Radiofrequency ablation for malignant liver tumor

An Ionic Liquid Ablation Agent for Local Ablation and Immune Activation in Pancreatic Cancer

Pancreatic ductal adenocarcinoma rapidly acquires resistance to chemotherapy, remaining a fatal disease. Immunotherapy is one of the breakthroughs in cancer treatment, which includes immune checkpoint inhibitors, chimeric antigen receptor T-cell immunotherapy, and neoantigen vaccines. However, immunotherapy has not achieved satisfactory results in the treatment of pancreatic cancer. Immunogenic death comprises proinflammatory cell death, which provides a way to enhance tumor immunogenicity and promote an immune response in solid tumors. Herein, an ionic liquid ablation agent (LAA), synthesized from choline and geranic acid, which triggers necrosis-induced immunotherapy by remodeling an immunosuppressive "cold" tumor to an immune activated "hot" tumor is described. The results indicate that LAA-treated tumor cells can enhance immunogenicity, inducing dendritic cell maturation, macrophage M1 polarization, and cytotoxic T lymphocyte infiltration. The results of the present study provide a novel strategy for solid tumor immunotherapy.

Techniques and Algorithms for Hepatic Vessel Skeletonization in Medical Images: A Survey

Hepatic vessel skeletonization serves as an important means of hepatic vascular analysis and vessel segmentation. This paper presents a survey of techniques and algorithms for hepatic vessel skeletonization in medical images. We summarized the latest developments and classical approaches in this field. These methods are classified into five categories according to their methodological characteristics. The overview and brief assessment of each category are provided in the corresponding chapters, respectively. We provide a comprehensive summary among the cited publications, image modalities and datasets from various aspects, which hope to reveal the pros and cons of every method, summarize its achievements and discuss the challenges and future trends.

How to Treat Hepatocellular Carcinoma in Elderly Patients

Hepatocellular carcinoma (HCC) is the primary tumour of the liver with the greatest incidence, particularly in the elderly. Additionally, improvements in the treatments for chronic liver diseases have increased the number of elderly patients who might be affected by HCC. Little evidence exists regarding HCC in old patients, and the elderly are still underrepresented and undertreated in clinical trials. In fact, this population represents a complex subgroup of patients who are hard to manage, especially due to the presence of multiple comorbidities. Therefore, the choice of treatment is mainly decided by the physician in the clinical practice, who often tend not to treat elderly patients in order to avoid the possibility of adverse events, which may alter their unstable equilibrium. In this context, the clarification of the optimal treatment strategy for elderly patients affected by HCC has become an urgent necessity. The aim of this review is to provide an overview of the available data regarding the treatment of HCC in elderly patients, starting from the definition of "elderly" and the geriatric assessment and scales. We explain the possible treatment choices according to the Barcelona Clinic Liver Cancer (BCLC) scale and their feasibility in the elderly population.

Randomized clinical trial of hepatic resection versus radiofrequency ablation for early-stage hepatocellular carcinoma

Background

Hepatic resection and radiofrequency ablation (RFA) are treatment options for early-stage hepatocellular carcinoma (HCC). Whether tumour recurrence and long-term survival favour either treatment has not been established. This randomized trial aimed to test the hypothesis that RFA is superior to hepatic resection in terms of lower tumour recurrence rate and better long-term survival.

Methods

Patients with early-stage HCC (solitary tumour no larger than 5 cm; or no more than 3 tumours, each 3 cm or smaller) were randomized into hepatic resection and RFA groups. Demographic and clinical characteristics, and short- and long-term outcome measures were compared between groups. Primary and secondary outcome measures were overall tumour recurrence and survival respectively.

Results

Clinicopathological data were similar in the two groups, which each contained 109 patients. The RFA group had a shorter treatment duration, less blood loss and shorter hospital stay than the resection group. Mortality and morbidity rates were similar in the two groups. The overall tumour recurrence rate was similar in the resection and RFA groups (71·3 versus 81·7 per cent respectively). The 1-, 3-, 5- and 10-year overall survival rates were 94·5, 80·6, 66·5 and 47·6 per cent respectively in the resection group, compared with 95·4, 82·3, 66·4 and 41·8 per cent in the RFA group (P = 0·531). Corresponding disease-free survival rates were 74·1, 50·9, 41·5 and 31·9 per cent in the resection group, and 70·6, 46·6, 33·6 and 18·6 per cent in the RFA group (P = 0·072).

Conclusion

RFA for early-stage HCC is not superior to hepatic resection, in terms of tumour recurrence, overall survival and disease-free survival. Registration number: HKUCTR-10 (http://www.hkuctr.com).

Efficacy and Safety of Ultrasound-Guided Radiofrequency Ablation for Treating Low-Risk Papillary Thyroid Microcarcinoma: A Prospective Study

BACKGROUND

Papillary thyroid microcarcinoma (PTMC) has a high incidence and a good prognosis. Surgical operation for all PTMC might be an overtreatment. The objective of this study was to evaluate the efficacy and safety of ultrasound (US)-guided radiofrequency ablation (RFA) for treating low-risk PTMC.

METHODS

Ninety-eight PTMC in 92 patients were included in this study. US and contrast-enhanced ultrasound (CEUS) examinations were performed before ablation. RFA was performed using the moving-shot technique. The ablation area exceeded the tumor edge to prevent marginal residue and recurrence. Patients were followed at 1, 3, 6, and 12 months and every six months thereafter. US and CEUS examinations were used to evaluate the ablation area. At three months after ablation, US-guided core-needle biopsy (CNB) was performed in the center, at the edge of the ablation area, and in the surrounding thyroid parenchyma to exclude recurrence.

RESULTS

The mean tumor volume was 118.8 ± 106.9 mm³. The mean volume reduction ratio (VRR) was 0.47 ± 0.27, 0.19 ± 0.16, 0.08 ± 0.11, 0.04 ± 0.10, and 0 at 1, 3, 6, 12, and 18 months after RFA, respectively. Significant differences in the VRR were found between every two follow-up times before six months (p < 0.01), and no significant differences in the VRR were found between six months and after 12 months (p = 0.42). Of all the nodules, 10 (41.7%) resolved in six months, and 23 (95.8%) resolved in 12 months. No residual or recurrent tumor tissue was detected in RFA area or in residual thyroid tissue during follow-up. No suspicious metastatic lymph nodes were detected. The histological pathology results of US-guided CNB confirmed the absence of residual or recurrent tumor. No major complications were encountered.

CONCLUSIONS

RFA can effectively eliminate low-risk PTMC with a very small complication rate. RFA may be an alternative strategy for the treatment of PTMC.

Surgical resection and radiofrequency ablation initiate cancer in cytokeratin-19+- liver cells deficient for p53 and Rb

The long term prognosis of liver cancer patients remains unsatisfactory because of cancer recurrence after surgical interventions, particularly in patients with viral infections. Since hepatitis B and C viral proteins lead to inactivation of the tumor suppressors p53 and Retinoblastoma (Rb), we hypothesize that surgery in the context of p53/Rb inactivation initiate de novo tumorigenesis.

We, therefore, generated transgenic mice with hepatocyte and cholangiocyte/liver progenitor cell (LPC)-specific deletion of p53 and Rb, by interbreeding conditional p53/Rb knockout mice with either Albumin-cre or Cytokeratin-19-cre transgenic mice.

We show that liver cancer develops at the necrotic injury site after surgical resection or radiofrequency ablation in p53/Rb deficient livers. Cancer initiation occurs as a result of specific migration, expansion and transformation of cytokeratin-19⁺-liver (CK-19⁺) cells. At the injury site migrating CK-19⁺ cells formed small bile ducts and adjacent cells strongly expressed the transforming growth factor β (TGFβ). Isolated cytokeratin-19⁺ cells deficient for p53/Rb were resistant against hypoxia and TGFβ-mediated growth inhibition. CK-19⁺ specific deletion of p53/Rb verified that carcinomas at the injury site originates from cholangiocytes or liver progenitor cells.

These findings suggest that human liver patients with hepatitis B and C viral infection or with mutations for p53 and Rb are at high risk to develop tumors at the surgical intervention site.

Potential of Radiofrequency Ablation in Combination with Immunotherapy in the Treatment of Hepatocellular Carcinoma

Radiofrequency ablation (RFA) is an important treatment option for patients with early hepatocellular carcinoma (HCC). RFA offers a reliable, reproducible modality to effectively treat hepatic lesions with minimal collateral damage to the surrounding hepatic parenchyma. In addition to traditional open operative techniques, RFA can be performed percutaneously or laparoscopically to minimize the physiologic insult to the patient. Due to the concomitant hepatic damage and dysfunction that often is present in patients with HCC these factors make RFA a frequently utilized therapeutic option. However, RFA is most efficacious in treating smaller tumors (≤ 2 cm), particularly when an ablation margin of ≥ 4-5 mm can be obtained. RFA has diminishing utility in larger tumors, resulting in reduced three and five year overall survival rates when compared to surgical resection. Multimodal approaches to include RFA with other standard and investigational approaches have become a subject of recent interest. RFA capably produces cellular destruction causing liberation of a substantial amount of antigens, many of which are tumor-specific providing a favorable environment for immune recognition. We propose that utilizing an immunotherapeutic approach in conjunction with RFA is the next logical step in the treatment of HCC. In this review, we summarize how RFA modulates antitumor immunity and works in concert with immunotherapy in the treatment of HCC. The information provided is expected to help the future design of novel RFA-integrated immunotherapies which are able to generate durable and powerful antitumor immune response to achieve optimal tumor control.

Long-term survival following radiofrequency ablation of colorectal liver metastases: A retrospective study

AIM: To retrospectively evaluate the long-term survival of patients that received radiofrequency ablation (RFA) therapies of colorectal liver metastases.

METHODS: In 2005 to 2008, RFA of 105 colorectal liver metastases (CRLM) were performed on 49 patients in our institution. The liver metastases were evaluated, both before and after ablation therapies, with contrast enhanced computerised tomography and contrast enhanced ultrasonography. Histological evidence of malignant liver metastases was obtained in the few instances where contrast enhanced ultrasonography gave equivocal results. Accesses to the CRLM were guided ultrasonically in all patients. The data obtained from records of these ablations were retrospectively analysed and survival data were compared with existing studies in the literature.

RESULTS: 1-, 2-, 3-, 4- and 5-year survival rates, when no stringent selection criteria were applied, were 92%, 65%, 51%, 41% and 29% respectively. To explore the impact of the number and size of CRLM on patients’ survival, an exclusion of 13 patients (26.5%) with number of CRLM ≥ 5 and tumour size ≥ 40 mm resulted in 1-, 2-, 3-, 4- and 5-year survival rates improving to 94%, 69%, 53%, 42% and 31% respectively. It is of note that 9 of 49 patients developed extra-hepatic metastases, not visible or seen on pre-treatment scans, just after RFA treatment. These patients had poorer survival. The development of extra-hepatic metastases in nearly 20% of the patients included in our study can partly account for modestly lower survival rates as compared with earlier studies in the literature.

CONCLUSION: Our study underscores the fact that optimum patients’ selection before embarking on RFA treatment is vitally important to achieving a superior outcome.

A comparison of acoustic cavitation detection thresholds measured with piezo-electric and fiber-optic hydrophone sensors

A Fabry-Perot interferometer fiber-optic hydrophone (FOH) was investigated for use as an acoustic cavitation detector and compared with a piezo-ceramic passive cavitation detector (PCD). Both detectors were used to measure negative pressure thresholds for broadband emissions in 3% agar and ex vivo bovine liver simultaneously. FOH-detected half- and fourth-harmonic emissions were also studied. Three thresholds were defined and investigated: (i) onset of cavitation; (ii) 100% probability of cavitation; and (iii) a time-integrated threshold where broadband signals integrated over a 3-s exposure duration, averaged over 5-10 repeat exposures, become statistically significantly greater than noise. The statistical sensitiviy of FOH broadband detection was low compared with that of the PCD (0.43/0.31 in agar/liver). FOH-detected fourth-harmonic data agreed best with PCD broadband (sensitivity: 0.95/0.94, specificity: 0.89/0.76 in agar/liver). The FOH has potential as a cavitation detector, particularly in applications where space is limited or during magnetic resonance-guided studies.

Percutaneous radiofrequency ablation versus surgical radiofrequency ablation for malignant liver tumours: the long-term results

BACKGROUND

Radiofrequency ablation (RFA) has been used to treat hepatocellular carcinoma (HCC) and liver metastases for more than 10 years with promising early outcomes. Preliminary results comparing percutaneous and surgical approaches have shown no difference in short-term outcomes. In this study, the longer-term outcomes were presented.

METHODS

Patients with liver malignancies treated by RFA were prospectively studied from 2003 to 2011. Post-ablation assessment by computed tomography (CT) scan and serum biochemistry was performed at regular intervals. Recurrence rates and long-term survival were analysed.

RESULTS

A total of 233 patients with liver malignancies (75.5% HCC and 24.5% liver metastases) were analysed. Three RFA approaches were used (percutaneous 58.4%, laparoscopic 9.4% and open 32.2%). The median follow-up time was 29 months. Complete ablation was achieved in 83.7%, with no difference between the two approaches. More wound and chest complications were observed in the surgical group. Intra-hepatic recurrences were observed in 69.5%; extra-hepatic recurrences were detected in 22.3%, with no difference between the two groups. There was no statistical difference between the two approaches in overall 1-, 3- and 5-year survival.

CONCLUSION

An extended period of follow-up in patients with liver malignancies showed that RFA is an effective treatment. No difference was demonstrated between the percutaneous and surgical approach, in terms of recurrence and survival.

Use of radiofrequency ablation in benign thyroid nodules: a literature review and updates

Successful thermal ablation using radiofrequency has been reported in various tumors including liver or kidney tumors. Nonsurgical minimally invasive ablative therapy such as radiofrequency ablation (RFA) has been reported to be a safe and efficient treatment option in managing symptomatic cold thyroid nodules or hyperfunctioning thyroid nodules. Pressure and cosmetic symptoms have been shown to be significantly improved both in the short and long terms after RFA. For hyperfunctioning thyroid nodules, RFA is indicated for whom surgery or radioiodine are not indicated or ineffective or for those who refuse surgery or radio-iodine. Improvement of thyroid function with decreased need for antithyroid medications has been reported. Complication rate is relatively low. By reviewing the current literature, we reported its efficacy and complications and compared the efficacy of RFA relative to other ablative options such as ethanol ablation and laser ablation.

Ki-67 is a prognostic biomarker of survival after radiofrequency ablation of liver malignancies

PURPOSE

To assess the predictive value of examinations of tissue adherent to multitined electrodes on local tumor progression-free survival (LPFS) and overall survival (OS) after liver tumor radiofrequency ablation (RFA).

METHODS

An institutional review board-approved, Health Insurance Portability and Accountability Act-compliant review identified 68 liver tumors treated with RFA in 63 patients with at least 3 years' follow-up. Tissue adherent to the electrode after liver tumor RFA was evaluated with proliferation (Ki-67) and apoptotic (caspase-3) markers. LPFS and OS were evaluated by Kaplan-Meier methodology and the log-rank test. Multivariate analysis assessed the effect of tumor size, pathology, and post-RFA tissue characteristics on LPFS and OS.

RESULTS

Post-RFA tissue examination classified 55 of the 68 tumors as completely ablated with coagulation necrosis, with cells positive for caspase-3 and negative for Ki-67 (CN). Thirteen had viable Ki-67-positive tumor cells. Mean liver tumor size was larger in the viable (V) group versus the CN group (3.4 vs. 2.5 cm, respectively; P = .017). For the V and CN groups, respectively, local tumor progression occurred in 12 (92 %) of 13 and 23 (42 %) of 55 specimens. One, 3-, and 5-year LPFS was 8 %, 8 %, and 8 %, and 79 %, 47 %, and 47 % (P < .001) for the V and CN groups, respectively. During a 63-month median follow-up, 92 % of patients in the V group and 58 % in the CN group died, resulting in 1-, 3-, and 5-year OS of 92 %, 25 %, and 8 % vs. 92 %, 59 %, and 33 % (P = .032), respectively.

CONCLUSIONS

Ki-67-positive tumor cells on the electrode after liver tumor RFA is an independent predictor of LPFS and OS. Size, initially thought to be an independent risk factor for local tumor progression in tumors 3-5 cm, does not hold its significance at long follow-up.

[Abscesso-colonic fistula following radiofrequency ablation therapy for hepatocellular carcinoma; a case successfully treated with histoacryl embolization]

Hepatocellular carcinoma (HCC) is one of the most common malignant neoplasms occuring worldwide. Although surgical resection still remains the treatment of choice for HCC, radiofrequency ablation (RFA) has emerged as reliable alternatives to resection. It is less invasive and can be repeated after short intervals for sequential ablation in case of multiple lesions. The most common complication of RFA is liver abscess, and bile duct injury such as bile duct stricture has been reported. This is a case report of a rare complication of abscesso-colonic fistula after RFA for HCC. The case was treated by percutaneous abscess drainage and antibiotics and occlusion of abscesso-colonic fistula with n-butyl-2-cyanoacrylate embolization.

Technical note: Radiofrequency ablation of hepatocellular carcinoma with contrast-enhanced ultrasound guidance: First Indian experience

Radiofrequency ablation (RFA) of hepatocellular carcinoma (HCC) is an established alternative treatment to surgery and intra-arterial chemotherapy, usually performed under contrast-enhanced CT scan guidance. We describe our experience with the use of contrast-enhanced ultrasound and contrast dynamics analysis for planning and monitoring RFA in a patient with HCC.

CT-guided radiofrequency ablation as a salvage treatment of colorectal cancer hepatic metastases developing after hepatectomy

PURPOSE

To evaluate the clinical outcomes of percutaneous radiofrequency (RF) ablation of colorectal cancer liver metastases (CLMs) that recur after hepatectomy.

MATERIALS AND METHODS

From December 2002 to December 2008, 71 CLMs that developed after hepatectomy were ablated in 56 patients. Medical records and imaging were reviewed to determine technique effectiveness/complete ablation (ie, ablation defect covering the entire tumor on 4-6-week postablation computed tomography [CT]), complications, and local tumor progression (LTP) at the site of ablation. LTP-free and overall survival were calculated by using Kaplan-Meier methodology. A modified clinical risk score (CRS) including nodal status of the primary tumor, time interval between diagnoses of the primary tumor and liver metastases, number of tumors, and size of the largest tumor was assessed for its effect on overall survival and LTP.

RESULTS

Tumor size ranged between 0.5 and 5.7 cm. Complete ablation was documented in 67 of 71 cases (94%). Complications included liver abscess (n = 1) and pleural effusion (n = 1). Median overall survival time was 31 months. One-, 2- and 3-year overall survival rates were 91%, 66%, and 41%, respectively. CRS was an independent factor for overall survival (74% for CRS of 0-2 vs 42% for CRS of 3-4 at 2 y; P = .03) and for LTP-free survival (66% for CRS of 0-2 vs 22% for CRS of 3-4 at 1 y after a single ablation; P <.01).

CONCLUSIONS

CT-guided RF ablation can be used to treat recurrent CLM after hepatectomy. A low CRS is associated with better clinical outcomes.

Right thoracic paravertebral anaesthesia for percutaneous radiofrequency ablation of liver tumours

OBJECTIVES

Percutaneous radiofrequency ablation (PRFA) of liver tumours performed under local anaesthesia and intravenous sedation can cause severe pain to patients. This prospective study evaluated the efficacy of a right thoracic paravertebral block (TPVB) for anaesthesia and analgesia during PRFA of liver tumours.

METHODS

20 patients, aged 44-74 years, with liver malignancies received a multiple injection TPVB at the T6-10 levels 30 min before the PRFA. An intravenous infusion of propofol (3-5 mg kg(-1) h(-1)) was administered to patients who requested to be sedated and intravenous fentanyl (25 µg bolus) was administered as rescue analgesia. Pain during the TPVB and PRFA was assessed using a numerical rating scale (NRS; 0, no pain; 10, worst imaginable pain). Patients were also assessed for residual pain and analgesic consumption during the 24 h after the intervention.

RESULTS

The TPVB was well tolerated and produced ipsilateral sensory anaesthesia with satisfactory spread (median (range); 8 (6-11) dermatomes). The PRFA procedure caused mild pain (mean (standard deviation, SD); NRS 1.4 (1.9)) during the insertion of the ablation needle and the peak pain intensity during the therapeutic burn was moderate (mean (SD); NRS 5.0 (3.3)) in severity. During the 24 h after the PRFA, patients reported minimal pain and consumed very few analgesics. The mean (SD) satisfaction score (0, totally dissatisfied; 10, very satisfied) of the patients was 8.9 (1.1) and that of the radiologists was 8.8 (1.4).

CONCLUSION

A right TPVB is safe and effective for anaesthesia and analgesia during PRFA of malignant liver tumours.

Combined resection and radiofrequency ablation for multifocal hepatocellular carcinoma: Prognosis and outcomes

AIM: To analyze the combined treatment of resection and intraoperative radiofrequency ablation (RFA) for multifocal hepatocellular carcinoma in terms of prognosis and surgical outcomes.

METHODS: This study was a retrospective case comparison study using prospectively collected data. The study covered the period from April 2001 to December 2006. The data of 200 patients with histologically confirmed hepatocellular carcinoma were reviewed. Nineteen patients (17 men and 2 women) having received resection in combination with RFA were chosen as subjects of the study (the combination group). Fifty-four patients (43 men and 11 women) having received resection alone were selected for comparison (the resection group). The two groups matched tumor number and tumor size, and all the patients in the two groups displayed no tumor rupture, major vascular involvement and distant metastasis. Their demographics, preoperative assessment, disease recurrence patterns, overall survival and disease-free survival were compared.

RESULTS: In the combination group, the median age was 65 years (range, 34-77 years), the median tumor number was 3 (range, 2-9), and the median tumor size was 6 cm (range, 1.2-14 cm). In the resection group, the median age was 51.5 years (range, 27-80 years, P = 0.003), the median tumor number was 3 (range, 2-9, P = 0.574), and the median tumor size was 6 cm (range, 1-14 cm, P = 0.782). The two groups were similar in characteristics of tumors and comorbidities, and had comparable results in preoperative liver function tests. All patients had Child-Pugh class A status. Bilobar involvement occurred in 14 patients (73.6%) in the combination group and 3 patients (5.5%) in the resection group (P = 0.04). Six patients (32%) in the combination group and 35 patients (65%) in the resection group underwent major hepatectomy. Thirteen patients (68%) in the combination group and 19 patients (35%) in the resection group underwent minor hepatectomy (P = 0.012). The combination group had fewer major resections (32% vs 65%, P = 0.012), less blood loss (400 vs 657 mL, P = 0.007), shorter operation time (270 vs 400 min, P = 0.001), and shorter hospital stay (7 vs 8.5 d, P = 0.042). The two groups displayed no major differences in surgical complications (15.8% vs 31.5%, P = 0.24), disease recurrence (63.2% vs 50%, P = 0.673), hospital mortality (5.3% vs 5.6%, P = 1), and overall survival (53 vs 44.5 mo, P = 0.496).

CONCLUSION: Safe and effective for selected patients with multifocal hepatocellular carcinoma, the combination of resection and intraoperative RFA widens the applicability of surgical intervention for the disease.

Direct current combined with bipolar radiofrequency ablation: an ex vivo feasibility study

The combination of radiofrequency ablation (RFA) with direct current (DC) is a promising strategy to improve the efficiency of RFA. However, DC-enhanced monopolar RFA is limited by electrolytic injury at the positive-electrode site. The aim of this study was to investigate the feasibility of the DC-enhanced bipolar RFA. To obviate the need for the subcutaneous positive electrode, the DC circuit was combined with a commercially available bipolar RFA system, in which both poles of the DC circuit are connected to a single RF probe. DC was applied for 15 min and followed by RFA in bovine livers using the following various DC currents: (1) no DC (control), (2) 3V continued until the end of RFA, (3) 5V continued until the end of RFA, (4) 10V continued until the end of RFA, (5) 5V continued in the circuit with reversed pole, (6) 3V stopped after initiation of RFA, and (7) 5V stopped. Coagulation volume, temperatures at a distance of 5, 10, and 15 mm from the RF probe, mean amperage, ablation duration, applied energy, minimum impedance, and degree of tissue charring were assessed and compared (analysis of variance, Student-Newman-Keuls test). All combined DC and RFA groups did increase coagulation volume. The 10V continued group showed significantly lower applied energy, shortest ablation duration, highest minimum impedance, and highest degree of charring with the lowest coagulation volume (p<0.05). DC-enhanced bipolar RFA with both poles of the DC circuit on a single probe appears to be ineffective.

Optimization of direct current-enhanced radiofrequency ablation: an ex vivo study

The purpose of this study was to investigate the optimal setting for radiofrequency (RF) ablation combined with direct electrical current (DC) ablation in ex vivo bovine liver. An electrical circuit combining a commercially available RF ablation system with DC was developed. The negative electrode of a rectifier that provides DC was connected to a 3-cm multitined expandable RF probe. A 100-mH inductor was used to prevent electrical leakage from the RF generator. DC was applied for 15 min and followed by RF ablation in freshly excised bovine livers. Electric current was measured by an ammeter. Coagulation volume, ablation duration, and mean amperage were assessed for various DC voltages (no DC, 2.2, 4.5, and 9.0 V) and different RF ablation protocols (stepwise increase from 40 to 80 W, 40 W fixed, and 80 W fixed). Results were compared using Kruskal-Wallis and Mann-Whitney U test. Applying DC with 4.5 or 9.0 V, in combination with 40 W fixed or a stepwise increase of RF energy, resulted in significantly increased zone of ablation size compared with 2.2 V or no DC (P = 0.009). At 4.5 V DC, the stepwise increase of RF energy resulted in the same necrosis size as a 40 W fixed protocol (26.6 +/- 3.9 vs. 26.5 +/- 4.0 ml), but ablation duration was significantly decreased (296 +/- 85 s vs. 423 +/- 104 s; P = 0.028). Mean amperage was significantly lower at 4.5 V compared with 9.0 V (P = 0.028). Combining a stepwise increase of RF energy with a DC voltage of 4.5 V is most appropriate to increase coagulation volume and to minimize procedure time.

Optimizing electrode placement using finite-element models in radiofrequency ablation treatment planning

Conventional radiofrequency ablation (RFA) planning methods for identifying suitable electrode placements typically use geometric shapes to model ablation outcomes. A method is presented for searching electrode placements that couples finite-element models (FEMs) of RFA together with a novel optimization strategy. The method was designed to reduce the need for model solutions per local search step. The optimization strategy was tested against scenarios requiring single and multiple ablations. In particular, for a scenario requiring multiple ablations, a domain decomposition strategy was described to minimize the complexity of simultaneously searching multiple electrode placements. The effects of nearby vasculature on optimal electrode placement were also studied. Compared with geometric planning approaches, FEMs could potentially deliver electrode placement plans that provide more physically meaningful predictions of therapeutic outcomes.

Histopathologic and immunohistochemical features of tissue adherent to multitined electrodes after RF ablation of liver malignancies can help predict local tumor progression: initial results

PURPOSE

To determine whether histopathologic and immunohistochemical features of tissue adherent to electrodes after radiofrequency (RF) ablation of liver malignancies can help predict local tumor progression (LTP).

MATERIALS AND METHODS

Institutional review board waiver and informed consent were obtained. Histologic and immunohistochemical examinations of tissue adherent to electrodes after RF ablation of liver malignancies were performed, with application of proliferation (Ki-67) and apoptosis (caspase-3) markers. Clinical and technical information were prospectively collected for an HIPAA-registered database. Medical records and imaging were reviewed to determine LTP for treated tumors smaller than 5 cm in diameter. LTP-free and survival rates were assessed with Kaplan-Meier method; differences between groups assessed with permutation log-rank test. Multivariate analysis assessed with Cox regression for factors related to LTP.

RESULTS

Sixty-eight malignant tumors treated with RF ablation were identified. Fifty-five tissue specimens were classified as coagulation necrosis (CN), thermal artifact only, or tumor cells positive for caspase-3/negative for Ki-67; and 13 as viable tumor cells (Ki-67 positive). Mean tumor size was larger in viable (3.4 cm) than in CN (2.5 cm) group before treatment (P = .01). For viable and CN groups, LTP occurred in 12 (92%) of 13 and 16 (29%) of 55 specimens, respectively; 1-year LTP-free rates were 0% and 74%, respectively (P < .001). Multivariate analysis confirmed that viable cells comprise independent risk factor for LTP (P < .001). The odds of LTP is six times greater in viable group compared with CN group for tumors 3-5 cm (hazard ratio: 5.9, 95% confidence interval: 2.4, 14.5) and 10 times greater for tumors smaller than 3 cm (hazard ratio: 10.1, 95% confidence interval: 1.7, 57.5). Median survival was 32.7 months.

CONCLUSION

Evidence of Ki-67-positive tumor cells on the electrode after hepatic RF ablation is an independent predictor of LTP.

Is radiofrequency ablation the treatment of choice for patients with small hepatocellular carcinoma?

Liver resection is widely considered the mainstay of curative therapy for small hepatocellular carcinoma (HCC). Radiofrequency ablation (RFA) was initially developed as a treatment for small HCC in patients with considerable cirrhosis and inadequate liver function reserve for liver resection. However, in some centers, RFA is now used for small HCC, as an alternative to liver resection or even as the preferred treatment. This Practice Point commentary discusses the findings and limitations of a retrospective cohort study by Livraghi et al. that analyzed the outcomes of a group of patients with small, single HCC who underwent treatment with RFA. The authors reported a low major complication rate and a local complete response rate similar to that after resection. This commentary highlights the issues to consider when interpreting and generalizing these results, in particular that these findings need to be interpreted in the light of studies that suggest a high rate of local recurrence and incomplete histopathological response after RFA of small HCC.

Ferucarbotran expands area treated by radiofrequency ablation in rabbit livers

BACKGROUND AND AIM

Several studies have examined the factors involved with expansion of the coagulation volume following radiofrequency ablation (RFA). Ferucarbotran contains superparamagnetic iron oxide that generates heat in a radiofrequency electric field and may have an effect on the area affected by RFA. We attempted to determine whether ferucarbotran administration expands radiofrequency-ablated volume using a rabbit model.

METHODS

A total of 15 male Japanese white rabbits (16 weeks old) were used and divided into three groups of five each. A 1-mL saline solution was given intravenously into a dorsal ear vein in the control group, whereas 1 mL ferucarbotran solution (0.016 mL/kg bodyweight) was given to the common-dose group and 1 mL of a twofold concentrated ferucarbotran solution (0.032 mL/kg bodyweight) was given to the high-dose group. RFA was performed with a cool-tip electrode 4 h after the administration and immediately thereafter the rabbits were killed, and the volume of the ablated area measured using magnetic resonance imaging (MRI). Following the MRI analysis, the rabbit's livers were resected, and the maximum short axis diameter of the ablated area in each was measured.

RESULTS

None of the rabbits died during the RFA procedure. The volume of the ablated area estimated on MR images in the ferucarbotran-administered groups was larger than that in the control group. Further, our macroscopic assessment showed that the maximum short axis diameter had a tendency to increase with ferucarbotran administration.

CONCLUSION

Ferucarbotran may expand the area treated by RFA.

Microwave liver ablation: influence of hepatic vein size on heat-sink effect in a porcine model

PURPOSE

To determine influence of hepatic vein size on perfusion-mediated attenuation in adjacent microwave thermal ablation.

MATERIALS AND METHODS

With approval of the institutional animal research committee, seven Yorkshire pigs underwent percutaneous (n = 2) or open (n = 5) microwave liver ablation under general anesthesia. In each, multiple ultrasound-guided, nonoverlapping thermal lesions were created within 1 cm of hepatic veins in a 5-10-minute ablation at 45 W. After euthanasia, the liver was harvested and sectioned at 0.5-cm intervals and the degree of perivascular coagulation attenuation was graded on histopathologic analysis. Correlation between venous size (small, < or =3 mm; medium, 3-6 mm; and large, >6 mm) and attenuation grade was performed with use of the Spearman rank test.

RESULTS

In 63 of 103 sections (61%)--29 of 37 (78%) small, 27 of 48 (56%) medium, and seven of 18 (39%) large veins--the thermal injury extended to the vein wall around the entire circumference of the coagulation front without distortion of the ablation margin. In 40 of 103 sections (38.9%), varying degrees of concave distortion of perivenous ablation margins were noted, with significant correlation between vein size and heat-sink extent (P < .01). However, thermal injury extended to the vascular wall in all sections without complete circumferential sparing of liver tissue. Around two thrombosed veins, thermal lesions encased the vessels, producing paradoxically convex ablation margins.

CONCLUSIONS

Although the heat-sink effect was significantly dependent on hepatic vein size, the majority of pathologic sections exhibited no or minimal effect. Further study is required to assess clinical implications.

Analysis of recurrence pattern and its influence on survival outcome after radiofrequency ablation of hepatocellular carcinoma

BACKGROUND

Radiofrequency ablation (RFA) is an effective local ablation therapy for hepatocellular carcinoma (HCC) with favorable long-term outcome. There is no data on the analysis of recurrence pattern and its influence on long-term survival outcome after RFA in HCC patients.

AIM OF STUDY

To evaluate the tumor recurrence pattern and its influence on long-term survival in patients with HCC treated with RFA.

PATIENTS AND METHODS

From April 2001 to January 2005, 209 patients received RFA using internally cooled electrode as the sole treatment modality for HCC. Among them, 117 patients (56%) had unresectable HCC because of bilobar disease, poor liver function, and/or high medical risk for resection; whereas 92 patients (44%) underwent RFA as the primary treatment for small resectable HCC. The ablation procedure was performed through percutaneous (n=101), laparoscopic (n=17), or open approaches (n=91). The tumor recurrence pattern and long-term survival were analyzed. Multivariate analysis was carried out to identify independent prognostic factors affecting the overall survival of patients.

RESULTS

The mortality and morbidity rates were 0.9 and 15.7%, respectively. Complete tumor ablation was achieved in 192 patients (92.7%). With a median follow-up period of 26 months, local recurrence occurred in 28 patients (14.5%). Same segment and different segment intrahepatic recurrence occurred in 30 patients (15.6%) and 78 patients (40.6%), respectively. Twenty patients (10.4%) developed distant extrahepatic metastases. The overall 1-, 3-, and 5-year survival rates were 87.2, 66.6, and 42%, respectively. Different segment intrahepatic recurrence and distant recurrence after RFA carried significant poor prognostic influence on overall survival outcome. Using multivariate analysis, Child-Pugh grade (risk ratio [RR]=2.918, 95% confident interval [CI] 1.704-4.998, p=0.000), tumor size (RR=1.231, 95% CI 1.031-1.469, p=0.021), and pattern of recurrence (risk ratio [RR]=1.464, 95% CI 1.156-1.987, P=0.020) were identified as independent prognostic factors for overall survival.

CONCLUSION

The tumor recurrence pattern after RFA carries significant prognostic value in relation to overall survival. Long-term regular surveillance and aggressive treatment strategy are required for patients with different segment intrahepatic recurrence to optimize the benefits of RFA.

Characterization of tracked radiofrequency ablation in phantom

In radiofrequency ablation (RFA), successful therapy requires accurate, image-guided placement of the ablation device in a location selected by a predictive treatment plan. Current planning methods rely on geometric models of ablations that are not sensitive to underlying physical processes in RFA. Implementing plans based on computational models of RFA with image-guided techniques, however, has not been well characterized. To study the use of computational models of RFA in planning needle placement, this work compared ablations performed with an optically tracked RFA device with corresponding models of the ablations. The calibration of the tracked device allowed the positions of distal features of the device, particularly the tips of the needle electrodes, to be determined to within 1.4 +/- 0.6 mm of uncertainty. Ablations were then performed using the tracked device in a phantom system based on an agarose-albumin mixture. Images of the sliced phantom obtained from the ablation experiments were then compared with the predictions of a bioheat transfer model of RFA, which used the positional data of the tracked device obtained during ablation. The model was demonstrated to predict 90% of imaged pixels classified as being ablated. The discrepancies between model predictions and observations were analyzed and attributed to needle tracking inaccuracy as well as to uncertainties in model parameters. The results suggest the feasibility of using finite element modeling to plan ablations with predictable outcomes when implemented using tracked RFA.

A Newly Developed Perfused Umbrella Electrode for Radiofrequency Ablation: An Ex Vivo Evaluation Study in Bovine Liver

The purpose of this study was to evaluate the effectiveness of a newly developed perfused monopolar radiofrequency (RF) probe with an umbrella-shaped array. A perfused umbrella-shaped monopolar RF probe based on a LeVeen electrode (Boston Scientific Corp., Natick, MA, USA) with a 3-cm array diameter was developed. Five different configurations of this electrode were tested: (a) perfusion channel/endhole, (b) perfusion channel/endhole + sideholes, (c) 1 cm insulation removed at the tip, (d) 1 cm insulation removed at the tip + perfusion channel/endhole, and (e) 1 cm insulation removed at the tip + perfusion channel/endhole + sideholes. An unmodified LeVeen electrode served as a reference standard. RF ablations were performed in freshly excised bovine liver using a commercial monopolar RF system with a 200-W generator (RF 3000; Boston Scientific Corp.). Each electrode was tested 10 times applying the vendor's recommended ablation protocol combined with the preinjection of 2 ml 0.9% saline. Volumes and shapes of the lesions were compared. Lesions generated with the original LeVeen electrode showed a mean volume of 12.74 +/- 0.52 cm(3). Removing parts of the insulation led to larger coagulation volumes (22.65 +/- 2.12 cm(3)). Depending on the configuration, saline preinjection resulted in a further increase in coagulation volume (25.22 +/- 3.37 to 31.28 +/- 2.32 cm(3)). Besides lesion volume, the shape of the ablation zone was influenced by the configuration of the electrode used. We conclude that saline preinjection in combination with increasing the active tip length of the umbrella-shaped LeVeen RF probe allows the reliable ablation of larger volumes in comparison to the originally configured electrode.

High serum vascular endothelial growth factor levels predict poor prognosis after radiofrequency ablation of hepatocellular carcinoma: importance of tumor biomarker in ablative therapies

BACKGROUND

Radiofrequency ablation (RFA) is a recently developed treatment for hepatocellular carcinoma (HCC). Thus far, the prognostic impact of tumor biomarkers has not been evaluated in this treatment. High serum level of vascular endothelial growth factor (VEGF) has been shown to predict microscopic vascular invasion and metastasis in HCC. This study investigated the prognostic significance of pre-treatment serum VEGF level in patients with HCC undergoing RFA treatment.

METHODS

Serum VEGF levels were measured using enzyme-linked immunosorbent assay in 120 patients with HCC undergoing RFA, and in 15 healthy controls. Serum VEGF levels were correlated with clinicopathological features of the HCC patients. The prognostic significance of serum VEGF levels was assessed by univariate and multivariate analyses.

RESULTS

The median serum VEGF level in the HCC patients was 240 pg/mL (range 17-1162), significantly higher than that of healthy controls (p = .024). The serum VEGF levels were significantly correlated with platelet counts (r = .487, p < .001) but not other clinicopathological features. Patients with serum VEGF level > 240 pg/mL had worse overall and recurrence-free survival compared with those with serum VEGF level > 240 pg/mL (p = .005 and .002, respectively). By multivariate analysis, serum VEGF level was a significant prognostic factor of both overall and recurrence-free survival.

CONCLUSIONS

High pre-treatment serum VEGF levels predict poor prognosis after RFA of HCC. This study highlights the importance of tumor biomarker as a prognostic predictor in ablative therapy for HCC, which has an intrinsic problem of unavailability of histopathological prognostic features.

Current status of sonographically guided radiofrequency ablation techniques

OBJECTIVE

The purpose of this article was to review the current clinical applications of sonographically guided radiofrequency ablation (RFA) techniques.

METHODS

Publications regarding RFA extracted from a computerized database (MEDLINE) and from references cited in these articles were reviewed to evaluate the clinical effect and patient outcome.

RESULTS

Radiofrequency ablation has shown some promising effects in the treatment of tumors in various parts of the body. The recent advances in RFA technology enable larger volumes of treatment and make RFA clinically practical. It is most often used for hepatic and renal tumors, and applications for other organs and structures are increasing and rapidly developing. Sonography provides a convenient way to guide and monitor the procedure in most situations.

CONCLUSIONS

Effectiveness of RFA in the treatment of tumors in various body parts has been achieved. Radiofrequency ablation should be considered as an alternative or complementary method in the integration of oncologic management to obtain the greatest benefit to patients.

A cost-utility analysis of treatments for malignant liver tumours: a pilot project

BACKGROUND

Hepatic resection is the standard treatment for colorectal liver metastases when feasible. Techniques such as radiofrequency ablation (RFA) have been the subject of ongoing research in hopes of achieving a similar survival to that achieved with hepatic resection, but with less morbidity and better quality of life (QOL). The aim was to to generate a hypothesis concerning the cost-utility of various treatments that may be further tested with randomized trials in the future.

PATIENTS AND METHODS

This was a prospective, non-randomized pilot study comparing the cost-utility of hepatic resection, RFA, systemic chemotherapy, and symptom control alone for colorectal liver metastases. All patients with newly diagnosed liver malignancies were eligible. QOL was measured serially with the Health Utilities Index. Costs, in 2001 Canadian dollars, were captured from the viewpoint of society in general.

RESULTS

In all, 40 patients were enrolled in the study: 7 underwent hepatic resection, 7 underwent RFA (sometimes in combination with resection), 20 received systemic chemotherapy, and 6 received symptom control alone. Liver resection appeared to be the most effective approach, with an average benefit of 2.58 QALYs (quality-adjusted life years) compared with 1.95 QALYs for RFA, 1.18 QALYs for chemotherapy, and 0.82 QALYs for symptom control alone, resulting in cost-utility ratios of $7792, $8056, $12,571, and $4788 per QALY, respectively.

DISCUSSION

The cost-utility of hepatic resection and RFA appeared similar even though patients receiving RFA had more advanced disease. The role of RFA is still being defined; however, if long-term survival proves to be promising, then this study lends support to the conduct of randomized controlled trials in the future.

Liver transplantation for solitary hepatocellular carcinoma less than 3 cm in diameter in Child A cirrhosis

Liver transplantation for hepatocellular carcinoma (HCC) is the treatment of choice for patients with unresectable tumors within the Milan criteria associated with Child B or C cirrhosis. Liver transplantation provides the best cure for both the HCC and the underlying cirrhosis. In recent years, some authors have advocated liver transplantation even for resectable early HCC associated with Child A cirrhosis, leading to a controversy of whether resection or transplantation should be the first-line therapy for patients with small HCC in Child A cirrhosis. Recent studies comparing liver resection and transplantation for early HCC demonstrated similar long-term survival of 60-70%, but liver transplantation is associated with a lower tumor recurrence rate. However, the current shortage of deceased donor liver grafts limits the applicability of liver transplantation for HCC. The use of live donor liver transplantation for patients with a small solitary HCC in Child A cirrhosis that is resectable may not be justified ethically because of the potential risk to the donors. Patients put on a transplantation waiting list run a significant risk of tumor progression and dropout, while liver resection is immediately applicable to all. Advocating primary liver transplantation for patients with early HCC associated with compensated cirrhosis will increase the waiting time for transplantation and further increases the chance of dropout. Resection first and salvage transplantation for recurrent tumors or liver failure is an alternative strategy that may reduce the use of liver grafts. However, the long-term survival result of such a strategy compared with primary liver transplantation remains unclear.

Radiofrequency ablation for hepatocellular carcinoma and metastatic liver tumors: a comparative study

BACKGROUND

This study compared the effectiveness of radiofrequency ablation (RFA) for hepatocellular carcinoma (HCC) and liver metastases.

METHODS

We compared the outcomes of 240 patients with HCC and 44 patients with liver metastases treated with RFA. Data were prospectively collected and retrospectively analyzed. Effects of different variables on recurrences were studied.

RESULTS

A total of 406 tumor nodules were treated. The median size of the largest ablated tumor was 2.5 cm, and the median tumor number was 1. Complete tumor ablation was achieved in 91.2%. Local recurrence rate was 15.4% after a median follow-up of 24.5 months. There was no significant impact of tumor pathology on local recurrence. However, patients with liver metastasis had higher extrahepatic recurrence rate (P = 0.019) and shorter disease-free survival (P = 0.007). Patients with multiple tumors had higher local (P = 0.047) and extrahepatic (P = 0.019) recurrence rates than those with a solitary tumor. Tumor size had an impact on local recurrence rate only in patients with liver metastasis with a higher rate in those with tumor > 2.5 cm in diameter (P = 0.028).

CONCLUSIONS

Tumor pathology does not appear to have a significant impact on local recurrence rates. RFA is effective in local tumor control for both HCC and liver metastasis.

Radiofrequency ablation of lymphoma

Percutaneous minimally invasive radiofrequency (RF) ablation has not been described for lymphoma. This image-guided modality is presented in 3 different settings for the treatment of refractory lymphoma. The first patient received RF ablation for the curative treatment of a solitary residual hepatic mass following rituximab-based chemotherapy for a posttransplantation lymphoproliferative disorder (PTLD) and is disease-free 4 years later. The second patient received RF ablation for successful palliation of progressive follicular lymphoma adjacent to the bladder wall following chemotherapy and maximum radiation. The third patient received RF ablation for prevention of airway obstruction from progressive diffuse large B-cell lymphoma of the right neck following chemotherapy and maximum radiation. RF ablation may be clinically beneficial and should be considered for the treatment of local lymphoma that is refractory or not amenable to standard approaches.

Management of hepatic metastases from colorectal cancer

The majority of hepatic metastases in the United States occur in patients with a primary colorectal malignancy. Advances in technology combined with increasing surgeon experience have broadened the treatment options available for hepatic metastases from colorectal cancer. Surgical resection is the most effective therapy for metastatic colorectal cancer isolated to the liver. The aim of this article is to discuss the role of locally aggressive treatment options including resection, ablation, and regional chemotherapy in the management of patients with metastases from colorectal cancer.