JP3356505B2 - Ultrasound Doppler 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 Doppler diagnosis for imaging a blood flow based on a specific moving object contained in a reception signal collected by repeating transmission and reception of an ultrasonic wave, in this case, a Doppler shift component caused by blood cells. Related to the device.

[0002]

2. Description of the Related Art In the pulse Doppler method, a transmission frequency is f0, a reception frequency is f1, a shift frequency is fd, a blood flow velocity is V, a sound velocity in a medium is C, and an angle between an ultrasonic beam and a blood flow is determined. When θ is set, the reception frequency f1 has a relationship as shown in Expression (1) with respect to the transmission frequency f0. Also, the shift frequency fd has a relationship with the blood flow velocity V as shown in equation (2).

F 1 = {(1 + V · cos θ / C) / (1−V · cos θ / C)} · f 0 to (1 + 2 V · cos θ / C) · f 0 (1) where “〜” means near-like call I do.

Fd = f1−f0 = (2V · cosθ / C) · f0 (2) Therefore, the blood flow velocity is obtained by measuring the velocity component (Vcosθ) in the ultrasonic beam direction based on the shift frequency fd. Is done. This velocity component is corrected to the actual blood flow velocity by the angle θ.

A conventional ultrasonic Doppler diagnostic apparatus will be described with reference to FIG. From the transmission / reception system 12 to the ultrasonic probe 11
A drive pulse is supplied to each of the vibrators at a constant repetition cycle (rate frequency). Thereby, the ultrasonic probe 11
, Ultrasonic pulses are repeatedly transmitted in the same direction in the living body. The reflected wave reflected in the living body is received by the ultrasonic probe 11 and converted into an electric signal. The ultrasonic transmission / reception is repeated while sequentially moving in the direction as shown in FIG. The received signal thus obtained is sent to the detector 18 via the transmission / reception system 12. In the detector 18,
The received signal is subjected to envelope detection, and is then subjected to a digital scan converter (DSC) 34 and a multiplexer (MP).
X) 37 and a digital-to-analog converter (D / A) 38 are displayed in order on the display means 39 as a B-mode image. On the other hand, the received signal is also sent to mixers 24a and 24b. The received signals are received by mixers 24a and 24b, respectively.
It is multiplied by a reference signal having a phase difference of 0 °. Mixer 2
4a and 24b are output from low-pass filters 26a and 26a.
26b, where the high frequency components are removed. The output signals of the low-pass filters 26a and 26b are sent to a color flow mapping (CFM) processing system 27, and first, the A / A
The signals are converted into digital signals by the D converters 28a and 28b. Thereafter, clutter components such as side lobes are removed by MTI (Moving-Target-Indicator) filters 29a and 29b.

The output signals of the MTI filters 29a and 29b are frequency-analyzed in real time by a fast Fourier transformer (FFT) 30. As a result, a Doppler shift frequency that depends only on the blood cell movement is detected. Various calculation units 3
In steps 1 to 33, the average velocity, variance, and power are calculated based on the Doppler shift frequency. The result of this calculation is passed through the digital scan converter 35 and the color information conversion unit 36 in this order, and the multiplexer (M
PX) 37. In the multiplexer 37, these average speed, dispersion and power are appropriately combined and synthesized into a B-mode image, and the digital-analog converter (D / D
A) It is displayed on the display unit 39 via 38. However, it is very difficult to find an abnormal blood flow such as a turbulent flow or a short-circuited blood flow using only the average velocity, dispersion, and power.

[0007]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an ultrasonic Doppler diagnostic apparatus which assists in finding abnormal blood flow such as turbulence or short-circuit blood flow in order to cope with the above circumstances. And

[0008]

According to a first aspect of the present invention.
Ultrasound Doppler diagnostic equipment scans an object with an ultrasonic beam.
Means for collecting a received signal by examining the received signal.
The Doppler shift frequency component of a given moving object contained in the signal
Means for extracting, and a frequency component of the Doppler shift frequency component
The degree of bias in the high frequency range or the low frequency range
Means for calculating index information that quantifies the degree of bias
And means for displaying the index information.
It is characterized by the following. Ultrasonic dope according to a second aspect of the present invention
LA diagnostic equipment scans the inside of the subject with an ultrasonic beam
Means for collecting a received signal according to:
Based on the Doppler shift frequency component of a given mobile object
Means for measuring the average speed of several locations, and a predetermined number of neighboring locations
Between the index speed and the average speed variation between
And means for calculating and displaying the index information
Means.

[0009]

According to the first aspect of the present invention, the Doppler shift frequency
The degree of deviation of the frequency distribution of the component toward the high frequency range or
The characteristic of the shape of the frequency distribution depends on the degree of bias toward the low frequency range.
Abnormalities such as turbulence and short-circuit blood flow
Can easily recognize the presence of blood flow and its abnormal state
You. According to a second aspect of the invention, an average speed between neighboring locations
Understanding the local turbulence of blood flow to some extent from the degree of variation
Abnormal blood flow, such as turbulence or short-circuit blood flow,
Abnormal state can be easily recognized.

[0010]

An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of the first embodiment. The probe 11 has a plurality of piezoelectric vibrators arranged one-dimensionally.
The transmitting and receiving circuit 12 is connected to the probe 11. In the transmission / reception circuit 12, the delay line 16 is connected to the oscillator 1 in order to focus ultrasonic waves from each transducer in a predetermined direction.
A specific delay time is given to each oscillator with respect to the rate pulse from 4 and output to the pulser 14. The pulser 14 supplies a drive pulse to each transducer of the probe 11 according to a pulse output from the delay line 16. An ultrasonic pulse is transmitted from the probe 11 into the living body by the driving pulse. The ultrasonic pulse is reflected at the boundary of the acoustic impedance in the living body. This reflected wave is received by each transducer of the probe 11. The received signal received by each transducer is added to the adder 1 via the preamplifier 13 and the delay line 16 in this order.
7 where it is added. This addition signal is sent to the detector 18. After logarithmically amplifying the added signal, the detector 18 detects the envelope. Thereby, a tomographic image (B-mode image) is created.

The addition signal output from the adder 17 is supplied to mixers 24a and 24b. The rate pulse from the oscillator 14 is supplied to one mixer 24a as it is, and is multiplied by the addition signal. The other mixer 24
b is a 90 ° phase shifter 2 with a rate pulse from the oscillator 14.
5 and is multiplied by the sum signal. Output signals from the mixers 24a and 24b are supplied to a color flow mapping (CFM) system 27 via separate low-pass filters 26a and 26b. Low-pass filter 26
a and 26b remove high frequency components (frequency components corresponding to twice the transmission frequency) included in the output signals from the mixers 24a and 24b from the output signals.

In the color flow mapping system 27,
Output signals of the low-pass filters 26a and 26b are supplied to MTI filters 29a and 29b via analog-to-digital converters (A / D) 28a and 28b. MTI is an abbreviation of Moving-Target-Indicator, a technique commonly used in radar, and a method of detecting only a specific moving target using the Doppler effect. MTI filter 2
9a and 29b remove clutter components from the output signals of the low-pass filters 26a and 26b. The clutter component is an unnecessary reflection component from a slowly moving object such as a heart wall.

The output signals of the MTI filters 29a and 29b are subjected to frequency analysis by a fast Fourier transformer (FFT) 30. Thus, the Doppler shift frequency due to the blood flow is measured. The frequency analysis result is sent to the average speed calculator 31, the variance calculator 32, and the power calculator 33. The average speed calculator 31, the variance calculator 32, and the power calculator 33 calculate the average speed, variance, and power for each sample volume in the ultrasonic field of view based on the Doppler shift frequency.

The frequency analysis result is also supplied to an index calculator 40. The index calculation unit 40
Index information is calculated for each sample volume based on the frequency analysis result by the fast Fourier transformer 30. The Doppler spectrum in which the frequency analysis result in the same sample volume is distributed in an orthogonal region including the power (signal strength) axis and the frequency axis corresponds to the distribution of the blood flow velocity at each point in the sample volume. Therefore, the presence of an abnormal blood flow component such as a turbulent flow or a short-circuited blood flow can be determined from the characteristics of the waveform of the Doppler spectrum. The value of the index information is reflected on the characteristic of the waveform of the Doppler spectrum. In the present embodiment, the characteristic of the waveform of the Doppler spectrum is the degree of bias of the Doppler spectrum toward a high frequency range,
Alternatively, the degree of bias toward a low frequency range is quantified. The method of calculating the index information will be described later.

The index information is stored in a digital scan converter (DS) as well as the average speed, variance, and power.
C) It is sent to 35. The index information is output from the digital scan converter 35 to the color information conversion unit 36. The color information conversion unit 36
The index information from the digital scan converter 35 is converted into color information according to an appropriate color bar, and output to a multiplexer (MPX) 37. The multiplexer 37 converts the B-mode image created by the detector 18 into a digital scan converter (DSC) 3.
4. The B-mode image is combined with index information by a multiplexer 37 and is displayed via a digital / analog converter (D / A) 38 on a display unit 39.
Will be displayed.

Next, the operation of this embodiment will be described. When the probe 11 is driven by the transmission / reception circuit 12, the ultrasonic pulse is transmitted into the living body at a constant repetition frequency (rate frequency). The reflected wave reflected in the living body is received by the probe 11. This received signal is sent to the detector 18 and the mixers 24a and 24b via the transmission / reception circuit 12. The received signal sent to the detector 18 has its envelope detected. The detection result is sent to the multiplexer 37 via the digital scan converter 34 as a B-mode image.

On the other hand, the received signals sent to the mixers 24a and 24b are multiplied by rate pulses different in phase by 90 °, and then high-frequency components are removed by low-pass filters 26a and 26b. Output signals from the low-pass filters 26a and 26b are supplied to MTI filters 29a and 29b via analog-to-digital converters 28a and 28b of the color flow mapping processing system 27, where clutter signals are removed. The output signals of the MTI filters 29a and 29b are subjected to frequency analysis by the fast Fourier transformer 30. As a result, a frequency component that depends only on the blood flow, that is, a Doppler shift frequency, is extracted from the output signals of the MTI filters 29a and 29b. The Doppler shift frequency is sent to the operation units 31 to 33 and the index calculation unit 4
Sent to 0.

FIG. 2 is a diagram showing a Doppler spectrum of a certain sample volume. As described above, the index calculating unit 40 individually calculates index information indicating the characteristics of the waveform of the Doppler spectrum for all sample volumes in the ultrasonic field. Index information fw
Is calculated according to the following equation (3) using the maximum frequency fmax of the Doppler spectrum and the power peak frequency fpeak having the highest power.

Fw = fmax-fpeak (3) As a result, the index information fw shows a low value when the Doppler spectrum is biased toward a high frequency region as shown in FIG. 3 (a), and FIG. 3 (b) As shown in (1), when the frequency is biased to the low frequency range, the value becomes high. This calculation is performed for all sample volumes, and the index information fw is stored in the digital scan converter 3.
The color information conversion unit 36 converts the color information into color information in which, for example, the higher the value, the stronger the red density and the lower the value, the higher the blue density. Thus, a two-dimensional distribution (index image) of the index information fw is created. This index image is stored in the multiplexer 3
At 7, the image is synthesized with the B-mode image. This composite image is displayed on the display unit 39 via the digital-to-analog converter 38.

As described above, according to this embodiment, each sample volume is displayed two-dimensionally in a color corresponding to the characteristic of the waveform of the Doppler spectrum of each sample volume. Since the characteristics of the waveform of the Doppler spectrum correspond to the velocity distribution of the blood flow, this velocity distribution can be understood in detail by the color difference. Therefore, the ultrasonic Doppler diagnostic apparatus according to the present embodiment can assist in finding an abnormal blood flow such as a turbulent flow or a short-circuit blood flow.

Note that the index information fw may be obtained by another calculation method as long as the characteristic of the waveform of the Doppler spectrum is represented. For example, the following formulas (4) and (5) are exemplified as the calculation formulas.

Fw = fmax / fpeak (4) fw = (fmax-fpeak) / fpeak (5) Next, a second embodiment will be described. The configuration of the ultrasonic Doppler diagnostic apparatus according to the present embodiment is the same as that of FIG. The difference is the calculation method of the index calculation unit 40.

In the calculation method according to the present embodiment, first, the integrated value (area equivalent) of each of the plus side and the minus side is calculated around the frequency 0 of the Doppler spectrum. The index fw is calculated according to the shape of the spectrum distribution. This integration calculation is performed on finite points on the frequency axis as shown in Table 1 below in order to reduce the amount of calculation processing. Note that fr is the frequency of the rate pulse, that is, the rate frequency.

[0024]

[Table 1]

The power P1 at n points from the Doppler spectrum
.About.Pn are extracted. The powers P1 to Pn at the n points
Is applied to the following equations (6), (7), (8), and (9).

[0026]

(Equation 1)

Thus, the total power Pto, the plus power Ppl, the minus power Pmi, and the average power Pave are calculated. The total power Pto is the integrated power value of the entire frequency range, the plus power Ppl is the integrated power value of the plus range shown by the slanted line in FIG. 4 (a), and the minus power Pmi is shown by the slanted upper right line in FIG. 4 (a). The power integrated value and average power Pave in the minus range are power average values in all frequency ranges. In FIG. 4A, Pnoi is a noise level, and this numerical value is given in advance.

These Pto, Ppl, Pmi, Pave, Pnoi
Is applied alternatively to the following equations (10) to (15). fw = Pmi / Ppl (10) fw = Pmi / Pto (11) fw = {Pmi-Pave. (n / 2)} / {Ppl-Pave. (n / 2)} (12) fw = { Pmi−Pave · (n / 2)} / {Pto−Pave · (n / 2)} (13) fw = {Pmi−Pnoi · (n / 2)} / {Ppl−Pnoi · (n / 2) } (14) fw = {Pmi−Pnoi · (n / 2)} / {Pto−Pnoi · (n / 2)} (15) Calculated by equations (10) to (15). The index information has unique properties. Selection of Expressions (10) to (15) is left to the operator. The operator selects these expressions appropriately and applies them to the calculation of the index information.

The index information fw obtained by any of the above expressions changes according to the characteristics of the shape of the Doppler spectrum. That is, similarly to the first embodiment, when the Doppler spectrum is biased toward the high frequency range, the value is low, and when the Doppler spectrum is biased toward the low frequency range, the value is high. Therefore, according to this embodiment, the same effect as that of the first embodiment can be obtained.

Note that Pave and Pnoi in the above equations (12) to (15) may be multiplied by an arbitrary constant. In this case, when the constant is appropriately set, the index information f
The height difference of w becomes large, and the feature of the shape of the Doppler spectrum is more remarkably expressed. Also, the above-mentioned Pto, Pp
l and Pmi are expressed by the following equations (16) and (1), respectively.
7), and may be obtained by equation (18).

[0031]

(Equation 2)

Note that PP is either Pave or Pnoi,
P (n) ≧ PP indicates that only P (n) greater than or equal to PP is extracted. FIG. 4B is a diagram showing Ppl and Pmi when Pave is selected as PP. This equation (1
6), Pto, Ppl, and Pmi obtained by Expressions (17) and (18) are applied to any of Expressions (10) to (15), and index information fw is calculated.

Next, a third embodiment will be described. The configuration of the ultrasonic Doppler diagnostic apparatus according to the present embodiment is the same as that of FIG. The difference is the calculation method of the index calculation unit 40. In the present embodiment, the index information fw is calculated using the power integrated values on the plus side and the minus side centered on the frequency 0 in the second embodiment, whereas the average information is calculated centered on the average frequency fave. The index information fw is calculated from the power integrated value in the frequency range exceeding the frequency fave and the power integrated value in the frequency range equal to or lower than the average frequency fave.

In this embodiment, similarly to the second embodiment, the integrated value is calculated using the power at the finite point in order to reduce the amount of calculation processing. That is, powers P1 to Pn at n points on the frequency axis are sampled.

The powers P1 to Pn at the n points are applied to the following equations (19), (20) and (21).
The total power Pto, the plus power Ppl, and the minus power Pmi are calculated. K is the data number of the average frequency fave in Table 1. In the present embodiment, the total power Pto is the integrated value in the plus region, the plus power Ppl is the integrated value in the frequency region exceeding the average frequency fave indicated by the slanted line in FIG.
mi is the average frequency fave shown in FIG.
These are integrated values in the following frequency ranges.

[0036]

(Equation 3)

The Pto, Ppl, Pmi, Pave and Pno
i is alternatively applied to the following equations (22) to (27), and index information fw is obtained. fw = Pmi / Ppl (22) fw = Pmi / Pto (23) fw = {Pmi−Pave · (n / 2−K + 1)} / {Ppl−Pave · (n / 2−K + 1) } ... (24) fw = {Pmi-Pave. (N / 2-K + 1)} / {Pto-Pave. (N / 2-K + 1)} ... (25) fw = {Pmi-Pnoi. ( n / 2−K + 1)} / {Ppl−Pnoi · (n / 2−K + 1)} (26) fw = {Pmi−Pnoi · (n / 2−K + 1)} / {Pto− Pnoi · (n / 2−K + 1)} (27) The index information calculated by each of the equations (22) to (27) has a unique property. Selection of Expressions (22) to (27) is left to the operator. The operator selects these expressions appropriately and applies them to the calculation of the index information.

The index information fw obtained by any of the above equations changes according to the characteristics of the shape of the Doppler spectrum. That is, when the plus component of the Doppler spectrum is biased toward the higher frequency range than the average frequency, the value is low, and when the plus component is biased toward the lower frequency range, the value is high. Therefore, according to the present embodiment, it is possible to determine the state of the hemorrhagic flow in more detail.

In this embodiment, Pave and Pnoi may be multiplied by a predetermined constant, and the positive power Ppl and the negative power Pmi may be calculated based on the peak frequency Ppeak used in the first embodiment instead of the average frequency. You may make it. Further, Ppl and Pmi are expressed by the following equations (28) and (29).
May be calculated by PP is Pave
And Pnoi, and P (n) ≧ PP means that only P (n) greater than or equal to PP is extracted. FIG. 5B shows Ppl when Pave is selected as PP.
FIG. 3 is a diagram showing (downward right oblique lines) and Pmi (upper right oblique lines).

[0040]

(Equation 4)

The values of P obtained by the equations (28) and (29)
The index information fw is calculated by applying pl and Pmi to any of the above equations (22) to (27). Next, a fourth embodiment will be described.

FIG. 6 is a block diagram showing the configuration of the ultrasonic Doppler diagnostic apparatus according to this embodiment. The same parts as those in FIG. 1 are denoted by the same reference numerals as those in FIG. This embodiment is different from the first embodiment in that the index calculation unit 4
This is the calculation method of 1.

In the first embodiment, the index information fw is calculated from the maximum frequency fmax of the Doppler spectrum and the frequency fpeak having the highest power. In this embodiment, the index information is calculated from the maximum frequency fmax of the spectrum and the average frequency fmean. The information fm is calculated.

FIG. 7 shows the Doppler spectrum of a certain sample volume as in FIG. Index calculator 4
In 1, the highest frequency fmax of the Doppler spectrum
, Average frequency fmean is determined. The maximum frequency fmax and the average frequency fmean are applied to the following equation (30), whereby the index fm is calculated.

Fm = fmax−fmean (30) Therefore, as shown in FIG. 8A, the index information fm indicates a low value when the waveform of the Doppler spectrum is biased toward the high frequency region around the average frequency fmean. As shown in FIG. 8B, when the waveform of the Doppler spectrum is biased toward a low frequency region around the average frequency fmean, the waveform has a high value.

As described above, according to this embodiment, the same effects as those of the first embodiment can be obtained. Note that the index information fm is not limited to Expression (30), and as long as the characteristics of the waveform of the Doppler spectrum are expressed numerically, for example, the following Expression (3)
It may be calculated by 1) or equation (32).

Fm = fmax / fmean (31) fm = (fmax-fmean) / fmean (32) Next, a fifth embodiment will be described.

In this embodiment, the above-described first to fourth embodiments are applied to a so-called one-point Doppler method. FIG. 9 is a block diagram of the present embodiment. FIG.
The same parts as those in FIG.

The spectrum Doppler operation unit 70 converts a signal corresponding to a specific sample blue from the output signals of the low-pass filters 26 a and 26 b into a sample hold unit 7.
Extract by 1a and 71b. Output signals of the sample hold units 71a and 71b are supplied to a high-pass filter 72.
a, 72b, low-pass filters 73a, 73b, amplifiers 74a, 74b, analog digital converter (A / D)
High-speed Fourier converter (FF)
T) 76. The high-speed Fourier transformer 76 continuously calculates the Doppler shift frequency of each point in the sample volume over time by subjecting the input signal to a high-speed Fourier transform process, and calculates the Doppler shift frequency of these points. The Doppler spectrum is continuously output to the index calculator 40. The index calculation unit 40 obtains the maximum frequency Pmax and the power peak frequency Ppeak of the Doppler spectrum at a specific time specified by the operation of an input device (not shown) by the operator, and converts the index information fw using the above equation (3). calculate. The index information fw is numerically displayed on the display unit 39 via the digital-to-analog converter 38 together with the B-mode image 81 and the time variation graph 82 of the shift frequency as shown in FIG. In FIG. 10, reference numeral 80 denotes a cursor indicating the position of the sample volume, and reference numeral 83 denotes a cursor indicating the specific time. FIG. 11 is an enlarged view of the time variation graph 82 of FIG.

The index information fw calculated in this manner has a waveform of a Doppler spectrum having a power peak frequency fpe as shown in FIG.
When the frequency of the Doppler spectrum is biased toward the low frequency range around the power peak frequency fpeak as shown in FIG. .

The calculation of the index information as described above can be easily applied to a so-called one-point Doppler device. In the above description, the case where the calculation method of the index information is that of the first embodiment has been described. Of course, the calculation methods of the second to fourth embodiments may be adopted.

Next, a sixth embodiment will be described. FIG. 13 is a block diagram of the present embodiment. The same parts as in FIG.
The same reference numerals are given and the description is omitted.

In this embodiment, an autocorrelator 43 capable of executing frequency analysis at multiple points in the ultrasonic field of view in real time is used as a frequency analyzer. The index calculator 44 receives the average speed and the variance from the average speed calculator 31 and the variance calculator 32, and calculates the index information tσ using the average speed and the variance. This index information tσ is
It is supplied to a digital scan converter 35.
A method of calculating the index information tσ by the index calculating unit 44 will be described below.

The average speed v from the average speed calculator 31 and the variance σ 2 from the variance calculator 32 are calculated by the following equation (3)
3), Equation (34), Equation (35), or Equation (36). As a result, index information tσ having a property unique to each equation is calculated.

Tσ = σ ² + v ² (33) tσ = (σ ² + v ² ) ^1/2 (34) tσ = (σ ² + v ² ) / v ² (35) tσ = ((σ ² + v) ² ) / v ² ) ^1/2 (36) As easily understood from the calculation formula, the formula (35),
Equation (36) is an equation obtained by normalizing Equations (33) and (34) with the average speed v. Incidentally, the average speed v is calculated according to the following equation (37), and the variance σ2
Is calculated according to equation (38).

[0056]

(Equation 5)

As can be seen from Equations (37) and (38), the variance σ2 indicates the degree of spread of the Doppler spectrum centered on the average velocity v, while the index information tσ is obtained by the above equation (33). )-(36), the variance .sigma.2 is changed according to the square value of the average speed v. That is, even if the variance .sigma.2 has the same Doppler spectrum, the index information t.sigma. Has a different value if the average speed v is different.

More specifically, even when the Doppler spectrum is biased toward a high frequency range as shown in FIG. 14A, the variance σ 2 is reduced to a low frequency range as shown in FIG. Even if the component is biased, the same value is shown if the spread width is the same. On the other hand, the index information tσ of the present embodiment indicates a high value when the waveform of the Doppler spectrum is as shown in FIG. 14A, and indicates a low value when the waveform of FIG. 14B is.

As described above, the calculation of the index information tσ can be easily performed not only by using the result of the frequency analysis, but also by using the calculation results of the average speed calculation unit 31 and the dispersion calculation unit 32. In this embodiment, in the above equations (35) and (36), σ ² + v ² may be simply set to σ ² . Of course, as shown in FIG. 15, the index calculator 44 may be directly connected to the autocorrelator 43, and the index information tσ may be calculated using the output signal of the autocorrelator 43. In this case, the formulas (33) to (36) are substituted for the formulas (37) and (38) in the calculation formula of the index information tσ, and the following formulas (39), (40), (41) and equation (42).

[0060]

(Equation 6)

Next, a seventh embodiment will be described. FIG. 16 is a block diagram of the present embodiment, and FIG.
3, the detailed description is omitted.

The index calculator 45 calculates the index information σa using the average speed v output from the average speed calculator 31. Here, the coordinates of the sample volume in the ultrasonic field are indicated by (i, j). Note that 1 ≦ i ≦
r (r: the number of scanning lines) and 1 ≦ j ≦ d (d: the number of sample volumes in the depth direction). The average velocity of each sample volume is indicated by v (i, j). Hereinafter, a method for calculating the index information σa according to the present embodiment will be described below.

The average speed v of each sample volume is continuously supplied to the index calculator 45 from the average speed calculator 31 in the order of operation. The index calculation unit 45 calculates, for example, for every 3 × 3 localities in the same field of view, that is, for every nine neighboring sample volumes, the degree of variation, for example, the variance of the average velocity v of each sample volume included in the locality. This calculation result is obtained by adding index information σ to the center coordinates (i, j) of the local area.
a (i, j). Specifically, as shown in FIG. 17, an average value V (i, j) of a certain center coordinate (i, j) and eight points around the center coordinate is calculated by the following equation (43).

[0064]

(Equation 7)

Applying this V (i, j) to equation (44), the variance, that is, the local index information σa
Calculate (i, j). The index calculator 45 calculates index information σa (1,1) to σa (r, d) centering on all sample volume points while shifting the center coordinates by one sample volume in order. These index information σa (1,1) to σa (r,
d) is the index information 2 via the digital scan converter 35 and the color information conversion unit 36.
It is displayed in color as a dimensional distribution. Of course, at least one point of index information σa specified by the operator may be numerically displayed.

According to this embodiment, the degree of dispersion of the average velocity between a plurality of neighboring sample volumes is displayed as image information, so that a spatial change in blood flow velocity can be easily grasped.

In this embodiment, the index information σ
Although the local size for calculating a is set to 9 points, the present invention is not limited to this. Further, although the index information σa in the present embodiment is a variance value of the average velocity in the local area, the present invention is not limited to this, and may be, for example, a standard deviation or a difference between the maximum value and the minimum value. Further, since the calculated index information σa is a variance value within a predetermined range (a range corresponding to a local range), it is necessary to estimate the size of an abnormality (stenosis) based on the variance value, the blood vessel diameter, and the center average velocity. Can be. In this case, for example, a message that “a stenosis of 3 mm exists 2 cm upstream” is displayed.

Next, an eighth embodiment will be described. FIG. 18 is a block diagram of the present embodiment. The same parts as those in FIG. 13 are denoted by the same reference numerals as those in FIG.

In general, abnormalities such as stenosis are most reflected in the blood flow state during the diastole of the heart. The present embodiment is characterized in that the index information σa is calculated based on a received signal measured in a specific time phase, that is, a diastole of the heart.

To this end, a time phase indicating unit 50 is connected to the index calculating unit 44. The time phase instructing unit 50 instructs the index calculating unit 44 of a timing (time phase) for calculating the index information σa. An electrocardiograph 51 is connected to the phase indicator 50. The electrocardiograph 51 measures the electrocardiogram of the subject, and supplies the electrocardiogram to the time phase indicator 50. Time phase indicator 5
0 indicates an arbitrary phase set by operating the input device 52, for example, a diastole of the heart, based on the P wave of the waveform of the electrocardiogram, and triggers the index calculator 44 during the diastole. Output a signal. FIG. 19 is a diagram showing the time variation of the Doppler spectrum for a certain sample volume. In FIG. 19, the period during which the trigger signal is output is a period indicated by a.

The index calculator 44 uses the average speed v input from the average speed calculator 31 and the variance σ2 input from the variance calculator 32 during the input period of the trigger signal and calculates the index according to the following equation (45). Information σa
Is calculated. C1 is an arbitrary coefficient.

Σa = (σ ² / v ² ) × C 1 (45) The index information σa indicates a high value when the Doppler spectrum is biased toward the high frequency side, as shown in FIG. As shown in (b), when the frequency is biased toward the low frequency side, a low value is indicated.

According to the present embodiment, it is possible to calculate and display the index information σa of a specific time phase in which abnormalities such as stenosis are easily reflected, that is, the diastolic phase of the heart. Therefore, it is easy to grasp the abnormal blood flow. Of course, the time phase for calculating the index information σa is not limited to the diastole but may be any time phase. In this case, this time phase is set by operating the input device 52. In this embodiment,
An electrocardiograph 51 is provided to recognize the time phase for calculating the index information σa based on the electrocardiogram measured by the electrocardiograph 51, but the movement of the heart is the time of the average speed v of the average speed calculation unit 31. Index information σa
May be recognized based on the temporal variation of the average speed v.

Next, a ninth embodiment will be described. FIG. 21 is a block diagram of the present embodiment. 9 and 18 are denoted by the same reference numerals as in FIGS. 9 and 18, and description thereof is omitted.

As in the eighth embodiment, the present embodiment is characterized in that the index information fw is calculated based on a reception signal measured at a specific time phase, that is, during the diastole of the heart.
For this reason, the time phase indicating unit 50 is connected to the index calculating unit 40. The time phase instructing section 50 outputs the index information fw.
Is calculated by the index calculator 4
Indicate 0. An electrocardiograph 51 is connected to the phase indicator 50. The electrocardiograph 51 measures the electrocardiogram of the subject, and supplies the electrocardiogram to the time phase indicator 50. The time phase indicating section 50 may be an arbitrary time phase set with an arbitrary time width by operating the input device 52 based on, for example, the P wave of the waveform of the electrocardiogram, or a previously fixed time phase, here, the expansion of the heart. Recognize the period, and output a trigger signal to the index calculation unit 40 during the expansion period. FIG. 22 is a diagram showing a signal supplied from the fast Fourier transformer 76 to the index calculator 40 along a time axis. In FIG. 22, the period during which the trigger signal is output is a period indicated by a or b.

The index calculator 40 calculates index information fw using the Doppler spectrum of the output signal from the fast Fourier transformer 76 during the input period of the trigger signal. The index calculator 40 calculates the maximum frequency Pmax and the power peak frequency Ppeak of the Doppler spectrum based on the received signal detected during the diastole of the heart, as in the fifth embodiment, and obtains the index information fw according to equation (3). May be calculated, or the mixing ratio of the backflow component may be calculated as the index information fw using the integrated value (area value) of the backflow component or the forward flow component according to the following equation (46). FIG. 23 shows the Doppler spectrum. The backflow component A is a minus component in a portion exceeding a value obtained by multiplying the average power indicated by oblique lines in FIG. 23 by the coefficient α. The forward flow component B is a plus component in a portion exceeding a value obtained by multiplying the average power indicated by oblique lines in FIG. 23 by a coefficient α.

Fw = A / (A + B) (46) It should be noted that only the portion exceeding the value obtained by multiplying the average power by the coefficient α is to be calculated. Is likely to contain a noise component. The frequency range for calculating the index information fw may be the entire frequency range or a specific frequency range. However, ideally, in order to mitigate the effect of the so-called aliasing phenomenon in which the polarity of the frequency component exceeding the dynamic range in the frequency range of the entire device is reversed, the frequency range is set near the frequency 0. desirable.

The index information fw of the diastolic phase of the heart calculated in this way is numerically displayed on the display unit 39 via the digital / analog converter 38. As described above, according to the present embodiment, the same effects as those of the eighth embodiment can be obtained. The averaging process of each frequency component in the time axis direction and / or the frequency axis direction may be performed as a pre-process of the index information fw calculation process. In this case, since the error component is reduced, the stability of the calculation result is improved.

The present invention is not limited to the above-described embodiment, but can be implemented with various modifications without departing from the scope of the invention. For example, the index obtained in the above embodiment is
For example, a portion having a high index level may be highlighted by using it as, for example, a luminance modulation signal of each pixel of the blood flow imaging image. Further, instead of displaying one index corresponding to one pixel, an average value obtained by averaging a predetermined number of indices within a spatial or temporal range may be displayed. After averaging data of predetermined pixels in a typical range, an index may be obtained and displayed. Further, a plurality of the above embodiments may coexist in one ultrasonic Doppler diagnostic apparatus, any one of which may be selectively operated, and the type of index to be displayed may be switched by a switch.

[0080]

According to the first aspect of the present invention, Doppler shift
The deviation of the frequency distribution of the frequency component toward the high frequency range
Degree or degree of deviation to low frequency range, the shape of frequency distribution
Turbulence, short-circuit blood flow, etc.
To easily recognize the presence of abnormal blood flow and abnormal conditions
Can be. According to a second aspect of the present invention,
From the variation of the average velocity, the more the local blood flow is disordered
The presence of abnormal blood flow, such as turbulence and short-circuit blood flow.
The presence or abnormal state can be easily recognized.

[Brief description of the drawings]

FIG. 1 is a block diagram of a first embodiment.

FIG. 2 is a diagram showing a Doppler spectrum input to an index calculator shown in FIG. 1;

FIG. 3 is a diagram showing two types of Doppler spectrum.

FIG. 4 is a diagram showing a Doppler spectrum for explaining an index calculation method according to a second embodiment.

FIG. 5 is a diagram showing a Doppler spectrum for explaining an index calculation method according to a third embodiment.

FIG. 6 is a block diagram of a fourth embodiment.

FIG. 7 is a diagram showing a Doppler spectrum input to the index calculator of FIG. 6;

FIG. 8 is a diagram showing two types of Doppler spectra.

FIG. 9 is a block diagram of a fifth embodiment.

FIG. 10 is a diagram showing a display screen of the display unit in FIG. 9;

11 is an enlarged view of the time variation graph of FIG.

FIG. 12 is a diagram showing two types of Doppler spectra.

FIG. 13 is a block diagram of a sixth embodiment.

FIG. 14 is a diagram showing two types of Doppler spectra.

FIG. 15 is a modification of the sixth embodiment.

FIG. 16 is a block diagram of a seventh embodiment.

FIG. 17 is a diagram showing a local range of local processing.

FIG. 18 is a block diagram of an eighth embodiment.

FIG. 19 is a diagram showing an example of a time phase for performing index calculation indicated by the index calculation time phase indicator of FIG. 18;

FIG. 20 is a diagram showing two types of Doppler spectra.

FIG. 21 is a block diagram of a ninth embodiment.

FIG. 22 is a view showing an example of a time phase set by the time phase indicator of FIG. 21;

FIG. 23 is a diagram showing a Doppler spectrum of a time phase set by the time phase indicator.

FIG. 24 is a block diagram of a conventional ultrasonic Doppler diagnostic apparatus.

FIG. 25 is a view showing a scanning procedure of a sector scan.

[Explanation of symbols]

11 Probe, 12 Transmitter / receiver circuit, 24a, 24b ...
Mixer, 25: 90 ° phase shifter, 26a, 26b: low-pass filter, 27: color flow mapping processing system, 3
4, 35 ... digital scan converter, 36 ...
Color information change unit, 37 ... multiplexer, 38
... Digital-to-analog converter, 39 ... Display unit, 4
0: Index calculator

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kazuaki Yasuhara 4-2-5, Chigusa Taipei, Wakaba-ku, Chiba City, Chiba Prefecture (72) Inventor Yasuo Miyajima 1385-1 Shimoishigami, Otawara-shi, Tochigi 1 (56) References JP-A-3-133438 (JP, A) JP-A-2-264644 (JP, A) JP-A-2-271840 (JP, A) JP-A-4-183454 (JP, A) ( 58) Field surveyed (Int. Cl. ⁷ , DB name) A61B 8/00-8/15

Claims (9)

(57) [Claims] A means for collecting a reception signal by scanning an inside of a subject with an ultrasonic beam; a means for extracting a Doppler shift frequency component of a predetermined moving object included in the reception signal; High frequency for the frequency distribution of the shifted frequency component
Quantify the degree of deviation to several ranges or the degree to low frequencies
An ultrasonic Doppler diagnostic apparatus, comprising: means for calculating the calculated index information; and means for displaying the index information. 2. The method according to claim 1, wherein the calculating unit calculates a highest frequency of the frequency distribution.
The ultrasonic Doppler diagnostic apparatus according to claim 1, wherein the index information is calculated based on a wave number and a power peak frequency having the highest power . 3. The calculation means according to claim 1 , wherein
The ultrasonic Doppler diagnostic apparatus according to claim 2, wherein the index information is calculated based on a difference from a low peak frequency . 4. The calculation means according to claim 1, wherein
Calculate the ratio of the negative component as the index information
2. The ultrasonic Doppler diagnosis according to claim 1, wherein
apparatus. 5. The calculation means according to claim 1, wherein
Power integrated value in all frequency ranges or power integrated value in positive range
The ratio of the power integrated value in the negative range to
5. The calculation according to claim 4, wherein the calculation is performed as information on
Ultrasonic Doppler diagnostic device. 6. The apparatus according to claim 1, wherein said calculating means calculates a two-dimensional distribution of said index information within a scanning range, and said display means displays said two-dimensional distribution as an image. Item 7. An ultrasonic Doppler diagnostic apparatus according to Item 1. 7. The ultrasonic Doppler diagnostic apparatus according to claim 6, wherein said display means displays said two-dimensional distribution as a color image in accordance with a value of said index information. 8. A means for collecting a reception signal by scanning the inside of a subject with an ultrasonic beam; An ultrasonic Doppler diagnostic apparatus comprising: means for measuring; means for calculating the degree of variation in the average speed between a predetermined number of neighboring positions as index information; and means for displaying the index information. 9. The ultrasonic Doppler diagnostic apparatus according to claim 1, wherein said calculating means calculates index information based on a reception signal collected at a specific time phase.