JP2006192031A - Ultrasonic image diagnostic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultrasonic image diagnostic device capable of detecting signals from a weak blood flow in a continuous wave Doppler mode. <P>SOLUTION: In the ultrasonic diagnostic device 1 capable of an operation in the continuous wave Doppler mode, a switching part 13 for switching a plurality of ultrasonic vibration elements arranged in parallel to the electronic scanning direction of an ultrasonic probe 50 to the ultrasonic vibration elements Tx for transmission and the ultrasonic vibration elements Rx for reception and operating them is provided, and a control part 11 for controlling the switching part can change the number and/or position of the ultrasonic vibration elements to be allocated to the ultrasonic vibration elements for the transmission and the ultrasonic vibration elements for the reception. Thus, the saturation of a reception circuit by unrequired signals from parts other than the vicinity of a focus is reduced and a weaker blood flow is detected. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an ultrasound diagnostic imaging apparatus that scans a subject with ultrasound and obtains and displays a tomographic image and blood flow information based on an obtained echo signal.

  The ultrasonic diagnostic imaging apparatus transmits ultrasonic waves to a subject and receives reflected waves from an array vibration element including a plurality of ultrasonic vibration elements. In this array vibration element generally used, a plurality of ultrasonic vibration elements are arranged in a line, and transmission / reception control is electronically performed on each ultrasonic vibration element. Thereby, an ultrasonic beam is formed, and the ultrasonic beam is electronically scanned in the arrangement direction of the ultrasonic vibration elements.

  The ultrasonic diagnostic imaging apparatus includes a B mode for observing a tomographic image of a soft tissue of a living body, and a temporal structure of a heart, a blood vessel, or the like by arranging the one-line tissue images in parallel along the time axis. There are various operation modes such as an M mode for observing changes in detail and a Doppler mode for acquiring a blood flow spectrum and a spatial spread using the Doppler effect. The Doppler mode includes a continuous wave (CW) Doppler mode and a pulse (PW) Doppler mode. Of the Doppler modes, the continuous wave Doppler mode is useful for accurately detecting relatively fast blood flow velocity data, and the pulse Doppler mode forms a color flow image that displays a two-dimensional blood flow image in color. It is known to be useful for obtaining velocity data for

By the way, for example, in order to obtain a B-mode image or a pulsed Doppler mode blood flow image using an array vibration element in which 128 ultrasonic vibration elements are arranged, transmission and reception are performed by scanning a certain region with an ultrasonic beam. And tomographic images by processing the obtained echo signals alternately. At this time, almost all 128 ultrasonic transducer elements are driven alternately for transmission and reception. On the other hand, when an array vibration element in which the same 128 ultrasonic vibration elements are arrayed is used for the continuous wave Doppler mode, it is necessary to continuously transmit and receive ultrasonic waves. In other words, 64 ultrasonic vibration elements are used for transmission, and the other 64 ultrasonic vibration elements are used for reception (see, for example, Patent Document 1).
JP-A-8-52134

  By the way, when the array resonator element is fixed by being divided into two equal parts from the center to the left and right, there is a problem that the degree of freedom of ultrasonic beam formation in transmission and reception is small. On the other hand, clinically, there is a need to detect weaker blood flow in CW Doppler mode. However, since the CW Doppler mode does not have information regarding the distance, the reception ultrasonic vibration element captures all signals on the reception beam. In particular, the receiving circuit is saturated by receiving a strong unnecessary reflected signal (clutter) from a stationary body near the body surface of the subject, and thus there is a problem that a signal from a weak blood flow cannot be detected.

  The present invention has been made to solve such problems.

  In order to solve the above-described problem, the invention according to claim 1 is configured to operate in a continuous wave Doppler mode that receives a reflected wave based on an ultrasonic wave continuously transmitted to a subject and obtains blood flow information. In a possible ultrasonic diagnostic imaging apparatus, control is performed by switching an array vibration element in which a plurality of ultrasonic vibration elements are arranged in parallel in the electronic scanning direction to a transmission ultrasonic vibration element and a reception ultrasonic vibration element. The control means is capable of changing the number and / or position of the ultrasonic vibration elements assigned to the transmission ultrasonic vibration element and the reception ultrasonic vibration element.

  According to a second aspect of the present invention, in the ultrasonic diagnostic imaging apparatus according to the first aspect, the control means uses a central portion of the array vibration element as a transmission ultrasonic vibration element, and transmits the transmission ultrasonic wave. Both ends of the vibration element are assigned as receiving ultrasonic vibration elements.

  Further, the invention according to claim 3 is the ultrasonic diagnostic imaging apparatus according to claim 2, wherein the number of the reception ultrasonic vibration elements allocated to both ends of the transmission ultrasonic vibration element is the transmission frequency. More than the number of trusted ultrasonic vibration elements, respectively.

  According to a fourth aspect of the present invention, in the ultrasonic diagnostic imaging apparatus according to any one of the first to third aspects, the transmission ultrasonic vibration element and the reception ultrasonic vibration element include: Weighting is performed to reduce the sensitivity of the end portion of each central portion.

  As shown in the section of the means for solving the above problems, according to the invention of each claim described in the claims of the present invention, the following effects can be obtained.

  According to the first aspect of the present invention, the degree of freedom of beam formation in the continuous wave Doppler mode can be increased, and optimization can be performed according to the purpose.

  According to the second aspect of the present invention, saturation of the receiving circuit due to unnecessary strong signals other than blood flow such as clutter can be avoided, and blood flow detection sensitivity can be improved.

  According to the third aspect of the invention, compared to the second aspect of the invention, the reception beam at a shorter distance than the focal point can be weakened to avoid strong clutter from the vicinity of the body surface of the subject. It is possible to reduce the saturation of the receiving circuit due to unnecessary signals from other than the vicinity of the focal point, and to detect weaker blood flow.

  According to the fourth aspect of the present invention, side lobes can be lowered, saturation of the receiving circuit due to unnecessary received signals from other than the direction of the received beam can be avoided, and blood flow detection sensitivity can be further improved. .

  Hereinafter, an embodiment of an ultrasonic diagnostic imaging apparatus according to the present invention will be described in detail with reference to FIGS.

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

  As shown in FIG. 1, an ultrasonic diagnostic imaging apparatus 1 includes an ultrasonic diagnostic imaging apparatus main body 10 and a monitor 30 that is usually placed on the ultrasonic diagnostic imaging apparatus main body 10 and displays an ultrasonic image and the like. An operation unit 40 for a user to input necessary data and select various functions to the ultrasonic diagnostic imaging apparatus main body 10, and an ultrasonic wave is transmitted to the subject and a reflected wave is received. And an ultrasonic probe 50 composed of an array vibration element in which a plurality of ultrasonic vibration elements are arranged in parallel. The ultrasonic probe 50 is normally detachable from the ultrasonic diagnostic imaging apparatus main body 10. ing.

  The ultrasonic diagnostic imaging apparatus main body 10 includes a control unit 11, a transmission / reception unit 12, a switching unit 13, a signal processing unit 14, and a display processing unit 15. The control unit 11 is instructed from the operation unit 40 or programmed in advance. Each component device such as the transmission / reception unit 12, the switching unit 13, the signal processing unit 14, and the display processing unit 15 is organically controlled according to the procedure. For example, the operation of the transmission / reception unit 12 is controlled based on the basic clock from the control unit 11. The transmission / reception unit 12 includes a transmission circuit 16 and a reception circuit 17, and the signal processing unit 14 includes, for example, a Doppler signal processing circuit 18 and a B-mode signal processing circuit 19. Furthermore, the receiving circuit 17 includes a preamplifier 21, a quadrature detector 22, and a reference signal generator 23 as shown in FIG.

  The operation unit 40 is connected to the control unit 11 and includes a keyboard, a trackball, a switch, and the like so that the user can input necessary data and select various functions.

  The ultrasonic probe 50 is used while being in contact with a subject. For example, the ultrasonic probe 50 includes an array vibration element in which 128 ultrasonic vibration elements are arranged in a horizontal row, and is composed of an electronic linear scanning method or an electronic sector scanning method. The desired diagnostic region of the subject is scanned with an ultrasonic beam formed by a scanning method such as the above.

  The ultrasonic probe 50 is coupled to the ultrasonic diagnostic imaging apparatus main body 10 by a connector (not shown), and is electrically connected to the transmission / reception unit 12 via the switching unit 13. Under the control of the control unit 11, the switching unit 13 switches the connection relationship between each ultrasonic vibration element of the ultrasonic probe 50 and the transmission circuit 16 or the reception circuit 17 of the transmission / reception unit 12 according to the operation mode. The connection relationship is switched according to, for example, switching between the B mode and the CW Doppler mode. That is, when either the B mode or the CW Doppler mode is selected by the operation unit 40, switching of transmission / reception of the ultrasonic probe 50 by the switching unit 13 or each ultrasonic wave of the ultrasonic probe 50 is selected according to the selected mode. The switching of the connection relationship between the vibration element and the transmission circuit 16 and the reception circuit 17 is controlled.

  Next, a case where the ultrasonic diagnostic imaging apparatus 1 configured as described above is operated in the CW Doppler mode will be described.

  FIG. 3 shows a connection relationship between each ultrasonic transducer element of the ultrasonic probe 50 and the transmission circuit 16 and the reception circuit 17 in the case of the CW Doppler mode. The ultrasonic probe 50 is not specially designed for the present invention, and may be one normally used in a general ultrasonic diagnostic imaging apparatus.

  That is, when the ultrasonic diagnostic imaging apparatus 1 is operated in the CW Doppler mode, in the present invention, for example, the ultrasonic probe 50 composed of 128 ultrasonic vibration elements is apparently divided into three, and the ultrasonic probe in the central portion is divided. The ultrasonic vibration element group is a transmission vibration element Tx, and the ultrasonic vibration element groups on both sides thereof are reception vibration elements Rx1 and Rx2. Here, the number of ultrasonic vibration elements constituting the reception vibration elements Rx1 and Rx2 is the same (Rx1 = Rx2), and the number of ultrasonic vibration elements constituting the reception vibration elements Rx1 and Rx2 is the transmission vibration element. The number is larger than the number of ultrasonic vibration elements constituting Tx (Tx <Rx1 = Rx2).

  The transmission vibration element Tx is switched by the switching unit 13 such that the transmission vibration element Tx is connected to the transmission circuit 16 and the reception vibration elements Rx1 and Rx2 are connected to the reception circuit 17. The switching unit 13 that performs this switching is omitted in FIG. 3 in order to avoid the complexity of the figure. There may be several dummy vibrating elements that are not used for transmission or reception at the boundary between the transmitting vibrating element Tx and the receiving vibrating elements Rx1 and Rx2 on both sides thereof.

  When the user inputs an instruction to operate the ultrasonic diagnostic imaging apparatus 1 in the CW Doppler mode from the operation unit 40, the control unit 11 receives the instruction and sets each component device in the CW Doppler mode. Set as follows. That is, the transmission circuit 16 has a predetermined delay for each ultrasonic vibration element constituting the transmission vibration element Tx with respect to the transmission vibration element Tx assigned for transmission by the switching unit 13 under the control of the control unit 11. The applied transmission signal is supplied, and the ultrasonic beam converged toward the subject is transmitted from the transmitting vibration element Tx. At the same time, the reflected wave by the transmitted ultrasonic beam is received by the ultrasonic vibration elements constituting the reception vibration elements Rx1 and Rx2 that are also assigned for reception by the switching unit 13, and is received as a reception echo signal. 17 is supplied.

  The reception circuit 17 is configured as shown in FIG. 2, so that the received echo signal is amplified by the preamplifier 21, and the quadrature detector 22 uses the reference signal from the reference signal generator 23 for reception. After performing the process of adjusting the phase difference of the signals between the ultrasonic vibration elements constituting the vibration elements Rx1 and Rx2, the signal is output to the Doppler signal processing circuit 18 of the signal processing unit 14 as a reception signal.

  The Doppler signal processing circuit 18 is composed of an A / D converter, a fast Fourier transformer, and the like, and analyzes the frequency spectrum of Doppler information included in the received signal of the ultrasonic beam for Doppler measurement. Is output to the display processing unit 15. Further, the display processing unit 15 performs necessary processing on the signal supplied from the Doppler signal processing circuit 18 to generate a Doppler waveform image and signal sound, and supplies the Doppler waveform image to the monitor 30 for display. The signal sound is supplied to an audio speaker (not shown).

  The effect of the present invention will now be described with reference to FIG. FIG. 4 schematically shows the pattern of transmission and reception of an ultrasonic beam to the subject by the ultrasonic probe 50.

  As shown in FIG. 4, the ultrasonic probe 50 is brought into contact with the body surface of the subject P for diagnosis. From the transmitting vibration element Tx of the ultrasonic probe 50, an ultrasonic beam converged so as to be focused on the region of interest ROI of the subject P by transmission delay control is transmitted. Then, the echo signal is received by the receiving vibration elements Rx1 and Rx2 whose reception delay is controlled so as to mainly receive the reflected wave from the region of interest ROI.

  By the way, the echo signal is not generated only from the region of interest ROI but generated from all paths of the ultrasonic beam transmitted from the transmitting vibration element Tx. In particular, strong clutter occurs near the body surface of the subject P in contact with the transmitting vibration element Tx. In the conventional technique, when this strong clutter is received by the receiving vibration element Rx and supplied to the receiving circuit, the preamplifier is saturated because the signal level is large, and a weak signal is extracted. It becomes impossible.

  However, as in the present invention, the transmitting vibration element Tx is provided at the center of the ultrasonic probe 50, and the receiving vibration elements Rx1 and Rx2 are provided on both sides thereof. An ultrasonic beam converged on the region ROI is transmitted, and echo signals are received with directivity in the region of interest ROI by the receiving vibrating elements Rx1 and Rx2 arranged on both sides of the transmitting vibrating element Tx. Can be. Therefore, it is possible to weaken the reception intensity at the receiving vibration elements Rx1 and Rx2 of the echo signal from the region of interest ROI, that is, the distance closer to the focal point, in other words, near the body surface of the subject. Therefore, since saturation of the preamplifier 21 due to reception of unnecessary signals from the region of interest ROI, that is, other than the vicinity of the focus, can be reduced, weaker blood flow can be detected.

  In FIG. 4, reference numeral 51 indicates the transmission direction of the ultrasonic beam, and reference numeral 52 indicates a particularly cluttered region. In the present invention, reception of clutter from this region 52 can be reduced. .

  Next, the case where the ultrasonic diagnostic imaging apparatus 1 is operated in the B mode will be described. The operation in the B mode is the same as that of a general ultrasonic diagnostic imaging apparatus, and will be described briefly.

  When the user performs an operation of switching to the operation in the B mode by the operation unit 40, all the ultrasonic vibration elements (for example, 128) of the ultrasonic probe 50 are operated by the operation of the switching unit 13 under the control of the control unit 11. It is connected to the transmission circuit 16 at the time of transmission and to the reception circuit 17 at the time of reception. That is, as the ultrasonic vibration element of the ultrasonic probe 50, the transmission vibration element Tx and the reception vibration elements Rx1 and Rx2 are not classified.

  The transmission / reception unit 12 performs transmission delay control and reception delay control to form an ultrasonic beam for tomographic images, and the reception signal is output to the B-mode signal processing circuit 19 of the signal processing unit 14. The B-mode signal processing circuit 19 performs processing such as envelope detection and logarithmic compression of the input received signal, and its output is subjected to processing such as coordinate conversion and data interpolation in the display processing unit 15 to thereby generate a B-mode tomogram. The tomographic image is formed on the monitor 30 and displayed on the monitor 30.

  The present invention is not limited to the above-described embodiments, and can be implemented in various modes without departing from the scope of the invention. For example, in the CW Doppler mode, with respect to the number of ultrasonic vibration elements constituting the transmission vibration element Tx and the number of ultrasonic vibration elements constituting the reception vibration elements Rx1 and Rx2, the superstructures constituting the reception vibration elements Rx1 and Rx2 It has been described that the number of the ultrasonic vibration elements is larger than the number of ultrasonic vibration elements constituting the transmission vibration element Tx (Tx <Rx1 = Rx2). However, this is an advantageous condition in practice that the reception of clutter from other than the vicinity of the focal point can be further reduced. However, this is not necessarily the case, and the transmission vibration element Tx and the reception vibration elements Rx1 and Rx2 are configured. The number of ultrasonic vibration elements to be performed may be substantially the same.

  Furthermore, according to the direction of the ultrasonic beam and the position of the focal point, the ratio of the number of ultrasonic vibration elements constituting the transmission vibration element and the reception vibration element and the position of the ultrasonic vibration element assigned to transmission / reception can be changed as appropriate. You may do it.

  Further, at the time of operation in the CW Doppler mode, both ends of the ultrasonic vibration elements that constitute the transmission vibration element Tx and the reception vibration elements Rx1 and Rx2 are assigned to the ultrasonic vibration elements that form the ultrasonic probe 50. You may make it weight so that the sensitivity of the both ends of the ultrasonic vibration element to comprise may be made lower than the sensitivity of each center part. In this way, the side lobes can be reduced, avoiding saturation of the receiving circuit due to reception of unnecessary signals from other than the transmission / reception direction, and weak doppler signals from the region of interest better. Blood flow detection sensitivity for collecting can be improved.

  As described above in detail, according to the present invention, saturation of the receiving circuit due to unnecessary strong signals other than blood flow such as clutter can be avoided, and blood flow detection sensitivity in the CW Doppler mode can be improved.

1 is a system diagram showing an embodiment of an ultrasonic diagnostic imaging apparatus according to the present invention. FIG. 2 is a system diagram illustrating a configuration of a receiving circuit illustrated in FIG. 1. It is explanatory drawing which showed the connection relationship between each ultrasonic transducer | vibrator of an ultrasonic probe in the case of CW Doppler mode, a transmission circuit, and a receiving circuit. It is explanatory drawing which showed typically the pattern of the transmission and reception of an ultrasonic beam in the case of CW Doppler mode.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ultrasonic diagnostic imaging apparatus 10 Ultrasonic diagnostic imaging apparatus main body 11 Control part 12 Transmission / reception part 13 Switching part 14 Signal processing part 15 Display processing part 16 Transmission circuit 17 Reception circuit 18 Doppler signal processing circuit 19 B mode signal processing circuit 30 Monitor 40 Operation unit 50 Ultrasonic probe P Subject Rx1, Rx2 Receiving vibration element ROI Region of interest (focus)
Tx transmission vibration element

Claims (4)

In an ultrasonic diagnostic imaging apparatus capable of operating in continuous wave Doppler mode to receive blood flow information by receiving a reflected wave based on an ultrasonic wave continuously transmitted to a subject,
The control means comprises a control means for switching and operating an array vibration element in which a plurality of ultrasonic vibration elements are arranged in parallel in the electronic scanning direction between a transmission ultrasonic vibration element and a reception ultrasonic vibration element. An ultrasonic diagnostic imaging apparatus characterized in that the number and / or position of the ultrasonic vibration elements assigned to the transmission ultrasonic vibration element and the reception ultrasonic vibration element can be changed. 2. The control unit according to claim 1, wherein a central portion of the array vibration element is assigned as a transmission ultrasonic vibration element, and both end portions of the transmission ultrasonic vibration element are assigned as reception ultrasonic vibration elements. Ultrasonic diagnostic imaging equipment. 3. The ultrasonic wave according to claim 2, wherein the number of the reception ultrasonic vibration elements allocated to both ends of the transmission ultrasonic vibration element is greater than the number of the transmission ultrasonic vibration elements. Diagnostic imaging device. 4. The transmission ultrasonic vibration element and the reception ultrasonic vibration element are each weighted so as to reduce the sensitivity of the end portion with respect to the central portion thereof. The ultrasonic diagnostic imaging apparatus according to any one of the above.

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