Abstract:
A method for graphic visualization of ventricle wall motion includes acquiring medical imaging data frames depicting at least one cardiac cycle, identifying a ventricle wall outline in at least a portion of the plurality of image frames, determining end systolic and end diastolic frames belonging to a same cardiac cycle, copying the ventricle wall outline image from the ES and the ED frames, creating a composite image frame that includes the copied ventricle wall outline images, assigning a first color to the ES and a second color to the ED outline images of the composite frame, and providing the composite frame for displaying, printing, and/or storing in memory. A system for implementing the method and a non-transitory computer-readable medium are also disclosed.

Description:
BACKGROUND 
     Digital medical images of a heart are acquired and analyzed to perform cardiac ventricle analysis. Each of these images can be a collection of frames which show the heart as it beats. As the heart transitions from systolic phase to diastolic phase, there is a visible change to the ventricle wall in each frame. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  depicts a system in accordance with some embodiments; 
         FIG. 2  depicts an imaging data unit in accordance with the system depicted in  FIG. 1 ; 
         FIGS. 3A-3D  depict ventricle wall outline image frame grabs in accordance with some embodiments; 
         FIG. 4  depicts a superimposed composite image in accordance with some embodiments; 
         FIG. 5  depicts another superimposed composite image in accordance with some embodiments; and 
         FIGS. 6A-6B  depicts a process in accordance with some embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     In accordance with embodiments, graphic visualization of the motion of a ventricle wall is provided by introducing a changing color in a collection of outlines of the ventricle wall in each frame of a multi-frame image as the heart transitions between systolic and diastolic phases. In accordance with some implementations, the End Diastolic (ED) frame and the End Systolic (ES) frame for a particular cardiac cycle can be identified from a series of frames obtained by a medical imaging system. The ventricle wall outline can be identified in image frames of the cardiac cycle, and a composite frame of the series of images can be formed. By introducing a graphic visualization into the composite frame, the ventricle wall motion for a single heart beat (i.e., from ES to ED frame) can be displayed. 
       FIG. 1  depicts system  10  for providing a composite, graphically-enhanced image of ventricle wall motion in accordance with some embodiments. This composite graphically-enhanced image can be displayed on monitor  33 , printed, and/or stored in memory store  40  for later access. 
     System  10  employs at least one processing device  30  for processing images acquired by imaging system  25  for display on monitor  33 . Specifically, processing device  30  comprises at least one computer, server, microprocessor, programmed logic device, ASIC, FPGA, or other processing device comprising repository  17 , image data processor  15 , output processor  20  and acquisition processor  12 . Acquisition processor  12  acquires medical images from imaging system  25 . Imaging system  25  can be a medical imaging system of any type or nature—such as an MR, X-ray, CT scan or ultrasound imaging system. 
       FIG. 2  depicts an imaging data unit  200  in accordance with some embodiments. The imaging data unit can include image data processor  15 , vision unit  50 , and frame grabber unit  60 . Vision unit  50  is structured to identify the ventricle wall outline of a heart in the frames of the acquired medical images. In accordance with implementations, these frames can be consecutive frames, sequentially sampled (ordered but not consecutive) or not ordered at all. The vision unit can identify which are the ED frame and the ES frame, and those intermediary frames which occur between the ED and ES frames. In accordance with some implementations, the ED and ES frames can be identified by correlating the image frame with an ECG waveform taken simultaneously with the imaging data. In other implementations, the frames can be manually identified. 
     Frame grabber unit  60  is structured to isolate and copy at least a portion of the image from each frame identified by the vision unit. In particular, the frame grabber unit isolates and copies the outline of the ventricle wall perimeter from the frames of the same cardiac cycle that includes the identified ES and ED frames. In some implementations, the ventricle wall perimeter can be manually identified by a user marking the heart&#39;s apex and two points of the aorta. The isolated ventricle wall outlines can be superimposed together to create a composite frame that includes the removed ventricle wall perimeters. This superimposed composite frame can visualize the motion of the ventricle wall in one image. In accordance with some embodiments, this superimposed composite frame can include graphical visualization that indicates the movement of the ventricle wall as the wall transitions between the systolic and diastolic phases. With reference to  FIG. 1 , output processor  20  outputs the composite image for display on monitor  33 , and/or storage into memory store  40 . 
       FIG. 3A  depicts a ventricle wall outline image frame grab  300  for an ED frame. Similarly,  FIG. 3D  depicts a ventricle wall outline image frame grab  330  for an ES frame.  FIGS. 3B and 3C  depict ventricle outline image frame grabs  310 ,  320  for frames between the ED and ES frames. Each of the frames depicted in  FIGS. 3A-3D  can be identified by vision unit  50  and isolated by frame grabber unit  60  in accordance with some embodiments. 
       FIG. 4  depicts superimposed composite image  400  in accordance with some embodiments. For purposes of discussion only two frames ( FIGS. 3B and 3C ) are depicted between the ES and ED frames. However as will be readily understood, there could be more or less frames presented in the composite image. Between each ventricle outline image  300 ,  310 ,  320 ,  330  there are inter-outline regions  410 ,  415 ,  420 . Additionally, ventricle outline image  300  circumscribes intra-outline region  405 . 
     With reference to  FIG. 2 , image data unit  200  can include graphic visualization unit  70  in accordance with some embodiments. Graphic visualization unit  70  provides graphic visualization features to the composite image. In accordance with implementations, an interactive user interface can be presented on monitor  33 . A user can interact with the user interface to select at least a starting graphic feature for the ED frame and an ending graphic feature for the ES frame. Selection of intermediate graphic features for intervening frames of the superimposed composite image can also be selected by the user. In accordance with some embodiments, graphic visualization unit  70  provides the intermediate graphic features based on the ED and ES graphic features. In some implementations, the ED and ES graphic features themselves can be selected by the graphic visualization unit without receiving a selection from the user. 
     In accordance with some embodiments, graphic visualization unit  70  can assign a first color for the ED ventricle outline image frame grab and a second color for the ES ventricle outline image frame grab. The assigned colors can be based on user input in accordance with some implementations. A first color for the ED ventricle outline image can be expressed as RGB=(R 1 , G 1 , B 1 ), and a second color for the ES ventricle outline image can be expressed as RGB=(RN, GN, BN), where there are N ventricle outline images of the cardiac cycle depicted in the superimposed composite image frame ( FIG. 4 ). The intermediary ventricle wall outline images can have colors assigned that interpolate along the color spectrum based on the position of the intermediary ventricle wall outline image&#39;s position in the composite image. In accordance with some embodiments, for any ventricle outline image X, the RGB color of a ventricle outline X can be expressed by Equation 1:
 
 RGB ( X )=((( N−X )* R 1+( X− 1)* RN )/( N− 1),(( N−X )* G 1+( X− 1)* GN )/( N− 1),(( N−X )* B 1+( X− 1)* BN )/( N− 1))  (EQ. 1)
 
     where N=the number of ventricle outline images; and
         X=the ventricle outline image number.       

     By way of example, suppose for ED ventricle wall outline image  300  an eight bit RGB=(R 1 ,G 1 ,B 1 ) of red is assigned. Also, suppose for ES ventricle wall outline image  330  an eight bit RGB=(R 4 ,G 4 ,B 4 ) of blue is assigned. Then in accordance with an implementation, the ventricle wall outline images can be colored as follows: 
     ED ventricle wall outline image  300 : RGB(255,0,0); 
     Intermediary ventricle wall outline image  310 : RGB(*255/3,0,255/3) or RGB(170,0,85); 
     Intermediary ventricle wall outline image  320 : RGB(255/3,0, 2*255/3) or RGB(85,0,170); and 
     ED ventricle wall outline image  330 : RGB(0,0,255). 
     The variation in color of the ventricle wall outline images is depicted in  FIG. 4  as varying shades of gray, where ED ventricle wall outline  300  is the darkest and ES ventricle wall outline  330  is the lightest. 
     In accordance with some embodiments, pixels in inter-outline regions  410 ,  415 ,  420  can also be presented in color. Additionally, intra-region  405  can also be presented in color. In accordance with some implementations, the color assigned to these inter-outline regions can be progressively shaded based on an interpolation between the ventricle wall outline images that circumscribe the inter-outline region. This interpolation can account for the positioning of a pixel within the inter-outline image in relation to its distance from each of the circumscribing ventricle wall outline images. Based on the pixel positioning, a color can be assigned. 
     By way of example, suppose ventricle wall outline image X is assigned RGB=(RX,GX,BX) and adjacent ventricle wall outline image X+1 is assigned RGB=(RY,BY,BY). Further, a pixel in the inter-outline region has a first distance DX from outline image X, and a second distance DY from outline image X+1. In accordance with some embodiments, this pixel would be assigned a color expressed by Equation 2:
 
 RGB= ( DY*RX+DX*RY )/( DX+DY ),( DY*GX+DX*GY )/( DX+DY ),( DY*BX+DX*BY )/( DX+DY )  (EQ. 2)
 
     If a pixel located in inter-outline region  415  is six pixels from ventricle wall outline image  320  and is nine pixels from ventricle wall outline image  310 , then the assigned color for this pixel can be expressed as:
 
 RGB= (9*170+6*85)/(6+9),(9*0+6*0)/(6+9),(9*85+6*170)/(6+9)
 
or
 
 RGB= (136,0,119)
 
     where DY=9; DX=6; RX=170; GX=0; BX=85; RY=85; GY=0; and BY=170. 
     In accordance with some embodiments, special cases of a point lying between more than one pair of adjacent contours can be addressed during the interpolation. For example, if the ED outline image and the ES outline image are misidentified. If a cardiac cycle includes the four outline images depicted in  FIG. 3 , but ventricle wall outline image  320  and ventricle wall outline image  330  are interchanged. Naturally, it is well understood that the smallest ventricle volume is the ES frame. However with this interchange of outline images, there can be some points between ventricle wall outline image  310  and ventricle wall outline image  320  that can also be between the interchanged outline images. In such a case where some pixels are located between two pairs of adjacent ventricle wall outlines, these pixels can be assigned two colors by graphic visualization unit  70 . 
     Also, one or more pixels can be assigned multiple colors if the cardiac wall is misidentified by vision unit  50 , or if there is some actual irregular movement in the cardiac wall in one or more of the grabbed frame images.  FIG. 5  depicts superimposed composite image  500  in accordance with some embodiments. The cardiac cycle depicted in composite image  500  includes ventricle wall outline images  300 ,  310 ,  320  plus ventricle wall outline image  530 . Due to the perturbation in ventricle wall outline image  530 , a portion  540  of the wall outline will cross through outline  320 , and there will be some pixels in the inter-outline region that will be between ventricle wall outline images  320 ,  530  and ventricle wall outline image  310 ,  530 . 
     In accordance with some implementations, this special case can be addressed with one of three options. First, the color assignment can be given based on the earliest time in the cardiac cycle. Second, the color can be assigned based on the latest time in the cardiac cycle. Third, a different color can be assigned to highlight the pixels of the crossover region. 
       FIGS. 6A-6B  depicts process  600  for providing graphic visualization of ventricle wall motion in medical imaging frames in accordance with some embodiments. Medical imaging data frames depicting at least one cardiac cycle are acquired, step  605 , from a medical imaging system. The vision unit of an image data unit identifies, step  610 , a ventricle wall outline in at least a portion of the acquired images frames. An ES frame and an ED frame are determined, step  615 , from the identified ventricle wall outline images. Intermediary frames occurring in the same cardiac cycle defined by the ES and ED frames are located, step  620 . The ventricle wall outlines from the ES, ED and intermediary frames are copied by a frame grabber unit, step  625 . The frame grabber unit creates, step  630 , a composite image frame that is a superposition of the copied ventricle wall outline images. A first color and a second color are respectively assigned, step  635 , to the ES and ED ventricle wall outlines. Respective colors are assigned, step  640 , to each of the intermediary ventricle outlines of the composite image. The composite frame is provided, step  645 , for display, printing, and/or storage in memory. 
     In accordance with some embodiments, a computer program application stored in non-volatile memory or computer-readable medium (e.g., register memory, processor cache, RAM, ROM, hard drive, flash memory, CD ROM, magnetic media, etc.) may include code or executable instructions that when executed may instruct and/or cause a controller or processor to perform methods discussed herein such as a method providing graphic visualization of ventricle wall motion, as described above. 
     The computer-readable medium may be a non-transitory computer-readable media including all forms and types of memory and all computer-readable media except for a transitory, propagating signal. In one implementation, the non-volatile memory or computer-readable medium may be external memory. 
     Although specific hardware and methods have been described herein, note that any number of other configurations may be provided in accordance with embodiments of the invention. Thus, while there have been shown, described, and pointed out fundamental novel features of the invention, it will be understood that various omissions, substitutions, and changes in the form and details of the illustrated embodiments, and in their operation, may be made by those skilled in the art without departing from the spirit and scope of the invention. Substitutions of elements from one embodiment to another are also fully intended and contemplated. The invention is defined solely with regard to the claims appended hereto, and equivalents of the recitations therein.