JPH08107897A - Ultrasonic wave imaging device operation method and ultrasonic wave imaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify the use of continuous wave(CW) Doppler operating mode by operating a multiple element transducer array and its associated delay and signal processing unit based upon the position of a user selected area of sensitivity. SOLUTION: A user of the apparatus can select the CW Doppler sensitive area of the displayed image by operating a controllable interface 21. A system controller 20 conveys a moderate delay to transmitting and receiving beam formers 7, 12, controls the steering and focusing of the transmitting and receiving beams which overlap in the selected area, and obtains the Doppler data indicating the movement in the volume of a body. The obtaining of the CW Doppler data is preferably carried out by a B mode and/or color float image in time division complex. Thus it is possible to simplify the use of the CW Doppler operating mode.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method of operating an ultrasound imaging device to acquire continuous wave (CW) Doppler data from a region selected by a user and to the ultrasound imaging device. More particularly, the present invention is an ultrasonic Doppler diagnostic device having a continuous wave (CW) Doppler mode, and in particular, the Doppler sensitivity of the imaged region to obtain Doppler information from the region selected by the user in question. A method and apparatus for user selection of parts and subsequent control of CW Doppler mode.

[0002]

BACKGROUND OF THE INVENTION Ultrasonic Doppler methods are commonly used to non-invasively detect and measure movement in the body, for non-invasive diagnostic analysis of blood flow in a patient, such as the patient's heart, Widely used in medical ultrasound scanners for detecting and measuring blood vessels and the like.

There are basically two modes of operation of ultrasonic Doppler, continuous wave (CW) and pulsed (PW) modes. PW mode is especially a two-dimensional blood flow image (image)
Useful to obtain velocity data used to generate (color flow image). However, since the pulse repetition rate (PRF) of the PW software system limits the maximum flow velocity (which can be determined without aliasing), the CW mode obtains velocity data for accurate determination of relatively high flow velocity. Especially useful for.

Additionally, ultrasonic diagnostic equipment conventionally produces so-called B-mode images, which are basically two-dimensional tomographic images known to those skilled in the art. B-mode images are generated using a transducer that can scan one area,
One of several types of multi-element transducer arrays, as known to those skilled in the art, eg 64
Or use a linear array of 128 transducer elements. CW Doppler operation, on the other hand, generally comprises a special transducer probe (which has two transducers, one for transmitting and one for receiving (also known to those skilled in the art, commonly referred to as pencil probe)). Need. For clarity, it is desirable that a single probe use its receive signal processing circuitry to obtain useful data not only in Doppler mode but also in B mode. One technique for accomplishing this is US Pat. No. 4,915,115, entitled "U1trasoni."
cImaging Apparatus for Di
spraying B-Mode and Doppl
er-Mode Images "Publications April
10, 1990 Sasaki et al. Is shown in. As described therein, the data is obtained by first actuating the transducer array via conventional transmit / receive control circuitry to cause steering and focusing of the transmitted ultrasonic pulses, with appropriate individual delays. The received signal can be fed to a conventional beamformer and image processor to produce a B-mode image. The user may then observe the B-mode image and use the cursor to mark the image along the beam direction, from which it is desired to obtain PW Doppler data, with an indication of the beam direction and depth. The transducer is then operated in PW Doppler mode and is adapted to receive Doppler signals therefrom using range gating techniques and to sequentially generate Doppler data.
It should be noted that the CW Doppler mode is Sasaki e
Not described by t al. Instead Sa
Saki et al discusses the receiving efficiency of a transducer when it is desirable to be able to operate in both Doppler and B modes, and in order to solve this problem, an ultrasonic transducer having two peaks in its receiving efficiency characteristic curve. , Where one is centered at the frequency used for B-mode imaging and the other at the number of frequencies used for PW Doppler data acquisition.

It is desirable to use a multiple element transducer array for CW Doppler mode,
This is due to the ability to control transmit and receive beam steering and focusing as well as improved S / N ratio performance, as well as better choice of Doppler sample volume (overlap region between CW transmit and receive beams). . U.S. Pat. No. 4,598,58
No. 9 Specification "Method of CW Dopple
r Imaging Using Variably
Focused Ultrasonic Transd
ucer Array "publication Jul 8, 198
6 Rilsy et al. Then improved S / NC
Although a circuit for operating such multiple elements to obtain a W Doppler image is shown, it will be described how the user of the equipment selects or controls steering and / or focusing of the CW Doppler beam. Has not been suggested. US Patent Specification No. 4,91
5,115 or US Pat. No. 4,416,286.
Issue name "U1trasound Blood Flow
"Measuring Apparatus" publication
November 22, 1983 Iinuma et
al. The prior art used for PW Doppler, as also shown in Figure 1, is not available because CW Doppler does not use range gates and therefore "" along a given receive beamline. This is because the selection of "depth" is inappropriate.

[0006]

An object of the present invention is to facilitate use of a CW Doppler operation mode of an ultrasonic imaging device using multiple elements.

A further object of the present invention is to enable a user control (method) for selecting the CW Doppler sensitivity (sensitivity) region in the two-dimensional ultrasonic image to be displayed.

Still another object of the present invention is to realize such a user control (method) not only with a simple and low-cost device cost but also with a method that can be easily controlled by the user. .

[0009]

SUMMARY OF THE INVENTION The present invention is directed to a method and apparatus for operating an ultrasound imaging device to acquire continuous wave (CW) Doppler data from a user selected region. Activating a multi-element transducer array and associated controllable delay and signal processing circuits to generate and display a two-dimensional ultrasound image in substantially real time, activating a controllable device by a user, said display Ultrasonic wave, wherein it is desired to cause the display of at least one controllable position marker in substantially real time in the two-dimensional ultrasound image to be obtained, for which the CW Doppler data is obtained. One area of sensitivity in the image should be selected so that the multiple element The actuation of the transducer array and the controllable delay and signal processing circuit is performed based on the position of the area of the sensitivity selected by the user, whereby 1) CW is performed using a predetermined number of multiple elements. Transmitting a steered beam of ultrasonic waves through the selected region of sensitivity, 2) passing through the selected region of sensitivity using a predetermined number of multiple elements; Steering receive beam passing through and processing the receive beam to produce a Doppler image display, which display is within the region of sensitivity selected by the user. It represents movement.

According to a further aspect of the present invention, a predetermined number of multiple elements are also provided for transmitting and receiving a steered beam of CW ultrasonic waves through a selected region of said sensitivity. Yes, the multiple elements are also used to focus the steered transmit and receive beams arriving through the selected region of sensitivity.

The above and other objects of the invention will be apparent from the following detailed description of advantageous embodiments of the invention.

[0012]

The present invention will be described below with reference to the illustrated embodiments.

FIG. 1 shows an ultrasonic medical imaging system to which the present invention may be applied. The system includes an ultrasonic probe 6 having multiple piezoelectric transducer elements (the elements being arranged, for example, in a linear array).
The transmission beam former 7, the analog preamplifier section 8, and the A / D converter 10 are included. Additionally, the system includes a digital receive beamformer 12, a demodulator 14, a scan converter 16, a Doppler processor 18, and a system controller 20. As is known, the transmit beamformer 7 has a controllable delay means for providing controllable focusing and steering of the ultrasound beam transmitted into the patient via the probe 6, and the receive beamformer. The shaper 12 has controllable delay means for generating a receive beam from the received echo via controllable focusing and steering,
The echo is caused by the reflection of the ultrasonic beam transmitted in the patient and is under the control of all system controllers 20.

The system controller 20 has a user interface means having a device device such as a keyboard, a trackball or the like (not specifically shown), and depending on the device device, the operator of the system may use the system B It can be in imaging (so-called luminance) mode PW Doppler mode, simultaneous B-imaging / PW mode or CW Doppler mode. In the B-imaging mode, the beamformer 12 produces an RF signal at its output, which RF signal is of the ultrasonic echoes received along a series of scanning lines extending across the patient's cross-section. Represents strength. The RF signals are demodulated by demodulator 14, which substantially performs the detection function on the RF signals produced during the B imaging mode. The generated detection image signal generated on the output side of the demodulator 14 is transferred to the scan converter 16. As is known, the scan converter accumulates echo data for scan lines that form a single frame of image 16. For the sector scan format, the scan converter also converts such data into a rectangular raster scan format, which is suitable for display on a video monitor. Then sequential sequential image frames are displayed in real time on the video image display 22.
Displayed above.

When the system is set to PW Doppler mode by the user, the operator marks the position of the sample volume (from which PW Doppler data should be collected) (checks and marks B-mode image). By that). The marked volume is correlated with the sample cell at the selected range along the selected scan converter, while for CW Doppler the sensitized volume is traditionally cylindrical and has a length to the scanline. Extend along. However, in the disclosed preferred embodiment using a multi-element transducer array, a focused and steered CW Doppler beam is possible, and therefore a focused and steered CW transmission with proper control of transmit and receive delays. And CW receive beams can be overlapped. The receive beamformer 12 is a continuous RF beamline, which represents the echo signal received from the beam direction containing the selected Doppler sensitive volume. The demodulator 14 converts the RF beamline signal generated during Doppler mode to baseband or intermediate frequency and produces demodulated in-phase (I) and quadrature (Q) signals at its output. The signal is provided to the Doppler processor 18. The signals I and Q are collectively referred to as "Doppler signals". Doppler processor 18 processes the Doppler signal and provides the signal to Doppler display 24. The display not only displays the video output of the spatial characteristics of the Doppler signal (ie the Doppler image) on the video display, but also the audio output (this is the sound audible by the Doppler audio display, the sound like a speaker (especially shown). The construction and operation of a substantial portion of each of the individual components described above are known to the patient and are further than those constructions and operations not necessary for an understanding of the invention. The description of US Pat. No. 59 is hereby incorporated by reference.
No. 8,589 discloses a control technique for CW Doppler image generation (but using analog signal processing techniques).

FIG. 2 is a block diagram of FIG. 1 using a digital beam generator.
Details of the configuration for each part of the ultrasonic device in FIG. Digital beam shapers are particularly advantageous because they allow relatively direct microprocessor control of beam focusing and steering. Where appropriate, the same reference numbers are used to indicate the same parts of the ultrasound system. For clarity,
Only the receiving part of the medical ultrasound device is shown, the transmitting part is omitted. Because they are traditional digital designs and behaviours. This is because the probe has a plurality of individual transducer elements 202 as shown in FIG. Each element 202 has a signal processing channel, which has an analog preamplifier 204 and an A / D converter 206.
The A / D converter supplies the digitized received ultrasonic echo signal to the digital beam former 12. As described in connection with FIG. 1, receive beamformer 12 provides an appropriate delay to the received digitized ultrasound echo signal so that the signals are combined in phase to produce an ultrasound beam. Generate line 22.

The dither signal source 208 is a common dither signal D.
And the dither signal is added to the adder 210 (this is the A / D
Via the (included in each channel immediately before the converter)
It is added to each received beam just prior to digitization by A / D converter 206. The dithering of the A / D converter enhances its ability to detect relatively low amplitude signals, thereby effectively increasing the dynamic range of the A / D converter. Such an increase is also useful while operating the equipment in PW Doppler mode (although it is particularly useful when operating the equipment in CW Doppler mode).

As is known to those skilled in the art familiar with AD converters, some dither signals cause extra special transitions in the LSB of the digital signal produced by A / D converter 206. LS depending on the dither signal source 208
A dither signal is provided having an amplitude that causes B to vary +/- 0.5 LSB. Average operating process (this is preferably at a point near the output of the signal processor)
(Which is described in connection with the boxcar filter of FIG. 4) results in a clear increase in the resolution of the A / D conversion.

In the preferred embodiment, the dither signal is caused to be a sine wave, and thus can be easily removed by a filter already present in the Doppler processor 18, such as a wall filter (discussed below). As such, the dither signal itself does not degrade the S / N ratio performance of the A / D converter, while the random noise dither signal does not
This will deteriorate the N-ratio performance.

In a preferred embodiment, the probe 6 has 120 transducer elements, where 64
Adjacent elements and channels of are used to transmit a focused and steered CW ultrasound beam (eg, at 4 mHz) into the patient's body, and the next 64 channels are focused CW Doppler beams (this Is steered to intersect the transmit beam at a predetermined depth within the patient body, as shown in FIG. 3).

According to the method (basic method) of the present invention, the user of the device can control the interface device 21,
For example, trackball (displayed in real time 2
Manipulation of viewing the 2D ultrasound image) may select the CW Doppler sensitive region 300 of the displayed image from which Doppler data is desired to be acquired. Once the region PW has been selected, the system controller 20 provides the appropriate delays to the transmit and receive beamformers 7, 12 so that the transmit (302) and receive (304) beams can be steered and preferably focused. , Which also overlap in the selected region, thereby obtaining Doppler data representing movement of the body in the volume. The acquisition of CW Doppler data is preferably carried out in time division multiplex with B-mode and / or color float images.

Since the transmit and receive beams are focused in the body to overlap with the same volume, the receive beamformer is much more sensitive than other volumes in the body. Therefore, such overlapping volumes are referred to as Doppler sensitive volumes (or when referred to as selected areas of a two-dimensional display of ultrasound images, they are referred to as Doppler sensitive). Not only is this technique significantly improved overcoming the position uncertainty (property) problem typically found in conventional CW Doppler imaging, but it is also easy to implement and easy for the operator to control.

In operation, the ultrasound device instrument is adapted to generate conventional B-mode images of blood vessels and / or other anatomical structures. At that time, the user operates a controllable device 21, such as a trackball, and "X" moves another marker to a region of interest in the blood vessel. The two arms of "X" represent the directions of the transmit and receive beams respectively in the selected area of interest. Therefore, the angle between the two beams of "X" varies according to the position of "X" relative to the transmit and receive apertures of the probe. Depending on the invention, the user may adjust the position of the probe and / or the position of the "X" marker,
Thereby, the CW Doppler angle can be optimized (at the same time,
Observe the anatomy (characteristics) of the blood vessel and the direction of the transmitted and received beams).

Additionally in accordance with a further aspect of the invention, the user may also adjust the focusing of one or both of the transmit and receive beams to better control the size of the selected Doppler region. As each change in focusing occurs, there will be a corresponding change in the size of the "X" displayed, the wider the focus, the larger the Doppler sensitive area and the larger the "X" displayed. “It gets bigger and bigger. The technique may maximize S / N ratio performance in a user-selectable volume within the body.

Thus, in accordance with the present invention, the system controller 20 operates the ultrasound system to make the steering angle and focus controllable for both transmit and receive beams in accordance with user selection of the Doppler sensitive region.

FIG. 4 shows the demodulator and Doppler processor portion of the ultrasound system shown in FIG. 1 configured by a system controller 20 for processing the CW Doppler signal and then generating Doppler data for display. More specifically, demodulator portion 14 is mixer 4
02, 404, the mixer having quadrature (signal) I and Q
Of the transmitted C to generate the demodulated Doppler signal of
It is excited by a quadrature sine wave signal having the frequency of the W Doppler ultrasonic wave signal. I and Q LPF filtering is conventionally required to remove the 2fo frequency components, and in this embodiment the LPF is configured as boxcar filters 406, 408, which are produced by mixers 402, 404, respectively. The accumulated digital signals are accumulated and decimated. As is well known to those of ordinary skill in the art of digital signal processing, boxcar filtering is essentially the accumulation or addition of digital samples, and then averaging by dividing the cumulative sum by the number of accumulated samples. And finally decimation, thereby producing a single multi-bit (ie 24 bits) at its output. In the present invention, 504 digital signal samples are used to generate each digital word output from the boxcar filter. Each digital word represents one of, for example, 128 points along a selected beamline.

The above I and Q outputs are applied to Doppler processor 18, which includes filtering of the I and Q signals using wall filters 410, 412 as is known to those skilled in the art, and As a method of acquiring the spectrum information, a function of adding the output of the wall filter to the FFT processor 414 is included. FFT processor 414 delivers a signal representing the frequency spectrum of its output 112 Doppler signal. The Doppler signal is applied to an audio speaker to "display" the Doppler data, or to a half of the video screen, thereby displaying the Doppler image beside the B-mode image. As is known, the wall filters 410, 412 may have HPFs that cut off unwanted relatively low frequencies, including the sinusoidal dither signal described above. Then, the FFT processor 414
The Doppler signal on the output side of is supplied to the Doppler display. The Doppler display has a video monitor and audio speakers to present Doppler information to the system operator.

The lengths of the boxcar filters 406 and 408 are set as follows: the boxcar length (accumulation interval) is set to have an integral multiple of the clutter signal / cycle number. That is, for example, the A / D converter sample rate is 36 mHz and the CW Doppler signal frequency is 4 mH.
If z, then 9XA / D samples / cycle of Doppler signal are obtained. Therefore, the number of samples averaged by the boxcar filter for determining each Doppler data point, ie the boxcar length, is an integer multiple of 9, eg 504 (which is 56 × 9). This is important because some clutter signals cause periodicity in the quantization error of the A / D converter, which may have the following amplitude due to the relatively high amplitude of the clutter signal. That is, it can have an amplitude that is on the order of magnitude greater than the amplitude of the Doppler signal that the device is trying to detect. By making the length of the boxcar filter an integer multiple of the ultrasonic frequency, the number of A / D samples / cycles, the echo is constant over the length of the boxcar and therefore the detection of low level Doppler signals. It will not interfere with you.

Thus, in the ultrasonic imaging apparatus satisfying all the purposes and the advantages obtained thereby, the CW
Novel methods and apparatus for controllably generating Doppler information are described. Many variations, modifications and other uses and applications (intended by the present subject matter) will be apparent to those of ordinary skill in the art after consideration of the specification and the accompanying drawings, which disclose advantageous embodiments thereof. become. For example, although the B-mode is described in the illustrated embodiment as being observed by the user to select the Doppler sensitive region, a color float image may also be used, or B
Overlap of both modal and color images may also be used. In addition, other shapes and sizes are "X"
It can be used as a marker equivalent, for example as a parallelogram with a dimension of controllable size. All such variations, modifications, variations and other uses and applications which do not depart from the simplicity of the invention may be covered by the requirements of the invention as defined by the claims.

[0030]

According to the present invention, a method of operating an ultrasonic imaging device using multiple elements-facilitating the use of a CW Doppler operating mode for an imaging device, and displaying two-dimensional ultrasonic waves. Enabling not only user control (method) for selecting CW Doppler sensitivity (sensitivity) region in an image, but also such user control (method) with a simple and low cost device cost The effect is that it can be realized by a method that can be easily controlled.

[Brief description of drawings]

FIG. 1 is a block diagram of an ultrasonic medical system in which the present invention may be used.

FIG. 2 is a block diagram of a front end portion of the ultrasonic medical system shown in FIG.

FIG. 3 shows how CW Doppler sensitive according to the scheme of the present invention using the apparatus of FIG.

4 is a block diagram of the demodulator and Doppler processor portion of the ultrasound system of FIG.

[Explanation of symbols]

 6 ultrasonic probe 7 beam former 8 preamplifier 10 A / D converter 12 reception beam former 14 demodulator 16 scan converter 18 Doppler processor 20 system controller 22 image delay circuit

Claims (15)

[Claims] 1. A method of operating an ultrasound imaging apparatus to acquire continuous wave (CW) Doppler data from a user selected area, comprising operating a multi-element transducer array and associated controllable delay and signal processing circuitry. Generating and displaying a two-dimensional ultrasound image in substantially real time, activating a device controllable by a user, and displaying at least one in real time in the displayed two-dimensional ultrasound image. A display of controllable position markers is provided to select one region of sensitivity in the ultrasound image for which it is desired to obtain CW Doppler data. , The operation of the multi-element transducer array and controllable delay and signal processing circuits described above. Based on the position of the area of sensitivity selected by the laser, whereby: 1) a steered beam of CW ultrasonic waves using a predetermined number of multiple elements; Transmit through a selected area of sensitivity, and 2) receive a steered receive beam that also passes through the selected area of sensitivity using a predetermined number of multiple elements. And processing the received beam to produce a Doppler image display, the display being representative of movement within a region of sensitivity selected by the user. Method of operating an imaging device. 2. The method of operating an ultrasonic imaging device for generating and displaying a B-mode image in the first (first) operating step. 3. The method of operating an ultrasonic imaging apparatus according to claim 1, wherein said first (first) operating step produces and displays a color flow image. 4. The method of operating an ultrasonic imaging apparatus according to claim 2, wherein said first (first) described operation step produces and displays a color flow image overlapping with said B-mode image. 5. In said third step, the multi-element and its associated delay and signal processing circuits are activated so that the transmitted steered beam is also selected by said user. The method of operating an ultrasonic imaging apparatus according to claim 1, wherein focusing is performed based on a position of a region of sensitivity. 6. In said third step, the multiple elements and their associated delay and signal processing circuits are activated so that the received steered beam is also selected by said user. The method of operating an ultrasonic imaging apparatus according to claim 5, wherein focusing is performed based on the position of a region of sensitivity. 7. In said third step, the multiple elements and their associated delay and signal processing circuits are activated so that the transmitted steered beam is also selected by said user. The method of operating an ultrasonic imaging apparatus according to claim 1, wherein focusing is performed based on a position of a region of sensitivity. 8. The controllable position marker displayed upon activation of the user-controllable device has at least one "X", wherein:
2. The method of operating an ultrasonic imaging apparatus according to claim 1, wherein each arm of "X" represents each of transmitting and receiving beam directions based on a position of a sensitivity region selected by a user. 9. In the operation of the user-controllable device, the controllable displayed position marker has a parallelogram box shape equivalent to "X", wherein the box is a transmit / receive beam. The ultrasonic imaging device according to claim 1, which represents a size of a region (area) selected by a user, which is defined by focusing and steering. 10. An ultrasonic imaging apparatus for acquiring continuous wave (CW) Doppler data from a region of a body to be inspected selected by a user, comprising a multi-element ultrasonic transducer array, the ultrasonic transducer array being coupled to the array. And into the body, and
There is a delay circuit for controlling the steering of a transmitting and receiving beam of ultrasonic energy from there, and a signal processing circuit connected to the delay circuit for generating an image signal in response to the received beam. A display device connected to the signal processing circuit for displaying a two-dimensional ultrasonic image of a portion of the body to be examined in substantially real time in response to an image signal, A user controllable device for controllably locating at least one position marker connected to the display, the marker being substantially real-time within the displayed two-dimensional ultrasound image. And the marker selects a region of sensitivity in the ultrasound image for which it is desired to obtain CW Doppler data. Is positioned by the user and is connected to the delay circuit and is responsive to the user's selection of the position of the Doppler sensitivity via the device controllable by the user to: Control means of: 1) causing a predetermined number of said multiple elements to transmit a steered beam of CW ultrasonic energy through said region of sensitivity selected by said user; ) Doing a predetermined number of the multiple elements of the array,
An ultrasonic imaging device configured to receive a steered receive beam of ultrasonic energy passing through a region of sensitivity selected by a user. 11. The ultrasonic imaging apparatus according to claim 10, wherein the delay circuit is also connected to the array for controlling focusing of at least one of transmission and reception beams. 12. The delay circuit processes the receive beam, wherein a delay signal is generated to produce a Doppler signal that causes a Doppler image representing motion within a region of user-selected sensitivity to be displayed on the display. The ultrasonic imaging apparatus according to claim 10, wherein the ultrasonic imaging apparatus is processed as follows. 13. The user-controllable device causes the controllable position marker to be displayed as at least one "X", wherein:
Each arm of the "X" is representative of one of the transmit and receive beam directions based on the position of the area selected by the user as controlled by a device controllable by the user. 10. The ultrasonic imaging apparatus according to 10. 14. The user-controllable device causes the controllable position marker to be displayed as a parallelogram box, wherein the box is controlled by the user-controllable device. 11. The ultrasonic imaging apparatus according to claim 10, wherein each of the transmitting and receiving beam directions is represented based on the position of the area selected by the user. 15. The user controllable device is connected to the display device, and the size of the displayed controllable position marker is selected by the user by steering and / or focusing of the transmit and receive beams. The ultrasonic imaging apparatus according to claim 10, wherein the ultrasonic imaging apparatus is changed according to the size of a region to be covered.