Patent Publication Number: US-2010125203-A1

Title: Finding A Standard View Corresponding To An Acquired Ultrasound Image

Description:
The present application claims priority from Korean Patent Application No. 10-2008-0115316 filed on Nov. 19, 2008, the entire subject matter of which is incorporated herein by reference. 
     TECHNICAL FIELD 
     The present disclosure generally relates to ultrasound systems, and more particularly to an ultrasound system and method of automatically finding a standard view corresponding to an acquired ultrasound image. 
     BACKGROUND 
     An ultrasound system has become an important and popular diagnostic tool since it has a wide range of applications. Specifically, due to its non-invasive and non-destructive nature, the ultrasound system has been extensively used in the medical profession. Modern high-performance ultrasound systems and techniques are commonly used to produce two or three-dimensional diagnostic images of internal features of an object (e.g., human organs). 
     The plane images provided by the ultrasound system may be generally classified into various types of standard views, such as a parasternal view, an apical view, a subcostal view, a suprasternal view, etc. may be acquired in the ultrasound system. Conventionally, the view type of the heart is manually selected by the user. Thus, the user may commit an error in selecting a standard view for desirable observation, so that the ultrasound image may not be adequately observed. 
     SUMMARY 
     Embodiments for testing an acoustic property of an ultrasound probe including a plurality of transducer elements are disclosed herein. In one embodiment, by way of non-limiting example, an ultrasound system comprises: a storage unit to store a mapping table associating information on a plurality of standard views of a target object with predetermined first feature vectors; an ultrasound data acquisition unit operable to transmit ultrasound signals to the target object and receive echo signals reflected from the target object, the ultrasound data acquisition unit being further operable to form ultrasound data based on the receive echo signals; an ultrasound image forming unit operable to form an ultrasound image based on the ultrasound data; and a processing unit operable to calculate a second feature vector from the ultrasound image and refer to the mapping table to select one of the predetermined first feature vectors closest to the second feature vector, the processing unit being further operable to extract information on the standard view corresponding to the selected predetermined first feature vector from the mapping table. 
     In another embodiment, a method of providing information on one of a plurality of standard views of a target object in an ultrasound system, comprises: a) storing a mapping table associating information on a plurality of standard views of a target object with predetermined first feature vectors; b) transmitting ultrasound signals to the target object and receive echo signals reflected from the target object to form ultrasound data based on the receive echo signals; c) forming an ultrasound image based on the ultrasound data; d) calculating a second feature vector from the ultrasound image; and e) referring to the mapping table to select one of the first feature vectors closest to the second feature vector to extract information on the standard view corresponding to the selected predetermined first feature vector from the mapping table. 
     The Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used in determining the scope of the claimed subject matter. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram showing an illustrative embodiment of an ultrasound system. 
         FIG. 2  is a block diagram showing an illustrative embodiment of an ultrasound data acquisition unit. 
         FIG. 3  is a flowchart showing a procedure of forming a mapping table associating information on standard views of a target object with predetermined feature vectors. 
         FIG. 4  is a schematic diagram showing examples of typical plane images corresponding to standard views. 
         FIG. 5  is a block diagram showing an illustrative embodiment of a processing unit. 
         FIG. 6  is a schematic diagram showing an example of an ultrasound image. 
     
    
    
     DETAILED DESCRIPTION 
     A detailed description may be provided with reference to the accompanying drawings. One of ordinary skill in the art may realize that the following description is illustrative only and is not in any way limiting. Other embodiments of the present invention may readily suggest themselves to such skilled persons having the benefit of this disclosure. 
       FIG. 1  is a block diagram showing an illustrative embodiment of an ultrasound system. As depicted therein, the ultrasound system  100  may include a storage unit  110  that may store a mapping table associating information upon a plurality of standard views of a target object with first feature vectors, which were previously calculated from typical plane images corresponding to the respective standard views. The detailed description of calculating the first feature vectors from the plane images will be described later. In one embodiment, the target object may include a heart, and the standard views may include a parasternal view, an apical view, a subcostal view, a suprasternal view, etc. 
     The ultrasound system  100  may further include an ultrasound data acquisition unit  120 . The ultrasound data acquisition unit  120  may be operable to transmit/receive ultrasound signals to/from the target object to thereby form ultrasound data. 
     Referring to  FIG. 2 , the ultrasound data acquisition unit  120  may include a transmit (Tx) signal generator  121  that may be operable to generate a plurality of Tx signals. The ultrasound data acquisition unit  120  may further include an ultrasound probe  122  coupled to the Tx signal generator  121 . The ultrasound probe  122  may be operable to transmit the ultrasound signals to the target object in response to the Tx signals. The ultrasound probe  122  may be further operable to receive echo signals reflected from the target object to thereby form electrical receive signals. The ultrasound probe  122  may contain an array transducer consisting of a plurality of transducer elements. The array transducer may include a 1D or 2D array transducer, but is not limited thereto. The array transducer may be operable to generate ultrasound signals and convert the echo signals into the electrical receive signals. 
     The ultrasound data acquisition unit  120  may further include a beam former  123 . The beam former  123  may be operable to apply delays to the electrical receive signals in consideration of positions of the transducer elements and focal points. The beam former  123  may further be operable to sum the delayed receive signals to thereby output a plurality of receive-focused beams. The ultrasound data acquisition unit  120  may further include an ultrasound data forming section  124  that may be operable to form the ultrasound data based on the receive-focused beams. In one embodiment, the ultrasound data may be radio frequency data or in-phase/quadrature data. 
     Referring back to  FIG. 1 , the ultrasound system  100  may further include an ultrasound image forming unit  130 . The ultrasound image forming unit  130  may be operable to form an ultrasound image based on the ultrasound data formed in the ultrasound data acquisition unit  110 . In one embodiment, by way of non-limiting example, the ultrasound image may be a brightness mode image. The ultrasound image may be also stored in the storage unit  110 . 
     The ultrasound system  100  may further include a processing unit  140 . The processing unit  140  may be operable to calculate a second feature vector from the ultrasound image formed in the ultrasound image forming unit  130 . The processing unit  140  may be further operable to compute an Euclidean distance between the second feature vector and each of the first feature vectors of the mapping table stored in the storage unit  110 . The processing unit  140  may be further operable to select one of the first feature vectors, which has the closest Euclidean distance, and access the storage unit  110  to find one of the standard views corresponding to the selected first feature vector from the mapping table. The information found may be displayed on a screen of a display unit  150 . 
     Hereinafter, the detailed description of calculating the first feature vectors from the typical plane images corresponding to the respective standard views will follow with reference to  FIG. 3 . In one embodiment, by way of non-limiting example, the feature vectors may be calculated by using statistical algorithm, such as principle component analysis, etc. 
       FIG. 3  is a flowchart showing a procedure of forming a mapping table associating information on the standard views of a target object with the first feature vectors calculated from the typical plane images corresponding to the standard views. As illustrated in  FIG. 3 , initial vectors may be established from the plurality of plane images corresponding to the respective standard views of the target object at S 310 . In one embodiment, the initial vectors may be established by transforming pixel values of each plane image into a 1-dimensional matrix (i.e., 1×N), wherein N is the number of the pixels. For example, assuming that four plane images  211 - 214  corresponding to the parasternal view, apical view, subcostal view and suprasternal view are provided, as shown in  FIG. 4 , four initial vectors x 1 -x 4  corresponding to the respective plane images  211 - 214  may be established by sequentially taking the pixel values in each of the plane images  211 - 214  in a horizontal direction to form a column vector, as follows: 
     
       
         
           
             
               
                 
                   
                     x 
                     1 
                   
                   = 
                   
                     
                       
                         [ 
                         
                           
                             
                               225 
                             
                           
                           
                             
                               229 
                             
                           
                           
                             
                               48 
                             
                           
                           
                             
                               251 
                             
                           
                           
                             
                               33 
                             
                           
                           
                             
                               238 
                             
                           
                           
                             
                               0 
                             
                           
                           
                             
                               255 
                             
                           
                           
                             
                               217 
                             
                           
                         
                         ] 
                       
                        
                       
                           
                       
                        
                       
                         x 
                         2 
                       
                     
                     = 
                     
                       
                         
                           [ 
                           
                             
                               
                                 10 
                               
                             
                             
                               
                                 219 
                               
                             
                             
                               
                                 24 
                               
                             
                             
                               
                                 255 
                               
                             
                             
                               
                                 18 
                               
                             
                             
                               
                                 247 
                               
                             
                             
                               
                                 17 
                               
                             
                             
                               
                                 255 
                               
                             
                             
                               
                                 2 
                               
                             
                           
                           ] 
                         
                          
                         
                             
                         
                          
                         
                           x 
                           3 
                         
                       
                       = 
                       
                         
                           
                             [ 
                             
                               
                                 
                                   196 
                                 
                               
                               
                                 
                                   35 
                                 
                               
                               
                                 
                                   234 
                                 
                               
                               
                                 
                                   232 
                                 
                               
                               
                                 
                                   59 
                                 
                               
                               
                                 
                                   244 
                                 
                               
                               
                                 
                                   243 
                                 
                               
                               
                                 
                                   57 
                                 
                               
                               
                                 
                                   226 
                                 
                               
                             
                             ] 
                           
                            
                           
                               
                           
                            
                           
                             x 
                             4 
                           
                         
                         = 
                         
                           [ 
                           
                             
                               
                                 225 
                               
                             
                             
                               
                                 223 
                               
                             
                             
                               
                                 224 
                               
                             
                             
                               
                                 255 
                               
                             
                             
                               
                                 0 
                               
                             
                             
                               
                                 255 
                               
                             
                             
                               
                                 249 
                               
                             
                             
                               
                                 255 
                               
                             
                             
                               
                                 235 
                               
                             
                           
                           ] 
                         
                       
                     
                   
                 
               
               
                 
                   ( 
                   1 
                   ) 
                 
               
             
           
         
       
     
     Thereafter, a mean vector of the initial vectors x 1 -x 4  may be calculated at S 320 , and then the mean vector may be stored in the storage unit  110 . The mean vector may be calculated through the following equation. 
     
       
         
           
             
               
                 
                   m 
                   = 
                   
                     
                       1 
                       P 
                     
                      
                     
                       
                         ∑ 
                         
                           i 
                           = 
                           1 
                         
                         P 
                       
                        
                       
                         x 
                         i 
                       
                     
                   
                 
               
               
                 
                   ( 
                   2 
                   ) 
                 
               
             
           
         
       
         
         where m represent the mean vector, and P represents the number of the initial vectors x 1 -x 4 . For example, when the equation (2) is applied to the initial vectors x 1 -x 4 , the following mean vector may be obtained. 
       
    
     
       
         
           
             
               
                 
                   m 
                   = 
                   
                     [ 
                     
                       
                         
                           171.50 
                         
                       
                       
                         
                           176.50 
                         
                       
                       
                         
                           135.5 
                         
                       
                       
                         
                           248.25 
                         
                       
                       
                         
                           27.50 
                         
                       
                       
                         
                           246.00 
                         
                       
                       
                         
                           127.25 
                         
                       
                       
                         
                           205.50 
                         
                       
                       
                         
                           170.00 
                         
                       
                     
                     ] 
                   
                 
               
               
                 
                   ( 
                   3 
                   ) 
                 
               
             
           
         
       
     
     Subsequently, the mean vector m may be subtracted from each of the initial vectors x 1 -x 4  to thereby obtain intermediate vectors  x 1   -  x 4   . The intermediate vectors  x 1   -  x 4    may be represented as follows: 
     
       
         
           
             
               
                 
                   
                     
                       x 
                       1 
                     
                     _ 
                   
                   = 
                   
                     
                       
                         [ 
                         
                           
                             
                               53.50 
                             
                           
                           
                             
                               52.50 
                             
                           
                           
                             
                               
                                 - 
                                 84.50 
                               
                             
                           
                           
                             
                               2.75 
                             
                           
                           
                             
                               5.50 
                             
                           
                           
                             
                               
                                 - 
                                 8.00 
                               
                             
                           
                           
                             
                               
                                 - 
                                 127.25 
                               
                             
                           
                           
                             
                               49.50 
                             
                           
                           
                             
                               47.00 
                             
                           
                         
                         ] 
                       
                        
                       
                           
                       
                        
                       
                         
                           x 
                           2 
                         
                         _ 
                       
                     
                     = 
                     
                       
                         
                           [ 
                           
                             
                               
                                 
                                   - 
                                   161.50 
                                 
                               
                             
                             
                               
                                 42.50 
                               
                             
                             
                               
                                 
                                   - 
                                   108.50 
                                 
                               
                             
                             
                               
                                 6.75 
                               
                             
                             
                               
                                 
                                   - 
                                   9.50 
                                 
                               
                             
                             
                               
                                 1.00 
                               
                             
                             
                               
                                 
                                   - 
                                   110.25 
                                 
                               
                             
                             
                               
                                 49.50 
                               
                             
                             
                               
                                 
                                   - 
                                   168.00 
                                 
                               
                             
                           
                           ] 
                         
                          
                         
                             
                         
                          
                         
                           
                             x 
                             3 
                           
                           _ 
                         
                       
                       = 
                       
                         
                           
                             [ 
                             
                               
                                 
                                   24.50 
                                 
                               
                               
                                 
                                   
                                     - 
                                     141.50 
                                   
                                 
                               
                               
                                 
                                   101.50 
                                 
                               
                               
                                 
                                   
                                     - 
                                     16.25 
                                   
                                 
                               
                               
                                 
                                   31.50 
                                 
                               
                               
                                 
                                   
                                     - 
                                     2.00 
                                   
                                 
                               
                               
                                 
                                   115.75 
                                 
                               
                               
                                 
                                   
                                     - 
                                     148.50 
                                   
                                 
                               
                               
                                 
                                   56.00 
                                 
                               
                             
                             ] 
                           
                            
                           
                               
                           
                            
                           
                             
                               x 
                               4 
                             
                             _ 
                           
                         
                         = 
                         
                           [ 
                           
                             
                               
                                 83.50 
                               
                             
                             
                               
                                 46.50 
                               
                             
                             
                               
                                 91.50 
                               
                             
                             
                               
                                 6.75 
                               
                             
                             
                               
                                 
                                   - 
                                   27.50 
                                 
                               
                             
                             
                               
                                 9.00 
                               
                             
                             
                               
                                 121.75 
                               
                             
                             
                               
                                 49.50 
                               
                             
                             
                               
                                 65.00 
                               
                             
                           
                           ] 
                         
                       
                     
                   
                 
               
               
                 
                   ( 
                   4 
                   ) 
                 
               
             
           
         
       
     
     An intermediate matrix  X  may be obtained by using the intermediate vectors  x 1   -  x 4    at S 340 . The intermediate matrix  X  may be expressed as follows: 
     
       
         
           
             
               
                 
                   
                     X 
                     _ 
                   
                   = 
                   
                     [ 
                     
                       
                         
                           53.50 
                         
                         
                           
                             - 
                             161.50 
                           
                         
                         
                           24.50 
                         
                         
                           83.50 
                         
                       
                       
                         
                           52.50 
                         
                         
                           42.50 
                         
                         
                           
                             - 
                             141.50 
                           
                         
                         
                           46.50 
                         
                       
                       
                         
                           
                             - 
                             84.50 
                           
                         
                         
                           
                             - 
                             108.50 
                           
                         
                         
                           101.50 
                         
                         
                           91.50 
                         
                       
                       
                         
                           2.75 
                         
                         
                           6.75 
                         
                         
                           
                             - 
                             16.25 
                           
                         
                         
                           6.75 
                         
                       
                       
                         
                           5.50 
                         
                         
                           
                             - 
                             9.50 
                           
                         
                         
                           31.50 
                         
                         
                           
                             - 
                             27.50 
                           
                         
                       
                       
                         
                           
                             - 
                             8.00 
                           
                         
                         
                           1.00 
                         
                         
                           
                             - 
                             2.00 
                           
                         
                         
                           9.00 
                         
                       
                       
                         
                           
                             - 
                             127.25 
                           
                         
                         
                           
                             - 
                             110.25 
                           
                         
                         
                           115.75 
                         
                         
                           121.75 
                         
                       
                       
                         
                           49.50 
                         
                         
                           49.50 
                         
                         
                           
                             - 
                             148.50 
                           
                         
                         
                           49.50 
                         
                       
                       
                         
                           47.00 
                         
                         
                           
                             - 
                             168.00 
                           
                         
                         
                           56.00 
                         
                         
                           65.00 
                         
                       
                     
                     ] 
                   
                 
               
               
                 
                   ( 
                   5 
                   ) 
                 
               
             
           
         
       
     
     A covariance matrix Ω may be calculated from the intermediate matrix  X  at S 350 . The covariance matrix Ω may be calculated as follows: 
     
       
         
           
             
               
                 
                   
                     
                       
                         Q 
                         = 
                           
                          
                         
                           
                             X 
                             _ 
                           
                            
                           
                             
                               X 
                               T 
                             
                             _ 
                           
                         
                       
                     
                   
                   
                     
                       
                         = 
                           
                          
                         
                           [ 
                           
                             
                               
                                 36517 
                               
                               
                                 
                                   - 
                                   3639 
                                 
                               
                               
                                 23129 
                               
                               
                                 
                                   - 
                                   778 
                                 
                               
                               
                                 304 
                               
                               
                                 113 
                               
                               
                                 24000 
                               
                               
                                 
                                   - 
                                   4851 
                                 
                               
                               
                                 36446 
                               
                             
                             
                               
                                 
                                   - 
                                   3639 
                                 
                               
                               
                                 26747 
                               
                               
                                 
                                   - 
                                   19155 
                                 
                               
                               
                                 3045 
                               
                               
                                 
                                   - 
                                   5851 
                                 
                               
                               
                                 324 
                               
                               
                                 
                                   - 
                                   22083 
                                 
                               
                               
                                 28017 
                               
                               
                                 
                                   - 
                                   9574 
                                 
                               
                             
                             
                               
                                 23129 
                               
                               
                                 
                                   - 
                                   19155 
                                 
                               
                               
                                 37587 
                               
                               
                                 
                                   - 
                                   1997 
                                 
                               
                               
                                 1247 
                               
                               
                                 1188 
                               
                               
                                 45603 
                               
                               
                                 
                                   - 
                                   20097 
                                 
                               
                               
                                 25888 
                               
                             
                             
                               
                                 
                                   - 
                                   778 
                                 
                               
                               
                                 3045 
                               
                               
                                 
                                   - 
                                   1996 
                                 
                               
                               
                                 363 
                               
                               
                                 
                                   - 
                                   746.5 
                                 
                               
                               
                                 78 
                               
                               
                                 
                                   - 
                                   2153 
                                 
                               
                               
                                 3217 
                               
                               
                                 
                                   - 
                                   1476 
                                 
                               
                             
                             
                               
                                 304 
                               
                               
                                 
                                   - 
                                   5851 
                                 
                               
                               
                                 1247 
                               
                               
                                 
                                   - 
                                   747 
                                 
                               
                               
                                 1869 
                               
                               
                                 
                                   - 
                                   364 
                                 
                               
                               
                                 645 
                               
                               
                                 
                                   - 
                                   6237 
                                 
                               
                               
                                 1831 
                               
                             
                             
                               
                                 113 
                               
                               
                                 324 
                               
                               
                                 1188 
                               
                               
                                 78 
                               
                               
                                 
                                   - 
                                   364 
                                 
                               
                               
                                 150 
                               
                               
                                 1772 
                               
                               
                                 396 
                               
                               
                                 
                                   - 
                                   71 
                                 
                               
                             
                             
                               
                                 24000 
                               
                               
                                 
                                   - 
                                   22083 
                                 
                               
                               
                                 45603 
                               
                               
                                 
                                   - 
                                   2153 
                                 
                               
                               
                                 645.5 
                               
                               
                                 1772 
                               
                               
                                 56569 
                               
                               
                                 
                                   - 
                                   22919 
                                 
                               
                               
                                 26937 
                               
                             
                             
                               
                                 
                                   - 
                                   4851 
                                 
                               
                               
                                 28017 
                               
                               
                                 
                                   - 
                                   20097 
                                 
                               
                               
                                 3218 
                               
                               
                                 
                                   - 
                                   6237 
                                 
                               
                               
                                 396 
                               
                               
                                 
                                   - 
                                   22919 
                                 
                               
                               
                                 29403 
                               
                               
                                 
                                   - 
                                   11088 
                                 
                               
                             
                             
                               
                                 36446 
                               
                               
                                 
                                   - 
                                   9574 
                                 
                               
                               
                                 25888 
                               
                               
                                 
                                   - 
                                   1476 
                                 
                               
                               
                                 1831 
                               
                               
                                 
                                   - 
                                   71 
                                 
                               
                               
                                 26937 
                               
                               
                                 
                                   - 
                                   11088 
                                 
                               
                               
                                 37794 
                               
                             
                           
                           ] 
                         
                       
                     
                   
                 
               
               
                 
                   ( 
                   6 
                   ) 
                 
               
             
           
         
       
         
         wherein  X T    represents a transpose of the intermediate matrix  X . 
       
    
     Subsequently, eigenvalues may be calculated from the covariance matrix Ω, and then eigenvectors corresponding to the respective eigenvalues may be calculated. In one embodiment, by way of non-limiting example, the eigenvalues and the eigenvectors may be calculated by using Jacobi algorithm. The eigenvectors may be structured to a matrix, which may represent an eigenspace, at S 360 . For example, the eigenvalues λ1-λ3 and the eigenvectors v 1 -v 3  of the covariance matrix Ω may be calculated as follows: 
     
       
         
           
             
               
                 
                   
                     
                       λ 
                        
                       
                           
                       
                        
                       1 
                     
                     = 
                     153520 
                   
                    
                   
                     
 
                   
                    
                   
                     
                       λ 
                        
                       
                           
                       
                        
                       2 
                     
                     = 
                     50696 
                   
                    
                   
                     
 
                   
                    
                   
                     
                       λ 
                        
                       
                           
                       
                        
                       3 
                     
                     = 
                     22781 
                   
                    
                   
                     
 
                   
                    
                   
                     
                       v 
                       1 
                     
                     = 
                     
                       [ 
                       
                         
                           
                             0.356 
                           
                         
                         
                           
                             
                               - 
                               0.279 
                             
                           
                         
                         
                           
                             0.480 
                           
                         
                         
                           
                             
                               - 
                               0.031 
                             
                           
                         
                         
                           
                             0.035 
                           
                         
                         
                           
                             0.009 
                           
                         
                         
                           
                             0.560 
                           
                         
                         
                           
                             
                               - 
                               0.296 
                             
                           
                         
                         
                           
                             0.402 
                           
                         
                       
                       ] 
                     
                   
                    
                   
                     
 
                   
                    
                   
                     
                       v 
                       2 
                     
                     = 
                     
                       [ 
                       
                         
                           
                             
                               - 
                               0.552 
                             
                           
                         
                         
                           
                             
                               - 
                               0.486 
                             
                           
                         
                         
                           
                             0.044 
                           
                         
                         
                           
                             
                               - 
                               0.048 
                             
                           
                         
                         
                           
                             0.105 
                           
                         
                         
                           
                             
                               - 
                               0.004 
                             
                           
                         
                         
                           
                             0.112 
                           
                         
                         
                           
                             0.492 
                           
                         
                         
                           
                             
                               - 
                               0.432 
                             
                           
                         
                       
                       ] 
                     
                   
                    
                   
                     
 
                   
                    
                   
                     
                       v 
                       3 
                     
                     = 
                     
                       [ 
                       
                         
                           
                             
                               - 
                               0.264 
                             
                           
                         
                         
                           
                             0.347 
                           
                         
                         
                           
                             0.309 
                           
                         
                         
                           
                             0.064 
                           
                         
                         
                           
                             
                               - 
                               0.222 
                             
                           
                         
                         
                           
                             0.078 
                           
                         
                         
                           
                             0.585 
                           
                         
                         
                           
                             0.401 
                           
                         
                         
                           
                             
                               - 
                               0.391 
                             
                           
                         
                       
                       ] 
                     
                   
                 
               
               
                 
                   ( 
                   7 
                   ) 
                 
               
             
           
         
       
     
     The eigenspace V may be formed by using the eigenvectors v 1 -v 3 , as follows: 
     
       
         
           
             
               
                 
                   V 
                   = 
                   
                     [ 
                     
                       
                         
                           0.356 
                         
                         
                           
                             - 
                             0.552 
                           
                         
                         
                           
                             - 
                             0.264 
                           
                         
                       
                       
                         
                           
                             - 
                             0.279 
                           
                         
                         
                           
                             - 
                             0.489 
                           
                         
                         
                           0.347 
                         
                       
                       
                         
                           0.480 
                         
                         
                           0.044 
                         
                         
                           0.309 
                         
                       
                       
                         
                           
                             - 
                             0.031 
                           
                         
                         
                           
                             - 
                             0.048 
                           
                         
                         
                           0.064 
                         
                       
                       
                         
                           0.035 
                         
                         
                           0.105 
                         
                         
                           
                             - 
                             0.222 
                           
                         
                       
                       
                         
                           0.009 
                         
                         
                           
                             - 
                             0.004 
                           
                         
                         
                           0.078 
                         
                       
                       
                         
                           0.560 
                         
                         
                           0.112 
                         
                         
                           0.585 
                         
                       
                       
                         
                           
                             - 
                             0.296 
                           
                         
                         
                           0.492 
                         
                         
                           0.401 
                         
                       
                       
                         
                           0.402 
                         
                         
                           
                             - 
                             0.432 
                           
                         
                         
                           
                             - 
                             0.391 
                           
                         
                       
                     
                     ] 
                   
                 
               
               
                 
                   ( 
                   8 
                   ) 
                 
               
             
           
         
       
     
     Thereafter, at S 370 , the first feature vectors of the respective plane images corresponding to the respective standard views may be calculated by using the intermediate vectors calculated at S 330  and the eigenspace formed at S 360 . In one embodiment, by way of non-limiting example, the intermediate vectors  x 1   -  x 4    may be projected into the eigenspace V to thereby obtain the feature vectors {circumflex over (x)}{circumflex over (x 1 )}-{circumflex over (x)}{circumflex over (x 4 )}, as follows: 
     
       
         
           
             
               
                 
                   
                     
                       
                         x 
                         ^ 
                       
                       1 
                     
                     = 
                     
                       
                         
                           V 
                           
                             x 
                             1 
                           
                           T 
                         
                         _ 
                       
                       = 
                       
                         [ 
                         
                           
                             
                               
                                 - 
                                 103.09 
                               
                             
                           
                           
                             
                               
                                 - 
                                 117.31 
                               
                             
                           
                           
                             
                               
                                 - 
                                 96.57 
                               
                             
                           
                         
                         ] 
                       
                     
                   
                    
                   
                     
 
                   
                    
                   
                     
                       
                         x 
                         ^ 
                       
                       2 
                     
                     = 
                     
                       
                         
                           V 
                           
                             x 
                             2 
                           
                           T 
                         
                         _ 
                       
                       = 
                       
                         [ 
                         
                           
                             
                               
                                 - 
                                 265.92 
                               
                             
                           
                           
                             
                               98.29 
                             
                           
                           
                             
                               47.45 
                             
                           
                         
                         ] 
                       
                     
                   
                    
                   
                     
 
                   
                    
                   
                     
                       
                         x 
                         ^ 
                       
                       3 
                     
                     = 
                     
                       
                         
                           V 
                           
                             x 
                             3 
                           
                           T 
                         
                         _ 
                       
                       = 
                       
                         [ 
                         
                           
                             
                               229.76 
                             
                           
                           
                             
                               125.90 
                             
                           
                           
                             
                               
                                 - 
                                 46.14 
                               
                             
                           
                         
                         ] 
                       
                     
                   
                    
                   
                     
 
                   
                    
                   
                     
                       
                         x 
                         ^ 
                       
                       4 
                     
                     = 
                     
                       
                         
                           V 
                           
                             x 
                             4 
                           
                           T 
                         
                         _ 
                       
                       = 
                       
                         [ 
                         
                           
                             
                               139.24 
                             
                           
                           
                             
                               
                                 - 
                                 106.88 
                               
                             
                           
                           
                             
                               95.26 
                             
                           
                         
                         ] 
                       
                     
                   
                 
               
               
                 
                   ( 
                   9 
                   ) 
                 
               
             
           
         
       
         
         wherein V T  represents a transpose of the eigenspace V. The processing unit  140  may be operable to form a mapping table by using the feature vectors {circumflex over (x)}{circumflex over (x 1 )}-{circumflex over (x)}{circumflex over (x 4 )} at S 380 . 
       
    
       FIG. 5  is a block diagram showing an illustrative embodiment of the processing unit  140 . The processing unit  140  may include an initial vector establishing section  141 . The initial vector establishing section  141  may be operable to establish an initial vector based on the pixel values of the ultrasound image provided from the ultrasound image forming unit  130 . In one embodiment, the initial vector establishing section  141  may be operable to establish the initial vector by transforming pixel values of the ultrasound image into a 1-dimensional matrix (i.e., 1×N), wherein N is the number of the pixels. For example, assuming that an ultrasound image  600  is provided, as shown in  FIG. 6 , the initial vector y may be established by taking the pixel values in the ultrasound image  600  in a horizontal direction, as follows: 
     
       
         
           
             
               
                 
                   y 
                   = 
                   
                     [ 
                     
                       
                         
                           20 
                         
                       
                       
                         
                           244 
                         
                       
                       
                         
                           44 
                         
                       
                       
                         
                           246 
                         
                       
                       
                         
                           21 
                         
                       
                       
                         
                           244 
                         
                       
                       
                         
                           4 
                         
                       
                       
                         
                           255 
                         
                       
                       
                         
                           2 
                         
                       
                     
                     ] 
                   
                 
               
               
                 
                   ( 
                   10 
                   ) 
                 
               
             
           
         
       
     
     The processing unit  140  may further include an intermediate vector forming section  142 . The intermediate vector forming section  142  may be operable to subtract a mean vector from the initial vector to thereby obtain an intermediate vector. In one embodiment, the stored mean vector in the storage unit  110  may be used as the mean vector. For example, the intermediate vector forming section  142  may be operable to obtain the intermediate vector  y , as follows: 
     
       
         
           
             
               
                 
                   
                     y 
                     _ 
                   
                   = 
                   
                     [ 
                     
                       
                         
                           
                             - 
                             151.50 
                           
                         
                       
                       
                         
                           67.50 
                         
                       
                       
                         
                           
                             - 
                             88.5 
                           
                         
                       
                       
                         
                           
                             - 
                             2.25 
                           
                         
                       
                       
                         
                           
                             - 
                             6.50 
                           
                         
                       
                       
                         
                           
                             - 
                             2.00 
                           
                         
                       
                       
                         
                           
                             - 
                             123.25 
                           
                         
                       
                       
                         
                           49.50 
                         
                       
                       
                         
                           
                             - 
                             168.00 
                           
                         
                       
                     
                     ] 
                   
                 
               
               
                 
                   ( 
                   11 
                   ) 
                 
               
             
           
         
       
     
     The processing unit  140  may further include a covariance matrix calculating section  143 . The covariance matrix calculating section  143  may be operable to calculate a covariance matrix from the intermediate matrix. The calculation of the covariance matrix may be performed in the same manner with the operation of S 350  in  FIG. 3 . Thus, the detailed description of calculating the covariance matrix may be omitted herein. 
     The processing unit  140  may further include an eigenspace forming section  144 . The eigenspace forming section  144  may be operable to calculate eigenvalues and eigenvectors from the covariance matrix calculated in the covariance matrix calculating section  143 . In one embodiment, by way of non-limiting example, the eigenvalues and the eigenvectors may be calculated by using Jacobi algorithm. The eigenspace forming section  144  may be further operable to form an eigenspace by using the eigenvalues and eigenvectors. The eigenspace forming section  144  may be operable to form the eigenspace similar to the operation of S 360  in  FIG. 3 . 
     The processing unit  140  may further include a feature vector calculating section  145 . The feature vector calculating section  145  may be operable to calculate a second feature vector by using the intermediate vector calculated in the intermediate vector forming section  142  and the eigenspace formed in the eigenspace forming section  144 . In one embodiment, by way of non-limiting example, the feature vector calculating section  145  may be operable to project the intermediate vector  y  into the eigenspace V to thereby obtain the second feature vector ŷ, as follows: 
     
       
         
           
             
               
                 
                   
                     y 
                     ^ 
                   
                   = 
                   
                     
                       
                         V 
                         y 
                         T 
                       
                       _ 
                     
                     = 
                     
                       [ 
                       
                         
                           
                             
                               - 
                               266.65 
                             
                           
                         
                         
                           
                             80.75 
                           
                         
                         
                           
                             50.60 
                           
                         
                       
                       ] 
                     
                   
                 
               
               
                 
                   ( 
                   12 
                   ) 
                 
               
             
           
         
       
     
     The processing unit  140  may further include a standard view detecting section  146 . The standard view detecting section  146  may be operable to retrieve the mapping table to detect a standard view corresponding to the second feature vector calculated in the feature vector calculating section  145 . In one embodiment, the standard view detecting section  146  may be operable to compute an Euclidean distance between the second feature vector and each of the first feature vectors of the mapping table stored in the storage unit  110  to detect the corresponding standard view. That is, the standard view detecting section  146  may be operable to select one of the first feature vectors, which has the closest Euclidean distance, and access the storage unit  100  to find one of the standard views corresponding to the selected first feature vector from the mapping table. The extracted information may be displayed on a screen of the display unit  150 . 
     Although the ultrasound image forming unit  130  and the processing unit  140  are described in different elements in one embodiment, the ultrasound image forming unit  130  and the processing unit  140  may be embodied in a single processor. Also, although it is described above that the feature vectors are calculated by using principle component analysis in one embodiment, the feature vectors may be calculated by other statistical algorithm, such as Hidden Markov model, support vector machine algorithm, etc. 
     Although embodiments have been described with reference to a number of illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this disclosure. More particularly, numerous variations and modifications are possible in the component parts and/or arrangements of the subject combination arrangement within the scope of the disclosure, the drawings and the appended claims. In addition to variations and modifications in the component parts and/or arrangements, alternative uses will also be apparent to those skilled in the art.