Efficacy of MR-guided Focused Ultrasound Thermal Ablation of Rabbit VX2 Tumors

摘要

This animal study addresses the treatment efficacy of the MR-guided thermal ablation technique and temperature monitoring in rabbit tumors. Specifically, the relationship between the thermal dose coverage in the tumors and the rabbit survival rate was investigated. Two groups of rabbits (14 in back tumor group and 12 in thigh tumor group) were treated with the ExAblate-2000 MR-guided focused ultrasound thermal ablation system one week after being injected VX2 tumor cells into their back muscle or thigh muscle. Sonication was repeated twice in a planned location in the tumor region and monitored in the coronal and sagittal planes respectively to ensure volumetric thermal dose monitoring. MR T1 Gad-enhanced contrast images of the tumors were obtained immediately after treatment and post-treatment at 2, 4, 8 and 12 weeks (or before sacrificing the rabbits). In the thigh tumor rabbits group, tumor recurrence was observed for only one and the other eleven rabbits survived without tumor recurrence at 4 weeks. Aiming at a longer survival time, the rabbits with back tumors had up to 12 weeks survival time. Three rabbits survived to 12 weeks without tumor recurrence in the back tumor group, yielding less promising survival rate than that of the thigh tumor group survival test. Successful thermal ablation (i.e. lack of recurrence) was demonstrated when the tumors received full thermal dose coverage.