JP5213083B2 - Ultrasonic imaging device - Google Patents

Description

  The present invention relates to an ultrasonic imaging apparatus that acquires tomographic image information of a subject to which a contrast agent is administered.

  In recent years, contrast medium inspection is also performed in ultrasonic imaging apparatuses. In these contrast medium examinations, the contrast medium infiltrated into the bloodstream or tissue part generates high-intensity ultrasonic waves or reflects ultrasonic waves containing harmonic components against the ultrasonic waves irradiated in the subject. To do. These contrast agents are destroyed or generate harmonics by the sound pressure of the irradiated ultrasonic waves.

  For example, in contrast agent A (Levovist), ultrasonic waves with high sound pressure are irradiated to destroy the shell of the contrast agent, and the ultrasonic waves generated at the time of destruction are observed. In contrast agent B (Sonazoid), ultrasonic waves with low sound pressure are irradiated, and the harmonic components of the transmitted ultrasonic waves reflected at this time are observed. In this contrast agent B, irradiating an ultrasonic wave with a high sound pressure leads to destruction of the contrast agent, which is not preferable for imaging.

When performing imaging using a contrast agent, an operator adjusts the sound pressure of the transmitted ultrasonic wave in consideration of the type of the contrast agent used, the imaging purpose, and the like. The sound pressure is adjusted by the MI (Mechanical) displayed on the screen.
This is done with reference to the (Index) value. This MI value is based on a draft report on ensuring the safety of ultrasonic devices for the living body established by WFUMB (World Union of Ultrasonics and Medical Physiology), and cavitations generated in the living body due to the negative sound pressure of ultrasonic waves ( This is an index for preventing the mechanical action of cavitation).

The MI value is an index defined by the negative sound pressure Pr3 and the frequency f in the tissue of the subject, and is a parameter that reflects the sound pressure of ultrasonic waves in water. The MI value displayed on the ultrasonic imaging apparatus displays the maximum MI value in the subject, and an index indicating the maximum sound pressure of the ultrasound in the subject when imaging the contrast medium of the subject Used as For example, when the contrast agent A is used, a scan parameter (scan) having a high MI value is used.
parameter) value and destroy the contrast agent. When the contrast agent B is used, a scan parameter value having a low MI value is set, and imaging using a harmonic component of reflected ultrasound is performed (see, for example, Non-Patent Document 1).

Edited by Japan Electronic Machinery Manufacturers Association, “Revised Medical Ultrasound Handbook”, Corona, January 20, 1997, p. 53-54, p. 212-213

  However, according to the above background art, it is not possible to set the sound pressure in consideration of the sound pressure distribution of the ultrasonic wave in the subject. That is, the ultrasonic wave irradiated from the probe part propagates through the subject while being attenuated. At this time, the sound pressure at each part in the subject is influenced by the ultrasonic directivity of the probe part, the attenuation in the subject, the focal position, and the like, and varies from place to place.

  In particular, in the sound pressure distribution in the depth direction where ultrasonic waves are transmitted and received, the sound pressure decreases at a position deviating from the focal depth position. For example, when imaging is performed by destroying the contrast agent, the sound pressure may not be reached depending on the position of the contrast agent. In this case, the contrast agent can be destroyed by increasing the MI value. However, use of an unnecessarily high MI value is not preferable from the viewpoint of safety, which is the purpose of establishing the MI value. Therefore, it is preferable that the MI value is set to an appropriate value in consideration of the sound pressure distribution determined by the scan parameter values such as the imaging position and the focal depth position of the contrast agent.

  The present invention has been made in order to solve the above-described problems of the background art, and is capable of determining the sound pressure of the ultrasonic wave to be irradiated in consideration of the sound pressure distribution of the ultrasonic wave in the subject. An object is to provide an apparatus.

  In order to solve the above-described problems and achieve the object, the ultrasonic imaging apparatus according to the first aspect of the invention irradiates an imaging region of a subject with ultrasonic waves, and obtains tomographic image information for rendering the imaging region. An image acquisition unit to be acquired, a sound pressure distribution calculation unit for calculating sound pressure distribution information of the ultrasonic wave in the imaging region, and a display unit for displaying the sound pressure distribution information together with the tomographic image information.

  In the invention according to the first aspect, the sound pressure distribution information is displayed together with the tomographic image information on the display unit.

  The ultrasonic imaging apparatus according to the second aspect of the invention is the ultrasonic imaging apparatus according to the first aspect, wherein the image acquisition unit changes the maximum drive voltage of the piezoelectric element that performs the irradiation of the ultrasonic waves. The driving voltage varying means is provided.

  In the second aspect of the invention, the sound pressure distribution is changed by the drive voltage varying means.

  The ultrasonic imaging apparatus according to the invention of the third aspect is the ultrasonic imaging apparatus according to the first or second aspect, wherein the sound pressure distribution information is MI value distribution information or Pr three-value distribution of the imaging region. It is characterized by being information.

  In the invention of the third aspect, the MI value distribution or the Pr3 value distribution used in the safety standard is used as an index of the sound pressure distribution.

  An ultrasonic imaging apparatus according to a fourth aspect of the invention is the ultrasonic imaging apparatus according to the third aspect, wherein the MI value distribution information or the Pr3 value distribution information is in the depth direction in which the irradiation is performed. It is the information of sound pressure distribution of.

  In the invention of the fourth aspect, the MI value distribution information or the Pr3 value distribution information includes only the main sound pressure distribution.

  An ultrasonic imaging apparatus according to a fifth aspect of the invention is the ultrasonic imaging apparatus according to the fourth aspect, in which the display unit displays the depth direction of the tomographic image information; The MI value distribution information or the Pr3 value distribution information is made to coincide with the direction in which the depth direction display is performed.

  In the fifth aspect of the invention, the MI value distribution information or the Pr3 value distribution information is easily compared with the tomographic image information.

  Further, an ultrasonic imaging apparatus according to a sixth aspect of the invention is the ultrasonic imaging apparatus according to the fifth aspect, wherein the display unit has the MI value of the MI value distribution information or the Pr3 of the Pr3 value distribution information. The magnitude of the value is displayed as a value of a coordinate axis in a direction orthogonal to the depth direction.

  In the sixth aspect of the invention, the sound pressure distribution information is displayed as a MI value distribution function or a Pr3 value distribution function.

  The ultrasonic imaging apparatus according to the seventh aspect of the invention is the ultrasonic imaging apparatus according to the fifth aspect, wherein the display unit is configured such that the MI value of the MI value distribution information or the Pr3 value of the Pr3 value distribution information. The magnitude of the value is displayed on a monochrome gradation scale having a monochrome gradation corresponding to the magnitude or a hue scale having a hue corresponding to the magnitude.

  In the invention of the seventh aspect, the sound pressure distribution information is expressed as a monochrome gradation scale or a hue scale.

  Further, an ultrasonic imaging apparatus according to an eighth aspect of the invention is the ultrasonic imaging apparatus according to the fifth aspect, wherein the display unit is configured such that the MI value of the MI value distribution information or the Pr3 value of the Pr3 value distribution information. The magnitude of the value is displayed as background image information superimposed on the tomographic image information, having a hue corresponding to the magnitude and having a uniform hue area in a direction orthogonal to the depth direction. It is characterized by.

  In the invention of the eighth aspect, the sound pressure distribution is expressed by the background color of the tomographic image information.

  The ultrasonic imaging apparatus according to the ninth aspect of the invention is the ultrasonic imaging apparatus according to any one of the first to eighth aspects, wherein the ultrasonic imaging apparatus is a contrast agent in the subject. Sound pressure setting means for setting sound pressure information indicating a lower limit value of the ultrasonic sound pressure that breaks the sound pressure, and the sound pressure distribution calculating unit has a sound pressure equal to or higher than the sound pressure of the sound pressure destruction information The contrast agent destruction region in the depth direction of the imaging region is obtained, and the display unit superimposes uniform background image information having a hue different from that of the tomographic image information on the contrast agent destruction region of the tomographic image information. It is characterized by displaying.

  In the ninth aspect of the invention, the region where the contrast agent is destroyed is clearly indicated as a region of a different hue in the displayed tomographic image information.

  An ultrasonic imaging apparatus according to a tenth aspect of the invention includes an image acquisition unit that irradiates an imaging region of a subject with ultrasonic waves, acquires tomographic image information that depicts the imaging region, and the tomographic image information. A display unit for displaying, a region of interest setting means for setting a region of interest in the imaging region of the displayed tomographic image information, and a destructive sound pressure indicating a lower limit value of the ultrasonic sound pressure for destructing the contrast agent in the subject Destructive sound pressure setting means for setting information, and sound pressure distribution optimizing means for optimizing the sound pressure distribution of the ultrasonic wave in the region of interest based on the destructive sound pressure information.

  In the tenth aspect of the invention, the sound pressure distribution of the ultrasonic wave in the region of interest is optimized by the sound pressure distribution optimizing means.

  An ultrasonic imaging apparatus according to an eleventh aspect of the invention is the ultrasonic imaging apparatus according to the tenth aspect, wherein the destructive sound pressure information is MI value information or Pr3 value information. .

  In the eleventh aspect of the invention, the MI value or the Pr3 value used in the safety standard is used as the breaking sound pressure information.

  An ultrasonic imaging apparatus according to a twelfth aspect of the invention is the ultrasonic imaging apparatus according to the tenth or eleventh aspect, wherein the sound pressure distribution information indicates a sound pressure distribution in the depth direction at which the irradiation is performed. It is characterized by including.

  In the twelfth aspect of the invention, the sound pressure distribution information includes only the main sound pressure distribution.

  An ultrasonic imaging apparatus according to a thirteenth aspect of the invention is the ultrasonic imaging apparatus according to any one of the tenth to twelfth aspects, in which the sound pressure distribution optimization unit stores the tomographic image information. A sound pressure distribution calculating unit that calculates sound pressure distribution information of the ultrasonic wave in the region of interest using a scan parameter value at the time of acquisition is provided.

  In the thirteenth aspect of the invention, sound pressure distribution information is obtained from the scan parameter value.

  The ultrasonic imaging apparatus according to the fourteenth aspect of the invention is the ultrasonic imaging apparatus according to the thirteenth aspect, wherein the scan parameter value includes aperture width information, apodization information, depth of focus information, and power value information. It contains a value.

  An ultrasonic imaging apparatus according to a fifteenth aspect of the present invention is the ultrasonic imaging apparatus according to the thirteenth or fourteenth aspect, wherein the sound pressure distribution optimization unit changes the scan parameter value and An optimization calculation unit for obtaining sound pressure distribution information for each parameter value is provided.

  In the fifteenth aspect of the invention, the optimization calculation unit obtains various sound pressure distribution information by changing the scan parameter value.

  An ultrasonic imaging apparatus according to a sixteenth aspect of the invention is the ultrasonic imaging apparatus according to the fifteenth aspect, in which the optimization calculation unit converts the scan parameter value into the sound pressure of the sound pressure distribution information. The distribution is optimized to include a maximum sound pressure in the region of interest.

  In the sixteenth aspect of the invention, the region of interest has the highest sensitivity.

  The ultrasonic imaging apparatus according to the seventeenth aspect of the invention is the ultrasonic imaging apparatus according to the fifteenth or sixteenth aspect, in which the optimization calculation unit converts the scan parameter value into the sound pressure distribution information. The sound pressure distribution is optimized so as to be equal to or higher than the destructive sound pressure of the destructive sound pressure information.

  In the seventeenth aspect of the invention, the contrast agent is destroyed, and the ultrasonic waves generated at the time of destruction are imaged.

  An ultrasonic imaging apparatus according to an eighteenth aspect of the invention is the ultrasonic imaging apparatus according to the fifteenth or sixteenth aspect, in which the optimization calculation unit converts the scan parameter value into the sound pressure distribution information. The sound pressure distribution is optimized so as to be less than the destructive sound pressure of the destructive sound pressure information.

  In the eighteenth aspect of the invention, the contrast agent is repeatedly irradiated with ultrasonic waves, and the harmonics contained in the reflected waves are observed.

  The ultrasonic imaging apparatus according to the nineteenth aspect of the invention is the ultrasonic imaging apparatus according to any one of the fifteenth to eighteenth aspects, in which the optimization calculation unit sets the scan parameter value as the value. The sound pressure distribution information is optimized so as to minimize the variance of the sound pressure distribution.

  In the nineteenth aspect of the invention, the sound pressure distribution in the region of interest is made as uniform as possible.

  An ultrasonic imaging apparatus according to a twentieth aspect of the invention is the ultrasonic imaging apparatus according to any one of the fifteenth to nineteenth aspects, in which the sound pressure distribution optimization means sets the scan parameter value. A scan parameter value setting unit that is set in the image acquisition unit is provided.

  In the twentieth aspect of the invention, imaging is performed using the optimized scan parameter value.

  According to the present invention, since the scan parameter value is determined in consideration of the sound pressure distribution information of the region of interest, it is possible to reliably perform imaging of the contrast agent as intended by the operator, and thus high quality. A contrast agent image can be acquired.

FIG. 1 is a block diagram showing the overall configuration of the ultrasonic imaging apparatus. FIG. 2 is an external view showing the configuration of the input unit. FIG. 3 is a block diagram of the configuration of the control unit according to the first embodiment. FIG. 4 is an explanatory diagram showing the sound pressure distribution in the depth direction of the transmitted ultrasonic waves. FIG. 5 is an explanatory diagram showing an example of a hue correspondence table of the hue correspondence means. FIG. 6 is a block diagram illustrating a configuration of the image display control unit according to the first embodiment. FIG. 7 is an explanatory diagram of an example of tomographic image information and sound pressure distribution information displayed on the display unit (part 1). FIG. 8 is an explanatory diagram of an example of tomographic image information and sound pressure distribution information displayed on the display unit (part 2). FIG. 9 is a flowchart illustrating the operation of the ultrasonic imaging apparatus according to the first embodiment. FIG. 10 is an explanatory diagram illustrating an example of a display form in which the contrast agent destruction region is displayed so as to overlap the tomographic image information. FIG. 11 is a block diagram of a configuration of a control unit according to the second embodiment. FIG. 12 is a flowchart of the operation of the control unit according to the second embodiment (part 1). FIG. 13 is a flowchart of the operation of the control unit according to the second embodiment (part 2). FIG. 14 is an explanatory diagram illustrating an example of a region of interest set in a B-mode image. FIG. 15 is an explanatory diagram illustrating an example of sound pressure distribution information having the maximum sound pressure in the region of interest.

The best mode for carrying out an ultrasonic imaging apparatus according to the present invention will be described below with reference to the accompanying drawings. Note that the present invention is not limited thereby.
<Embodiment 1>

First, the overall configuration of the ultrasonic imaging apparatus 100 according to the first embodiment will be described. FIG. 1 is a block diagram showing the overall configuration of the ultrasonic imaging apparatus 100 according to the first embodiment. The ultrasonic imaging apparatus 100 includes a probe unit 101, an image acquisition unit 109, a cine memory unit (cine).
memory) section 104, image display control section 105, display section 106, input section 107, and control section 108. Image acquisition section 109 further includes transmission / reception section 102 and image processing section 103.

  The probe unit 101 repeatedly irradiates ultrasonic waves in a specific direction of an imaging cross section of the subject 1 for transmitting / receiving ultrasonic waves, and reflects ultrasonic signals reflected from the inside of the subject 1 in time series. Received as a typical sound ray. The probe unit 101 performs electronic scanning while sequentially switching the irradiation direction of the ultrasonic waves. Piezoelectric elements (not shown) are arranged in an array in the probe unit 101.

  The transmitting / receiving unit 102 is connected to the probe unit 101 by a coaxial cable (cable), and performs first-stage amplification of the electrical signal for driving the piezoelectric element of the probe unit 101 and the received ultrasonic signal. In the case of transmission of ultrasonic waves, the transmission / reception unit 102 delays the transmission signal to focus on the focal position. The transmission / reception unit 102 includes a drive voltage varying unit 12, and the drive voltage varying unit 12 changes the maximum voltage for driving the piezoelectric element in accordance with a control signal from the control unit 108. Therefore, the drive voltage varying unit 12 changes the maximum sound pressure of the ultrasonic wave irradiated to the subject. The control unit 108 determines this maximum voltage based on the value of the power level PL set from the input unit 107.

  The image processing unit 103 forms tomographic image information such as B-mode image information from the formation of an electrical signal that drives the transmission / reception unit 102 and the ultrasonic signal amplified by the transmission / reception unit 102. In particular, when a contrast medium is administered to the subject 1, a contrast mode process is performed in which the scan parameter value is optimized for imaging the contrast medium, and contrast mode image information is acquired.

  When receiving an ultrasonic wave, the image processing unit 103 performs a delay addition process, an A / D (analog / digital) conversion process, a filter process, and the like on the received ultrasonic signal, and converts the digital information into one piece. It is assumed that the piece of tomographic image information.

  The cine memory unit 104 is a cine memory for storing tomographic image information and the like generated by the contrast mode processing. In particular, the cine memory unit 104 stores the tomographic image information that changes with time together with the time information at which the tomographic image information is acquired with a frame that is one piece of tomographic image information as a minimum unit.

The image display control unit 105 performs display frame rate conversion of the tomographic image information generated by the image processing unit 103, color display control, and shape and position control of the display image of the tomographic image information. The image display control unit 105 also displays an ROI (Region) indicating a region of interest on a display image such as tomographic image information.
Of Interest) is also displayed.

  The display unit 106 visually displays the image information output from the image display control unit 105 using a cathode ray tube (CRT) or a liquid crystal display (LCD). The display unit 106 can also perform color display according to an instruction from the image display control unit 105.

  The control unit 108 controls the operation of each unit of the above-described ultrasonic imaging apparatus 100 based on the operation input signal given from the input unit 107 and the program (program) and data (data) stored in advance, and displays on the display unit 106. A B-mode image or the like that is tomographic image information is displayed.

  The input unit 107 includes a keyboard, a pointing device, and the like. The operator inputs an operation input signal for selecting an imaging mode, a scan parameter value when performing imaging, and the like, and transmits them to the control unit 108. It is done.

FIG. 2 is an explanatory diagram illustrating an example of the input unit 107. The input unit 107 includes a keyboard 70, a TGC (Time Gain Controller) 71, a new patient key (New).
It includes a patient designation unit 72 including a patient key), a track ball, etc., and a measurement input unit 73 and a contrast mode setting unit 74 that are also ROIs and other regions of interest setting means.

  The TGC 71 adjusts the gain in the depth direction of the displayed tomographic image information, the patient designating unit 72 includes a key selected when imaging a new subject, and the measurement input unit 73 includes a display unit A function for measuring the shape, position, size, and the like of the region of interest when setting the region of interest in 106 and the pixel value of the set region of interest is set. When imaging using a contrast medium is performed, destructive sound pressure information that destroys the contrast medium is input.

  The contrast mode setting means 74 includes a contrast agent destruction selection key 75 and a destruction sound pressure setting means 76, and the contrast agent destruction selection key 75 is turned on and off to select whether the contrast agent is to be destroyed or not discarded. A value designated by the volume of 76 is input to the control unit 108 as destructive sound pressure information.

  FIG. 3 is a block diagram illustrating a configuration of the control unit 108. The control unit 108 includes an image acquisition control unit 88 and a sound pressure distribution calculation unit 85.

  The image acquisition control unit 88 performs ultrasonic scanning based on scan parameter value information such as imaging mode designation information, drive voltage information, focus position information, and drive frequency information from the input unit 107 to acquire tomographic image information. . In particular, the image acquisition control unit 88 controls the maximum sound pressure of the ultrasonic pulse to be irradiated using the drive voltage varying unit 12 according to the designation from the input unit 107.

  The sound pressure distribution calculation unit 85 includes a sound pressure distribution information setting unit 87 and a hue correspondence unit 86.

  The sound pressure distribution information setting unit 87 determines the distribution of the sound pressure parameter values in the subject 1 based on the scan parameter value information from the image acquisition control unit 88 and the sound pressure distribution information set in advance from the input unit 107 or the like. Form. Here, MI, Pr3, etc. are used as the sound pressure parameters. MI is the negative sound pressure Pr3 (Mpa; megapascal) in the tissue part of the subject 1.

MI = Pr3 / f ^1/2
Have the relationship. Here, f (MHz; megahertz) is the center frequency of the ultrasonic wave. From this relationship, the value of MI is calculated using the value of Pr3.

  The negative sound pressure Pr3 in the tissue is obtained by using the negative sound pressure Pr in water and the constant k.

Pr3 = k × Pr
Expressed in relation to From this relationship, the value of Pr3 is calculated using the value of the negative sound pressure Pr in water.

  The negative sound pressure Pr in water is the peak value Pm of the sound pressure that changes sinusoidally in water.

Pr = Pm-Ps
Have the relationship. Here, Ps is a static pressure (usually 1 atm). From this relationship, the underwater negative sound pressure Ps is calculated using the underwater sound pressure Pm.

  The underwater sound pressure peak value Pm is obtained from the scan parameter value and the experimentally measured sound pressure distribution in water. The distribution of the sound pressure Pm in water under a predetermined scan parameter value is obtained experimentally in advance, for example, by movement of a hydrophone installed in the water. The distribution information of the sound pressure Pm is set in the sound pressure distribution information setting unit 87 as non-volatile information manually input from the input unit 107 or written in a ROM or the like.

  FIG. 4 is an explanatory diagram showing an example of the acquired sound pressure distribution function. The depth direction from the probe unit 101 into the subject 1 is taken as the horizontal axis (z axis), and the sound pressure Pm indicated by the irradiated ultrasonic wave is taken as the vertical axis. Here, the z axis forming the horizontal axis has the surface of the probe unit 101 in contact with the subject 1 as the origin. The sound pressure distribution in the depth direction shows the maximum sound pressure at a position near the focal depth FD, and thereafter gradually decreases the sound pressure.

The sound pressure distribution information Pm (Z) as shown in FIG. 4 is changed by changing the scan parameter value. The scan parameter value for changing the sound pressure distribution includes type information Ty including the resonance frequency of the probe unit 101, the depth of focus FD of the electronic focus performed in the scanning direction, and the number of piezoelectric elements that are simultaneously driven in the scanning direction. Aperture width AW, apodization information AP, and power level (Power) for setting the maximum drive voltage for driving the piezoelectric element
Level) PL exists. The sound pressure distribution information Pm (Z) is corrected by the values of these scan parameters. If this correction function is g,

Pm (Z) = g (Z, Ty, FD, AW, AP, PL,...)
It can appear. The sound pressure distribution information setting unit 87 calculates Pm (Z) using the correction function g at the same time as the scan parameter value is input, and further calculates the MI value using the above-described conversion formula. The MI value distribution function is obtained.

  The hue correspondence unit 86 includes a hue correspondence table that associates MI values with hues, and associates MI values with hues when displayed on the display unit 106. FIG. 5 is an example of the hue correspondence table 20. The hue correspondence table associates zero to maximum values of MI values with blue-violet to red of visible light. The hue is specified using a code such as an RGB expression, and is matched with the hue code instructed from the image display control unit 105 to the display unit 106.

  The hue correspondence unit 86 associates the MI value of the MI value distribution function obtained by the sound pressure distribution information setting unit 87 with the hue using the hue correspondence table 20 based on the instruction signal from the input unit 107, and the hue distribution function. Is output to the image display control unit 105 as sound pressure distribution information.

  FIG. 6 is a block diagram illustrating a configuration of the image display control unit 105. The image display control unit 105 includes a writing unit 31, an image memory 32, and a reading unit 33.

  The image memory 32 is a memory including information corresponding to image information displayed on the display screen of the display unit 106 on a one-to-one basis. The writing unit 31 writes the tomographic image information 41 and the sound pressure distribution information 42 from the image processing unit 103, the cine memory unit 104, and the control unit 108 at the address position of the image memory 32 designated by the control unit 108. Based on the signal designating the display position on the display screen from the control unit 108, the reading unit 33 outputs the pixel value information of the image memory 32 corresponding to the display position to the display.

  Here, the display operation of the image display control unit 105 will be described. The image display control unit 105 displays both the content of the sound pressure distribution information 42 as shown in FIG. 4 and the tomographic image information 41 such as B-mode image information on the display unit 106. Here, examples in which the tomographic image information 41 and the sound pressure distribution information 42 are displayed together by the image display control unit 105 are shown in FIGS. Note that the sound rays that constitute the tomographic image information 41 and that are arranged in the scanning direction have the same sound ray distribution information 42.

  7A shows an image displayed on the display unit 106 when the sound pressure distribution information 42 includes the MI value distribution function 62 in the depth direction (Z direction) as shown in FIG. It is. The tomographic image information 41 is displayed on the left side of the display unit 106, and the MI value distribution function 62 is displayed on the right side. The tomographic image information 41 located on the left side displays tomographic images from the shallow part to the deep part of the subject 1 from the top to the bottom of the display unit 106. In the MI value distribution function 62 located on the right side, the horizontal axis representing the depth is directed in the vertical direction, and the depth position is matched with the depth position of the tomographic image information 41 displayed on the left side. In the MI value distribution function 62, the axis representing the MI value is directed in the left-right direction, and the distribution of the MI value in the depth direction is represented as a line graph.

  FIG. 7B is a diagram showing an image displayed on the display unit 106 when the sound pressure distribution information 42 includes the monochrome gradation scale 63. The tomographic image information 41 is displayed on the left side of the display unit 106, and the monochrome gradation scale 63 is displayed on the right side. The tomographic image information 41 located on the left side displays tomographic images from the shallow part to the deep part of the subject 1 from the top to the bottom of the display unit 106. The black-and-white gradation scale 63 located on the right side is a gradation scale (scale) in which the brightness changes in the depth direction facing the vertical direction, similar to the tomographic image information 41. In the black-and-white gradation scale shown in FIG. 7B, the high MI value corresponds to the low luminance and the low MI value corresponds to the high luminance. However, the correspondence between the MI value and the luminance is reversed to increase the high MI value. Can correspond to high luminance, and low MI value can correspond to low luminance.

  FIG. 8A is a diagram showing an image displayed on the display unit 106 when the hue scale 64 is included as the sound pressure distribution information 42. The tomographic image information 41 is displayed on the left side of the display unit 106, and the hue scale 64 is displayed on the right side. The tomographic image information 41 located on the left side displays tomographic images from the shallow part to the deep part of the subject 1 from the top to the bottom of the display unit 106. The hue scale 64 located on the right side has a scale in which the hue changes in the depth direction facing the vertical direction, similar to the tomographic image information 41. The hue scale shown in FIG. 8A is based on the hue correspondence table shown in FIG. 5, and the high MI value has a hue close to red and the low MI value has a hue close to violet.

  FIG. 8B is a diagram schematically illustrating an image when the background image information 45 displayed on the tomographic image information 41 is displayed on the display unit 106 instead of the hue scale 64. In this case, the background image information 45 has the same width as the tomographic image information 41 in the left-right direction, and is displayed at the same position as the tomographic image information 41. Further, each hue constituting the background image information 45 has a low luminance. As a result, the tomographic image information 41 displayed in an overlapping manner becomes observable using the superimposed translucent hue scale as a background image. Note that a portion corresponding to a hue boundary of the hue scale 64 illustrated in FIG. 8A is indicated by a one-dot chain line in the background image information 45 illustrated in FIG.

  Next, the operation of the ultrasonic imaging apparatus 100 according to the first embodiment will be described with reference to FIG. First, the operator sets scan parameter values such as a depth of focus and a power level for generating transmission ultrasonic waves from the input unit 107 (step S701). Here, the sound pressure distribution information setting unit 87 of the control unit 108 generates the sound pressure distribution information 42 based on the scan parameter value.

  Thereafter, the operator designates display of the sound pressure distribution information 42 from the keyboard or the like of the input unit 107, and displays the sound pressure distribution information 42 (step S702). Then, the operator brings the probe unit 101 into close contact with the target imaging area of the subject 1 and performs imaging of this imaging area (step S703).

  Thereafter, the operator observes any of the display images on the display unit 106 shown in FIGS. 7 to 8 and determines whether or not the sound pressure distribution is appropriate (step S704). For example, the operator determines whether or not the destruction sound pressure is in a position corresponding to the path where the contrast medium flows in the imaging region, and whether or not the region that is the destruction sound pressure has a sufficient width or more than necessary. It is determined whether or not the area of the sound pressure for destruction is enlarged. If the sound pressure distribution is not appropriate (No at Step S704), the operator proceeds to Step S701, changes the scan parameter value such as the focal depth position or the power level, and performs imaging again. Changing the focal depth position changes the area position of the sound pressure in the depth direction, and changing the power level changes the area of the sound pressure area.

  When the sound pressure distribution is appropriate (Yes at Step S704), the operator administers a contrast agent to the subject 1 (Step S705), and performs imaging of the contrast agent in the imaging region of the subject 1 (Step S705). S706), the process is terminated. Note that the tomographic image information such as the contrast mode image information acquired here is obtained by appropriately destroying the contrast agent at the target position.

  As described above, in the first embodiment, the sound pressure distribution information 42 is displayed side by side or superimposed with the tomographic image information 41, so that the operator has the sound pressure in the imaging region before imaging. By grasping the region where the contrast sound pressure of the contrast agent is broken, and by re-setting the scan parameter value, the region where the contrast agent is destroyed is matched with the position where the contrast agent is depicted in the imaging region. It is possible to reliably destroy the contrast medium.

  In the first embodiment, the MI value distribution function is displayed as an example. Similarly, the distribution of the sound pressure parameter values related to the sound pressure such as the Pr3 value, the sound pressure Pm, or the negative sound pressure Pr is obtained. It can also be displayed.

  In the first embodiment, the case of destroying the contrast agent has been exemplified. However, the present invention can be used in the same manner when imaging is performed using a harmonic component reflected from the contrast agent. In this case, since imaging is performed in a low sound pressure area that does not destroy the contrast agent, the operator refers to the sound pressure distribution information 42 and grasps the low sound pressure area where the harmonic component is properly generated. This region is made to coincide with the region where the contrast agent is drawn.

  In the first embodiment, the sound pressure distribution information 42 is displayed together with the tomographic image information 41 on the display unit 106. However, the destructive sound pressure information indicating the minimum destructive sound pressure is further input, and the tomographic image information is displayed. The region where the contrast medium 41 is destroyed can be shown more clearly by color coding or the like.

  FIG. 10 is a diagram in which the same graphs of tomographic image information 41 and MI value distribution function 62 as shown in FIG. 7A are displayed side by side. In the graph of the MI value distribution function, a destruction MI value 91 which is destruction sound pressure information input from the input unit 107 is illustrated. The destruction MI value 91 is an index indicating the minimum destruction sound pressure indicated by the MI value. When the MI value is greater than or equal to the destruction MI value 91, the contrast agent is destroyed and high-intensity ultrasonic waves are emitted. On the other hand, when the MI value is less than the destruction MI value 91, the contrast agent is not destroyed and high-intensity ultrasonic waves are not generated.

Here, the sound pressure distribution calculation unit 85 uses the graph of the MI value distribution function 62 to obtain a contrast agent destruction region 93 that is a region having an MI value greater than or equal to the destruction MI value 91. The image display control unit 105 assumes that the depth region corresponding to the contrast agent destruction region 93 of the tomographic image information 41 is overlaid with, for example, destruction region image information 94 having a red uniform background image. The destruction area image information 94 is the same as the background image information 45 shown in FIG. 8B, and a red background area with low luminance is displayed superimposed on the tomographic image information 41. Thus, the operator can easily grasp the area where the contrast agent is destroyed as the red area in the tomographic image information 41 in which the black and white gradation expression is made.
<Embodiment 2>

  In the first embodiment, the sound pressure distribution information in the depth direction is displayed on the display unit 106, and the operator refers to the sound pressure distribution information to determine whether or not the set scan parameter value is appropriate. However, it is also possible to automatically optimize the scan parameter value by providing sound pressure distribution optimization means in the control unit. Therefore, in the second embodiment, a case where sound pressure distribution optimization means is provided and the sound pressure distribution information is set to an optimum distribution targeted by the operator is shown.

  Here, the ultrasonic imaging apparatus according to the second embodiment is exactly the same as the ultrasonic imaging apparatus 100 illustrated in FIG. 1 except for the control unit 108. Therefore, in the second embodiment, only the control unit 118 corresponding to the control unit 108 will be described, and description of other configurations will be omitted.

  The control unit 118 includes an image acquisition control unit 88 and a sound pressure distribution optimization unit 51. The image acquisition control unit 88 is exactly the same as the image acquisition control unit 88 of the ultrasonic imaging apparatus 100 shown in FIG.

  The sound pressure distribution optimization unit 51 includes an optimization calculation unit 52, a sound pressure distribution calculation unit 85, and a scan parameter value setting unit 54. The sound pressure distribution calculation unit 85 is exactly the same as the sound pressure distribution calculation unit 85 of the control unit 108 shown in FIG.

  The sound pressure distribution calculation unit 85 scan information value information from the optimization calculation unit 52, for example, type information Ty including the resonance frequency of the probe unit 101, the depth of focus FD of electronic focus performed in the scanning direction, scanning The sound pressure distribution information Pm (Z) in the depth direction Z is corrected based on the opening width AW indicating the number of piezoelectric elements that are simultaneously driven in the direction, the apodization information AP, the power level PL that drives the piezoelectric elements, and the like. Using,

Pm (Z) = g (Z, Ty, FD, AW, AP, PL,...)
Ask for.

  The optimization calculation unit 52 obtains the sound pressure distribution information Pm (Z) in the depth direction of the region of interest set from the input unit 107 using the sound pressure distribution calculation unit 85 while changing the scan parameter value. Here, the changed scan parameter values include the focal depth FD, the aperture width AW, the apodization information AP, the power level PL, and the like that affect the sound pressure distribution. For example, when FD = 5 cm, 10 cm, and 15 cm can be set as the value of the focal depth of transmitted ultrasound, the sound pressure distribution for all combinations of other scan parameter value information and these three scan parameter values Information Pm (Z) is obtained. When obtaining the sound pressure distribution information Pm (Z), the power level PL is fixed to a predetermined value. Since the power level PL changes the maximum driving voltage, only the magnitude of the sound pressure is changed without changing the sound pressure distribution shape in the depth direction. The power level PL is used as a parameter that is changed when the sound pressure is finally determined after the comparison with the breaking sound pressure.

  The optimization calculation unit 52 further selects optimal sound pressure distribution information suitable for imaging from the sound pressure distribution information Pm (Z). The selection of the sound pressure distribution information will be described in detail in the operation of the sound pressure distribution optimization unit 51 of the control unit 118 described later.

  The scan parameter value setting unit 54 transmits the scan parameter value of the optimum sound pressure distribution information to the image acquisition control unit 88, and the image acquisition control unit 88 determines each part of the image acquisition unit 109 based on the scan parameter value. Set up.

  Next, the operation of the control unit 118 according to the second embodiment will be described with reference to FIGS. 12 and 13 are flowcharts showing the operation of the control unit 118. First, the operator selects the destruction or non-destruction of the contrast agent administered to the subject 1 and sets the destruction sound pressure information from the contrast mode setting means 74 of the input unit 107 (step S801). The destructive sound pressure information is information on the lower limit value of the sound pressure at which the contrast agent is destroyed in the subject 1, and the ultrasonic wave exceeding this sound pressure destroys the contrast agent in the subject 1. In setting, it is possible to set using the MI value, Pr3 value, Pr value or Pm value of the sound pressure at which the contrast agent is destroyed.

  Thereafter, the operator sets a region of interest from the input unit 107 while referring to a B-mode image displayed on the display unit 106 (step S802). FIG. 14 is an explanatory diagram illustrating an example of the region of interest 15 set in the B-mode image 14. In the region of interest 15, the position in the depth direction is set from a to b so as to include the observation position of the contrast agent intended by the operator.

  Thereafter, returning to FIG. 12, the sound pressure distribution optimization unit 51 performs sound pressure distribution optimization processing (step S803). FIG. 13 is a flowchart showing the operation of the sound pressure distribution optimization process. The optimization calculation unit 52 of the sound pressure distribution optimization unit 51 changes the scan parameter value, and obtains sound pressure distribution information Pm (Z) for each scan parameter value (step S901). The sound pressure distribution information Pm (Z) has a shape as shown in FIG.

  Thereafter, the optimization calculation unit 52 obtains the maximum sound pressure and the depth direction position of the maximum sound pressure for each sound pressure distribution information Pm (Z), and the sound pressure distribution information in which the depth direction position is included in the region of interest 15. Pm (Z) is selected (step S902). 15A to 15D are explanatory diagrams showing some examples of the sound pressure distribution information Pm (Z) selected here.

  The sound pressure distribution information Pm (Z) shown in FIGS. 15A to 15D has the maximum sound pressure between the positions a and b in the depth direction that is the range of the region of interest 15. Also, the sound pressure distribution information Pm (Z) shown in FIGS. 15A to 15D is different in the depth of focus FD, the aperture width AW, the apodization AP, and the like, and all have different sound pressure distributions.

  Returning to FIG. 13, the optimization calculation unit 52 obtains a statistical variance of the sound pressure distribution information Pm (Z) included in the region of interest 15 and selects the sound pressure distribution information Pm (Z) having the smallest variance ( Step S903). For example, when selecting the sound pressure distribution information having the smallest variance from the sound pressure distribution information Pm (Z) shown in FIGS. 15A to 15D, in the sections a to b in the depth direction. The sound pressure distribution information Pm (Z) shown in FIG. 5B with the least fluctuation is selected.

  Thereafter, the optimization calculation unit 52 determines whether or not to destroy the contrast agent administered to the subject 1 based on the instruction information from the contrast agent destruction selection key 75 (step S904). When destroying the contrast agent (Yes at Step S904), the optimization calculation unit 52 uses the sound pressure distribution information Pm (Z) selected at Step S903 to minimize the sound pressure in the sections a and b. However, the power level PL is set so that the sound pressure is equal to or higher than the destructive sound pressure of the destructive sound pressure information set in step S801 (step S905). Here, for example, the optimization calculation unit 52 obtains the minimum value of the sound pressure included in the sound pressure distribution information Pm (Z) in the sections a and b, and the power level PL so as to match the minimum value with the destructive sound pressure. Set. In FIG. 15B, an example of this power level is shown as a PL breakdown value.

  If the contrast agent is not destroyed (No at Step S904), the optimization calculation unit 52 obtains the maximum value of the sound pressure of the selection (Z) at Step S903, and this maximum value is less than the destruction sound pressure. The power level PL is set as follows. In FIG. 15B, an example of this power level is shown as a PL non-destructive value.

  Thereafter, the scan parameter value setting unit 54 transmits the scan parameter value including the power level PL transmitted from the optimization calculation unit 52 to the image acquisition control unit 88, and ends the sound pressure distribution optimization process.

  Thereafter, returning to FIG. 12, the operator performs imaging of the contrast agent using the scan parameter value (step S804), and ends this processing.

  As described above, in the second embodiment, the sound pressure distribution optimization unit 51 reduces the sound pressure of the sound pressure distribution information set in advance in the region of interest 15 with a small variance and the sound pressure in the region of interest 15. Therefore, the target contrast agent can be definitely imaged in the region of interest 15.

  In the second embodiment, the optimization calculation unit 52 determines the sound pressure distribution information Pm (Z) by changing the values of all the scan parameters except the power level PL. For shortening, the sound pressure distribution information Pm (Z) can be obtained using only limited scan parameters.

  In the second embodiment, the optimization calculation unit 52 has only the optimum sound pressure distribution information Pm (Z). For example, the size of the region of interest 15 in the depth direction and the maximum drive There may be a case where the optimum sound pressure distribution information Pm (Z) does not exist due to the limit value of the power level PL based on the upper limit value of the voltage. In this case, for example, the optimization calculation unit 52 selects the sound pressure distribution information Pm (Z) having a variance value that is sequentially larger than the minimum value instead of the minimum value of the variance value, and performs steps S904 to S907 to obtain the optimum value. Sound pressure distribution information can be obtained.

  In the second embodiment, the sound pressure distribution optimization unit 51 uses the value of the sound pressure Pm, which is the peak value of the sound pressure that changes sinusoidally in water, as the sound pressure distribution information. The optimization can also be performed based on sound pressure distribution information using indices such as Pr, Pr3, and MI obtained from Pm in exactly the same manner.

1: Subject
12: Driving voltage variable means
14: B-mode image
15: Area of interest
20: Hue correspondence table
31: Writing section
32: Image memory
33: Reading unit
41: Tomographic image information
42: Sound pressure distribution information
45: Background image information
51: Sound pressure distribution optimization means
52: Optimization calculation unit
54: Scan parameter value setting section
62: MI value distribution function
63: Monochrome gradation scale
64: Hue scale
70: Keyboard
72: Patient designation part
73: Measurement input section
74: Destructive sound pressure setting means
75: Volume selection key
76: Destructive sound pressure setting means
85: Sound pressure distribution calculation section
86: Hue correspondence means
87: Sound pressure distribution information setting section
88: Image acquisition control unit
91: Destruction MI value
93: Contrast medium destruction region
94: Destruction area image information
100: Ultrasonic imaging apparatus
101: Probe part
102: Transmission / reception unit
103: Image processing unit
104: Cine memory unit
105: Image display control unit
106: Display unit
107: Input unit
108, 118: Control unit
109: Image acquisition unit

Claims (11)

An image acquisition unit that irradiates an imaging region of a subject with ultrasonic waves and acquires tomographic image information that depicts the imaging region;
A display unit for displaying the tomographic image information;
A region of interest setting means for setting a region of interest in the imaging region of the displayed tomographic image information;
Destructive sound pressure setting means for setting destructive sound pressure information indicating a lower limit value of ultrasonic sound pressure for destroying the contrast agent in the subject,
An ultrasonic imaging apparatus comprising: sound pressure distribution optimization means for optimizing sound pressure distribution information of the ultrasonic wave in the region of interest based on the destructive sound pressure information.   2. The ultrasonic imaging apparatus according to claim 1, wherein the destructive sound pressure information is MI value information or Pr3 value information.   The ultrasonic imaging apparatus according to claim 1, wherein the sound pressure distribution information includes a sound pressure distribution in a depth direction in which the irradiation is performed.   The sound pressure distribution optimizing means includes a sound pressure distribution calculating unit that calculates sound pressure distribution information of the ultrasonic wave in the region of interest using a scan parameter value when acquiring the tomographic image information. The ultrasonic imaging apparatus according to any one of claims 1 to 3.   The ultrasonic imaging apparatus according to claim 4, wherein the scan parameter value includes values of aperture width information, apodization information, depth of focus information, and power value information.   The ultrasonic wave according to claim 4 or 5, wherein the sound pressure distribution optimizing unit includes an optimization calculation unit that changes the scan parameter value to obtain sound pressure distribution information for each scan parameter value. Imaging device.   The ultrasound according to claim 6, wherein the optimization calculation unit optimizes the scan parameter value so that a sound pressure distribution of the sound pressure distribution information includes a maximum sound pressure in the region of interest. Imaging device.   The said optimization calculating part optimizes the said scan parameter value so that the sound pressure distribution of the said sound pressure distribution information becomes more than the destructive sound pressure of the said destructive sound pressure information. The ultrasonic imaging apparatus described in 1.   The said optimization calculating part optimizes the said scan parameter value so that the sound pressure distribution of the said sound pressure distribution information may become less than the destructive sound pressure of the said destructive sound pressure information. The ultrasonic imaging apparatus described in 1.   The said optimization calculating part optimizes the said scan parameter value so that the dispersion | distribution which the sound pressure distribution of the said sound pressure distribution information has may be minimized. The ultrasonic imaging apparatus described.   11. The ultrasonic imaging according to claim 6, wherein the sound pressure distribution optimization unit includes a scan parameter value setting unit that sets the scan parameter value in the image acquisition unit. apparatus.