Abstract:
A system and method for automatic segmentation, performed by selecting a deformable model of an anatomical structure of interest imaged in a volumetric image, the deformable model formed of a plurality of polygons including vertices and edges, displaying the deformable model on a display, detecting a feature point of the anatomical structure of interest corresponding to each of the plurality of polygons and adapting the deformable model by moving each of the vertices toward the corresponding feature points until the deformable model morphs to a boundary of the anatomical structure of interest, forming a segmentation of the anatomical structure of interest.

Description:
BACKGROUND 
     Traumatic Brain Injury (TBI) is one of the most common causes of long-term disability. Abnormality of several sub-cortical structures such as, for example, the corpus callosum, hippocampus, cerebellum, thalamus and caudate, have been associated with TBI. Thus, it is important to identify the neuropathology in individuals with TBI in 3D. However, methodological challenges have hampered previous studies from providing a clear pattern of structural atrophy following TBI. 
     SUMMARY OF THE INVENTION 
     A method for automatic segmentation, performed by selecting a deformable model of an anatomical structure of interest imaged in a volumetric image, the deformable model formed of a plurality of polygons including vertices and edges, displaying the deformable model on a display, detecting a feature point of the anatomical structure of interest corresponding to each of the plurality of polygons and adapting the deformable model by moving each of the vertices toward the corresponding feature points until the deformable model morphs to a boundary of the anatomical structure of interest, forming a segmentation of the anatomical structure of interest. 
     A system having a processor selecting a deformable model of an anatomical structure of interest imaged in a volumetric image, the deformable model formed of a plurality of polygons including vertices and edges and a display displaying the deformable model, wherein the processor further detects a feature point of the anatomical structure of interest corresponding to each of the plurality of polygons to deform the deformable model by moving each of the vertices toward the corresponding feature points until the deformable model morphs to a boundary of the anatomical structure of interest, forming a segmentation of the anatomical structure of interest. 
     A computer-readable storage medium including a set of instructions executable by a processor. The set of instructions operable to select a deformable model of an anatomical structure of interest imaged in a volumetric image, the deformable model formed of a plurality of polygons including vertices and edges, display the deformable member on a display, detect a feature point of the anatomical structure of interest corresponding to each of the plurality of polygons and adapt the deformable model by moving each of the vertices toward the corresponding feature points until the deformable model morphs to a boundary the anatomical structure of interest, forming a segmentation of the anatomical structure of interest. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a schematic diagram of a system according to an exemplary embodiment. 
         FIG. 2  shows a flow diagram of a method according to an exemplary embodiment. 
         FIG. 3  shows a screenshot of a deformable brain model initialized in a volumetric image displayed on a GUI. 
         FIG. 4  shows a screenshot of the deformable brain model of  FIG. 3  after it has been adapted to the volumetric image. 
     
    
    
     DETAILED DESCRIPTION 
     The exemplary embodiments may be further understood with reference to the following description and the appended drawings, wherein like elements are referred to with the same reference numerals. The exemplary embodiments relate to a system and method for segmenting brain structures. In particular, the exemplary embodiments generate a deformable model of the brain structure, which may be adapted to a volumetric image such as an MRI. It will be understood by those of skill in the art, however, that although the exemplary embodiments specifically describe segmenting brain structures, the system and method of the present invention may be used to segment any anatomical, 3-dimensional structure in a volumetric image such as, for example, an MRI and/or an ultrasound image. 
     As shown in  FIG. 1 , a system  100  according to an exemplary embodiment segments a 3D brain structure such as, for example, the corpus callosum, hippocampus, cerebellum, thalamus and caudate, of a volumetric image such as an MRI or an ultrasound image. The system  100  comprises a processor  102  that is capable of adapting a deformable model of the brain structure based on features of the structure in the image. The deformable model is selected from a database of models stored in a memory  108 . A graphical user interface  104  is utilized to input user preferences to determine a volume of the brain structure, display a deformation of the brain structure, view a particular portion of the brain structure, etc. Inputs associated with the graphical user interface are entered via, for example, a mouse, a touch display and/or a keyboard. The segmentation of the brain structure, the volumetric image and user options of the graphical user interface  104  are displayed on a display  106 . The memory  108  may be any known type of computer-readable storage medium. It will be understood by those of skill in the art that the system  100  is, for example, a personal computer, a server or any other processing arrangement. 
       FIG. 2  shows a method  200  according to an exemplary embodiment, in which the system  100  segments a brain structure to identify deformations in the brain structure. The method  200  includes selecting a deformable model of a brain structure of interest from a database of structure models stored in the memory  108 , in a step  210 . In an exemplary embodiment, the deformable model is automatically selected by the processor  102  by comparing features of the brain structure of interest in the volumetric image to the structure models in the database. In another exemplary embodiment, the deformable model is manually selected by the user browsing through the database to identify the deformable model that most closely resembles the brain structure of interest. The database of structure models may include structure models from brain structure studies and/or segmentation results from previous patients. 
     In a step  220 , the deformable model is displayed on the display  106 , as shown in  FIG. 3 . The deformable model is be displayed as a new image and/or displayed over the volumetric image. The deformable model is formed of a surface mesh including a plurality of triangularly shaped polygons, each triangularly shaped polygon further including three vertices and edges. It will be understood by those of skill in the art, however, that the surface mesh may include polygons of other shapes. The deformable model is positioned such that the vertices of the deformable model are positioned as closely as possible to a boundary of the structure of interest. In a step  230 , each of the triangular polygons is assigned an optimal boundary detection function. The optimal boundary detection function detects feature points along a boundary of the structure of interest so that each of the triangular polygons is associated with a feature point, in a step  240 . The feature points may be associated with centers of each of the triangular polygons. The feature point associated with each of the triangular polygons may be the feature point that is closest to the triangular polygon and/or corresponds to the triangular polygon in position. 
     In a step  250 , each of the triangular polygons associated with a feature point is moved toward the associated feature point such that vertices of each of the triangular polygons are moved toward the boundary of the structure of interest, deforming the deformable model to adapt to the structure of the interest in the volumetric image. The deformable model is deformed until a position of each of the triangular polygons corresponds to a position of the associated feature point and/or the vertices of the triangular polygon lie substantially along the boundary of the structure of interest, as shown in  FIG. 4 . Once the deformable model has deformed such that the triangular polygons correspond to the associated feature points of the boundary of the structure of interest, the deformable model has been adapted to the structure of interest such that the deformed deformable model represents a segmented structure of the structure of interest. 
     Upon completion of the segmentation process, the user may enter a user input, in a step  260 , regarding the segmented brain structure. The user input may be entered via the graphical user interface  104 , electing a user option, which may be displayed on the graphical user interface  104 . For example, the user may elect to enlarge and/or zoom into a particular portion of the displayed images, change a view of a particular image, determine parameters of interest (e.g., segmented structure volume, curvature at a point), identify a deformation in the segmented structure, etc. Other options may include storing the segmented structure and/or the corresponding volumetric images in the database of deformable models or recalling previously stored segmented structures from the database for comparison purposes. It will be understood by those of skill in the art that the segmented structures and/or corresponding volumetric images may also be stored within patient files to facilitate analysis of structural atrophy in TBI patients. 
     The user may desire to determine the volume and/or curvature of the segmented structure to assess changes in the brain region. Such parameters may be especially useful in linking a patient&#39;s past exposure to TBI to current sustained complaints, deficits and disability. In addition, healthy brain structures are known to be symmetrical with respect to the mid-sagittal plane such that the left and right hemispheres of the brain are mirror images of one another. Thus, in a healthy brain, a vertex in one hemisphere of the brain—in the left hemisphere, for example—should be mirrored in the other hemisphere—the right hemisphere. TBI, however, is a mostly asymmetrical disease. Thus, deviations from mean vertex values represent variances that indicate a severity of deformation of brain structures of interest. The user may therefore elect to view the deviations from mean vertex values of the segmented structure. In a further embodiment, different deviations may be color-coded for easy visualization and interpretation of results. 
     In a step  270 , the processor  102  generates a response to the user input entered in the step  260 . For example, if the user has requested the segmented structure volume, the processor  102  will calculate the volume and display the volume on the display  106 . If the user has indicated the user would like to enlarge a particular portion of the volumetric image and/or segmented organ, the processor  102  will generate and display an enlarged view of the particular portion desired. In another example, if the user has indicated that the user would like to identify deformations in the segmented structure, the processor  102  will identify a mid-sagittal plane, identify deviations in mean vertex values between the left and right hemispheres and display the deformations on the display  106 . As described above, the different deviations may be color-coded. The steps  260 - 270  may be repeated as desired, until the user has elected all desired options in regard to the segmented structure of the brain. 
     It will be apparent to those skilled in the art that various modifications and variations can be made in the structure and methodology described herein. Thus, it is intended that the present disclosure cover any modifications and variations provided that they come within the scope of the appended claims and their equivalents. 
     It is also noted that the claims may include reference signs/numerals in accordance with PCT Rule 6.2(b). However, the present claims should not be considered to be limited to the exemplary embodiments corresponding to the reference signs/numerals.