ABSTRACT
Objective To assess the influence of pre-exposure to non-ablating ultrasound on the effect of high intensity focused ultrasound(HIFU)ablation.Methods Forty rabbits with transplanted VX2 tumors on their livers were divided into three pre-exposure groups(60 W,80 W and 100 W)and a control group(O W),with 10 rabbits in each group.Each group was pre-exposed to lower intensity focused ultrasound at the corresponding power.From each group,5 rabbits were randomly selected to be exposed to HIFU on the next day.Each group received 14scans.The rabbits were sacrificed 24 h later to take tissue samples for tfipheny tetrazolium chloride(TTC)staining to measure the amount of coagulative necrosis.Hematoxylin and eosin(HE)staining and succinate dehydrogenase (SDH)were also measured to observe the structure and activation of pre-exposed tumors.Results After HIFU exposure,the ablated volumes increased with pre-exposure acoustic intensity,and all volumes were larger than those in the control group.The ablating efficiency in the 100 W group was the highest.The pre-exposure did not itself ablate tumor tissue,but in the 80 W and 100 W groups the structure and activation of the tissues changed.Those in the 60 W group were not obviously altered.Conclusion Prior exposure to non-ablating ultrasound can highly enhance the efficacy of HIFU ablation.
ABSTRACT
Objective To observe the pathological regression of rabbit liver after the low-dose irradiation with high intensity focused ultrasound (HIFU), and to explore the role and mechanism of the irradiation in changing acoustic environment of rabbit liver. Methods Pathological study was performed in 10 New Zealand white rabbits, the livers were observed under light and electron microscope. The observation was done immediately after low-dose HIFU irradiation and in 2, 3, 5, 7 days after the low-dose irradiation with HIFU. Results Light microscope changes: Edema existed in hepatocytes after irradiation instantly, congestion and aggravated edema were found at 2-3 days, then the injured cells recovered gradually. Electron microscope changes: Detached endothelial cells of hepatic sinusoid and swelling organelles were observed after irradiation, while 2 or 3 days later, erythrocyte aggregation was found in hepatic sinusoid and cavitation was found in cytoplasm. Thereafter, organelles swelling reduced till resumed to normal. Conclusion Low-dose HIFU irradiation can make corresponding changes to the acoustic environment of rabbit liver.
ABSTRACT
Objective To compare the two ways of twice irradiation on the rabbit liver VX2 tumor using high intensity focused ultrasound (HIFU).Methods Totally 45 tumor-bearing rabbits were randomly divided into 3 groups:group A(one-time irradiation group) received a one-time ablation;group B and C(twice irradiation group) firstly received a low-dose irradiation(without ablation),then group B received ablation on the next day while group C received it 2 days later.Results Compared with one-time irradiation group,the total treatment time of twice irradiation group was not significantly different,but the time of each irradiation,the incidence of skin erythema and the energy efficiency factor(EEF)were less,and that of group B were the least.After ablation,the typical coagulation necrosis in tumor tissues occurred,and the recurrence and metastasis were effectively controlled in all the three groups.Conclusion The total treatment time and efficacy of twice irradiation were same as one-time ablation,but the time and dose of each irradiation significantly decreased,the damage efficiency was enhanced and the complications were reduced.The way of continuous two-days twice irradiation was the most effective,which would be a safe and effective method of HIFU treatment.