Figure 1

The dedicated RF needle and ex vivo marker results. a-c) Monopolar electrode engineered to affix the histological marker. Note the hemicylindrical proximal cut of the PFTE isolator sheath (arrow) and electrical clamp at this site. Deployment of the electrical field around the tip is also illustrated. d). Ex-vivo T1w image (VIBE 3D isotropic sequence) of four independent thermal lesions (see red arrows) obtained post-RF ablation. The upper lesions correspond to a coagulated spherical area created without injection of the Gd-doped staining and the lower lesions were obtained after standard fixation of the marker, with injection of Gd-doped methylene blue. e). Macroscopic slice showing the optimal RF thermal lesion, visible as a white spheroidal volume of colorless tissue (non-injected procedure). f) - h). Ex vivo macroscopic slices of volumetric MRgHIFU ablation, cut perpendicular to the focal plane, showing the coagulative lesions successfully centered on the ballistic target (high intensity blue spot in three different slices). The prescribed patterns of sonication were 7 x 2 foci, 6 x 2 foci and 3 x 2 foci, respectively, 4 mm inter-foci gap, with a delivered energy of 18 kJ, 15.4 kJ and 7.7 kJ, respectively.