System and method of ultrasound image processing

Abstract

An ultrasound system includes an ultrasound transducer adapted to obtain a dynamic series of echo signals of a subject tissue at different deformation states, and an image processor for generating and displaying ultrasound images of the tissue. The processor is configured to generate dynamic images that correspond to the dynamic series of echo signals, identify a plurality of pixels within a region of interest (ROI) of a first of the generated images, evaluate local tissue mechanical behavior by tracking the displacement, deformation, and echo intensity of the identified plurality of pixels from the first image to subsequent images based on groups of pixels that correspond to each of the identified plurality of pixels, determine tissue functionality in the subject at the tracked pixel locations, and display the tissue functionality in dynamic images that corresponds to the tracked pixel locations.

What is claimed is: 
     
         1 . A non-transitory computer readable storage medium having stored thereon a computer program comprising instructions which when executed by one or more computers cause the one or more computers to:
 access a first image and a second image generated from a dynamic series of echo signals of a tissue acquired using an ultrasound transducer, wherein the second image represents the tissue at a different state of deformation than the first image;   identify a location of a first plurality of pixels representing the tissue in the first image;   assume a location of a second plurality of pixels representing the tissue in the second image;   compare echo signals of the first plurality of pixels to echo signals of the second plurality of pixels;   derive actual locations of the second plurality of pixels based on the comparison;   calculate a deformation of the tissue between the first image and the second image from the derived actual locations of the second plurality of pixels; and   output functionality information of the tissue based on the deformation.   
     
     
         2 . The non-transitory computer readable storage medium of  claim 1  wherein the instructions cause the computer to compute the functionality information of the tissue based on a comparison of echo intensities between the first image and the second image with respect to the deformation. 
     
     
         3 . The non-transitory computer readable storage medium of  claim 1  wherein the instructions cause the computer to overlay the functionality information on at least one of the first image and the second image. 
     
     
         4 . The non-transitory computer readable storage medium of  claim 1  wherein the first plurality of pixels comprises a first target pixel and a plurality of pixels located in a neighbor-region of the first target pixel;
 wherein the second plurality of pixels comprises a second target pixel and a plurality of pixels located in a neighbor-region of the second target pixel; and 
 wherein the instructions further cause the computer to:
 identify coordinates of the first target pixel; 
 assume coordinates of the second target pixel; 
 compare an echo intensity of the first target pixel to an echo intensity of the second target pixel; and 
 determine whether the second target pixel represents the same tissue as the first target pixel based on the comparison. 
 
 
     
     
         5 . The non-transitory computer readable storage medium of  claim 1  wherein the first image comprises a representation of the tissue in a non-deformed state. 
     
     
         6 . The non-transitory computer readable storage medium of  claim 5  wherein the instructions further cause the computer to iteratively adjust an assumed location of the second plurality of pixels if a difference between the echo signals of the second plurality of pixels and the echo signals of the first plurality of pixels exceeds a threshold. 
     
     
         7 . A method comprising:
 acquiring a dynamic series of echo signals of a tissue using an ultrasound transducer;   generating a first image and a second image from the dynamic series of echo signals, wherein the second image represents the tissue at a different state of deformation than the first image;   identifying a location of a first plurality of pixels representing the tissue in the first image;   assuming a location of a second plurality of pixels representing the tissue in the second image;   comparing echo signals of the first plurality of pixels to echo signals of the second plurality of pixels;   deriving actual locations of the second plurality of pixels based on the comparison;   calculating a deformation of the tissue between the first image and the second image from the derived actual locations of the second plurality of pixels; and   outputting functionality information of the tissue based on the deformation.   
     
     
         8 . The method of  claim 7  further comprising computing the functionality information of the tissue based on a comparison of echo intensities between the first image and the second image with respect to the deformation. 
     
     
         9 . The method of  claim 7  further comprising deriving the actual locations of the second plurality of pixels by iteratively adjusting an assumed location of the second plurality of pixels. 
     
     
         10 . The method of  claim 7  further comprising:
 manually selecting a first pixel of the first plurality of pixels in the first image; and 
 automatically selecting other pixels of the first plurality of pixels, the other pixels comprising pixels located in a neighbor-region of the first pixel. 
 
     
     
         11 . The method of  claim 7  further comprising simultaneously monitoring a displacement of the tissue, a deformation of the tissue, and an echo intensity of the first plurality of pixels. 
     
     
         12 . The method of  claim 7  wherein outputting functionality information of the tissue comprises at least one of:
 generating a composite image having the functionality information overlaid on an image of the tissue; 
 generating a histogram; and 
 generating a probability density function plot. 
 
     
     
         13 . An ultrasound system comprising:
 an ultrasound transducer adapted to obtain a dynamic series of echo signals of a tissue at different deformation states; and   one or more processors configured to:
 access a series of images that correspond to the dynamic series of echo signals; 
 identify a target pixel within a first image of the series of images, the target pixel representing tissue of a patient; 
 define a neighbor-region of pixels surrounding the target pixel; 
 simultaneously monitor a displacement of the tissue represented within the target pixel, a deformation of tissue represented within the neighbor-region of pixels, and an echo intensity of pixels representing the tissue from the first image to at least one subsequent image of the series of images; and 
 generate a functionality indicator for the tissue based on the monitored displacement, echo intensity, and deformation. 
   
     
     
         14 . The ultrasound system of  claim 13  further comprising:
 a first processor configured to generate the series of images that correspond to the dynamic series of echo signals; and 
 a second processor configured to:
 access the series of images; 
 identify the target pixel; 
 define the neighbor-region of pixels; 
 monitor the displacement, tissue deformation, and echo intensity; and 
 generate the functionality indicator. 
 
 
     
     
         15 . The ultrasound system of  claim 13  wherein the functionality indicator comprises one of a histogram and a probability density function plot. 
     
     
         16 . The ultrasound system of  claim 13  wherein the image processor is further configured to:
 select a plurality of target pixels with the first image of the series of images; 
 define a plurality of neighbor-regions of pixels, each of the plurality of neighbor-regions of pixels surrounding a respective target pixel; and 
 monitor a displacement of tissue represented within the plurality of target pixels, an echo intensity of the plurality of target pixels, and a deformation of the plurality of neighbor-regions of pixels from the first image to subsequent images of the series of images. 
 
     
     
         17 . The ultrasound system of  claim 13  wherein the first image comprises an image of the tissue in an undeformed state. 
     
     
         18 . The ultrasound system of  claim 13  wherein the image processor is further configured to automatically define the neighbor-region of pixels following selection of the target pixel. 
     
     
         19 . The ultrasound system of  claim 13  wherein the image processor is further configured to generate a composite image comprising an image of the tissue having the displayed functionality overlaid thereon. 
     
     
         20 . The ultrasound system of  claim 19  wherein the displayed functionality is displayed according to a tissue functionality color map. 
     
     
         21 . The ultrasound system of  claim 13  wherein the image processor is further configured to:
 identify coordinates of the target pixel in the first image; 
 estimate a displacement of the tissue represented by the target pixel from the first image to a subsequent image; 
 identify coordinates of a displaced target pixel in the subsequent image based on the estimated displacement; 
 compare an echo intensity of the target pixel in the first image to an echo intensity of the displaced target pixel; and 
 determine whether the displaced target pixel represents the same tissue as the target pixel based on the comparison. 
 
     
     
         22 . The ultrasound system of  claim 21  wherein the image processor is configured to:
 use a mathematical norm to compare the echo intensities; and 
 if the mathematical norm exceeds a threshold, estimate new coordinates of the target pixel and the neighbor-region; and 
 if the mathematical norm is less than the threshold, use the estimated coordinates as the coordinates of the target pixel and the neighbor-region in the subsequent image. 
 
     
     
         23 . The ultrasound system of  claim 21  wherein the processor is further configured to iteratively estimate new coordinates of the target pixel and the neighbor region.