Effects of low intensity ultrasound combined irradiation time to stimulate microbubble cavitation on renal carcinoma perfusion in nude mice
Objective To explore the effect of low-intensity ultrasound-induced microbubble cavitation on blood perfusion of renal carci-noma in nude mice under different irradiation durations.Methods Thirty male BALB/c nude mice were selected to establish a 786-O tumor model in the armpit.They were randomly divided into 3 groups according to the cavitation treatment time(T),namely group A(T=20 min)and group B(T=10 min),group C(T=5 min),10 animals in each group.Contrast imaging(CEUS)and microflow imaging(MFI)were performed pre-treatment and immediately,4 h,and 6 h after treatment;histological staining was performed to de-tect the microvascular status of the tumor after treatment.Results Compared with before treatment,the intratumoral blood perfusion in Group A increased immediately after treatment,and the PI and AUC values increased by 7.4％(P<0.05)and 10.6％(P<0.05)re-spectively;Tumor blood perfusion was significantly lower at 4 h and 6 h comparing to immediately after treatment(all P<0.05).The results of Group B showed that compared with pre-treatment,the PI values immediately,4 hours and 6 hours after treatment increased by 8.1％,15.1％and 3.1％respectively,and the corresponding AUC value growth rates were 18.7％and 31.2％.and 9.3％.The results of analysis of variance showed that there were significant differences in the PI and AUC values of each group(both P<0.01),and the differences in PI and AUC between the groups were statistically significant(both P<0.01);the results of group C showed that immediately after treatment,the blood perfusion in the tumor decreased 4 h and 6 h after treatment compared with pre-treatment.The intratumoral blood perfusion PI and AUC values were significantly reduced,and the differences were statistically significant compared with those before treatment(both P<0.05).The results of the difference analysis of visual scores among each group under MFI ima-ging were consistent with the conclusions of the contrast analysis.The pathological pictures showed that obvious blood vessel dilation was seen in group B,while in group C,the lumen was narrowed due to pressure,hemorrhage,and the density of microvessels was re-duced(P<0.01).Conclusion The treatment time of low-intensity ultrasound-excited microbubble cavitation affects tumor blood perfu-sion.In this study,the blood flow enhancement effect was optimal when the treatment time was 10 minutes.
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