JPS5889242A - Ultrasonic measuring method and apparatus of blood flow speed in combination with echo amplitude image - 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 The present invention generally relates to the simultaneous imaging and imaging of biological tissues (e.g., blood vessels, ventricles, etc.) for practical purposes by a combination of ultrasound Doppler blood flow measurements and ultrasound echo amplitude imaging. The present invention relates to the above combination for obtaining measurements of blood flow velocity within biological tissues. This combination is obtained without any reduction in the maximum blood velocity measured by the pulse-r-deci method, and the continuous P-dec method can also be used. In the latter case, there is no limit to the maximum speed that can be measured.

The method of ultrasound blood flow rate measurement (hereinafter referred to as "Doppler measurement") based on the F-Shirra principle and the method of echo amplitude imaging (hereinafter referred to as "echo imaging") using ultrasound pulses are considered to be well known. The present invention relates to the combination of these simultaneous measurements.
This can be realized by slightly modifying the LIllJ constant devices and interconnecting them more to a central control unit.

an image of the biological tissue is shown on a suitable display screen;
The range over which blood flow rate is measured is shown on the same screen. An effective spectral analysis of the received Doppler signal is also shown on the screen and can be printed on a suitable printer, perhaps by cylinder printing.
be outed.

It is an object of the present invention to utilize echo amplitude images to determine the range in which blood velocity is measured, thereby simplifying the aiming of the ultrasound head or transducer during V-dela measurements of blood velocity. be.

By combining blood velocity measurements with vessel dimension measurements, it is believed that the actual flow rate in the vessel can be calculated.

A very important consideration in using the type of equipment involved is that the Doppler signal is provided in an audible format, for example by a loudspeaker. 1lIIIf, the physician performing the procedure initially, and 9% of the time, makes more detailed measurements before focusing on imaging points within the blood system, where the focus is on finding the bands contained in the audible Doppler signal. Use as much information as possible. Therefore, it is extremely important that the audible Doppler signal is not disturbed or distorted by chance.

Real-time analysis based on the amplitude of echoes from short ultrasound pulses.
Equipment that creates two-dimensional imaging of biological tissues in time is commercially available. There are two types of such known instruments: a) Instruments based on phase-controlled transducer arrays or partial sweeps obtained by mechanically moving transducers.

b) Instruments based on linear sweeps obtained by electronic selection of elements in a linear play of transducers or by linear mechanical movement of a single transducer.

Blood flow velocity super wave gutter? Measuring equipment is also commercially available and there are two basic methods: a) ultrasonic pulses, which allow depth resolution along the ultrasonic C-5 so that small range velocities can be measured; . Multi-depth t-thumping can also be used so that speed can be side-wheeled at several depths. This method has the disadvantage that the maximum velocity that can be measured is limited by the pulse repetition rate or frequency used.

b) Continuous ultrasonic measurements; this method does not seem to provide any depth resolution along the ultrasonic curve. Alternatively, there is no limit to the maximum speed determined by method a above.
Commercial instruments are available that combine a) and b).

Instruments that combine echo amplitude imaging and Doppler blood velocity measurements are also commercially available. The following three principles are used: a) Interrupt mode. The image is frozen on a suitable screen under manual control and an ultrasound probe V is utilized for Doppler measurements of blood velocity.

b) All emitted second ultrasound pulses are used for Doppler velocity measurements and intermediate pulse echo amplitude imaging. That is, the pulses alternate between Doppler measurements and knee imaging.

C) Finally, there appears to be a proposal for a design in which several Doppler pulses are emitted as a contiguous train with periodic interruptions for single-echo amplitude imaging pulses.

The above methods of correlating echo imaging and Doppler measurements have the following deficiencies and disadvantages: 1) When the image is frozen in the interruption mode Gives an incomplete representation of the range.

2) The alternating emission of the Doppler pulse and the Sosoparnu reduces the emissivity of the Doppler pulse and thus the maximum velocity measured.

, (Doppler pulse measurement) 6) In the third method shown, there is only a slow update of the image, which creates directional limitations on the lens when the object or/and the measuring spatula V is moved. Another serious disadvantage of this method is that the imaging signal is audible, so that signal listening is disturbed. In methods b) and c), the maximum velocity measured is Continuous Doppler field constant signals, which are meant to be determined by the number of keying excursions in the field, may not be used.

These deficiencies are avoided in the present invention by allowing the use of high image frequencies (eg F120Hz). Furthermore, both pulsed and continuous Doppler measurements are used, and the pulse repetition rate in pulsed mode does not need to be reduced from what it is in pure Doppler measurements.

Thus, given the background of known methods, the present invention provides, as a starting point, simultaneous echocardiography using ultrasound pulses to investigate living biological tissue during exercise, such as cardiac function. A method of ultrasound blood flow measurement (Doppler measurement) based on the Doppler principle, which is combined with amplitude imaging (echo imaging), said Doppler measurement and echo imaging having an image quality that is acceptable for echo imaging. The image information from the echo imaging and the Doppler are updated at a sufficiently high frequency and are performed virtually for a short and possibly variable time such that the Doppler measurement occupies a sufficient portion of the time to measure velocity with the desired accuracy. A display of the measurement range or measurement point for the measurement is displayed in real time on an acid IIIII/AIF screen or the like, and the central device acts to synchronize the measurement and the echo imaging. 1
The method is such that more than one transducer is activated at any given moment to perform either rdera measurements or echo imaging. The novel feature of the method according to the invention is primarily that the Doppler measurement is carried out using ultrasonic waves above the image field.
In order to partially sweep the complete Kt in the time period. K is interrupted while constituting an important part and that the directly measured Doppler signal is used all the time or part of the time to make an estimate in place of the directly measured Doppler signal. be.

Other features according to the invention are indicated in the claims, and the invention also encompasses an apparatus for carrying out the method.

The invention will be explained in detail below with reference to the drawings.

FIG. 1 shows a block diagram of an apparatus implementing the method according to the present invention. The apparatus includes a central controller 4, an echo amplitude imaging device 2 for two-dimensional imaging in real time, and
It consists of a Doppler device 1 with a combination device 5 denoted m (t-singing signal estimator) and an instrument, such as a cathode ray tube screen 3, for displaying images and Doppler spectra.

Both the Doppler device 1 and the imaging device 2Fi are switched on and off electronically. Both devices are controlled by a control device 4 which operates according to principles known per se for such control. In operation, control device 4
The Doppler measurements are interrupted for short time intervals (eg, 15 milliseconds) to perform a complete or partial sweep of the ultrasound beam over the field or image area.

Directly measured Doppler signals can be used for evaluation instead of Doppler signals during all or part of the time only when Doppler measurements are not available, which may occur due to K, e.g. interruption times, high-pass filter transients, etc. It is used to give. Ratings are made by M8R@Oki5.

The echo amplitude image produced in each sweep is stored in a suitable electronic image memory which is continuously scanned to display the image on a suitable screen. Such storage methods are used in some commercial instruments. The control device 4 provides the time structure of the Doppler and imaging measurements (echo imaging) as well as the structure of the signals for appropriate display and printout.

This will vary depending on the shield and imaging equipment used, and the design is based on the same methods of control equipment found in other time-sequenced instruments.

Also shown schematically in FIG. 1 is a transducer 10a and a transducer array 10 for echo imaging, which are described in more detail in FIG. 4 or 5, for example, described below. be able to respond to things.

The function of the apparatus of FIG. 1 will be explained in detail later with reference to FIGS. 6 to 9 at 41.

Figures 2 and 6 are range @21 (Figure 2) and range i!, respectively. 131 (FIG. 3), in which blood velocity is measured by a phase-controlled variable I1%-array.

These IIK show hearts 25 and 35 with aortas 26 and 36, respectively, and lines 27.28.29 and -37,3B, 39Kj, respectively.
The image 74 is shown.

The same ultrasound heads 20 and 30 are used for Doppler measurements and echo imaging, respectively. In Figure 2,
The ultrasonic beam 22 for measuring Pdela is directed straight ahead. In this case, it is possible to connect several elements of the transducer array to one single transducer by suitable selectors (relays or electronic switches).

In FIG. 3, the direction of Doppler measurement 33 is offset from the centerline. To obtain this, the signal must be phase-controlled in all transducer elements 30, for example by the same electronic circuit used for phase control during imaging F! However, the method according to FIG. 2 yields better sensitivity in the case of less accurate and noisy phase control circuits.

It is also possible to use a separate transducer 4G for Doppler measurements, as shown in FIG. . FIG. 5 shows a linear image sweep by a linear transducer array 50 and another Doppler transducer 50aK. The transducers 50 and 50a are shown in contact with the patient's skin 52 with a vein 56 shown below, the image field V of this vein being limited by lines 57, 58 and 59. That is, it is placed within the image range. A measurement range 51 for Doppler measurements is shown inside a vein 56 .

This arrangement with a separate Doppler transducer has, inter alia, the advantage that the rDella transducer Sea is optimized to obtain a good sensitivity [by Doppler measurements] with a separate mechanical imaging sweep. A fixed Doppler transducer 50a is used because it may be difficult to stop the movable imaging transducer fast enough for Doppler measurements.

In this regard, reference is first made to FIG. 9, which shows an exemplary time interval between echo imaging and velocity measurement. An image time of 15 milliseconds and an r-dela time of 65 milliseconds yields an image velocity of 20 mm.

By decreasing the Doppler time to say #i18 ms, the velocity is increased to 30 ms. Other details shown in FIG. 9 will be explained later.

As previously mentioned, the directly measured Doppler signal is used to create a substitute estimate for the Doppler signal in the absence of the Doppler signal at all times. In FIG. 6, only during the above-mentioned interruption time or a longer part of the time,
For example, it is shown how the evaluation replaces the directly measured Doppler signal at all times. As shown, the M8E% position 65 passes the Doppler signal measured directly at the top (solid arrow) position and the M8E% position 65 at the bottom (dotted arrow) position.
8, an evaluation signal is passed from the device 65 to the next part of the device, for example the control device 4, so as to be then displayed on a display screen, such as screen 3 in FIG.
It is incorporated into a successfully parallel signal path 60 that transfers the measured Doppler signal directly from wire 61 to switch 62 . If the device according to the general idea of the invention is configured to use the evaluation signal all the time, switch 6
2 is permanently in its lower position KTo! 0, i.e. it is likely that only a signal path through the device 65- in M8 is sufficient. When there is a switch 62, its appropriate control selects the portion of time in which the evaluation signal replaces the Doppler signal where it is directly measured. can do.

The evaluation is based on the nature of the Doppler signal measured, e.g. with the relevant interruption time, i.e. before and after this time.
It is generated in an M,8R device 65 corresponding to device 5 of FIG. An estimate of a defective Doppler signal can be made, for example, in the following way: a) a signal estimate based on the characteristics of the Doppler signal, e.g. at the end of the Doppler time, e.g. by adding broadband noise to a controlled filter network; can be generated. This is shown in FIG. Shown in FIG. 7 is a broadband noise generator 73, a control filter 72, and a device 71 which serves to generate filter parameter signals that control the instantaneous filter characteristics of filter 72. The filter is designed, for example, as a transverse filter in which the tarsing weights are adjusted by filter parameters to obtain the desired spectrum.

b) According to FIG. 8, the directly measured Doppler signal is continuously stored in the digital storage 82, for example by the cooperation of an address counter 85 and an address jump controller 84. When an interruption is made for an image sweep, the last stored portion of the Doppler signal is read out and utilized for evaluation during the imaging period.

In the embodiment of FIG. 8, devices 82, 83 and 84 are considered to constitute the M8g device 5 shown in FIG. In a corresponding manner, the above embodiment of FIG.
Devices considered to constitute devices71,72,7
3 and 74 included.

The "direct measurement" Doppler signal shown by 61 in FIG.
It passes through a high-pass filter, for example filter 81 as shown in FIG. For Doppler pulse measurements, there must be an insertion filter before and after the high-pass filter.

In order to obtain a smooth transition between the evaluated Doppler signal and the directly measured Doppler signal, the signal may be multiplied by a window function as shown at 63 in FIG. By this method, the signal level is gradually reduced to zero before switching, and then again gradually increased to full magnitude after switching. This is illustrated in Figure 9, which shows how the signal level changes when converting from Doppler measurements to echo imaging and vice versa. An overlap between the directly measured Doppler signal and the evaluation signal is also obtained if, while decreasing the level of the direct signal, the conversion from the direct signal to the evaluation signal begins to increase the level of the evaluation signal. In the conversion from the evaluation signal to the direct signal, an increase in the level of the direct signal is thereby initiated, but the level of the evaluation signal is reduced. This smoothing or adjustment of the signal transition is important for the KJI at the end of each interruption period, ie when changing between the evaluation signal and the directly measured Doppler signal.

In order to suppress strong reflections from the tissue boundaries of biological tissues, a high-pass filter 81 with high part selectivity is used at the P-shield 5.
(Fig. 8). When starting Doppler measurements after the imaging time (interruption time), there will be a transient in the high-pass filter. Directly measured Doppler signals may not be applicable during the high-pass filter transient time, so the evaluation must also be used during this time. The evaluation time therefore appears to be longer than the image sweep time shown in FIG.

The transient time of the high pass filter is reduced by signal multiplication before the filter by a window function shown at 83 in FIG. The signal level before filter 81 is then increased from zero to its fixed magnitude.

Reduction of the transient time in the high-pass filter is also obtained by changing the frequency response of the filter during the transient time. An example of a prefilter network 100 that accomplishes this is shown in FIG. 11, where K incorporates a voltage controlled resistor 102 with a control signal input 103.

When a Doppler measurement begins, the value of control resistor 102 is very low, ie, equal to zero, so that the amplification of filter 100 is low and the interruption frequency is high. The value of control resistor 102 is then increased to its maximum value two seconds after switching on the VDEL device after the image sweep.

Furthermore, FIG. 11 shows a capacitor 101 and a control resistor 1.
02, the required buffer amplifier 104 is shown between the pre-filter network and the actual high-pass filter 105, and its transient spread should be reduced. be. The pre-filter network is incorporated as part of the high-pass filter.

It is clear that in the prefilter network 100 of FIG. 11, the capacitor 101 is a variable capacitor and is voltage controlled by the resistor 6! The important benevolence here is the ability to obtain the described trait abduction.

FIG. 12 shows a preferred transducer array for use in five positions according to the present invention, which is similar to the embodiment of FIG.
# is closely related. As shown in the example of FIG. 12, a number of transducer elements are placed along the line. The central 16 elements, or perhaps all elements, are used for continuous Doppler measurements, with half of these elements being transmitting elements and the other half being receiving elements. This is obtained by electronic switching or perhaps by means of methods known per se. In pulse motion of Doppler measurements, both halves, each containing 8 transducer elements, are interconnected such that 16 central elements operate in parallel. During echo imaging, the total number of transducer elements is assumed to be operated in a manner of control known per se. It is clear that this array has transducers other than the 32 transducers shown in Figure 1.2. Furthermore, with continuous Doppler measurements, the breakdown of the number of transducers used may differ from the situation where half of the elements are used for transmitting and the other half for receiving.

Finally, it should be mentioned that the ratio of the respective time intervals for Doppler measurements and echo imaging is different from that described with respect to FIG. Thus, depending on the desired precision in velocity measurements, Doppler measurements can occupy a smaller portion of the time than the imaging (interruption time).

[Brief explanation of the drawing]

FIG. 1 is a diagram of an apparatus for carrying out the method according to the invention, FIG. 2 is a schematic diagram of a first type of image display by the apparatus according to the invention 11, and FIG. 4 is a schematic diagram showing a variation of the arrangement of FIG. 2 with another P-dela transducer; FIG. 5 is a linear transducer array for echo imaging and another Doppler a schematic diagram showing another form of display based on the use of a transducer;
Figure 6 is straight! 7 is a schematic diagram illustrating one embodiment configuring the evaluation of the Doppler signal; FIG. 8 is a schematic diagram illustrating another embodiment configuring the evaluation of the Doppler signal; 9 is a schematic diagram showing the time division between echo imaging and Doppler measurement, as well as a schematic diagram illustrating some signal processing (rumor function); FIG. 11 is an example of a filter network that should be arranged in front of the high-pass filter of the device; FIG.
The figure is an example of a transducer array for use in a device according to the invention. Explanation of symbols 1... Doppler measurement device; 2... Echo imaging device; 3
...Cathode ray tube screen; 4...Central control unit; 5
...M2R (t-singing signal estimator)
Agent Akira Asamura 59 Fio, 5 throat! Fig, 12 Procedural Amendment (Toge) December 23, 1980 Dear Commissioner of the Patent Office 1, Indication of Case 1988 Patent Application No. 98827 Ultrasonic Measuring Method and Apparatus for Blood Flow Velocity 3, Person Making Amendment Case and Relationship of Patent Applicant Address Name C Name), 'Ngumetsu) Akchi Seven Rus Power Pet 4,
Agent 5, date of amendment order, Showa year, month 1, 6, number of mu marks to be increased by amendment 7, subject of amendment -2 (

Claims (1)

Claims: (1) combined with simultaneous echo amplitude imaging (echo imaging) using ultrasound pulses to investigate living biological tissue, especially during exercise such as cardiac function; ,
Ultrasonic blood flow measurement based on the Dosora principle (Doppler measurement)
The method comprises: the Doppler measurements and knee imaging are updated at a sufficiently high frequency for an acceptable image quality, and the Doppler measurements cover a sufficient portion of the time to measure velocity with the desired accuracy. The image information from the echo imaging and the display of the measurement range or measurement point for Doppler measurements - real-time on an IIAi 11-pole screen, etc. and where the solid instrument serves to synchronize Doppler measurements and echo imaging, and where one or more transducers perform either Doppler measurements or echo imaging at any given time. In said method, the Doppler measurement is activated at a moment when the image field r is interrupted for a complete or partial sweep of the ultrasound beam over the image field r, constituting a significant part of the hour, and the direct measurement 2. A method according to claim 1, characterized in that the Doppler signal determined is used to produce an estimate in place of the Doppler signal determined directly during the whole time or part of the time. (2) An evaluation is made during each interruption time based on the Dodera signal-line for a certain period of time combined with the interruption time concerned, and said evaluation is made during the interruption time by the Yf signal specified in column II. A method according to claim 1, characterized in that the method is characterized in that the method according to claim 1 is replaced by (3) characterized in that the evaluation is made by continuously storing the Doppler signal in the storage device, and that the last stored portion of the Doppler signal is read out from the storage device and used as the evaluation during each interruption time; The scope of claim No. (
! ). (4) characterized in that the instantaneous filter characteristics of the control filter are adjusted based on the characteristics of the Doppler signal, e.g. its electric flux vector, and the control filter is provided with broadband noise such that the filter output provides an estimate of the Doppler signal. A method according to claim (1) or (r). (5) A number of imaging pulses, substantially more than one, are transmitted during each interruption period. A method according to any one of paragraphs (1) to (4). (6) Continuous mode is a method in which the selection between pulse mode Doppler measurements is made regardless of echo imaging, and no! A method according to claim (6), characterized in that in the case of Doppler measurement in Luss mode, the pulse repetition rate is independent of the pulse repetition rate of echo imaging. In any one of paragraphs (1) to (6) above, a high-pass filter is used to attenuate unnecessary Doppler signal components due to, for example, relatively strong ultrasound beams and biological tissues with slow motion. 4. The method according to item 1, wherein the evaluation is guided into the signal path after the high-pass filter. (8) After each interruption period, the high-pass filter characteristic is A method according to claim 7, characterized in that the cutoff frequency is changed from the increased cutoff frequency to the normal cutoff frequency during a time period of the same magnitude as the transient time of the filter. (9) High-pass filter characteristics the change is carried out in a pre-filter network consisting of a series capacitor and a parallel resistor, the capacitors and/or resistors being voltage controlled and supplied with a control voltage in the order in which said change of the filter characteristics is carried out; A method according to claim 8, characterized in that a window function is introduced before the high-pass filter, said window function reducing the transient time of the high-pass filter. A method according to claim 7. (b) In the conversion between the direct Doppler signal and the evaluation, in particular at the end of the evaluation time, the adjustment of the directly measured Doppler signal or/and the evaluation signal, i.e. A method according to any one of claims 1 to 41, characterized in that smoothing is provided. (6) 1 to 9 refers to smoothing of a plurality of signals. A method according to claim (b), characterized in that the pulse shape is created by multiplication by a suitable table window function, such as a cosine function. an echo imaging device (2) combined with a device (1), such as a cathode ray tube screen (3) for displaying images in real time, and one or more ultrasound transducers each for Doppler measurements and echo imaging. and a control device (4) for synchronizing Doppler measurements and echo imaging, the device comprising: a device (4) in the control device (4) for interrupting the Doppler measurement for a period of time constituting a significant part of the period; and a device (5) for making an evaluation of the constant Doppler signal, the said evaluation occurring at all times. or the device (5) which replaces a directly measured Doppler signal for a portion of the time. □(b) The device (5) for making the evaluation is configured to produce an evaluation based on the signal curve for a certain period of time combined with the associated interruption time during each interruption time.
Device according to claim 2, characterized in that the evaluation replaces the directly measured Doppler signal during the interruption time. (g) characterized in that it has a storage device for continuously storing Doppler signals, and is adapted to have the last stored portion of the Doppler signals read and read so as to make an evaluation during each interruption time; An apparatus according to claim (b). (2) Device for measuring Doppler signal characteristics (7 in Figure 7)
1), a control filter (T2) with an instantaneous filter characteristic that is adjusted based on the characteristics of the Doppler signal, e.g. ) A K-connected broadband noise source (73). (b) Any one of claims 1 to 2 that includes a high-pass filter (81 in FIG. 8) designed to attenuate unnecessary Doppler signal components. A device according to the invention, characterized in that the evaluation is introduced in the signal path (61 in FIGS. 6 and 8) after the high-pass filter (81). (to) The high-pass filter characteristic is adapted to be changed from the increasing frequency limit to the normal cut-off frequency during a time period of the same magnitude as the transient time of the high-pass filter. Equipment as described in item (b). (6) A pre-filter network (100) is incorporated into the high-pass filter, said pre-filter network being connected to a series capacitor (101).
) and a parallel resistor (102), the capacitor t
i/and the resistor (102) are voltage controlled and supplied with a control voltage (103) that is To9 and that changes the filter characteristics. device by. A patent claim characterized in that it has a device (83 in Figure 8) for introducing a window function in front of the high-pass filter (81), and the window function reduces the transient time of the high-pass filter. Scope of equipment as described in paragraph (b). (2) At the transition between Doppler measurement and echo imaging, in particular at the end of the evaluation time (echo imaging), a device (6 Device according to any one of claims 1 to 6, characterized in that it has the following features: 2. Device according to claim 2, characterized in that the smoothing device (63) is adapted to multiply the signal or signals by a suitable window function, for example a cosine function. Hoop The transducer array has a number of transducer elements placed along a straight line, some of the transducer elements act as transmitters in continuous Doppler measurements, while the rest of the transducer elements Claims 1 to 3, characterized in that the part operates as a receiver and that the entire number of transducer elements in the array is adapted to operate during echo imaging. 2) Devices according to any one of the paragraphs.