System and method for ultrasonic harmonic imaging for therapy guidance and monitoring

Abstract

An ultrasound system is provided which includes a therapy ultrasound transducer and a diagnostic ultrasound transducer and operates in accordance with a method to direct the application of the therapy ultrasound. The method includes operating the diagnostic ultrasound transducer to acquire a first ultrasound image; simultaneously operating the diagnostic ultrasound transducer and therapy ultrasound transducer for a second interval to acquire a second ultrasound image; and determining a difference in the first and second images indicative of the pattern of the therapy ultrasound transducer signal. The difference in the images, which result from enhanced non-linearities and propagation distortions induced by the high intensity therapy ultrasound, can be obtained by subtracting the two images. A method is also provided for monitoring the progress of high intensity therapy ultrasound which evaluates transient changes due to in-situ heating as well as permanent changes which result from cell microstructure alteration.

What is claimed is:  
     
         1 . A method for ultrasonic imaging comprising: 
 acquiring a non-linearity imaging scan in a region including a target for application of an ultrasonic therapy beam, said acquiring taking place in the presence of the ultrasonic therapy beam; and    displaying the acquired non-linearity imaging scan.    
     
     
         2 . The method of  claim 1 , wherein the non-linearity imaging scan is a harmonic imaging scan.  
     
     
         3 . The method of  claim 1 , wherein the non-linearity imaging scan acquires the reflected harmonic components of the ultrasonic therapy beam.  
     
     
         4 . A method of monitoring the application of a focused ultrasonic therapy beam comprising: 
 acquiring a first image scan using a first frequency ultrasound signal;    acquiring a second image scan using the first frequency ultrasound signal in the presence of a therapy beam ultrasound signal; and    determining difference properties in the first and second images descriptive of the therapy ultrasound signal.    
     
     
         5 . The method of monitoring the application of a therapy beam of  claim 4 , further comprising: 
 generating a difference image from the first image scan and second image scan; and    superimposing the difference image on the first image scan.    
     
     
         6 . The method of monitoring the application of a therapy beam of  claim 4 , wherein the second image scan is a non-linearity imaging scan.  
     
     
         7 . The method of monitoring the application of a therapy beam of  claim 6 , wherein the non-linearity imaging scan is a harmonic imaging scan.  
     
     
         8 . The method of monitoring the application of a therapy beam of  claim 6 , wherein the non-linearity imaging scan is a pulse inversion imaging scan.  
     
     
         9 . The method of monitoring the application of a therapy beam of  claim 5 , including the step of digitally enhancing the difference image between said generating and superimposing operations.  
     
     
         10 . The method of monitoring the application of a therapy beam of  claim 4 , wherein the difference properties are detected by evaluating mixing products of the first frequency ultrasound signal and the therapy beam ultrasound signal.  
     
     
         11 . The method of monitoring the application of a therapy beam of  claim 4 , wherein the difference properties are detected by evaluating harmonic components of the first frequency ultrasound signal.  
     
     
         12 . The method of monitoring the application of a therapy beam of  claim 4 , wherein the difference properties are detected by evaluating harmonic components of the therapy ultrasound signal.  
     
     
         13 . A method of operating an ultrasound therapy system having a therapy ultrasound transducer and a diagnostic ultrasound transducer, comprising: 
 operating the diagnostic ultrasound transducer for a first interval to acquire first ultrasound image scan data;    operating the diagnostic ultrasound transducer and therapy ultrasound transducer for a second interval to acquire second ultrasound image scan data; and    determining a difference in the first and second image scan data descriptive of the therapy ultrasound transducer signal.    
     
     
         14 . The method of operating an ultrasound therapy system of  claim 13 , further comprising: 
 generating a difference image from the first ultrasound image and second ultrasound image scan data; and    superimposing the difference image on the first image scan data.    
     
     
         15 . The method of operating an ultrasound therapy system of  claim 14 , further comprising digitally enhancing the difference image between said generating and superimposing operations.  
     
     
         16 . The method of operating an ultrasound therapy system of  claim 13 , wherein the difference in the image scan data is detected by evaluating mixing products of the diagnostic ultrasound signal and the therapy beam ultrasound signal.  
     
     
         17 . The method of operating an ultrasound therapy system of  claim 13 , wherein the difference in the image scan data are detected by evaluating harmonic components of the diagnostic ultrasound signal.  
     
     
         18 . The method of operating an ultrasound therapy system of  claim 13 , wherein the difference in the image scan data are detected by evaluating harmonic components of the therapy beam ultrasound signal.  
     
     
         19 . The method of operating an ultrasound therapy system of  claim 13 , wherein the second image scan is a non-linearity imaging scan.  
     
     
         20 . The method of operating an ultrasound therapy system of  claim 19 , wherein the non-linearity imaging scan is a harmonic imaging scan.  
     
     
         21 . The method of operating an ultrasound therapy system of  claim 19 , wherein the non-linearity imaging scan is a pulse inversion imaging scan.  
     
     
         22 . A method of monitoring ultrasound therapy comprising: 
 acquiring a first non-linearity image scan of a region;    applying high intensity ultrasound to a region for a first time period;    acquiring a second non-linearity image scan of the region;    determining differences in the first and second non-linearity image scans to evaluate an induced effect in the region.    
     
     
         23 . The method of monitoring an ultrasound therapy system of  claim 22 , further comprising: 
 discontinuing the high intensity ultrasound for a second time period;    acquiring a third non-linearity imaging scan;    determining transient changes in the region based on the third and second scans; and    determining permanent changes in the region based on the third and first scans.    
     
     
         24 . The method of monitoring an ultrasound therapy system of  claim 22 , wherein the first non-linearity imaging scan is acquired while the high intensity ultrasound being applied.  
     
     
         25 . The method of monitoring an ultrasound therapy system of  claim 22 , wherein the second non-linearity imaging scan is acquired while the high intensity ultrasound being applied.  
     
     
         26 . The method of monitoring an ultrasound therapy system of  claim 22 , wherein each of the first and second non-linearity imaging scans are acquired without the high intensity ultrasound being applied.  
     
     
         27 . A method of operating an ultrasound therapy system having a therapy ultrasound transducer and a diagnostic ultrasound transducer, comprising: 
 applying a first frequency signal to a region from the therapy ultrasound transducer for a first interval;    operating the diagnostic ultrasound transducer to acquire harmonic signals of the first frequency from the region;    generating an ultrasound image from the acquired harmonic signals.    
     
     
         28 . A method of monitoring ultrasound therapy comprising: 
 acquiring a first ultrasound image scan of the region;    applying high intensity ultrasound to a region for a first time period;    acquiring a second ultrasound image scan of the region;    discontinuing the high intensity ultrasound for a second time period;    acquiring a third ultrasound image scan;    determining transient non-linearity changes in the region; and    determining permanent non-linearity changes in the region.    
     
     
         29 . The method of monitoring ultrasound therapy of  claim 28  further comprising determining aggregate induced changes in the region by evaluating differences in the second and the first ultrasound image scans.  
     
     
         30 . The method of monitoring ultrasound therapy of  claim 28  wherein said first, second and third image scans are non-linearity imaging scans acquired in the presence of the high intensity ultrasound.  
     
     
         31 . The method of monitoring ultrasound therapy of  claim 30  wherein the non-linearity imaging scans are harmonic imaging scans.  
     
     
         32 . The method of monitoring ultrasound therapy of  claim 28 , wherein said first time period is selected to effect a therapeutic result from the high intensity ultrasound.  
     
     
         33 . The method of monitoring ultrasound therapy of  claim 28 , wherein said second time period is selected to allow in-situ cooling of the region subjected to the high intensity ultrasound.  
     
     
         34 . The method of monitoring ultrasound therapy of  claim 28 , wherein the transient changes are determined by subtracting one of the second image scan and third image scan from the other of the second image scan and third image scan.  
     
     
         35 . The method of monitoring ultrasound therapy of  claim 28 , wherein the permanent changes are determined by subtracting one of the first image scan and third image scan from the other of the first image scan and third image scan.