An experimental study on high intensity focused ultrasound in the treatment of VX2 rabbit kidney tumors

Objective To investigate the effectiveness of high intensity focused ultrasound(HIFU) in the treatment of kidney tumors. Methods Fourteen New Zealand rabbits bearing VX2 kidney tumors were irradiated with HIFU at an intensity of 1200W/cm2 for 2 consecutive periods of 90s. Six other tumorbearing rabbits served as controls. The treated rabbits were sacrificed at different periods after irradiation to observe the pathological changes. Six of the treatment and the control group each were killed on the 14th day to study the growing condition of the primary tumors and the status of lung metastasis. Results Tumor cells underwent coagulation necrosis immediately after irradiation with HIFU. Irreversible destruction was observed under electron microscope. The primary tumors in 4 rabbits of the treatment group had been completely eradicated; while in the other two,one residual tumor was found beyond the target area in each rabbit. The size of the residual tumors was 62.8mm3 and 9.4mm3, while the average size of the primary tumors in the control group was 1 751.1353.7mm3.Lung metastasis took place in 2 rabbits of the treatment group,with 9 and 3 metastatic nodules respectively. Lung metastasis occured in all the control animals.The number of metastatic nodules was 5234. The difference between these two groups was significant. Conclusions HIFU should be effective in the treatment of kidney tumors.