JP2005288021A - Ultrasonic diagnostic apparatus, and its diagnosing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the flicker of an image which is acquired in ultrasonic image diagnosis, and to reduce the blur of the image. <P>SOLUTION: An ultrasonic diagnostic apparatus comprises: an ultrasonic probe 32 for transmitting ultrasonic wave into the inspection part of a subject and receiving echoes which are returned after reflection; a receiving circuit 33 for receiving an electric signal from the ultrasonic probe 32 and converting the signal into a receiving circuit output signal s1; an inter-frame filter 34 for passing the high frequency component of the signal from the receiving circuit 32 and converting it into a filter output signal s2; a coefficient setting means 43 for setting a desired synthesis rate; a synthesizing means 35 for synthesizing the receiving circuit output signal s1 with the filter output signal s2 by the desired synthesis rate and performing conversion into a synthetic output signal s3; an image generating means 39 having a detector 36 for wave-detecting the amplitude of the synthetic output signal from the synthesizing means 35 and a logarithm compressor 38 for generating image data from a reception signal from the detector 36; and a display unit 40 for displaying the image from the image data. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an ultrasonic diagnostic apparatus that generates and displays an ultrasonic image based on phase information and amplitude information included in a reception signal obtained by scanning a cross section of a subject with ultrasonic waves, and a diagnostic method thereof. is there.

  In specific ultrasound imaging diagnosis, it is desired to suppress areas where the motion or movement speed is relatively slow, such as the chest wall, ribs and myocardium, and to emphasize only areas where the movement or movement speed is relatively fast, such as the heart wall. It was.

  FIG. 8 is a block diagram showing a configuration of a conventional ultrasonic diagnostic apparatus.

  FIG. 8 shows a conventional ultrasonic diagnostic apparatus 1, which includes a transmission circuit 2, an ultrasonic probe (probe) 3 that receives an echo reflected and returned, and this A receiving circuit 4 that receives an electric signal from the ultrasonic probe 3, an inter-frame filter circuit 5 that receives an electric signal from the receiving circuit 4, and an electric signal from the receiving circuit 4 or the inter-frame filter circuit 5 An amplitude detector 6, a logarithmic compressor 7 that creates image data of a B-mode image, and a display unit 8 that displays an image are provided.

  The detector 6 can receive an electrical signal from the receiving circuit 4 or from the inter-frame filter circuit 5 by switching the SW (switch) according to a command from the system controller 11 (for example, Patent Literature 1). 1).

  When the two-dimensional tomographic image (frame) is intermittently generated / displayed by the inter-frame filter circuit 5, an HPF (High Pass Filter) is used by using a received signal including both amplitude information and phase information. To perform filtering between frames.

  By using the inter-frame filter circuit 5, it is possible to suppress an examination site with a relatively slow motion or movement speed and emphasize and display an examination site with a relatively fast motion or movement speed. In the ultrasonic diagnostic apparatus 1, the filter characteristics of the inter-frame filter circuit 5 can be selected according to the movement or moving speed of the examination site.

  Further, after the signal processing in the logarithmic compressor 7, the amplitude signal is filtered by an LPF (Low Pass Filter) between frames to smooth the generated image.

Furthermore, by designating a region of interest (ROI), an examination site with a relatively fast motion or movement speed is emphasized within the ROI, and normal data is output outside the ROI, so that the movement or movement speed is increased. A relatively slow examination site can be observed.
JP-A-8-107896 (pages 3-6, FIGS. 1 and 8)

  However, in the ROI, instead of emphasizing an examination site having a relatively fast motion or movement speed, an examination site having a relatively slow motion or movement speed, which should originally exist, also disappears at the same time. Therefore, even when the filter characteristics are changed with time according to the time phase of pulsation, flickering occurs near the examination site where the motion or movement speed in the image is relatively slow. Image flickering is a burden on the operator.

  In addition, the inter-frame smoothing after detection and logarithmic compression can reduce to some extent the flicker near the examination site where the motion or movement speed in the image is relatively slow, but conversely, the image of the examination site where the movement or movement speed is relatively fast Becomes blurry.

  Furthermore, the operator needs to perform an operation of setting the position of the ROI in accordance with an examination site having a relatively fast motion or movement speed and an examination site having a relatively slow motion or movement speed.

  The present invention has been made in consideration of the above-described circumstances, and an object thereof is to provide an ultrasonic diagnostic apparatus and a diagnostic method thereof that can reduce flickering of an image and reduce blurring of an image.

  Another object of the present invention is to provide an ultrasonic diagnostic apparatus and a diagnostic method thereof that can improve operability without the need to set a region of interest in advance of diagnosis.

  In order to solve the above-described problem, an ultrasonic diagnostic apparatus according to the present invention transmits a transmission circuit that outputs an ultrasonic transmission signal, and transmits the ultrasonic wave into an examination site of the subject by inputting the transmission signal. An ultrasonic probe that receives echoes that are reflected back, a receiving circuit that receives an electrical signal from the ultrasonic probe and converts it into a receiving circuit output signal, and a high-frequency signal from the receiving circuit An inter-frame filter that passes the component and converts it into a filter output signal; coefficient setting means for setting a required synthesis ratio; and the received circuit output signal and the filter output signal that are synthesized at the required synthesis ratio and synthesized output Combining means for converting into signals, image generating means for generating B-mode image data from the combined output signal from the combining means, and a display unit for displaying B-mode image images from the image data. It was.

  In order to solve the above-described problems, an ultrasonic diagnostic method according to the present invention receives an electrical signal from an ultrasonic probe and converts it into a reception circuit output signal, while converting the reception circuit output signal into a filter output signal. In the ultrasonic diagnostic method for generating the B-mode image data from the reception circuit output signal or the filter output signal and displaying the B-mode image image, the reception circuit at the time of diagnosis A diagnostic pre-synthesis ratio setting step in which a synthesis ratio between the output signal and the filter output signal is set, and a diagnosis pre-synthesis ratio storage in which a plurality of synthesis ratios set in the synthesis ratio setting step are saved in advance of diagnosis A reception circuit output signal reception step in which the reception circuit output signal is received during diagnosis, a filter output signal reception step in which the filter output signal is received, and the plurality From the synthesis ratio, the required synthesis ratio is selected and set, and the reception circuit output signal and the filter output signal are respectively set in the required synthesis ratio setting step selected in the required synthesis ratio selection step. Weighting step weighted, respective output signals weighted in the weighting step are combined and converted into a combined output signal, image data is acquired based on the combined output signal, and an image is displayed And an image display step.

  The ultrasonic diagnostic method according to the present invention receives an electrical signal from an ultrasonic probe and converts it into a reception circuit output signal, while converting the reception circuit output signal into a filter output signal, In an ultrasonic diagnostic method for generating B-mode image data from an output signal or the filter output signal and displaying the B-mode image, required synthesis of the reception circuit output signal and the filter output signal at the time of diagnosis A required coefficient input process in which a ratio is input; a required coefficient setting process in which the required composite ratio is set; a reception circuit output signal reception process in which the reception circuit output signal is received at the time of diagnosis; and the filter output signal The received circuit output signal and the filter output signal at the required synthesis ratio set in the received filter output signal receiving step and the required coefficient setting step. Each weighted weighting step, each output signal weighted in the weighting step is synthesized, a synthesis step converted into a synthesized output signal, and image data is acquired based on the synthesized output signal, An image display step in which an image is displayed.

  According to the ultrasonic diagnostic apparatus and the diagnostic method of the present invention, it is possible to reduce the flicker of the image and to reduce the blur of the image.

  Further, according to the ultrasonic diagnostic apparatus and the diagnostic method thereof according to the present invention, it is not necessary to set a region of interest in advance of diagnosis, and operability can be improved.

  Embodiments of an ultrasonic diagnostic apparatus and a diagnostic method thereof according to the present invention will be described with reference to the accompanying drawings.

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

  FIG. 1 shows an ultrasonic diagnostic apparatus 20. In this ultrasonic diagnostic apparatus 20, a transmission circuit 31 that outputs an ultrasonic transmission signal and a transmission signal are input to transmit ultrasonic waves into the examination site of the subject. An ultrasound probe (probe) 32 that transmits and receives echoes reflected and returned; a reception circuit 33 that receives an electrical signal from the ultrasound probe 32 and converts it into a reception circuit output signal s1; An inter-frame filter 34 for converting the digital reception circuit output signal s1 from the reception circuit 33 into a filter output signal s2 by attenuating a low frequency component from a time change (time signal) and passing a high frequency component, and a reception circuit output signal s1 and the filter output signal s2 are combined at a required combining ratio and converted into a combined output signal s3, a detector 36 as a detecting unit for detecting the amplitude of the combined output signal s3, and the detection An image generation means 39 having a logarithmic compressor 38 as a logarithmic compression means for creating B-mode image data from the received signal from 36, and a B-mode image which is a tomographic image of tissue distribution from the image data are displayed. A display unit 40 is provided.

  Although not shown, the transmission circuit 31 includes a clock oscillator that generates a clock pulse, a frequency divider that divides the clock pulse generated by the clock oscillator into a predetermined frequency, for example, a 6 kHz rate pulse, A distributor that distributes rate pulses into the number of channels, a transmission delay circuit that gives different delay times to the rate pulses for each channel, and a pulser that applies a pulse voltage to the piezoelectric elements of the corresponding channels at the timing of receiving the rate pulses. And are provided.

  At the tip of the ultrasonic probe 32, a plurality of piezoelectric elements (not shown) that reversibly convert mechanical vibrations and electrical signals are centrally arranged and equipped. The ultrasonic probe 32 is connected to the transmission circuit 31 during transmission, and is connected to the reception circuit 33 during reception.

  Although not shown, the reception circuit 33 corresponds to a preamplifier that amplifies an electric signal for each channel and an analog electric signal of each amplified channel corresponding to a required interval, for example, an interval of 0.5 mm, with respect to one scanning line. An A / D converter that samples at a sampling frequency to be converted into a digital signal at each sampling point, a reception delay circuit that gives different delay times to the digital signal for each channel, and an adder that adds the digital signal of each channel All are provided as linear circuits.

  The inter-frame filter 34 is configured by an FIR (Finite Impulse Response) type or IIR (Infinite Impulse Response) type HPF (High Pass Filter), which is a high-pass digital filter, and includes a filter controller.

  FIG. 2 is a block diagram showing the configuration of the synthesizing means 35. As shown in FIG.

  The weighting unit 35 shown in FIG. 2 weights the receiving circuit output signal s1 directly received from the receiving circuit 33 and the filter output signal s2 received from the receiving circuit 33 via the inter-frame filter 34 with a required combining ratio. A weighting unit 35a serving as a weighting unit and a combining unit 35b that combines the output signals weighted by the weighting unit 35a are provided.

  Further, as the detector 36 shown in FIG. 1, a non-linear square detection method is adopted.

Logarithmic compressor 38, for example 2 ²⁰ relatively narrow circuit on the dynamic range of the dynamic range of the received signal, is substantially compressed into a relatively narrow dynamic range that can be handled by the display unit 40, and reflected on the tissue distribution B Create image data of the mode image.

  Further, the ultrasonic diagnostic apparatus 20 includes a system controller 42 for inputting an ECG synchronization signal s4 related to the subject measured by an ECG (Electro Cardio Gram) sensor 41, coefficient setting means 43 for setting a required synthesis ratio, an operator Is input to the inter-frame filter 43 and the coefficient setting means 43 through the system controller 42.

  The console 45 is provided with a filter selection characteristic switch for an operator to select a filter characteristic of the inter-frame filter 34, and a combination ratio input means 45a such as a button for manually inputting a required combination ratio.

  A filter controller (not shown) included in the inter-frame filter 34 detects the ECG synchronization signal s4. The filter controller selects a high cutoff frequency in the systole where the movement or movement speed of the examination site is relatively fast from the interval of the R wave, while lowering in the diastole where the movement or movement speed of the examination site is relatively slow. Select the frequency.

  Note that a low-pass filter (LPF) may be provided between the logarithmic compressor 38 and the display unit 40 or between the detector 36 and the logarithmic compressor 38. In that case, the image data after nonlinear processing is filtered between frames by a low-pass filter.

  Next, an ultrasonic diagnostic method using the ultrasonic diagnostic apparatus 20 will be described with reference to the flowchart shown in FIG.

  At the time of diagnosis, the receiving circuit output signal s1 and the filter output signal s2 are respectively received and synthesized by the synthesizing unit 35 of the ultrasonic diagnostic apparatus 20. First, the receiving circuit output signal s1 and the filter output signal s2 are preliminarily diagnosed. (Weighting coefficient C: weighting coefficient D) is set (step S1), and a plurality of composition ratios are stored in the coefficient setting means 43 (step S2).

For example, the weighting coefficient C weighted to the reception circuit output signal s1 in the combination ratio is the coefficient c ₁ of the position unit in the depth (distance) direction of the two-dimensional tomographic image, the coefficient c ₂ of the position unit in the scanning line direction, and is set is calculated by at least one of the required coefficient c of coefficients c ₃ time units. On the other hand, for example, the weighting coefficient D weighted to the filter output signal s2 is the coefficient d ₁ of the position unit in the depth direction of the two-dimensional tomogram, the coefficient d ₂ of the position unit in the scanning line direction, and the coefficient d _{3 of the} time unit. Is calculated and set by at least one required coefficient d. Hereinafter, a method for calculating the composition ratio by adding all the positions in the depth direction of the two-dimensional tomogram, the positions in the scanning line direction, and the time will be described.

FIG. 4 is a graph showing an example of the coefficients c ₁ and d ₁ at positions in the depth direction of the two-dimensional tomographic image.

The upper part of FIG. 4 shows the coefficient c ₁ (c ₁ <1) with respect to the position in the depth direction of the two-dimensional tomogram for calculating the weighting coefficient C as a graph, while the lower part calculates the weighting coefficient D. Therefore, the coefficient d ₁ (d ₁ = 1−c ₁ ) with respect to the depth direction of the two-dimensional tomographic image is shown as a graph.

In the graph shown in the upper and lower stages of FIG. 4, while the depth of the two-dimensional tomographic image is relatively shallow, for example, “c ₁ = 0.1” and “d ₁ = 0.9” are set, while the two-dimensional tomographic image is set. For example, “c ₁ = 0.9” and “d ₁ = 0.1” are set at positions where the depth of is relatively deep. Furthermore, the coefficients c ₁ and d ₁ of the position where the depth of the two-dimensional tomographic image is sandwiched between a relatively shallow position and a deep position are, for example, the shallow position coefficients c ₁ and d ₁ and the deep position coefficients c ₁ and d ₁ . d ₁ is set to be connected to each other.

FIG. 5 is a graph showing an example of the coefficients c ₂ and d ₂ at positions in the scanning line direction.

The upper part of FIG. 5 shows the coefficient c ₂ (c ₂ <1) with respect to the scanning line direction for calculating the weighting coefficient C as a graph, while the lower part shows the coefficient c _{2 with} respect to the scanning line direction for calculating the weighting coefficient D. The coefficient d ₂ (d ₂ = 1−c ₂ ) is shown as a graph.

Figure In the graph shown in the lower top 5, the position of the central scanning line, for example, while being set as "c _{2 =} 0.1" and "d _{2 =} 0.9", the position of the scanning lines across, for example, "c ₂ = 0.9 "and" d ₂ = 0.1 ". Furthermore, the scanning line central factor from the position of the position sandwiched between the positions of both ends c _2, d _2, for example, the coefficient of the position of the central scanning line c _2, d ₂ and the scanning lines coefficient c ₂ position at both ends, It is set so as to connect d ₂ and, respectively.

FIG. 6 is a graph showing an example of the coefficients c ₃ and d ₃ in time.

The upper part of FIG. 6 shows the coefficient c ₃ (c ₃ <1) with respect to time for calculating the weighting coefficient C as a graph, while the lower part shows the coefficient d ₃ for the time series for calculating the weighting coefficient D. (D ₃ = 1−c ₃ ) is shown as a graph.

In the graph shown in the upper and lower stages of FIG. 6, for example, “c ₃ = 0.1” and “d ₃ = 0.9” are set in a part of the systole, while in the part of the diastole, for example, “c ₃ = 0.9 "and" d ₃ = 0.1 "are set. Further, the coefficient c _3, d ₃ sandwiched between a minute diastolic Some systole coefficient systolic c _3, d ₃ and coefficient of diastolic c _3, d ₃ and a so as to connect each Is set.

Incidentally, FIG. 4, in the graph shown in FIGS. 5 and 6, the position in the depth direction, the coefficient c ₁ to c _3, the coefficient d ₁ to d ₃ is set linearly with respect to the position and time of the scanning line direction However, it can also be set in a curvilinear manner.

The weighting coefficient C weighted to the receiving circuit output signal s1 is
[Equation 1]
Weighting coefficient C = (c ₁ + c ₂ + c ₃ ) / (c ₁ + c ₂ + c ₃ + d ₁ + d ₂ + d ₃ )
...... (1)
On the other hand, the weighting coefficient D weighted to the filter output signal s2 is
[Equation 2]
Weighting coefficient D = (d ₁ + d ₂ + d ₃ ) / (c ₁ + c ₂ + c ₃ + d ₁ + d ₂ + d ₃ )
(2)
Is calculated by

As shown in the graph shown in the upper and lower sections of FIG. 4, the relatively shallow position where the relatively low frequency fixed echo appears is set as “c ₁ = 0.1” and “d ₁ = 0.9”. From 1) and (2), the weighting coefficient D increases, and the filter output signal s2 from which the low-frequency component has been removed is emphasized. On the other hand, the relatively deep position where the examination site such as the myocardium where the motion or movement speed is relatively slow appears as “c ₁ = 0.1” and “d ₁ = 0.9”, so that the weighting coefficient C becomes large and low. The reception circuit output signal s1 including the frequency component is emphasized.

As shown in the upper and lower graphs of FIG. 5, the positions of the center of the scanning line where the examination site such as the heart wall where the motion or movement speed is relatively fast appear are “c ₂ = 0.1” and “d ₂ = 0.9”. By setting, the weighting coefficient D is increased from the equations (1) and (2), and the filter output signal s2 from which the low frequency component is removed is emphasized. On the other hand, by setting the positions of both ends of the scanning line where the examination site such as the myocardium where the motion or movement speed is relatively low appear as “c ₂ = 0.1” and “d ₂ = 0.9”, the weighting coefficient C increases, The reception circuit output signal s1 including the low frequency component is emphasized.

As shown in the graph shown in the upper and lower sections of FIG. 6, the systole having a relatively fast motion or moving speed is set as “c ₃ = 0.1” and “d ₃ = 0.9”, so that the formula (1) and From (2), the weighting coefficient D increases, and the filter output signal s2 from which the low-frequency component has been removed is emphasized. On the other hand, by setting the expansion period in which the movement or movement speed is relatively low as “c ₃ = 0.1” and “c ₃ = 0.9”, the weighting coefficient C increases and the reception circuit output signal s1 including the low frequency component Is emphasized.

Here, for example, when “c ₁ = 0.1” in FIG. 4 where the depth direction is shallow, and when “c ₂ = 0.9” at the left end of FIG. 5 in the scanning line direction, and in FIG. In the case of “c ₃ = 0.1”, the weighting coefficient C weighted to the reception circuit output signal s1 is expressed by the following equation (1):
[Equation 3]
Weighting coefficient C = (0.1 + 0.9 + 0.1) / (0.1 + 0.9 + 0.1 + 0.9 + 0.1 + 0.9)
= 0.55 (1A)
Is calculated.

Further, for example, in the case of “c ₁ = 0.9” where the depth direction is shallow in FIG. 4 and the scanning line direction is “c ₂ = 0.1” at the left end in FIG. In the case of “c ₃ = 0.9”, the weighting coefficient D weighted to the filter output signal s2 is calculated from the equation (2):
[Equation 4]
Weighting coefficient D = (0.9 + 0.1 + 0.9) / (0.1 + 0.9 + 0.1 + 0.9 + 0.1 + 0.9)
= 0.45 (2A)
Is calculated. Therefore, the composition ratio (weighting coefficient C: weighting coefficient D = 0.55: 0.45) is calculated.

  The weighting coefficients C and D are calculated in equations (1) and (2) so that the sum is “1”, but the sum of the weighting coefficients C and D is “1”. The case is not limited.

  Subsequently, at the time of diagnosis, the transmission circuit 31 of the ultrasonic diagnostic apparatus 20 shown in FIG. 1 scans the ultrasonic probe 32 and transmits ultrasonic waves from the ultrasonic probe 32 into the examination region of the subject. Is done. An echo signal reflected and returned from the examination site is received by a piezoelectric element (not shown) of the ultrasonic probe 32 and converted into an electric signal (voltage signal). The electric signal of the piezoelectric element is received by the receiving circuit 33 for each channel.

  In the receiving circuit 33, the electric signal is amplified for each channel by a preamplifier (not shown), and the amplified analog electric signal of each channel is digitally converted by an A / D converter (not shown). A digital signal is given a different delay time for each channel by a reception delay circuit (not shown), and is added by an adder (not shown). As a result, a reception signal in which a reflection component from a specific direction is emphasized is obtained. This received signal includes amplitude information that reflects the difference in acoustic impedance between tissues, and phase information that reflects the movement (movement or movement speed) of the examination site.

  The reception signal including the amplitude information and the phase information is received as the reception circuit output signal s1 from the reception circuit 33 to the synthesis unit 35 (step S3).

  On the other hand, a reception circuit output signal s1 including amplitude information and phase information output from the reception circuit 33 is received by an interframe filter 34 formed of a high-pass filter of FIR type or IIR type. . The inter-frame filter 34 attenuates the low frequency part from the time change with respect to the same coordinate between a plurality of two-dimensional tomographic images (frames).

  Here, the inter-frame filter 34 detects the ECG synchronization signal s 4 from the ECG sensor 41 via the system controller 42. In the filter controller of the inter-frame filter 34, from the interval of the R wave, the cut-off frequency is high in the systole when the movement or movement speed of the examination site is relatively fast, and the cut-off frequency is low in the relatively slow diastole. A filter coefficient is selected. In the filter controller of the inter-frame filter 34, the filter coefficient of the inter-frame filter 34 may be selected according to the motion speed of the examination site.

  The signal including the amplitude information and the phase information is received as the filter output signal s2 from the interframe filter 34 by the synthesizing unit 35 (step S4).

  In the synthesizing unit 35, a required synthesis ratio is selected and set for each sample from a plurality of synthesis ratios stored in the coefficient setting unit 43 in advance in step S2 (step S5). The selection of the required composition ratio in step S5 is automatically performed according to parameters such as the heart rate and the size of the examination site.

  The reception circuit output signal s1 and the filter output signal s2 are weighted with the required synthesis ratio selected in step S5 (step S6).

  That is, the receiving circuit output signal s1 received directly from the receiving circuit 33 by the weighting unit 35a of the synthesizing unit 35 shown in FIG. 2 is a weighting coefficient C, for example, “0.55” calculated by the equation (1A). Weighted. On the other hand, the filter output signal s2 received from the receiving circuit 33 via the interframe filter 34 is weighted with a weighting coefficient D, for example, “0.45” calculated by the equation (2A). Note that the weighting in step S6 is performed independently for each sample.

  As described above, the weighting unit 35a of the synthesizing unit 35 receives the reception circuit output signal s1 and the reception circuit output signal s1 at the required synthesis ratio calculated by adding the position in the depth direction, the position in the scanning line direction, and the time of the two-dimensional tomogram. The filter output signal s2 is weighted.

  The respective output signals weighted by the weighting unit 35a are received by the synthesizing unit 35b and synthesized by the synthesizing unit 35b (step S7).

  The signal synthesized by the synthesizer 35b is received as a synthesized output signal s3 from the synthesizer 35b to the detector 36 shown in FIG. In this detector 36, the amplitude of the received signal is detected and sent to a logarithmic compressor 38.

  In the logarithmic compressor 38, the dynamic range of the received signal is compressed to a dynamic range on a circuit that is relatively narrow, and substantially to a relatively narrow dynamic range that can be handled by the display unit 40. Then, B-mode image data reflecting the tissue distribution is generated. This image data is sent to the display unit 40.

  On the display unit 40, the image data is visually displayed as a B-mode image in a shaded manner (step S8).

  When a low-pass filter is provided between the logarithmic compressor 38 and the display unit 40, the image data after nonlinear processing is filtered between frames by the low-pass filter. Therefore, it is possible to simultaneously achieve attenuation of a relatively low frequency fixed echo component by the inter-frame filter 3 and image smoothing by the low-pass filter.

  Further, when a low-pass filter is provided between the detector 36 and the logarithmic compressor 38, noise of amplitude information generated at the output of the inter-frame filter 34 is suppressed, and image flicker is suppressed.

  According to the ultrasonic diagnostic apparatus 20 and the ultrasonic diagnostic method according to the present invention, by combining the reception circuit output signal s1 and the filter output signal s2 at a preset required synthesis ratio, the target motion or movement speed can be obtained. It is possible to emphasize a relatively fast examination site and to suppress fixed noise data with a relatively slow motion or movement speed, so that it is possible to reduce image flicker and image blur.

  In addition, according to the ultrasonic diagnostic apparatus 20 and the ultrasonic diagnostic method according to the present invention, it is not necessary to set a region of interest in advance of diagnosis by automatically selecting a required synthesis ratio, thereby improving operability. be able to.

  Next, a modified example of the ultrasonic diagnostic method using the ultrasonic diagnostic apparatus 20 will be described using the flowchart shown in FIG.

  The apparatus configuration of this modification is the same as that of the ultrasonic diagnostic apparatus 20 shown in FIG.

  First, the operator inputs the required synthesis ratio for each sample to the synthesis ratio input means 45a of the console 45 (step S11), and the coefficient setting means 43 sets the required synthesis ratio (step S12).

For example, in order to calculate the weighting coefficient C weighted to the reception circuit output signal s1 among the required synthesis ratio, the coefficient c ₁ of the position unit in the depth (distance) direction of the two-dimensional tomographic image described in step S1; At least one required coefficient c of the position unit coefficient c _{2 in} the scanning line direction and the time unit coefficient c ₃ is input.

On the other hand, for example, in order to calculate the weighting factor D is weighted in the filter output signal s2, the two-dimensional coefficients d ₁ position unit in the depth direction of the tomographic _image, the coefficient d _2, and the time unit of the position unit of the scanning line direction At least one required coefficient c of the coefficient d ₃ is input. Hereinafter, a case where the depth direction position, the scanning line direction position, and the time of the two-dimensional tomographic image are all input will be described.

The coefficient setting unit 43, and the coefficients _c 1 _{to c 3,} d 1 to d ₃ input in step S11 based on, from equation (1) and (2), the required synthesis ratio in near real-time is calculated and set Is done.

  The input of the required coefficient c in step S11 and the setting of the composition ratio in step S12 may be performed in advance of diagnosis or may be performed at the time of diagnosis.

  Subsequently, at the time of diagnosis, the transmission circuit 31 of the ultrasonic diagnostic apparatus 20 shown in FIG. 1 scans the ultrasonic probe 32 and transmits ultrasonic waves from the ultrasonic probe 32 into the examination region of the subject. Is done. An echo signal reflected and returned from the examination site is received by a piezoelectric element (not shown) of the ultrasonic probe 32 and converted into an electric signal (voltage signal). The electric signal of the piezoelectric element is received by the receiving circuit 33 for each channel.

  In the receiving circuit 33, the electric signal is amplified for each channel by a preamplifier (not shown), and the amplified analog electric signal of each channel is digitally converted by an A / D converter (not shown). A digital signal is given a different delay time for each channel by a reception delay circuit (not shown), and is added by an adder (not shown). As a result, a reception signal in which a reflection component from a specific direction is emphasized is obtained. This received signal includes amplitude information that reflects the difference in acoustic impedance between tissues, and phase information that reflects the movement (movement or movement speed) of the examination site.

  The reception signal including the amplitude information and the phase information is received as the reception circuit output signal s1 from the reception circuit 33 to the synthesis unit 35 (step S3).

  On the other hand, a reception circuit output signal s1 including amplitude information and phase information output from the reception circuit 33 is received by an interframe filter 34 formed of a high-pass filter of FIR type or IIR type. . The inter-frame filter 34 attenuates the low frequency part from the time change with respect to the same coordinate between a plurality of two-dimensional tomographic images (frames).

  Here, the inter-frame filter 34 detects the ECG synchronization signal s 4 from the ECG sensor 41 via the system controller 42. In the filter controller of the inter-frame filter 34, from the interval of the R wave, the cut-off frequency is high in the systole when the movement or movement speed of the examination site is relatively fast, and the cut-off frequency is low in the relatively slow diastole. A filter coefficient is selected. In the filter controller of the inter-frame filter 34, the filter coefficient of the inter-frame filter 34 may be selected according to the motion speed of the examination site.

  The signal including the amplitude information and the phase information is received as the filter output signal s2 from the interframe filter 34 by the synthesizing unit 35 (step S4).

  The reception circuit output signal s1 and the filter output signal s2 are respectively weighted with the required synthesis ratio set in step S12 (step S6).

  That is, the receiving circuit output signal s1 received directly from the receiving circuit 33 by the weighting unit 35a of the synthesizing unit 35 shown in FIG. 2 is a weighting coefficient C, for example, “0.55” calculated by the equation (1A). Weighted. On the other hand, the filter output signal s2 received from the receiving circuit 33 via the interframe filter 34 is weighted with a weighting coefficient D, for example, “0.45” calculated by the equation (2A). Note that the weighting in step S6 is performed independently for each sample.

  As described above, the weighting unit 35a of the synthesizing unit 35 uses the reception circuit output signal s1 and the filter at the required synthesis ratio calculated by adding the position in the depth direction, the position in the scanning line direction, and the time of the two-dimensional tomographic image. The output signal s2 is weighted.

  The respective output signals weighted by the weighting unit 35a are received by the synthesizing unit 35b and synthesized by the synthesizing unit 35b (step S7).

  The signal synthesized by the synthesizer 35b is received as a synthesized output signal s3 from the synthesizer 35b to the detector 36 shown in FIG. In this detector 36, the amplitude of the received signal is detected and sent to a logarithmic compressor 38.

  In the logarithmic compressor 38, the dynamic range of the received signal is compressed to a dynamic range on a circuit that is relatively narrow, and substantially to a relatively narrow dynamic range that can be handled by the display unit 40. Then, B-mode image data reflecting the tissue distribution is generated. This image data is sent to the display unit 40.

  On the display unit 40, the image data is visually displayed as a B-mode image in a shaded manner (step S8).

  When a low-pass filter is provided between the logarithmic compressor 38 and the display unit 40, the image data after nonlinear processing is filtered between frames by the low-pass filter. Accordingly, it is possible to simultaneously achieve attenuation of a relatively low frequency fixed echo component by the inter-frame filter 34 and smoothing of the image by the low-pass filter.

  Further, when a low-pass filter is provided between the detector 36 and the logarithmic compressor 38, noise of amplitude information generated at the output of the inter-frame filter 34 is suppressed, and image flicker is suppressed.

  According to the modification of the ultrasonic diagnostic apparatus 20 and the ultrasonic diagnostic method according to the present invention, the reception circuit output signal s1 and the filter output signal s2 are obtained at a required synthesis ratio calculated and set almost in real time by the input required coefficient. By synthesizing, it is possible to emphasize the target inspection or movement speed that is relatively fast, and to suppress fixed noise data with relatively low movement or movement speed, so that flickering of the image can be reduced and the image can be reduced. Can reduce blur.

  Further, according to the modification of the ultrasonic diagnostic apparatus 20 and the ultrasonic diagnostic method according to the present invention, it is necessary to input and change the required synthesis ratio by a relatively simple operation, and to set the region of interest in advance of diagnosis. The operability can be improved.

1 is a block diagram showing the configuration of an embodiment of an ultrasonic diagnostic apparatus according to the present invention. The block diagram which shows the structure of a synthetic | combination means. The flowchart which shows the ultrasonic diagnostic method which concerns on this invention. The graph which shows an example of the coefficient in the position of the depth direction of a two-dimensional tomogram. The graph which shows an example of the coefficient in the position of a scanning line direction. The graph which shows an example of the coefficient in time. The flowchart which shows the modification of the ultrasonic diagnosing method which concerns on this invention. The block diagram which shows the structure of the conventional ultrasonic diagnostic apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 20 Ultrasonic diagnostic apparatus 31 Transmission circuit 32 Ultrasonic probe 33 Transmission circuit 34 Interframe filter 35 Synthesis | combination means 35a Weighting part 35b Synthesis | combination part 36 Detector 38 Logarithmic compressor 39 Image generation means 40 Display unit 43 Coefficient setting means 45 Console 45a Composite ratio input means

Claims (9)

A transmission circuit for outputting an ultrasonic transmission signal;
An ultrasonic probe that receives the echo that is transmitted and reflected back by transmitting the ultrasonic wave into the examination region of the subject by inputting the transmission signal;
A receiving circuit that receives an electrical signal from the ultrasonic probe and converts it into a receiving circuit output signal; and
An inter-frame filter that passes a high-frequency component of the signal from the receiving circuit and converts it into a filter output signal;
Coefficient setting means for setting the required synthesis ratio;
Synthesizing means for synthesizing the reception circuit output signal and the filter output signal at the required synthesis ratio and converting them to a synthesized output signal;
Image generating means for generating image data of a B-mode image from the combined output signal from the combining means;
An ultrasonic diagnostic apparatus comprising: a display unit that displays a B-mode image from the image data. The synthesizing means includes weighting means for weighting the reception circuit output signal and the filter output signal by the required synthesis ratio, respectively, and synthesizes the output signals from the weighting means to convert them into a synthesized output signal. The ultrasonic diagnostic apparatus according to claim 1, wherein the apparatus is an ultrasonic diagnostic apparatus. The image generating means includes a detecting means for detecting the amplitude of the combined output signal from the combining means, and a logarithmic compression means for creating image data of a B-mode image from the received signal from the detecting means, and the detecting means The ultrasonic diagnostic apparatus according to claim 1, wherein a low-pass filter is provided between the logarithmic compression unit or between the logarithmic compression unit and the display unit. The ultrasonic diagnostic apparatus according to claim 1, wherein a composition ratio input means for inputting the required composition ratio is provided on a console for inputting operator input information to the coefficient setting means. An electrical signal from the ultrasonic probe is received and converted into a reception circuit output signal, while the reception circuit output signal is converted into a filter output signal, and a B-mode image is converted from the reception circuit output signal or the filter output signal. In an ultrasonic diagnostic method for generating image data and displaying an image of a B-mode image,
Prior to diagnosis, a diagnosis pre-synthesis ratio setting step in which a synthesis ratio of the reception circuit output signal and the filter output signal at the time of diagnosis is set;
Prior to diagnosis, a diagnostic pre-combination ratio storage step in which a plurality of composite ratios set in the composite ratio setting step are stored;
A receiving circuit output signal receiving step in which the receiving circuit output signal is received at the time of diagnosis;
A filter output signal receiving step in which the filter output signal is received;
A required synthesis ratio setting step in which a required synthesis ratio is selected and set from the plurality of synthesis ratios;
A weighting step in which the reception circuit output signal and the filter output signal are respectively weighted at the required synthesis ratio selected in the required synthesis ratio selection step;
Each output signal weighted in the weighting step is combined and converted into a combined output signal;
And an image display step in which image data is acquired based on the combined output signal and an image is displayed. The composition ratio is set according to at least one required coefficient among a coefficient of a position unit in the depth direction of a two-dimensional tomographic image, a coefficient of a position unit in the scanning line direction, and a coefficient of a time unit. The ultrasonic diagnostic method according to claim 5. 6. The ultrasonic diagnostic method according to claim 5, wherein the selection of the required synthesis ratio in the required synthesis ratio setting step is automatically performed according to parameters such as a heart rate and a size of an examination site. An electrical signal from the ultrasonic probe is received and converted into a reception circuit output signal, while the reception circuit output signal is converted into a filter output signal, and a B-mode image is converted from the reception circuit output signal or the filter output signal. In an ultrasonic diagnostic method for generating image data and displaying an image of a B-mode image,
A required coefficient input step for inputting a required synthesis ratio of the receiving circuit output signal and the filter output signal at the time of diagnosis;
A required coefficient setting step in which the required composite ratio is set;
A receiving circuit output signal receiving step in which the receiving circuit output signal is received at the time of diagnosis;
A filter output signal receiving step in which the filter output signal is received;
A weighting step in which the receiving circuit output signal and the filter output signal are respectively weighted at the required synthesis ratio set in the required coefficient setting step;
Each output signal weighted in the weighting step is combined and converted into a combined output signal;
And an image display step in which image data is acquired based on the combined output signal and an image is displayed. The required composition ratio is set according to at least one required coefficient among a coefficient in a position unit in the depth direction of a two-dimensional tomogram, a coefficient in a position unit in the scanning line direction, and a coefficient in a time unit. The ultrasonic diagnostic method according to claim 8.

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