JPH04336055A - Ultrasonic doppler image device - Google Patents

Abstract

PURPOSE:To prevent discontinuous data from being contained in blood flow information. CONSTITUTION:A Doppler deviation signal is detected by a phase detector 3 by means of an echo signal detected by a probe 1. When a blood flow component is fetched from a Doppler deviation signal this detected signal is considered as a blood flow signal containing clutter from the Doppler deviation signal, so as to seek for amplitude, the phase, and the rotation angle of a blood flow signal by means of a clutter information computer 5, and a result is approximated by a sine wave of a monfrequency. Further, based on an approximate value, data remaining in an MTI filter 7 during input to the filter is determined. The data is set as preset data in the MTI filter 7 and the occurrence of transient turbulence of the MTI filter is reduced.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to an ultrasound Doppler imaging device, and in particular, a medical ultrasound device suitable for transmitting ultrasound waves into a subject and displaying blood flow information based on echo signals reflected from the body. The present invention relates to a sonic Doppler imaging device.

0002

[Prior Art] Ultrasonic Doppler imaging devices are capable of displaying blood flow information by utilizing the fact that the echoes of ultrasound pulses transmitted into the body cause a Doppler shift with respect to moving objects. As a conventional device of this kind, one shown in FIG. 4 is known. The device shown in FIG. 4 includes a probe 101, a transceiver 102, a phase detector 103, an A/
It includes a D converter 104, an MTI filter 105, a blood flow information calculation means 106, and a display 107. When this device displays blood flow information, ultrasonic pulses are transmitted from the transceiver 102 into the subject's body via the probe 101, and the transmitted ultrasonic pulses are caused by tissue, blood flow, etc. inside the subject's body. When reflected, an echo signal resulting from this reflection is detected by the probe 101. After the echo signal detected by the probe 101 is converted into an electrical signal, it is sent to the phase detector 103 via the transceiver 102, and the Doppler shift signal is detected from the echo signal by the phase detector 103. It has become. The Doppler shift signal is converted into a digital signal by the A/D converter 104 and input to the MTI filter 105. The MTI filter 105 is a type of low-pass filter, and is capable of attenuating low-frequency clutter components of echo signals obtained from the tissue or blood vessel wall of the subject, and extracting only blood flow components. MTI filter 1
The blood flow components extracted by 05 are processed by blood flow information calculation means 1.
06 calculates speed, dispersion, power, etc., and the calculation results are displayed on the screen of the display 107.

0003

[Problem to be Solved by the Invention] However, in the conventional device, an IIR filter is used as the MTI filter 105, but because the number of data points is small, transient fluctuations occur in the output, making it impossible to obtain correct results. There is a point. Note that in order to display blood flow information two-dimensionally, it is necessary to move the acoustic scanning line, and in order to provide real-time display, it is necessary to obtain blood flow information for a single sample volume. The amount of data required for this purpose is reduced. For this reason, a method with a large number of data points is required.

[0004] In order to solve these problems, a method as described in Japanese Patent Application Laid-open No. 84532/1984 has been proposed. This is a method in which, assuming that the data to be input to the MTI filter are X1, X2, . . . Using this method, if the MTI filter is (X-
This is equivalent to inputting X1), (X2-X1), ... (Xn-Xn).

However, as shown in FIG. 5, this method has a problem in that the signal becomes discontinuous after the first data input, and transient signal fluctuations occur at this discontinuous portion. There is. In particular, this problem becomes noticeable when the clutter component is large relative to the blood flow signal.

The present invention solves the above-mentioned conventional problems, and aims to provide an ultrasonic Doppler imaging device that can prevent discontinuous information from being included in blood flow information. It is.

[0007]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a transmitting means for transmitting ultrasonic waves to a subject, a receiving means for receiving an echo signal reflected within the subject, and a receiving means for receiving an echo signal reflected within the subject. A detection means for detecting a Doppler shift signal from a received signal, a filter means for extracting a blood flow component from the detection output of the detection means, a display means for displaying the generated blood flow information, and a detection means for detecting clutter from the detection output of the detection means. A clutter information generating means for generating clutter information regarding a blood flow signal including a clutter component, a data calculating means for calculating data regarding a filter characteristic of the filter means from the generated clutter information, and a data calculating means. The ultrasonic Doppler imaging apparatus includes data setting means for setting the calculated data in the filter means as preset data.

[0008]

[Operation] Therefore, according to the present invention, clutter information is directly generated from the detection output of the detection means, data for correcting the filter characteristics of the filter information is calculated from the generated clutter information, and the calculated data is applied to the filter means. Since it is set as preset data, it is possible to prevent discontinuous information from being included in the blood flow information, and it is possible to prevent transient fluctuations from occurring in the output signal of the filter means.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing an embodiment of the present invention. In FIG. 1, the ultrasound Doppler imaging device includes a probe 1
, transceiver 2, phase detector 3, A/D converter 4, clutter information calculator 5, MTI filter data calculator 6, MT
It is composed of an I filter 7, a blood flow information calculator 8, and a display 9, and is provided with a clutter information calculator 5 as a clutter information generating means, and an MTI filter data calculator 6 as a data calculating means and a data setting means. It differs from that in FIG. 4 in some points.

When displaying blood flow information on the screen of the display 9, when an electrical pulse is generated from the transceiver 2, this pulse is converted into an ultrasonic pulse by the probe 1,
Ultrasonic pulses are transmitted into the subject. Then, an echo signal reflected from the subject is detected by the probe 1, this echo signal is converted into an electrical signal by the probe 1, and is input to the phase detector 3 via the transceiver 2. This echo signal is detected as a Doppler shift signal by a phase detector 3, and this Doppler shift signal is converted into a digital signal by an A/D converter 4. The output signal of the A/D converter 4 is input to the MTI filter 7 and also to the clutter information calculator 5.

The clutter information calculator 5 includes a rotation calculator 10, a phase calculator 11, and an amplitude calculator 12, as shown in FIG. Then, the clutter information calculator 5 receives the A/D converted I signals as X1, X2,...,
n and the Q signals are Y1, Y2, . . . , Yn, each part performs calculations to generate blood flow information. For example, the rotation angle calculation unit 10 performs the following (1) to (
3) The rotation angle is calculated according to the formula.

R1=(X1・Y1+X2・Y2)
(1) I1=(X2・Y1−X1・Y2)
(2) ω1=tan-1(I1/R1)
(3) At this time, ω2, ω3,..., ω
n may be determined and their average ωave may be determined and used in place of ω1 in the following operation. Also, this average (
It is also possible to average by weighting, such as ω1+0.5×ω2+0.3×ω2)/1.8.

On the other hand, the phase calculating section 11 calculates the phase according to the following equation (4).

Φ1=tan-1(Y1/X1)
(4) This phase is determined by the following (
5) Find Φn as shown in the formula.

Φn=tan-1(Yn/Xn)
(5) It is also possible to use equation (6).

Φ1ave=(Φ1+(Φ2−ω1)+……+(Φ
n-(ω1×(n-1))))/n

(6) It is also possible to apply weights to each of the above equations.

Further, the amplitude calculating section 12 calculates the amplitude according to equation (7).

A1=SQR(R12+I12) (7
) When calculating the amplitude, it is also possible to use an average, similar to rotation angle calculation and phase calculation.

Using the above equations, the clutter signal including blood flow can be approximated by the following equations (8) and (9).

Xn=Asin(ωt×(n-1)+Φ1) (
8) Yn=Acos(ωt×(n-1)+Φ1)
(9) Using the calculation method described above, the clutter signal containing blood flow was approximated to a sine wave signal, but as a filter using this approximation value, a second-order II filter as shown in FIG.
It is desirable to use an R filter. That is, as shown in FIG. 3, the MTI filter 7 includes an amplifier 21 and a delay device 22. With this configuration, the input/output relationship of the MTI filter 7 is expressed by the following equation (10).

OUTPUT(T)=A×INPUT(T)+B×
INPUT(T-1)+C×INPUT(T-2)+A
×D×OUTPUT(T-1)+A×E×OUTPUT
(T-2)
(10) From the above formula (10), INPUT(T), INPUT(T-1), INPUT
(T-2), OUTPUT (T-1), OUTPUT (
It is sufficient to provide each value of T-2) as preset data. Also, input data INPUT (T-1), I
NPUT(T-2) is obtained from equations (8) and (9). Furthermore, output data OUTPUT (T-1), OU
Since the amplitude input/output characteristic and the phase input/output characteristic with the frequency of this filter 7 as a parameter are known in advance, TPUT(T-2) is determined by referring to these characteristics and equation (10). After inputting the preset data obtained in this way to the MTI filter 7, the data R1, R2
, ..., Rn and I1, I2, ..., In, it is possible to suppress the occurrence of fluctuations in the output signal of the MTI filter 7.

[0022]

As is clear from the above embodiments, the present invention generates clutter information from the detection output of the detection means, calculates data for correcting the filter characteristics of the filter means from this clutter information, and filters the calculated data. Since the preset data is set in the filter means, it is possible to suppress the occurrence of transient fluctuations in the output signal of the filter means, and it is possible to display high-quality blood flow information.

[Brief explanation of drawings]

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

[Figure 2] Block diagram showing the clutter information calculator

[Figure 3]
Block diagram showing MTI filter

[Figure 4] Block diagram showing a conventional example

[Fig. 5] Explanatory diagram for explaining the characteristics of the conventional example

[Explanation of symbols]

1 Probe 2 Transmitter/receiver 3 Phase detector 4 A/D converter 5 Clutter information calculator 6 MTI filter data calculator 7 MTI filter 8 Blood flow information calculator 9 Display

Claims (1)

[Claims] 1. Transmitting means for transmitting ultrasonic waves to a subject; receiving means for receiving echo signals reflected within the subject; detection means for detecting a Doppler shift signal from a signal received by the receiving means; filter means for extracting blood flow components from the detection output of the detection means; display means for displaying the generated blood flow information; and blood flow signals containing clutter components from the detection output of the detection means. Clutter information generation means for generating clutter information, data calculation means for calculating data regarding filter characteristics of the filter means from the generated clutter information, and data setting means for setting calculated data of the data calculation means in the filter means as preset data. An ultrasound Doppler imaging device having