Abstract:
A system and method directed to receiving a first data set corresponding to patient data at a first time, receiving a second data set corresponding to patient data at a second time, segmenting a first region of interest in the first data set and a second region of interest in the second data set, the first and second regions corresponding to one another and aligning the first region of interest with the second region of interest to highlight a first contour indicating a change in size, shape and orientation between the first and second regions of interest.

Description:
CROSS-REFERENCE TO PRIOR APPLICATIONS 
     This application is the U.S. National Phase application under 35 U.S.C. §371 of International Application No. PCT/IB2014/060153, filed on Mar. 26, 2014, which claims the benefit of U.S. Patent Application No. 61/806,046, filed on Mar. 28, 2013. These applications are hereby incorporated by reference herein. 
    
    
     BACKGROUND 
     For many medical applications and examinations, it is useful to track the progress of tissue growth and/or shrinkage in the brain (e.g., to monitor brain atrophy in patients having neurodegenerative diseases, to determine a response of a cancerous tumor to treatment, etc.). To perform a diagnosis, a physician or other user typically compares the shape of the brain in a current brain scan to the shape from a previous brain scan. However, in many cases, the structural changes in the brain over time are subtle and therefore difficult to recognize. It therefore becomes cumbersome to properly assess an efficacy of a treatment or to track brain atrophy. There may be a need for an efficient process by which to streamline an analysis between different images. 
     SUMMARY 
     A system and method directed to receiving a first data set corresponding to patient data at a first time, receiving a second data set corresponding to patient data at a second time, segmenting a first region of interest in the first data set and a second region of interest in the second data set, the first and second regions corresponding to one another and aligning the first region of interest with the second region of interest to highlight a first contour indicating a change in size, shape and orientation between the first and second regions of interest. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Several exemplary embodiments of the invention will be described in the following by way of example and with reference to the accompanying drawings in which: 
         FIG. 1  depicts an overlay image according to a first exemplary embodiment; 
         FIG. 2  depicts an overlay image according to a second exemplary embodiment; 
         FIG. 3  depicts an overlay image according to a third exemplary embodiment; 
         FIG. 4  depicts an overlay image according to a fourth exemplary embodiment; 
         FIG. 5  depicts an exemplary method for generating an overlay; and 
         FIG. 6  shows a schematic drawing of a system according to an exemplary embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     The exemplary embodiments may be further understood with reference to the following description and appended drawings. The exemplary embodiments relate to an interactive visualization mode displaying structures in the brain captured via any imaging modality including, but not limited to, functional magnetic resonance imaging (fMRI), computed tomography (CT), Positron Emission Tomography (PET), magnetoencephalography (MEG) or any other imaging technique known in the art and with any therapy planning workstations including, but not limited to ViewForum, Pinnacle, FEW, etc. It is noted that although the exemplary embodiments are discussed with respect to imaging of the brain, the exemplary system and method may be applied to the imaging of any other anatomical region without deviating from the scope of this disclosure. The exemplary system and method provides a visualization mode wherein first and second images may be provided in an overlay with one another to aid in visualization of variations in structures therebetween. The first image may be captured at a baseline time period and recorded onto a storage medium along with details with respect to patient state, time of image capture, etc. The second image may be captured after any of a lapse of a predetermined time period, administration of a treatment, occurrence of a major medical event (e.g., stroke, etc.), or any other time period of interest and may be stored on a storage medium along with patient details. The exemplary system and method can perform a segmentation of structures of interest in each of the first and second images. The first and second images can then be registered in a single overlay and delineated such that any changes between corresponding segments can be highlighted on a display. The delineation may be displayed as an outline of the corresponding segments and may further indicate whether the change was an increase or decrease in an area of the brain over time (e.g., wherein an increase in area may be indicated by a solid line and a decrease may be indicated by a dotted line, wherein an increase in area may be indicated by a dotted line and a decrease may be indicated by a solid line, etc.). In some embodiments, the delineation may also display additional data including, but not limited to, area, circumference, volume, diameter (taken along one or both of a short and long axis), etc. of the highlighted portion. The exemplary system and method can enable a quick comparison of the structural differences between first and second images by providing an interactive visualization thereof. A user may toggle between each of the first, second and overlay images in turn to analyze any individual segments in greater detail and aid in making an analysis of a current state of the patient. 
     In accordance with an exemplary method according to the invention, a first data set (not shown) can be captured and stored in any storage medium along with detailed information including, but not limited to, patient information, time and data of data capture and any additional user notes. A second data set  100 , as shown in  FIG. 1 , can be captured after any of a lapse of a predetermined time period, administration of a treatment, occurrence of a major medical event (e.g., stroke, etc.), or any other time delay relative to capturing of the first data set. A brain segmentation tool can be used to segment multiple brain structures of interest  102 - 118  in each of the first data set (not shown) and the second data set  100 , as those skilled in the art will understand. Each of the structures  102 - 118  may be marked by colored contours having different colors or, in another embodiment, different line styles (e.g., dashes, varying thicknesses, etc.). The first data set may be segmented at the time of capture or, in another embodiment, may be segmented when the second data set is captured. 
       FIG. 2  depicts an exemplary overlay image  200 , which is a composite of first and second data sets corresponding to first and second brain scan images overlaid with one another. In an operative configuration, a user may select a comparison button to delineate all structural changes in the regions of interest  102 - 118  between the first and second data sets. Specifically, an exemplary procedure according to the invention is provided to overlay the first and second data sets in a manner such that corresponding structures  102 - 118  are aligned with one another, the procedure accounting for possible changes in anatomy between the first and second data sets. Specifically, a prerequisite for the visualization according to exemplary embodiments of the invention is the availability and co-registration of the structures  102 - 118  for each of the first and second data sets with either a rigid or deformable volume preserving constraint. This co-registration allows the segmented structures  102 - 118  of the first data set to appear at the correct position in the overlay image relative to their locations in the second data set. In the case of a bitmask-based segmentation, this can be achieved by co-registration of both the first and second data sets. The transformation between the first and second data sets is subsequently applied to the bitmask. In the case of a model-based segmentation, this may be achieved as described above with respect to the bitmask-based registration or, in another embodiment, by co-registration of meshes which represent the segmentation results. The resultant overlay image  200  displays delineated portions  107 ,  117  of the right and left hippocampus  106 ,  116 , respectively. Specifically, the dashed line for the delineated portions  107 ,  117  are indicative of a size and shape of the right and left hippocampus as taken from the first data set (not shown). The solid lines of the right and left hippocampus  106 ,  116  are indicative of a current size and shape thereof, as taken from the second data set  200 . In another exemplary embodiment, each of the left and right hippocampus  106 ,  116  and corresponding delineated portions  107 ,  117  may be marked with different contours including, but not limited to, different contour line colors, line thicknesses, line styles, etc. The image  200  provides a clear and easy to interpret visualization of any changes between the first and second data sets, thus eliminating a need for a user to toggle between multiple images to make a manual assertion of possible changes in any portion of the anatomy thereof. 
       FIG. 3  depicts an image  300  according to another exemplary embodiment of the invention. Specifically, a user may select any of the delineated portions  107 ,  117  by clicking on the corresponding structure on the image  200 . In the present embodiment, a user may select either of the structure  116  which corresponds to a left hippocampus of the brain or the delineated portion  117  thereof. This selection prompts the display of quantitative information  120  corresponding to changes in the left hippocampus between the first and second data sets. The quantitative information  120  includes, but is not limited to, volume, area, circumference and diameter (taken alone one or both of the short and long axes) of the structure in the first and second data sets or the delineated portion of the overlay image  300 . To improve clarity, the non-selected delineated portion  107  can be made invisible as long as the delineated portion  117  is being examined, as shown in  FIG. 3 . In another embodiment, as shown in  FIG. 4 , all non-selected structures  102 - 118  may also be made invisible so that only the selected delineated portion  117  is shown on an image  400 . The quantitative information  120  may be displayed as a sticky overlay to the image  300 ,  400  such that a user may scroll through the image  300 ,  400  or first and second data sets thereof while the quantitative information  120  stays visible in place. In another embodiment, the quantitative information  120  may display data corresponding to only the first data set when the first data set (not shown) is viewed and display data corresponding to only the second data set  100  when the second data set  100  is viewed. The quantitative information  120  may be displayed in a color corresponding to a color of the corresponding structure. The system and method according to exemplary embodiments of the invention can allow a user to toggle between any of the first data set, second data set and overlay image  200 ,  300 ,  400  with a single click, thus enabling a user to easily analyze quantitative information relating thereto. 
     It is noted that although images  100 ,  200 ,  300 ,  400  are shown with particular structures, any combination of displayed information may be used without deviating from the scope of the invention. In one example, when selecting a structure  102 - 118  for analysis, only adjacently positioned structures are removed from the display while outlying structures which, for example, do not overlap the selected structure, remain visible. In another example, when displaying a structure, both the structure and its corresponding delineated portion are displayed as a 3D contour intersecting a 2D image slice. In yet another example, a button may be provided to trigger the display of volumetric information for some or all structures. In another example, any plurality or all of the structures of the overlaid image may be displayed in both states at once (i.e., from first and second data sets). In still another embodiment, first and second data sets may be displayed side-by-side with their respective segmentations. In yet another embodiment, an overlay image may be formed as an overlay of three or more images to, for example, track a progression of an abnormality between three or more sessions. 
       FIGS. 5-6  depict an exemplary method  500  and system  600  according to exemplary embodiments of the invention. In a first step  502 , a first brain scan image (not shown) is captured and stored on a database  602  of a memory  604 . In step  504 , a second brain scan image  200  is captured and stored on the database  602 . As those skilled in the art may appreciate, the capturing steps  502 ,  504  may be optionally omitted. Rather, a processor  606  may reference first and second brain scan images previously stored on the database  602 . In step  506 , the processor  606  segments one or more brain structures of interest in each of the first and second brain scan images. In step  508 , the processor  606  generates the overlay image  300 ,  400  and displays the image  300 ,  400  on a display  608 . A radiologist or other user may manipulate, scroll through or otherwise edit any of the original first and second brain scans and overlay images  300 ,  400  via a user interface  610  which may include any of a keyboard, mouse and/or a touch display on the display  608 . 
     It will be appreciated by those skilled in the art that various modifications and alterations of the invention can be made without departing from the broad scope of the appended claims. Some of these have been discussed above and others will be apparent to those skilled in the art.