Laparoscopic ablation of liver adenoma by radiofrequency electrocauthery

Evolution and current trends in the management of colorectal cancer liver metastasis

Metastatic colorectal cancer (mCRC) is a major cause of cancer-related death, with a 5-year relative overall survival of up to 20%. The liver is the most common site of distant metastasis in colorectal cancer (CRC), with about 50% of CRC patients metastasizing to their liver over the course of their disease. Complete liver resection is the primary modality of treatment for resectable colorectal cancer liver metastasis (CRLM), with an overall 5-year survival rate of up to 58%. However, only 15% to 20% of patients with CRLM are deemed suitable for resection at presentation. For unresectable diseases, the median survival of patients remains low even with the best chemotherapy. In recent decades, the management of CRLM has continued to evolve with the expansion of resection criteria, novel targeted systemic therapies, and improved locoregional therapies. However, due to the heterogeneity of the CRC patient population, the optimal evaluation of treatment options for CRLM remains complex. Therefore, effective management requires a multidisciplinary team to help define resectability and devise a personalized treatment approach, from the initial diagnosis to the final treatment.

Direct and indirect damage zone of radiofrequency ablation in porcine lumbar vertebra

Objectives

To explore the direct and indirect heat damage zone of radiofrequency ablation (RFA) in porcine vertebrae and to verify the safety of RFA in a vascularized vertebral tumor model.

Methods

RFA was performed in the porcine lumbar vertebrae. Magnetic resonance (MR) imaging, hematoxylin and eosin (HE), and terminal deoxynucleotidyl transferase dUTP nick end labelling (TUNEL) were used to assess the extent of direct and indirect injuries after RFA. The cavity of lumbar vertebrae was made, and the adjacent muscle flap was used to fill the cavity to make a vertebrae tumor model. RFA was performed in the vascularized vertebral tumor model.

Results

T1-weighted images showed a hypointensive region in the center surrounded by a more hypointensive rim on day 0 and 14. T2-weighted images showed that RFA zone was hypointensive on day 0. On day 7, hypointensity was detected in the center surrounded by a hyperintensive rim. HE showed that the RFA zone could be clearly observed on day 14. Thin bone marrow loss areas were seen around the RFA zone, which was consistent with the hyperintensive rim on the T2-weighted images. TUNEL showed a large number of apoptotic cells in the RFA zone. During RFA in the vertebral tumor model, the temperature of all monitoring positions was less than 45 °C.

Conclusion

Using in vivo experiments, the effective zone of RFA was evaluated by MR imaging and pathology, and the direct and indirect damage range were obtained. The safety of RFA was verified by RFA in a vascularized vertebral tumor model.

Percutaneous ablation of colorectal lung metastases

Lung metastasectomy can prolong survival in patients with metastatic colorectal carcinoma. Thermal ablation offers a potential solution with similar reported survival outcomes. It has minimal effect on pulmonary function, or quality of life, can be repeated, and may be considered more acceptable to patients because of the associated shorter hospital stay and recovery. This review describes the indications, technique, reported outcomes, complications and radiologic appearances after thermal ablation of colorectal lung metastases.

Thermal ablation of stage I non-small cell lung carcinoma

Ablation options for the treatment of localized non-small cell lung carcinoma (NSCLC) include radiofrequency ablation, microwave ablation, and cryotherapy. Irreversible electroporation is a novel ablation method with the potential of application to lung tumors in risky locations. This review article describes the established and novel ablation techniques used in the treatment of localized NSCLC, including mechanism of action, indications, potential complications, clinical outcomes, postablation surveillance, and use in combination with other therapies.

Influence of blood vessel on the thermal lesion formation during radiofrequency ablation for liver tumors

PURPOSE

The major obstacles of radiofrequency ablation (RFA) heat treatments are nonuniform heating in the thermal lesion and heat sinks caused by large blood vessels during treatments which could lead to high tumor recurrence in patients. The objective of this study is to help comprehend RFA heat treatment through thermal lesion formation using computer simulation, and thus to provide helpful assistance in planning RFA.

METHODS

RFA heat treatment is a popular "minimally invasive" treatment method for both primary and metastatic liver tumors, and the heat treatment is studied by numerical calculation. A finite difference model is used to solve all partial differential equations for a simple three-dimensional cubic geometry model. Maximum tissue temperature is used as a critical index for reaching thermal lesion during RFA. Cylindrical RF cool-tip electrode is internally cooled at constant water temperature. RFA thermal lesion is studied at various impacts by single and countercurrent blood vessel(s) traversing the thermal lesion. Several factors are considered, such as location, diameter, and orientation of the blood vessel(s) to the electrode.

RESULTS

Results show the thermal lesion size decreases as the lesion blood perfusion rate increases. And, single large blood vessel which is orthogonal to RF electrode will cause less undercooled volume in the thermal lesion than one which is parallel to RF electrode. Furthermore, convective energy may easily damage parallel vessel and its surrounding normal tissues during RFA. Small blood vessels (or larger vessels with slow blood flow rate) during RFA could form "tail-like" thermal lesion formation, which could damage vessel downstream spots.

CONCLUSIONS

Studies suggested that incomplete RF tumor ablation still exists within 1 cm distance between large blood vessel and RF electrode in a liver. This could have significant impact on local tumor recurrence rates. Second, if thermally significant vessel existed inevitably within the lesion, avoiding the RF cool-tip electrode placement next to the parallel large blood vessel would have a better heat treatment during RF heating. Additionally, reduced blood flow rate could help reduce significant cooling by large blood vessel.

Can a decision-making model be justified in the management of hepatocellular adenoma?

During recent years, there was a great development in the area of hepatocellular adenomas (HCA), especially regarding the pathological subtype classification, radiological imaging and management during pregnancy. This review discusses the current knowledge about diagnosis and treatment modalities of HCA and proposes a decision-making model for HCA. A Medline search of studies relevant to epidemiology, histopathology, complications, imaging and management of HCA lesions was undertaken. References from identified articles were hand-searched for further relevant articles.

Safety and efficacy of radiofrequency ablation for hepatocellular adenoma

PURPOSE

To investigate the safety and efficacy of radiofrequency (RF) ablation for the treatment of hepatocellular adenoma (HCA).

MATERIALS AND METHODS

From 2000 to 2009, 170 patients with HCA were referred to a single tertiary hepatobiliary center. Medical records of 18 patients treated with RF ablation were retrospectively analyzed.

RESULTS

All patients were female, and the majority had a history of hormonal contraceptive use. Ten patients (56%) had multiple HCAs, with a median number of two lesions (range, one to 12) per patient. Median size of HCA at the time of RF ablation was 3.0 cm (range, 0.8-7.3 cm). A total of 45 HCAs were ablated in 32 sessions (open, n = 4; percutaneous, n = 28). RF ablation was complete after the first session in 26 HCAs (57.8%), and the majority of patients underwent multiple RF ablation sessions to fully ablate all HCAs. Major complications developed in two patients.

CONCLUSIONS

RF ablation can be used effectively in the treatment of HCA. However, multiple sessions are often required, and signs of residual adenoma might persist in some patients despite repetitive treatment. RF ablation might be especially beneficial in cases not amenable to surgery or in patients who would require major hepatic resection otherwise.

Laparoscopic ultrasound with radiofrequency ablation of hepatic tumors in cirrhotic patients

BACKGROUND

The optimal treatment for hepatocellular carcinoma (HCC) is surgical resection. However, only a small percentage of patients are operative candidates due to associated liver cirrhosis. Recent advances in laparoscopic ultrasound and laparoscopy have greatly improved the accuracy in detecting intrahepatic tumor nodules, many of which were missed by preoperative imaging modality.

OBJECTIVE

The aim of this work was for an evaluation of the safety and efficacy of laparoscopic radiofrequency ablation (RFA) guided with laparoscopic ultrasound in detecting and treatment of liver tumors in patient with liver cirrhosis.

METHODS

Seventy-two patients with liver tumors (58 HCC, 9 metastatic adencarcinoma, 2 neoendocrine metastasis, 3 other metastasis) were submitted to laparoscopic RFA under laparoscopic ultrasound guidance. Forty-four patients (61.1%) were classified Child A and 28 patients (38.9%) Child B. Patients with large tumor (>6 cm), portal vein thrombosis, or Child C class were excluded from the study.

RESULTS

Laparoscopic RFA was completed in all patients without any conversion rate. Laparoscopic ultrasound identified 19 new malignant lesions (18.4%), in comparison with the result of preoperative imaging. A total of 103 hepatic focal lesions were treated by RFA (45 patients had 1 lesion, 23 patients had 2 lesions, and 4 patients had 3 lesions). There was no mortality. Morbidity occurred in 4 patients (5.5%): 2 patients had liver abscesses, 1 patient had pleural effusion, and 1 patient had postoperative bleeding necessitating blood transfusion and surgery. After a mean follow-up of 14.3 +/- 11.6 months, a complete response with 100% necrosis was achieved in 93 of 103 lesions (90.3%). Three lesions (2.9%) showed local recurrences, 5 lesions (4.8%) showed remote recurrences, and 2 lesions (1.9%) showed both local and remote recurrences.

CONCLUSIONS

Laparoscopic RFA guided with laparoscopic ultrasound is an excellent use of existing technology in the improvement of safety and efficacy of detection and treatment of intrahepatic tumors in patients with liver cirrhosis.

Use of nanoparticles for targeted, noninvasive thermal destruction of malignant cells

Shortwave (MHz range) radiofrequency (RF) energy is nonionizing, penetrates deeply into biological tissues with no adverse side effects, and heats metallic nanoparticles efficiently. Targeted delivery of these nanoparticles to cancer cells should result in hyperthermic cytotoxicity upon exposure to a focused, noninvasive RF field. We have demonstrated that gold nanoparticles conjugated with cetuximab (C225) are quickly internalized by Panc-1 (pancreatic adenocarcinoma) and Difi (colorectal adenocarcinoma) cancer cells overexpressing epidermal growth factor receptor (EGFR). Panc-1 or Difi cells treated with naked gold nanoparticles or nonspecific IgG-conjugated gold nanoparticles demonstrated minimal intracellular uptake of gold nanoparticles by transmission electron microscopy (TEM). In contrast, there were dense concentrations of cytoplasmic vesicles containing gold nanoparticles following treatment with cetuximab-conjugated gold nanoparticles. Exposure of cells to a noninvasive RF field produced nearly 100% cytotoxicity in cells treated with the cetuximab-conjugated gold nanoparticles, but significantly lower levels of cytotoxicity in the two control groups (p < 0.00012). Treatment of a breast cancer cell line (CAMA-1) that does not express EGFR with cetuximab-conjugated gold nanoparticles produced no enhanced cytotoxicity following treatment in the RF field. Conjugation of cancer cell-directed targeting agents to gold nanoparticles may represent an effective and cancer-specific therapy to treat numerous types of human malignant disease using noninvasive RF hyperthermia.

Inoperable colorectal liver metastases: a declining entity?

BACKGROUND

Untreated colorectal liver metastases (CLMs) have a dismal prognosis. Surgery remains the gold standard of treatment, but many patients will have inoperable disease at presentation. Until recently, the outlook for such patients was bleak. The purpose of this review was to report on available options in the treatment CLMs, which would be considered unresectable by conventional evaluation.

METHODS

Inclusion criteria were articles published in English-language journals reporting on either retrospective or prospective cohorts of patients undergoing treatment for conventionally inoperable CLM. Main outcome measures were survival, resectability rates, morbidity and mortality following treatment of the patients' disease.

RESULTS

Improved chemotherapy regimes and other innovative treatments have opened up new options for such patients and may even render conventionally inoperable disease resectable. The aim of treatment should be down-staging of metastases to achieve resectability, however, other treatments such as ablation may be also be used (either alone or in conjunction with resection).

CONCLUSION

A nihilistic attitude to the patient with seemingly inoperable liver metastases should be discouraged. Discussion of such patients at multi-disciplinary meetings is essential in order to plan and monitor treatments.

Percutaneous radiofrequency ablation of hepatocellular adenoma: initial experience in 10 patients

BACKGROUND AND AIM

The purpose of this study was to assess the therapeutic efficacy and safety of percutaneous radiofrequency (RF) ablation for hepatocellular adenoma.

METHODS

We performed percutaneous RF ablation in 10 patients with pathologically proven hepatocellular adenomas. Eight patients were asymptomatic and two patients had a recurrent tumor after surgical resection. The size of the tumors was 2.25 +/- 0.76 cm (range: 1.5-4.5 cm) in the largest diameter. All ablation procedures were percutaneously performed with an internally cooled RF electrode system under ultrasound (US) guidance. We evaluated the therapeutic efficacy and safety of the procedure by clinical follow-up data with regular follow-up computed tomography (CT) for 2-35 months (mean, 17.5 months).

RESULTS

All patients well tolerated percutaneous RF ablation procedure without any incident. Contrast-enhanced CT (n = 7) or contrast-enhanced US (n = 3) obtained immediately (<24 h) after the procedure revealed complete ablation of the tumor in all cases. There was no case of local tumor progression or new recurrence during the follow-up period. We found neither procedure-related mortality nor major complication requiring specific treatment.

CONCLUSION

Percutaneous RF ablation of hepatocellular adenoma without overt complication can be a new potential alternative to close imaging follow-up or elective surgery.

A review of the general aspects of radiofrequency ablation

As an alternative to standard surgical resection for the treatment of malignant tumors, radiofrequency ablation (RFA) has rapidly evolved into the most popular minimally invasive therapy. To help readers gain the relevant background knowledge and to better understand the other reviews in this Feature Section on the clinical applications of RFA in different abdominal organs, the present report covers the general aspects of RFA. After an introduction, we present a simple definition of the energy applied during RFA, a brief historical review of its technical evolution, and an explanation of the mechanism of action of RFA. These basic discussions are substantiated with descriptions of RFA equipment including those commercially available and those under preclinical development. The size and geometry of induced lesions in relation to RFA efficacy and side effects are discussed. The unique pathophysiologic process of thermal tissue damage and the corresponding histomorphologic manifestations after RFA are detailed and cross-referenced with the findings in the current literature. The crucial role of imaging technology during and after RFA is also addressed, including some promising new developments. This report finishes with a summary of the key messages and a perspective on further technologic refinements and identifies some specific priorities.

Significant long-term survival after radiofrequency ablation of unresectable hepatocellular carcinoma in patients with cirrhosis

BACKGROUND

Radiofrequency ablation (RFA) offers an alternative treatment in some unresectable hepatocellular carcinoma (HCC) patients with disease confined to the liver. We prospectively evaluated survival rates in patients with early-stage, unresectable HCC treated with RFA.

METHODS

All patients with HCC treated with RFA between September 1, 1997, and July 31, 2002, were prospectively evaluated. Patients were treated with RFA by using a percutaneous or open intraoperative approach with ultrasound guidance and were evaluated at regular intervals to determine disease recurrence and survival.

RESULTS

A total of 194 patients (153 men [79%] and 41 women [21%]) with a median age of 66 years (range, 39-86 years) underwent RFA of 289 sonographically detectable HCC tumors. All patients were followed up for at least 12 months (median follow-up, 34.8 months). Percutaneous and open intraoperative RFA was performed in 140 (72%) and 54 (28%) patients, respectively. The median diameter of tumors treated with RFA was 3.3 cm. Disease recurred in 103 (53%) of 194 patients, including 69 (49%) of 140 patients treated percutaneously and 34 (63%) of 54 treated with open RFA (not significant). Local recurrence developed in nine patients (4.6%). Most recurrence was intrahepatic. The overall complication rate was 12%. Overall survival rates at 1, 3, and 5 years for all 194 patients were 84.5%, 68.1%, and 55.4%, respectively.

CONCLUSIONS

Treatment with RFA can produce significant long-term survival rates for cirrhotic patients with early-stage, unresectable HCC. RFA can be performed in these patients with relatively low complication rates. Confirmation of these results in randomized trials should be considered.

Radiofrequency thermal ablation of liver tumors

Radiofrequency ablation (RFA) of liver tumors was first proposed in 1990. New technologies enable us to produce liver thermal lesions of approximately 3-3.5 cm in diameter; RFA has consequently become an emerging percutaneous therapeutic option both for small hepatocellular carcinoma (HCC) and for non-resectable liver metastases, mainly from colorectal cancer. New devices (for example, triplet of cooled needles, wet needles) and combined therapies (tumor ischemia and RFA) have made it possible to treat large tumors. RFA can be carried out by a percutaneous, laparoscopic or laparotomic approach. Percutaneous RFA can be performed with local anaesthesia and mild sedation; deep sedation or general anaesthesia are also used. The guidance system is generally represented by ultrasound. CT or MR examinations are the more sensitive tests for assessing therapeutic results. The series of patients treated with RFA allow the technique to be considered as effective and safe, achieving a relatively high rate of cure in properly selected cases; it should be classified as curative/effective treatment for HCC, replacing percutaneous ethanol injection. The complication rate of RFA is low but not negligible; key elements in a strategy to minimize them are identified.

Update on minimally invasive approaches to kidney tumors

Renal tumors are being detected at increasing rates because of widespread use of modern imaging techniques such as ultrasonography and computed tomography. Typically, these tumors, many of which are discovered incidentally, tend to be small and are confined to the kidney. Advances in ablative and imaging technology have led to the application of minimally invasive therapy in the treatment of small renal tumors. Although still evolving as a cancer treatment, minimally invasive treatment potentially offers several advantages over conventional open renal surgery: shorter convalescence, improved cosmesis, reduced postoperative pain, and renal preservation. This article reviews the status and recent progress of minimally invasive approaches to renal neoplasm.

Stress response to laparoscopic liver resection

The magnitude of the systemic response is proportional to the degree of surgical trauma. Much has been reported in the literature comparing metabolic and immune responses, analgesia use, or length of hospital stay between laparoscopic and open procedures. In particular, metabolic and immune responses are represented by measuring various chemical mediators as stress responses. Laparoscopic procedures are associated with reduced operative trauma compared with open procedures, resulting in lower systemic response. As a result, laparoscopic procedures are now well accepted for both benign and malignant processes. Laparoscopic liver resection, specifically, is employed for symptomatic and some malignant tumors, following improvements in diagnostic accuracy, laparoscopic devices, and techniques. However, laparoscopic liver resection is still controversial in malignant disease because of complex anatomy, the technical difficulty of the procedure, and questionable indications. There are few reports describing the stress responses associated with laparoscopic liver resection, even though many studies reviewing stress responses have been performed recently in both humans and animal models comparing laparoscopic to conventional open surgery. Although this review examines stress response after laparoscopic liver resection in both an animal and human clinical model, further controlled randomized studies with additional investigations of immunologic parameters are needed to demonstrate the consequences of either minimally invasive surgery or open procedures on perioperative or postoperative stress responses for laparoscopic liver resection.

Theoretical analysis of the heat convection coefficient in large vessels and the significance for thermal ablative therapies

Ablative therapies such as radio-frequency (RF) ablation are increasingly used for treatment of tumours in liver and other organs. Often large vessels limit the extent of the thermal lesion, and cancer cells close to the vessel survive resulting in local tumour recurrence. Accurate estimates of the heat convection coefficient h for large vessels will help improve ablation techniques, and are required for estimation of thermal lesion dimensions in simulations. Previous estimates of h did not consider that only part of the vessel is heated, and assumed uniform temperature distribution at the vessel wall. An analytical relationship between the heat convection coefficient, blood velocity and temperature is formulated. The heat convection coefficient evaluated will assist both simulations and design of proper protocols for in vivo measurements. The mathematical model developed in this work describes the exchange of heat between a solid surface and a moving fluid and it is based on energy and motion equations for Navier-Stokes fluids. A particular case of a laminar blood flow in the portal vein is studied when a portion of its surface is heated. The results show that heating a larger portion of the vessels reduces convective heat loss, which may result in more effective ablation strategies.

The emergent role of focal liver ablation techniques in the treatment of primary and secondary liver tumours

Only 20% of patients with primary or secondary liver tumours are suitable for resection because of extrahepatic disease or the anatomical distribution of their disease. These patients could be treated by ablation of the tumour, thus preserving functioning liver. This study presents a detailed review of established and experimental ablation procedures. The relative merits of each technique will be discussed and clinical data regarding the efficacy of the techniques evaluated. A literature search from 1966 to 2003 was undertaken using Medline, Pubmed and Web of Science databases. Keywords were Hepatocellular carcinoma, liver metastases, percutaneous ethanol injection, cryotherapy, microwave coagulation therapy, radiofrequency ablation, interstitial laser photocoagulation, focused high-intensity ultrasound, hot saline injection, electrolysis and acetic acid injection. Ablative techniques offer a promising therapeutic modality to treat unresectable tumours. Large-scale randomised controlled trials are required before widespread acceptance of these techniques can occur.

Initial experience with radiofrequency ablation for hepatic tumours in the Netherlands

AIMS

The aim of this study is to report initial experience with radiofrequency thermoablation (RFA) of malignant hepatic tumours.

METHODS

From June 1999 to November 2001, a seven centre study of 50 patients who had undergone RFA, included 102 primary or metastatic tumours. Multimodality therapy, complications, disease free survival and location of recurrence were recorded. Histopathologic examination was performed in a number of tumours treated with RFA and subsequently resected to determine the effect of RFA on the tissue level.

RESULTS

11 tumours (seven patients) were resected after prior treatment with RFA; NADH-diaphorase staining in all these tumours demonstrated non-viable tumour. Postoperative morbidity and mortality occurred in 14 patients and one patient, respectively, in three cases related to the RFA procedure. Median follow-up of 41 patients with non-resected RF ablated tumours was 11 months (range 1-24 months). 26 patients developed a recurrence of which three at the RFA site after 6-12 months.

CONCLUSIONS

RFA provides a simple method for local treatment of liver tumours. The introduction of this technique nevertheless involves morbidity and mortality.

Hepatic Radio frequency Ablation of Metastatic Ovarian Granulosa Cell Tumors

Intrahepatic recurrences of a granulosa cell tumor of the ovary after primary resection has traditionally been considered a relative contraindication to surgical management. Improvements in ablative technologies such as radiofrequency ablation (RFA) offer the surgeon additional alternatives in the management of selected intrahepatic tumors. We present a case report of an intrahepatic recurrence of a metastatic ovarian granulosa cell tumor 6 months after primary resection. The patient received RFA of the intrahepatic lesions and the patient remains free of detectable disease 14 months later. A review of the literature is presented. This is the first known report of the use of RFA for intrahepatic recurrence of a metastatic ovarian granulosa cell tumor. In selected cases of metastatic ovarian granulosa cell tumors to the liver RFA may increase the percentage of patients considered surgically treatable.

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.

The effect of hepatic inflow occlusion on laparoscopic radiofrequency ablation using simulated tumors

BACKGROUND

The purpose of this study was to determine the effect of hepatic inflow occlusion (the Pringle maneuver) on laparoscopic radiofrequency (RF) ablation.

METHODS

Using a previously validated agarose tissue-mimic model, 1-cm simulated hepatic tumors (three per animal) were laparoscopically ablated in five pigs with normal perfusion and then in five pigs with hepatic artery and portal vein occlusion. Energy was applied until tissue temperature reached 100 degrees C (warm-up) and thereafter for eight min. Specimens were examined immediately after treatment.

RESULTS

Vascular occlusion was successful in all cases per color-flow Doppler ultrasound. Pringle time was 11.4 +/- 1.6 min. Warm-up time (2.7 +/- 1.4 vs 20.2 +/- 14.0 min) was significantly faster in the Pringle group. Ablation diameter (34.8 +/- 2.9 vs 24.7 +/- 3.1 mm), proportion of round/ovoid lesions (93% vs 20%), ablation symmetry (100% vs 40%), and margin distance (5.1 +/- 3.0 vs 1.1 +/- 1.2 mm) were significantly better for the Pringle group than the No Pringle group, respectively.

CONCLUSION

Using a Pringle maneuver during laparoscopic RF ablation significantly enhances ablation geometry and results in larger margins.

Radiofrequence ablation of liver cancers

Primary and secondary malignant liver cancers are some of most common malignant tumors in the world. Chemotherapy and radiotherapy are not very effective against them. Surgical resection has been considered the only potentially curtive option, but the majority of patients are not candidates for resection because of tumor size, location near major intrahepatic blood vessels and bile ducts, precluding a margin-negative resection, cirrhotic, hepatitis virus infection or multifocial. Radiofrequence ablation (RFA), which is a new evolving effective and minimally invasive technique, can produce coagulative necrosis of malignant tumors. RFA should be used percutaneously, laparscopically, or during the open laparotomy under the guidance of ultrasound, CT scan and MRI. RFA has lots of advantages superior to other local therapies including lower complications, reduced costs and hospital stays, and the possibility of repeated treatment. In general, RFA is a safe, effective treatment for unresectable malignant liver tumors less than 7.0 cm in diameter. We review the principle, mechanism, procedures and experience with RFA for treating malignant liver tumors.

An increase in body temperature during radiofrequency ablation of liver tumors

Radiofrequency ablation (RFA) therapy using an active needle electrode inserted into liver tumors has been used clinically. To avoid hyperthermia, we investigated the relationship between the total output energy of the applied radiofrequency wave and changes in body temperature (BT) in patients receiving RFA. Fifteen patients undergoing RFA of liver tumors with general anesthesia were enrolled. The total output energy of radiofrequency waves was calculated from the power and duration of RFA. Changes in rectal (T(rect)) and tympanic temperatures were measured throughout the study. The mean number of liver tumors per patient was 1.7 +/- 1.3. The mean RFA time was 30.0 +/- 26.3 min. The mean total output energy was 125,935 +/- 114,506 J. The mean value of T(rect) increased from 36.3 degrees C +/- 0.5 degrees C to 37.0 degrees C +/- 1.0 degrees C (P < 0.01). A linear correlation was obtained between the total output energy and the changes in T(rect), indicating that T(rect) increased approximately by 1 degrees C for every 3000 J/kg of total output energy. The increase in BT during RFA of liver tumors under general anesthesia is predictable. Close observation of total output energy delivered and BT are required, and preparation of cooling measures is important, in RFA of liver tumors.

IMPLICATIONS

The increase in body temperature (BT) is predictable during radiofrequency ablation (RFA) of liver tumors under general anesthesia. Close observation of total output energy delivered and BT are required, and preparation of cooling measures is important, in RFA of liver tumors.

Percutaneous tumor ablation with radiofrequency

BACKGROUND

Radiofrequency thermal ablation (RFA) is a new minimally invasive treatment for localized cancer. Minimally invasive surgical options require less resources, time, recovery, and cost, and often offer reduced morbidity and mortality, compared with more invasive methods. To be useful, image-guided, minimally invasive, local treatments will have to meet those expectations without sacrificing efficacy.

METHODS

Image-guided, local cancer treatment relies on the assumption that local disease control may improve survival. Recent developments in ablative techniques are being applied to patients with inoperable, small, or solitary liver tumors, recurrent metachronous hereditary renal cell carcinoma, and neoplasms in the bone, lung, breast, and adrenal gland.

RESULTS

Recent refinements in ablation technology enable large tumor volumes to be treated with image-guided needle placement, either percutaneously, laparoscopically, or with open surgery. Local disease control potentially could result in improved survival, or enhanced operability.

CONCLUSIONS

Consensus indications in oncology are ill-defined, despite widespread proliferation of the technology. A brief review is presented of the current status of image-guided tumor ablation therapy. More rigorous scientific review, long-term follow-up, and randomized prospective trials are needed to help define the role of RFA in oncology.

Bleeding Hepatic Adenoma: Expectant Treatment to Limit the Extent of Liver Resection

Hepatic adenomas (HAs) are benign but can present as an acute surgical emergency. The relationship between HA and oral contraceptives (OCs) has been well documented and there have been several reports of tumor regression after the withdrawal of hormonal agents. However, not all HAs regress in this manner; have been reported to remain stable, increase in size, hemorrhage, or rarely, undergo malignant transformation. Given the unpredictable nature of these lesions they are generally treated surgically. In July 1995 a patient with a 6-year history of OC use was admitted with a history of sudden-onset right upper quadrant abdominal pain of 2 days’ duration. The clinical picture and imaging studies led to the diagnosis of a bleeding hepatic adenoma without rupture. She was treated expectantly for a period of 14 months before surgery. This allowed the tumor to significantly decrease in size and thus limit the extent of resection. If the patient presented in this case had undergone surgery at the time of initial diagnosis a right hepatic lobectomy as opposed to a wedge resection would have been required. Treating this patient expectantly significantly decreased the potential morbidity associated with a larger resection.

Evaluation of thermal therapy in a prostate cancer model using a wet electrode radiofrequency probe

PURPOSE

To determine the temperature-time threshold of local cell death in vivo for thermal therapy in a prostate cancer animal model and to use this value as a benchmark to quantify global tissue injury.

MATERIALS AND METHODS

Two studies were designed in the Dunning AT-1 rat prostate tumor hind limb model. For both studies, a wet electrode radiofrequency (RF) probe was used to deliver 40 W of energy for 18 to 62 seconds after a 30-second infusion of hypertonic saline/Hypaque through the RF antenna. Thermal history measurements were obtained in tumors from at least two Fluoroptic probes placed radially 5 mm from the axis of a RF probe and 10 mm below the surface of the tissue. In study 1, the thermal history required for irreversible cell injury was experimentally determined by comparing the predicted injury accumulation (omega) with cell viability at the fluoroptic probe locations using an in vivo-in vitro assay. The omega value was calculated from the measured thermal histories using an Arrhenius damage model. In study 2, RF energy was applied for 40 seconds in all cases. At 1, 3, and 7 days after thermal therapy, triphenyltetrazolium chloride dye (TTC) and histologic analyses were performed to assess global tissue injury within a 5-mm radius from the axis of the RF probe.

RESULTS

Study 1 showed that cell survival dropped to 0 for 0.42 < omega < 0.7. This result was the basis for selection of 40 seconds of RF thermal therapy in study 2, which yielded omegaave = 0.5 in the tissue 5 mm from the probe axis. Both TTC and histology analysis showed that sham-treated tissue was not irreversibly injured. However, there was an inherent heterogeneity present in the tumor that accounted for as much as 15% necrosis in control or sham-treated tissue. In contrast, at 1, 3, and 7 days after therapy, significantly less enzyme activity was observed by TCC in thermally treated tissue compared with sham-treated tissue (35 v 85%; P < 0.001). Histologic analysis of thermally treated tissues revealed a gradual increase in the percent of coagulative necrosis (47%-70%) with a concomitant decrease in the percentage of shocked cells (53%-28%). At day 7, <3% viability was observed in treated tumors compared with 90% viability in sham-treated tissue.

CONCLUSION

The threshold of cellular injury in vivo corresponded to omega > 0.7 (> or =48 degrees C for 40 seconds). Global tissue injury could be conservatively predicted on the basis of local thermal histories during therapy.

Laparoscopic and computed tomography-guided percutaneous radiofrequency ablation of renal tissue: acute and chronic effects in an animal model

OBJECTIVES

To evaluate the laparoscopic and percutaneous delivery of impedance-based radiofrequency ablation (RFA) of the kidney by studying the acute and chronic clinical, radiographic, and histopathologic effects in the porcine model.

METHODS

Eight kidneys from 4 pigs underwent laparoscopic RFA. Six kidneys from 3 additional pigs received computed tomography (CT)-guided, percutaneous RFA. CT scans were performed immediately after RFA and before harvest at 2 hours, 24 hours, 3 weeks, and 13 weeks. The gross, radiographic, and histopathologic changes were recorded for each period.

RESULTS

Grossly, the RFA lesions were sharply demarcated, measuring 3 to 5 cm. Two major complications (14%) occurred (one urinoma, one psoas muscle injury) in 14 ablations. No deaths or significant blood loss occurred as a result of RFA. Radiographically, the immediate CT scanning demonstrated small perinephric hematomas and wedge-shaped defects. Delayed CT showed nonenhancing defects up to 5 cm. Color-flow and power Doppler were unable to distinguish significant tissue changes during RFA. The histopathologic evaluation revealed marked inflammation surrounding the necrotic regions in the early lesions; chronic lesions were characterized by dense fibrosis. The tissue temperatures ranged from 62 degrees to 118 degrees C in the area of ablation.

CONCLUSIONS

RFA is readily delivered laparoscopically or percutaneously with minimal morbidity. Impedance-based application of radiofrequency energy allows monitoring and control of ablation. Using a multi-antenna probe, areas of tissue up to 5 cm can be completely destroyed. The RFA lesion can be monitored as a nonenhancing cortical defect on CT.

Radiofrequency ablation of unresectable hepatic malignancies: lessons learned

Radiofrequency ablation (RFA) is increasingly used for the local destruction of unresectable hepatic malignancies. Relative contraindications include tumors in proximity to vital structures that may be injured by RFA and lesions whose size exceeds the ablation capabilities of the probe system employed. Given current technology, we believe that RFA should be cautiously utilized for lesions greater than 5 cm in diameter. Open (celiotomy) and laparoscopic approaches to RFA allow intraoperative ultrasonography, which may demonstrate occult hepatic disease. In addition, RFA performed via celiotomy can be accompanied by resection or cryosurgical ablation, and isolation of the liver from adjacent organs. Percutaneous RFA should be reserved for patients who cannot undergo general anesthesia, those with recurrent or progressive lesions, and those with smaller lesions sufficiently isolated from adjacent organs. Complications may be minimized when these approaches are selectively applied.

Radiofrequency ablation of hepatocellular cancer in 110 patients with cirrhosis

OBJECTIVE

To determine the treatment efficacy, safety, local tumor control, and complications related to radiofrequency ablation (RFA) in patients with cirrhosis and unresectable hepatocellular carcinoma (HCC).

SUMMARY BACKGROUND DATA

Most patients with HCC are not candidates for resection because of tumor size, location, or hepatic dysfunction related to cirrhosis. RFA is a technique that permits in situ destruction of tumors by means of local tissue heating.

METHODS

One hundred ten patients with cirrhosis and HCC (Child class A, 50; B, 31; C, 29) were treated during a prospective study using RFA. Patients were treated with RFA using an open laparotomy, laparoscopic, or percutaneous approach with ultrasound guidance to place the RF needle electrode into the hepatic tumors. All patients were followed up at regular intervals to detect treatment-related complications or recurrence of disease.

RESULTS

All 110 patients were followed up for at least 12 months after RFA (median follow-up 19 months). Percutaneous or intraoperative RFA was performed in 76 (69%) and 34 patients (31%), respectively. A total of 149 discrete HCC tumor nodules were treated with RFA. The median diameter of tumors treated percutaneously (2.8 cm) was smaller than that of lesions treated during laparotomy (4.6 cm). Local tumor recurrence at the RFA site developed in four patients (3.6%); recurrent HCC subsequently developed in other areas of the liver in all four. New liver tumors or extrahepatic metastases developed in 50 patients (45. 5%), but 56 patients (50.9%) had no evidence of recurrence. There were no treatment-related deaths, but complications developed in 14 patients (12.7%) after RFA.

CONCLUSIONS

In patients with cirrhosis and HCC, RFA produces effective local control of disease in a significant proportion of patients and can be performed safely with minimal complications.

Radiofrequency ablation of 231 unresectable hepatic tumors: indications, limitations, and complications

BACKGROUND

Radiofrequency ablation (RFA) is increasingly used for the local destruction of unresectable hepatic malignancies. There is little information on its optimal approach or potential complications.

METHODS

Since late 1997, we have undertaken 91 RFA procedures to ablate 231 unresectable primary or metastatic liver tumors in 84 patients. RFA was performed via celiotomy (n = 39), laparoscopy (n = 27), or a percutaneous approach (n = 25). Patients were followed with spiral computed tomographic (CT) scans at 1 to 2 weeks postprocedure and then every 3 months for 2 years.

RESULTS

Intraoperative ultrasound (IOUS) detected intrahepatic disease not evident on the preoperative scans of 25 of 66 patients (38%) undergoing RFA via celiotomy or laparoscopy. In 38 of 84 patients (45%), RFA was combined with resection or cryosurgical ablation (CSA), or both. RFA was used to treat an average of 2.8 lesions per patient, and the median size of treated lesions was 2 cm (range, 0.3-9 cm). The average hospital stay was 3.6 days overall (1.8 days for percutaneous and laparoscopic cases). Ten patients underwent a second RFA procedure (sequential ablations) and, in one case, a third RFA procedure for large (one patient), progressive (seven patients), and/or recurrent (three patients) lesions. Seven (8%) patients had complications: one skin burn; one postoperative hemorrhage; two simple hepatic abscesses; one hepatic abscess associated with diaphragmatic heat necrosis following sequential percutaneous ablations of a large lesion; one postoperative myocardial infarction; and one liver failure. There were three deaths, one (1%) of which was directly related to the RFA procedure. Three of the complications, including one RFA-related death, occurred after percutaneous RFA. At a median follow-up of 9 months (range, 1-27 months), 15 patients (18%) had recurrences at an RFA site, and 36 patients (43%) remained clinically free of disease.

CONCLUSIONS

Celiotomy or laparoscopic approaches are preferred for RFA because they allow IOUS, which may demonstrate occult hepatic disease. Operative RFA also allows concomitant resection, CSA, or placement of a hepatic artery infusion pump, and isolation of the liver from adjacent organs. Percutaneous RFA should be reserved for patients at high risk for anesthesia, those with recurrent or progressive lesions, and those with smaller lesions sufficiently isolated from adjacent organs. Complications may be minimized when these approaches are applied selectively.

Supraphysiological thermal injury in Dunning AT-1 prostate tumor cells

To investigate the potential application of thermal therapy in the treatment of prostate cancer, the effects of supraphysiological temperatures (40-70 degrees C) for clinically relevant time periods (approximately 15 minutes) were experimentally studied on attached Dunning AT-1 rat prostate cancer cells using multiple assays. The membrane and reproductive machinery were the targets of injury selected for this study. In order to assess membrane injury, the leakage of calcein was measured dynamically, and the uptake of PI was measured postheating (1-3 hours). Clonogenicity was used as a measure of injury to the reproductive machinery 7 days post-injury after comparable thermal insults. Experimental results from all three assays show a broad trend of increasing injury with an increase in temperature and time of insult. Membrane injury, as measured by the fluorescent dye assays, does not correlate with clonogenic survival for many of the thermal histories investigated. In particular, the calcein assay at temperatures of < or = 40 degrees C led to measurable injury accumulation (dye leakage), which was considered sublethal, as shown by significant survival for comparable insult in the clonogenic assay. Additionally, the PI uptake assay used to measure injury post-thermal insult shows that membrane injury continues to accumulate after thermal insult at temperatures > or = 50 degrees C and may not always correlate with clonogenicity at hyperthermic temperatures such as 45 degrees C. Last, although the clonogenic assay yields the most accurate cell survival data, it is difficult to acquire these data at temperatures > or = 50 degrees C because the thermal transients in the experimental setup are significant as compared to the time scale of the experiment. To improve prediction and understanding of thermal injury in this prostate cancer cell line, a first-order rate process model of injury accumulation (the Arrhenius model) was fit to the experimental results. The activation energy (E) obtained using the Arrhenius model for an injury criterion of 30 percent for all three assays revealed that the mechanism of thermal injury measured is likely different for each of the three assays: clonogenics (526.39 kJ/mole), PI (244.8 kJ/mole), and calcein (81.33 kJ/mole). Moreover, the sensitivity of the rate of injury accumulation (d omega/dt) to temperature was highest for the clonogenic assay, lowest for calcein leakage, and intermediate for PI uptake, indicating the strong influence of E value on d omega/dt. Since the clonogenic assay is linked to the ultimate survival of the cell and accounts for all lethal mechanisms of cellular injury, the E and A values obtained from clonogenic study are the best values to apply to predict thermal injury in cells. For higher temperatures (> or = 50 degrees C) indicative of thermal therapies, the results of PI uptake can be used as a conservative estimate of cell death (underprediction). This is useful until better experimental protocols are available to account for thermal transients at high temperature to assess clonogenic ability. These results provide further insights into the mechanisms of thermal injury in single cell systems and may be useful for designing optimal protocols for clinical thermal therapy.

Radiofrequency Ablation: A Novel Primary and Adjunctive Ablative Technique for Hepatic Malignancies

The majority of primary and metastatic tumors of the liver are not amenable to surgical resection at presentation. Radiofrequency ablation (RFA) is a new modality for local tumor destruction with minimal local and systemic complications. We prospectively reviewed the experience with RFA at a single institute as a primary or adjunctive ablative technique in the treatment of hepatic malignancies. Between November 1997 and December 1998, 30 patients with primary or metastatic hepatic lesions were treated with RFA at the John Wayne Cancer Institute and the Cancer Center at Century City Hospital. Pathology of the treated lesions included colorectal metastases (29 in 14 patients), neuroendocrine metastases (29 in 4 patients), noncolorectal metastases (29 in 9 patients), and hepatocellular carcinoma (6 in 3 patients). Twelve patients underwent RFA laparoscopically, 12 at celiotomy, and the remaining 6 patients had percutaneous ablation. RFA was the only procedure in 17 patients, whereas the remainder underwent a combination of RFA and other procedures including resection, cryosurgical ablation, and hepatic artery infusion pump placement. Median length of stay for all patients was 6 days (2 days for laparoscopic patients). A single complication of a delayed intrahepatic abscess was noted in this series (3%). There have been no deaths associated with RFA. At a median follow-up of 5 months, 16 patients remain disease free, and 10 are alive with disease. RFA is a safe and effective method of tumor ablation for hepatic malignancies. This technique can be performed laparoscopically, at celiotomy, or percutaneously and can be used as a primary technique or in conjunction with other interventional procedures.

Radiofrequency ablation of unresectable primary and metastatic hepatic malignancies: results in 123 patients

OBJECTIVE

To describe the safety and efficacy of radiofrequency ablation (RFA) to treat unresectable malignant hepatic tumors in 123 patients.

BACKGROUND

The majority of patients with primary or metastatic malignancies confined to the liver are not candidates for resection because of tumor size, location, or multifocality or inadequate functional hepatic reserve. Local application of heat is tumoricidal; therefore, the authors investigated a novel RFA system to treat patients with unresectable hepatic cancer.

PATIENTS AND METHODS

Patients with hepatic malignancies were entered into a prospective, nonrandomized trial. The liver tumors were treated percutaneously or during surgery under ultrasound guidance using a novel LeVeen monopolar array needle electrode and an RF 2000 generator. All patients were followed to assess complications, treatment response, and recurrence of malignant disease.

RESULTS

RFA was used to treat 169 tumors (median diameter 3.4 cm, range 0.5 to 12 cm) in 123 patients. Primary liver cancer was treated in 48 patients (39.1%), and metastatic liver tumors were treated in 75 patients (60.9%). Percutaneous and intraoperative RFA was performed in 31 patients (35.2%) and 92 patients (74.8%), respectively. There were no treatment-related deaths, and the complication rate after RFA was 2.4%. All treated tumors were completely necrotic on imaging studies after completion of RFA treatments. With a median follow-up of 15 months, tumor has recurred in 3 of 169 treated lesions (1.8%), but metastatic disease has developed at other sites in 34 patients (27.6%).

CONCLUSIONS

RFA is a safe, well-tolerated, and effective treatment to achieve tumor destruction in patients with unresectable hepatic malignancies. Because patients are at risk for the development of new metastatic disease after RFA, multimodality treatment approaches that include RFA should be investigated.

Radiofrequency ablation followed by resection of malignant liver tumors

BACKGROUND

Radiofrequency ablation (RFA) has recently been used to treat liver tumors, but few clinical reports have described the pathological characteristics of radiofrequency ablation in human specimens. This study delineates the gross pathologic and histochemical changes induced by RFA in benign and malignant human liver tissue and confirms the tumor necrosis described in early clinical reports.

METHODS

Ten patients with metastatic tumors of the liver received a single treatment of ultrasound-guided percutaneous RFA to 12 tumors. Hepatic resection was carried out within 6 weeks of RFA. Specimens were stained with standard hematoxylin and eosin stain followed by oxidative stain to determine if there was evidence of viable tumor within the zone of ablation.

RESULTS

Nine of the 12 ablations were resected. Microscopic examination within the zone of ablation showed successful ablation in 8 of the 9 resected ablations.

CONCLUSIONS

Percutaneous RFA creates well-circumscribed areas of tumor necrosis with apparent cell death using an oxidative stain. Further investigation is encouraged to determine the clinical effectiveness of radiofrequency ablation in the complete destruction of liver tumors for palliative or curative intent.

Radiofrequency ablation of porcine liver in vivo: effects of blood flow and treatment time on lesion size

OBJECTIVE

To determine, in vivo, the effect of radiofrequency ablation (RFA) treatment time and tissue blood flow on the size and shape of the resulting necrotic lesion in porcine liver.

SUMMARY BACKGROUND DATA

Radiofrequency ablation is an electrosurgical technique that uses a high frequency alternating current to heat tissues to the point of desiccation (thermal coagulation). Radiofrequency ablation is well established as the treatment of choice for many symptomatic cardiac arrhythmias because of its ability to create localized necrotic lesions in the cardiac conducting system. Until recently, a major limitation of RFA was the small lesion size created by this technique. Development of bipolar and multiple-electrode RFA probes has enabled the creation of larger lesions and therefore has expanded the potential clinical applications of RFA, which includes the treatment of liver tumors. A basic understanding of factors that influence RFA lesion size in vivo is critical to the success of this treatment modality. The optimal RFA technique, which maximizes liver lesion size, has yet to be determined. Theoretically, lesion size varies directly with time of application of the RF current, and inversely with blood flow, but these relationships have not been previously studied in the liver.

METHODS

Six animals underwent hepatic RFA (460 kHz), for 5, 7.5, 10, 12.5, 15, and 20 minutes. Identical, predetermined anatomic areas of the liver were ablated in each animal. Two additional animals underwent 12 RFA treatments -- 6 with vascular inflow occlusion (Pringle maneuver) and 6 with uninterrupted hepatic blood flow. Animals were euthanized and the livers were removed for gross pathologic examination. All lesions were measured in three dimensions and photographed. Tissues were examined by routine histology and by histochemistry to determine viability.

RESULTS

Increasing duration of RFA application from 5 through 20 minutes did not create lesions of larger diameter, but this time increase did predict deeper lesion production (beta = 0.34, p = 0.04). A range of lesion shapes were created from four separate ovals (corresponding to each electrode), to larger ovals intersecting to form a cross, to spheroid lesions. The number of blood vessels in close proximity to the probe tip (within a 1-cm radius from the center of the lesion) strongly predicted minimum lesion diameter (beta = -0.61, p = 0.0001) and lesion volume (beta = -0.56, p = 0.0004). This negative effect of blood flow on lesion size was confirmed experimentally. Radiofrequency ablation lesions created during a Pringle maneuver were significantly larger in all three dimensions than lesions created without a Pringle maneuver: minimum diameter was 3.0 cm (with Pringle) versus 1.2 cm (p = 0.002), maximum diameter was 4.5 cm (with Pringle) versus 3.1 cm (p = 0.002), depth was 4.8 cm (with Pringle) versus 3.1 cm (p < 0.001), and lesion volume was 35.0 cm3 (with Pringle) versus 6.5 cm3 (p < 0.001).

CONCLUSIONS

Blood flow is a strong predictor of all RFA lesion dimensions in porcine liver in vivo, whereas a change of treatment time from 5 to 20 minutes is predictive only of lesion depth, but not diameter or volume.

Laparoscopic thermal ablation of hepatic neuroendocrine tumor metastases

BACKGROUND

Neuroendocrine tumor metastases to the liver are generally slow growing, but patients suffer from hormone hypersecretion despite aggressive multimodality therapy. A minimally invasive method of tumor ablation affords symptomatic improvement with minimal morbidity.

METHODS

Radiofrequency electrical energy is delivered to tissues via a 4-prong catheter resulting in tissue heating to 60 to 70 degrees C and cell death. Porcine studies were conducted to define appropriate parameters for energy delivery and then applied to patients using laparoscopic techniques.

RESULTS

In the porcine model 3.5 to 4 cm lesions were reproducibly created in 15 minutes using 30 to 50 W of power. The ablation process was monitored via temperature feedback from thermocouples in the catheter tips and by a hyperechoic blush noted on ultrasonography. Laparoscopic thermal ablation of 13 tumors in six patients with carcinoid (two patients), gastrinoma, insulinoma, nonsecreting islet cell cancer, or medullary thyroid cancer was performed. There were no intraoperative complications, and all patients were discharged the next day. Successful ablation was confirmed by spiral-computed tomography and by symptomatic improvement in patients with secreting tumors.

CONCLUSIONS

Laparoscopic thermal ablation of hepatic tumors is a novel, minimally invasive method of providing effective cytoreduction of neuroendocrine tumors metastatic to the liver.

Ex vivo experiment on radiofrequency liver ablation with saline infusion through a screw-tip cannulated electrode

PURPOSE

To investigate whether radiofrequency (RF) therapy with hypertonic saline infusion through a hollow screw-tip electrode can cause a lesion size suitable for liver tumor ablation.

MATERIALS AND METHODS

RF tissue ablation of 180 sites was performed by using a hollow screw-tip electrode in 40 freshly excised swine livers. Under both power and temperature control modes, the ablation effects with and without various regimes of 5% hypertonic saline (1 ml/min) prior to and/or during the procedure were compared by measuring the size of lesions at dissection and confirmed by T1 and T2 weighted magnetic resonance (MR) imaging.

RESULTS

The maximal lesion diameter of 5.5 cm was reached at 30 W with saline infusion 1 min prior to and during 12 min of ablation. The smaller sizes (P < 0.01) between 0.3 and 2.5 cm in diameter were met with noninfusion or preinfusion-only groups. The RF ablation lesions appeared as hyper- and hypointense areas on T1 and T2 MR images, respectively.

CONCLUSIONS

RF ablation in combination with present hollow screw-tip electrode and saline infusion allows for necrotic development of suitable size for liver tumor ablation. Such ablated lesions can be visualized with MR imaging.

Liver tumor ablation techniques

Despite advances in surgical technique, patients with primary and secondary liver tumors remain a difficult management problem, as most tumors are unresectable at presentation. Alternative therapies, involving the in situ destruction of liver tumors, have recently come under scrutiny as palliative options. Percutaneous ethanol injection and cryosurgery have been advocated, but both have associated technical difficulties and adverse effects. Novel liver tumor ablation techniques have recently been developed that work via the induction of localized hyperthermia. There is mounting evidence to support a hypothesis that cancer cells are more selectively sensitive to heat than are normal cells, due to the poor blood supply of neoplastic tissue and the decreased vasodilatation capacity of the neovascular bed. These ablative modalities induce a variable degree of tumor necrosis in unresectable tumors, and therefore may provide useful palliation. Clinical trials are needed to determine the true nature and degree of any palliative benefit. In addition, the determinants of treatment efficacy and the predictability of the necrotic zone must be better understood before these techniques can be contemplated as alternatives to liver resection for cure.

Gasless laparoscopic resection of hepatocellular carcinoma (HCC) in cirrhosis

Liver resection by open surgery remains the method of choice for treatment of hepatocellular carcinoma (HCC) in cirrhotic patients with compensated liver function. Laparoscopy for surgical treatment of hepatic diseases is at an early stage. Laparoscopy has been often proposed for diagnosis, staging of hepatic malignancy, treatment of hepatic cyst or benign tumors, but very few laparoscopic treatments of hepatic malignancies have been reported at present and always using conventional CO2 laparoscopy. We describe herein the operative treatment of a single subglissonian HCC of segment III in a child, HCV (hepatitis C virus)-related cirrhosis. A nonanatomical wedge resection was performed by gasless laparoscopic technique using a mechanical retractor obviating the creation of the pneumoperitoneum and of the sealed environment. The technique, in selected cases, is a simple, safe, and effective surgical method. The gasless technique guarantees a clear vision, it makes possible the continuous suction of smoke and fluids, it allows the use of conventional instruments for classic maneuvers of the liver surgery (Pringle maneuver), and the easy management of suturing. The present case has proved to be another abdominal procedure that can be carried out with all the advantages of gasless minimally invasive surgery.