JP4693465B2 - Three-dimensional ultrasonic diagnostic apparatus and volume data display area setting method - Google Patents

Description

  The present invention relates to a three-dimensional ultrasonic diagnostic apparatus that displays a three-dimensional (3D) image in real time, and more particularly to a three-dimensional ultrasonic diagnostic apparatus used to determine a range of three-dimensional image data to be displayed. The present invention also relates to a volume data display area setting method executed in such a three-dimensional ultrasonic diagnostic apparatus.

  Currently, a real-time three-dimensional display function is put into practical use in an ultrasonic diagnostic apparatus (see, for example, Patent Document 1). Stack data collection for the three-dimensional reconstruction is roughly classified into one using a one-dimensional array probe and one using a two-dimensional array probe. The scanning method using a one-dimensional array probe includes a freehand scanning method and a mechanical method. There is a scan method.

  In the freehand scan method, there are a method of manually performing a turn (oscillation) scan, a parallel scan, or a rotational scan at a constant speed, and a method of mounting a position sensor such as a magnetic method on a probe and scanning in an arbitrary direction. .

  On the other hand, the mechanical scan system includes a probe and a probe driving motor in an enclosure, and performs a scan of the body surface probe (swing) and a rotational scan of the body cavity probe at a mechanically constant speed.

  The two-dimensional array probe method electronically scans and collects three-dimensional data using a vibrator arranged on a two-dimensional surface.

  FIG. 12 shows the state of the target area reconstructed from the stack data obtained by such a three-dimensional scan and displayed in three dimensions, taking the fetal head as an example. Here, the one-dimensional array probe is swung and scanned in the Z direction shown in the figure, CS101 shows a tomographic image, and CS102 shows a cross section in a direction orthogonal to CS101. FIGS. 13A and 13B show the cross sections CS101 and CS102 shown in FIG. 12, respectively.

When creating a three-dimensional image in real-time three-dimensional display, as shown in FIG. 13A, a region of interest (ROI) is set around the target region of imaging in advance on the ultrasonic image, and only the volume is stored in the region of interest. Display as data. As a result, the volume data creation amount can be reduced and the real-time property can be improved, and the obstacle OB101 such as the tissue in front of the target site and noise due to multiple reflections of ultrasonic waves can be excluded from the imaging range. it can. At this time, as shown in FIG. 13B, the ROI 101 has the same size on each tomographic image, and the shape of the volume data is automatically determined.
Japanese Patent Laid-Open No. 6-169921

  However, when imaging the target site and creating volume data, the tissue in front of the target site and obstacles such as noise due to multiple reflections of ultrasonic waves may obscure the target site and hinder observation. .

  In such a case, the ROI is set so as not to include such an obstacle. However, depending on the shape of the obstacle, there is a case where the ROI cannot be completely removed only by setting the ROI on the ultrasonic image. .

  For example, in the cross section CS101 shown in FIG. 13A, even if the ROI 101 is set so that obstacles such as noise due to multiple reflections are not included, as seen from the cross section CS102 shown in FIG. The volume data display area determined by the ROI 101 includes an obstacle OB101, and even if it is desired to observe the face of the fetus, the obstacle OB101 hinders observation.

  It is practically impossible to manually set the ROI for each image during image acquisition. Although it is possible to manually set the ROI for each image after collecting the images, the number of images is generally large, which is very troublesome and is not a practical method. The present invention has been made in view of the above-described circumstances, and easily determines a volume data display area that does not include obstacles such as tissue that interferes with observation and noise due to multiple reflections of ultrasonic waves. It is an object of the present invention to provide a three-dimensional ultrasonic diagnostic apparatus and a volume data display area setting method capable of performing the above.

3D ultrasound apparatus according to the present invention, in order to solve the above problems, as described in claim 1, and a three-dimensional scanning means for performing three-dimensional scanning of the ultrasound, the three-dimensional scanning and 2-dimensional ultrasound image generating means for generating a 2-dimensional image data based on the scanned information from the unit, 3-dimensional ultrasound image generating means for generating a three-dimensional image data based on the scanned information from the three-dimensional scanning means Image display means for displaying a two-dimensional image based on the two- dimensional image data, a three-dimensional image based on the three- dimensional image data, and each of the first direction and the second direction orthogonal to the three-dimensional image data and region of interest setting means for setting a plurality of regions of interest in the brightness gradient calculating means for calculating a luminance gradient image pixel value of each ROI of the set plurality of interest areas, each ROI the calculated No shine Boundary point determining means for determining an observation object boundary points other than the observation object based on the gradient, a display range determining means for determining the display range of the three-dimensional image based on the position of the determined boundary points , Are provided.

  According to the three-dimensional ultrasonic diagnostic apparatus and the volume data display area setting method according to the present invention, a volume data display area that does not include obstacles such as tissue that interferes with observation and noise due to multiple reflections of ultrasonic waves. Can be easily determined.

  Embodiments of an ultrasonic diagnostic apparatus according to the present invention will be described with reference to the accompanying drawings. FIG. 1 is a block diagram showing an overall schematic configuration of an ultrasonic diagnostic apparatus 1 according to the present embodiment.

  An ultrasonic diagnostic apparatus 1 shown in FIG. 1 includes an ultrasonic probe 2 that transmits / receives ultrasonic waves to / from a subject and an ultrasonic probe 2 that transmits / receives ultrasonic waves in a predetermined scanning direction. In the transmission / reception unit 3 that transmits and receives electrical signals, the image data generation unit 4 that generates two-dimensional ultrasonic image data based on the received ultrasonic signal obtained from a predetermined scanning direction, and the image data generation unit 4 And an image storage unit 5 that stores the generated ultrasonic image data.

  The ultrasonic diagnostic apparatus 1 includes an image data processing unit 8 that performs various processes on the ultrasonic image data generated by the image data generation unit 4, a collection condition of ultrasonic image data, an image data processing condition, Furthermore, an input unit 6 for inputting various command signals and the like, and a data storage unit 7 for storing various data excluding image data are provided.

  The ultrasonic diagnostic apparatus 1 also displays a volume projection unit 11 that reconstructs three-dimensional data from the ultrasonic image data generated by the image data generation unit, and displays the two-dimensional ultrasonic image data and the three-dimensional ultrasonic image. And an overlay drawing unit 9 for drawing an ROI on the display unit 12 and an image / overlay combining unit 10 for displaying the drawn ROI in a superimposed manner on a two-dimensional image.

  Although not shown, the ultrasonic probe 2 includes a vibrator that transmits and receives ultrasonic waves, a motor that is a scanning mechanism that mechanically scans the vibrator, and the current position of the vibrator, that is, the direction of the ultrasonic beam. And a position sensor for detecting. The ultrasonic probe 2 is an ultrasonic probe for taking in three-dimensional data, for example, used in contact with the body surface of a living body, and electronic scanning is used in combination with mechanical scanning. That is, an array transducer is provided as a transducer, and this array transducer performs electronic scanning in a predetermined direction by electronic scanning, and further performs mechanical scanning in a direction perpendicular thereto, thereby ultrasonic waves in a three-dimensional space. Enables transmission and reception of In the case of an ultrasonic probe for taking in three-dimensional data that is used in contact with the body surface of a living body, a turning (swinging) scan is performed as a mechanical scan.

  Position information from a position sensor included in the ultrasonic probe 2 is sent to a position detection unit (not shown) of the ultrasonic diagnostic apparatus 1 main body, and the position detection unit detects the position and inclination of the ultrasonic probe 1 to detect probe position data. Is generated.

  The transmission / reception unit 3 performs phasing addition on a transmission unit that generates a drive signal for generating transmission ultrasonic waves from the ultrasonic probe 2 and a reception signal of a plurality of channels obtained from the piezoelectric vibrator of the ultrasonic probe 2. On the other hand, the image data generation unit 4 receives a reception signal from the transmission / reception unit 3 and performs signal processing for generating two-dimensional ultrasonic image data on the reception signal subjected to phasing addition. . The image data storage unit 5 stores the two-dimensional ultrasonic image data generated and collected by the image data generation unit 4.

  The input unit 6 is a means for an operator to input various information for operating the ultrasonic diagnostic apparatus 1, and includes an input device such as a keyboard, a trackball, and a mouse and a display panel on the input panel. Patient information, diagnostic site, image data collection mode, image data processing method, image data display method, and various command signals are input. Also, information for moving the position of the ROI, changing the size, etc. is given via the input unit 6.

  The data storage unit 7 is a storage unit that stores various types of data other than image data such as information input via the input unit 6. The various types of data include at least ROI position information and volume display range information, which will be described later. It is.

  Next, the configuration of the image data processing unit 8 which is a main unit of the present embodiment will be described with reference to the block diagram shown in FIG. The image data processing unit 8 includes a luminance gradient calculation unit 81, a boundary point determination unit 82, and a display range determination unit 83, as shown in FIG.

  The luminance gradient calculation unit 81 reads the two-dimensional ultrasonic image data from the image data storage unit 5 and the position information of the ROI from the data storage unit 7, respectively, and the pixels inside the ROI set on the two-dimensional ultrasonic image The luminance gradient is obtained from the value.

  The boundary point determination unit 82 determines an observation object and a boundary point other than the observation object from the luminance gradient value obtained by the luminance gradient calculation unit 81, and the display range determination unit 83 further determines the boundary point determination unit 82. The display range of the three-dimensional ultrasonic image is determined based on the position of the boundary point. The data obtained by the boundary point determination unit 82 and the display range determination unit 83 is sequentially sent to the data storage unit 7 and stored in the data storage unit 7.

  The overlay drawing unit 9 draws the ROI based on the ROI position information input via the input unit 6. The ROI drawn by the overlay drawing unit 9 is superimposed on the two-dimensional ultrasonic image by the image / overlay synthesis unit 10.

  The volume projection unit 11 uses the plurality of 2D ultrasound image data received from the image data storage unit 5 and the volume display range information received from the data storage unit 7 to store the 2D ultrasound image data within the volume display range. Reconstruct 3D image data.

  The image display unit 12 includes a CRT or LCD, displays a two-dimensional ultrasonic image and a two-dimensional ultrasonic image on which the ROI is superimposed, and displays the three-dimensional image data reconstructed by the volume projection unit 11 on a two-dimensional screen. Projected on top.

  The ultrasonic diagnostic apparatus 1 includes a system control unit (not shown). The system control unit includes a CPU and a storage circuit, and comprehensively controls the above units of the ultrasonic diagnostic apparatus 1 and the entire system. .

  The input unit 6 and the data storage unit 7 in the present embodiment constitute an area setting unit according to the present invention, and the overlay drawing unit 9, the image / overlay synthesis unit 10, the volume projection unit 11, and the image in the present embodiment. The display unit 12 constitutes an image display unit according to the present invention.

  The ultrasonic diagnostic apparatus 1 according to the present embodiment is configured as described above, and the processing procedure will be described below taking a part including the head of the fetus E as an example. Note that the control of each unit and the data flow are all based on instructions from the system control unit, and description thereof is omitted. FIG. 3 is a flowchart showing a setting procedure of the boundary point search ROI.

  The transducer in the ultrasonic probe 2 transmits / receives ultrasonic waves to / from the subject while being driven by a motor to perform swinging motion (turning scanning). Then, the ultrasonic data received by the ultrasonic probe 2 is sent to the image data generation unit 4 via the transmission / reception unit 3, and a two-dimensional ultrasonic image is generated in the image data generation unit 4 (step S1). The image data is immediately stored in the image data storage unit 5.

  The two-dimensional ultrasonic image is further sent from the image data storage unit 5 to the image display unit 12 via the image / overlay synthesis unit 10, and a two-dimensional ultrasonic image is displayed (step S2). At this point, the ROI has not been synthesized yet.

  Next, as shown in FIG. 4, the three-dimensional maximum display range M is displayed so as to overlap the image (step S3). The three-dimensional maximum display range M is an ROI for designating on the two-dimensional image P a portion that the operator wants to display as a three-dimensional image. The three-dimensional maximum display range M is a rectangle, and the position information is stored in the data storage unit 7. When the position information is read from the data storage unit 7, it is drawn by the overlay drawing unit 9, and the drawn image data is sent to the image / overlay combining unit 10 and superimposed on the two-dimensional ultrasonic image P, and the image display unit 12. Both are displayed in a superimposed manner. The three-dimensional maximum display range M can be moved up, down, left, and right on the screen of the display unit 12 by moving a trackball or the like. All ROIs including the three-dimensional maximum display range M are superimposed and displayed on the two-dimensional ultrasonic image P in this way.

  Subsequently, the boundary point search ROIS is superimposed and displayed on the two-dimensional ultrasonic image P within the three-dimensional maximum display range M (step S4). The boundary point search ROIS is a small rectangle of 5 pixels on the left and right and 10 to 20 pixels on the top and bottom, and its position information is stored in the data storage unit 7. The boundary point search ROIS can be moved vertically and horizontally within the three-dimensional maximum display range M by moving the trackball or the like. When setting the boundary point search ROIS, the operator stops the oscillation of the transducer of the ultrasonic probe 2 when the approximate center of the head of the fetus E is imaged. Then, while viewing the screen, the boundary point search ROIS is moved so that the boundary point search ROIS is set to a position including the boundary between the fetus E portion and the background amniotic fluid A portion. When the boundary point search ROIS is arranged at a desired position, the operator instructs the completion of the setting of the boundary point search ROIS by clicking the mouse or the like.

  Next, the procedure for setting the volume display range will be described with reference to the flowchart shown in FIG. The captured two-dimensional ultrasonic image P is read from the image data storage unit 5 and sent to the luminance gradient calculation unit 81 in the image data processing unit 8 (step S11). At the same time, the position information of the boundary point search ROIS is read from the data storage unit 7 and sent to the luminance gradient calculation unit 81.

  The luminance gradient calculation unit 81 calculates a luminance gradient (pixel value gradient) from the pixel values inside the boundary point search ROIS (step S12). This calculation method will be described below. As shown in FIG. 6A, the boundary point search ROIS has a size of vertical M pixels and horizontal N pixels, and each pixel has a pixel value of Pjk.

First, as shown in FIG. 6B, the average A of pixel values is calculated in the horizontal direction of this boundary point search ROIS (A _j = (P _j1 + P _j2 +... + P _jN ) / N j = 1, 2,..., N). Then, from this average A, as shown in FIG. 6C, the gradient G of the pixel values is calculated in the vertical direction (G _j = (A _j−1 −A _{j + 1} ) / 2 where j = 2, 3, ..., M-1). The gradient G thus obtained becomes luminance gradient data.

  The luminance gradient data calculated in this way is sent to the boundary point determination unit 82, where a vertical position that gives the maximum value of the luminance gradient is obtained as shown in FIG. This position is set as a boundary point position T (step S13). In the two-dimensional ultrasound image, the fetus E portion has a higher luminance (pixel value) than the amniotic fluid A portion, so the position where the luminance gradient is maximum, that is, the change in luminance is maximum, is the boundary between the fetal E head and the amniotic fluid A portion. The point position T can be obtained.

  The position T of the boundary point thus obtained is stored in the data storage unit 7 and sent to the display range determining unit 83. In the display range determination unit 83, as shown in FIG. 7, in the three-dimensional maximum display range M, the range below the position above the position by the predetermined number of pixels from the position T of the obtained boundary point is displayed in this image. And the position information is stored in the data storage unit (step S14). Setting the volume display range V above the position T of the boundary point is a safety measure for preventing a part of the subject from being lost from the three-dimensional image.

  As shown in FIG. 8, the boundary point search ROI is set so that the obtained boundary point position T becomes the center of the boundary point search ROIS for the image captured next to the first captured image. It is automatically set (step S15). At this time, the position in the left-right direction of the boundary point search ROIS is not changed. Then, the two-dimensional ultrasonic image data is read from the image data storage unit 5 (step S16), the luminance gradient data is obtained in the luminance gradient calculation unit 81 by the same method as described above (step S17), and the boundary point determination unit 82 The position T of the boundary point is obtained (step S19), and the volume display range V of the image is determined by the display range determination unit 83 (step S20). By repeating this operation, the volume display range V is determined for images picked up one after another (step S21: Yes).

  When the two-dimensional ultrasonic image P to be imaged reaches the side of the head of the fetus E (the one with the ear), the head is not imaged thereafter. When this happens, it is no longer necessary to determine the position of the boundary point. In this state, since there is almost no luminance gradient, when the maximum value of the luminance gradient is smaller than a predetermined value (step S18: No), the position of the boundary point is stopped and the volume display range is not provided. The position of the boundary point search ROIS is not changed. When the vibrator swings in the opposite direction and an image of the same position is captured, the boundary point search ROIS is set to the same position, and the determination of the position of the boundary point is resumed.

  In this way, the volume display range V can be determined for each of the two-dimensional ultrasonic images that are sequentially captured. When the volume display range V can be determined for the two-dimensional ultrasound image P (corresponding to the one-way swing range) constituting one volume, the two-dimensional ultrasound image P is read from the image data storage unit 5. Further, the position information of the corresponding volume display range V is read from the data storage unit 7 and transmitted to the volume projection unit 11 to perform projection, and a three-dimensional image is displayed on the image display unit 12. Note that it is desirable that the screen is divided into left and right, and the captured two-dimensional image and three-dimensional image are displayed side by side.

  By setting the volume display range V in this way, as shown in FIG. 9, it is possible to exclude obstacles OB that could not be avoided by conventional ROI settings such as a three-dimensional maximum display range. . In addition, since the volume data area in the image is limited, it is possible to reduce the amount of data to be handled, thereby increasing the frame rate or improving the image quality.

  In the embodiment described above, only one boundary point search ROIS is set. However, two or more boundary point search ROISs may be set. For example, when two boundary point search ROISs are set, as shown in FIG. 10, outside the two obtained boundary points S1 and S2, line segments are set at the same level of the boundary points. A line segment connecting two boundary points may be set between the boundary points, and a line segment indicated by the volume display range V may be set on the upper side by a predetermined number of pixels. As a result, the volume display range V is further limited, and obstacle avoidance is more reliable.

  The embodiments described above are for illustrative purposes and do not limit the scope of the invention. Accordingly, those skilled in the art can employ embodiments in which each or all of these elements are replaced by equivalents thereof, and these embodiments are also included in the scope of the present invention.

  For example, in the present embodiment, the description has been given by taking the mechanical scan type as the ultrasonic probe as an example, but the ultrasonic probe is not limited to the mechanical scan type, and may be a free hand scan type. Alternatively, a two-dimensional array probe may be employed.

  In particular, when a two-dimensional array probe is employed, as shown in FIG. 11, a plurality of boundary point search ROISs can be set in each of the X-axis direction and the Z-axis direction. The point search ROIS can be arranged in a plane.

1 is a schematic block diagram showing the overall configuration of an ultrasonic diagnostic apparatus according to an embodiment of the present invention. FIG. 2 is a schematic block diagram illustrating a configuration of an image data processing unit according to the present embodiment. The flowchart which shows the setting procedure of ROI for boundary point search. The figure which shows ROI for a three-dimensional maximum display range and a boundary point search. The flowchart which shows the setting procedure of a volume display range. The figure explaining the calculation method of the brightness | luminance gradient inside the ROI for boundary point search. Explanatory drawing which shows the relationship between the position of the boundary point initially set, and the volume display range. Explanatory drawing which shows the position setting of the 2nd and subsequent boundary point. The figure explaining the positional relationship of a volume display range and an obstruction. Explanatory drawing which shows the relationship between the position of a boundary point, and a volume display range in case the number of boundary point search ROIs is two. The figure which shows the example which has arrange | positioned many boundary point search ROI surface. Conventional volume data display example. (A) is a figure which shows the cross section CS101 in FIG. 12, (b) is a figure which shows the CS102.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 3D ultrasonic diagnostic apparatus 2 Ultrasonic probe 3 Transmission / reception part 4 2D image generation part 5 Image storage part 6 Input part 7 Data storage part 8 Image data processing part 81 Luminance gradient calculation part 82 Boundary point determination part 83 Display range determination Unit 9 overlay drawing unit 10 image / overlay combining unit 11 volume projection unit 12 image display unit A amniotic fluid E subject M three-dimensional maximum display range OB obstacle P two-dimensional image S boundary point search ROI
T Boundary point position V Maximum volume display range

Claims (2)

Three-dimensional scanning means for performing ultrasonic three-dimensional scanning;
And 2-dimensional ultrasound image generating means for generating a 2-dimensional image data based on the scanned information from the three-dimensional scanning means,
And a three-dimensional ultrasound image generating means for generating a three-dimensional image data based on the scanned information from the three-dimensional scanning means,
Image display means for displaying a two-dimensional image based on the two- dimensional image data and a three-dimensional image based on the three- dimensional image data ;
Region-of-interest setting means for setting a plurality of regions of interest in each of the first direction and the second direction orthogonal to each other in the three-dimensional image data ;
A brightness gradient calculating means for calculating a luminance gradient image pixel value of each ROI of the set plurality of interest areas,
Boundary point determining means for determining the boundary points other than the observation object and the observation object based on the luminance gradient of each ROI the calculated,
A display range determining means for determining the display range of the three-dimensional image based on the position of the determined boundary points,
A three-dimensional ultrasonic diagnostic imaging apparatus comprising: Each region of interest of the set plurality of regions of interest is a rectangle having a plurality of pixel values in the first direction and a plurality of pixel values in the second direction,
The luminance gradient calculating unit calculates an average value of a plurality of pixel values in the second direction in each region of interest, and calculates the luminance from the plurality of average values in the first direction in each region of interest. The three-dimensional ultrasonic diagnostic imaging apparatus according to claim 1, wherein a gradient is obtained.

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