JPH0731615A - Image data processing method and apparatus for ultrasonic diagnostic apparatus - Google Patents

Abstract

PURPOSE:To enable efficient detection by performing an opposite.conversion of data converted normally with a time frequency axis being center shifted to obtain an ultrasonic image. CONSTITUTION:An RF echo data from a subject is outputted from an RF signal detecting section 10 and enters a normal conversion section 12 to be converted normally. Image data turned to a transform domain by a normal conversion enters a compression section 13 and undergoes a compression processing. Image data compessed are preserved temporarily into a frame memory 14. A center shift opposite conversion section 15 reads the image data out of the frame memory 14 to perform an opposite conversion with a time frequency axis center shifted as reference. The opposite conversion also serves as action of detection. The image converted oppositely is stored into a B-mode image generation section 16. An MTI processing section 17 calculates a difference between image compression data and preceding frame data and resulting difference information is converted oppositely with the opposite conversion section 18.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image data processing method and apparatus for an ultrasonic diagnostic apparatus, and more particularly to an image data processing method and apparatus which can also serve as image data compression.

[0002]

2. Description of the Related Art An ultrasonic diagnostic apparatus is designed such that an ultrasonic probe (probe) is brought into contact with a diseased part of a subject and the frequency is from 1 MHz to a dozen MHz.
Of the same, the reflected echo signal reflected from different regions of the acoustic impedance of the affected area is received by the same ultrasonic probe, after performing phase adjustment, etc., image processing and display of the subject It is a device for displaying an image in A mode, B mode or M mode display.

FIG. 5 is a block diagram showing a configuration example of a conventional system, showing an image processing system. RF (Radio Freq) received by an ultrasonic probe (not shown)
The echo signal enters the receiving beamformer 1. In the receiving beam former 1, the phases of the received signals corresponding to the respective oscillating elements are adjusted and then added. The reflected echo signal that has been phased and added by the receiving beamformer 1 is logarithmically compressed by the logarithmic amplifier 2 and then enters the wave detector 3.

The detector 3 detects the input reflected echo signal and removes the high frequency component of 1 MHz to tens of MHz.
The output of the detector 3 from which the high frequency components have been removed is the A / D
It enters the converter 4 and is converted into digital data. The reflected echo signal converted into digital data is stored in the memory 5
Will be temporarily stored in. Here, the reflected echo signal stored in the memory 5 is data that has not been converted in the scanning direction.

The data stored in the memory 5 is read out in order, the scanning direction is converted, and then stored in the B-mode image memory 6. The reflected echo signal stored in the image memory 6 is sent to the display device 7 and displayed.

[0006]

In the conventional system as described above, for example, the RF echo signal after phasing addition for obtaining a B-mode image is subjected to processing such as filter processing, if necessary, and then detected. Then, it is converted into a unipolar echo video signal, further subjected to filter processing and the like, A / D converted, and written in an image memory according to a predetermined procedure or a predetermined arrangement, and when necessary, Scan conversion is performed before or after that, and image processing is performed. Therefore, the work of the detection stage has nothing to do with the subsequent processing on the image memory.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an image data processing method and apparatus for an ultrasonic diagnostic apparatus capable of efficiently performing detection.

[0008]

According to the present invention for solving the above-mentioned problems, first, the RF echo data is forward-transformed (step 1), and the forward-transformed data is inverse-transformed by center-shifting the time-frequency axis. It is characterized in that an ultrasonic image is obtained by carrying out (step 2). Secondly, the RF echo data is forward-transformed (step 1), the forward-transformed data is compressed (step 2), and the compressed data is obtained. Is characterized in that an ultrasonic image is obtained by center-shifting the time-frequency axis and performing inverse transformation (step 3),
Third, the RF echo data is forward-converted (step 1), the forward-converted data is subjected to MTI processing (step 2), and the MTI is processed.
Inverse conversion is performed on the processed data (step 3)
Fourth, the RF echo data is forward-transformed (step 1), the forward-transformed data is compressed (step 2), the compressed data is MTI-processed (step 3), and the MTI-processed data is obtained. The reverse conversion is performed (step 4).

[0009]

According to the first aspect of the invention, when the forward-converted RF echo signal is inversely converted, the time-frequency axis is center-shifted to a designated position, and the center-shifted position is used as a reference for inverse conversion. As a result, a certain frequency component is converted into a DC component, which is equivalent to detection.

According to a second aspect of the present invention, after the forward-converted RF echo signal is compressed, the time-frequency axis is center-shifted to a designated position, and inverse conversion is performed with the center-shifted position as a reference. As a result, a certain frequency component is converted into a DC component, which is equivalent to detection.

These inventions also perform detection in the process of inverse conversion. By taking such a sequence, detection can be performed efficiently.

[0012]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a sequence diagram showing the principle of the method of the present invention, and FIG. 2 is a configuration block diagram showing an embodiment of the present invention. In FIG. 2, reference numeral 10 is an RF signal detector that obtains an ultrasonic signal from the subject. RF echo data is obtained from the RF signal detector 10. Reference numeral 12 is a forward conversion unit that forward-converts the RF echo data, and 13 is a compression unit that compresses the forward-converted data. Here, as a data compression method, for example, a method of thinning out data according to a certain rule, for example, a bin with a small energy is cut off,
Alternatively, a method of allocating a small amount of bits is used.

Reference numeral 14 is a frame memory for temporarily storing the forward conversion data thus obtained. The data stored in the frame memory 14 may be stored in a storage device such as an optical disk.
Since the image data stored in the frame memory 14 is compressed, many frame images can be stored in the storage device (not shown).
Further, even when the image data stored in the frame memory 14 is transferred, the data transfer efficiency is improved because the data amount is small.

Reference numeral 15 denotes a center shift inverse conversion unit which performs center conversion on the time-frequency axis of the image data stored in the frame memory 14 by a predetermined amount, and then performs inverse conversion around the shifted point. Reference numeral 16 denotes a B-mode image generation unit that stores the inversely-converted B-mode image data.

Reference numeral 17 denotes an MTI processing unit that receives the output of the frame memory 14 and performs MTI processing by obtaining the difference from the previous frame image, and 18 is an inverse conversion unit that inversely converts the output of the MTI processing unit 17. is there. 19 is the inverse transformation unit 18
Is a CFM (color flow mapping) image generation unit that stores the output of 20 is a B-mode image generation unit 1
An adder unit that adds the output of 6 and the output of the CFM image generation unit 19 is a display device such as a CRT that displays the output of the adder unit 20. The operation of the apparatus configured as described above will be described below.

The RF signal detector 10 outputs RF echo data from the subject. This RF echo data enters the forward conversion unit 12 and is forward converted. As a method of this forward conversion, for example, DCT (discrete cosine conversion) is used. The image data that has been forward-converted into the transform domain enters the compression unit 13,
A compression process is performed. As a compression method, for example, thinning out or truncation of a bin having a small energy is used. The compressed image data is temporarily stored in the frame memory 14. If the contents of the frame memory 14 are stored in a storage device such as an optical disk, compressed image data is stored, so that the memory capacity can be reduced. In addition, data transfer improves transfer efficiency.

The center shift inverse transformation section 15 reads out image data from the frame memory 14 and performs inverse transformation (for example, inverse DCT) on the basis of the center-shifted time-frequency axis. This inverse conversion also has a detection function. Hereinafter, the operation of the center shift inverse conversion unit 15 will be described in detail.

First, in the forward conversion unit 12, the phase-matched R has been added.
The F echo data is stored in an image memory, and it is stored locally (for example, 8 × 8, 16 × 1 is used as a local clipping method).
Various methods such as 6, 4 × 16, 1 × 16, etc. are conceivable) Two-dimensional DFT (discrete Fourier transform)
Alternatively, when transforming (transforming) from the real data domain to the spatiotemporal frequency domain by forward transform such as DCT, transform domain data as shown in FIG. 3 is obtained. FIG. 3 is a diagram showing the transform domain after forward conversion in comparison with the image of a general image.
(A) is a digital representation of a general image data image, and (b) is a similar representation of an RF echo image. Each ◯ mark in the figure indicates one pixel. In FIG. 3B, the vertical axis is the spatial frequency (the direction in which the sound rays are arranged), and the horizontal axis is the time frequency (the echo return time). It can be seen that the value of the axis is 0 (DC component) and the frequency becomes higher as it goes away from the origin.

In an image in the transform domain of general image data, the data is distributed around the coordinate origin (0,0) A as shown in (a). here,
Point A represents the direct current component, and as it departs from it,
Region B below (1,0) and (0,1) represents spatial frequency components.

On the other hand, the RF echo component does not include a DC component, and therefore the point A becomes almost 0, and instead, a large component appears at the point C, which means the carrier frequency of ultrasonic waves, and its periphery. The distribution is data symmetrical about the frequency at point C. Therefore, when the center shift inverse transform unit 15 performs the inverse transform process, the origin of the time-frequency axis is shifted in the forward direction (to the right) by an appropriate amount, and the origin when performing the inverse transform is C, and the surrounding component D.
When is converted into the component that carries the actual image information and inversely transformed, a certain frequency component becomes a direct current region in the actual image space, and the frequency shifts. Therefore, it is possible to obtain an effect equivalent to that the detection is performed.

The component D is actually C due to the nature of conversion.
It is not necessary to look at the lower right side of the point, but it may be set at the lower left side. Further, if the domain space is a dead end, it may be folded back and set on the opposite side as shown in FIG. 4 instead of (b) of FIG. In other words, the dead end on the right side should be folded back to the beginning on the left side.

Therefore, in the transform domain, when the point C is regarded as the origin and D is regarded as the component which becomes the real image information, and the time-frequency axis is shifted as shown in FIG. It can be realized by including demodulation from an RF image to a real image. In the transform domain, the data compression (thinning) of the data in the area of the component D can be performed in the same way as in the area of B in normal image processing. Therefore, since the frequency-shifted inverse transform is performed, the amount of information that must be transferred to the center shift inverse transform unit 15 is greatly reduced.

In this way, the center shift inverse conversion unit 1
By frequency-shifting at 5 and performing inverse conversion, a certain frequency component can be made to be in the DC region, and detection can also be performed at the same time. This center shift inverse conversion unit 15
The inverse transform of corresponds to the forward transform of the forward transform unit 12, and if the forward transform unit 12 is a DCT, it becomes an inverse DCT, and the DFT
If it is (discrete Fourier transform), inverse DFT
In the case of DHT (discrete-Hartley conversion), the inverse DHT is obtained. The image thus inversely converted is stored in the B-mode image generation unit 16.

The compressed image data stored in the frame memory 14 is read by the MTI processor 17. The MTI processing unit 17 stores compressed image data for each frame, and calculates the difference between the image data read from the frame memory 14 and the previous frame data. This difference information is inversely converted by the subsequent inverse converter 18,
Converted to a real image. Here, since the data converted by the inverse conversion unit 18 is performed on the image data that has been data-compressed, the amount of data processing is significantly reduced. The image image inversely transformed by the inverse transformation unit 18 is information including a temporal element and is stored in the CFM image generation unit 19. The effective ultrasonic image processed by the MTI processing unit 17 is effective for an image that changes with time such as a blood vessel image and a heart image.

In this way, the image information stored in the B-mode image generating unit 16 and the CFM image generating unit 19 is added by the adding unit 20 and then displayed on the display device 21 such as a CRT.

In the above description, the case where the data subjected to the forward conversion by the forward conversion unit 12 is compressed and then the center shift reverse conversion is performed is taken as an example. However, the present invention is not limited to this, and the data subjected to the forward conversion by the forward conversion unit 12 may be inversely converted by the immediate center shift inverse conversion unit 15. Further, in the above-described embodiment, the case where the data processed by the MTI processor 17 is inversely converted by the inverse converter 18 with respect to the image data compressed after the forward conversion is taken as an example, but the present invention is not limited to this. Not a thing. The forward-converted data may be immediately MTI-processed by the MTI processor 17 and then inverse-converted by the inverse converter 18.

[0027]

As described above in detail, according to the present invention, it is possible to provide an image data processing method and apparatus for an ultrasonic diagnostic apparatus capable of efficiently performing detection.

[Brief description of drawings]

FIG. 1 is a sequence diagram showing the principle of the method of the present invention.

FIG. 2 is a configuration block diagram showing an embodiment of the present invention.

FIG. 3 is a diagram showing a transform domain after forward conversion.

FIG. 4 is another explanatory diagram of a transform domain.

FIG. 5 is a block diagram showing a configuration example of a conventional system.

[Explanation of symbols]

 10 RF signal detection unit 11 RF echo data 12 Forward conversion unit 13 Compression unit 14 Frame memory 15 Center shift inverse conversion unit 16 B mode image generation unit 17 MTI processing unit 18 Inverse conversion unit 19 CFM image generation unit 20 Addition unit 21 Display device

Claims (8)

[Claims] 1. An ultrasonic image is obtained (step 2) by subjecting the RF echo data to forward transformation (step 1), and subjecting the forward transformed data to center transformation of the time-frequency axis for inverse transformation. A method for processing image data of a characteristic ultrasonic diagnostic apparatus. 2. An ultrasonic image by forward transforming RF echo data (step 1), compressing the forward transform data (step 2), and inversely transforming the compressed data by center-shifting the time-frequency axis. (Step 3)
An image data processing method for an ultrasonic diagnostic apparatus characterized by the above. 3. The RF echo data is forward-transformed (step 1), the forward-transformed data is MTI-processed (step 2), and the MTI-processed data is inversely transformed (step 3). Image data processing method for ultrasonic diagnostic apparatus. 4. The RF echo data is forward-transformed (step 1), the forward-transformed data is compressed (step 2), the compressed data is MTI-processed (step 3), and the inverse of the MTI-processed data is performed. An image data processing method for an ultrasonic diagnostic apparatus, characterized in that conversion is performed (step 4). 5. An ultrasonic wave configured by a forward transforming unit that receives the RF echo data and performs a forward transform, and a center shift inverse transforming unit that performs a reverse shift by center shifting the time-frequency axis of the forward-transformed data. Image data processing device of diagnostic device. 6. A forward transforming unit for receiving the RF echo data and performing a forward transform, a compressing unit for compressing the forward transformed data, and a center for performing a reverse transform on the compressed data by center-shifting the time-frequency axis. An image data processing apparatus of an ultrasonic diagnostic apparatus configured by a shift inverse conversion unit. 7. A forward transforming unit that receives RF echo data and performs forward transforming, an MTI processing unit that performs MTI processing on the forward transformed data, and an inverse transforming unit that performs inverse transform on the MTI processed data. An image data processing apparatus of an ultrasonic diagnostic apparatus configured by. 8. A forward conversion unit that receives RF echo data and performs a forward conversion, a compression unit that compresses the forward-converted data, an MTI processing unit that performs an MTI process on the compressed data, and an MTI-processed data. An image data processing apparatus of an ultrasonic diagnostic apparatus, which is configured by an inverse conversion unit that performs inverse conversion with respect to.