Thermal ablation produced using a surgical toroidal high-intensity focused ultrasound device is independent from...

In the liver, the efficacy of radiofrequency or high-intensity focused ultrasound (HIFU) ablation is impaired by blood perfusion. This can be overcome by hepatic inflow occlusion. Here we report the in vivo evaluation of ablations performed in the liver using a surgical toroidal HIFU device used during an open procedure with and without hepatic inflow occlusion. The HIFU device was composed of 256 toroidal-shaped emitters working at 3 MHz and an integrated ultrasound imaging probe working at 7.5 MHz. Using an intermittent Pringle maneuver (IPM), thermal ablations were created in three pigs with hepatic inflow occlusion (IPM group) and in three pigs with normal perfusion (NoIPM group). The ablations were studied on sonograms, macroscopically and microscopically 14 days after the treatment. In the NoIPM group, the average coagulated volume obtained after a 40 s exposure was 7.4 +/- 3.8 cm(3) (2.2-16.6). In the IPM group, the average ablated volume was 6.3 +/- 2.9 cm(3) (2.6-12.1). There was no significant difference between the two groups in terms of ablated volume (p = 0.25), diameter (p = 0.37) or depth (p = 0.61). Therefore, a toroidal-shaped HIFU device allows treatment in the liver that can be considered as independent from hepatic inflow occlusion.