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Background: Radiofrequency ablation (RFA) and electrochemical treatment (ECT) are two methods of local liver tumour ablation. The objective of this study was to compare these methods when applied in proximity to vessels in vivo., Methods: In a total of ten laparotomised pigs, we used ECT (Group A, four animals) and RFA (Group B, four animals) to create four areas of ablation per animal under ultrasound guidance within 10 mm of a vessel. Group C consisted of two control animals. Chemical laboratory tests were performed immediately before and after each procedure and on days 1, 3 and 7 after surgery. Following the last tests, the livers were harvested for morphological evaluation., Results: The mean duration of surgery was 5 h 40 min in Group A (ECT), 2 h 47 min in Group B (RFA), and 2 h 30 min in Group C (control animals). After ECT, the harvested livers showed a mean volume of necrosis of 1.84 cm(3) ± 0.88 at the anode and 2.59 cm(3) ± 1.06 at the cathode. The presence of vessels did not influence the formation of necrotic zones. Ablation time was 67 min when a charge of 200 coulombs was delivered. We measured pH values of 1.2 (range: 0.9-1.7) at the anode and 11.7 (range: 11.0-12.1) at the cathode. In one of the 16 RFA ablations (6%), the target temperature was not reached and the procedure was discontinued. After 14 of 16 RFA procedures (88%), morphological analysis showed incomplete ablation in perivascular sites. Both ECT and RFA were associated with a reversible increase in monocyte, C-reactive protein (CRP) and aspartate aminotransferase (AST) levels. There was no significant increase in interleukin-1β (IL-1β), tumour necrosis factor-α (TNF-α) and IL-6., Conclusion: In the majority of cases, intrahepatic RFA in vivo leads to incomplete necrosis in proximity to vessels and the presence of histologically intact perivascular cells. Without a reduction in liver perfusion, the central application of RFA should be considered problematic. ECT is a safe alternative. It is not associated with a heat sink effect but has the disadvantage of long treatment times., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

Background: Radiofrequency ablation (RFA) and electrochemical treatment (ECT) are two methods of local liver tumor ablation. A reproducible perfusion model allowed us to compare these methods when applied in proximity to vascular structures., Material and Methods: In a porcine liver perfusion model, we used RFA (group A) and ECT (group B) to perform ablations under ultrasound guidance within 10 mm of a vessel and examined the induced necrosis macroscopically and histologically., Results: We created 83 lesions (RFA: 59, ECT: 24) in 27 livers. In group A (mean liver weight: 2046 g), perfusion was macroscopically found to limit necrosis in 52.5% of the procedures. Histology demonstrated the destruction of only 30.4% of the vessel walls within the ablation areas. In group B (mean liver weight: 1885 g), we detected reproducible and sharply demarcated ablation areas both macroscopically and histologically. Necrosis was unaffected by nearby vessels. No viable cells were found perivascularly. Histology showed destruction of the vascular endothelium without any discontinuities. We measured pH values of 0.9 (range: 0.6-1.8) at the anode and 12.2 (range: 11.4-12.6) at the cathode. Treatment time was 100 min when a charge of 300 coulombs was delivered., Conclusions: Electrochemical treatment is a method of ablation that creates reproducible and predictable volumes of necrosis. It produces sharply demarcated areas of complete necrosis also in perivascular sites. ECT, however, requires much longer treatment times than RFA. In our model, the effects of RFA were considerably limited by perfusion, which caused incomplete areas of necrosis in proximity to vessels., (Copyright © 2012 Elsevier Inc. All rights reserved.)

Background: Laparoscopic radiofrequency ablation (RFA) is a safe and effective method for tumor destruction in patients with unresectable liver tumors. However, accurate probe placement using laparoscopic ultrasound guidance is required to achieve complete tumor ablation. This study aimed to develop a perfusable ex vivo tumor-mimic model for laparoscopic radiofrequency ablation training., Methods: After rinsing the prepared liver vessels with anticoagulants, porcine livers were perfused. Tumor-mimics were created by injecting a mixture consisting of 3% agarose, 3% cellulose, 7% glycerol, and 0.05% methylene blue, creating hyperechoic lesions in ultrasound. Heparinized porcine blood was used as perfusion medium. Continuous perfusion of the porcine liver was provided by connection of a pump system to the portal vein and the vena cava inferior. Laparoscopic RFA techniques were taught using a laparoscopic pelvi-trainer., Results: A total of 30 laparoscopic ablations were performed in four porcine livers. The simulated "tumors" were clearly visible on laparoscopic ultrasound and not felt during placement of the RFA probe. In addition, color duplex ultrasound showed clear signals indicating for a sufficient liver perfusion., Conclusion: Laparoscopic RFA requires advanced laparoscopic ultrasound skills for an accurate placement of the RFA probe. The perfused tumor-mimic model presented is a safe, easy, effective, and economic method to improve and train laparoscopic RFA skills on porcine liver tissue.

Background/aims: Radiofrequency-ablation (RFA) is an effective therapeutic option for destruction of irresectable primary and secondary liver tumors and has been successfully performed transcutaneously using sonographic or computer tomographic guidance or by laparotomy. The laparoscopic approach combines a minimal invasiveness with optimal diagnosis., Methodology: Between 02/2003 and 10/2005, 14 patients with a total of 45 unresectable liver tumors were treated with laparoscopic radiofrequency-ablation in our hospital. Laparoscopic RFA was primarily performed in patients' superficial lesions adjacent to neighboring organs that could be displaced by laparoscopic maneuvers, deep-sited lesions with a very difficult or impossible percutaneous approach and in combination with other laparoscopic operations., Results: All intrahepatic tumors could be detected safely by laparoscopic intraoperative ultrasound. Additional liver lesions were identified in 5 (35.7%) of the 14 patients. All 45 tumors of the 14 patients were able to be completely ablated. Laparoscopic RFA yielded no mortality and only one case of postoperative bleeding. During a mean follow-up period of 23.2 months one patient locally recurred, three patients had new malignant nodules and two patients died with disease., Conclusions: Laparoscopic RFA is safe and provides a minimally invasive procedure with the option of simultaneous inflow-occlusion during thermoablation. Even more, neighboring organs can be protected, simultaneous resections can be performed and intraoperative ultrasound is used to gain further diagnosis.

Purpose: Laparoscopic radiofrequency ablation is safe, practicable, and combines minimally invasive surgery with the advantages of laparotomy. However, application of the laparoscopic freehand puncture is restricted because of capnoperitoneum and the consequent fixation of the needle on two different points. The use of a laparoscopic ultrasound probe with a canal for puncture can solve this problem and improve precision. However, a stiff needle limits the necessary angulation that is needed to reach right-lateral and cranial liver metastases. Therefore we present a new navigation tool for laparoscopic interventions., Materials and Methods: The US Guide 2000 (Ultra Guide, Tirat Hacarmel, Israel) is an independent navigation system compatible with all ultrasound machines and has six degrees of freedom. After proper evaluation of this system under operating room conditions during transcutaneous radiofrequency ablation, we used this technique in laparoscopic radiofrequency ablation. A special adapter was developed to attach the ultrasound-based navigation system to a laparoscopic ultrasound probe. After calibrating the system with an ultrasound phantom, laparoscopic navigation in a liver organ model was studied., Results: Even in cases of angulation of the ultrasound probe no disturbances of the navigation system could be detected. Anatomic landmarks in the liver could be safely reached. No interaction between the navigation system and the laparoscopic ultrasound probe or operating instruments was observed., Conclusion: Our preliminary results show the feasibility of this technique in laparoscopic radiofrequency ablation. The use of an ultrasound-based laparoscopic inline navigation system offers the possibility of out-of-plane needle placement and could combine the flexibility of freehand puncture with the accuracy of a canal for puncture. This could increase the safety and accuracy of punctures.

Background and Aims: Radiofrequency-ablation (RFA) is increasingly used for destruction of unresectable primary and secondary liver tumors. We report our experience in the use of RFA for the management of unresectable hepatic malignancies., Patients and Methods: Between February 2000 and December 2004 we have undertaken 120 RFA procedures to ablate 426 unresectable primary or metastatic liver tumors in 88 patients. RFA was performed via laparotomy (n=68), laparoscopy (n=9) or a percutaneous approach (n=43). Primary liver cancer was treated in seven patients (8%) and metastatic liver tumors were treated in 81 patients (92%). All patients were followed to assess complications, treatment response and recurrence of malignant disease., Results: Procedure-related complication rate was low (3.4%). During a mean follow-up of 21.2 months, 15 patients had local tumor progression (17%), 21 patients (23.9%) had new malignant disease and 27 patients (30.7%) died from intervention-unrelated complications of their malignant disease. Additional liver lesions were identified in 27 (35%) of 77 cases by intraoperative ultrasound. Thirty-six patients received simultaneous resection and RFA., Conclusion: RFA is a safe, well-tolerated and effective treatment for patients with unresectable primary and secondary liver malignancies.

Background/Aim: Ablative techniques such as radiofrequency ablation or non-thermal electrochemical treatment (ECT) are used to manage unresectable liver metastases. Although ECT is not affected by the cooling effect from adjacent vessels, there is a paucity of data available on ECT. Materials and Methods: We used porcine livers to establish an organ model with portal venous and hepatic arterial blood flow for a standardized analysis of the relationship between dose (electric charge) and response (volume of necrosis). Results: This model allowed us to study pressure-controlled perfusion of portal venous and hepatic arterial circulation in the absence of a capillary leak. A specially designed guiding template helped us place platinum electrodes at reproducible locations. With two electrodes, there was a linear relationship between charges of no more than 200 C and necrosis. The relationship was logarithmic at charges of 400-600 C. Larger electrode spacing led to a significant increase in necrosis. We measured pH values of 0.9 (range: 0.6-1.3) at the anode and 12.6 (range: 11.6-13.4) at the cathode. Conclusions: Using a perfusion model, we established an experimental design that allowed us to study ECT in the liver of large animals without experiments on living animals. An electrode template helped us improve the standardized analysis of dose-response relationships. ECT created reproducible and sharply demarcated areas of necrosis, the size of which depended on the charge delivered as well as on the number and spacing of electrodes. Doses higher than 600 C require longer treatment times but do not increase the area of necrosis (logarithmic dose-response relationship). [ABSTRACT FROM AUTHOR]

Background. Laparoscopic radiofrequency ablation (RFA) is a safe and effective method for tumor destruction in patients with unresectable liver tumors. However, accurate probe placement using laparoscopic ultrasound guidance is required to achieve complete tumor ablation. After evaluation of an ultrasound navigation system for transcutaneous and open RFA, we now intend to tranfer this technique to laparoscopic liver surgery. This study aimed to evaluate an electromagnetic navigation system for laparoscopic interventions using a perfusable ex vivo artificial tumor model. Materials and methods. First a special adapter was developed to attach the ultrasound and electromagnetic tracking-based navigation system to a laparoscopic ultrasound probe. The laparoscopic online navigation system was studied in a laparoscopic artificial tumor model using perfused porcine livers. Artificial tumors were created by injection of a mixture of 3% agarose, 3% cellulose, and 7% glycerol, creating hyperechoic lesions in ultrasound. Results. This study showed that laparoscopic ultrasound-guided navigation is technically feasible. Even in cases of angulation of the ultrasound probe no disturbances of the navigation system could be detected. Artificial tumors were clearly visible on laparoscopic ultrasound and not felt during placement of the RFA probe. Anatomic landmarks and simulated 'tumors' in the liver could be reached safely. Discussion. Laparoscopic RFA requires advanced laparoscopic ultrasound skills for accurate placement of the RFA probe. The use of an ultrasound-based, laparoscopic online navigation system offers the possibility of out-of-plane needle placement and could increase the safety and accuracy of punctures. The perfused artificial tumor model presented a realistic model for the evaluation of this new technique. [ABSTRACT FROM AUTHOR]