JPH09313486A - Ultrasonic biological measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To display an image to indicate the spatial distribution of the slack/ contract characteristics of a myocardial fiber of a heart wall and the temporal change of the characteristics by evaluating the characteristics non-invasively for each local area. SOLUTION: From the reflected waves of ultrasonic pulses transmitted to a heart wall, the displacement motion waveform and velocity waveform are measured for each of a plurality of points apart in a minute distance within the heart wall, and the parallel displacement motion of the heart wall is canceled from the difference in the displacement motion waveform and also difference in the velocity waveform between the two points. The thickness of each local myocardium and the velocity of thickness change are determined, and the elongation and contraction components of the myocardium are colored in blue and red, respectively, and the spatial distribution of the slack/contract characteristics and the temporal change of the myocardial fiber are indicated by color images by overlapping the M-mode image on the B-mode image.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diagnostic apparatus for evaluating local relaxation contraction characteristics of myocardium.

[0002]

2. Description of the Related Art Conventionally, as an image display method in an ultrasonic diagnostic apparatus, there are M mode display, B mode display, color Doppler display and tissue Doppler display.

In the M mode display, the ultrasonic pulse repeatedly propagated into the living body from the ultrasonic probe is reflected at a position where there is a difference in acoustic impedance in the living body and returns to the ultrasonic probe again. Brightness modulation (converting the amplitude of the reflected wave into a change in brightness), the time until the reflected wave returns (depth of each reflection point) is the vertical axis of the cathode ray tube, and the repetition time of the transmission pulse is the cathode ray tube. The image is displayed on the horizontal axis of. Since the depth of the reflected echo from the moving echo source changes with time, the depth corresponding to the movement is displayed, and the temporal change of the moving echo can be observed.

In the M mode display, the ultrasonic pulse is always transmitted in the same direction and the reflected echo in that direction is displayed. In the B mode display, however, the ultrasonic pulse is transmitted and received once and the reflected waveform is radiated. After modulating and displaying on the screen,
Change the direction of the ultrasonic beam, send and receive again, and display the results on the screen. At this time, the display position of the bright line on the screen is moved according to the moving direction and moving distance of the ultrasonic beam. By repeating this, it is possible to obtain the position and shape of the living body organ as the echo source as a tomographic image.

In the B mode display, the amplitude of the reflected waveform is brightness-modulated and displayed to obtain a tomographic image of the boundary of the acoustic impedance. In the color Doppler display, each point is based on the reflected wave from each point of the echo source. By calculating the blood flow velocity of the blood flow and displaying the spatial distribution of the blood flow velocity on the tomographic image, an abnormality such as reverse flow of blood flow in the heart or artery can be detected.

Although the blood flow velocity at each point of the echo source obtained by color Doppler display is high, the amplitude of the reflected wave itself is very small, so that the color Doppler display device can detect only these high-speed components. As such, a high pass filter is used. On the other hand, since the velocity of motion of tissues such as myocardium is slower than the velocity of blood flow, by replacing the above high-pass filter with a low-pass filter, the spatial distribution of the velocity at each point in the tissue is shown as a tomographic image. Can be displayed on top of each other. This is the principle of tissue Doppler display.

[0007]

Consider a displacement waveform and a velocity waveform at a plurality of points on a line perpendicular to the wall surface on the tomographic image of the heart. The motion of each of these points in the heart wall includes a low-frequency, large-amplitude vibration component caused by pulsation, valve opening / closing, and blood inflow, and a motion component caused by relaxation contraction of the myocardium inside the heart wall. The former vibration component represents a translational motion in phase at each point in the wall. On the other hand, the latter motion component corresponds to the change in thickness based on the temporal change in the velocity difference at each point in the myocardium. If the relaxation and contraction characteristics of each local part of the myocardial fiber can be measured, it will be a medically important diagnostic method. However, in conventional methods and diagnostic devices, it is impossible to non-invasively measure the relaxation contraction property, and an ultrasonic wave that can display the spatial distribution of the relaxation contraction property of myocardial fiber and its temporal change. Development of a diagnostic device is desired.

[0008]

According to the present invention, the time integration of the difference in velocity between two points in the heart wall is the difference in displacement between the two points, that is, the change in thickness between the two points.
By utilizing the fact that the difference in velocity between points expresses the velocity of thickness change, the relaxation and contraction characteristics of myocardial fibers for each local myocardium are quantitatively evaluated, and the instantaneous elongation component and shrinkage obtained for each local myocardium are further evaluated. By displaying the components in color and superimposing them on the M-mode image and the B-mode image obtained by the ultrasonic diagnostic apparatus, the spatial distribution and temporal change of the relaxation contraction property of the myocardial fiber are provided as a two-dimensional image. First, in order to measure the displacement motion and velocity of each point of the myocardium in the heart wall as a waveform, the displacement of each point is tracked. Therefore, an ultrasonic pulse is repeatedly transmitted to the heart wall at intervals of ΔT, and ΔT relating to the propagation delay time of the reflected wave returning from one point of interest (called point i) in the ventricle wall.
The instantaneous velocity at that one point is calculated from the change within the time. This is based on the conventional ultrasonic pulse Doppler method, but further, by multiplying the instantaneous speed obtained now by ΔT,
The displacement of the point of interest within ΔT time is obtained, and the position of the point of interest is virtually moved by the displacement. The velocity calculation relating to the ultrasonic pulse to be transmitted next is performed using the reflection waveform at the timing when the ultrasonic pulse returns from the new position that has been reset. By repeating this process, even if the initially set position of the target point is displaced due to a large-amplitude beat, the position is tracked, and the displacement waveform x (i; t) and velocity of the target point are tracked. The waveform v (i; t) can be calculated. Further, a large number (N pieces) of the points of interest i are set on one ultrasonic beam at Δx intervals, and displacement waveforms x (i; t), i = 1, 2 ,. . , N and velocity waveform v
(I; t), i = 1, 2 ,. . , N is calculated.

Displacement waveform x of each point calculated here
(I; t), i = 1, 2 ,. . , N and velocity waveform v (i;
t), i = 1, 2 ,. . , N contains two components, a translational motion component and a thickness change component due to relaxation contraction motion of the internal myocardium. In the former, the waveforms at all points are included in the same phase, so the translational motion component of the former is canceled by obtaining the difference between the displacement waveform and the velocity waveform obtained at the adjacent points i and i + 1. However, only the component of the thickness change can be calculated. That is, the difference between displacement waveforms x (i; t) -x (i +
1; t), the change in thickness h (i; t) between the point i and the point i + 1 set in the heart wall is calculated, and the difference in velocity waveform v
From (i; t) -v (i + 1; t), the rate of thickness change Δh (i; t) between the point i and the point i + 1 set in the heart wall can be calculated.

The rate of change in thickness Δh (i;
Considering the case where the myocardium in the heart wall is uniformly relaxing and contracting, t) is the interval Δx set at the beginning between the two points i and i + 1.
Is narrower, and Δx is larger, and therefore depends on the interval between the two points. The speed Δh (i; t) of the thickness change thus obtained is set to the initially set thickness Δx.
The thickness is normalized by using Δh (i; t) / Δx obtained by dividing by
A rate of thickness change independent of x is obtained.

The above process is applied to each point set every several hundreds of microns (Δx) in the heart wall myocardium to change the thickness of the local myocardium in units of several hundreds of microns and the space of the velocity of the thickness change. Calculate the distribution.

The velocity of the change in thickness of the local myocardium thus obtained is colored according to a predetermined color code for each region according to the positive and negative values and their magnitudes,
By superimposing and displaying the conventional M-mode image and B-mode tomographic image, the spatial distribution of relaxation contractility of the myocardium and its temporal change can be known.

[0013]

By combining the present invention with an ultrasonic diagnostic apparatus, it is possible to quantitatively evaluate the spatial distribution and temporal change of the relaxation contraction characteristic of the myocardial fiber for each local myocardium, and it becomes possible to perform non-invasive diagnosis of heart disease.

[0014]

EXAMPLES Examples of applying the present invention to a human heart wall will be described below. FIG. 2 shows an ultrasonic tomographic image of the left ventricle and septal wall of the ventricle of a healthy man in his 20s. The ultrasonic beam beam is fixed so as to enter the interventricular septum IVS between the left ventricle LV and the right ventricle RV of FIG. 2 almost vertically. Fourteen points are set at 0.75 mm intervals between the point R on the right ventricle RV side boundary on the ultrasonic beam and the point L on the left ventricle LV side.

FIG. 1 shows the measurement results of displacement waveforms and velocity waveforms on 14 points set at 0.75 mm intervals between points R and L shown in FIG. Waveform (a) in Figure 1
Is an electrocardiogram. The waveform (b) in FIG. 1 is a heart sound waveform.
FIG. 1C is an M mode diagram created from the amplitude of the reflected wave. The left edges (R) and (L) of FIG. 1C correspond to the depths of the points R and L of FIG.

The 14 white lines in the diagram of FIG. 1 (d) are set at 0.75 mm intervals between the points R and L 14
The displacement waveform x (i; t) obtained for each point is shown, and is displayed in a form of being superimposed on the M-mode diagram of FIG. 1 (c). Regarding these displacement waveforms, the difference between the displacement waveform x (1; t) at the point R on the right ventricular RV boundary line and the displacement waveform x (i; t) at the other 13 points set in the septal wall of the ventricle. The result of obtaining x (i; t) -x (i + 1; t) is shown in (f) of FIG. This means that at time 0, 0.
The temporal displacements of the 14 points set at 75 mm intervals are displayed as the relative distance (thickness) from the point on the right ventricle side. It can be seen that the thickness at the timing of the R wave of the electrocardiographic waveform (a) in FIG. 1 is increased by about 3 mm in the subsequent systole (around 0.5 seconds).

FIG. 1E shows the velocity waveforms v (i; t) at each point represented by the 14 white lines in FIG. 1D for all 14 points. The thicker line during systole (around 0.5 seconds) indicates that there is a velocity difference between the 14 points, indicating that there is a change in thickness within the heart wall. There is. On the other hand, in the diastole (around 1 second), the 14 lines are almost coincident with each other, showing that there is no difference in speed and no change in thickness.

FIG. 1 (d) shows a speed change Δh of the thickness change which is a speed difference between adjacent points with respect to the speed waveforms of 14 points.
(I; t) = v (i; t) -v (i + 1; t) is a result in which the speed of the thickness change normalized by dividing the initially set point interval of 0.75 mm is displayed in color. In this embodiment,
The color changes from blue to light blue as the speed of thickening increases, and from red to yellow as the speed of thinning increases, and the temporal change in local thickness associated with relaxation contraction inside the septal myocardium is approximately the cardiac cycle. Shown for one beat.

Although FIG. 1 was for a healthy man in his twenties, for comparison, FIG. 3 shows the results obtained in the same manner as in FIG. 1 for a patient with severe cardiomyopathy. The waveform of the difference between the displacement waveforms of FIG. 3 (f) shows almost no change between systole and diastole, and the systole has a thickness of only about 400 μm. That is, it can be seen that there is almost only a translational motion component. Therefore, the 14 velocity waveforms of waveform (e) in FIG. 3 almost overlap. Also, FIG.
Regarding the coloring result of (d) regarding the temporal change of the local thickness inside the myocardium, it can be seen that there is no uniform thickness change of the entire myocardium during the systole and the diastole. In this example, the relaxation contraction of the myocardium is no longer sufficient, indicating that the heart is not functioning well.

[0020]

As described above, the ultrasonic living body measuring apparatus of the present invention uses ultrasonic waves to non-invasively detect displacement motion waveforms and velocity waveforms at a plurality of points separated by a minute distance in the heart wall. The difference between the displacement motion waveform and the velocity waveform difference at the two points separated by the minute distance is calculated, and the translational motion component of the heart wall is canceled to sandwich the two points separated by the minute distance. For each local myocardium, the thickness and rate of change of the thickness are calculated, and the relaxation contraction characteristics of the myocardial fibers obtained for each local myocardium sandwiched by two points separated by a minute distance Then, the instantaneous elongation component and the contraction component are colored in blue and red, respectively, and are superimposed on the M-mode image and the B-mode image obtained by the ultrasonic diagnostic apparatus to obtain a spatial distribution of relaxation contraction characteristics of myocardial fibers. Displaying time-varying color images Therefore, it is made possible to quantitatively evaluate the relaxation shrinkage characteristics of cardiac muscle fibers of each essential regional myocardial necessary for the diagnosis of heart disease.

[Brief description of drawings]

FIG. 1 is a result of applying the present invention to a normal person.

FIG. 2 is a diagram showing an ultrasonic tomographic image in the vicinity of the septal wall of the ventricle.

FIG. 3 is a result of applying the present invention to a patient with severe cardiomyopathy.

[Explanation of symbols]

 ─────────────────────────────────────────────────── --- Continuation of the front page (72) Inventor Yoshiro Koiwa, 31 Sanjuto-cho, Aoba-ku, Sendai-shi, Miyagi (72) Inventor Motonao Tanaka 4-4-2, Kunimi, Aoba-ku, Sendai-shi, Miyagi

Claims (2)

[Claims] 1. An ultrasonic pulse is repeatedly transmitted to the heart wall, and a plurality of ultrasonic waves are separated by a minute distance along the ultrasonic beam in the heart wall from changes in the propagation delay time of a reflected wave returning from the heart image wall. Displacement motion waveforms and velocity waveforms are measured for each point, and the translational motion component of the heart wall is canceled by calculating the difference between the displacement motion waveforms and the velocity waveform difference at the two points separated by a minute distance, To quantitatively evaluate the relaxation contraction property of the myocardial fiber for each local myocardium by obtaining the thickness change and the speed of the thickness change occurring inside each local myocardium sandwiched by two points separated by the minute distance. An ultrasonic diagnostic apparatus for heart diseases. 2. The instantaneous elongation component of the thickness of the myocardial fiber obtained for each local myocardium sandwiched by two points separated by a minute distance along the ultrasonic beam within the heart wall is represented by a blue component and a contraction component. A heart characterized by displaying a color distribution of the spatial distribution and temporal change of the relaxation contraction property of myocardial fiber by superimposing it on the M-mode image and the B-mode image obtained by an ultrasonic diagnostic apparatus by coloring with a reddish color Ultrasound diagnostic equipment for diseases.