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MR Guided Non Thermal Pulsed High Intensity Focused Ultrasound Therapy of Breast Cancer in Vivo

C Ma

C Ma*, X Chen, D Cvetkovic, L Chen, Fox Chase Cancer Center, Philadelphia, PA

TU-C-144-3 Tuesday 10:30AM - 12:30PM Room: 144

Purpose: High intensity focused ultrasound (HIFU) has been investigated for ablative therapy and drug enhancement for gene therapy and chemotherapy. The aim of this work is to explore the feasibility of pulsed high-intensity focused ultrasound (pHIFU) for non thermal cancer therapy using an in vivo animal model.

Methods: An InSightec ExAblate 2000 with a 1.5T GE MR scanner was used in this study. Suitable ultrasound parameters were investigated to perform non-thermal sonications. Breast tumor cells (107), MCF-7 line were injected subcutaneously in the flanks of the female mice (n = 12). When tumors reached the volume of 78 ± 28 mm3 as measured on MRI, the tumor-bearing mice (n = 6) were treated with pHIFU (1 MHz frequency; 25 W acoustic power; 0.1 duty cycle; 60 sec duration). A total of 4 to 6 sonications were used to cover the entire tumor volume under MR image guidance. The animals were allowed to survive for 4 weeks after the treatment. The tumor volume was measured on MRI weekly post treatment and was compared with that of the control group (n = 6).

Results:Significant tumor growth delay was observed in the tumor-bearing mice treated with pHIFU. The mean tumor volume for the pHIFU treated mice grew 3%, 17%, 11% at 1 week, 3 weeks and 4 weeks after the treatment, respectively, while the mean tumor volume of the control mice grew 25%, 41% and 48%, respectively, over the same time periods. Statistical analyses yielded p values P=0.034, P=0.005 and P=0.017 at 1 week, 3 weeks and 4 weeks post-treatment respectively.

Conclusion:Our results demonstrated that non-thermal pHIFU has a great potential for cancer therapy. Further experiments are needed to understand the cell killing mechanisms of pHIFU and to derive optimal ultrasound parameters and fractionation schemes to maximize the therapeutic effect of pHIFU.

Funding Support, Disclosures, and Conflict of Interest: DOD BC102806

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