Abstract:
The invention relates to generating a composite medical image combining at least first and second image data. Particularly, the invention relates to a medical imaging system for generating a composite medical view or image combining at least first and second image data as well as a method for generating a composite medical image. In order to provide a combination of image data providing improved perceptibility and enhancing the use of acquired image data, a medical imaging system for generating a composite medical view/image combining at least first and second image data, comprising an image acquisition device, a data processing unit and a display device, a medical imaging system and a method for generating a composite medical image combining at least first and second image data provided, the method comprising the following steps: a) selecting first image data of a first image ( 212 ) and second image data of a second image ( 214 ); b) registering the first and the second image data; c) determining a boundary connecting sector connecting adjacent boundaries of the first image and the second image; d) generating a separator ( 218 ) on behalf of the image data of the boundary connecting sector; e) combining image data of the first image and the second image with image data of the separator to a combined image data; and f) displaying the combined image comprising the separator ( 218 ).

Description:
FIELD OF THE INVENTION 
       [0001]    The invention relates to generating a composite medical view combining at least first and second image data. Particularly, the invention relates to a medical imaging system for generating a composite medical image combining at least first and second image data as well as a method for generating a composite medical view. 
       BACKGROUND OF THE INVENTION 
       [0002]    In clinical applications, a single view or image may not be sufficient to view or image the complete desired body region. Thus, two or more, in other words, multiple, scans are combined to represent the full desired body region. The necessity to combine several images may for example be due to image acquisition aspects, such as the size of available image detectors. For example, the size and resolution of X-ray images is defined among other aspects primarily by the size of the detector. The step of combining several images is also referred to as stitching images together. But it has been shown that due to different reasons, for example due to artefacts or movement during the image acquisition, two adjacent images may not perfectly connect at their contacting edges. These contacting edges are also referred to as interface of the two adjacent images. The eye is very sensitive in identifying discontinuities along a straight interface and even very small jumps in intensity may be deemed unacceptable, for example by surgeons in a hospital. However, differences in intensity along the interface can induce a sense of (sometimes serious) image artifacts, more than is warranted by the actual intensity jump over the interface. Further, differences in intensity along the interface, may also add to fatigue and even loss of concentration with respect to the user, for example clinical staff. Therefore, it is known to blend two images together in an overlap region. But this requires a larger image area than the actual image area used for the combination, in other words, the step of blending images requires more individual images because of the necessary overlap. Another disadvantage is that blending images together may remove or distort clinically relevant data. 
       SUMMARY OF THE INVENTION 
       [0003]    Hence, there may be a need to provide a combination of image data providing improved perceptibility and enhancing the use of acquired image data. 
         [0004]    According to an exemplary embodiment of the invention, a method for generating a composite medical view combining at least first and second image data is provided that comprises the following steps: a) selecting first image data of a first image and second image data of a second image; b) registering the first and second image data; c) determining a boundary connecting sector connecting adjacent boundaries of the first image and the second image; d) generating a separator on behalf of the image data of the boundary connecting sector; e) combining image data of the first image and the second image with image data of the separator to a combined image data; and f) displaying the combined image comprising the separator. 
         [0005]    The separator provides the effect that the two image regions are visually decoupled because the separator represents the boundary connecting sector connecting adjacent boundaries of the first image and the second image. Thus, the separator provides the possibility to effectively remove the visibility of small discontinuities normal to the separator. Differences in the intensity of the two adjacent image regions are not visible any more. Further, patient data contained in the acquired image data is not being removed as is the case, for example, when blending images together in an overlap region. As a further advantage, the user, for example a physician is provided with information where two or more volume segments are connected. This information is provided by displaying the separator in the combined image. 
         [0006]    It is noted that according to another exemplary embodiment, the term view relates to, for example, an image, such as an image displayed on a monitor. 
         [0007]    According to another exemplary embodiment, the term view refers to a projection of a 3D volume. 
         [0008]    Hence, the terms first and second image data refers to both data for 2D images and dada for 3D volumes. 
         [0009]    In another exemplary embodiment, the image data is two-dimensional image data. For example, the separator can be a straight or curved or otherwise shaped line. 
         [0010]    In a further exemplary embodiment, the image data is three-dimensional image data. For example, the separator can be a straight plane or a curved or otherwise shaped spatial layer. 
         [0011]    In a further exemplary embodiment, the separator can present the interface of two adjacent volumes. 
         [0012]    In a further exemplary embodiment, the separator can present the area or space between the two adjacent volumes, for example, in case the first and second image data are registered such that a gap exists between the two images. For example, the gap can have the shape of a wedge, thus leading to a boundary connecting sector having the form of a wedge, too. It is then possible, for example, to generate a separator following the wedge-like form of a boundary connecting sector. 
         [0013]    In another exemplary embodiment, the separator can be adapted such that a misleading or disturbing form of the boundary connecting sector is at least partially equalled. 
         [0014]    According to another exemplary embodiment, the combined image can be a combination of more than two images, for example, three or four images. The image can be combined, for example, out of images arranged one next to another, for example, in a row. The images can also be arranged in a certain pattern, such as around a center point. 
         [0015]    According to another exemplary embodiment, a method is provided wherein the step c) of determining the boundary connecting sector comprises the following sub-steps. First, a common image region of the first image data overlapping with the second image data is determined and the common image region of the second image data overlapping with the first image data is determined. Next, cutting data in the common image regions is determined. Then, the first image data is adapted by cutting the first image data according to the cutting data removing the overlapping region of the first image data and the second image data is adapted by cutting the second image data according to the cutting data removing the overlapping region of the second image data. Further, the cutting data is determined as boundary connecting sector. Still further, the separator is generated adapted to the cutting data. 
         [0016]    By determining the overlap of images to be combined, it is also possible to use images which have been acquired according to conventional acquisition procedures where it is common to provide an overlap of the images. As an advantage, the step of blending commonly used in such cases is not necessary any more. 
         [0017]    According to an exemplary embodiment, the cutting data can be a cutting plane in case the image data is three-dimensional image data or a cutting line in case of two-dimensional image data. 
         [0018]    According to another exemplary embodiment, the step e) of combining image data of the first image and the second image with image data of the separator to the combined image data comprises a step of displacing the adapted first image data and the adapted second image data in relation to each other and the step of locating the separator such that the separator is located at least outside the adapted first image. 
         [0019]    According to a further exemplary embodiment, the separator can also be located outside the adapted second image, in other words, between the first and the second image. 
         [0020]    This provides the possibility to show both the image parts to be combined and the separator without hiding any clinically relevant data contained in the acquired image data. 
         [0021]    According to another exemplary embodiment, the image data is two-dimensional image data. 
         [0022]    For example, the 2D image data can be a projection of three-dimensional volume information. 
         [0023]    For example, the image data can be acquisition by X-ray, such as a BrightView XCT scan. 
         [0024]    According to another exemplary embodiment, the separator is a line. 
         [0025]    A line provides a separator minimizing the risk of misleading interpretation by the user. 
         [0026]    For example, the separator can be adapted to the adjacent image data. For example, the line can be adapted concerning brightness or colour. For example, in an image with a dark back ground showing image information in rather bright colors, the separator can be shown in bright colors or in a brighter grey scale value in case of a grey scale image. 
         [0027]    According to another exemplary embodiment, the separator is a striped line. 
         [0028]    According to another exemplary embodiment, the line can be a dotted line. 
         [0029]    Dotted or striped lines give the greatest sense of observing an uninterrupted volume to the user, while still visually hiding discontinuities of the combined image halves. 
         [0030]    According to another exemplary embodiment, the separator is a coloured line. Also, a coloured and striped line may be used. Further, for example, the line can be adapted to the location on the screen or the image to fulfill its function of hiding or reducing discontinuities along the interface due to the particular sensitivity of the user&#39;s eye. For example, the line can be differently adapted along its extension. 
         [0031]    According to an exemplary embodiment the separator can be adapted along its extension in relation to the adjacent image content, for example depending on image parameters such as brightness, contrast or colours etc. 
         [0032]    According to an exemplary embodiment of the invention, a medical imaging system for generating a composite medical view or image, combining at least first and second image data is provided comprising an image acquisition device, a data processing unit and a display device. The image acquisition device is arranged to acquire at least a first and second image. The data processing unit is adapted to receive first image data of a first selected image and second image data of a selected second image from the image acquisition device. The data processing unit is further adapted to register the first and the second image data. The data processing unit is adapted to determine a boundary connecting sector, connecting adjacent boundaries of the first image and the second image and to generate a separator on behalf of the image data of the boundary connecting sector. The data processing unit is further adapted to combine image data of the first image and the second image with image data of the separator to a combined image data. The display device is arranged to display the combined image comprising the separator. 
         [0033]    According to another exemplary embodiment, an interface unit is provided, which interface unit is adapted for the selection of the first image and the second image by the user. 
         [0034]    According to an exemplary embodiment, the data processing unit is adapted to determine a common image region of the first image data overlapping with the second image data and to determine a common image region of the second image data overlapping with the first image data. The data processing unit is also adapted to determine cutting data in a common image region and to adapt the first image data by cutting the first image data according to the cutting data removing the overlapping region of the first image data and to adapt the second image data by cutting the second image data according to the cutting data removing the overlapping region of the second image data. The data processing unit is further adapted to determine the cutting data as boundary connecting sector and to generate the separator adapted to the cutting data. 
         [0035]    According to an exemplary embodiment, the image acquisition device is an X-ray acquisition device. 
         [0036]    For example the X-ray acquisition device is an XCT scan. The image data can be two-dimensional image data. For example, the 2D image data can be a projection of three-dimensional volume information acquired by an X-ray image acquisition process. 
         [0037]    In another exemplary embodiment of the present invention, a computer program or a computer program element is provided that is characterized by being adapted to execute the method steps of the method according to one of the preceding embodiments, on an appropriate system according to one of the preceding embodiments. 
         [0038]    The computer program element might therefore be stored on a computer unit, which might also be part of an embodiment of the present invention. This computing unit may be adapted to perform or induce a performing of the steps of the method described above. Moreover, it may be adapted to operate the components of the above-described apparatus. The computing unit can be adapted to operate automatically and/or to execute the orders of a user. A computer program may be loaded into a working memory of a data processor. The data processor may thus be equipped to carry out the method of the invention. 
         [0039]    This exemplary embodiment of the invention covers both, a computer program that right from the beginning uses the invention and a computer program that by means of an up-date turns an existing program into a program that uses the invention. 
         [0040]    Further on, the computer program element might be able to provide all necessary steps to fulfill the procedure of an exemplary embodiment of the method as described above. 
         [0041]    According to a further exemplary embodiment of the present invention, a computer readable medium, such as a CD-ROM, is presented wherein the computer readable medium has a computer program element stored on it which computer program element is described by the preceding section. 
         [0042]    However, the computer program may also be presented over a network like the World Wide Web and can be down loaded into the working memory of a data processor from such a network. According to a further exemplary embodiment of the present invention, a medium for making a computer program element available for down loading is provided, which computer program element is arranged to perform a method according to one of the previously described embodiments of the invention. 
         [0043]    It has to be noted that embodiments of the invention are described with reference to different subject matters. In particular, some embodiments are described with reference to method type claims whereas other embodiments are described with reference to the device type claims. However, a person skilled in the art will gather from the above and the following description that, unless otherwise notified, in addition to any combination of features belonging to one type of subject matter also any combination between features relating to different subject matters is considered to be disclosed with this application. However, all features can be combined providing synergetic effects that are more than the simple summation of the features. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0044]    The aspect defined above and further aspects, features and advantages of the present invention can also be derived from the examples of embodiments to be described herein after and are explained with reference to examples of embodiments, but to which the invention is not limited. The invention will be described in more detail hereinafter with reference to the drawings. 
           [0045]      FIG. 1  schematically shows a medical imaging system; 
           [0046]      FIG. 2  schematically shows basic steps of a method for generating a composite medical view or image; 
           [0047]      FIG. 3  schematically shows sub steps of an exemplary embodiment of the method shown in  FIG. 2 ; 
           [0048]      FIG. 4  shows additional sub steps of the methods shown in  FIGS. 2 and 3 ; 
           [0049]      FIG. 5  shows an exemplary embodiment of  2  connecting images with discontinuities in intensity along a straight interface; 
           [0050]      FIG. 6  shows the two adjacent images of  FIG. 5  in a combined image comprising a separator; 
           [0051]      FIG. 7  schematically shows another example of two adjacent images with intensity differences along a horizontal interface; 
           [0052]      FIG. 8  schematically shows a combined image, according to the invention, based on the images shown in  FIG. 7 , comprising a separator; 
           [0053]      FIG. 9  shows another example for two adjacent images with discontinuities in intensity along a horizontal interface; 
           [0054]      FIG. 10  shows a combined image, according to the invention, comprising a separator, based upon the images shown in  FIG. 9 ; 
           [0055]      FIGS. 11 to 16  show photographic images of X-ray images according to  FIGS. 5 to 10  respectively; 
           [0056]      FIG. 17  schematically shows sub steps of an embodiment of the method, shown in  FIGS. 2 to 4 ; and 
           [0057]      FIG. 18  schematically shows a boundary connecting sector of two adjacent images and the separator generated on behalf of the boundary connecting sector. 
       
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
       [0058]      FIG. 1  schematically shows a medical imaging system  10  for generating a composite medical view/image, combining at least first and second image data. The medical imaging system  10  comprises an image acquisition device  12 , a data processing unit  14  and a display device  16 . 
         [0059]    It is noted that the term view relates to, for example, an image, such as an image displayed on a monitor. Further, the term view also refers to a projection of a 3D volume. Still further, the terms first and second image data refers to both data for 2D images and dada for 3D volumes. 
         [0060]    For example, the medical imaging system is an X-ray imaging system, comprising a source of X-ray radiation  18  provided to generate X-ray radiation. A table  20  is provided to receive a subject to be examined, for example a patient  22 . Further, an X-ray image detection module  24  is located opposite the source of X-ray radiation  18 , i.e. during the radiation procedure, a subject is located between the source of X-ray radiation  18  and detection module  24 . The latter is sending data to the data processing unit  14  which is connected to both, the detection module  24  and the radiation source  18 . The data processing unit  14  is located in the vicinity of the table  20 , for example integrated into a common housing. Of course, it could also be located at different places, such as a different room. Furthermore, the display  16  is arranged in the vicinity of the table  20  to display information to a person operating the X-ray imaging system, for example a clinician such as a surgeon or a cardiologist, for example. Preferably, the display device  16  is movably mounted to allow for an individual adjustment, depending on the examination situation. Also, an interface unit  26  is arranged to input information or commands by the user. Basically, the image detection module  24  generates image data by exposing the subject to X-ray radiation, wherein said images are further processed in the data processing unit  14 . It is noted that the example shown is a so-called CT-type X-ray image acquisition device. Of course, the invention also relates to other types of X-ray image acquisition devices, such as C-type X-ray image acquisition devices. Of course, instead of using X-ray radiation to acquire image data, the invention also relates to other image acquisition procedures, such as photography or ultrasound imaging. 
         [0061]    The image acquisition device  12  is arranged to acquire at least a first and a second image. The data processing unit  14  is adapted to receive first image data of a first selected image and second image data of a selected second image from the image acquisition device, to register the first and the second image data, to determine a boundary connecting sector connecting adjacent boundaries of the first image and the second image, to generate a separator on behalf of the image data of the boundary connecting sector, and to combine image data of the first image and the second image with image data of the separator to combine image data. The display device  16  is arranged to display the combined image comprising a separator. The procedure, according to the invention is described in more detail below. 
         [0062]      FIG. 2  schematically shows basic method steps for generating a composite medical image, combining at least first and second image data. First, image data of a first image  112  and second image data of a second image  114  are selected in a step  116 . For example, these images  112 ,  114  may have been acquired prior to the selecting step in an image acquisition procedure  118 . This image acquisition procedure can also be referred to as a prior step that is a step performed independent of the other method steps. In exemplary embodiment, the image acquisition step  118  may also be referred to as a part of the method steps. 
         [0063]    Further, in a registration step  120 , the first and the second image data are registered. Then, in a determination step  122 , a boundary connecting sector connecting adjacent boundaries of the first image  112  and the second image  114  is determined. Then, in a generating step  124 , a separator is generated on behalf of the image data of the boundary connecting sector. In a combining step  126 , image data of the first image and the second image is combined with image data of the separator to a combined image data  128 . Further, in a display step  130 , the combined image comprising the separator is displayed. 
         [0064]    For example, the image data can be two-dimensional image data such that the separator can be a straight or curved line. 
         [0065]    In case the image data is a three-dimensional image data, the separator can be a straight or curved or otherwise shaped plane. 
         [0066]    The separator can present the interface of two adjacent volumes. 
         [0067]    Of course, the combined image can be a combination of more than two images, for example three or four images. The image can be combined, for example out of images arranged one next to another, for example in a row, or arranged in certain patterns, such as a round or center point. 
         [0068]      FIG. 3  shows an exemplary embodiment of the steps  122  and  124 . According to this exemplary embodiment, the step  122  of determining the boundary connecting sector comprises several sub steps, as described in the following. Following to the step  120  of registering the first and the second image data, in a determining step  132 , a common region of the first image data overlapping with a second image data is determined and an image region of the second image data overlapping with the first image data is also determined. Next, in a determining step  134 , cutting data the common image region is determined. Then, in an adapting step  136 , the first image data is adapted by cutting the first image data according to the cutting data removing the overlapping region of the first image data and the second image data is adapted by cutting the second image data according to the cutting data removing the overlapping region of the second image data. Further, in a determining step  138 , the cutting data is determined as a boundary connecting step. Further, the step  124  of generating the generator comprises generating the separator adapted to the cutting data. Finally, the combined image data comprising the separator is displayed in the display in step  130 . 
         [0069]      FIG. 4  shows another exemplary embodiment of the method, basically described in  FIG. 2 . Following the generating step  124  of  FIG. 2 , referring to generating a separator on behalf of the image data of a boundary connecting sector, or also following the determination step  140  described in  FIG. 3 , referring to the generating step, comprising generating the separator adapted to the cutting data, the step  128  of combining image data of the first image and the second image with image data of the separator to the combined image data comprises a displacing step  142  where the adapted first image data and the adapted second image data are displaced in relation to each other and the separator is located such that the separator is located outside the adapted first image. Further, the displaying step  130  is provided to display the combined image comprising the separator. 
         [0070]    According to an example, the separator can also be located outside the adapted second image, in other words, between the first and the second image. 
         [0071]      FIGS. 5 to 10  show exemplary embodiments of two adjacent images having discontinuities along a straight interface which in the  FIGS. 5 to 10  is arranged horizontally. For a better understanding, the two images are shown adjacent to each other in one example and as a combined image comprising a separator according to the invention. 
         [0072]    A first example is shown in  FIGS. 5 and 6 , showing two images  212  and  214  arranged as horizontal stripes with a strict interface  216  showing discontinuities in intensity which may be deemed unacceptable by a user. According to the invention, a separator  218  is provided in  FIG. 6 , eliminating or at least significantly reducing the visible discontinuities along the straight interface  216 . In the example shown in  FIG. 6 , the separator  218  is shown as a medium line, for example in a colour not used in the combined images  212  and  214 . For example, in case the images  212  and  214  are X-ray images shown in a grey scale value, the separator  218  can be shown as a yellow line. 
         [0073]    According to the example shown in  FIGS. 7 and 8 ,  FIG. 7  shows a first image  312  and a second image  314  arranged underneath connected by a straight interface  316  arranged in a horizontal direction. As can be seen, the two images  312  and  314  show differences in their intensity although the adjacent image regions refer to the same body region. According to the invention, a separator  318  is shown in  FIG. 8  displaying the combined image comprising the separator  318 . In this example, the separator  318  is shown as a solid white thin line. 
         [0074]    In a further exemplary shown in  FIGS. 9 and 10 , a first image  412  and a second image  414  are arranged adjacent to each other, connected by an interface  416 . The interface  416  can be identified in  FIG. 9  due to the different image intensities along the straight interface  416 . According to the invention, after selecting the first image data of a first image  412  and second image data of a second image  414  and registering the first and the second image data, a boundary connecting sector is determined connecting adjacent boundaries of the first image  412 , the second image  414 . According to the example shown, the boundary connecting sector is a straight line, also referred to as a straight interface  416 . Then, a separator  418  is generated on behalf of the image data of the boundary connecting sector, i.e. on behalf of the image data of the straight interface  416 . Further, the image data of the first image  412  and the second image  414  is combined with image data of the separator  418  to a combined image data shown as a combined image  420  in  FIG. 10  comprising the separator  418 . For example, the separator  418  in  FIG. 10  is shown as a striped line. The striped line provides the effect that a good sense of observing an uninterrupted volume is given, while still hiding discontinuities. 
         [0075]    For an even better understanding,  FIGS. 11 to 16  show photographic images of  FIGS. 5 to 10  showing X-ray images arranged adjacent to each other in relation to a combined image comprising a separator, wherein the combined image is shown underneath the adjacently arranged images. 
         [0076]    According to a further exemplary embodiment, the step of determining the boundary connecting sector of a first image  512  and a second image  614  comprises the following sub steps. As can be seen in  FIG. 17 , a common image region  516  of the first image data  512  overlapping with the second image data  514  is determined. Further, a common image region  518  of the second image data  514  overlapping with the first image data  512  is determined. Next, cutting data is determined in the common image region. In the example shown, the cutting data is a cutting line  520  in the first image  512  and a cutting line  522  in the second image  514 . Next, a first image data  512  is adapted by cutting the first image data according to the cutting data that is according to the cutting line  520  removing the overlapping region  516  of the first image  512 . The second image  514  is adapted by cutting the second image data  514  according to the cutting line  522  removing the overlapping region  518  of the second image  514 . Thus, an adapted first image  512 ′ and an adapted second image  514 ′ are provided. Further, the cutting data is determined as boundary connecting sector and the separator is generated adapted to the cutting data. Still further, the image data of the first adapted image  512 ′ is combined with the image data of the adapted image  514 ′ together with a separator  524  and the combined image is displayed on the display. 
         [0077]    According to another exemplary embodiment of the invention, the separator can be shown not only as a thin line, but also in other geometric forms, in case the image data is a two-dimensional image. 
         [0078]    As a further example,  FIG. 18  shows a first image  612  and a second image  614 . The two images  612 ,  614  are already registered in  FIG. 18 . Nevertheless, a boundary connecting sector  616  has been determined connecting the adjacent boundaries of the first image  612  and the second image  614 . As can be seen, the boundary connecting sector  616  has a form of a wedge which might be due, for example, to misalignment during the image acquisition procedure. However, in order to present an easily understandable image without disturbing graphical elements, such as discontinuities in the intensity for example, a separator  618  is generated on behalf of the image data of the boundary connecting sector  616 . The separator  618  is adapted to both the boundary connecting sector  616  and to aspects relating to visible conceptance of image contents. The separator  618  is a thicker horizontal line separating the first image  612  and the second image  614 . Due to the separator  618 , differences in the intensity, for example, are not visible any more to the user. Further, since the separator is covering the wedge-like boundary connecting sector  616 , indicated by a dotted line  620 , no disturbing lines, such as small deviations in the angle or horizontal plane are shown. Thus, an image is provided covering a larger image area than just showing one image, wherein the discontinuities are removed with respect to the sense of observing an uninterrupted volume. 
         [0079]    According to a further exemplary embodiment, not shown in the figures, the image data is three-dimensional image data and a separator is a volume that is a boundary volume connecting the adjacent volumes of the first image data and the second image data. Accordingly, the separator is, for example, a layer or plane in space that can be displayed according to the type of graphical display chosen for the three-dimensional representation on a two-dimensional stream. 
         [0080]    While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive. The invention is not limited to the disclosed embodiments. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing a claimed invention, from a study of the drawings, the disclosure, and the dependent claims. 
         [0081]    In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. A single processor or other unit may fulfill the functions of several items re-cited in the claims. The mere fact that certain measures are re-cited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. 
         [0082]    A computer program may be stored and/or distributed on a suitable medium, such as an optical storage medium or a solid state medium supplied together with or as part of other hardware, but may also be distributed in other forms, such as via the internet or other wired or wireless telecommunication systems. 
         [0083]    Any reference signs in the claims should not be construed as limiting the scope.