Percutaneous microwave coagulation therapy using artificial ascites

Thermal ablation for hepatic tumors in high-risk locations

Thermal ablative techniques such as radiofrequency and microwave ablation are minimally invasive and cost-effective approaches that are currently being adopted as alternatives to surgical resection for primary and metastatic liver malignancies. However, they are considered to be relatively contraindicated for tumors in high-risk locations due to technical difficulties and a perceived increased risk of perioperative complications. Several techniques, including artificial ascites, non-touch multibipolar ablation, and laparoscopically assisted ablation, can be used to improve the outcomes of ablation for high-risk tumors. This review aims to provide a comprehensive summary of the techniques currently used to improve thermal ablation outcomes for high-risk liver tumors.

Successful surgical rescue of delayed onset diaphragmatic hernia following radiofrequency ablation using a thoracoscopic approach for hepatocellular carcinoma: a case report

Background

Radiofrequency ablation (RFA) is widely used as a minimally invasive treatment for hepatocellular carcinoma (HCC). RFA has a low risk of complications, especially compared with liver resection. Nevertheless, various complications have been reported after RFA for HCC; however, diaphragmatic hernia (DH) is extremely rare.

Case presentation

A 78-year-old man underwent thoracoscopic RFA for HCC located at the medial segment adjacent to the diaphragm approximately 7 years before being transported to the emergency department due complaints of nausea and abdominal pain. Computed tomography revealed a prolapsed small intestine through a defect in the right diaphragm, and emergency surgery was performed. The cause of diaphragmatic hernia was the scar of RFA. We confirmed that the small intestine had prolapsed into the right diaphragm, and we resected the necrotic small intestine and repaired the right diaphragm. Herein, we report a case of ileal strangulation due to diaphragmatic hernia after thoracoscopic RFA.

Conclusions

Care should be taken when performing thoracoscopic RFA, especially for tumors located on the liver surface adjacent to the diaphragm. Patients should be carefully followed up for possible DH, even after a long postoperative interval.

Radiofrequency ablation for hepatocellular carcinoma abutting the diaphragm: the value of artificial ascites

Ultrasound (US)-guided percutanoeus radiofrequency (RF) ablation is difficult to perform for treating a hepatic tumor abutting the diaphragm due to a poor sonic window and high risk of diaphragmatic thermal injury. RF ablation with assistance of the use of artificial ascites is a simple and safe technique for treating a hepatic dome tumor abutting the diaphragm. One can improve the sonic window and separate the RF ablation zone from the diaphragm by downward displacement of the liver with the use of a simple and inexpensive technique. Dextrose water solution is an ideal fluid due to its nonionic nature. Complications related to the use of artificial ascites including hemoperitoneum are rare. Peritoneal adhesion and tumor location in the bare area are the limitations for the application of this technique.

Percutaneous radiofrequency ablation of hepatocellular carcinoma abutting the diaphragm and gastrointestinal tracts with the use of artificial ascites: safety and technical efficacy in 143 patients

The purpose of this study was to assess the feasibility, safety and efficacy of radiofrequency ablation (RFA) with the use of artificial ascites for hepatocellular carcinoma (HCC) adjacent to the diaphragm and gastrointestinal tract. One hundred forty-three patients with 181 HCCs who underwent US-guided percutaneous RFA with the use of artificial ascites were retrospectively reviewed. Among the 181 HCCs, 148 HCCs were defined as problematic nodules for two major reasons: poor sonic window or possible thermal injury. We artificially induced ascites before performing RFA by dripping 5% dextrose in a water solution. We assessed the technical success of introducing artificial ascites, technical feasibility of the use of artificial ascites and complications. The technical success rate, as well as the primary and secondary technique success rate, was assessed by regular follow-up CT examinations. RFA with artificial ascites was successfully achieved in 130 of 143 patients. The primary technique effectiveness was 85.3%. During follow-up (mean, 20.4 months), remote intrahepatic recurrence occurred in 49 patients and local tumor progression occurred in 15 patients. Three (2.1%) of the 143 patients experienced major complications (hemoperitoneum, lobar infarction and biloma) related to the RFA procedure. The use of artificial ascites is a simple and useful technique to minimize collateral thermal injury and to improve the sonic window.

Does artificial ascites induce the heat-sink phenomenon during percutaneous radiofrequency ablation of the hepatic subcapsular area?: an in vivo experimental study using a rabbit model

OBJECTIVE

To evaluate the effect of the heat-sink phenomenon induced by artificial ascites on the size of the ablation zone during percutaneous radiofrequency (RF) ablation of the hepatic subcapsular area in an in vivo rabbit model.

MATERIALS AND METHODS

A total of 21 percutaneous rabbit liver RF ablations were performed with and without artificial ascites (5% dextrose aqueous solution). The rabbits were divided into three groups: a) control group (C, n = 7); b) room temperature ascites group (R, n = 7); and c) warmed ascites group (W, n = 7). The tip of a 1 cm, internally cooled electrode was placed on the subcapsular region of the hepatic dome via ultrasound guidance, and ablation was continued for 6 min. Changes in temperature of the ascites were monitored during the ablation. The size of the ablation zones of the excised livers and immediate complications rates were compared statistically between the groups (Mann-Whitney U test, Kruskal-Wallis test, linear-by-linear association, p = 0.05).

RESULTS

One rabbit from the "W" group expired during the procedure. In all groups, the ascites temperatures approached their respective body temperatures as the ablations continued; however, a significant difference in ascites temperature was found between groups "W" and "R" throughout the procedures (39.2+/-0.4 degrees C in group W and 33.4+/-4.3 degrees C in group R at 6 min, p = 0.003). No significant difference was found between the size of the ablation zones (782.4+/-237.3 mL in group C, 1,172.0+/-468.9 mL in group R, and 1,030.6+/-665.1 mL in group W, p = 0.170) for the excised liver specimens. Diaphragmatic injury was identified in three of seven cases (42.9%) upon visual inspection of group "C" rabbits (p = 0.030).

CONCLUSION

Artificial ascites are not likely to cause a significant heat-sink phenomenon in the percutaneous RF ablation of the hepatic subcapsular region.

Radiofrequency ablation of the liver abutting stomach: in vivo comparison of gastric injury before and after intragastric saline administration in a porcine model

PURPOSE

To compare the in vivo gastric injury observed during radiofrequency (RF) ablation of the liver abutting the stomach before and after the intragastric administration of chilled saline.

MATERIALS AND METHODS

Twenty RF ablation zones were created in the livers of 10 pigs with a 1-cm-exposed active tip of an internally cooled electrode under ultrasound guidance for 10 min. Ten RF ablation zones were created before (non-saline group) and after (saline group) the intragastric administration of approximately 1000 mL of chilled saline, and 20 RF ablation zones were made in the posterior part of the left lobe abutting the stomach. The frequency and severity of the thermal injury observed in the stomach of the two groups were compared histologically.

RESULTS

All the resected gastric specimens showed thermal injuries of varying degrees of severity. The largest diameter of the gastric injury was significantly smaller in the saline group (mean 1.5 cm; range 1.3-1.8 cm) than in the non-saline group (mean 2.1cm; range 1.8-2.4 cm) (p=0.000). The saline group showed significantly less thermal injury to the muscular layer of the gastric wall by the histopathology (p=0.033).

CONCLUSIONS

The intragastric administration of chilled saline might be a useful technique for reducing the severity of gastric injury during RF ablation of the liver abutting the stomach.

Minimizing abdominal wall damage during high-intensity focused ultrasound ablation by inducing artificial ascites

High-intensity focused ultrasound (HIFU) is becoming an important tool for tumor treatment [especially hepatocellular carcinoma (HCC)] in Asian countries. A HIFU system provides unique advantages of low invasiveness and absence of nonradiation. However, if the target HCC is close to the proximal surface of the liver, HIFU may overheat diaphragm, abdominal wall or skin. To avoid this complication, a method using artificial ascites in the abdominal cavity to separate the liver from the peritoneum, and to serve as a heat sink to cool overlying structures and thereby avoid inducing permanent damage was proposed. Target tissue that was 10 mm below the liver surface was ablated in 12 New Zealand white rabbits: 6 in the experimental group and 6 in the control group. Artificial ascites was established in the experimental group by injecting normal saline into the abdominal cavity until the pressure reached 150 mm H2O. Artificial ascites not only reduced the probability and extent of thermal damage to intervening structures, but also had no adverse affect on the efficacy of HIFU ablation.

Percutaneous radiofrequency ablation of liver dome hepatocellular carcinoma invisible on ultrasonography: a new targeting strategy

Targeting of index tumours is prerequisite to their radiofrequency ablation. However, small hepatocellular carcinomas (HCCs) in the liver dome are often invisible on ultrasonography, thus causing difficulty in their targeting. In cases with multinodular HCCs, adjacent HCC lesions with compact iodized oil retention can be used as anatomic landmarks to guide radiofrequency (RF) ablation of such nodules under fluoroscopy. We present two cases in which nodules that were difficult to target with conventional methods were successfully treated by RF ablation using this targeting strategy.

CT-guided instillation of 5% dextrose in water into the anterior pararenal space before renal radiofrequency ablation in a porcine model: positive and negative effects

PURPOSE

To assess the positive and negative effects of computed tomographic (CT)-guided instillation of 5% dextrose in water (D5W) into the anterior pararenal space before renal radiofrequency (RF) ablation in a porcine model.

MATERIALS AND METHODS

Under CT guidance, D5W was instilled into the right anterior pararenal space of 10 pigs and RF ablation performed in the right kidney. For the control lesions, RF ablation was performed in the left kidney of the same pigs without pretreatment with D5W. Approximately 1 week after RF ablation, bowel adhesion to both kidneys was compared by using a 5-point scale at open laparotomy, as follows: grade 0=no adhesion, grade 1=detachable adhesion, grade 2=grade 1 adhesion plus other adhesion to organs, grade 3=undetachable adhesion, and grade 4=bowel perforation. The areas of coagulation necrosis in both kidneys were compared at pathologic examination.

RESULTS

Bowel adhesions to the right kidneys were classified as grade 0 in nine pigs and as grade 1 in one pig, whereas those to the left kidneys were classified as grade 2 in two pigs and as grade 3 in eight (P<.05). The mean areas of coagulation necrosis in right and left kidneys were 0.58 cm2+/-0.5 and 1.53 cm2+/-1.3, respectively (P<.05).

CONCLUSIONS

CT-guided D5W instillation has a positive effect in reducing the amount of bowel adhesion injury during RF ablation. However, this technique may limit the area of coagulation necrosis in a swine model. Longer term pathologic evaluation is necessary to fully understand the effects of D5W instillation.

Percutaneous ultrasound-guided radiofrequency ablation of hepatocellular carcinoma with artificially induced pleural effusion and ascites

BACKGROUND

Ultrasound-guided procedures are sometimes of limited use because the tumor is located under the diaphragm or near the surface of the liver. We investigated the safety and efficacy of radiofrequency ablation (RFA) with artificial pleural effusion and/or artificial ascites.

METHODS

Between January 2002 and May 2006, 43 lesions in 36 patients with hepatocellular carcinoma (HCC) were treated by RFA with artificial pleural effusion and/or artificial ascites.

RESULTS

Artificial pleural effusion allowed visualization of the whole tumor for 36 (83.7%) of the 43 lesions that were otherwise not detectable or poorly visible. Artificial ascites was also helpful in visualizing whole tumors that could not be visualized with only artificial pleural effusion. In all lesions, artificial pleural effusion and/or artificial ascites were helpful in performing percutaneous RFA. Artificial ascites was useful for creating a space between the liver's surface and the skin or diaphragm to avoid burns. Adverse effects after the induction of artificial pleural effusion included pneumonia in one patient and temporary atelectasis in another patient. Severe side effects were not observed. Complete necrosis after RFA was obtained in 43 (100%) of the 43 lesions. During a mean follow-up period of 31.8 +/- 5.8 months, local recurrence at the ablation site was found in none of the 43 lesions.

CONCLUSIONS

Percutaneous RFA with artificial pleural effusion and/or artificial ascites was a safe and useful treatment that resulted in good local control of HCC.

Radiofrequency ablation of the liver in a rabbit model: creation of artificial ascites to minimize collateral thermal injury to the diaphragm and stomach

PURPOSE

To assess whether the creation of artificial ascites during radiofrequency (RF) ablation of the subcapsular portion of the liver can minimize collateral thermal injury to the diaphragm and stomach.

MATERIALS AND METHODS

A total of 20 percutaneous RF ablation procedures were performed in the livers of 10 rabbits (control, n = 5; experimental, n = 5) with use of an internally cooled electrode (1-cm active tip). In the experimental group, artificial ascites was established before RF ablation by dripping 320 mL of normal saline solution via a 20-gauge sheathed needle to separate the liver from the diaphragm and stomach. In each rabbit, two subcapsular ablation zones were made in the inferior tip of the left lobe of the liver adjacent to the stomach and in the far dome of the right lobe next to the diaphragm consecutively. After the animals were killed 3 days after the procedure, the frequency, size, and degree of thermal injury were compared between the experimental and control groups. The degree of thermal injury was graded by visual inspection according to a four-point scoring system. Representative cases underwent gross and histologic analysis.

RESULTS

Artificial ascites was achieved successfully with a single puncture in all rabbits in the experimental group. Mean procedure time for the formation of artificial ascites was 9 minutes. There was no difference in the size of the RF ablation zones in the liver between the two groups (P > .05). Thermal injury in the adjacent organs was observed significantly more frequently in the control group compared with the experimental group (diaphragm, 100% vs 0; stomach, 80% vs 20%; P < .05).

CONCLUSION

Creation of artificial ascites may be a simple and useful technique that can be used to reduce the frequency and severity of thermal injury during RF ablation of subcapsular hepatic tumors.

Artificial ascites technique for percutaneous radiofrequency ablation of liver cancer adjacent to the gastrointestinal tract

Background

Percutaneous radiofrequency ablation (RFA) of liver tumours adjacent to the gastrointestinal tract is controversial. This study assessed the value of an intraperitoneal water infusion (artificial ascites) technique for percutaneous RFA of such tumours.

Methods

Before ablation in 52 patients (55 treatments, 58 tumours), between 250 and 3000 (mean 681) ml 5 per cent glucose solution was infused into the abdominal cavity using a 14-G needle, with the aim of preventing thermal injury by separating the liver from the gastrointestinal tract.

Results

There were no adverse events associated with the artificial ascites technique. In 43 (78 per cent) of the 55 treatments, the liver and gastrointestinal tract were separated successfully. In the other 12 treatments, in which the separation was not confirmed by real-time ultrasonography, there was one case of perforation of the ascending colon after RFA; adhesion of the liver and colon resulting from previous laparotomy may have been related to the injury.

Conclusion

Production of artificial ascites can be undertaken safely, making RFA safe and effective for hepatic tumours adjacent to the gastrointestinal tract. In patients with possible postoperative adhesions, confirmation of separation of the liver from surrounding organs is mandatory to avoid thermal injury.

Complications of radiofrequency coagulation of liver tumours

BACKGROUND

Radiofrequency coagulation (RFC) is being promoted as a novel technique with a low morbidity rate in the treatment of liver tumours. The purpose of this study was to assess critically the complication rates of RFC in centres with both large and limited initial experience, and to establish causes and possible means of prevention and treatment.

METHODS

This is an exhaustive review of the world literature (articles and abstracts) up to 31 December 2001; 82 independent reports of RFC of liver tumours were analysed.

RESULTS

In total, 3670 patients were treated with percutaneous, laparoscopic or open RFC. The mortality rate was 0.5 per cent. Complications occurred in 8.9 per cent: abdominal bleeding in 1.6 per cent, abdominal infection in 1.1 per cent, biliary tract damage in 1.0 per cent, liver failure in 0.8 per cent, pulmonary complications in 0.8 per cent, dispersive pad skin burn in 0.6 per cent, hepatic vascular damage in 0.6 per cent, visceral damage in 0.5 per cent, cardiac complications in 0.4 per cent, myoglobinaemia or myoglobinuria in 0.2 per cent, renal failure in 0.1 per cent, tumour seeding in 0.2 per cent, coagulopathy in 0.2 per cent, and hormonal complications in 0.1 per cent. The complication rate was 7.2, 9.5, 9.9 and 31.8 per cent after a percutaneous, laparoscopic, simple open and combined open approach respectively. The mortality rate was 0.5, 0, 0 and 4.5 per cent respectively.

CONCLUSION

The morbidity and mortality of RFC, while low, is higher than previously assumed. With adequate knowledge, many complications are preventable.