an image based on the image signal. The display unit 16 can display a color image.

The transmission / reception section 6, B-mode processing section 10,
Doppler processing unit 12, image processing unit 14, and display unit 16
Is connected to the control unit 18. The control unit 18 supplies a control signal to each unit to control its operation. Also, various notification signals are input from each of the controlled units. Under the control of the control unit 18, the B mode operation and the Doppler mode operation are executed.

An operation unit 20 is connected to the control unit 18. The operation unit 20 is operated by the operator, and the control unit 18
The user inputs desired commands and information. The operation unit 20 includes, for example, an operation panel provided with a keyboard and other operation tools.

FIG. 7 shows a block diagram of the preprocessing circuit 122 for the system of the in-phase signal i. Although not shown, the same applies to the system of the quadrature signal q. As shown in the figure, the preprocessing circuit 122 includes a sampling circuit 1
50, a buffer memory 152 and a sample value modification processor 154. The preprocessing circuit 122 is an example of an embodiment of the sampling data processing device according to the present invention.

The sampling circuit 150 is an example of the embodiment of the sampling means in the present invention. The sampling circuit 150 is configured to sang the input signal at a predetermined sampling rate to obtain a digital data sequence. The buffer memory 152 is configured to temporarily store a plurality of packets of data that have been sanguled. 1
The packet includes, for example, data for one sound ray.

The sample value correction processor 154 is an example of the embodiment of the judgment means in the present invention. Also,
It is an example of embodiment of the correction means in this invention. The sample value correction processor 154 includes, for example, a digital
Signal processor (DSP: digital signal processor)
And so on. Sample value correction processor 15
Numeral 4 checks the value of the sampling data stored in the buffer memory 152 and corrects an abnormal value.

To find outliers, sample value correction processor 154 is adapted to predict the value of the sampled data. The prediction of the value of sampling data is
For example, this is performed using a prediction filter (filter) or the like. The prediction filter is a known linear prediction algorithm (algorithm) as described in, for example, a linear prediction of speech issued by Corona Co., Ltd. on March 25, 1980, translated by Kuki Suzuki, pp. 40-49.
Etc. This prediction filter can be said to be a kind of extrapolation filter.

By the prediction filter, the sample value correction processor 154, as shown in FIG. 8, for example, stores a series of m sample data x (n-1) to x (n) on the time axis t stored in the buffer memory 152. −m), the forward prediction, that is, the prediction of the data after the data x (n) (future) is performed, or the backward prediction, that is,
The data before (past) data x (nm-1) is predicted.

If the actually obtained sampling data matches the predicted value within a predetermined allowable range, it is determined to be a normal value. If the sampling data exceeds the predetermined allowable range and differs from the predicted value, it is determined to be an abnormal value. judge. For the data determined to be an abnormal value, interpolation data is further obtained by interpolation (extrapolation interpolation) from normal data in the vicinity of the data, and replaced with this interpolation data. Alternatively, replacement is performed with the predicted value of the prediction filter.

The sample value correction processor 154
In the case where there is data that has a value significantly different from the sampling data sequence in the buffer memory 152, before applying the prediction filter, the data is replaced with interpolation data obtained from neighboring data in advance. deep. This is preferable in that the prediction by the prediction filter is optimized.

In the forward prediction, the data x (n) whose value has been determined as described above is added to the head of the data string, and the data x (n-n-
Excluding m), the data of the m samples of the new combination is applied to the prediction filter, a predicted value at the position of the next data x (n + 1) is obtained, and this is compared with the actual sampled data x (n + 1). And check for any abnormalities. Then, the data determined to be abnormal is replaced with substitute data such as interpolation data.

In the same manner as described above, the prediction filter is applied while sequentially changing the combination of sampling data, and the detection and correction of abnormal values proceeds in the right direction (future) in FIG. When the accuracy of the prediction filter is high, a predetermined number of data may be replaced instead of one by one. This is preferable in that the efficiency of the filtering process is improved.

For updating the backward prediction, the same processing as described above is performed in the leftward direction (past) in FIG. At this time, if the past data has already been determined by the forward prediction as described above, a double check can be performed by the backward prediction.

When a double check is performed, an abnormality is determined if it is determined to be abnormal in either the forward direction or the backward direction, so that an abnormality can be determined on the safe side.
In addition, it is possible to prevent the determination from becoming excessively severe by determining that the abnormality is abnormal only in both cases. That is, by performing a double check,
It is possible to perform a wider range of data determination than when only one of the forward prediction and the backward prediction is performed.

It is preferable to use only one of the forward prediction and the backward prediction in terms of saving processing time. In this case, it is preferable to adopt forward prediction in order to improve real time performance.

When the prediction filter is not used, abnormal values are detected and corrected as follows. That is, with respect to each of the m sample data, interpolation data based on the remaining data excluding the data is obtained, and if the difference from the interpolation data deviates from a predetermined allowable range, it is regarded as abnormal,
Replace with interpolation data.

With the sample value correction function as described above,
The data in the buffer memory 152 is corrected for abnormal values,
A consistent data sequence results. The sample value modification processor 154 also determines the location (bin)
n)), the number, the packet number and the like are notified to the control unit 18.

The control unit 18 determines the
Packets whose correction points exceed a predetermined limit are rejected (rejected). The control unit 18 is an example of an embodiment of a rejection unit in the present invention. Since the data of the packet having many correction points has low reliability, the use of such data may deteriorate the quality of the Doppler image. Therefore, by rejecting such data, it is possible to prevent the image quality from being lowered.

(Operation) The operation of the present apparatus will be described. The operator touches the ultrasonic probe 2 at a desired position on the subject 4,
By operating the operation unit 20, for example, imaging using both the B mode and the Doppler mode is performed. The imaging is performed by a time sharing operation of the B mode and the Doppler mode under the control of the control unit 18. That is, for example, a mixed scan of the B mode and the Doppler mode is performed at a rate of performing the B mode scan once every several times the Doppler mode scan is performed.

In the B mode, the transmission / reception unit 6 scans the inside of the subject 4 in the order of sound rays through the ultrasonic probe 2 and receives the echoes one by one. B-mode processing unit 10
Is a logarithmic amplification of the echo reception signal input from the transmission / reception unit 6 by the logarithmic amplification circuit 102 and an envelope detection by the envelope detection circuit 104 to obtain an A scope signal. Form.

The image processing unit 14 stores the B-mode image data for each sound ray input from the B-mode processing unit 10 in the sound ray data memory 142. Thus, a sound ray data space for the B-mode image data is formed in the sound ray data memory 142.

In the Doppler mode, the transmitting / receiving section 6
Scans the inside of the subject 4 in the order of sound rays while receiving and transmitting a plurality of times per sound ray through the ultrasonic probe 2, and receives the echoes one by one.

In the Doppler processing unit 12, the quadrature detection circuit 1
20 quadrature-detects the echo reception signal to separate it into an in-phase signal i and a quadrature signal q. The pre-processing circuit 122 performs the above-described pre-processing on the in-phase signal i and the quadrature signal q to prepare a data string containing no abnormal values.

The MTI filter 124 performs an MTI process on such a data string. The MTI process is performed using a plurality of echo reception signals per sound ray, that is, a plurality of data packets. Each data packet does not include abnormal data due to pre-processing.
The TI filter 124 can perform the MTI processing without failure, and can extract a correct Doppler signal.

The autocorrelation circuit 126 includes the MTI filter 12
An autocorrelation operation is performed based on the data input from step 4. Based on the data input from the autocorrelation circuit 126, the average flow velocity calculation circuit 128 calculates the average flow velocity, the variance calculation circuit 130 calculates the variance of the flow velocity, and the power calculation circuit 132 calculates the power. These calculated values become Doppler image data representing, for example, the average flow velocity of the blood flow and the like, the variance thereof, and the power of the Doppler signal for each sound ray. Since the MTI filter 124 has correctly extracted the Doppler signal, Doppler image data can be normally obtained.

The image processing section 14 stores Doppler image data for each sound ray input from the Doppler processing section 12 in the sound ray data memory 142. As a result, a sound ray data space for Doppler image data is formed in the sound ray data memory 142.

The image processor 148 scan-converts the Doppler image data in the sound ray data memory 142 by the digital scan converter 144 and
Write to 6. At this time, the Doppler image data is written as image data for a color flow mapping (CFM) image and image data for a power Doppler image in which variance is added to the flow velocity.

The image processor 148 writes the B-mode image, the CFM image, and the power Doppler image in separate areas. The B-mode image is an image showing a tomographic image of the body tissue on the scanning plane. The CFM image is an image showing a two-dimensional distribution of the velocity of the blood flow or the like on the scanning plane. The power Doppler image is an image indicating the location of a blood flow or the like on the scanning plane.

The operator operates the operation unit 20 to display a B-mode image, a CFM image, or a power Doppler image on the display unit 16 for a desired section, observe the image, and diagnose a lesion. Since the abnormality of the sampling data does not affect the Doppler image data, the quality of the CFM image and the power Doppler image is good.

In displaying a CFM image or a power Doppler image, a B-mode image and a CFM image (or a power Doppler image) are combined, and, for example, as shown in FIG. Or, a power Doppler image) 162 is displayed in a superimposed manner, and a state such as a blood flow is diagnosed in association with the in-vivo tissue tomographic image.

The tomographic image 160 of the tissue is monochrome (monoc).
hrome) displayed as an image. The CFM image (or power Doppler image) 162 is displayed as a color image. C
In the FM image, for example, the directions of blood flow opposite to each other are represented by red and blue, the brightness indicates the flow velocity, and the degree of mixing of green indicates the dispersion of the flow velocity. Power Doppler image
For example, it is displayed in a pink (pink) color, and the signal intensity is indicated by its luminance. At this time, the color bar (color ba
r) 164 is displayed at the same time as a reference for reading the flow velocity (or signal intensity) from the CFM image (or power Doppler image) 162. In addition,
When displaying only the B-mode image, the color bar 164
To gray scale.

[0064]

As described in detail above, according to the present invention, a sampling data processing method and apparatus for identifying and correcting abnormal data, and an ultrasonic imaging apparatus equipped with such a sampling data processing apparatus The device can be realized.

[Brief description of the drawings]

FIG. 1 is a block diagram of a device according to an example of an embodiment of the present invention.

FIG. 2 is a block diagram of a transmission / reception unit in the device according to an embodiment of the present invention;

FIG. 3 is a conceptual diagram of sound ray scanning performed by the apparatus according to the embodiment of the present invention;

FIG. 4 is a block diagram of a B-mode processing unit in the apparatus according to the embodiment of the present invention;

FIG. 5 is a block diagram of a Doppler processing unit in the apparatus according to the embodiment of the present invention;

FIG. 6 is a block diagram of an image processing unit in the apparatus according to the embodiment of the present invention;

FIG. 7 is a block diagram of a preprocessing circuit in the device according to an example of the embodiment of the present invention;

FIG. 8 is a diagram illustrating forward prediction and backward prediction in the apparatus according to an example of the embodiment of the present invention.

FIG. 9 is a schematic diagram of a display image in the device according to an example of the embodiment of the present invention.

[Explanation of symbols]

 2 Ultrasonic probe 4 Subject 6 Transmission / reception unit 12 Doppler processing unit 14 Image processing unit 16 Display unit 18 Control unit 20 Operation unit 602 Transmission timing generation circuit 604 Transmission beam former 606 Transmission / reception switching circuit 608 Selector 610 Receiving beam former 102 Logarithmic amplification circuit 104 Envelope detection circuit 120 Quadrature detection circuit 122 Preprocessing circuit 124 MTI filter 126 Autocorrelation circuit 128 Average flow velocity calculation circuit 130 Distributed calculation circuit 132 Power calculation circuit 140 Bus 142 Sound ray data memory 144 Digital scan converter 146 Image Memory 148 Image processor 200 Radiation point 202 Sound ray 204 Circular arc 206 Two-dimensional area 208 Divergence point 150 Sampling circuit 152 Buffer memory 154 Sample value correction processor 160 Tissue tomographic image 162 CFM image 164 Color bar

Claims (3)

[Claims] 1. A method comprising: sampling a plurality of data; determining a value based on a predicted value obtained by predicting a value of each of the plurality of data; and correcting a value determined to be abnormal. Sampling data processing method. 2. A sampling means for sampling a plurality of data, a judging means for judging based on a predicted value obtained by estimating a value of each of the plurality of data obtained by the sampling means; Correction means for correcting a value determined by the means to be abnormal. 3. A transmission / reception means for transmitting an ultrasonic wave to a subject to receive an echo, a sampling means for sampling an echo signal received by the transmission / reception means, and a plurality of data of each of the plurality of data obtained by the sampling means. Determining means for determining based on a predicted value obtained by predicting a value; correcting means for correcting a value determined to be abnormal by the determining means; and Doppler processing using the plurality of corrected data. An ultrasonic imaging apparatus comprising: a Doppler processing unit that performs