Intraoperative radiofrequency ablation using a loop internally cooled-perfusion electrode: in vitro and in vivo experiments.
OBJECTIVE
We sought to validate the efficiency of intraoperative radiofrequency ablation (RFA) using a prototype loop internally cooled-perfusion (LICP) electrode to induce coagulation in the subcapsular portion of the liver.


METHODS
In in vitro experiments, 30 ablation regions were created using a 200-W generator and a LICP electrode featured simultaneous intraelectrode cooling and continuous flow of hypertonic saline along the shaft in explanted bovine liver. In the in vivo experiments, 26 ablation zones were created according to one of the five protocols in 10 dogs: group A, RFA using a cooled-tip electrode (n = 6); group B, RFA using a LICP electrode with 2 cm loop tip (n = 6); group C, RFA using a LICP electrode with a 3-cm loop tip (n = 6); group D, RFA using a cooled-tip electrode and Pringle maneuver (n = 4); and group E, RFA using a LICP electrode with 2 cm loop tip and Pringle maneuver (n = 4). The dimensions of the coagulation parameters were compared between the groups.


RESULTS
In the in vitro experiments, RFA using a 2- or 3-cm diameter LICP electrode (3.6 +/- 0.3 cm, 3.4 +/- 0.5 cm, respectively) created deeper dimensions of coagulation than did a 4-cm electrode (2.3 +/- 0.2 cm; P < 0.05). In the in vivo experiments, the RFA using the LICP electrodes in porcine liver with normal perfusion induced wider but superficial ablation regions when compared to standard RFA using an internally cooled electrode (P < 0.05). However, using a Pringle maneuver, RFA with a LICP electrode created a larger volume of ablation area when compared to RFA using an internally cooled electrode with a similar range of axial diameter along the electrode axis: 30.0 +/- 6.1 cm3 (group D) versus 68.5 +/- 14.0 cm3 (group E; P < 0.05)


CONCLUSIONS
Intraoperative RFA using the LICP electrode induced a well-defined semicircular coagulation with a 3.5-cm axial diameter in the subcapsular region of the liver. This device appears to be promising for the treatment of superficial tumors during intraoperative RFA.
Lee
Jeong Min
JM
Department of Radiology and Institute of Radiation Medicine, Seoul National University College of Medicine, Seoul, Korea; Clinical Research Institute, Seoul National University Hospital, Seoul, Korea.
Han
Joon Koo
JK
Eoh
Hong
H
Kim
Se Hyung
SH
Lee
Jae Young
JY
Lee
Min Woo
MW
Choi
Byung Ihn
BI
D000818:Animals; D017115:Catheter Ablation / Q000379:methods*; D002417:Cattle; D004285:Dogs; D004566:Electrodes; D004867:Equipment Design; D008099:Liver; D008113:Liver Neoplasms / Q000601:surgery*