Percutaneous radiofrequency thermal ablation with hypertonic saline injection: in vivo study in a rabbit liver model.
OBJECTIVE
To determine whether hypertonic saline (HS, 36% NaCl) injection prior to or during radiofrequency ablation (RFA) can increase the extent of thermally mediated coagulation in in-vivo rabbit liver tissue, and also to establish the ideal injection time in relation to RFA in order to maximize its effect on the extent of radiofrequency (RF)-induced coagulation.


METHODS
In 26 rabbits, 43 RFA lesions were produced using a 17-gauge internally cooled electrode with a 1-cm active tip under ultrasound (US) guidance. Rabbits were assigned to one of three groups: Group A: RFA alone (n=8); Group B: RFA after the instillation of 1 mL HS (n=8); Group C: RFA after and during the instillation of 0.5 mL HS (n=10). RF energy (30 W) was applied for 3 minutes, and changes occurring in tissue impedance, current, power output, and the temperature of the electrode tip were automatically measured. After RFA, contrast-enhanced spiral CT was performed, and in each group the maximum diameters of the thermal lesions in gross specimens were compared. Technical success and the complications arising were evaluated by CT and on the basis of autopsy findings.


RESULTS
All procedures were technically successful. There were six procedure-related complications (6/26; 23%), including five localized perihepatic hematomas and one thermal injury to the stomach. With instillation of HS in group B rabbits, markedly decreased tissue impedance (73 Omega+/-5) and increased current (704 mA+/-41) were noted, compared to RF ablation without saline infusion (116.3 Omega+/-13, 308 mA+/-80). With instillation of the solution before RFA (group B), coagulation necrosis was greater (14.9 mm+/- 3.8) than in rabbits not injected (group A: 11.5 mm+/-2.4; Group A vs. B: p <.05) and in those injected before and during RFA (group C: 12.5 mm+/-3.1; Group B vs. C: p >.05).


CONCLUSIONS
RFA using HS instillation can increase the volume of RFAinduced necrosis of the liver with a single application, thereby simplifying and accelerating the treatment of larger lesions. In addition, HS instillation before RFA more effectively achieves coagulation necrosis than HS instillation before and during RFA.
Lee
Jeong Min
JM
Department of Diagnostic Radiology, Seoul National University Hospital, Korea. leejm@radcom.snu.ac.kr
Kim
Young Kon
YK
Lee
Young Hwan
YH
Kim
Sang Won
SW
Li
Chun Ai
CA
Kim
Chong Soo
CS
D000818:Animals; D017115:Catheter Ablation; D005240:Feasibility Studies; D008099:Liver / Q000473:pathology / Q000601:surgery*; D008297:Male; D009336:Necrosis; D011817:Rabbits; D012449:Safety; D012462:Saline Solution, Hypertonic / Q000008:administration & dosage / Q000494:pharmacology*; D014057:Tomography, X-Ray Computed
D012462:Saline Solution, Hypertonic