JPH1199152A - Ultrasonograph - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultrasonograph to operate under a condition suitable for picking up an image by injecting a contrast medium into a subject. SOLUTION: A transmission frequency and transmission sound pressure most adapted to a contrast medium are automatically set (D3 and D4). An image pickup space is automatically set (D7) so as to leave a space in which the contrast medium is sufficiently filled. An ordinary B mode image is displayed, but when a switch is pushed at desired time, only when its switch is pushed, a harmonic B mode image is displayed (D11). Even if operation is not performed at all, the ordinary B mode image and the harmonic B mode image are automatically renewed in time sharing (D12). The transmission frequency can be optimized so as to be most adapted to the contrast medium. The image pickup space can be optimized so as to leave a space in which the contrast medium is sufficiently filled. The ordinary B mode image and the harmonic M mode image can be substantially simultaneously can be seen.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an ultrasonic diagnostic apparatus, and more particularly, to an ultrasonic diagnostic apparatus which operates under conditions suitable for injecting a contrast medium into a subject and imaging.

[0002]

2. Description of the Related Art Air bubbles are injected into a subject as a contrast agent,
There is known a technique (harmonic B mode) for obtaining a signal component having a frequency twice as high as the transmission frequency from among the signal components of the ultrasonic echo and generating a signal strength image thereof.

[0003]

Since the size and density of bubbles as a contrast agent differ depending on the type of the contrast agent, it is considered that the transmission frequency and sound pressure that are most matched differ depending on the type of the contrast agent. Technology to optimize sound pressure
Conventionally, not known.

In the case where bubbles as a contrast agent are destroyed by the sound pressure of an ultrasonic beam, contrast is obtained even when images are continuously taken without leaving an interval enough to compensate for new bubbles due to replacement of blood. Although the effect of the agent cannot be obtained, a technique for optimizing the imaging interval has not been conventionally known.

A signal intensity image of a signal component having the same frequency as the transmission frequency among the signal components of the ultrasonic echo (hereinafter, referred to as a signal intensity image).
A normal B-mode image) can express the structure of an organ well, and a signal intensity image (hereinafter, a harmonic B-mode image) of a signal component having a frequency that is an integral multiple of 2 or more of the transmission frequency among the signal components of the ultrasonic echo is Since the blood distribution can be expressed well, it is preferable that the diagnosis can be made while viewing both images simultaneously. However, imaging of the normal B-mode image and imaging of the harmonic B-mode image are different from each other, so that simultaneous imaging of both is not possible. For this reason, the conventional ultrasonic diagnostic apparatus has a problem that diagnosis cannot be performed while viewing both images at the same time.

Accordingly, a first object of the present invention is to provide an ultrasonic diagnostic apparatus capable of optimizing a transmission frequency so as to most closely match a contrast agent.

It is a second object of the present invention to provide an ultrasonic diagnostic apparatus capable of optimizing an imaging interval so as to leave an interval sufficient to sufficiently compensate for bubbles as a contrast agent.

It is a third object of the present invention to provide an ultrasonic diagnostic apparatus capable of performing a diagnosis while viewing a normal B-mode image and a harmonic B-mode image substantially simultaneously.

[0009]

According to a first aspect of the present invention, there is provided a transmission frequency changing means for changing a transmission frequency of an ultrasonic beam, and receiving an ultrasonic echo and receiving an ultrasonic echo at an integral multiple of 2 or more of the transmission frequency. A harmonic component acquisition unit for acquiring a frequency component (hereinafter, referred to as a harmonic component);
1) Integral value calculating means for calculating an integral value of the harmonic component of the whole or a part of a sound ray segment or n frames, and transmission corresponding to a maximum integral value by comparing the integral values corresponding to different transmission frequencies. An ultrasonic diagnostic apparatus comprising: an optimum transmission frequency determining unit that determines a frequency as an optimum transmission frequency. In the ultrasonic diagnostic apparatus according to the first aspect, the transmission frequency of the ultrasonic beam is changed in several steps, and the integrated value of the harmonic component at each transmission frequency is compared. Since the signal strength increases as the contrast agent and the transmission frequency match, the integral value also increases.
Therefore, the transmission frequency having the maximum integrated value is determined to be the transmission frequency most suitable for the contrast agent, and the transmission frequency can be optimized.

According to a second aspect of the present invention, in the ultrasonic diagnostic apparatus having the above configuration, the optimum transmission frequency and the type of the contrast agent used when the optimum transmission frequency was obtained are registered in association with each other. When the type of the contrast medium is designated and the optimal transmission frequency corresponding to the type is registered, the optimal transmission frequency reading means for reading out the optimal transmission frequency is provided. An ultrasonic diagnostic apparatus is provided. In the ultrasonic diagnostic apparatus according to the second aspect, the type of the contrast agent and the optimum transmission frequency are registered in association with each other, and when the type of the contrast agent is designated, the optimum transmission frequency is read out. Frequency can be optimized.

[0011] In a third aspect, the present invention provides a first signal intensity i _k of the ultrasonic echoes from the measurement point within the object by ultrasonic beams to destroy the bubbles existing as a contrast agent into the object ^- Signal strength measuring means for measuring the second signal strength i _k ⁺ after the time T _k , and setting the comparison coefficient w to 0 <w <1
Where, _ik ⁺ ≧ w · _ik ⁻ is determined, and the measurement and the determination are performed by changing the time T _k by the signal strength measuring means and the determining means. _Iteratively , _{find the} shortest time T _kmin satisfying the above inequality,
Intermittent scan interval setting means for setting a time _{equal to} or _longer than the shortest time T _kmin as an intermittent scan interval, and continuous imaging means for continuously capturing an ultrasonic image of the subject at the intermittent scan interval using the ultrasonic beam. An ultrasonic diagnostic apparatus characterized by comprising: In the above configuration, the comparison coefficient w is a value that can be determined empirically, and is, for example, 0.9. In the ultrasonic diagnostic apparatus according to the third aspect, the signal strength ik in a state in which bubbles exist ^- destroying bubbles by measuring. Next, after a lapse of the time T _k , the signal strength i _k ⁺ is measured again. If, if turnover blood is active, because rapidly bubbles by flow of containing bubbles blood is compensated, the signal strength in a relatively short time T _k i _k ⁺ signal intensity i _k ^- restored to. On the other hand, if the turnover of the blood is inactive, because the compensation of the bubbles is slow, relatively long time not to apply T _k and signal strength i _k ⁺ is the signal intensity i _k ^- not recovered to. In other words, signal strength i _k ⁺ signal strength i _k ^- the shortest time T _kmin coming recovered to (w × 100)% is, Kawari put the organs of blood is shortened if active, put the organs of blood It becomes longer if the exchange is inactive. Therefore, if the shortest time T _kmin is measured and the image is intermittently taken at a time interval longer than that, the image can always be taken in a state where the contrast agent is present, and the image taking interval can be optimized.

In a fourth aspect, the present invention provides a normal B-mode processing means for generating a signal intensity image of a signal component having the same frequency as a transmission frequency among signal components of an ultrasonic echo, Of which, a signal component having a frequency that is an integer multiple of 2 or more of the transmission frequency (hereinafter referred to as a harmonic component)
A harmonic B-mode processing means for generating a signal strength image of the following, a harmonic B-mode interrupt switch operated by an operator to turn on / off, and when the harmonic B-mode interrupt switch is off, the normal B-mode processing means is operated and Manual switching control means for suspending the harmonic B mode processing means, suspending the normal B mode processing means when the harmonic B mode interrupt switch is on, and operating the harmonic B mode processing means. To provide an ultrasonic diagnostic apparatus. In the ultrasonic diagnostic apparatus according to the fourth aspect,
If the operator turns off the harmonic B mode interrupt switch, an image in the normal B mode can be obtained. If the operator turns on the harmonic B mode interrupt switch, an image in the harmonic B mode can be obtained. Diagnosis can be performed while viewing the B-mode image substantially simultaneously.

According to a fifth aspect, the present invention provides a normal B-mode processing means for generating a signal intensity image of a signal component having the same frequency as the transmission frequency among signal components of an ultrasonic echo, Of which, a signal component having a frequency that is an integer multiple of 2 or more of the transmission frequency (hereinafter referred to as a harmonic component)
And a harmonic B mode processing means for generating a signal intensity image of the normal B mode for a first predetermined time and stopping the harmonic B mode processing means for a first predetermined time and a second predetermined time for the normal B mode processing. An ultrasonic diagnostic apparatus characterized by comprising automatic switching control means for repeating the operation of stopping the means and operating the harmonic B mode processing means. In the ultrasonic diagnostic apparatus according to the fifth aspect, the normal B-mode image and the harmonic B-mode image are alternately obtained at predetermined time intervals, so that the normal B-mode image and the harmonic B-mode image are alternately obtained. Can be diagnosed while looking at substantially simultaneously.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail with reference to the embodiments of the invention shown in the drawings. Note that the present invention is not limited by this.

FIG. 1 is a configuration diagram of an ultrasonic diagnostic apparatus according to one embodiment of the present invention. This ultrasonic diagnostic apparatus 100
Is an ultrasonic probe 1 that transmits an ultrasonic pulse and receives an ultrasonic echo, a transmission / reception control unit 2 that electronically scans a scanning plane to obtain a sound ray signal, and a signal component of the ultrasonic echo. Normal B-mode processing for generating image data of a signal intensity image of a signal component having the same frequency as the transmission frequency, and image data of a signal intensity image of a signal component having a frequency twice as high as the transmission frequency among the signal components of the ultrasonic echo. Harmonic B-mode processing to generate, CF (Color Flow) to generate image data based on the phase of the Doppler component of the ultrasonic echo
A signal processing unit 3 for performing mode processing, PD (Power Doppler) mode processing for generating image data based on the power of the Doppler component of the ultrasonic echo, a DSC 4 for generating a display image from the image data, and the display image , A control unit 6 for controlling the overall operation, and an input device 7 for inputting an instruction by an operator. The input device 7 includes a B-mode type selection switch 7a and an intermittent scan interval selection switch 7b.
And a foot switch 7c. It should be noted that a push button may be provided on the ultrasonic probe 1 instead of the foot switch 7c.

The operator executes the "normal" B-mode processing, the "harmonic" B-mode processing, and the normal B-mode processing when the operator does not press the foot switch 7c by using the B-mode type selection switch 7a. When the foot switch 7c is pressed, "manual mixing" B mode processing for executing harmonic B mode processing and "automatic mixing" B for automatically switching and executing normal B mode processing and harmonic B mode processing at predetermined time intervals. Mode processing can be alternatively selected.

Further, the operator can specify the number of seconds of the imaging interval in the harmonic B mode processing by using the intermittent scan interval selection switch 7b. If "Auto" is set, the intermittent scan interval is automatically optimized.

FIG. 2 is a flowchart showing the B-mode processing executed by the ultrasonic diagnostic apparatus 100. In addition,
It is assumed that a bubble as a contrast agent has been injected into the subject before the harmonic B mode processing is executed. In step D1, if "normal" is selected by the B-mode type selection switch 7a, the process proceeds to step D2, and if "normal" is not selected, the process proceeds to step D3. In step D2, normal B mode processing is executed,
A signal intensity image of a signal component having the same frequency as the transmission frequency among the signal components of the ultrasonic echo is captured and displayed. Then, when an interrupt occurs due to the change of the B mode type selection switch 7a, the process returns to the step D1.

In step D3, a transmission frequency automatic setting process is executed to optimize the transmission frequency in the harmonic B mode process. This transmission frequency automatic setting process will be described later with reference to FIG. In step D4, a transmission sound pressure automatic setting process is executed to optimize the transmission sound pressure in the harmonic B mode process. This transmission sound pressure automatic setting process will be described later with reference to FIG. Step D5
Then, if "auto" is not selected by the intermittent scan interval selection switch 7b, the process proceeds to step D6, and if "auto" is selected, the process proceeds to step D7. In step D6, the intermittent scan interval selection switch 7b
Set the number of seconds selected in to the intermittent scan interval.
Then, the process proceeds to step D8. In step D7, an intermittent scan interval automatic setting process is executed to optimize the imaging interval in the harmonic B mode process. This intermittent scan interval automatic setting process will be described later with reference to FIG.

In step D8, if "harmonic" is selected by the B-mode type selection switch 7a, the process proceeds to step D9, and if "harmonic" is not selected, the process proceeds to step D10. In step D9,
A harmonic B mode process is executed to capture and display a signal intensity image of a signal component having a frequency twice as high as the transmission frequency among the signal components of the ultrasonic echo. Then, when an interrupt occurs due to the change of the B mode type selection switch 7a, the process returns to the step D1. The transmission frequency and the transmission sound pressure in the harmonic B mode processing are
The transmission frequency and the transmission sound pressure determined in steps D3 and D4 are generally different from the transmission frequency and the transmission sound pressure in the normal B-mode processing.

In step D10, if "manual mixing" is selected by the B mode type selection switch 7a, the process proceeds to step D11, and if "manual mixing" is not selected, the process proceeds to step D12. In step D11, a manual mixing B mode process is executed. That is, when the operator does not press the foot switch 7c, the normal B mode process is executed, and when the operator presses the foot switch 7c, the harmonic B mode process is executed. This manual mixing B mode processing will be described later with reference to FIG. And
When an interrupt occurs due to the change of the B-mode type selection switch 7a, the process returns to the step D1.
In step D12, an automatic mixing B mode process is executed. That is, the normal B mode processing and the harmonic B mode processing are automatically switched and executed at predetermined time intervals.
This automatic mixing B mode processing will be described later with reference to FIG. Then, when an interrupt occurs due to the change of the B mode type selection switch 7a, the process returns to the step D1.

FIG. 3 is a flowchart showing the transmission frequency automatic setting process. In step F1, it is searched whether the optimum transmission frequency corresponding to the contrast agent to be used is registered. If it is registered, the process proceeds to step F2, and if not, the process proceeds to step F3. In step F2, the optimum transmission frequency corresponding to the contrast agent to be used is read out and set as the transmission frequency. Then, the process ends.

In step F3, the fundamental frequency (nominal resonance frequency) of the ultrasonic probe 1 in use is selected. In step F4, each transmission frequency (for example, from (fundamental frequency −3 · Δf) to (fundamental frequency + 3 · Δf) in increments of Δf)
1.5 MHz, 2 MHz,..., 3 MHz,..., 4.5 MHz).
A signal intensity image of a signal component having a double frequency is captured. Then, the pixel value is integrated for each signal intensity image. Here, the integral value of one frame is obtained, but the integral value of a part of one frame (for example, a region of interest specified by the operator) may be obtained, or several frames or each part of several frames may be obtained. May be calculated. Further, the integral value of the whole sound ray, a part of the sound ray, the whole sound ray, or each part of the sound ray may be obtained. In step F5, a transmission frequency at which the integrated value is maximized is obtained by using curve fitting or the like, and is set as the transmission frequency. Note that the relationship between the transmission frequency and the integrated value is the case where the maximum value is obtained at one point as shown in FIG. 4A, and the case where the maximum value is obtained at a plurality of points as shown in FIG. However, when there are maximum values at a plurality of points, the lowest transmission frequency among them is set as the optimum transmission frequency. In step F6, an inquiry is made to the operator as to whether or not to register. If registration is to be performed, the process proceeds to step F7, and if not to be registered, the process ends. In step F7, the transmission frequency is registered as the optimum transmission frequency in correspondence with the contrast agent.

FIG. 5 is a flowchart showing the transmission sound pressure automatic setting process. In step P1, it is searched whether or not the optimal transmission sound pressure corresponding to the contrast agent to be used is registered. If it is registered, the process proceeds to step P2, and if not, the process proceeds to step P3. In Step P2, the optimum transmission sound pressure corresponding to the contrast agent to be used is read out and set as the transmission sound pressure. Then, the process ends.

In step P3, the basic sound pressure of the ultrasonic probe 1 in use is selected. In step P4, each transmission sound pressure (for example, 0.4 Pa, 0.6 Pa,..., 1) in steps of ΔP from (basic sound pressure−3 · ΔP) to (basic sound pressure + 6 · ΔP).
, 2.2 Pa), and among the signal components of the ultrasonic echo, a signal intensity image of a signal component having a frequency twice as high as the transmission frequency is captured. Then, the pixel value is integrated for each signal intensity image. Here, the integral value of one entire frame is obtained, but the integral value of a part of one frame may be obtained, or the integral value of the whole several frames or each part of several frames may be obtained. Further, the integral value of the whole sound ray, a part of the sound ray, the whole sound ray, or each part of the sound ray may be obtained. In step P5, the transmission sound pressure at which the integrated value becomes the maximum is determined, and is set as the transmission sound pressure. Note that the relationship between the transmission sound pressure and the integrated value is the case where there is a maximum value at one point as shown in FIG. 6A, and the case where there is a maximum value at a plurality of points as shown in FIG. 6B. However, when there are maximum values at a plurality of points, the lowest transmission sound pressure among them is set as the optimum transmission sound pressure. In Step P6, the operator is inquired of whether or not to register. If the registration is to be performed, the process proceeds to Step P7, and if not to be registered, the process is terminated. In Step P7, the transmission sound pressure is registered as the optimum transmission sound pressure in association with the contrast agent.

FIG. 7 is a flowchart showing the intermittent scan interval automatic setting process. In step S1, a normal B-mode image is captured, and the operator sets a region of interest on the normal B-mode image. In step S2, the Tk table is read. This Tk table is a table that defines time T _k for k = 0, 1, 2,. The time T ₀ is a time during which the perfusion is sufficiently performed when the organ is normal. Also,
As k increases, time T _k increases. For example, T ₀ = 10 seconds, T ₁ = 0.5 seconds, T ₂ = 1 second, T ₃
= 2 seconds, T ₄ = 4 seconds,... Step S
At 3, the value of the sequence counter k is initialized to "1".

[0027] In step S4, after waiting for the elapse of the time T _0, the process proceeds to step S5. This is because the blood is sufficiently replaced, and the organs are sufficiently filled with air bubbles as a contrast medium. In step S5, transmits an ultrasonic beam to obtain a signal intensity of 2 times the frequency of the component of the transmission frequency of the signal component of the ultrasonic echo, the k pre-signal intensity i _k it ^- to. In step S6, the time T _k
, And then proceeds to step S7. In step S7, an ultrasonic beam is transmitted to obtain a signal intensity of a component having a frequency twice as high as the transmission frequency among the signal components of the ultrasonic echo, and this is set as a k-th signal intensity _ik ⁺ . In step S8, when a comparison coefficient ^{_{w = 0.9, i k + ≧}} w · i k - and it is judged whether or not the composed, to satisfy the inequality proceeds to step S9, satisfies the inequality step S1
Go to 0. In step S9, the value of k is increased by "1", and the process returns to step S5. In step S10, the time T _k and intermittent scanning interval. Then, the process ends. Note that a time _obtained by adding a margin time (for example, 1 second) to the time Tk may be set as the intermittent scan interval.

The [0028] above, as shown in FIG. 8, the first front signal intensity i ₁ ^- or the second image i ₁ ⁺ and after while being measured sequentially, intermittent scan interval is determined. This intermittent scan interval is a time period in which the signal intensity in the region of interest satisfies the above inequality and is _{equal to} or _longer than the shortest time T _kmin , and is a time period in which the region of interest is sufficiently supplemented with the contrast agent.

FIG. 9 is a flowchart showing the manual mixing B mode processing. The normal B mode and harmonic B mode images are displayed side by side on the screen. In step M1, a normal B-mode process is executed to capture and display a signal strength image of a signal component having the same frequency as the transmission frequency among the signal components of the ultrasonic echo. In step M2, if there is a termination instruction, the process is terminated, and if there is no termination instruction, the process proceeds to step M3. In step M3, if the foot switch 7c is not pressed, the process proceeds to step M4,
If so, the process proceeds to step M5. In step M4, if the harmonic B mode image is displayed, it is frozen, and if it is not displayed, nothing is performed, and
The process returns to step M1. In step M5, the normal B-mode image is frozen. In step M6, a harmonic B mode process is executed to capture and display a signal intensity image of a signal component having a frequency twice as high as the transmission frequency among the signal components of the ultrasonic echo. Then, the process returns to the step M3.

FIG. 10 is a flowchart showing the automatic mixing B mode processing. The normal B mode and harmonic B mode images are displayed side by side on the screen. In step A1, a normal B-mode process is executed to capture and display a signal strength image of a signal component having the same frequency as the transmission frequency among the signal components of the ultrasonic echo. In step A2,
If there is a termination instruction, the process is terminated. If there is no termination instruction, the process proceeds to step A3. In step A3, the normal B
If the time Tb has not elapsed since the start of the mode processing, the process proceeds to step A4, and if it has elapsed, the process proceeds to step A5. In step A4, if the harmonic B-mode image is displayed, it is frozen. If not, the process returns to step A1 without performing any operation. In step A5, the normal B-mode image is frozen. In step A6, a harmonic B mode process is executed to capture and display a signal intensity image of a signal component having a frequency twice as high as the transmission frequency among the signal components of the ultrasonic echo. Step A
In step 7, if the time Th has not elapsed since the start of the harmonic B mode processing, the process returns to step A6, and if it has elapsed, the process proceeds to step A4.

If the time Tb is set to the intermittent scan interval and the time Tb is set to one frame imaging time, the harmonic B mode image is updated at each intermittent scan interval as shown in FIG. , While normal B
The mode image will be updated.

According to the ultrasonic diagnostic apparatus 100 described above, the following effects can be obtained. (1) The transmission frequency and the transmission sound pressure can be optimized so as to best match the contrast agent. (2) The imaging interval can be optimized so as to leave an interval sufficient to sufficiently compensate for bubbles as a contrast agent. (3) When the foot switch 7c is pressed at a desired time while viewing the normal B mode image, the harmonic B mode image can be viewed only while the foot switch 7c is being pressed. (4) The normal B-mode image and the harmonic B-mode image are automatically updated without any operation, so that diagnosis can be performed while viewing both in substantially real time.

[0033]

According to the ultrasonic diagnostic apparatus of the present invention, the following effects can be obtained. (1) The transmission frequency can be optimized so as to best match the contrast agent. (2) The imaging interval can be optimized so as to leave an interval sufficient to sufficiently compensate for bubbles as a contrast agent. (3) Diagnosis can be performed while viewing the normal B-mode image and the harmonic B-mode image substantially simultaneously.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an ultrasonic diagnostic apparatus according to one embodiment of the present invention.

FIG. 2 is a flowchart showing a B-mode process of the ultrasonic diagnostic apparatus of FIG. 1;

FIG. 3 is a flowchart showing a transmission frequency automatic setting process of the ultrasonic diagnostic apparatus of FIG. 1;

FIG. 4 is an exemplary diagram of a relationship between a transmission frequency and an integrated value.

FIG. 5 is a flowchart showing a transmission sound pressure automatic setting process of the ultrasonic diagnostic apparatus of FIG. 1;

FIG. 6 is an illustration of a relationship between a transmission sound pressure and an integral value.

FIG. 7 is a flowchart showing an intermittent scan interval automatic setting process of the ultrasonic diagnostic apparatus of FIG. 1;

FIG. 8 is a time chart showing an imaging sequence for determining an intermittent scan interval.

FIG. 9 is a flowchart showing manual mixing B-mode processing of the ultrasonic diagnostic apparatus of FIG. 1;

FIG. 10 is a flowchart showing an automatic mixing B-mode process of the ultrasonic diagnostic apparatus of FIG. 1;

FIG. 11 is a time chart showing an imaging sequence in the automatic mixing B mode processing of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ultrasonic probe 2 Transmission / reception control part 3 Signal processing part 6 Control part 7 Input device 7a B mode type selection switch 7b Intermittent scan interval selection switch 7c Foot switch

Claims (5)

[Claims] 1. A transmission frequency changing means for changing a transmission frequency of an ultrasonic beam, and a harmonic for receiving an ultrasonic echo and acquiring a component having a frequency of an integral multiple of 2 or more of the transmission frequency (hereinafter referred to as a harmonic component). A component acquisition unit, an integral value calculating unit that calculates an integral value of the harmonic component of the whole or a part of n (≧ 1) sound ray segments or n frames, and an integral value corresponding to a different transmission frequency. An ultrasonic diagnostic apparatus comprising: an optimal transmission frequency determining unit that determines a transmission frequency corresponding to a maximum integral value as an optimal transmission frequency. 2. The ultrasonic transmission apparatus according to claim 1, wherein said optimum transmission frequency is registered in correspondence with the type of a contrast agent used when said optimum transmission frequency was obtained. And an optimum transmission frequency reading means for reading out, when a type of the contrast agent is designated, an optimum transmission frequency corresponding to the type, if the type is registered, the ultrasonic diagnostic apparatus. Wherein the first signal intensity i _k of the ultrasonic echoes from the measurement point within the object by ultrasonic beams to destroy the bubbles existing as a contrast agent into the object ^- and subsequently measures the time T
a signal strength measuring means for measuring a second signal strength i _k ⁺ after _k, when the comparison coefficients w to _{0 <w <1, i k} + ≧ w · i
_k ^- become or judging means for judging whether, by repeating the above determination and the measurement while changing the time T _k by said determining means and said signal strength measuring means, the shortest time T _kmin satisfying the inequality And an intermittent scan interval setting means for setting a time interval _{equal to} or _longer than the shortest time T _kmin as an intermittent scan interval, and continuously taking an ultrasonic image of the subject at the intermittent scan interval using the ultrasonic beam. An ultrasonic diagnostic apparatus comprising: a continuous imaging unit. 4. A normal B-mode processing means for generating a signal intensity image of a signal component having the same frequency as a transmission frequency among signal components of an ultrasonic echo, and an integer of 2 or more of a transmission frequency among signal components of an ultrasonic echo. A harmonic B mode processing means for generating a signal intensity image of a signal component of a double frequency (hereinafter, referred to as a harmonic component), a harmonic B mode interrupt switch operated by an operator on / off, and the harmonic B mode interrupt switch turned off When the normal B mode processing means is activated, the harmonic B mode processing means is paused, and when the harmonic B mode interrupt switch is on, the normal B mode processing means is paused and the harmonic B mode processing means is stopped. Ultrasound diagnostics comprising manual switching control means for operating Cutting device. 5. A normal B-mode processing means for generating a signal intensity image of a signal component having the same frequency as a transmission frequency among signal components of an ultrasonic echo, and an integer of 2 or more of a transmission frequency among signal components of an ultrasonic echo. A harmonic B-mode processing unit for generating a signal intensity image of a signal component of a double frequency (hereinafter, referred to as a harmonic component), and the normal B-mode processing unit is operated and the harmonic B-mode processing unit is stopped for a first predetermined time. And an automatic switching control means for repeatedly stopping the normal B-mode processing means and activating the harmonic B-mode processing means for a second predetermined time.