Abstract:
In a method for the presentation of images of a region that are generated in a chronological sequence the values allocated to the picture element per image are compared to one another for acquiring changes for at least one picture element that represents an identical location per image with respect to the region to be imaged, the acquired changes are set down in a change log for the picture element, a marking is allocated to the picture element dependent on the change log, and the marking is superimposed on the location of the picture element in a selected image of the region.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention is directed to a method for the presentation of images of an imaged region that are generated in a chronological succession.  
           [0003]    2. Description of the Prior Art  
           [0004]    In a functional magnetic resonance imaging, for example, images of a brain are registered in a chronological sequence. The objective of functional magnetic resonance imaging is to acquire a functional image for the identification of active brain areas. To that end, images with and without a specific neural activity of the brain are registered in succession at different points in time. For forming the functional image, the images generated with the neural activity are compared to those without neural activity to determine differences in order to identify active brain areas. To insure that the functional image contains reliable information, many images with and without neural activity must be registered because images are obtained on the basis of the comparatively weak BOLD (Blood Oxygen Level Dependent) effect using magnetic resonance technology and must be processed, such as by averaging, during the comparison procedure. Since even slight positional changes of the brain during an overall exposure time span of the functional magnetic resonance imaging lead to unwanted signal differences that mask the sought brain activity, the images are usually brought into the best possible coincidence before the comparison using suitable methods. Further details regarding functional magnetic resonance imaging are set forth, for example, in the article by U. Klose et al., “Funktionelle Bildgebung mit der Magnet-resonanztomographie”, electromedica 67 (1999), No. 1, pages 27 through 36.  
           [0005]    For the different purpose of monitoring a therapy for destroying a tumor, for example, medical diagnostic images of a region of a patient containing the tumor are generated between time segments of the therapy. The change in the size of the tumor can be derived from common observation of the images that are produced. How precisely and how quickly the change in size can be read from the images is highly dependent on the respective expertise and experience of a viewer, for example an attending physician.  
         SUMMARY OF THE INVENTION  
         [0006]    It is an object of the present invention to provide an improved method for presenting images of a region to be imaged that are generated in a chronological sequence, with which, among other things, a simple recognition of time differences between the images is enabled.  
           [0007]    This object is achieved in accordance with the invention in a method for the presentation of images of a region that are generated in a chronological sequence wherein respective values allocated to picture elements per image are compared to one another for acquiring changes in at least one picture element that represents an identical location per image with respect to the region to be imaged, the acquired changes are entered in a change log for the picture element, a marking is allocated to the picture element dependent on the change log, and the marking is superimposed on the location of the picture element in a selected image of the region to be imaged.  
           [0008]    All changes that occur during the sequence thus can be presented in a single image and thus can be simply and reliably recognized. A physician supervising a tumor therapy, for example, can immediately see in what way a tumor has developed over time during the course of the therapy and how the therapy is to be subsequently continued in an appropriate way.  
           [0009]    In an embodiment, a minimum difference between two values to be compared is presumed for one of the changes. This prevents imprecisions when generating the images from leading to an incorrect designation as change.  
           [0010]    In another embodiment, the images are brought into coincidence before the comparison. This assures that the compared picture elements per image represent an identical location with respect to the region to be imaged. To that end, the methods cited earlier for functional magnetic resonance imaging can be applied. 
       
    
    
     DESCRIPTION OF THE DRAWINGS  
       [0011]    [0011]FIG. 1 illustrates the matrix structure of an image of the type to be processed and presented in accordance with the inventive method.  
         [0012]    [0012]FIGS. 2 through 4 respectively illustrate first, second and third images of a region for explaining the inventive method.  
         [0013]    [0013]FIGS. 5 and 6 respectively illustrate first and second difference image for explaining the inventive method.  
         [0014]    [0014]FIGS. 7 and 8 respectively illustrate first and a second gradient image for explaining the inventive method.  
         [0015]    [0015]FIG. 9 illustrates a superimposed image for explaining the inventive method.  
         [0016]    [0016]FIG. 10 illustrates an anatomical image that has a gradient image superimposed on it in accordance with the inventive method.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0017]    [0017]FIG. 1 shows a matrix structure  11  of a gray scale image composed of twenty-five picture elements V 11  through V 55 . Each of the picture elements V 11  through V 55  can assume a value in a prescribable gray scale.  
         [0018]    [0018]FIGS. 2 through 4 respectively show first, second and third images  1  through  3  of the same region of a subject. The images  1  through  3  have the matrix structure  11  illustrated in FIG. 1. For a simple explanation, only a two-level gray scale has been allocated to images  1  through  3 , so that the picture elements V 11  through V 55  of the images  1  through  3  can only be black or white. The images  1  through  3  are registered in a chronological sequence, with prescribable time segments between the registration times of the individual images  1  through  3 . The region to be imaged is, for example, a region of a patient having a tumor. Picture elements that image regions of the tumor in images  1  through  3  are black and the picture elements imaging the healthy tissue regions are white.  
         [0019]    In the first image  1 , the tumor extends over the picture elements V 22  through V 24 , V 32  through V 34  and V 42  through V 44 . Following the registration time of the first image  1 , for example, a first segment of a radiation therapy for combating the tumor is implemented. The second image  2  is registered after the first segment of the radiation therapy. Compared to the first image  1 , one can see in the second image  2  that the picture elements V 42  and V 43  change from black to white, i.e. the tumor has been successfully radiation-treated in these regions. In contrast thereto, the picture element V 25  changes from white to black, i.e. the tumor has expanded in this region.  
         [0020]    Following the registration time of the second image  2 , a further segment of the radiation therapy is implemented. The third image  3  is registered following thereupon. Given a comparison of the third image  3  to the images  1  and  2 , the following changes can be found. The picture element V 42  changing from black to white from image  1  to image  2  again changes from white to black from image  2  to image  3 . The picture elements V 22 , V 32  through V 34  and V 45  for the first time change from black to white from image  2  to image  3 . The picture element V 25  that changes from white to black from image  1  to image  2  changes back from black to white from image  2  to image  3 . Further, the picture elements V 14  and V 15  of image  2  change from white to black for the first time in image  3 .  
         [0021]    Images  1  through  3  are initially combined with one another so that the preceding changes can be visualized in a single image. To that end, a first difference image  12  shown in FIG. 5 is formed between the images  1  and  2  in that the second image  2  is subtracted from the first image  1 . Those picture elements wherein a change from black to white occurs from the first image  1  to the second image  2  are identified with an upwardly directed hatching having a first density. These are the picture elements V 42  and V 43  in the first difference image  12 . Further, those picture elements wherein a change from white to black occurs from the first image  1  to the second image  2  are identified in the first difference image  12  with a downwardly directed hatching of the first density. This is the picture element V 25  in the first difference image  12 . Picture elements that do not change from the first image  1  to the second image  2  remain free of a marking in the first difference image  12 .  
         [0022]    [0022]FIG. 6 shows a second difference image  13  between the first image  1  and the third image  3 . Those picture elements that change from black to white from the first image  1  to the third image  3  are identified with an upwardly directed hatching having a second density. These are the picture elements V 22 , V 32  through V 34 , V 43  and V 44  in the second difference image  13 . The second density is higher than the first density. Further, those picture elements that change from white to black from the first image  1  to the third image  3  are identified with a downwardly directed hatching having the second density. In the second difference image  13 , these are the picture elements V 14  and V 15 . Picture elements that do not change from the first image  1  to the third image  3  remain free of a marking in the second difference image  13 .  
         [0023]    [0023]FIG. 7 shows a first gradient image  21  that results from a superimposition of the first and second difference images  12  and  13 . The superimposition is implemented such that the marking of the second difference image is employed given the presence of a marking in the first as well as in the second difference images  12  and  13 . The picture element V 43  in the first gradient image  21  thus exhibits an upwardly directed hatching having the second density.  
         [0024]    [0024]FIG. 8 shows a further gradient image  22  that results from a superimposition of the first and second difference images  12  and  13 . Differing from the first gradient image  21 , the markings of the first difference image  12  thereby dominate, so that the picture element V 43  in the second gradient image  22  has an upwardly directed hatching of the first density.  
         [0025]    In other embodiments, picture elements that change multiply between images comparable to the picture elements V 43  are identified in the gradient image with a different hatching, for example a cross-hatching. In another embodiment, colors are employed as markings. The colors can thereby be freely selected by the user.  
         [0026]    In another step, the gradient images  21  and  22  are superimposed on a selected image. FIG. 9 shows a superimposed image  31 , with the first image  1  employed as the selected image as an example, the first gradient image  21  being superimposed thereon.  
         [0027]    In another embodiment, a gradient image is superimposed on an anatomical image of the region to be imaged. The anatomical image can exhibit a higher resolution than the images employed to generate the gradient image. To that end, FIG. 10 shows an anatomical image  41  of a sagittal slice of a human brain generated with magnetic resonance technology on which a gradient image  25  is superimposed. A relationship between the anatomy and the chronological changes has thus been produced.  
         [0028]    Not only active and inactive brain regions, but also chronological changes of brain activities can be presented in functional magnetic resonance imaging in accordance with the invention.  
         [0029]    Although modifications and changes may be suggested by those skilled in the art, it is in the intention of the inventor to embody within the patent warranted hereon all changes and modifications as reasonably and properly come within the scope of his contribution to the art.