JPS60148545A - Medical apparatus suitable for analysis of brain pulse from head skeletal wall - 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 Field of the Invention The present invention is suitable for analyzing cerebral pulses from the cranial wall of various types using ultrasound reflected from the internal structures of the brain, essentially blood vessels. The present invention relates to an ultrasonic medical device.

Devices of this type are put to use for the assessment of the functional state of the brain's inorganic tissues and for displaying the entire circulatory activity of the brain on a display such as, for example, a cathode ray tube TV screen.

Description of prior art Glazing techniques for examining the brain are known.

The oldest technique is electroencephalography, which uses many '1111 electrodes attached to the scalp to measure changes in brain electrical potential.

Radiological methods use an X-ray scanner in conjunction with tomographic densitometry and cerebral artery delineation to display vessel bifurcations.

The tangent method utilizes selective fixation of isotopes and is a suitable method using, for example, positron emission tomography.

Ultrasound methods use A, B and Doppler techniques.

Modern nuclear magnetic resonance methods require a perfectly constant reference field, making their use extremely difficult.

Generally speaking, most modern nuclear domain methods are complex, difficult to use, expensive and often risky for the patient.

As is well known, classical techniques such as electroencephalography have limitations in recent years when it comes to analyzing target parameters.

Doppler ultrasound provides a local rather than a comprehensive assessment of circulatory phenomena.

It should be recognized that local ultrasound pulse wave recording of the brain is necessary depending on a number of biological factors, namely (1) the quality of the heart pumping action, (2) the quality of the vascular system, (4) Qualitative changes in vascular resistance due to various effects, (5) Qualitative changes in cerebral blood vessel flow velocity, (6) Changes in intracranial pressure, and (7) Changes in brain tissue density and elasticity.

The purpose of the present invention is to improve the function of certain tissues, such as the elasticity of arteries and the responsiveness of blood vessels to internal and external stimuli, such as absorption of drugs, inhalation of gases, without causing any harm to the patient. The above characteristics can be easily, quickly, and inexpensively
and can be evaluated iteratively if necessary,
and a medical device that allows testing of the local ultrasound pulse wave delineation state of the brain through ultrasound excitation and testing of the individual responsiveness of different regions to procedures by combining or combining various responses, comparing, etc. The goal is to provide the following.

SUMMARY OF THE INVENTION The present invention is a medical device suitable for analyzing cerebral pulses from the cranial wall, comprising a transceiver-ultrasonic transducer and adapted for introducing a series of excitation pulse streams to said transducer. an oscillator, an amplifier having a gain varying according to a predetermined law and connected to the output of the transducer, and an excitation pulse responsive to and received by the transducer; The device consists of a circuit for separating a series of echo streams, a filter system with a plurality of F-wave channels, and a circuit for processing the detected signals.

This medical device is therefore used to detect a series of echo flows that are related to the state of the ultrasound diopter to be analyzed, for example by comparison with a reference curve or reference value. By detecting and integrating successive homologous echoes, a curve representing the emission of each echo at that time can be obtained. The separation of the echoes within the four isolation ports can be adjusted or non-adjustable,9 co-located or not co-located, and is effected by a set of windows provided to isolate the useful echoes. . Such separation is all easier if the echoes have been amplified to compensate for the attenuation beforehand.

According to another feature of the invention, the medical device has a gain correction circuit connected to the gain control input of the amplifier;
This gain correction circuit is synchronized by a synchronization signal generator to vary the gain of the amplifier as a function of time and/or other physical parameters.

In order to transmit the signal in time, it is often used to connect the separation circuit to an automatic circulation circuit. This circuit controls the automatic scanning of a series of echoes directed into the separation circuit by the amplifier and transducer in response to each excitation pulse delivered by the transducer in order to separate the various echoes.

According to another feature of the invention, the processing circuit includes an analog-to-digital converter connected to the output of the P-wave channel of the filter device and a processor controlling the display device (CRT screen) and/or printer. It consists of means suitable for introducing synthetic digital signals (for example, synthetic digital signals).

To facilitate measurement and analysis of the two hemispheres of the cerebrum, this device is constructed from at least two parallel connected systems, each consisting of a transducer, an amplifier, an isolation circuit, and a filter circuit. It is advantageous if two simultaneous analyzes are possible.

Other objects and advantages will become apparent from the following description of the accompanying drawings and corresponding embodiments of the invention. And the novel features will be clearly pointed out by the enclosed text of the appended claims.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, an ultrasound medical device for analyzing brain waves at different depths from the cranial wall consists of a transducer 1 which acts as a transceiver. This transducer receives an excitation pulse signal provided by an oscillator 2 supplied from a high voltage power supply circuit 5. This signal is supplied by the oscillator 2 to the transducer 1, resulting in the transmission of an ultrasound signal, so that the transducer 1 acts as a transmitter. Instead, the transducer 1 receives a series of bouncing response signals or echoes from different regions of the volume analyzed by the transducer 1.

The echo signal is directed by a gain correction path 6 to an amplifier 3 with a gain that varies as a number of tracks in time.

As a result, variations in the attenuation of the waves occur due to the different regions of the volume which answer or analyze the attenuation of the signal emitted by the transducer 1 according to the distance of the surface to be detected.

The output of the amplifier 3 is connected to a signal separation circuit 7 having N outputs connected to filters 91 to 9N, respectively. The send pulse oscillator 2 and the echo signal separation circuit 7 are maintained in a synchronous relationship by a synchronization signal generator 4.

The separation circuit 7 has as many outputs as there are signals to be separated from the series of echo signals. This number can be greater than strictly necessary and certain channels can be left unused depending on the application. In this way, circuit 7
generates a signal corresponding to each particular echo.

This echo is of interest to the processing circuitry and is displayed on a cathode ray screen or printed out by a printer or plotter, preferably after a gamma digital conversion.

In particular, the transducer 1 is an ultrasound transmitter-receiver.

This is conveniently composed of lead zirconide-tanide,
It operates at frequencies between 1.5MHz and 2.5MHz. Physical medicine research has shown that it is difficult to scan the entire brain with transducers and that it is advantageous to limit scanning to one transducer per cerebral hemisphere. , preferably placed against the side wall of the patient's head.

The pulse generator 2 then pulses at a relatively high voltage, such as 700 volts, to the transducer 1, which acts as a transmitter. The pulses provided by the generator 2 are sufficiently spaced from each other to initially deliver one pulse to the Fi cranium. It then receives an echo signal from this pulse that is reflected by various ultrasound diopters in the brain. Generally, ultrasound diopters in the brain are blood vessel walls, membranes, etc., and changes in the reflection characteristics of these diopters under the effect of cardiac systolic pressure generate echoes that change over time.

After delivery of the pulse, the transducer 1 is excited by an echo signal that reflects from the operculum in response to this input pulse. These echoes are converted into electrical signals by a transducer and sent to an amplifier 3.

The order of the pulse signals provided by the generator 2 is such that reception of the echoes, ie at least the most effective order of reflections of the echoes, takes place. As mentioned above, ultrasound analysis by applying pulses to the brain is effective only in one cerebral hemisphere, and only highly attenuated echoes, which are difficult to process, are obtained from the opposite mt+1,000 spheres.

Considering, on the one hand, the attenuation of the pulse signal emitted by the transducer 1 to be propagated through the brain, and, on the other hand, the attenuation of the echo signal reflected from various diopters in the brain depending on the input pulse signal on the reflection path. , the gain of the amplifier 3 is set to substantially logarithmic gain correction, since the attenuation of the signal in the brain is an exponential function of the distance separating the wave transmission point and the wave input point into the brain. The gain correction circuit 6 converts it into a function of time.

In the simple 7i method, the gain of the amplifier 6, controlled by the gain correction circuit 6, increases at an accelerating rate during one cycle, thus following the order of the echoes produced by the same excitation pulse. A more accurate method can be observed if the attenuation of the volume to be analyzed remains substantially invariant with distance from the transducer.

The gain curve provided by the gain correction circuit 6 is adjusted substantially according to the experimentally determined scissor rule.

The gain correction circuit 6/d is also connected to the synchronization signal generator 4 and modifies the position of the gain curve according to the functional state of the transducer 1 and the amplifier 3.

A separation circuit 7 is introduced in the series-to-parallel converter which receives the echo signals in sequence after being amplified by the amplifier 5 in order to separate these echoes in the parallel signals led to their respective outputs.

The separation circuit 7 consists of N windows associated with each output, which is positioned in time and whose lIg can be variable or constant. Each window of separation enclosure 7! ``located corresponding to the position of the echo according to the order of the echoes for the t1 working cycle.

The location of the echo in the reference signal relative to the excitation pulse delivered by transducer 1 is
The position of isopods changes slightly, and the total amplitude of the echoes changes with time depending on various physiological parameters.

Each output signal of the separation circuit 7 is connected to a respective filter 91-9N which integrates the respective pulse to provide a continuous curve representing the evolution of each pulse as a function of time.

The analog signal formed by each filter 91-9N is applied to an analog-to-digital converter 10 for conversion into a digital signal, the digital output of which can be processed by a digital processor 11,
The data may be sent to a cathode ray screen 12, a printer or plotter 13, or stored in a memory (not shown) for further processing.

Also, the development of the response signal at the output of the amplifier 3 by means of a cathode ray tube 15, a horizontal scan circuit 16 connected to a synchronization signal generator 4, a vertical scan amplifier 14 controlled by the output signal from the amplifier 3; It is also possible to monitor the cathode ray tube 15 which is also driven by.

Even though generally speaking, a single transducer 1 is sufficient for the medical device according to the present invention, for ease and speed of processing, the components of the medical device are mounted on heavy machinery, and the transducer 1 is A second transducer 1' is provided symmetrically to each part of the processing circuit, and also includes a pulse signal generator 2', an amplifier 3' for receiving the output signal from the first transducer 1, and a circuit 7 for deflecting the echo signal. ' and filters 91' to qNL2. High storm piezoelectric device 5, synchronization signal generator 4,
Gain correction circuit 6, cathode ray tube 5, horizontal scan circuit 16 and vertical scan circuit 14# can be shared as two subsystems of the medical device.

In the case of two transducers 1.1', it is sufficient to select an analog-to-digital converter 10 with a power number equal to the number of outputs of the separation circuits 7, 7'. On the output side of the output of this analog-to-digital converter 10, a processor 1) 11, a cathode ray screen 12,
Printer 13, peripherals, etc. can be shared with the two subsystems of the medical device, if desired.

The operation of the echo signal separation circuit is synchronized by a synchronization signal generator 4. Moreover, this circuit includes filters 91 to
9N.

OPERATION The operation of the medical device illustrated in FIG. 1 and the processing of the signals obtained by the device is illustrated in FIGS. 2A-2I/ and 5A-3B.

In each of Figures 2A-3B, the vertical axis represents voltage and the horizontal axis represents time.

FIG. 2A shows the total timing pulses provided by the synchronization signal generator 4 clock. This produces an excitation pulse for transducer 1 that corresponds to the curve of Figure 2B. Excitation pulses are also supplied to the transducer 1' as shown in FIG. 2B1. Shown here 1
．． In the embodiment shown, alternating timing pulses are associated with the operation of one transducer 1 and intermediate timing pulses are associated with the operation of transducer 1'.

FIG. 2C shows the transducer 1 in response to the pulse signal transmission.
A series of echo signals S, ,82. Sm
1. It shows Sm. This response (No. 8) consists of pulse trains corresponding to the various diopters encountered by the input pulse signal.

The response pulse streams correspond to each individual caballus in FIG. 2B.

FIG. 201 shows that the curve 2B+ has a qualitative difference between the pulse number 11d and the response number 11d.

A gain correction circuit 6ti controlled by the synchronization signal generator 4 controls the gain state of the amplifier 3 or amplifier 6' according to the curve shown in FIG. 2D. The Cain curve of FIG. 2D is repeated for each timing pulse obtained by generator 4, since the gain correction powder anticipates both the signal produced by transducer +F1 and the signal produced by transducer 1'. It will be done.

After correction and rectification of the gains of the amplifiers 3, 3', the echo signals shown in FIGS. 21, 2 and 1 are obtained.

A separation circuit 7 for echo signals, synchronized by a synchronization signal generator 4, generates at its respective output a respective repeating echo signal from the echo stream of FIG. 2E. Separation circuit 7
The respective signals appearing at each output are shown in Figure 2F, Figure 2G,
This is represented by the curves in FIGS. 2H and 21. During the corresponding intervals, isolation circuit 7' operates similarly to isolation circuit 7 and generates the signals shown in FIGS. 2y1, 2H1 and 2x1.

3A and 5B show, for example, the second
20 shows the evolution of the amplitude of a signal such as the signal corresponding to the output (FIG. 20). FIG. 3A shows the echo signal S2 (,) obtained during a certain number of consecutive cycles with the same transducer.

S21.・・・・・・・・・S27. This shows the series of A filter 92 associated with this signal integrates it and produces at its output the continuous signal shown in diagram i3B. Examination of this signal and comparison with a reference signal results in a medical conclusion to be reached.

Although the outline was discussed in the first part of this specification, it is possible to exclude physiological indices in the case of brain analysis. This index is a relevant function of the amplitude and of the morphology (frequency spectrum) of the local brain pulse curve.

Thus, on the basis of a 1 cm test area, the following pulse wave description index can be defined; The right side arterial pulse wave description index is calculated by the sum of the amplitudes of the pulses in the entire area of both hemispheres.

(Bl The left cortical pulse wave depiction index is limited by A above, except for the left cerebral hemisphere.

(C) The right cortical pulse wave description index is limited by the ratio of the sum of the amplitudes of pulses in all areas of both cerebral hemispheres to the amplitude of pulses in area 3 of the right cerebral hemisphere.

(Dl The left cortical pulse wave depiction index is C above except for the left cerebral hemisphere.
limited by.

(P2) The right superficial sylvian pulse wave description index is limited by the ratio of the sum of the amplitudes of the pulses in all areas of the two cerebral hemispheres to the 11th of the amplitudes of the pulses in areas 3, 4 and 5 of the right hemisphere. .

(Fl The left superficial Sylvian 1 water wave description index is limited by the upper dpiE, except for the right hemisphere.

This list of pulse wave descriptive indices is not exhaustive and fI
k'M fi bottom (vertebro-baeilia
r) #It can be derived by means similar to limiting the wave description index.

The present invention allows automatic calculation of pulse wave descriptive indices and their display or recording, providing complete compensation between changes in these indices and clinical observations not detailed here.

The present invention also enables OT to assess local blood flow velocity and measure intracranial pressure externally.

The device according to the invention also allows for the establishment of prognosis by investigating the response of blood vessels to stimuli, and also the direct glaciation of treatments such as drug therapy. This is especially important in the case of resurgence and intensive processing. Furthermore, this device is 4J! and can be placed closer to the patient than in many previous cases, where there was no need to move the patient.

The medical device according to the invention can also consist of a device for taking out internal pressure values in analog or digital representation and analog or digital means for determining values of local blood flow velocity.

Finally, the present invention is also effective in determining the state of brain death due to lack of cerebral blood circulation. As mentioned above, various tests are usually performed on the right or left cerebral hemisphere, the other being obtained by analogous analysis. An inventive embodiment comprising at least two transducers allows accurate simultaneous analysis of both halves of the brain. Simultaneous analysis of the two halves is performed by the conclusions drawn when comparing the signals.

Finally, the information stored by analyzing the echo currents produced in response to the excitation pulse is generally processed by very commonplace programs using small computers or more powerful equipment, for example for statistical purposes. can do.

Many changes may be made to the details, materials and parts of this specification which illustrate and disclose the invention without departing from the spirit and principles of the invention as set forth in the claims below. It would be possible for a person skilled in the art to add

[Brief explanation of drawings]

FIG. 1 is an overall block diagram of the medical device according to the invention. FIGS. 2A to 2I' show timing diagrams of each axis signal obtained by the apparatus shown in FIG. 1. It's an eargram. Figures 3A and 3B show the evolution of the echo signal as a function of time. The correspondence of main reference numerals in the figure is as follows. 1.1'...Transducer 2.2'...Pulse generator 3.3'...Amplifier 4...Synchronization signal generator 5...High voltage wt source circuit 6...Gain correction circuit 7.7'...Signal separation circuits 91 to 9N...Filter 10...Analog-digital converter 11...Processor 12...Cathode ray screen 13.1 Printer 14...Vertical scan amplifier 15. ...Cathode ray tube 16...Horizontal scan amplifier agent Mitsuyoshi Ezaki agent Prefumi Ezaki

Claims (1)

Claims: (1) at least one ultrasonic transducer table adapted for operation as a transceiver, connected to the output of the transducer, with a pulse generator adapted to direct a series of excitation pulses to the transducer; an amplifier having a gain that varies according to a predetermined law; and a circuit for separating a series of earth currents corresponding to the excitation waves delivered by the transducer and received by the transducer. A medical device 1 suitable for analyzing cerebral pulses from the cranial wall, comprising: a filter system having a plurality of P-wave channels; and a circuit for processing the obtained signal. The medical device according to claim 1 further comprises an automatic circulation circuit connected to the ih distribution circuit and a synchronized signal generator connected to the automatic circulation circuit, the arrangement of which is transmitted by the transducer. an excitation pulse generated by the transducer and amplifier to generate an echo stream that is directed into the parking circuit and automatically scanned to separate echoes corresponding to each cranial layer to be examined. (31) The medical device according to claim 1, wherein the processing circuit comprises an analog-to-digital converter connected to the output of the F-wave channel of the filter system;
and means adapted for directing the final digital signal to a processor-controlled display device and/or printer. (4) In the medical device according to claim 2, =1+1 cloud 1 I@★ff1lffl 路 7 り 5 - 1 waterfall = pole - 5 6F no-in contribution FIffM month signal a horizontal scan circuit connected to the generator, and before-
a vertical scan circuit connected to the transducer via a writing width transducer. (5) A medical device according to claim 1, formed as a parallel connection of at least two parts each consisting of a transducer, an amplifier, a separation circuit and a filter system, and two simultaneous Something that can be analyzed. (6) % Allowance The medical device according to claim 1, comprising means suitable for obtaining an analog or digital display of the pressure inside the lid. (7) A medical device according to claim 1, comprising suitable means for obtaining an analog or digital display of local blood flow velocity.