Abstract:
A system and method for organ image unfolding for feature visualization are provided, where the system includes a processor, an imaging adapter in signal communication with the processor for receiving organ scan data, a modeling unit in signal communication with the processor for fitting a model to the scan data, and an unfolding unit in signal communication with the processor for unfolding the 3D modeled scan data; and the corresponding method includes segmenting an outer surface of the organ, parameterizing a 3D model of the organ, ray-casting from the center of the organ to the surface of the 3D model, and unfolding the 3D model of the organ in correspondence with the ray-casting.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Application Ser. No. 60/492,394, filed Aug. 4, 2003 and entitled “Heart Unfolding for Coronary Visualization”, which is incorporated herein by reference in its entirety. 
    
    
     BACKGROUND 
     Medical image scanning data, for example, is typically obtained in the form of slices in various types of imaging modalities. These slices are then stacked to form a three-dimensional (“3D”) volume. This volume must then be visualized and segmented. 
     In current approaches to medical image scanning, researchers have developed a wide variety of segmentation techniques for isolating heart coronary arteries. Research in this field is motivated by the high number of patients suffering from coronary artery disease. Heart coronary arteries are typically difficult to segment because of their size and proximity to the surface of the heart and blood pool. 
     Accordingly, what is needed is a system and method capable of Heart Unfolding for Coronary Visualization. The present disclosure addresses these and other issues. 
     SUMMARY 
     These and other drawbacks and disadvantages of the prior art are addressed by an apparatus and method of heart unfolding for coronary visualization. 
     A system for organ image unfolding for feature visualization includes a processor, an imaging adapter in signal communication with the processor for receiving organ scan data, a modeling unit in signal communication with the processor for fitting a model to the scan data, and an unfolding unit in signal communication with the processor for unfolding the 3D modeled scan data. 
     A corresponding method for organ image unfolding for feature visualization includes segmenting an outer surface of the organ, parameterizing a 3D model of the organ, ray-casting from the center of the organ to the surface of the 3D model, and unfolding the 3D model of the organ in correspondence with the ray-casting. 
     These and other aspects, features and advantages of the present disclosure will become apparent from the following description of exemplary embodiments, which is to be read in connection with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present disclosure teaches an apparatus and method of Heart Unfolding for Coronary Visualization, in accordance with the following exemplary figures, in which: 
         FIG. 1  shows an apparatus for Heart Unfolding for Coronary Visualization in accordance with an illustrative embodiment of the present disclosure; 
         FIG. 2  shows a flowchart for Heart Unfolding for Coronary Visualization in accordance with an illustrative embodiment of the present disclosure; 
         FIG. 3  shows a 3D MIP texture on an isosurface volume in accordance with an illustrative embodiment of the present disclosure; 
         FIG. 4  shows an unfolding visualization in accordance with an illustrative embodiment of the present disclosure; 
         FIG. 5  shows a VRT visualization in accordance with an illustrative embodiment of the present disclosure; 
         FIG. 6  shows an MIP visualization in accordance with an illustrative embodiment of the present disclosure; 
         FIG. 7  shows a 3D model visualization in accordance with an illustrative embodiment of the present disclosure; 
         FIG. 8  shows another 3D model visualization in accordance with an illustrative embodiment of the present disclosure; and 
         FIG. 9  shows yet another 3D model visualization in accordance with an illustrative embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     In accordance with preferred embodiments of the present disclosure, a system and method of Heart Unfolding for Coronary Visualization are described herein. The method allows a user to better visualize the heart coronaries and vessels on the surface of the heart. 
     In recent decades, researchers have developed a wide variety of segmentation techniques for isolating heart coronary arteries. Research in this field is motivated by the high number of patients suffering from coronary artery disease. Heart coronary arteries are typically difficult to segment because of their size and proximity to the surface of the heart and blood pool. 
     Because of the difficulty with segmentation, and because of the proximity of coronary arteries to the surface of the heart, a surface unfolding approach can be used to overcome the visualization problem to some degree. This technique provides a great improvement for visualization of the heart coronary arteries. 
     The presently disclosed method incudes “unfolding” the surface of the heart and creating a Maximum Intensity Projection (MIP) of this surface. The result is a 2D map of the surface of the heart, containing the peripheral vessels. 
     As shown in  FIG. 1 , a system for acquisition-time modeling and automated post-processing according to an illustrative embodiment of the present disclosure is indicated generally by the reference numeral  100 . The system  100  includes at least one processor or central processing unit (“CPU”)  102  in signal communication with a system bus  104 . A read only memory (“ROM”)  106 , a random access memory (“RAM”)  108 , a display adapter  110 , an I/O adapter  112 , a user interface adapter  114 , a communications adapter  128 , and an imaging adapter  130  are also in signal communication with the system bus  104 . A display unit  116  is in signal communication with the system bus  104  via the display adapter  110 . A disk storage unit  118 , such as, for example, a magnetic or optical disk storage unit is in signal communication with the system bus  104  via the I/O adapter  112 . A mouse  120 , a keyboard  122 , and an eye tracking device  124  are in signal communication with the system bus  104  via the user interface adapter  114 . A magnetic resonance imaging device  132  is in signal communication with the system bus  104  via the imaging adapter  130 . 
     A modeling unit  170  and an unfolding unit  180  are also included in the system  100  and in signal communication with the CPU  102  and the system bus  104 . While the modeling unit  170  and the unfolding unit  180  are illustrated as coupled to the at least one processor or CPU  102 , these components are preferably embodied in computer program code stored in at least one of the memories  106 ,  108  and  118 , wherein the computer program code is executed by the CPU  102 . As will be recognized by those of ordinary skill in the pertinent art based on the teachings herein, alternate embodiments are possible, such as, for example, embodying some or all of the computer program code in registers located on the processor chip  102 . Given the teachings of the disclosure provided herein, those of ordinary skill in the pertinent art will contemplate various alternate configurations and implementations of the modeling unit  170  and the unfolding unit  180 , as well as the other elements of the system  100 , while practicing within the scope and spirit of the present disclosure. 
     Turning to  FIG. 2 , a flowchart for acquisition Heart Unfolding for Coronary Visualization according to an illustrative embodiment of the present disclosure is indicated generally by the reference numeral  200 . The flowchart  200  includes a start block  210  that passes control to a function block  212 . The function block  212  initiates a preliminary heart scanning session and passes control to an input block  214 . The input block  214  receives preliminary heart scan data and passes control to a function block  216 . 
     The function block  216  segments the heart&#39;s outer surface and passes control to a function block  218 . The function block  218  performs a fixed 3D model parameterization of the heart and passes control to a function block  220 . The function block  220  casts rays from the center of the heart to the surface of the 3D model, and passes control to a function block  222 . The function block  222  unfolds the 3D model and passes control to an end block  224 . 
     Turning now to  FIG. 3 , a 3D MIP texture on an isosurface volume is indicated generally by the reference numeral  300 . The 3D MIP texture  300  provides a visualization for heart unfolding. 
     As shown in  FIG. 4 , a heart unfolding visualization is indicated generally by the reference numeral  400 . Unfolding the surface of the heart brings a new way to visualize the coronaries. The unfolding visualization  400  shows the correlation between an MIP  410  (above) and an unfolded heart surface  420  (below). 
     Turning to  FIG. 5 , a common VRT visualization is indicated generally by the reference numeral  500 . In this exemplary embodiment, a graph cut algorithm is used to get a hollow heart volume that will determine the surface to be unfolded. The VRT visualization  500  is shaded by a 3D Syngo card in this example. 
     Turning now to  FIG. 6 , common MIP visualization is indicated generally by the reference numeral  600 . Here, the regular MIP view shows that the coronaries are obstructed by bright tissues. The MIP visualization  600  of the thick surface is shown by a 3D Syngo card in this example. 
     As shown in  FIG. 7 , a new 3D model visualization is indicated generally by the reference numeral  700 . The new 3D model visualization  700  shows a 3D MIP texture mapped on an isosurface volume. 
     Turning to  FIG. 8 , another new 3D model visualization is indicated generally by the reference numeral  800 . Here, The new 3D model visualization  800  shows fitting an ellipsoid  810  to the surface of the heart  820 , projecting an MIP texture on the ellipsoid  810 , visualization of the 3D model, and fitting the ellipsoid  810  (left) or a sphere  830  (right) to the surface of the heart  820 . 
     Turning now to  FIG. 9 , a 3D model visualization is indicated generally by the reference numeral  900 . The 3D model visualization  900  indicates actual results of an exemplary embodiment heart unfolding method as applied to real data. As will be recognized by those of ordinary skill in the pertinent art, such results have a greater clinical value than was achievable with prior methods. 
     This exemplary method brings an improved visualization technique for the heart coronaries, as well as vessels on the surface of the heart. The basic principle is to “unfold” the surface of the heart and create a MIP of this unfolded surface. The resulting 2D map of the surface of the heart contains highly contrasted vessels. 
     Thus, the exemplary technique used for unfolding the surface of the heart is accomplished in four steps: 1) Segmentation of the heart&#39;s outer surface; 2) Fixed 3D Model parameterization of the heart; 3) Casting rays from the center of the heart to the surface of the 3D model (MIP filter can be applied here); and 4) Unfolding of the 3D Model. 
     A graph cut algorithm as known in the art, for example, may be used to segment the outer surface of the heart. From the result of this segmentation, a distance map is created to evaluate the distance from each point on the volume to the segmented surface of the heart. Then, a known 3D model can be fit into the heart so that the surface of the heart fits the surface of the model. After this step, a ray is cast from the center of the heart to the surface of the 3D model. A profile curve is created while the ray propagates through the heart, and a response filter is applied to detect the eventual location of a vessel. If a location is found, then the algorithm displays the result on the surface of the 3D Model. As will be recognized by those of ordinary skill in the pertinent art, the unfolding of the 3D model is a widely-studied problem and several different algorithms can be used. 
     A preferred embodiment uses a sphere as 3D model and Maximum Intensity Projection (MIP) as the profile curve filter. Although alternate 3D models and ray filters may be used, some may adversely impact the quality of the results. 
     Thus, preferred embodiments of the present disclosure provide powerful heart unfolding tools for coronary visualization, enabling users to extract significant features and regions-of-interest. Preferred embodiments can serve as very useful acquisition-time modeling and automated post-processing tools in clinical applications. 
     These and other features and advantages of the present disclosure may be readily ascertained by one of ordinary skill in the pertinent art based on the teachings herein. It is to be understood that the teachings of the present disclosure may be implemented in various forms of hardware, software, firmware, special purpose processors, or combinations thereof. 
     Most preferably, the teachings of the present disclosure are implemented as a combination of hardware and software. Moreover, the software is preferably implemented as an application program tangibly embodied on a program storage unit. The application program may be uploaded to, and executed by, a machine comprising any suitable architecture. Preferably, the machine is implemented on a computer platform having hardware such as one or more central processing units (“CPU”), a random access memory (“RAM”), and input/output (“I/O”) interfaces. The computer platform may also include an operating system and microinstruction code. The various processes and functions described herein may be either part of the microinstruction code or part of the application program, or any combination thereof, which may be executed by a CPU. In addition, various other peripheral units may be connected to the computer platform such as an additional data storage unit and a printing unit. 
     It is to be further understood that, because some of the constituent system components and methods depicted in the accompanying drawings are preferably implemented in software, the actual connections between the system components or the process function blocks may differ depending upon the manner in which the present disclosure is programmed. Given the teachings herein, one of ordinary skill in the pertinent art will be able to contemplate these and similar implementations or configurations of the present disclosure. 
     Although the illustrative embodiments have been described herein with reference to the accompanying drawings, it is to be understood that the present disclosure is not limited to those precise embodiments, and that various changes and modifications may be effected therein by one of ordinary skill in the pertinent art without departing from the scope or spirit of the present disclosure. All such changes and modifications are intended to be included within the scope of the present disclosure as set forth in the appended claims.