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.