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Percutaneous radiofrequency thermal ablation with hypertonic saline injection: in vivo study in a rabbit liver model.

Lee JM, Kim YK, Lee YH, Kim SW, Li CA, Kim CS - Korean J Radiol (2003 Jan-Mar)

Bottom Line: After RFA, contrast-enhanced spiral CT was performed, and in each group the maximum diameters of the thermal lesions in gross specimens were compared.All procedures were technically successful.In addition, HS instillation before RFA more effectively achieves coagulation necrosis than HS instillation before and during RFA.

View Article: PubMed Central - PubMed

Affiliation: Department of Diagnostic Radiology, Seoul National University Hospital, Korea. leejm@radcom.snu.ac.kr

ABSTRACT

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.

Materials and 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).

Conclusion: 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.

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Related in: MedlinePlus

Graphic depiction of the changes occurring in tissue impedance, RF current and power during radiofrequency ablation in the four groups. Left: In a Group A rabbit, tissue impedance increased sharply and current decreased during RF energy instillation. Middle and Right: In Group B rabbits (middle) and those of Group C (right), an abrupt increase in tissue impedance after RF energy instillation was prevented by the infusion of NaCl solution.
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Figure 1: Graphic depiction of the changes occurring in tissue impedance, RF current and power during radiofrequency ablation in the four groups. Left: In a Group A rabbit, tissue impedance increased sharply and current decreased during RF energy instillation. Middle and Right: In Group B rabbits (middle) and those of Group C (right), an abrupt increase in tissue impedance after RF energy instillation was prevented by the infusion of NaCl solution.

Mentions: Mean initial tissue impedance was 116.4Ω ± 13 in the control group and 113.6Ω ± 15 and 110.4Ω ± 20 in Groups B and C, respectively, in which it decreased to 73.2Ω ± 5 and 68.5Ω ± 13.6, respectively, after saturated saline instillation (Table 1). This difference in impedance value before and after HS instillation was statistically significant (p < .05). Without HS instillation (Group A), impedance rose to 200-350Ω within (mean) 58 ± 8.5 seconds of application of RF energy, inducing significantly decreased current flow (less than 250 ± 105 mA) during the procedure (Fig. 1). In group B, impedance decreased with instillation of 1 mL of the solution, but approximately 90 seconds later an increase of 100-250Ω was apparent. With 0.5 mL of HS instillation prior to RFA and an additional 0.5 mL during RFA (Group C), the initial impedance decrease was maintained during RF application.


Percutaneous radiofrequency thermal ablation with hypertonic saline injection: in vivo study in a rabbit liver model.

Lee JM, Kim YK, Lee YH, Kim SW, Li CA, Kim CS - Korean J Radiol (2003 Jan-Mar)

Graphic depiction of the changes occurring in tissue impedance, RF current and power during radiofrequency ablation in the four groups. Left: In a Group A rabbit, tissue impedance increased sharply and current decreased during RF energy instillation. Middle and Right: In Group B rabbits (middle) and those of Group C (right), an abrupt increase in tissue impedance after RF energy instillation was prevented by the infusion of NaCl solution.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2698055&req=5

Figure 1: Graphic depiction of the changes occurring in tissue impedance, RF current and power during radiofrequency ablation in the four groups. Left: In a Group A rabbit, tissue impedance increased sharply and current decreased during RF energy instillation. Middle and Right: In Group B rabbits (middle) and those of Group C (right), an abrupt increase in tissue impedance after RF energy instillation was prevented by the infusion of NaCl solution.
Mentions: Mean initial tissue impedance was 116.4Ω ± 13 in the control group and 113.6Ω ± 15 and 110.4Ω ± 20 in Groups B and C, respectively, in which it decreased to 73.2Ω ± 5 and 68.5Ω ± 13.6, respectively, after saturated saline instillation (Table 1). This difference in impedance value before and after HS instillation was statistically significant (p < .05). Without HS instillation (Group A), impedance rose to 200-350Ω within (mean) 58 ± 8.5 seconds of application of RF energy, inducing significantly decreased current flow (less than 250 ± 105 mA) during the procedure (Fig. 1). In group B, impedance decreased with instillation of 1 mL of the solution, but approximately 90 seconds later an increase of 100-250Ω was apparent. With 0.5 mL of HS instillation prior to RFA and an additional 0.5 mL during RFA (Group C), the initial impedance decrease was maintained during RF application.

Bottom Line: After RFA, contrast-enhanced spiral CT was performed, and in each group the maximum diameters of the thermal lesions in gross specimens were compared.All procedures were technically successful.In addition, HS instillation before RFA more effectively achieves coagulation necrosis than HS instillation before and during RFA.

View Article: PubMed Central - PubMed

Affiliation: Department of Diagnostic Radiology, Seoul National University Hospital, Korea. leejm@radcom.snu.ac.kr

ABSTRACT

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.

Materials and 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).

Conclusion: 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.

Show MeSH
Related in: MedlinePlus