JP3400247B2 - Ultrasound diagnostic equipment - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic diagnostic apparatus used for medical diagnosis, and more particularly to an ultrasonic diagnostic apparatus capable of rewriting an ultrasonic tomographic image at a high frame rate.

[0002]

2. Description of the Related Art "Medical Ultrasonic Equipment Handbook" pp. 129-161 (Corona Publishing, 1985) introduces B-mode scanning and M-mode scanning as real-time ultrasonic beam scanning methods. Figure 2
FIG. 3 is an explanatory diagram showing ultrasonic beam formation in B mode scanning and ultrasonic beam formation in M mode scanning. Figure 2 (a)
Shows B mode scanning, and FIG. 2B shows M mode scanning. B
In mode scanning, a two-dimensional tomographic image of an imaging target is obtained while moving the ultrasonic beam. For the sake of simplicity, in FIG. 2A, four ultrasonic beams form one image. The probe sequentially forms ultrasonic beams at positions A, B, C and D. Beam 1, beam 2 ...
Express. If the ultrasonic transmission / reception interval is set to T, new beams are formed at 4T intervals at the position A, for example. The two-dimensional tomographic image of the imaging target is also updated at 4T intervals. On the other hand, the M mode scanning fixes the ultrasonic beam at one position, for example, A. The probe forms an ultrasonic beam with a beam 1, a beam 2, ... Although the ultrasonic beam moving method in FIG. 2A is linear scanning, in addition to this, sector scanning for sending a beam in a fan direction from one fixed position on the aperture and one fixed position away from the aperture are also used. There is convex scanning and the like in which a beam is sent in a fan direction from.

[0003]

The B-mode scanning and the M-mode scanning described above have different advantages. That is, the B-mode scanning has an advantage that a two-dimensional tomographic image of an imaging target can be formed. However, when focusing on one ultrasonic beam position, there is a problem that the change of the imaging target during that period cannot be recognized because the ultrasonic beam update interval is 4T. On the other hand, the M-mode scanning has an advantage that the change of the imaging target at one ultrasonic beam position can be observed at the ultrasonic transmission / reception interval T. However, there is a problem that a two-dimensional tomographic image of the imaging target cannot be constructed. It would be most desirable if a scanning method could be obtained that combines these two advantages.
Therefore, an object of the present invention is to solve these conventional problems, to construct a two-dimensional tomographic image of an imaging target, and to make the ultrasonic beam update interval at one ultrasonic beam position equal to the ultrasonic wave transmission / reception interval. Then, an ultrasonic diagnostic apparatus capable of rewriting a tomographic image at a high frame rate is provided.

[0004]

In order to achieve the above object, the ultrasonic diagnostic apparatus of the present invention is a probe (1 in FIG. 1) including an array element for transmitting and receiving ultrasonic pulses in a subject.
And an aperture selection section (2) for selecting an element for transmitting and receiving ultrasonic waves in the probe (1), and a probe transmission element (1) selected by the aperture selection section (2). And a parallel A / D converter for parallel-analog-to-digital converting signals from the probe receiving element (1) selected by the aperture selection section (2), Same as 4),
A digital delay unit (5) that gives a delay to the output of the parallel A / D conversion unit (4) and a digital addition unit (the same as the digital addition unit that forms an ultrasonic beam by adding the output signals of the digital delay unit (5)). And a scanning method selection unit (7) for instructing the aperture selection unit (2) of two ultrasonic beam scanning methods. When (7) selects the first ultrasonic beam scanning method (for example, B mode), the output of the digital addition section (6) is changed by the switching section (8) to the first storage section (9). ) And the scanning method selection unit (7) selects the second ultrasonic beam scanning method (for example, M mode), the output of the digital addition unit (6) is the switching unit (8). Stored in the second storage unit (same as 10) by the Data and the data of the second storage unit (10) are correlated, and the data of the first storage unit (9) is interpolated using the data of the second storage unit (10). It is characterized in that it has a correlation interpolator (11) and stores the output of the correlation interpolator (11) in the third storage (12). Thereby, a two-dimensional tomographic image of the imaging target can be formed, and the update interval of the ultrasonic beam at one ultrasonic beam position can be made equal to the ultrasonic transmission / reception interval. That is, the two-dimensional tomographic image can be rewritten at a high frame rate.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of an ultrasonic diagnostic apparatus according to the first embodiment of the present invention. In FIG. 1, reference numeral 1 is a probe that transmits an ultrasonic pulse into the subject and receives a reflected wave, 2 is a diameter selection unit that selects an element for transmitting and receiving ultrasonic waves in the probe, and 3 is a probe. A transmitting unit for giving a transmission pulse to the transmitting element of the child, a parallel A / D converting section for analog-digital converting signals from the receiving element of the probe in parallel, and 5 for the parallel A / D converting section 4. A digital delay unit for delaying the output, 6 is a digital adding unit for adding the output signals of the digital delay unit 5 to form an ultrasonic beam, and 7 is a ultrasonic selecting unit for the aperture selecting unit 2. A scanning method selecting section for instructing, 8 a switching section for switching and connecting the output of the digital adding section 6 to the first or second storage section, 9 a first storage section, 10 a second storage section, and 11 a second storage section. The correlation calculation between the data in the first storage unit 9 and the data in the second storage unit 10 is performed. Utotomoni, first correlation interpolation unit for interpolating the data storage unit 9 with the data of the second storage unit 10, 12 denotes a third storage unit for storing the output of the correlation interpolation section 11.

The scanning method selection unit 7 firstly includes the aperture selection unit 2.
For B mode scanning. Here, FIG. 2 (a)
Since the operation is described by using, the number of ultrasonic wave transmission / reception required to form one tomographic image is set to 4. Figure 2
In order to form the transmitted beam at the position A in (a), the wave-transmitting unit 3 applies a pulse (pulse voltage) to the transmitting element group selected by the aperture selecting unit 2. When the reception element group selected by the aperture selection unit 2 receives the reflection signal from the imaging target, the parallel A / D conversion unit 4 performs A / D conversion for each element. The transmitting element group and the receiving element group selected by the aperture selection unit 2 do not have to match. For example, there is no problem even if a small-diameter transmitting element transmits and a large-aperture receiving element receives, or a large-aperture transmitting element transmits and a small-aperture receiving element receives. The A / D-converted signals are given a focusing delay by the digital delay unit 5, and then added by the digital addition unit 6 to form a received beam at the position A. Digital adder 6
The output of is connected to the first storage unit 9 by the switching unit 8. By the above operation, the reflection signal at the ultrasonic beam position A is stored in the first storage unit 9. The aperture selection unit 2 sequentially switches the transmission / reception element group and repeats the same operation as described above to form ultrasonic beams at the positions B, C, and D, and store the reflected signal in the first storage unit 9. . As a result, the data necessary to compose one tomographic image is the first
It is stored in the storage unit 9 of.

FIG. 3 is a diagram of data stored in the first storage section during B mode scanning in FIG. The user of the apparatus repeatedly stores the reflection signals at the ultrasonic beam positions A, B, C, and D in the first storage unit 9 so as to configure a tomographic image corresponding to the time he / she wants to observe the imaging target. All data are stored in the first storage unit 9. Here, A → B → C → D → A
It is assumed that the data necessary for constructing three tomographic images in the order of B, C, D, A, B, C, and D are stored. In the data arrangement in the first storage unit 9 at this time, as shown in FIG. 3, reflection data A to D are arranged three times each. Here, the stored reflection signals are s1 to s12. If the number of data of one reflected signal is N, the total number of data of the first storage unit 9 is 12N.
Is. For example, the reflection signals at position A are s1, s5, s
9, the reflection signals at the position B are s2, s6, and s10.
When s1, s2, s3, and s4 are brightness-modulated and two-dimensionally displayed, a first tomographic image is obtained, and when s5, s6, s7, and s8 are brightness-modulated and two-dimensionally displayed, a second tomographic image is obtained.
This tomographic image is generally called a B-mode image. Assuming that the ultrasonic transmission / reception interval is T, the time interval between the reflection signals (for example, s1, s5, and s9 at the position A) between the tomographic images is 4T. When the time interval is 4T, the change between them is unknown. Therefore, in the present invention, the time interval of the reflection signal at the same position between the tomographic images is set to T by the data interpolation using the correlation, and the tomographic image is rewritten at high speed. ,
High frame rate.

FIG. 4 is a diagram of a B-mode matrix created from the data in the first storage section shown in FIG. When 12N data is stored in the first storage unit 9, the correlation interpolation unit 1
1 converts the reflection signal data stored in the first storage unit 9 into a matrix for each position of the ultrasonic beam. The conversion method at the position A is shown in FIG. s1, s5, s9 are converted into a matrix of 9 rows and N columns by zero-padding. The converted matrix is stored again in the first storage unit 9. This matrix will be referred to as a B-mode matrix in the following description. The B-mode matrix is
The reflection signals at the position A are arranged in the row direction at time intervals T. The zero-padded row is the reflected signal at the time when there is no data. Similarly, at the positions B, C and D, a B mode matrix is created. For example, in the B-mode matrix at position B, s1, s5, s9 are s2, s in FIG.
6 and s10. Generally, when the number of data of one reflection signal is N, the number of stored tomographic images is L, and the time interval of the reflection signals at the same position between the tomographic images is KT, the size of the B-mode matrix is K · (L− 1) +1 row and N column. Next, the scanning method selection unit 7 specifies the M mode scanning for the aperture selection unit 2. This operation can be executed in parallel with the matrix conversion in the first storage unit 9. That is, after the B mode scanning is performed, the matrix conversion of the first storage unit 9 is performed in parallel with the M conversion.
Perform mode scan. Alternatively, it may be executed before the matrix conversion in the first storage unit 9. That is, B
After performing the mode scan, the M mode scan may be performed, and then the B mode matrix may be created.

FIG. 5 is an explanatory diagram of data stored in the second storage section during M mode scanning. Position A in FIG. 2B
The transmitting unit 3 gives a launch pulse to the transmitting element group selected by the aperture selecting unit 2 so as to form a transmitting beam. After that, the operations of the parallel A / D converter 4, the digital delay unit 5, and the digital adder 6 are exactly the same as those in the B mode scanning. The output of the digital addition unit 6 is connected to the second storage unit 10 by the switching unit 8, and the reflection signal at the ultrasonic beam position A is stored in the second storage unit 10.
The number of data of the reflection signal is N, which is the same as in the B mode scanning. Because of the M mode scanning, the aperture selecting unit 2 fixes the transmitting and receiving element group and repeats the same operation, and from the time interval (here, 8T) between the first row and the last row of the B mode matrix at the position A shown in FIG. The reflected signal at the position A is stored in the second storage unit 10 for a sufficiently long time. Here, it is assumed that 160 reflected signals are stored. The data arrangement in the second storage unit 10 at this time is as shown in FIG. Here, the stored reflection signals are r1 to r16.
Set to 0. Therefore, the total number of data in the second storage unit 10 is 1
It is 60N. When r1 to r160 are brightness-modulated and two-dimensionally displayed, a tomographic image generally called an M-mode image can be formed at the position A. The time interval between adjacent reflection signals in FIG. 5 is T.

FIG. 6 is a diagram of an M-mode matrix created from the data in the second storage section in FIG. When 160N data is stored in the second storage unit 10, the correlation interpolation unit 11 next converts the reflected signal data stored in the second storage unit 10 into a matrix of 160 rows and N columns. The converted matrix is again stored in the second storage unit 10. This matrix will be referred to as an M-mode matrix in the following description. The M-mode matrix is B
Similar to the mode matrix, the reflection signals at position A are arranged in the row direction at time intervals T. The difference from the B-mode matrix is
The point is that there is no zero-padded row because data exists at all times for each T. Generally, when the number of data of one reflection signal is N and the number of reflection signals of M mode scanning stored at one ultrasonic beam position is K, the size of the M mode matrix is K rows and N columns. After creating the M-mode matrix at position A, the reflected signals 160 at positions B, C, D
The book is similarly stored in the second storage unit 10 and the M-mode matrix at each position is created. As a result, two matrices necessary for increasing the frame rate of the tomographic image are stored in the first storage unit 9.
And prepared in the second storage unit 10. Here, the correlation interpolation unit 11 calculates the correlation between the two matrices. Taking position A as an example, B
The elements of the mode matrix are Bij, and the elements of the M mode matrix are Mi.
Let j. The correlation interpolator 11 calculates the correlation coefficient between matrices by the following equation (1).

[Equation 1] Here, a is an integer of 0 ≦ a ≦ 151, and the correlation coefficient is calculated for each a. In equation (1), Σ before is the integration of the values in the first row to ninth row in FIG. 4, and Σ is the first column to N in FIG.
The integration of the column values, B _ij, is the element of the B-mode matrix of FIG. 4, M _{(i + a) j} is the element of the M-mode matrix of FIG.
Since there are 160 rows of modes, by setting a = 0 to 151, both elements are multiplied and moved while the B-mode matrix moves row by row on the M-mode matrix having a size of about 18 times. The sum of element products for each is calculated.

FIG. 7 is a diagram showing the correlation calculation of the B-mode matrix and the M-mode matrix, and FIG. 8 is a diagram showing the method of interpolating the B-mode matrix with the M-mode matrix. The correlation calculation of the above equation (1) is schematically shown in FIG. First, as shown in FIG. 7, the M-mode matrix and the B-mode matrix are superposed so that the column numbers are the same, and then the B-mode matrix is moved one by one in the row direction. Seeking the sum of element products. For example, when a = 100, it is assumed that the correlation calculation result of the above equation (1) is maximized. At this time, the B-mode matrix is interpolated using the M-mode matrix by the method shown in FIG. In FIG. 8, each element of the zero-setting row of the B-mode matrix is replaced with each element of the M-mode matrix of the multiplication partner at the position where the correlation coefficient is maximum.
That is, the next zero-padded row of s1 is set to r102 and s1
The zero padding row two rows below is replaced with r103, and the zero padding row before s5 is replaced with r104. In FIG. 8, the first, fifth, and ninth rows of the B-mode matrix after interpolation are s
1, s5, s9, but (s1 + r101) / 2
It is also possible to set (s5 + r105) / 2, (s9 + r109) / 2. The interpolated B-mode matrix is stored in the third storage unit 12. Also, instead of using each element of the M-mode matrix of the multiplication partner at the location where the correlation coefficient is maximum, each element of the two M-mode matrices at the location having the maximum correlation coefficient and the second largest location is used. It is also possible. This means that, for example, the maximum correlation coefficient is a = 100,
When the second largest part is a = 50, B after interpolation
The second row of the mode matrix is (r102 + r52) / 2, and the third row is (r103 + r53) / 2.

By the above, the interpolation of the B-mode matrix at the position A is completed. B at positions B, C, D in a similar manner
The mode matrix is also interpolated. As a result, three new tomographic images are newly inserted between the first tomographic image and the second tomographic image in FIG. 3 between the second tomographic image and the third tomographic image, respectively. The data necessary for forming a total of 9 tomographic images are stored in the third storage unit 12. In these nine tomographic images, since the time interval of the reflection signal at the same position between the tomographic images is T, it is possible to obtain a tomographic image with a high frame rate by displaying with luminance modulation. Further, in the above formula (1), the column elements are matched and the correlation between the B-mode matrix and the M-mode matrix is calculated, but as another method, the B-mode matrix can be moved in the column direction to calculate the correlation. Is. The calculation formula in this case is shown in the following formula (2).

[Equation 2] Here, the range of a is the same as that of the previous expression (1), and b is -N.
It is an integer of + 1 ≦ b ≦ N−1. That is, first, the B-mode matrix is arranged on the left side of the M-mode matrix of the same row number at a position where the B-mode matrix is overlapped by one column, and is sequentially moved to the right by one column. Then, the B-mode matrix is moved to the right side of the M-mode matrix to a position where only one column is overlapped, and the sum of element products is calculated for each movement. The first column number to be multiplied in the B-mode matrix is max (1,1-b),
The last column number is min (N, N-b). Next, as in the previous expression (1), while moving the B-mode matrix row by row in the row direction, the above-mentioned column direction movement is performed to obtain the sum of element products for each movement. This calculation method is used when the parallel movement of the imaging target in the depth direction is not considered. Also in the case of using the above equation (2), the value newly assigned to each element of the zero-setting row of the B-mode matrix is each element of the M-mode matrix of the multiplication partner at the position where the correlation coefficient becomes the maximum.

The above-described interpolation method assumes that the reflection signals at the positions of the ultrasonic beams of the imaged object repeat the same change periodically. In other words, it is premised that the same reflection signal pattern as the B-mode matrix created first appears in the M-mode matrix created from the reflection signals acquired by performing M-mode scanning for a sufficiently long time. Heartbeat and respiration are typical cycles in the living body.

FIG. 9 is a block diagram of an ultrasonic diagnostic apparatus according to the second embodiment of the present invention. In FIG. 9, 1 is a probe, 2 is a diameter selection unit, 3 is a wave transmission unit, 7 is a scanning method selection unit, 8 is a switching unit, 9 is a first storage unit, 10 is a second storage unit, Reference numeral 11 is a correlation interpolation unit, 12 is a third storage unit, 13 is an analog delay unit, 14 is an analog addition unit, and 15 is an A / D conversion unit 15. In the diagnostic device of FIG. 1, all the element signals of the probe 1 are digitized and the subsequent signal processing is digitally performed, whereas in the diagnostic device of FIG. 9, the ultrasonic beam is not formed by addition. This is performed by analog signal processing, and then the digital signal processing. In this method, the analog signal is processed as it is before the interpolation processing is started. However, since the interpolation processing is digital processing, there is no difference in accuracy from the above method. Therefore,
The algorithm for obtaining a high frame rate tomographic image is exactly the same as that of the diagnostic apparatus in FIG. In the above embodiments, linear scanning is taken as an example of the beam moving method, but other than that, there are sector scanning and convex scanning.
It is obvious that the present invention can be applied to these as well. Note that sector scanning is a method of transmitting ultrasonic beams in the fan direction from transmitting / receiving elements at the same position, and convex scanning is a method of transmitting beams in the fan direction while moving the transmitting / receiving elements arranged in an arc shape. Is. It is also possible to divide the address and use the first storage unit 9, the second storage unit 10, and the third storage unit 12 as a common digital memory. The effect of the present invention for realizing a high frame rate is determined by the number of rasters forming a tomographic image. For example, when one image is formed by 128 rasters, rewriting by 128 times is performed. If the number of rasters is 64 and 300, 64 times and 3 respectively.
The effect of 00 times can be obtained.

[0015]

As described above, according to the present invention,
In an ultrasonic diagnostic apparatus that forms a tomographic image of an imaging target,
By interpolating the signal obtained in the B mode scanning from the correlation calculation of the signal obtained in the M mode scanning and the signal obtained in the B mode scanning, the screen is rewritten at the ultrasonic transmission / reception intervals to achieve a high frame rate. A sound wave diagnostic apparatus can be realized.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an ultrasonic diagnostic apparatus showing a first embodiment of the present invention.

FIG. 2 is a diagram showing ultrasonic beam formation in B mode scanning and ultrasonic beam formation in M mode scanning.

FIG. 3 is a diagram showing data stored in a first storage unit during B mode scanning.

FIG. 4 is a diagram of a B-mode matrix created from the data in the first storage unit in FIG.

FIG. 5 is a diagram showing data stored in a second storage unit during M mode scanning.

FIG. 6 is a diagram of an M-mode matrix created from the data in the second storage unit in FIG.

FIG. 7 is a diagram showing a correlation calculation of a B-mode matrix and an M-mode matrix.

FIG. 8 is a diagram illustrating a method of interpolating a B-mode matrix with an M-mode matrix.

FIG. 9 is a configuration diagram of an ultrasonic diagnostic apparatus showing a second embodiment of the present invention.

[Explanation of symbols]

1 ... Probe, 2 ... Caliber selection part, 3 ... Wave transmission part, 4 ... Parallel A
/ D conversion unit, 5 ... Digital delay unit, 6 ... Digital addition unit, 7 ... Scan method selection unit, 8 ... Switching unit, 9 ... First storage unit, 10 ... Second storage unit, 11 ... Correlation interpolation unit , 12 ...
Third storage unit, 13 ... Analog delay unit, 14 ... Analog addition unit, 15 ... A / D conversion unit, s1 to s12 ... Reflection signal in B mode scanning, r1 to r160 ... Reflection signal in M mode scanning.

Continuation of front page (56) Reference JP-A-56-8041 (JP, A) JP-A-2-98344 (JP, A) JP-A-2-257943 (JP, A) JP-A-5-118821 (JP , A) (58) Fields investigated (Int.Cl. ⁷ , DB name) A61B 8/00

Claims (2)

(57) [Claims] 1. A probe comprising an array element for transmitting and receiving ultrasonic pulses in a subject, a caliber selecting section for selecting an element for transmitting and receiving ultrasonic waves in the probe, and selection by the caliber selecting section. And a parallel transmission circuit for analog-digital converting signals from the probe receiving element selected by the aperture selecting section in parallel to the transmitting section for applying a transmission pulse to the selected probe transmitting element.
An ultrasonic wave including an A / D conversion unit, a digital delay unit that delays an output of the parallel A / D conversion unit, and a digital addition unit that adds an output signal of the digital delay unit to form an ultrasonic beam. In the diagnostic device, a B-mode scanning method for obtaining a two-dimensional tomographic image of an imaging object while moving the ultrasonic beam with respect to the aperture selection unit, or an M-mode scanning for scanning the ultrasonic beam while fixing it at one position A scanning method selecting section for instructing a method, a first storage section for storing an output of the digital adding section when the scanning method selecting section selects the B-mode scanning method, and the scanning method selecting section. When the M-mode scanning method is selected, the correlation calculation between the second storage unit that stores the output of the digital addition unit and the data of the first storage unit and the data of the second storage unit is performed. With the implementation An ultrasonic diagnostic device comprising: a correlation interpolating unit that interpolates data of the first storage unit using data of the second storage unit; and a third storage unit that stores an output of the correlation interpolating unit. apparatus. 2. A probe comprising an array element for transmitting and receiving ultrasonic pulses within a subject, a caliber selecting section for selecting an element for transmitting and receiving ultrasonic waves in the probe, and selection by the caliber selecting section. Transmitting section for giving a transmission pulse to the probe transmitting element thus selected, an analog delay section for delaying a signal from the probe receiving element selected by the aperture selecting section, and an output signal of the analog delay section Is added to form an ultrasonic beam, and the output of the analog addition unit
In an ultrasonic diagnostic apparatus including an A / D conversion unit for digital conversion, a B-mode scanning method for obtaining a two-dimensional tomographic image of an imaging target while moving an ultrasonic beam to the aperture selection unit, or the ultrasonic wave A scanning method selecting section for instructing an M mode scanning method for fixing the beam at one position and scanning, and an output of the A / D converting section when the scanning method selecting section selects the B mode scanning method. A first storage unit that stores the output, a second storage unit that stores the output of the A / D conversion unit when the scanning method selection unit selects the M-mode scanning method, and A correlation interpolator that performs a correlation operation between the data in the storage unit and the data in the second storage unit, and interpolates the data in the first storage unit using the data in the second storage unit; And a third storage unit for storing the output of the correlation interpolator. Ultrasonic diagnostic apparatus according to claim.