JPH04276244A - Ultrasound diagnostic equipment - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

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, and more particularly to an ultrasonic diagnostic apparatus capable of simultaneously displaying a B-mode image and a Doppler-mode image on a monitor.

0002

2. Description of the Related Art Ultrasonic diagnostic equipment used in the medical field displays, for example, tomographic data (B-mode images) of the heart on a monitor in real time, or measures blood flow velocity in a specific region using the pulsed Doppler method. This distribution (Doppler mode image) is displayed on a monitor in the same manner as described above. In such an ultrasound diagnostic apparatus, a mode (B/D mode) in which two images, a B mode image and a Doppler mode image, are displayed on one monitor may be set.

Generally, in the B/D mode, a pulse for the B mode and a pulse for the Doppler mode are alternately emitted for each pulse. However, if a pulse for B mode and Doppler mode is emitted every pulse like this, the repetition rate in Doppler mode becomes slow,
There is a problem that good Doppler mode images cannot be obtained. Therefore, in recent ultrasonic diagnostic apparatuses, a transmission pulse for B mode is continuously transmitted for one frame, and then a transmission pulse for Doppler mode is emitted. With such a wave transmission method, the repetition rate in Doppler mode is increased, and a good Doppler mode image can be obtained.

0004

[Problems to be Solved by the Invention] As mentioned above, in the method of continuously transmitting an ultrasound beam for one frame of B mode and then transmitting an ultrasound beam for Doppler mode,
No Doppler signal is obtained during B-mode operation, and Doppler images are interrupted during this period. This missing part of the Doppler signal is explained in the literature (“A Time-Shar
ed Ultrasound Doppler Mea
surement and 2-D imaging
System”, KJELL KRISTFFERSE
N etal, IEEE. Trans. Bio. Eng
．． vol. 35. No. 5. May. The MSE method (Missing Sig. 1988)
nal estimation) has been proposed and is actually being studied. This MSE method is a method of interpolating the Doppler signal of the missing portion by using a signal of a steady portion for a predetermined period before the missing portion of the Doppler signal.

However, the MSE method is based on the assumption that the missing portion of data is statistically the same as the previous data, and this assumption only holds true when the missing period is 10 ms.
That's about it. Therefore, when predicting Doppler signal missing parts using the conventional MSE method, only a period of about 10 ms can be allocated as the period of the B-mode transmission pulse, and one B-mode frame like the adult abdomen or heart can be allocated. If the time required for this is long, only about 50 transmission beams can be emitted. A transmission beam of this level results in an image in a narrow range or a coarse image, and there is a problem in that an image effective for diagnosis cannot be obtained. Furthermore, in areas where the Doppler signal changes quickly, the steady period is short, so the range that can be predicted is narrowed, and data cannot be predicted for all missing parts.

[0006] An object of the present invention is to provide an ultrasonic diagnostic apparatus that is capable of predicting signals even in areas where the Doppler signal is missing in areas where the time required for one B-mode frame is long and the Doppler signal changes quickly. There is a particular thing.

[0007]

[Means for Solving the Problems] The ultrasonic diagnostic apparatus according to the present invention continuously transmits an ultrasound beam for one frame in B mode, and then transmits an ultrasound beam for Doppler mode. This device is capable of simultaneously displaying a mode image and a Doppler mode image on a monitor, and includes forward prediction means, backward prediction means, and data addition means.

[0008] The forward prediction means is a means for predicting the data of the first half of the missing portion of the Doppler mode missing portion during B-mode ultrasound beam transmission from data obtained a predetermined period before the missing portion. The backward prediction means is a means for predicting data in the latter half of the missing Doppler data portion from data that is a predetermined period after the missing portion. The data adding means is a means for adding the prediction data obtained by each prediction means and the Doppler data obtained from the reflected echo of the Doppler mode ultrasound beam.

[0009]

[Operation] The ultrasound diagnostic apparatus of the present invention continuously transmits an ultrasound beam for one frame in B mode, and then transmits an ultrasound beam for Doppler mode, thereby producing a B mode image and a Doppler mode image. displayed simultaneously on the monitor. At this time, Doppler mode data cannot be obtained during the period in which the B mode ultrasound beam is emitted, resulting in a missing portion. Regarding this Doppler mode missing part, the forward prediction means predicts the data in the first half of the missing part from data from a predetermined period before the missing part, and the backward prediction means predicts the data for the first half of the missing part from data after a predetermined period from the missing part. Data for the second half is predicted. Then, the forward prediction data, the backward prediction data, and the Doppler data obtained from the reflected echo of the Doppler mode ultrasound beam are added by the data addition means, and a Doppler mode image is obtained based on these data.

[0010] In this way, since missing parts of Doppler data are interpolated by not only forward prediction but also backward prediction, long missing parts can be smoothly connected, and a good B-mode image can be obtained in B/D mode. At the same time, Doppler data can also be obtained for areas where the Doppler signal changes quickly.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing a schematic configuration of an ultrasonic diagnostic apparatus according to an embodiment of the present invention. The probe 1 is composed of a plurality of micro oscillators, and the wave transmitting/receiving circuit 2
It is connected to the. The transmitting/receiving circuit 2 includes a high frequency pulse oscillator for transmitting an ultrasonic beam, a receiver for receiving and processing reflected echoes, a delay circuit and a delay amount selection circuit for performing electronic scanning, and the like. The wave transmitting/receiving circuit 2 includes an oscillator (OSC) that generates a reference wave signal as a standard.
3 is connected. Further, the wave transmitting/receiving circuit 2 is connected to a Doppler signal processing system 4 and a tomographic signal processing circuit 5 for B mode.

The Doppler signal processing system 4 has mixers 6 and 7. The output of the wave transmitting/receiving circuit 2 and the output of a 90° phase shifter 30 that shifts the phase of the oscillator 3 by 90 degrees are input to the mixer 6, and the mixer 7 receives the output of the wave transmitting/receiving circuit 2 and the output of the oscillator 3. 3 output is input. mixer 6
, 7 perform these mixing operations to obtain Doppler signals.

A/D conversion circuits 8 and 9 and integration circuits 10 and 11 are connected to the mixers 6 and 7, respectively. The A/D conversion circuits 8 and 9 convert the real and imaginary parts of the Doppler signals obtained from the outputs of the mixers 6 and 7 into digital signals. In addition, the integrating circuits 10 and 11 have A/
The outputs of the D conversion circuits 8 and 9 are each integrated at several points in the depth direction to form one piece of data. Integrating circuit 10
, 11 is equipped with a Doppler data creation circuit 2, which will be described later.
0 is connected. Furthermore, MTI filters 12 and 13 are connected to the Doppler data creation circuit 20. MTI
The filters 12 and 13 remove clutter by removing low frequency components of input data and passing high frequency components. The output of each MTI filter 12, 13 is given to an FFT calculation circuit 15. FFT calculation circuit 15
is for calculating a blood flow spectrum at a designated sample position by performing a fast Fourier transform calculation.

On the other hand, the tomographic signal processing circuit 5 is a circuit for obtaining tomographic data (B mode data) of a living body.
It has a detection function, etc. Then, the output of this tomographic signal processing circuit 5 is converted to FFT via an A/D conversion circuit 16.
The output of the arithmetic circuit 15 is applied to a digital scan converter (DSC) 17. The output of the DSC 17 is given to a CRT monitor 18, which displays a B-mode image and a Doppler mode image (blood flow spectrum).
Images such as the following are displayed.

FIG. 2 shows details of the Doppler data creation circuit 20. The Doppler data creation circuit 20 includes a RAM 31 and
A white noise generator 32 that generates white noise, a data prediction calculation circuit 33 that performs forward prediction and backward prediction from the obtained data, and multipliers 34, 35, 36, 37, and 38.
, 39, and adders 40, 41. The RAM 31 sequentially stores the real part ri and the imaginary part Qi of the Doppler signal, and has a capacity capable of storing a signal for a period of about 20 ms. This RAM31 has R.A.
A window function W is applied to the signal read from M31.
Multipliers 34 and 35 for multiplying by i are connected, and the outputs of these multipliers 34 and 35 are input to the data prediction calculation circuit 33. Further, the data prediction calculation circuit 33 receives the white noise generated from the white noise generator 32 as input. Output signal of data prediction calculation circuit 33 and RAM 3
The signals input to 1 are multipliers 36, 37,
38 and 39 are multiplied by coefficients ei and ei' for phase-in and phase-out. Then, each data is added by adders 40 and 41, and is provided to MTI filters 12 and 13.

Next, the operation will be explained. When the device is activated, first, one frame of ultrasonic pulses for B mode are continuously emitted. A reflected echo from inside the living body obtained by this ultrasonic pulse is input to the tomographic signal processing circuit 5 via the wave transmitting/receiving circuit 2. In the tomographic signal processing circuit 5, B-mode tomographic data is obtained through detection processing, etc., and this B-mode tomographic data is input to the DSC 17 via the A/D conversion circuit 16.

Next, ultrasonic pulses for Doppler mode are repeatedly emitted. The reflected echo for this Doppler mode ultrasound pulse is input to the Doppler signal processing system 4,
A Doppler signal is obtained. However, since no Doppler signal is obtained during the B-mode operation as described above, data missing portions occur during a predetermined period as shown in FIG. Regarding this portion, a write prohibition signal is given to the RAM 31 from the control circuit 14, and data is not written to the RAM 31. Then, regarding this data missing portion, the Doppler data generation circuit 20 performs data prediction by forward prediction and backward prediction as described later. The data obtained by this prediction is similar to the conventional MTI
Clutter components are removed by filters 12 and 13,
The signal is input to the FFT calculation circuit 15. The FFT calculation circuit 15 calculates the spectral distribution of blood flow, and the obtained data is displayed on the monitor 18 via the DSC 17.

Next, forward prediction and backward prediction in the Doppler data creation circuit 20 will be explained. First, RAM
N Doppler signals x1 to xN stored in 31 are read out. The real part ri and imaginary part Q of this read data
A multiplier 34 for each of i by a window function Wi
, multiplied by 35. As a result, the data prediction calculation circuit 33 receives the signals hri and hQi. However, hri=ri×Wi hQi=Qi×Wi. On the other hand, from the white noise generator 32, white noise V
rk and VQk are also input, and convolution is performed using these data to obtain predicted data for the real and imaginary parts. Regarding this data prediction calculation,
The above document (“ATime-Shared Ultras
ound Doppler Measurement
and 2-D imaging System”,K
JELLKRISTFFERSEN etal, IEE
E. Trans. Bio. Eng. vol. 35. No
．． 5. May. (1988), as stated in
This is possible using equation 1.

[0019]

[Math 1]

[0020] The output is the real part of the predicted data,
The imaginary parts are obtained respectively. Next, regarding the latter half of the missing part, the Doppler signal xN'~ shown in FIG.
x1' is read out in this order, that is, data is read out with the time axis reversed, and convolution integration is performed using the white noise from the white noise generator 32 in the same manner as described above to perform backward prediction.

The predicted data thus obtained are multiplied by the coefficient ei' in multipliers 36 and 37 to perform phase-out processing, and are input to adders 40 and 41. On the other hand, the Doppler signal of the reflected echo signal obtained by the ultrasound beam in the Doppler mode is transmitted to the multipliers 38 and 3.
9 is multiplied by the coefficient ei and subjected to phase-in processing,
It is input to adders 40 and 41. In this way, the Doppler data actually obtained and the predicted data obtained by forward prediction and backward prediction are added and output to the MTI filters 12 and 13.

In such an embodiment, the first half of the Doppler data output portion is estimated by forward prediction, and the second half is estimated by backward prediction, so even if the data missing portion is 20 ms or more, the stability is maintained. Predicted data can be obtained by making predictions using the obtained data. Therefore, even when the B/D mode is selected in the B mode with a large depth of field in which the Doppler signal is largely missing, the Doppler signal is displayed continuously, eliminating unnaturalness.

[0023]

As described above, in the present invention, the data of the missing portion of the Doppler signal is estimated by forward prediction and backward prediction, so that the time required for one B-mode frame, such as the abdomen or heart of an adult, is reduced. Even in a long region where the Doppler signal changes rapidly, stable estimation data can be obtained for the missing portion of the Doppler signal, and good B-mode images and Doppler images can be obtained at the same time.

[Brief explanation of the drawing]

FIG. 1 is a block configuration diagram of an ultrasonic diagnostic apparatus according to an embodiment of the present invention.

FIG. 2 is a block configuration diagram of a Doppler data creation circuit of the apparatus.

FIG. 3 is a diagram showing Doppler data and RAM contents in the Doppler data creation circuit.

[Explanation of symbols]

14 Control circuit 20 Doppler data creation circuit 31 RAM 32 White noise generator 33 Data prediction calculation circuit

Claims (1)

[Claims] Claim 1: After continuously transmitting an ultrasound beam for one frame in B mode, an ultrasound beam for Doppler mode is transmitted, and a B mode image and a Doppler mode image can be displayed simultaneously on a monitor. In the ultrasonic diagnostic apparatus, with respect to a missing portion of Doppler data during B-mode ultrasound beam transmission, a forward prediction means for predicting data in the first half of the missing portion from data obtained a predetermined period before the missing portion; and the Doppler data. Regarding the missing part, there is a backward prediction means for predicting the latter half of the missing part from data after a predetermined period from the missing part, and a backward prediction means for predicting data in the latter half of the missing part from data after a predetermined period from the missing part; An ultrasonic diagnostic apparatus comprising: data addition means for adding the Doppler data obtained by the data.