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Radiofrequency Ablation: In Vivo Comparison of Four Commercially Available Devices in Pig Livers¹

¹ From the Department of Diagnostic Radiology (P.L.P., J.T., I.S., C.T.R., D.S., C.D.S.), Section of Experimental Radiology (J.B.), and Departments of General Surgery (M.S.), Forensic Medicine (J.S.), and Pathology (S.K.), Eberhard-Karls-University, Hoppe-Seyler-Strasse 3, 72076 Tübingen, Germany. From the 2002 RSNA scientific assembly. Received February 13, 2003; revision requested May 1; final revision received October 31; accepted January 2, 2004. Address correspondence to P.L.P. (e-mail: philippe.pereira@med.uni-tuebingen.de).

View larger version (154K): [in a new window]   Figure 1a. (a) HiTT 106 perfusion electrode has micropores in needle tip for saline infusion. Digitally controlled syringe pump was connected to 60-W RF generator (frequency, 375 kHz) to provide continuous saline flow through micropores into surrounding tissue during ablation. (b) Cool Tip (internally cooled cluster) electrode was connected to new generation of 250-W RF generators (frequency, 480 kHz). Shafts of three internally cooled probes spaced 5 mm apart are electrically insulated with 2.5 cm of exposed active tip. Acrylic guide maintains correct interprobe distance. (c) RF 3000 (expandable 12-tine) electrode with curved tines fully deployed in configuration of an umbrella. Alternating electric-current generator was operated at 200 W (frequency, 480 kHz). RF waves emanate from each tine. (d) Model 1500 electrode (expandable nine-tine) electrode with curved tines fully deployed in configuration of a Christmas tree. Generator was operated at 150 W (frequency, 460 kHz). RF waves emanate from each tine.

View larger version (91K): [in a new window]   Figure 1b. (a) HiTT 106 perfusion electrode has micropores in needle tip for saline infusion. Digitally controlled syringe pump was connected to 60-W RF generator (frequency, 375 kHz) to provide continuous saline flow through micropores into surrounding tissue during ablation. (b) Cool Tip (internally cooled cluster) electrode was connected to new generation of 250-W RF generators (frequency, 480 kHz). Shafts of three internally cooled probes spaced 5 mm apart are electrically insulated with 2.5 cm of exposed active tip. Acrylic guide maintains correct interprobe distance. (c) RF 3000 (expandable 12-tine) electrode with curved tines fully deployed in configuration of an umbrella. Alternating electric-current generator was operated at 200 W (frequency, 480 kHz). RF waves emanate from each tine. (d) Model 1500 electrode (expandable nine-tine) electrode with curved tines fully deployed in configuration of a Christmas tree. Generator was operated at 150 W (frequency, 460 kHz). RF waves emanate from each tine.

View larger version (91K): [in a new window]   Figure 1c. (a) HiTT 106 perfusion electrode has micropores in needle tip for saline infusion. Digitally controlled syringe pump was connected to 60-W RF generator (frequency, 375 kHz) to provide continuous saline flow through micropores into surrounding tissue during ablation. (b) Cool Tip (internally cooled cluster) electrode was connected to new generation of 250-W RF generators (frequency, 480 kHz). Shafts of three internally cooled probes spaced 5 mm apart are electrically insulated with 2.5 cm of exposed active tip. Acrylic guide maintains correct interprobe distance. (c) RF 3000 (expandable 12-tine) electrode with curved tines fully deployed in configuration of an umbrella. Alternating electric-current generator was operated at 200 W (frequency, 480 kHz). RF waves emanate from each tine. (d) Model 1500 electrode (expandable nine-tine) electrode with curved tines fully deployed in configuration of a Christmas tree. Generator was operated at 150 W (frequency, 460 kHz). RF waves emanate from each tine.

View larger version (106K): [in a new window]   Figure 1d. (a) HiTT 106 perfusion electrode has micropores in needle tip for saline infusion. Digitally controlled syringe pump was connected to 60-W RF generator (frequency, 375 kHz) to provide continuous saline flow through micropores into surrounding tissue during ablation. (b) Cool Tip (internally cooled cluster) electrode was connected to new generation of 250-W RF generators (frequency, 480 kHz). Shafts of three internally cooled probes spaced 5 mm apart are electrically insulated with 2.5 cm of exposed active tip. Acrylic guide maintains correct interprobe distance. (c) RF 3000 (expandable 12-tine) electrode with curved tines fully deployed in configuration of an umbrella. Alternating electric-current generator was operated at 200 W (frequency, 480 kHz). RF waves emanate from each tine. (d) Model 1500 electrode (expandable nine-tine) electrode with curved tines fully deployed in configuration of a Christmas tree. Generator was operated at 150 W (frequency, 460 kHz). RF waves emanate from each tine.

View larger version (176K): [in a new window]   Figure 2. Gross pathologic specimen from 3-mm-thick liver slice shows how extent of thermally induced coagulation was determined. White line surrounds only central white zone of coagulation and thus excludes variable rim of hyperemia. Red and green areas represent guide marks.

View larger version (136K): [in a new window]   Figure 3a. (a) HiTT 106 system. Gross pathologic specimen shows morphologic changes that surround large vessel wall (arrow) and correspond mostly to white coagulative necrosis. Induced coagulation is distant from primary coagulation zone obtained after 20-minute RF application. Yellow area represents one of the four implanted guide marks. (b) Gross pathologic specimen after immunohistochemical assay shows DNA strand breaks (arrows) surrounding vessel. Assignment of DNA damage to white or red zone of coagulation was not achieved.

View larger version (159K): [in a new window]   Figure 3b. (a) HiTT 106 system. Gross pathologic specimen shows morphologic changes that surround large vessel wall (arrow) and correspond mostly to white coagulative necrosis. Induced coagulation is distant from primary coagulation zone obtained after 20-minute RF application. Yellow area represents one of the four implanted guide marks. (b) Gross pathologic specimen after immunohistochemical assay shows DNA strand breaks (arrows) surrounding vessel. Assignment of DNA damage to white or red zone of coagulation was not achieved.

View larger version (88K): [in a new window]   Figure 4a. Three-dimensional models of thermally induced coagulation. (a) HiTT 106 system. Coagulation area obtained after 20-minute RF application has irregular extensions of tissue destruction and oval form. Yellow line simulates relationship between electrode position and ablation. Red circles correspond to additive areas of coagulation necrosis. (b) Cool Tip system. Area of coagulation obtained after 12-minute RF application. Defect at top of coagulation area is a result of heat-sink effect of a patent large vessel. Green line simulates relationship between electrode position and thermally induced lesion. (c) RF 3000 system. Electrode tines may be recognized in periphery of coagulation area. Cephalic extent of necrotic area is limited. Yellow line simulates relationship between electrode position and thermally induced lesion. Yellow circles correspond to additive small areas of coagulation necrosis. (d) Model 1500 system. Area of coagulation is less spherical than that in c. Deformations of thermally induced lesion correspond to fully deployed prongs of electrode. Green line simulates relationship between electrode position and thermally induced lesion. Green circles correspond to additive small areas of coagulation necrosis.

View larger version (69K): [in a new window]   Figure 4b. Three-dimensional models of thermally induced coagulation. (a) HiTT 106 system. Coagulation area obtained after 20-minute RF application has irregular extensions of tissue destruction and oval form. Yellow line simulates relationship between electrode position and ablation. Red circles correspond to additive areas of coagulation necrosis. (b) Cool Tip system. Area of coagulation obtained after 12-minute RF application. Defect at top of coagulation area is a result of heat-sink effect of a patent large vessel. Green line simulates relationship between electrode position and thermally induced lesion. (c) RF 3000 system. Electrode tines may be recognized in periphery of coagulation area. Cephalic extent of necrotic area is limited. Yellow line simulates relationship between electrode position and thermally induced lesion. Yellow circles correspond to additive small areas of coagulation necrosis. (d) Model 1500 system. Area of coagulation is less spherical than that in c. Deformations of thermally induced lesion correspond to fully deployed prongs of electrode. Green line simulates relationship between electrode position and thermally induced lesion. Green circles correspond to additive small areas of coagulation necrosis.

View larger version (64K): [in a new window]   Figure 4c. Three-dimensional models of thermally induced coagulation. (a) HiTT 106 system. Coagulation area obtained after 20-minute RF application has irregular extensions of tissue destruction and oval form. Yellow line simulates relationship between electrode position and ablation. Red circles correspond to additive areas of coagulation necrosis. (b) Cool Tip system. Area of coagulation obtained after 12-minute RF application. Defect at top of coagulation area is a result of heat-sink effect of a patent large vessel. Green line simulates relationship between electrode position and thermally induced lesion. (c) RF 3000 system. Electrode tines may be recognized in periphery of coagulation area. Cephalic extent of necrotic area is limited. Yellow line simulates relationship between electrode position and thermally induced lesion. Yellow circles correspond to additive small areas of coagulation necrosis. (d) Model 1500 system. Area of coagulation is less spherical than that in c. Deformations of thermally induced lesion correspond to fully deployed prongs of electrode. Green line simulates relationship between electrode position and thermally induced lesion. Green circles correspond to additive small areas of coagulation necrosis.

View larger version (55K): [in a new window]   Figure 4d. Three-dimensional models of thermally induced coagulation. (a) HiTT 106 system. Coagulation area obtained after 20-minute RF application has irregular extensions of tissue destruction and oval form. Yellow line simulates relationship between electrode position and ablation. Red circles correspond to additive areas of coagulation necrosis. (b) Cool Tip system. Area of coagulation obtained after 12-minute RF application. Defect at top of coagulation area is a result of heat-sink effect of a patent large vessel. Green line simulates relationship between electrode position and thermally induced lesion. (c) RF 3000 system. Electrode tines may be recognized in periphery of coagulation area. Cephalic extent of necrotic area is limited. Yellow line simulates relationship between electrode position and thermally induced lesion. Yellow circles correspond to additive small areas of coagulation necrosis. (d) Model 1500 system. Area of coagulation is less spherical than that in c. Deformations of thermally induced lesion correspond to fully deployed prongs of electrode. Green line simulates relationship between electrode position and thermally induced lesion. Green circles correspond to additive small areas of coagulation necrosis.