Evaluation of radiofrequency ablation using the 1-Fr wire electrode in the porcine pancreas, liver, gallbladder, spleen, kidney, stomach, and lymph nodes: A pilot study

Impact of endoscopic ultrasound-guided radiofrequency ablation in managing pancreatic malignancy

Pancreatic malignancy is still the most lethal gastrointestinal malignancy. It has a very poor prognosis with low survival rate. Surgery is still the main treatment option for pancreatic malignancy. Most patients already have locally advanced and even late stage disease due to non-specific abdominal symptoms. Even though some cases are still suitable for surgical treatment, due to its aggressiveness adjuvant chemotherapy is becoming the standard treatment for controlling the disease. Radiofrequency ablation (RFA) is a thermal therapy that has been used as one of the standard treatments for liver malignancy. It can also be performed intraoperatively. There are several reports on percutaneous RFA treatment for pancreatic malignancy using transabdominal ultrasound and guided by computed tomography scan. However, due to its anatomical location and the risk of high radiation exposure, these methods seem to be very limited. Endoscopic ultrasound (EUS) has been widely used for pancreatic abnormality evaluation due to its ability to detect more accurately, especially small pancreatic lesions, compared to other imaging modalities. By the EUS approach, it is easier to achieve good visualization of tumor ablation and necrosis as the echoendoscope position is closer to the tumor area. Based on studies and a recent meta-analysis, EUS-guided RFA is a promising treatment approach for most pancreatic malignancy cases, but most studies only collected data from a small sample size. Larger studies are needed before clinical recommendations can be made.

Endoscopic radiofrequency ablation for malignant biliary obstruction

Cholangiocarcinoma and pancreatic cancer are the most common causes of malignant biliary obstruction. The majority of patients are diagnosed at a late stage when surgical resection is rarely possible. In these cases, palliative chemotherapy and radiotherapy provide only limited benefit and are associated with poor survival. Radiofrequency ablation (RFA) is a procedure for locoregional control of tumours, whereby a high-frequency alternating current turned into thermal energy causes coagulative necrosis of the tissue surrounding the catheter. The subsequent release of debris and tumour antigens by necrotic cells can stimulate local and systemic immunity. The development of endoluminal RFA catheters has led to the emergence of endoscopically delivered RFA, a treatment mainly used for malignant biliary strictures to prolong survival and/or stent patency. Other indications include recanalisation of occluded biliary stents and treatment of intraductal ampullary adenoma or benign biliary strictures. This article presents a comprehensive review of endobiliary RFA, mainly focusing on its use in patients with malignant biliary obstruction. The available data suggest that biliary RFA may be a promising modality, having positive impacts on survival and stent patency and boasting a reasonable safety profile. However, further studies with better characterised and stratified patient populations are needed before the method becomes accepted within routine clinical practice.

The Role of Interventional Endoscopic Ultrasound in Liver Diseases: What Have We Learnt?

Chronic liver disease (CLD) is still a major problem, where the disease progression will lead to liver cirrhosis (LC) or hepatocellular carcinoma (HCC). Portal hypertension (PH) management and loco-regional therapy for HCC have become the cornerstones in advanced liver disease management. Recently, there are studies looking at the potential role of interventional endoscopic ultrasound (EUS) in liver diseases. EUS may be useful in vascular changes of the digestive wall evaluation, performing dynamic assessment of hemodynamic changes, predicting variceal bleeding and rebleeding risk, and assessing the pharmacological effects. In PH management, EUS-guided vascular therapy-which revolves around glue injection, endovascular coil placement/embolization, and combination of both-has shown promising results. As a diagnostic modality for liver cancer, the implementation of EUS in liver diseases is currently not only limited to liver biopsy (EUS-LB) but also in shear-wave elastography (SWE) and portal pressure gradient measurement, as well as portal vein sampling. The application of EUS-guided radiofrequency ablation (EUS-RFA) and tumor injection can also overcome the limitations shown by both modalities without EUS. Nevertheless, establishing EUS as a firm diagnostic and therapeutic modality is still challenging since the performance of interventional EUS requires high expertise and adequate facilities.

Endoscopic ultrasound guided hepatic interventions

Intervention for liver disease has predominantly been performed through the percutaneous approach. However, as endoscopic ultrasound (EUS) applications have expanded, there have emerged various EUS-guided interventions for liver disease, a space we call "Endo-Hepatology". EUS-guided liver biopsy can be considered the "forerunner" of Endo-Hepatology and has become a clinical option for patients requiring histologic diagnosis and staging of their liver disease. EUS also enables direct access to the portal vein. Subsequently, many procedures are being explored, such as angiography, measurement of the portosystemic pressure gradient, portal vein sampling to detect cancer cell or DNA, and EUS-guided transhepatic intrahepatic portosystemic shunt creation. Since the transducer is close to the liver, especially the left and caudate lobes, EUS can be used as a rescue when the percutaneous approach is not favorable and EUS-guided treatments of liver tumor, cyst and abscess have been reported. This review summarizes the available studies of EUS-guided intervention in the liver.

The role of EUS in diagnosis and treatment of liver disorders

Background and aim  Transabdominal ultrasound (US), computed tomographic scanning (CT) and magnetic resonance imaging (MRI) are established diagnostic tools for liver diseases. Percutaneous transhepatic cholangiography is used to perform hepatic interventional procedures including biopsy, biliary drainage procedures, and radiofrequency ablation. Despite their widespread use, these techniques have limitations. Endoscopic ultrasound (EUS), a tool that has proven useful for evaluating the mediastinum, esophagus, stomach, pancreas, and biliary tract, has an expanding role in the field of hepatology complementing the traditional investigational modalities. This review aimed to assess the current scientific evidence regarding diagnostic and therapeutic applications of EUS for hepatic diseases.

EUS-guided pancreatic radiofrequency ablation: preclinical comparison of two currently available devices in a pig model

Introduction  Two devices are currently available to perform pancreatic radiofrequency ablation (P-RFA). Potential clinical indications might extend from the treatment of pancreatic cystic lesions to ablation of small pancreatic solid lesions or cytoreduction of advanced pancreatic adenocarcinomas, but more preclinical data from animal models are needed to optimize P-RFA operation. Methods  P-RFA was performed under laparotomy and under endoscopic ultrasonographic guidance on the liver and pancreatic parenchyma of four live swine using the Habib EUS RFA (EMcision Ltd, London, UK) probe and the EUS-RA needle (Taewoong Medical, Gyeonggi-do, South Korea). Animals were sacrificed 2 hours after the procedure. Influence of tuning ablation time and power on tissue ablation were studied by histopathological assessment of the maximal depth of tissue damage on representative slides for each P-RFA shot. Results  The Habib probe in the liver parenchyma resulted in tissue necrosis increasing within the range of 1.9 ± 0.5 mm (Power = 8 W, Time = 120 s) to 2.5 ± 1 mm (Power = 10 W, Time = 120 s). In the pancreatic parenchyma, tissue damage ranged from 3.1 ± 0.4 mm (Power = 8 W, Time = 120 s) to 2.3 ± 0.1 mm (12 W, 120 s) in depth. EUS RFA ablation of the liver parenchyma resulted in tissue damage ranging from 1.6 ± 0.2 mm (Power = 30 W, Time = 11 s) to 1.5 ± 0.1 mm (Power = 70 W, Time = 9 s); in the pancreas, ablation depth ranged from 3.6 ± 0.5 mm (Power = 30 W, Time = 15 s) to 3.8 ± 0.4 mm (Power = 70 W, Time = 11 s). Conclusion  Both devices allow for effective ablation of pancreatic tissue within 1.5 to 3.8 mm around the RFA electrode, with a modest influence of tuning power settings. Specific settings are recommended for each of the devices studied. Ablation of larger lesions may require more repeat P-RFA shots in different locations rather than a simple modulation of ablation parameters.

New Indications for Endoscopic Radiofrequency Ablation

Radiofrequency ablation (RFA) is a well-established treatment for several benign, premalignant, and malignant disorders. Although the role of RFA has been clearly defined, new indications for luminal and extraluminal applications of endoscopic RFA-directed therapies have emerged. RFA has recently produced promising results in patients with a variety of gastrointestinal and hepatopancreatobiliary pathologies. For example, endoscopic RFA has been used to treat patients with gastric antral vascular ectasia, chronic radiation proctitis, malignant biliary strictures, and ampullary adenomas with intraductal extension. Furthermore, endoscopic ultrasound-guided RFA appears to be an effective, minimally invasive treatment for ablation of solid and cystic lesions-particularly in the pancreas. We review the newer indications for RFA and discuss potential limitations of endoscopic RFA.

Evaluation of Effects of Radiofrequency Ablation of Ex vivo Liver Using the 1-Fr Wire Electrode

BACKGROUND AND STUDY AIMS

Percutaneous and intraoperative radiofrequency ablation (RFA) has become a valued tool in the management of primary and secondary hepatic lesions. A recent FDA-approved endoscopic ultrasound (EUS)-guided RFA probe now offers promise to help manage such lesions. However, there are no data to determine the ideal power setting and duration of ablation needed to effectively treat hepatic masses. The aim of the study was to evaluate the macroscopic zone of hepatic injury for EUS-RFA using a variety of settings within a fresh porcine hepatic specimen.

METHODS

RFA was performed using the Habib EUS-RFA needle (EMcision Ltd, London, UK) which is a 1-Fr wire (0.33 mm, 0.013 inch) with a working length of 190 cm. A step by step approach to deliver radiofrequency energy at 5, 10, 15, 20, and 50 W of power and 10, 30, 60, 90, 120, and 300 seconds, respectively, was followed. Macroscopic and microscopic findings of the ablation zone were evaluated at each setting.

RESULTS

The maximal zone (diameter, 8.2±0.14 mm; length, 20.85±0.21 mm) of coagulative necrosis was achieved using an ablation power of 10 W for duration of 90 seconds. Notably, increased power settings resulted in an unexpected and diminished effect on tissue destruction.

CONCLUSIONS

Our findings support the use of 10 W power for 90 seconds for maximum ablation in the liver. Our data also provide initial guidance and alternate settings to be considered when performing EUS-RFA to adjust the ablation power and duration to match the lesion size, shape, and risk of injury to adjacent structures.

Endoscopic Radiofrequency Ablation of the Pancreas

Radiofrequency ablation (RFA) is a well-established technique to ablate dysplastic and neoplastic tissue via local thermal coagulative necrosis. Despite the widespread use in management of several cancers, the application of RFA in pancreas has been limited due to the increased risks of complications from the increased sensitivity of pancreatic tissue to thermal injury and proximity to vascular and biliary structures. RFA has been successfully used during laparotomy for locally advanced pancreatic carcinoma but requires an invasive approach. Endoscopic ultrasound-guided RFA offers the best combination of excellent visualization, real-time imaging guidance, and precise localization with minimal invasiveness. Several animal and human studies have demonstrated the technical feasibility and safety of endoscopic RFA in the pancreas. This article provides a comprehensive review of endoscopic RFA in the management of pancreatic lesions.