The Preliminary Study Of Coagulation Necrosis Tissue Under Ultasound Speckle Anaysis

Background and PurposeHIFU is based on the imaging techniques, it would never make progress without the development of imaging technology .Ultrasound has been regard as one of the most potential monitored methods as its speed, no radiation,and simple.The substance of ultrasound to monitor is that there will be echo enhancement phenomenon after HIFU treatment caused by the scattering of cavitation bubbles. While,as time goes by this phenomenon will gradually weaken or even disappear, and the gray value does not correspond to the actually size of tissue damage area.In this paper a new method has been proposed according to the shortcomings were discussed,by comparing the similarity of monitoring images before HIFU treatment to after.Research MethodsJC-200 High-intensity focused ultrasound tumor therapy system has been used to radiate in vitro bovine liver with 90 w,time continues from 1 s,2s until 15s. Ultrasonographic of before HIFUradiation and immediately after radiation,1 min after radiation ,2min after radiation,3 min after radiation have been saved.According to the principles of ultrasound speckle analysis Matlab 7.0 has been used to obtain ROI,and then analysised the similarity of different images by two kinds of similarity measures .Results1) Gray Val 1.0 judge the results obtained Compared with the pathological results, in this study, the accuracy of Gray Val 1.0 was 64.0%, the error rate was 34.0%2) Cross correlation similarity has been used as the a measure to evaluate coagulation necrosis .The cross correlation similarity is less than 0.79 when both Gray Val 1.0 Calculation of target gray-scale ultrasonography before and after radiation the difference is greater than 5 and the pathological result is positive..The cross correlation similarity is less than 0.85 when both Gray Val 1.0 Calculation of target gray-scale ultrasonography before and after radiation the difference is less than 5 and the pathological result is positive.3) Normalized mutual information similarity has been used as the a measure to evaluate coagulation necrosis too.This method is more sensitive to noise.Simple evaluation of 2 different time speckle images before HIFU treatment I(A,B) are over 0.650,and even some samples to 0.700.With longer time of treatment,althogh the speckle pattern has significant changes,normalized mutual information values increased slowly (less than 0.100)In summary,speckle analysis would be a new method to detect coagulation necrosis.However how to choose the most suitable similarity measure and the size of ROI is the key way to make success.