Method and apparatus to produce ultrasonic images using multiple apertures

Abstract

A combination of an ultrasonic scanner and an omnidirectional receive transducer for producing a two-dimensional image from received echoes is described. Two-dimensional images with different noise components can be constructed from the echoes received by additional transducers. These can be combined to produce images with better signal to noise ratios and lateral resolution. Also disclosed is a method based on information content to compensate for the different delays for different paths through intervening tissue is described. The disclosed techniques have broad application in medical imaging but are ideally suited to multi-aperture cardiac imaging using two or more intercostal spaces. Since lateral resolution is determined primarily by the aperture defined by the end elements, it is not necessary to fill the entire aperture with equally spaced elements. Multiple slices using these methods can be combined to form three-dimensional images.

What is claimed is: 
     
         1 . An ultrasound imaging method, comprising the steps of:
 transmitting an ultrasonic pulse into a target tissue with a first ultrasound transducer array;   receiving echoes from the ultrasonic pulse with the first ultrasound transducer array and with a second ultrasound transducer array;   digitizing and storing the echoes received by the first ultrasound transducer array and by the second ultrasound transducer array;   forming a first image with the echoes received by the first ultrasound transducer array;   forming a second image with the echoes received by the second ultrasound transducer array;   adjusting one or more variables of the second image to cause the first image and the second image to coincide; and   combining the first image with the second image.   
     
     
         2 . The method of  claim 1 , wherein adjusting one or more variables comprises adjusting one or more of a position (x 0 , y 0 , z 0 ) of the second ultrasound transducer array relative to the first ultrasound transducer array. 
     
     
         3 . The method of  claim 1 , wherein adjusting one or more variables comprises adjusting an average difference in time (D) for the ultrasound pulse and/or echoes to travel through the target tissue. 
     
     
         4 . The method of  claim 1 , wherein the first ultrasound transducer array is separated from the second ultrasound transducer array by a gap. 
     
     
         5 . The method of  claim 1 , wherein the first ultrasound transducer array and the second ultrasound transducer array are mounted in a rigid probe. 
     
     
         6 . The method of  claim 1 , wherein the first ultrasound transducer array and the second ultrasound transducer array are mounted in an adjustable, extendable, hand-held probe. 
     
     
         7 . The method of  claim 1 , wherein the first ultrasound transducer array and the second ultrasound transducer array are mounted using an adhesive mesh. 
     
     
         8 . The method of  claim 1 , wherein the first transducer array and the second transducer array are mounted in a fixture with articulated joints and sensors configured to measure relative positions of the first transducer array and the second transducer array.