JP2006167267A - Ultrasonograph - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily compare between a real-time ultrasonogram and a reference image. <P>SOLUTION: An ultrasonograph is equipped with an ultrasonogram construction means 3 which reconstructs an ultrasonogram based on reflected echo signals measured by an ultrasound probe 1 transmitting and receiving ultrasound to and from a subject 100, an image position arithmetic means 7 which calculates a cross-sectional position of the ultrasonogram based on detected information on the position and the posture of the ultrasound probe 1, a recording medium 15 in which three-dimensional image data of the subject imaged in advance is recorded, and a reference image construction means 16 which clips the reference image corresponding to the cross-sectional position of the ultrasonogram out of the three-dimensional image data, and is characterized with a means 12 for managing conditions to display images for management conditions for displaying images displayed on a screen of a image display means 9 in accordance with instructions entered from an entry means 10 and outputs the conditions for displaying to the ultrasonogram construction means and the reference image construction means. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an ultrasonic diagnostic apparatus, and more particularly to a technique suitable for making a diagnosis by comparing two images of the same part that are imaged with time.

  Since the ultrasonic diagnostic apparatus can observe an ultrasonic image of an arbitrary cross section in real time, a diagnostic image of the same part (part of interest, for example, a tumor) of the same subject captured in advance before treatment or the like as a reference image, By comparing with a real-time ultrasonic image after treatment or during treatment, effective use as a diagnosis of treatment effect or as a guide at the time of treatment is achieved. Here, diagnostic images such as ultrasound images, X-ray CT images, and MR images can be used as reference images, and slices corresponding to real-time ultrasound images are obtained from the three-dimensional image data (volume data) of these diagnostic images. It is generated by cutting out the two-dimensional image data of the position.

  For example, in Patent Document 1, the position and orientation of an ultrasonic probe are detected, the spatial coordinate position of an ultrasonic tomographic image is determined, the corresponding CT image is reconstructed from three-dimensional volume data, and a reference image is obtained. Is displayed on the monitor.

JP-A-10-151131

  However, since the technique described in Patent Document 1 does not consider combining the display condition of the ultrasonic image drawn in real time with the display condition of the reference image, the following problem is caused. is there.

  For example, even if the display magnification of the real-time ultrasonic image is changed, the display magnification of the reference image is not changed. Therefore, the observer must compare and observe two images having different display magnifications. For this reason, there are problems that visibility in contrast observation is poor, inconvenience, and usability is poor.

  Similarly, in the real-time ultrasonic image, the field of view can be moved up and down in the depth direction, or the field of view can be freely changed by zooming. However, no consideration is given to changing the field of view of the reference image following these changes.

  Further, in general, an ultrasonic image is drawn with an image shape in which a sector shape or a central portion of a sector shape is removed depending on the type of the probe. However, in general, X-ray CT images and MR images are drawn as circular images called round-cut images, so that there is a sense of incongruity and poor visibility.

  An object of the present invention is to enable easy comparison of a real-time ultrasonic image and a reference image.

  In order to solve the above problems, the present invention captures in advance an ultrasonic image reconstructed based on a reflected echo signal received by an ultrasonic probe that transmits and receives ultrasonic waves to and from a subject. In an ultrasonic diagnostic apparatus that displays a reference image obtained by cutting out an image of a cross-sectional position corresponding to the ultrasonic image from the three-dimensional image data of the subject so that the reference image can be compared with the reference image, the reference image is the ultrasonic image The image is drawn according to the display conditions of the image.

  In other words, the reference image is reconstructed in accordance with at least one display condition of display magnification, up / down movement, up / down / left / right inversion, display depth, zoom, and image shape of the ultrasonic image. In these cases, any one of an ultrasonic image, an X-ray CT image, and an MR image can be applied as the reference image.

  A specific ultrasonic diagnostic apparatus of the present invention is an ultrasonic image constructing means for reconstructing an ultrasonic image based on a reflected echo signal measured by an ultrasonic probe that transmits and receives ultrasonic waves to and from a subject. And an image position calculation means for calculating the cross-sectional position of the ultrasonic image based on the detection information of the position and orientation of the ultrasonic probe, and a record in which the three-dimensional image data of the subject imaged in advance is recorded A medium, a reference image construction unit that cuts out a reference image corresponding to a cross-sectional position of the ultrasonic image calculated by the image position calculation unit from the three-dimensional image data, an image display unit, and an input unit, Manages display conditions of images to be displayed on the screen of the image display means according to instructions input from the input means, and also configures the ultrasonic image construction means and the reference image construction Characterized by comprising providing an image display condition managing means for outputting a display condition and stage.

  Further, display image control means for switching display modes between the reference image and the ultrasonic image to be displayed on the screen of the image display means according to an instruction input from the input means can be provided. In this case, the display mode can include a form in which one of the reference image and the ultrasonic image is switched and displayed and a form in which the reference image and the ultrasonic image are displayed side by side.

  Further, when reconstructing the reference image corresponding to the real-time ultrasound image, the reference image composing means interrupts the reconstructing of the reference image when the magnitude of the probe movement is equal to or larger than the set value. Can do. That is, in the operation of searching for a region of interest, the movement of the probe becomes large. In such a case, it is not necessary to display the reference image, so that useless processing can be omitted.

  According to the present invention, it is possible to easily compare a real-time ultrasonic image and a reference image.

  Hereinafter, the present invention will be described based on embodiments.

  FIG. 1 shows a block diagram of an embodiment of an ultrasonic diagnostic apparatus to which the present invention is applied. In the figure, the probe 1 is formed by incorporating a plurality of ultrasonic transducers. The probe 1 converts an ultrasonic signal output from the ultrasonic transmission / reception unit 2 into an ultrasonic wave and transmits the ultrasonic signal to a diagnostic part of the subject 100, and reflects an ultrasonic wave generated from the diagnostic part of the subject 100. It is converted to an echo signal and output to the ultrasonic transmission / reception unit 2. The ultrasonic transmission / reception unit 2 performs reception processing such as amplification, detection, and phasing addition on the reflected echo signal output from the probe 1 and outputs it to the ultrasonic image construction unit 3. The ultrasonic image construction unit 3 reconstructs an ultrasonic image (B-mode image) of the diagnostic region based on the input reflected echo signal and stores it in the memory of the cine memory unit 4. The cine memory unit 4 stores an ultrasonic image in a frame number of 2D image data. It comes to record with.

  The magnetic position sensor 5 detects the position and tilt angle (attitude) of the probe 1 with reference to the three-dimensional coordinate system of the subject 100 and outputs the detection information 6 to the image position calculation unit 7. It has become. The image position calculation unit 7 calculates the cross-sectional position of the ultrasonic image captured based on the position and orientation of the probe 1 and calculates the frame number from the cine memory unit 4. The frame number of the ultrasonic image input by the notification 14 is displayed. Are stored in association with each other.

  On the other hand, the ultrasonic image once stored in the cine memory unit 4 is transferred to the image display unit 9 via the display image control unit 8 and displayed on the screen in real time. The operation panel 10 includes a keyboard, a trackball, and the like. From the operation panel 10, designation of display conditions for the ultrasound image, a command for displaying the reference image, a command for display mode such as a method for displaying the ultrasound image displayed on the screen of the image display unit 9 and the reference image, and the like are input. It is supposed to be.

  For example, when a display condition such as a display magnification of the ultrasonic image is designated, a display condition instruction 11 is input from the operation panel 10 to the image display condition management unit 12. Here, as display conditions, in addition to display magnification, for example, vertical movement and zooming of the field of view of an ultrasonic image captured in real time by the probe 1 can be designated. Further, since the image shape is a sector shape or a shape obtained by cutting out the main part of the sector shape depending on the type of the probe 1, the type of the probe 1 is input as image shape information.

  The image display condition management unit 12 stores the display condition instruction 11 input from the operation panel 10 and outputs the display condition instruction 11 to the ultrasonic image forming unit 3 and the cine memory unit 4 as necessary. Yes. Thereby, the ultrasonic image construction unit 3 is configured to reconstruct an ultrasonic image having a display condition suitable for the display condition instruction 11. That is, based on the reflected echo signal input from the ultrasonic transmission / reception unit 2, the ultrasonic image subjected to the display magnification, vertical movement, and zoom processing of the ultrasonic image is reconstructed and stored in the cine memory unit 4. It has become. The ultrasonic image stored in the cine memory unit 4 is displayed on the image display unit 9 via the display image control unit 8. Further, as will be described later, the image display condition management unit 12 outputs a display condition instruction 11 to the reference image construction unit 16 so as to read a reference image suitable for the instruction.

  The display mode instruction 13 for the ultrasonic image and the reference image input from the operation panel 10 is input to the display image control unit 8. Here, the display mode of the image should be specified by selecting a display mode that switches between one of the reference image and the ultrasonic image, a mode that displays them side by side, and a display mode that is displayed on the menu screen, etc. Can be done. The display image control unit 8 displays the reference image and the ultrasonic image on the image display unit 9 in the designated display mode.

  Next, a part related to generation of a reference image according to the characteristic part of the present embodiment will be described. Volume data for the same subject 100 captured by the volume data acquisition processing unit 15 by an image diagnostic apparatus such as the ultrasonic diagnostic apparatus of the present embodiment, or another ultrasonic diagnostic apparatus, X-ray CT apparatus, or MRI apparatus. Is stored. The volume data is given coordinate information based on the spatial coordinate system of the image diagnostic device that has been imaged. 1 are lines used when volume data is acquired by the ultrasonic diagnostic apparatus according to the present embodiment, and detailed procedures will be described later. Further, as shown in the present embodiment, the volume data acquisition processing unit 15 may be provided inside the ultrasonic diagnostic apparatus, but may be provided in a recording medium such as a CD or a server on a network, or connected by a network. Alternatively, it may be obtained directly from an X-ray CT apparatus or an MRI apparatus.

  The reference image construction unit 16 takes in the cross-sectional position information 18 of the real-time ultrasonic image from the image position calculation unit 7 via the image position information acquisition unit 17 and converts the volume data of the volume data acquisition processing unit 15 into the cross-section position information 18. A reference image at a corresponding cross-sectional position is cut out and reconstructed. The image position information acquisition unit 17 receives the frame number of the real-time ultrasonic image notified from the cine memory unit 4. The cross-sectional position information 18 of the real-time ultrasonic image corresponding to is acquired from the image position calculation unit 7. The reference image reconstructed by the reference image construction unit 16 can be displayed on the image display unit 9 via the display image control unit 8.

  In particular, the reference image construction unit 16 cuts out the reference image in accordance with the display magnification of the real-time ultrasonic image in accordance with the display condition instruction 11 input from the image display condition management unit 12. For example, the ratio between the pixel size of the reference image and the pixel size of the real-time ultrasonic image is set in advance, and the reference image display magnification is set based on the ratio and the display magnification instructed from the image display condition management unit 12. Try to cut out. Further, the shape of the real-time ultrasonic image is determined based on the type information of the probe 1, and based on this, the shape of the reference image is cut out into a fan shape or a shape obtained by cutting out the main part of the fan shape. Further, in the case of vertical movement and zooming, the display start depth and display position are determined together with the display magnification and shape of the real-time image, and the reference image display position, display magnification and shape are made to coincide and cut out.

  Next, a procedure in the case of performing a comparative observation by displaying a reference image of the same part on the image display unit 9 while capturing a real-time ultrasonic image using the present embodiment will be described.

(Pre-observation processing)
First, FIG. 2 shows a volume data acquisition processing procedure that must be acquired in advance before actual contrast observation. As shown in the figure, among the volume data stored in the volume data acquisition processing unit 15, the volume data to be referred to is designated (S201). The designation method is performed by instructing a storage destination address or name using a menu or the like displayed on the image display unit 9.

  Next, on the designated volume data, a position that coincides with the reference point position of the probe 1 is designated by the X, Y, and Z coordinates of the orthogonal coordinates (S202). At this time, information on the probe 1 to be used may also be given, and the reference point position may be set in consideration of the maximum display width and the like that vary depending on the shape of the probe 1.

  Next, the designated reference point position is set on the ultrasonic diagnostic apparatus side. That is, the probe 1 is placed on the same part as the designated reference point on the subject 100, and setting execution is input through the operation panel 10 or the like (S203). Thereby, the positional relationship between the ultrasonic image and the reference image can be associated. This is the preparation process until the actual comparison observation is performed.

(Image position information acquisition process)
Here, with reference to FIG. 3, processing for calculating the cross-sectional position information 18 in the image position calculation unit 7 and processing for acquiring the cross-sectional position information 18 in the image position information acquisition unit 17 will be described. The image position calculation unit 7 calculates the cross-sectional position information 18 of the real-time ultrasonic image in real time. The image position information acquisition unit 17 performs processing for acquiring the cross-sectional position information 18 for the reference image in real time and processing for acquiring the cross-sectional position information 18 for the reference image during freezing.

  First, the image position calculation unit 7 determines whether or not it is frozen (S301). This determination is based on the frame number notified from the cine memory unit 4. Is changed to real time when the frame number is changed. When the value does not change, it can be determined that it is frozen. However, the determination of freeze is not limited to this method, and although not shown, a freeze command input to the operation panel 10 is output to the image position calculation unit 7 and determined based on this. be able to.

  If it is determined as real time, the detection information 6 of the position and orientation of the probe 1 is taken from the magnetic position sensor 5, the coordinate information of the cross-sectional position of the real-time ultrasonic image is obtained by calculation, and stored as the cross-sectional position information 18. (S302). Next, the frame number of the real-time ultrasonic image notified from the cine memory unit 4 is displayed. Is acquired (S303). Then, the sectional position information 18 and the frame number. Are stored in the memory in association with each other (S304).

  As a process common to both real time and freeze, the image position information acquisition unit 17 extracts the frame number of the currently displayed ultrasonic image notified from the cine memory unit 4 in order to cut out the reference image. (S305), and then the frame No. Is obtained from the image position calculation unit 7 (S306).

  Thus, the cross-sectional position information 18 corresponding to the ultrasonic image displayed on the image display unit 9 at the time of real time or freeze is acquired, and based on this, the reference image construction unit 16 cuts out the reference image from the volume data. The image is displayed on the image display unit 9 via the display image control unit 8.

(Contrast observation)
With reference to FIG. 4, the processing procedure when actually performing the contrast observation will be described. While looking at the image on the image display unit 9, the probe 1 is moved to the region of interest to be observed. When the probe 1 is moved, the position and orientation of the probe 1 are acquired one by one from the magnetic position sensor 5, and the cross-sectional position of the real-time ultrasonic image is determined by the image position calculation unit 7 based on the acquired detection information 6. Coordinates are calculated. The coordinates of the calculated cross-sectional position are the frame numbers notified from the cine memory unit 4. (S401).

  Next, when a reference image display activation command is output from the image display condition management unit 12, the reference image configuration unit 16 acquires ultrasonic image display conditions such as display magnification, vertical movement amount, and zoom information. (S402). Further, the cross-sectional position information 18 of the real-time ultrasonic image is acquired from the image position information acquisition unit 17 and an image of the cross-sectional position on the volume data corresponding to the cross-sectional position is extracted. Further, the extracted reference image is reconstructed according to the display condition of the ultrasonic image (S403). That is, based on the display conditions instructed from the image display condition management unit 12, the extracted reference image is enlarged or reduced, or the display position is limited based on the vertical movement or zoom function of the image. Further, in the case of a sector image, the sector image is cut out according to the shape of the probe 1, and in the case of a convex image, the upper side of the sector shape is cut out in an arc shape or the like in accordance with the display of the ultrasonic image. Thereby, the reference image having the same part and the same cross section as the real-time ultrasonic image can be drawn on the image display unit 9 under the same display conditions.

  Further, the reference image created in this way is drawn on the image display unit 9 together with the real-time ultrasonic image or independently according to the display mode instruction 13 input to the display image control unit 8 (S404). As described above, this display form is displayed according to a display mode selected on the reference image and the ultrasonic image by switching one of them, displaying them side by side, or displaying them side by side. For example, when displaying a reference image, a three-dimensional image of volume data may be displayed on the same screen. Needless to say, the reference image can be displayed as a moving image in accordance with the movement of the ultrasonic image.

  In this way, as shown in FIG. 5, the display conditions of the ultrasonic image and the reference image displayed on the image display unit 9 are displayed together. That is, the example of the display image shown in FIG. 5 is an example using an X-ray CT image or an MR image as a reference image. As shown in FIG. 5A, a real-time or frozen ultrasound image 32 is displayed on the left half of the display screen 31, and a reference image 33 is displayed on the right half. As illustrated, the reference image 33 is displayed with the same display magnification as the ultrasonic image 32 and with the same image shape. Therefore, the contrast observation of both images can be easily performed.

  On the other hand, when a region of interest 34 is set in the ultrasound image 32 from the operation panel 10 and a zoom-up command is input for this region, an ultrasound image 35 in which a portion of the region of interest 34 is enlarged as shown in FIG. Is displayed. On the other hand, when the reference image 33 is displayed with the display magnification shown in FIG. 6A, the display image 33 is displayed with the display magnification as shown in FIG. In this regard, according to the present embodiment, the reference image 36 is enlarged and displayed in accordance with the zoomed-up ultrasonic image 35 as shown in FIG.

  5A or 5C, a three-dimensional image 37 of the region of the region of interest 34 can be displayed in a partial region of the display screen 31. Further, as shown in FIG. 5A, when the resolution of the reference image 33 is good, a region of interest 38 is set in the reference image 33, and the ultrasound image 35 is enlarged and displayed based on the region of interest 38. It may be. The regions of interest 34 and 38 can be operated to enlarge, reduce, and move up, down, left and right by inputting from the operation panel 10. Further, in the display state of FIG. 5C, the operator can operate the operation panel 10 to enlarge, reduce, and move the region of interest vertically and horizontally.

  As described above, according to the present embodiment, the observer displays the reference image of the same rendering position and the same image display condition corresponding to the ultrasonic image displayed in real time or the ultrasonic image displayed as freeze display on the screen. Therefore, the contrast observation of both images can be easily performed. As a result, since both images can be compared and observed without a sense of incongruity, the use as a guideline at the time of treatment and the usability when used for determining the treatment effect of a patient are improved, and the diagnosis effect can be improved. In addition, it can be used for education of diagnosis using ultrasonic images.

(Reference image generation timing)
In the above embodiment, the processing when there is a difference between the generation times of the ultrasonic image and the reference image has not been described. However, in general, the process of extracting and reconstructing a reference image corresponding to an ultrasound image from volume data takes more time than the process of reconstructing a real-time ultrasound image.

  An example of the timing of processing for cutting out and reconstructing a reference image from volume data and processing for reconstructing a real-time ultrasound image will be described with reference to FIG. In FIG. 6, real-time ultrasonic images 41 are periodically picked up and frame No. 1, 2,... Are added and sequentially stored in the cine memory unit 4. In addition, the image position calculation unit 7 receives the frame number. At each update timing 42, the detection information 6 of the position and orientation of the probe 1 is fetched from the magnetic position sensor 5, and the cross-sectional position information 18 of the real-time ultrasonic image is calculated. Record in association with.

  On the other hand, the reference image construction unit 16 generates one reference image for several frames of the ultrasonic image. For example, frame No. 1 is started at the update timing of the frame No. 3 at the update timing, A reference image 43 corresponding to one ultrasonic image is displayed. Also, frame No. 3 is started at the update timing of the frame No. 6 at the update timing. A reference image 44 corresponding to the ultrasonic image 3 is displayed.

  Also, frame No. When the freeze-on command 45 is input from the operation panel 10 at the timing when the ultrasonic image of No. 6 is displayed, the frame number at the time of freeze-on is displayed. The frame No. Is obtained from the image position calculation unit 7. Then, a reference image 46 corresponding to the ultrasonic image at freeze-on is generated and displayed. Further, when the cine reproduction of the ultrasonic image stored in the cine memory unit 4 is performed, the frame number notified from the cine memory unit 4 is the same as in the freeze. Is obtained, and a reference image is generated and displayed. As the display condition at the time of cine reproduction, the display condition immediately before freezing, which is the display condition of the cine memory image, is acquired from the ultrasonic image construction unit 3 to generate a reference image.

  Furthermore, it is possible to slightly delay the screen display of the ultrasonic image in consideration of the frame rate of the ultrasonic image and the generation time of the reference image. Depending on the delay time, processing for obtaining the cross-sectional position information 18 and processing for matching the display conditions of the image may be added. Also, the position or time difference between the two images may be displayed on the screen as a figure or text.

  Also, in real time, the magnitude of the movement of the probe 1 is monitored. When the movement of the probe 1 is large, the generation of the reference image is interrupted, and when the movement is small or stopped, Generation can be resumed. According to this, in the case of an operation in which the probe 1 is simply moved to search for a region of interest, drawing of the reference image is unnecessary, and therefore unnecessary processing can be eliminated.

(Volume data collection of ultrasound images)
In the above description, the X-ray CT image or the MR image has been described as an example of the reference image volume data. However, as described above, the reference image volume data is collected by the ultrasonic diagnostic apparatus of the embodiment of FIG. can do. In this case, the probe 1 is applied to the body surface of the diagnostic region of the subject 100 and moved in one direction, and an ultrasonic image of the peripheral region including the diagnostic region is acquired. Then, the volume data acquisition processing unit 15 converts the real-time ultrasonic image from the cine memory unit 4 to frame No. Together with the frame number from the image position calculation unit 7. Is acquired, and three-dimensional volume data of the ultrasonic image is collected.

(Display mode example)
Next, a display mode on the display screen of the image display unit 9 by switching the display image control unit 8 will be described with reference to FIG. For example, as shown in FIGS. 7A to 7E, the display mode is arbitrarily selected by the function assigned to each key of the operation panel 10 or the function of the icon 51 shown in FIG. Can be switched. FIG. 4A shows a typical contrast display example in which the ultrasonic image 52 and the reference image 53 are displayed on two screens. FIG. 2B is a two-screen display example of the reference image 54 under the same display conditions as the ultrasonic image 52. FIGS. 7C and 7D are one-screen display examples of the ultrasonic image 52 and the reference image 53, respectively. FIG. 5E is a display example of the display screen of the ultrasonic image 52, the reference image 53, and the 3D image 55 related to the reference image. Here, a cut plate 56 indicating the cross-sectional position of the reference image 53 can also be displayed in the 3D image of FIG.

  FIG. 8 shows an example of an actual display mode displayed on the display screen of the image display unit 9. FIG. 6A shows a display screen at the time of setup when generating and displaying the reference image of the present embodiment using the volume data of the X-ray CT image. Based on the figure, a reference point of the probe 1 is set, and the probe 1 is applied to the position, and the correspondence between the coordinate system of the volume data and the coordinate system of the ultrasonic diagnostic apparatus is set. FIG. 7B shows a display mode corresponding to FIG. 7B, in which the left ultrasonic image and the right reference image are displayed under the same display conditions.

  Further, the display mode described with reference to FIGS. 7 and 8 is not limited to the display of the real-time ultrasonic image, and can be applied at the time of freezing or cine reproduction.

  Further, based on the three-dimensional volume data of the ultrasonic image and the three-dimensional volume data such as the X-ray CT image stored in the volume data acquisition processing unit 15, the two images of the ultrasonic image and the reference image are each three-dimensionally converted. It is also possible to display. Also in this three-dimensional display, the 3D configuration position, the 3D display direction, and the display conditions of the two images can be matched.

1 is a block diagram of an ultrasonic diagnostic apparatus according to an embodiment of the present invention. It is a flowchart which shows the procedure of the pre-process of contrast observation. It is a flowchart which shows the process sequence of image position calculation and position information acquisition. It is a flowchart which shows the procedure of contrast observation processing. It is a figure which shows an example of the image display of this invention. It is a figure explaining the update timing of a reference image. It is a figure explaining switching of the display mode of this invention. It is a figure explaining the other example of the image display of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Probe 2 Ultrasonic wave transmission / reception part 3 Ultrasonic image structure part 4 Cine memory part 5 Magnetic position sensor 7 Image position calculating part 8 Display image control part 9 Image display part 10 Operation panel 12 Image display condition management part 15 Volume data acquisition process Unit 16 Reference image configuration unit 17 Image position information acquisition unit

Claims (7)

From the ultrasound image reconstructed based on the reflected echo signal received by the ultrasound probe that transmits and receives ultrasound to and from the subject, and the three-dimensional image data of the subject imaged in advance, the ultrasound In an ultrasonic diagnostic apparatus that displays a reference image obtained by cutting out an image of a cross-sectional position corresponding to an image on a display screen in a comparable manner,
The ultrasonic diagnostic apparatus, wherein the reference image is drawn according to display conditions of the ultrasonic image.   2. The ultrasonic diagnostic apparatus according to claim 1, wherein the display condition is at least one of display magnification, vertical movement, vertical and horizontal reversal, display depth, zoom, and image shape.   2. The ultrasonic diagnostic apparatus according to claim 1, wherein the reference image is any one of an ultrasonic image, an X-ray CT image, and an MR image. Ultrasound image constructing means for reconstructing an ultrasound image based on a reflected echo signal measured by an ultrasound probe that transmits and receives ultrasound to and from the subject, and the position and orientation of the ultrasound probe Calculated by the image position calculating means for calculating the cross-sectional position of the ultrasonic image based on the detected information, the recording medium on which the three-dimensional image data of the subject imaged in advance is recorded, and the image position calculating means A reference image constituting unit that cuts out a reference image corresponding to a cross-sectional position of the ultrasonic image from the three-dimensional image data, an image display unit, and an input unit;
Image display condition management for managing display conditions of images to be displayed on the screen of the image display means in accordance with instructions input from the input means and outputting display conditions to the ultrasonic image construction means and the reference image construction means An ultrasonic diagnostic apparatus characterized by comprising means.   5. The display image control means for switching a display mode between the reference image and the ultrasonic image to be displayed on the screen of the image display means according to an instruction input from the input means. The ultrasonic diagnostic apparatus as described.   The ultrasonic diagnostic apparatus according to claim 5, wherein the display mode includes a form in which one of the reference image and the ultrasonic image is switched and displayed side by side.   When reconstructing a reference image corresponding to a real-time ultrasound image, the reference image composing means interrupts reconstructing the reference image when the magnitude of the movement of the probe is a set value or more. The ultrasonic diagnostic apparatus according to claim 5.

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