Patent Publication Number: US-2007100238-A1

Title: System and method for forming 3-dimensional images using multiple sectional plane images

Description:
FIELD OF THE INVENTION  
      The present invention generally relates to image forming systems, and more particularly to a system and a method for forming a 3-dimensional image by using multiple sectional plane images of a target object.  
     BACKGROUND OF THE INVENTION  
      An ultrasound diagnostic system has become an important and popular diagnostic tool since it has a wide range of applications. Specifically, due to its non-invasive and non-destructive nature, the ultrasound diagnostic system has been extensively used in the medical profession. Modern high-performance ultrasound diagnostic systems and techniques are commonly used to produce two or three-dimensional diagnostic images of internal features of an object (e.g., human organs).  
      The ultrasound diagnostic system generally uses a wide bandwidth transducer to transmit and receive ultrasound signals. The ultrasound diagnostic system forms images of human internal tissues by electrically exciting an acoustic transducer element or an array of acoustic transducer elements to generate ultrasound signals that travel into the body. The ultrasound signals produce ultrasound echo signals since they are reflected from body tissues, which appear as discontinuities to the propagating ultrasound signals. Various ultrasound echo signals return to the transducer element and are converted into electrical signals, which are amplified and processed to produce ultrasound data for an image of the tissues. The ultrasound diagnostic system is very important in the medical field since it provides physicians with real-time and high-resolution images of human internal features without the need for invasive observation techniques such as surgery.  
      The conventional ultrasound diagnostic system acquires 3-dimensional ultrasound data from ultrasound echo signals and forms a 3-dimensional ultrasound image based on the acquired 3-dimensional ultrasound data. In such a case, the entire 3-dimensional ultrasound data are used to form one 3-dimensional ultrasound image, even if the desired portions are different from each other, according to the users&#39; or specific diagnostic purposes. Therefore, such ultrasound diagnostic system is highly inconvenient since the user is required to find a desirable portion in the 3-dimensional ultrasound image.  
      Also, since the conventional ultrasound diagnostic system uses the entire 3-dimensional ultrasound data to form the 3-dimensional ultrasound image, it takes a very long time to form the 3-dimensional ultrasound image.  
     SUMMARY OF THE INVENTION  
      The present invention provides a system and a method for setting a region of interest on multiple sectional plane images, extracting data included in the region of interest from 3-dimensional ultrasound image data and performing image rendering for the extracted data, thereby forming a desirable 3-dimensional ultrasound image,  
      According to one aspect of the present invention, there is provided a system for forming 3-dimensional images, including: an image data forming unit for forming 3-dimensional volume data based on image signals; an image forming unit for forming multiple sectional plane images sliced along a predetermined direction in a 3-dimensional image, the image forming unit being configured to form at least one 3-dimensional image with partial 3-dimensional volume data selected by using the multiple sectional plane images from the 3-dimensional volume data; and a displaying unit for displaying the multiple sectional plane images and the 3-dimensional image.  
      According to another aspect of the present invention, there is provided a method of forming 3-dimensional images, including the steps of: a) forming 3-dimensional volume data based on image signals; b) forming multiple sectional plane images sliced along a predetermined direction in a 3-dimensional image; c) selecting one of the multiple section plane images; d) forming a reference sectional plane image orthogonal to the selected sectional plane image; e) setting a predetermined region on the reference sectional plane image; f) extracting data included in the predetermined region from the 3-dimensional volume data; g) performing image rendering for the extracted data; and h) forming at least one 3-dimensional image. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The above and other objects and features of the present invention will become apparent from the following descriptions of preferred embodiments given in conjunction with the accompanying drawings, in which:  
       FIG. 1  is a block diagram showing an ultrasound diagnostic system constructed in accordance with the present invention;  
       FIG. 2  is a flowchart illustrating the operation of an image processor constructed in accordance with the present invention;  
       FIG. 3  is a schematic diagram showing examples of sectional plane images in 3-dimensional ultrasound image data;  
       FIG. 4  shows multiple sectional plane images and a reference sectional plane image in accordance with the present invention;  
       FIG. 5  shows an example of setting a 3-dimensional region on the reference sectional plane image in accordance with the present invention;  
       FIG. 6  shows an example of slicing a 3-dimensional region on the reference sectional plane image in accordance with the present invention;  
       FIG. 7  shows an example of displaying slab images in accordance with the present invention; and  
       FIG. 8  shows an example of displaying the extracted sectional plane images included in the 3-dimensional region selected on a reference sectional image in accordance with the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PRESENT INVENTION  
       FIG. 1  is a block diagram showing an ultrasound diagnostic system  100 , which is constructed in accordance with the present invention. The ultrasound diagnostic system  100  of the present invention includes a probe  110 , a beam former  120 , an image signal processor  130 , a scan converter  140 , an image processor  150 , a display unit  160  and an input unit  170 . The ultrasound diagnostic system  100  further includes a memory (not shown) for storing 2-dimensional ultrasound image data and 3-dimensional ultrasound image data. Also, the image signal processor  130  and the image processor  150  may be provided as one processor.  
      The probe  110  includes a 1-dimensional or a 2-dimensional array transducer  112 . The transmit signals, which are appropriately delayed in the beam former  120  to form an ultrasound beam, are transmitted to the array transducer  112 . Then, the focused ultrasound beam, which is produced in response to the transmit signals, is transmitted along a scan line of a target object (not shown). The probe  110  receives ultrasound echo signals reflected from the target object and converts the ultrasound echo signals into electrical signals (hereinafter referred to as receive signals). The receive signals are transmitted to the beam former  120 .  
      The beam former  120  provides delays of transmit signals to be transmitted to the array transducer  112  included in the probe  110  such that the ultrasound signals outputted from the array transducer  112  are focused on a focal point. Further, the beam former  120  focuses the receive signals, which are received from the array transducer  112  included in the probe  110 , in consideration of the delays with which the echo signals are arrived at each transducer. It then outputs a focused receive beam representing an energy level of the ultrasound echo signal reflected from the focal point.  
      The image signal processor  130  (e.g., a digital signal processor (DSP)) performs envelop detection for detecting intensities of the focused receive signals to form ultrasound image data. That is, the image signal processor  130  forms 3-dimensional ultrasound image data based on the receive focused signals acquired from each focal point and position information of a plurality of focal points on each scan line. The 3-dimensional ultrasound image data include coordinates information of each focal point, angle information of each scan line and intensity information of the echo signals received at each focal point.  
      The scan converter  140  scan-converts the 3-dimensional ultrasound image data to a data format capable of being displayed on a screen of the display unit  160 . The image processor  150  forms multiple sectional plane images in response to a plane selecting instruction, which is inputted by a user to determine an image slicing direction of sectional plane images. Also, the image processor  150  forms a partial 3-dimensional ultrasound image corresponding to a predetermined region of the 3-dimensional ultrasound image data in response to a region setting instruction inputted from the user. The 3-dimensional ultrasound image is displayed on the display unit  160 .  
      The input unit  170  receives user&#39;s selections to transmit the plane selecting instruction and the region setting instruction to the image processor  150 . The input unit  170  may be a mouse, a track ball, a keyboard, a touch pad or the like.  
      Hereinafter, the operation of the image processor  150  will be described in detail with reference to FIGS.  2  to  8 .  FIG. 2  is a flowchart that shows the operation of the image processor constructed in accordance with the present invention.  
      Referring now to  FIG. 2 , after forming the 3-dimensional ultrasound image data based on the ultrasound echo signals received by the probe  110  at step S 110 , the image processor  150  forms multiple sectional plane images in a predetermined image slicing direction, which is determined in response to the plane selecting instruction at step S 120 . One of the multiple sectional plane images is selected at step S 130 . The selected sectional plane image may contain images, which are desirable for diagnosis. A reference sectional plane image, which is orthogonal to the selected sectional plane image, is formed at step S 140 . The reference sectional plane image is used for setting a region representing the width of a partial 3-dimensional ultrasound image (hereinafter referred to as a 3-dimensional region) in the 3-dimensional ultrasound image data. The partial 3-dimensional ultrasound image contains images for diagnosis. For example, as illustrated in  FIG. 3 , if the selected sectional plane image is an A sectional plane image, then a B sectional plane image or a C sectional plane image becomes a reference sectional plane image. Also, if the selected sectional plane image is the B sectional plane image, then the C sectional plane image or the A sectional plane image becomes a reference sectional plane image. Further, if the selected sectional plane image is the C sectional plane image, then the A sectional plane image or the B sectional plane image becomes a reference sectional plane image.  
      The multiple sectional plane images are displayed on a multiple sectional plane image displaying part  210 , whereas the reference sectional plane image is displayed on a reference sectional plane image displaying part  220 , as shown in  FIG. 4  at step S 150 . The 3-dimensional region is set on the reference sectional plane image at step S 160 . As shown in  FIG. 5 , in order to set the 3-dimensional region, a center line  510  that represents a position of the selected sectional plane image is indicated on the reference sectional plane image  500 . The 3-dimensional region  520  is set with two lines  520 A and  520 B on the reference sectional plane image  500  to have an identical size at right and left sides of the center line  510 . The lines  520  for setting the 3-dimensional region may be straight lines or oblique lines.  
      After setting the 3-dimensional region at step S 160 , it is determined whether to slice the 3-dimensional region at step S 170 . If it is determined to slice the 3-dimensional region, then the number of slabs produced by slicing the 3-dimensional region is determined at step S 180 .  FIG. 6  shows the sliced 3-dimensional region  520  on the reference sectional plane image  500 . As shown in  FIG. 6 , four slabs are produced by slicing the 3-dimensional region along slice lines  610  and the center line  510 . The width of each slab may be identical to each other in accordance with the preferred embodiment of the present invention. Also, the width of each slab may be adjusted. The image processor  150  extracts slab data corresponding to each of the slabs from the 3-dimensional ultrasound image data at step S 190  and carries out image rendering for the extracted slab data at step S 200 , thereby forming 3-dimensional slab images  710  to  740  as shown in  FIG. 7 . The image rendering may be performed by using a volume rendering technique such as a ray casting technique or the like.  
      Further, if it is determined not to slice the 3-dimensional region at step S 170 , then the image processor  150  extracts multiple sectional plane images included within the 3-dimensional region  520  set by lines  520 A and  520 B from the multiple sectional plane images shown in  FIG. 4 . Then, the extracted multiple sectional plane images  810  are selected as shown in  FIG. 8  at step S 210 . Subsequently a region of interest (ROI)  820  is set on each of the selected multiple sectional plane images  810  at step S 220  and then the image processor  150  extracts data corresponding to the ROI from the 3-dimensional ultrasound image data. The image processor  150  carries out an image rendering process for the extracted data at step S 230 , thereby forming a 3-dimensional ultrasound image.  
      Since the 3-dimensional region to form the partial 3-dimensional ultrasound image, which contains the images desired for diagnosis, is set on the sectional plane image, the user can easily select the desirable diagnosis region in the 3-dimensional ultrasound image in accordance with the present invention.  
      Also, since a portion of 3-dimensional ultrasound data is used to form a 3-dimensional ultrasound image, the 3-dimensional ultrasound image can be formed more quickly.  
      While the present invention has been described and illustrated with respect to a preferred embodiment of the invention, it will be apparent to those skilled in the art that variations and modifications are possible without deviating from the broad principles and teachings of the present invention, which should be limited solely by the scope of the claims appended hereto.