JPH06335478A - Ultrasonic diagnostic device with measurement function - Google Patents

Abstract

PURPOSE:To measure the distance between specified portions in the organism with higher accuracy by processing output signals of a signal reception delay line by each signal to arrange according to the order of arrayed oscillators and by measuring the distance between specified portions according to the waveform of the reflected echoes to convert the value into a conversion distance in the organism. CONSTITUTION:In the measurement of the diameter of a blood vessel 10, etc., a drive waveform is applied to plural arrayed oscillators 11 via a signal transfer delay line 12, the waveform are generated from the oscillators 11, and reflected pulse waves that are reflected at a blood vessel 10 are received by the oscillators 11. The electric signals are input to an adder 14 via a signal reception delay line 13 to create one-line reflection signals, and the output of each signal reception delay line is input to a multi signal processing circuit 20 to be processed with a logarithmic compression, detection, STC, etc., and stored in a buffer memory 22. At DSC 23, signals that have been brilliance-modulated to specified positions of the ultrasonic image are displayed according to the order of the arrayed oscillators 11, the distance between specified two portions is measured using the electronic caliper function, and the value is converted into a conversion distance in the organism.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic diagnostic apparatus with a measuring function.

[0002]

2. Description of the Related Art FIG. 4 is a conceptual diagram showing the construction of a conventional ultrasonic diagnostic apparatus. The sync signal output from the sync controller 1 enters the digital variable delay pulse generator 2. From the digital variable delay pulse generator 2, pulses whose phases are gradually shifted are generated. This pulse is generated by the high frequency pulse oscillator 3
The probe 4 is driven via. The probe 4 is a probe for scanning an electronic sector, is composed of a plurality of transducers, and is driven by a pulse having a slightly different phase between adjacent transducers.

The high frequency pulse from the probe 4 is the subject 5
It is emitted toward. Reflected signals from the subject 5 are received by the same transducer, delayed by the analog variable delay & adder 5, and added. The output of the analog variable delay & adder 5 enters a receiver 6, is A / D converted and converted into digital data, and then enters a digital scan converter (DSC) 7. The digital scan converter 7 performs conversion in the scan direction in order to display the signal of the subject 5 received by the probe 4 on the television. The sync signal from the sync controller 1 is input to the digital scan converter 7, and the read image information is output to the diagnostic device monitor 8. An image of the subject 5 is displayed on the diagnostic device monitor 8 in synchronization with the scan.

Next, let us consider a case where the diameter of a blood vessel or the like is measured using such an ultrasonic diagnostic apparatus. FIG. 5 is an explanatory diagram of conventional blood vessel diameter measurement. When measuring the diameter of the blood vessel 10 or the like, a drive waveform is applied to the array transducer 11 through the transmission delay line 12. The array transducer 11 is composed of 2N + 1 transducers from 1 to N and -1 to -N with the transducer at the 0 position as the center.

Then, a focused ultrasonic pulse is emitted from the array transducer 11, the reflected pulse waveform from the blood vessel 10 is received by the array transducer 11, and converted into an electric signal. This electric signal waveform is added by the adder 14 through the receiving delay line 13. This one series of reflected signals is subjected to signal processing such as logarithmic amplification, detection, digital scan converter (DSC),
Display on the diagnostic device monitor.

Also when displaying on a diagnostic device monitor, A mode for displaying one series of signals like an oscilloscope,
There are an M mode in which one series of signals is brightness-modulated and displayed in a linear shape based on brightness, and a B mode display in which the array vibrator 11 is scanned and displayed in a cross-sectional shape.

[0007] Generally, the blood vessel diameter is measured by measuring the t _INT time as shown in the figure from the output signal of the adder 14 or the envelope signal subjected to the amplification / detection processing, and the blood vessel diameter is obtained from the following equation. However, C is the average sound velocity in the living body.

2a = C · t _INT / 2 (1) This value is the in vivo equivalent distance. In this way, the obtained blood vessel diameter contains an essential error. The method of calculating this error will be described below.

FIG. 6 is an explanatory diagram for calculating an error when measuring a blood vessel diameter. Consider a case where the electron focusing point of the array transducer 11 is set to the zf point. In this case, the focal point is set inside the blood vessel 10. Further, for simplification of description, the ultrasonic beam transmitted and received from each array transducer 11 is represented by a straight line.

The diameter of the blood vessel is 2a, and electron focusing is performed at the center thereof. Further, the pitch of the piezoelectric elements (array transducers) 11 of the array type probe is p. The explanation is simplified by setting the number of array elements to be an odd number, which is axisymmetric. Further, a number is assigned to the array transducer 11, the array element located at the center as shown in the figure is numbered 0, and as it goes up, it is numbered 1, 2, ...
The maximum number is N. Similarly, in the downward direction from 0, the numbers are -1, -2, ... And the maximum number is -N.

Further, an arbitrary number of the array element is represented by the number n, and the array element numbers are added as subscripts to the distances associated with these array elements to distinguish them. The reference delay amount of electron focusing is set to the Nth position of the array element.
When the radius of curvature of electron focusing is R, R = zf · x _N , R
= Zf · x _−N .

[0012] Request zf and distance between x0 (hereinafter referred to as _{zf · x 0), zf ·} x 0 is expressed by the following equation.

[0013]

[Equation 1]

[0014] Next, the distance zf · _{x n} is expressed by the following equation.

[0015]

[Equation 2]

Next, the distance zf · F _n is expressed by the following equation.

[0017]

[Equation 3]

Next, the distance x _n · C _n is expressed by the following equation.

[0019]

[Equation 4]

Next, an ultrasonic focusing pulse is received from the n-th array transducer, and the focused ultrasonic pulse is F on the front wall of the blood vessel.
The distance until the light is reflected at the _n point and returns to the nth array transducer is obtained. The transmission / reception electron focusing delay amount is the time required for the ultrasonic wave to propagate the distance x _n · C _n .

Now, the ultrasonic wave is transmitted from the n-th array transducer located at the virtual position C _n , the ultrasonic pulse is reflected at the position F _{n on the} front wall of the blood vessel, and the ultrasonic pulse is generated at the virtual position C _{n. It} may be considered that the wave is received by the n-th array transducer located at n.

The path length r _Fn through which the ultrasonic wave has been transmitted from the n-th array transducer to the wave reflected from the anterior wall of the blood vessel and received is expressed by the following equation.

[0023]

[Equation 5]

Similarly, the path length r _Bn through which the ultrasonic waves are transmitted by the n-th array transducer, reflected by the rear wall of the blood vessel, and received is expressed by the following equation.

[0025]

[Equation 6]

Here, Df is the distance zf · x ₀ from the 0th position of the array transducer to its focusing point zf, and is represented by the following equation, similar to equation (2).

[0027]

[Equation 7]

Next, the arrival time of the reflection echo from the blood vessel wall in the conventional ultrasonic diagnostic apparatus will be examined. The time t _Fn from when the nth array transducer transmits and is reflected by the front wall of the blood vessel until it is received by the nth array transducer is
It is expressed by the following equation, where C is the average sound velocity in the living tissue.

[0029]

[Equation 8]

Here, the maximum and minimum of the time t _Fn are obtained. That is, it is nothing but the time to reach the array transducer first and the time to reach the array transducer last. When n = 0,
It will be the maximum. That is, it means that the reflected echo is input lastly to the input of the adder connected to the 0th array transducer. The maximum value of the time t _Fn is expressed by the following equation.

[0031]

[Equation 9]

When n = N, -N, the minimum value is obtained.
That is, it means that the reflected echo is input first to the input of the adder connected to the Nth and -Nth array transducers. The minimum value of the time t _Fn is expressed by the following equation.

[0033]

[Equation 10]

Next, the wave is transmitted from the n-th array transducer,
The time t _Bn from the time when the light is reflected by the posterior wall of the blood vessel to the time when it is received by the n-th array transducer is calculated by the following equation.

[0035]

[Equation 11]

The maximum and minimum of the time t _Bn thus obtained are obtained. Similarly, from the equation (12), the maximum value is obtained when n = N, −N, and the maximum value is expressed by the following equation.

[0037]

[Equation 12]

When n = 0, the minimum value is obtained, and the minimum value is expressed by the following equation.

[0039]

[Equation 13]

As described above, in the conventional ultrasonic diagnostic apparatus, the ultrasonic echo received by each array transducer is
After being added by the adder, it is displayed as one sound source.
This is illustrated in FIG. 7. The shaded area in the figure shows the wave front of the signal input to the adder of each array transducer.
The crests indicate that they have the width of the shaded area. In addition, the transmitted ultrasonic pulse has a finite pulse width PW.
Since, in fact, MAX [t _Fn ] and MAX
The signal exists by the pulse width after [t _Bn ].

Therefore, in order to measure the distance between the front wall of the blood vessel and the rear wall of the blood vessel, even if the distance between the front wall of the blood vessel and the rear wall of the blood vessel is measured by the conventional ultrasonic diagnostic apparatus, the displayed bright line The error is already included in. In general measurement, MAX
The time difference between [t _Fn ] and MIN [t _Bn ] is measured, and this is converted into a distance to obtain the blood vessel diameter. Therefore, at a minimum

[0042]

[Equation 14]

The error of is included in the blood vessel diameter. This error is an error that is inevitably included when measuring the wall interval of a blood vessel or the like with a conventional ultrasonic diagnostic apparatus. FIG. 8 is an explanatory diagram of the measurement error of the blood vessel diameter. (A) is a received waveform signal obtained by a conventional ultrasonic diagnostic apparatus, which is an output signal of an adder. This output signal is obtained by adding the received waveform signals from each array transducer (see (b)) on the time axis,
The time is the time at which the wave fronts of the -N and N-th array transducers are detected.

The time is the time at which the crest of the reflected pulse from the front wall of the blood vessel is detected by the 0th array transducer.
The time and section are pulse widths. All wave fronts enter the time and section, and cannot be separated from each other. The same applies to the waveform from the posterior wall of the blood vessel. Therefore, in the conventional ultrasonic diagnostic apparatus, the blood vessel diameter is obtained by measuring time and time.

Next, consider a waveform which is transmitted from the array transducer 11, is reflected by a tubular reflector such as a blood vessel, and is received by each array transducer in the apparatus as shown in FIG. Since the waveform is generally considered, it is represented by a wave front and a pulse width. Further, the actual behavior of the waveform is caused by a complicated physical phenomenon such as interference and diffraction, which makes it difficult to explain the general principle. Here, the principle is simplified with the concept of sound rays. In addition, here, the case where the tubular reflector is present in front of the focus of electron focusing will be considered. That is, this is the case where the focus of electron focusing is outside the blood vessel 10.

The diameter of the blood vessel 10 is 2a, and the array oscillator 11
The pitch of is p. The formula is simplified by setting the number of array elements to be an odd number with axial symmetry. Assign a number to the array transducer,
The allocation is the same as in FIG. The distance zf · x ₀ is expressed by the following equation.

[0047]

[Equation 15]

Next, when the distance zf · x _n is obtained, it is expressed by the following equation.

[0049]

[Equation 16]

Next, when the distance zf · F _n is calculated, it is expressed by the following equation.

[0051]

[Equation 17]

Next, when the distance zf · B _n is calculated, it is expressed by the following equation.

[0053]

[Equation 18]

Next, when the distance x _n C _n is calculated, it is expressed by the following equation.

[0055]

[Formula 19]

Next, the ultrasonic pulse focused by the electron-transmitting delay for wave transmission from the n-th array transducer is reflected at the point F _{n on the} front wall of the blood vessel and received by the n-th array transducer. Then, when the equivalent distance r _Fn to the input of the adder is obtained by receiving the receiving electron focusing delay, it is expressed by the following equation.

[0057]

[Equation 20]

Next, an ultrasonic focusing pulse is received from the n-th array transducer and the focused ultrasonic pulse is transmitted to the blood vessel B of the posterior wall.
It is reflected at the n point and received by the nth array transducer,
When the equivalent distance r _Bn to the input of the adder is obtained by receiving the electron focusing delay for reception, it is expressed by the following equation.

[0059]

[Equation 21]

Next, the time t _Fn from the time when the n-th array element transmits the wave and the wave is reflected by the anterior wall of the blood vessel until it is received by the n-th array element is determined. Here, C is the average sound velocity in the living tissue. t _Fn is expressed by the following equation.

[0061]

[Equation 22]

Next, the maximum and minimum of t _Fn are obtained. t _Fn becomes maximum when n = 0, and the maximum value is expressed by the following equation.

[0063]

[Equation 23]

T _Fn becomes minimum when n = N, -N, and the minimum value is expressed by the following equation.

[0065]

[Equation 24]

Next, the time t _Bn from the time when the n-th array transducer transmits and is reflected by the posterior wall of the blood vessel until it is received by the n-th array transducer is calculated, It

[0067]

[Equation 25]

Next, the maximum and minimum of t _Bn are obtained. t _Bn becomes maximum when n = 0, and the maximum value is expressed by the following equation.

[0069]

[Equation 26]

T _Bn becomes minimum when n = N, -N, and the minimum value is expressed by the following equation.

[0071]

[Equation 27]

When these are arranged on the time axis, it becomes as shown in FIG. In general measurement, MIN [t _Fn ] and MIN [t
_Bn ] time difference is calculated, and it is converted into the in-vivo conversion distance. At this time, the error of the blood vessel diameter is expressed by the following equation.

[0073]

[Equation 28]

As is clear from a comparison between the equations (29) and (15), the object to be measured is set closer to the probe than the electron focusing point when the electron focusing point zf is set in the center of the blood vessel. The method has a large error.

[0075]

As described above, the conventional measuring method has a problem that an error is essentially included when measuring the distance of a specific portion in the living body. The present invention has been made in view of such problems, and an object thereof is to provide an ultrasonic diagnostic apparatus with a measuring function that can accurately measure the distance of a specific portion in a living body.

[0076]

According to the present invention for solving the above-mentioned problems, the output signals of the receiving delay line are processed independently for each signal and arranged in the order of array transducers, and the reflection echoes thereof are arranged. 2 of the specific part from the ripple shape of the
The feature is that the distance between the points is measured and converted into the in-vivo converted distance, and the distance of a specific portion in the living body is measured.

[0077]

When measuring the distance of a specific part in the living body by the conventional device, the measurement error occurs because the outputs of the array transducers are added by the adder. Focusing on this point, the present invention independently processes the outputs of the array transducers and arranges them in the order of the array transducers, and measures the ripple shape of the reflected echo between two points of a specific portion by using the electronic caliper function. Then, the distance is converted into the in-vivo converted distance, and the distance of a specific portion in the living body is measured. Therefore, it is possible to accurately measure the distance of the specific portion in the living body.

[0078]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a configuration block diagram showing a main part of an embodiment of the present invention. The same parts as those in FIG. 5 are designated by the same reference numerals. In the figure, 10 is a blood vessel as a specific part of a biological tissue, 11 is an array transducer for wave transmission, 12 is a delay line for wave transmission, 13 is a delay line for wave reception, and 14 is an addition for obtaining an ultrasonic echo signal. It is a vessel.

Reference numeral 20 denotes l for the output of each receiving delay line.
A multi-signal processing circuit for performing og compression, detection, STC processing, etc., 21 is an A / D converter for converting the output of each delay line processed by the multi-signal processing circuit 20 into digital data, and 22 is an A / D converter. 21 is a buffer memory for storing output data of each delay line according to the reference numeral 21. Reference numeral 23 is a digital scan converter (DSC) that converts the scanning direction of the image data for display on the diagnostic device monitor. The output of the buffer memory 22 is input to the digital scan converter 23. Reference numeral 30 is a system control for performing read / write control of the buffer memory 22 and read / write control of the digital scan converter 23. The DSC 23 is also desired to be provided in the conventional device. The part surrounded by the broken line in the figure is the part that characterizes the present invention. The operation of the apparatus configured as described above will be described below.

The respective reception delay line outputs from the preceding stage of the adder 14 of the conventional ultrasonic diagnostic apparatus are put into the multi-signal processing circuit 20 and subjected to processing such as logarithmic compression, detection and STC processing. The output of each delay line processed is A / D
It enters the converter 21 and is converted into digital data. A /
The output of the D converter 21 is a buffer memory (line memory)
22 is stored.

The system control 30 sends the contents of the buffer memory 22 to the digital scan converter 23. Then, the specific X of this digital memory for image is
The data recorded in the buffer 22 is written in the Y coordinate.
Thereby, the signal whose brightness is modulated at a specific position of the ultrasonic image can be displayed in correspondence with the order of the array transducer 11. For example, the region of interest to be measured is obtained from the B-mode image, and only the region of interest is displayed by the above method.

FIG. 2 is a diagram showing an example of a diagnostic device monitor screen according to the present invention. IM1 is a conventional B-mode diagnostic image, and IM2 is a diagnostic image of a specific portion according to the present invention. According to the present invention, the measurement target area is set in the B mode.
The signal waveforms from the array transducers 11 forming the bright line (the output signal of the adder 14) forming the image of this ROI and further forming the bright line are displayed in the order of the array elements like IM2.

In contrast to this figure, the electronic caliper function widely used in the conventional ultrasonic diagnostic apparatus is used, and a pair of cursors that can be moved on the display screen is used to calculate the in vivo equivalent distance of a specific ripple section. taking measurement.

FIG. 3 is a diagram schematically showing a general ripple pattern. FIG. 7A shows a case where the electronic focusing point zf is set on the rear side of the blood vessel 10, and FIG. 9B shows a case where the electronic focusing point zf is set inside the blood vessel of the blood vessel 10, for example, in the center of the blood vessel. The case where the electronic focusing point zf is set on the front side of the blood vessel 10 is shown.

The upper curve in each figure shows the wave front locus of each receiving delay line output, and the lower curve shows the wave tail locus of the same output signal. In such an arrangement, time T
When the time in the section between A and TB is measured with an electronic caliper and the converted distance in the living body is obtained, the error caused by the addition is reduced to the theoretical limit, and the distance (here, the blood vessel diameter) of a specific portion of the living body is calculated. Can be measured accurately.

Further, the present invention has the following effects. That is, the substantial position of the electron focusing point can be visualized in vivo from this ripple shape. Conventionally, the amount of delay for wave transmission, the amount of delay for wave reception, etc. are determined at the design stage, and a confirmation experiment is conducted in a water tank or the like to set the electron focusing point. However, it has been qualitatively confirmed in the B mode whether or not the light is focused on a predetermined focus point in the actual living body.

However, if there is a site or tissue or a scatterer that has a reflection coefficient somewhat larger than that of the surroundings, which already exists in the living body,
The focus point can be measured in vivo from this ripple shape. That is, when ripples (a) to (c) are continuously arranged from the probe side, in the case of (b), the straight lines on the right and left sides of the curve are near the focusing point, especially at the location of the focusing point. The depth of this straight line is the focal point, and the actual position in the living body can be visualized and measured.

In the above-mentioned embodiment, the case where the blood vessel diameter is measured for measuring a part of the living body is taken as an example, but the present invention is not limited to this. For example, it is possible to measure the distance between a portion having a large reflection coefficient, tissue, and other tissue such as a scatterer.

[0089]

As described above in detail, according to the present invention, it is possible to provide an ultrasonic diagnostic apparatus with a measuring function capable of accurately measuring the distance of a specific portion in a living body.

[Brief description of drawings]

FIG. 1 is a configuration block diagram showing a main part of an embodiment of the present invention.

FIG. 2 is a diagram showing an example of a diagnostic device monitor screen according to the present invention.

FIG. 3 is a diagram showing a general ripple pattern.

FIG. 4 is a conceptual diagram of a configuration of a conventional device.

FIG. 5 is an explanatory diagram of conventional blood vessel diameter measurement.

FIG. 6 is an explanatory diagram of error calculation when measuring a blood vessel diameter.

FIG. 7 is a diagram showing a variable range of times t _Fn and t _Bn on the time axis.

FIG. 8 is an explanatory diagram of measurement error of blood vessel diameter.

FIG. 9 is an explanatory diagram of error calculation when measuring a blood vessel diameter.

FIG. 10 is a diagram showing a variable range of times t _Fn and t _Bn on the time axis.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Blood vessel 11 Array transducer 12 Delay line for transmission 13 Delay line for reception 14 Adder 20 Multi-signal processing circuit 21 A / D converter 22 Buffer memory 23 Digital scan converter 30 System control

Claims (2)

[Claims] 1. An output signal of a wave receiving delay line is processed independently for each signal and arranged in the order of array transducers, and the ripples of the reflected echoes are used to determine a specific portion of the two signals using an electronic caliper function. An ultrasonic diagnostic apparatus with a measuring function, characterized in that the distance between points is measured and converted into an in-vivo equivalent distance to measure the distance of a specific portion in the living body. 2. The ultrasonic wave with a measuring function according to claim 1, further comprising a function capable of measuring and visualizing an actual focusing point in the living body from the ripple shape of the reflection echo obtained by the processing. Diagnostic device.