JPH0556973A - Ultrasonic blood flow imaging device - Google Patents

Abstract

PURPOSE:To allow even the intricately running blood vessels to be efficiently and exactly diagnosed by properly controlling respective parameters to a scanning section, phase detecting section and blood flow information computing section including the parameters relating to the resolving power of blood flow color Doppler images by a resolving power control means. CONSTITUTION:The blood vessels of the intricately running blood vessels are displayed without interruptions on a color monitor 39 when the knob of the slide volume control of an operation panel 42 is set at a low-resolving power position. The parameters relating to the resolving power are controlled by a system controller 43 when the knob is successively slid to a higher resolving power side. Namely, the frequency of a reference signal is shifted to a high-frequency side by a reference oscillator 16 of a scanning section 12 and burst frequencies are decreased by a pulser 17. The delay time is shortened in a delay line 19. The band width of the reception signal is widened in the phase detecting section 13. Then, the sharp blood flow image which has an interruption but is free from out-of-focus is obtd. on the monitor 39.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic blood flow imaging apparatus capable of freely adjusting the image resolution and efficiently and accurately diagnosing a complicated blood vessel.

[0002]

2. Description of the Related Art An ultrasonic blood flow imaging apparatus uses an ultrasonic pulse reflection method (ultrasonic tomography method) and an ultrasonic Doppler method in combination to obtain a tomographic image (B mode image) and a blood image with one ultrasonic probe. Flow information (direction and velocity of blood flow) is obtained, and the blood flow is color-displayed in real time on a tomographic image.

The principle of measuring the blood flow velocity with this ultrasonic blood flow imaging apparatus is as follows. When an ultrasonic pulse is transmitted to the blood flow in the living body that is the subject,
The ultrasonic beam is scattered by red blood cells flowing at a velocity v in the blood vessel, and its reception frequency f ′ ₀ is slightly deviated from the transmission frequency f ₀ due to the Doppler effect. The frequency (Doppler frequency) f _{d that} depends on the deviation at this time is f _d = f ′ ₀ −
f ₀ = 2 · v · f ₀ · cos θ / c (c is the speed of sound, θ is the angle between the ultrasonic beam and the blood flow). That is, f
_{Since d} is proportional to the blood flow velocity v, conversely, v can be known by knowing f _d .

As shown in FIG. 3, scanning by the ultrasonic blood flow imaging apparatus is performed by the ultrasonic probes 1 to D ₁ -D.
_An ultrasonic beam is sequentially transmitted in a sector shape in _N directions of _N , and blood flow information is detected from 6 to 256 sample points SP of a specific depth in each direction of D _{1 to DN} .

In the system for detecting blood flow information at this time, as shown in FIG. 4, first, a reflected ultrasonic wave RUS from the living body P received by the ultrasonic probe 1 is received as an electric ultrasonic wave reception signal ( Echo signal). Then, this reception signal is sent to the phase detection circuit 3 after being given a delay time corresponding to a specific direction of D _{1 to} D _{N in} the reception circuit 2, and the Doppler shift signal is detected at each sample point.

Then, the Doppler shift signal at each sample point is
Frequency analysis is performed by the frequency analyzer 4 to determine blood flow information such as blood flow velocity. An image signal containing this blood flow information is sent to a DSC (digital scan converter) 5 to convert the ultrasonic scan into a TV scan, and then the monitor 6 superimposes it on the B mode image 7 to form a blood flow image. Two-dimensional real-time display. At this time, the blood flow information is color-displayed in accordance with pre-designated color conversion information (for example, the flow toward the ultrasonic probe is red, the flow away is blue, and the magnitude of the velocity is reflected in the brightness).

[0007]

However, the resolution of the blood flow image depends on the center frequency and the burst wave number (wave number of the ultrasonic transmission signal) applied to the ultrasonic transmission system, the focus strength and the scanning line density (wave number of the ultrasonic transmission signal). That is, it depends on the delay time) or the reception signal bandwidth applied to the ultrasonic wave reception system, etc., but since there are resolutions set by unique parameters by various ultrasonic blood flow imaging devices, for example, meandering When displaying the blood flow in a blood vessel that is running in a complicated manner, when a high-resolution device is used, the blood flow is displayed intermittently and cannot be connected. Therefore, it is necessary to perform scanning several times while moving the position of the ultrasonic probe to grasp the entire image of the blood vessel, which requires a long time for diagnosis.

On the other hand, when a low-resolution device is used, blood vessels do not appear to be interrupted, but detailed diagnosis cannot be performed on a specific location. For this reason, with one type of device, it is inevitable that either trouble of diagnosis or accuracy of diagnosis will be hindered.

The present invention has been made in view of the above circumstances, and an object thereof is to provide an ultrasonic blood flow imaging apparatus capable of efficiently and accurately diagnosing a complicated traveling blood vessel.

[0010]

In order to solve the above problems, the present invention provides an ultrasonic probe, a scanning unit for processing an ultrasonic transmission / reception signal and detecting a B-mode image of a living tissue, and a blood flow A phase detection unit that performs phase detection on the color Doppler image, a blood flow information calculation unit that calculates blood flow information such as the direction and velocity at each location of the blood flow, a B-mode image of biological tissue, and a color Doppler color flow of the blood flow. Ultrasonic blood flow imaging including an image display unit for superimposing and displaying images, and resolution adjusting means for controlling parameters related to the resolution of the blood flow color Doppler image in the scanning unit, the phase detection unit, and the blood flow information calculation unit Provide the device.

[0011]

In the ultrasonic blood flow imaging apparatus of the present invention, the resolution adjusting means provides the parameters for the scanning section, the phase detection section and the blood flow information calculation section including the parameters relating to the resolution of the blood flow color Doppler image. Therefore, it is possible to display an image with a desired resolution ranging from low resolution to high resolution according to the purpose of diagnosis.

[0012]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a block diagram of an ultrasonic blood flow imaging apparatus 10 according to an embodiment of the present invention. This ultrasonic blood flow imaging apparatus 10 is roughly divided into an ultrasonic probe 11 that performs a sector scan (equipped with a two-dimensional array transducer and capable of adjusting the focal point depth of the ultrasonic beam in the slice direction), a scanning unit 12, The phase detection unit 13, the blood flow information calculation unit 14, and the image display unit 15 are included.

The scanning unit 12 includes a reference oscillator 16 and a pulser 1.
7, preamplifier 18, delay line 19, adder 20
The phase detector 13 includes a 90 ° phase shifter 23, mixers 24a and 24b, and low-pass filters 26a and 26b.

The blood flow information calculating unit 14 includes A / D converters 28a and 28b, MTI (moving target indicating device) filters 29a and 29b, an autocorrelator 30, and an average velocity calculating unit 3.
1, a dispersion calculation unit 32 and a power calculation unit 33, and the image display unit 15 further includes a B-mode DSC (digital scan converter) 34, a CFM (color flow mapping) DSC 35, a color processing unit 36, and a multiplexer (switch). 39, a D / A converter 38 and a color monitor 39.

In this embodiment, a system controller 43 capable of adjusting the resolution is connected to an operation panel 42 which can be operated by the user, and the system controller 43 further includes the scanning unit 12, the low-pass filters 28a and 28b of the phase detection unit 13, and It is connected to the blood flow information calculation unit 14.

In the operation of the ultrasonic blood flow imaging apparatus 10, reference oscillation for ultrasonic wave transmission is performed in the reference oscillator 16 of the scanning unit 12, and the reference signal accompanying this reference oscillation is sent to the delay line 19. Be done. Then, in the delay line 19, a delay time related to the sector scan is added to the reference signal and sent to the pulser (transmission circuit) 20, and the ultrasonic wave transmission signal is sent from the pulser 20 to the ultrasonic probe 11.

In this way, the ultrasonic probe 11 emits ultrasonic waves US into the living body P by the sector scan.
The ultrasonic wave reflected by each tissue in the living body P is received by the ultrasonic probe 11, converted into an ultrasonic wave reception signal (echo signal) by the transducer, and then sent to the scanning unit 12.

In the scanning section 12, the echo signal is first amplified by the preamplifier 18 and then input to the delay line 19. Then, in the delay line 19, the delay time associated with the sector scan is given to the delay line 19 and is output to the adder 20 for phasing addition. The echo signal is
Here, it is divided into two, one of which is subjected to envelope detection by the detector 21 and then sent to the image display unit 15, and ultrasonic scanning is converted into television scanning by the B mode DSC.

The other echo signal is sent to the phase detection section 13 and is further divided into two mixers 24a and 2a, respectively.
Enter in 4b. By the way, the reference signal (frequency f ₀ ) from the reference oscillator 16 is input to the mixer 24a, and the reference signal input from the reference oscillator 16 to the mixer 24a via the 90 ° phase shifter 23 is input to the mixer 24b. A reference signal to which a 90 ° phase difference has been added is input and combined with each echo signal.

As a result, the low-pass filters 25a, 25
The reference signal and the Doppler shift signal (frequency f
_d) the combined signal (frequency 2f ₀ + f _d) is input, wherein each high-frequency components are removed, and the phase is detected. Then, the real component of the frequency f _d from the low-pass filter 25a is also the imaginary component of the frequency f _d from the low-pass filter 25b is respectively fed to the bloodstream information calculation unit 14 as the phase detection output signal.

The phase detection output signal is supplied to the blood flow information calculation unit 14
First, the A / D converters 28a and 28b digitize the signals, respectively, and then the MTI filters 29a and 29b remove unnecessary fixed reflection signals other than the blood flow (for example, the heart wall). After the autocorrelation of the signal is calculated by the autocorrelator 30, the average velocity calculation unit 31, the dispersion calculation unit 32, and the power calculation unit 33 respectively calculate the average Doppler frequency (that is, the blood flow at that place) of each position of the blood flow. Average velocity), variance (degree of Doppler spectrum disturbance) and power (strength) are calculated in real time.

The blood flow information obtained in this way is then sent to the CFM DSC 35 in the image display section 15 and the ultrasonic scanning is converted into television scanning. The blood flow information converted into television scanning is then sent to the color processing unit 36. The color processing unit 36 sets color conversion information specific to the device (for example, the flow toward the ultrasonic probe is red and the flow away is blue). , The speed is reflected in the brightness, the variance is divided into levels by the hue of green, etc.) and a memory is stored, and appropriate color information is added to the input blood flow information.

The blood flow information including the color information and the B-mode image information output from the B-mode DSC 34 are both input to the multiplexer 37, and the information displayed by the multiplexer 37 is appropriately switched. And output. Then, the output information is converted into an analog signal by the D / A converter 38, and the color monitor 39 displays the B-mode image in black and white gradation and the blood flow information in color.

By the way, in this embodiment, since the system controller 43 capable of adjusting the resolution is provided, for example, in the operation panel 42 provided with the slide volume 45 capable of setting the resolution as shown in FIG.
First, on the low resolution side, the knob 4 of the slide volume 45
6 together, as shown in FIG. 6B, the blood vessel (blood flow) 49b, which has a low resolution and is blurred at a low resolution, but which is bifurcated and complicates running, is interrupted. Displayed without.

Here, the resolution of the image is the center frequency and the burst wave number applied to the ultrasonic wave transmission system in the scanning unit 12,
It is determined by the focus strength and scanning line density (that is, delay time) required for transmission / reception, or the reception signal bandwidth applied to the ultrasonic wave reception system in the phase detection unit 13 and the blood flow information calculation unit 14.

Therefore, when the knob 46 is gradually slid toward the high resolution side, the command for increasing the resolution of the image is transmitted to the system controller 43, and the system controller 43 appropriately scans the scanning section 12, the phase detection section 13, and An instruction is sent to the blood flow information calculation unit 14 to adjust the parameters so that the image has high resolution. The adjustment of the resolution here is performed in the slice direction (direction orthogonal to the scanning direction of the ultrasonic beam).

That is, in the scanning unit 12, if the frequency of the reference signal is shifted to the high frequency side by the reference oscillator 16, the center frequency of the ultrasonic wave is also shifted to the high frequency side, and the resolution is increased. Further, in the pulsar 17, the resolution is improved by reducing the burst wave number of the ultrasonic transmission signal. Further, in the delay line 19, the degree of ultrasonic wave convergence (focus) is reduced by shortening the delay time given during transmission and reception.
Is increased, the interval between scanning lines (raster) is narrowed (the density of scanning lines is increased), and the resolution is improved.

In addition, if the lower limit of the high frequency cut off in the low-pass filters 25a and 25b of the phase detector 13 is raised, the received signal bandwidth is widened and the resolution becomes high. When the received signal bandwidth changes, the blood flow information calculation unit 1
Since the system of calculation in the whole 4 must be changed, the system controller 43 has the blood flow information calculation unit 14
Also informs the deviation of the received signal bandwidth.

In this way, when the above parameters are adjusted by the instruction of the system controller 43 to improve the resolution of the image, as shown in FIG. 2 (C), (D), (E), the blood of each figure is sequentially displayed. Image 49c, 49d, 49e
However, as the gap between breaks increases, it becomes sharper with less blur.

Therefore, in FIG. 2E, which has the highest resolution, for example, the region of interest ROI in which the blood flow is disturbed and a thrombus is suspected can be closely examined.

As described above, according to the ultrasonic blood flow imaging apparatus 10 of the present embodiment, the knob 46 of the slide volume 45 is set to the low resolution mode at the beginning of diagnosis so as to grasp the entire image of the blood vessel without interruption, Then, by gradually shifting to the high resolution mode, a sharp blood flow image with no discontinuity but no blurring can be obtained, and a site suspected of disease can be precisely diagnosed. Therefore, as compared with a device fixed at low resolution, accurate diagnosis can be performed, and as compared with a device fixed at high resolution, the whole image of the blood vessel can be grasped at a glance, and the diagnosis time can be shortened. .. Then, in the low resolution mode, the power of the device is increased to S /
The N ratio can be restored to the level before the low resolution mode.

As a matter of course, the direction for adjusting the resolution is not limited to the slice direction, but can be the depth direction in the scanning direction, and the resolution setting means on the operation panel 45 is not limited to the slide volume. It may be a rotary switch, a touch switch, or the like.

In addition, when detecting blood flow information, not only the autocorrelation method of this embodiment but also FFT (Fast Fourier Transform) or cross-correlation method can be used, and the ultrasonic probe is a two-dimensional array. Instead, it may be a one-dimensional array. further,
The ultrasonic probe is not limited to electronic scanning, but the center frequency, burst wave number, and transmission / reception bandwidth of the transmitted ultrasonic waves can be changed using a mechanical probe.The scanning method is not only sector scanning, but also linear scanning and convex operation. And so on.

[0035]

As described above, the ultrasonic blood flow imaging apparatus of the present invention can display an image with a desired resolution ranging from low resolution to high resolution. It is possible to perform an efficient diagnosis by grasping the whole image, gradually increasing the resolution, and inspecting in detail when an abnormality is recognized, shortening the diagnosis time and achieving accurate diagnosis.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an ultrasonic blood flow imaging apparatus according to an embodiment of the present invention.

FIG. 2A is a plan view of a slide volume on an operation panel of the ultrasonic blood flow imaging apparatus, and FIGS.
(E) is a blood flow image at each point from the low resolution mode to the high resolution mode of the slide volume.

FIG. 3 is a raster diagram in an ultrasonic sector scan.

FIG. 4 is a configuration diagram of an ultrasonic wave reception system of the color Doppler tomography apparatus.

[Explanation of symbols]

 11 ultrasonic probe 12 scanning unit 13 phase detection unit 14 blood flow information calculation unit 15 image display unit 43 system controller 45 slide volume 46 knob

Claims (2)

[Claims] 1. An ultrasonic probe, a scanning unit for processing ultrasonic transmission / reception signals and detecting a B-mode image of a biological tissue, a phase detecting unit for performing a phase detection on a color Doppler image of blood flow, and a blood detector. A blood flow information calculation unit that calculates blood flow information such as the direction and velocity at each location of the flow, an image display unit that displays the B-mode image of the biological tissue and the color Doppler image of the blood flow in a superimposed manner, and the scanning unit. An ultrasonic blood flow imaging apparatus comprising resolution adjusting means for controlling parameters relating to the resolution of a blood flow color Doppler image in a phase detection unit and a blood flow information calculation unit. 2. The ultrasonic blood flow imaging apparatus according to claim 1, wherein the resolution adjusting unit includes a slide volume capable of sliding a knob between a low resolution mode and a high resolution mode.