Evaluation of liver parenchymal pressure and portal endothelium damage during radio frequency ablation in an in vivo porcine model.

BACKGROUND/AIMS: We previously developed a multi-step, incremental expansion method (multi-step method) for radio frequency ablation (RFA) in vitro, which prevented increases in pressure and reduced the ablation time as compared with other methods. In this study, we evaluated liver parenchymal pressure and portal endothelium damage during RFA with different devices and protocols in an in vivo porcine model. METHOD: Nine healthy female pigs were anaesthetized. RFA was performed with two different devices and protocols; one involved the use of a LeVeen needle with a single-step full expansion method or a multi-step method, and the other used a cool-tip needle with 40 or 60 W power. We measured the pressure in the liver parenchyma and the gallbladder during RFA. We also evaluated portal endothelium damage by NADH staining. RESULTS: The multi-step method with the LeVeen electrode resulted in the lowest parenchymal and intra-gallbladder pressures (multi-step method相似文献   

A multi-step, incremental expansion method for radio frequency ablation: optimization of the procedure to prevent increases in intra-tumor pressure and to reduce the ablation time.

BACKGROUND/AIMS: Radio frequency ablation (RFA) has been accepted clinically as a useful local treatment for hepatocellular carcinoma (HCC). However, intra-hepatic recurrence after RFA has been reported. We initially hypothesized that recurrence was attributable to increases in intra-tumor pressure during RFA, and we subsequently measured the pressure and optimized the procedure. METHODS: A block of pig liver sealed in a rigid plastic case was used as a model of an HCC tumor with a capsule. We compared the pressure between a single-step full expansion of the needle (single-step method) and incremental, stepwise expansion (multi-step method), and evaluated the effect of varying the electrical power. Finally, we performed a preliminary comparison of the ablation times for these methods in HCC cases. RESULTS: The multi-step method resulted in a significantly lower pressure and shorter total ablation time than the single-step method. Furthermore, incremental expansion in 10 steps resulted in a lower pressure and shorter ablation time than four steps. Seventy W-ablation resulted in a lower pressure and shorter time than 30- or 50 W-ablation. In HCC cases, the multiple-step method had a significantly shorter ablation time than the single-step method. CONCLUSION: The multi-step method can be recommended to reduce the ablation time, and suppress the increase in pressure.     

Scattered and rapid intrahepatic recurrences after radio frequency ablation for hepatocellular carcinoma

AIM: To evaluate a series of patients with hepatocellular carcinoma (HCC) treated with several different protocols and devices. METHODS: We treated 138 patients [chronic hepatitis/ liver cirrhosis (Child-Pugh A/B/C), 3/135 (107/25/3)] with two different devices and protocols: cool-tip needle [initial ablation at 60 W (standard method) (n = 37) or at 40 W (modified method) (n = 28)] or; ablation with a LeVeen needle using a standard single-step, full expansion (single-step) method (n = 39) or a multi-step, incremental expansion (multi-step) method. RESULTS: Eleven patients experienced rapid and scattered recurrences 1 to 7 mo after the ablation. Nine patients were treated by the cool-tip original protocol (60 W) (9/37 = 24%) and the other two by the LeVeen single-step method (2/39 = 5%). The location of the recurrence was surrounding and limited to the site of ablation segment in three cases, and spread over one lobule or both lobules in the other eight cases. There was no recurrence in the patients treated with the modified cool-tip modified method (40 W) or the LeVeen multi-step method. CONCLUSION: There is a risk of rapid and scattered recurrence after RFA, especially when the standard cool-tip procedure is used. Because such recurrence would worsen the prognosis, we recommend that modified protocols for the cool-tip and LeVeen needle methods should be used in clinical practice.     

Therapeutic effectiveness of echo-guided percutaneous radiofrequency ablation therapy with a LeVeen needle electrode in hepatocellular carcinoma

AIM:To investigate the results of radiofrequencyablation(RFA)in obtaining the necrosis of hepatocellularcarcinoma(HCC)in cirrhotic patients and to assessthe results of RFA in relation to recurrence of HCC andsurvival of the treated patients.METHODS:Fifty-six consecutive cirrhotic patients with63 HCCs were treated with RFA between May 2000 andMay 2004.The diameter of the HCCs ranged from 1 cmto 5 cm(mean 2.8 cm).In all cases RFA was performedwith percutaneous approach under ultrasound guidanceusing expandable needle electrode(LeVeen needle).Treatment efficacy and recurrence were evaluated withdual-phase spiral computed tomography(CT).RESULTS:Complete necrosis after single or multipletreatment was achieved in 96.8%(61/63)tumors.We observed recurrence after complete necrosis in 23patients(41%)during a mean follow-up of 32.3 months.The recurrences were local in 2 patients(8.6%)and indifferent segments in 21(91.4%).Major complicationsoccurred in 3 patients(4%).During follow-up period,32(57.1%)patients died;15 due to progression of HCC,11 from liver failure,3 from esophageal varices bleedingand 3 from the causes not related to liver disease.CONCLUSION:RFA with LeVeen needle is an effectiveand safe treatment for HCC<5 cm in cirrhotic patients.It has yet to be established how far this treatmentinfluences the survival rate of patients.It becomesimportant to establish treatments to prevent recurrencesin different segments,such as interferon therapy.     

Comparative study of shear wave velocities using acoustic radiation force impulse technology in hepatocellular carcinoma: the extent of radiofrequency ablation

Background/Aims

The purpose of this study was to assess the value of acoustic radiation force impulse (ARFI) for predicting the extent of radiofrequency ablation (RFA) in hepatocellular carcinoma (HCC) by correlating the elasticity of HCC and peritumoral parenchyma (as measured by ARFI) with the extent of ablation determined by computed tomography (CT).

Methods

From September 2009 to June 2011, 158 patients underwent RFA ablation for HCC (single, ≤3 cm). We evaluated the data of a total of 38 prospectively enrolled patients who underwent both ARFI imaging and contrast-enhanced CT after one session of 12 minutes of RFA without a change in needle position. The ARFI imaging indices, including the mean shear wave velocity (SWV) of HCC, mean SWV of the peritumoral parenchyma and tumor size, were evaluated to determine the statistical correlation with RFA extent after one session of 12 minutes of RFA.

Results

A stiffer liver parenchyma in patients with cirrhosis results in a smaller ablation zone.

Conclusions

SWV of ARFI in liver parenchyma was well correlated with RFA extent. After evaluating the correlation between ARFI and RFA extent, we suggest that the SWV in liver parenchyma might be a non-invasive supplementary tool for predicting the extent of RFA.     

New ablation procedure for a radiofrequency liver tissue coagulation system using an expandable needle

Objective: The stepwise hook extension technique for an expandable needle, which we reported previously, allowed roll‐off in short time with low power. The aim of this study was to investigate experimentally the efficacy of a modified extension procedure. Methods: Three pigs underwent 10 radiofrequency ablation (RFA) procedures using the 10‐hook electrode of LeVeen needle. The conventional technique was used in five RFA (group 1; the electrode was deployed in four steps to full extension), while the new technique was used in the other five RFA (group 2; the electrode was closed after the same three steps as group 1 and then fully extended). Results: The shape of the RFA‐induced zone was cone‐like or irregular in group 1 and oval‐like in group 2. The diameter vertical to the shaft was larger in group 2 (37, range 33–42 mm) than in group 1 (23, range 20–29 mm). The median ablation time was longer in group 2 (10 min 13 s) than in group 1 (3 min 56 s). Although the required energy was higher in group 2 than in group 1, that per volume was comparable between the groups (median 0.9 vs. 1.4 kJ/mm³). Conclusions: Our new procedure requires a longer session but produces larger necrosis of a uniform ellipsoid volume, making it potentially suitable for tumours more than 3 cm in diameter.     

Radiofrequency ablation of small hepatocellular carcinoma with intravenous pegylated liposomal doxorubicin

Purpose  

Synergy between radiofrequency ablation (RFA) and chemotherapy was demonstrated for liver malignancy. We assess the efficacy of intravenous pegylated liposomal doxorubicin (PLD) for RFA in patients with small hepatocellular carcinoma (HCC).     

Tolerance of radiofrequency ablation by patients of hepatocellular carcinoma

Background

Radiofrequency ablation (RFA) is currently an effective method for ablation of hepatocellular carcinoma (HCC). Early reports have indicated that RFA is safe and virtually free from major complications. Unlike partial hepatectomy for HCC on patients with cirrhosis, there are no data on the safety limit of RFA. However, information is vital for selection of appropriate patients for the procedure. In this study, we analyzed results from use of RFA on HCC patients and determined the lower limit of liver function with which HCC patients can tolerate RFA.

Method

Preoperative variables of 310 patients who underwent RFA for HCC were analyzed to identify the risk factors in RFA intolerance in terms of morbidity associated with stress-induced complications.

Results

Thirty-nine (12.6%) patients developed intolerance of RFA. Postoperative morbidity was mainly because of intractable ascites (n = 13), hyperbilirubinemia (n = 10), massive pleural effusion (n = 7), and other complications (n = 14). Multivariate analysis revealed that serum albumin level (P = 0.001), serum bilirubin level (P = 0.000), tumor number (P = 0.002), and RFA duration (P = 0.017) all played a role in this issue.

Conclusions

Simple data such as serum bilirubin, serum albumin level, and tumor number can be used to predict HCC patients’ tolerance of RFA. Avoidance of excessive RFA time and careful monitoring of patients at risk are important means of reducing the postoperative morbidity rate.     

Radiofrequency ablation in a porcine liver model： Effects of transcatheter arterial embolization with iodized oil on ablation time, maximum output, and coagulation diameter as well as angiographic characteristics

AIM:To evaluate the effects of combined radiofrequen-cy ablation and transcatheter arterial embolization with iodized oil on ablation time,maximum output,coagula-tion diameter,and portal angiography in a porcine liver model. METHODS: Radiofrequency ablation (RFA) was applied to in vivo livers of 10 normal pigs using a 17-gauge 3.0 cm expandable LeVeen RF needle electrode with or with-out transcatheter arterial embolization (TAE) with iodized oil (n = 5). In each animal,2 areas in the liver were ab-lated. Direct portography was performed before and af-ter RFA. Ablation was initiated at an output of 30 W,and continued with an increase of 10 W per minute until roll-off occurred. Ablation time and maximum output until roll-off,and coagulated tissue diameter were compared between the 2 groups. Angiographic changes on portog-raphy before and after ablation were also reviewed. RESULTS: For groups with and without TAE with iodized oil,the ablation times until roll-off were 320.6 ± 30.9 seconds and 445.1 ± 35.9 seconds,respectively,maxi-mum outputs were 69.0 ± 7.38 W and 87.0 ± 4.83 W and maximal diameters of coagulation were 41.7 ± 3.85 mm and 33.2 ± 2.28 mm. Significant reductions of abla-tion time and maximum output,and significantly larger coagulation diameter were obtained with RFA following TAE with iodized oil compared to RFA alone. Portography after RFA following TAE with iodized oil revealed more occlusion of the larger portal branches than with RFA alone. CONCLUSION: RFA following TAE with iodized oil can increase the volume of coagulation necrosis with lower output and shorter ablation time than RFA alone in nor-mal pig liver tissue.     

Comparison of Internally Cooled Wet Electrode and Hepatic Vascular Inflow Occlusion Method for Hepatic Radiofrequency Ablation

Background/Aims

Various strategies to expand the ablation zone have been attempted using hepatic radiofrequency ablation (RFA). The optimal strategy, however, is unknown. We compared hepatic RFA with an internally cooled wet (ICW) electrode and vascular inflow occlusion.

Methods

Eight dogs were assigned to one of three groups: only RFA using an internally cooled electrode (group A), RFA using an ICW electrode (group B), and RFA using an internally cooled electrode with the Pringle maneuver (group C). The ablation zone diameters were measured on the gross specimens, and the volume of the ablation zone was calculated.

Results

The ablation zone volume was greatest in group B (1.82±1.23 cm³), followed by group C (1.22±0.47 cm³), and then group A (0.48±0.33 cm³). The volumes for group B were significantly larger than the volumes for group A (p=0.030). There was no significant difference in the volumes between groups A and C (p=0.079) and between groups B and C (p=0.827).

Conclusions

Both the usage of an ICW electrode and hepatic vascular occlusion effectively expanded the ablation zone. The use of an ICW electrode induced a larger ablation zone with easy handling compared with using hepatic vascular occlusion, although this difference was not statistically significant.     

Meta-analysis of radiofrequency ablation versus hepatic resection for small hepatocellular carcinoma

Background  

There is no clear consensus on the better therapy [radiofrequency ablation (RFA) versus hepatic resection (HR)] for small hepatocellular carcinoma (HCC) eligible for surgical treatments. This study is a meta-analysis of the available evidence.     

Successful cryothermal ablation for Atrioventricular nodal reentry tachycardia after radiofrequency ablation failure

Background  

Catheter ablation is the preferred management approach for atrioventricular nodal reentrant tachycardia (AVNRT). Cryothermal ablation (Cryo) and radiofrequency ablation (RFA) are the two clinically available ablation modalities. Atrioventricular (AV) block is a concerning potential complication and is commonly preceded by transient AV block or rapid junctional beats when using RFA. For challenging AVNRT cases, where RFA produced signs of impending AV block, we evaluate the application of Cryo to the same anatomical location where RFA was abandoned.     

Recurrence rates and factors for recurrence after radiofrequency ablation combined with transarterial chemoembolization for hepatocellular carcinoma: a retrospective cohort study

Purpose

There have been reports that radiofrequency ablation (RFA) combined with transarterial chemoembolization (TACE) is as equally effective as surgical resection for the treatment of hepatocellular carcinoma (HCC). This study aimed to evaluate recurrence rate and risk factor of recurrence after RFA combined with TACE for early stage HCC.

Methods

We reviewed the medical records of the patients who were diagnosed with early stage HCC between March 2006 and August 2008 at Korea University Medical Center and treated with RFA combined with TACE for curative intent (n?=?65).

Results

Recurrence rate was 40% (26 cases) and the time to recurrence was 14.9?months. Cumulative recurrence rate at 1?year was 20% (13 cases) and at 2?years was 33.8% (22 cases). Significant variables for recurrence were: (1) RFA repeated more than one session at initial therapy (P?<?0.001) and (2) size of main lesion ??2?cm (P?=?0.047).

Conclusions

The recurrence rate of combination therapy was considerably high. Regardless of the therapy used, careful post-RFA follow-up is needed, especially if additional treatment is required after the first session or if the main lesion is ??2?cm at the time of RFA.     

Prospective double-blinded randomized controlled trial of Microwave versus RadioFrequency Ablation for hepatocellular carcinoma (McRFA trial)

BackgroundMicrowave (MWA) and radiofrequency ablation are the commonly used local ablation for hepatocellular carcinoma (HCC). Studies comparing both techniques are scarce. The aim of this study was to compare the efficacy of MWA versus RFA as a treatment for HCC.MethodsPatients with HCC who were suitable for local ablation were randomized into MWA or RFA. All patients were followed up regularly with contrast-enhanced computed tomography (CT) performed at 1, 3, 6 and 12 months after ablation. Both patients and the radiologists who interpreted the post-procedure CT scans were blinded to the treatment allocation. Treatment-related morbidity, overall and disease-free survivals were analyzed.ResultsA total of 93 patients were recruited. Among them, 47 and 46 patients were randomized to MWA and RFA respectively. Patients in two groups were comparable in baseline demographics and tumor characteristics. With a median follow-up of around 30 months, there were no significant difference in the treatment-related morbidity, overall and disease-free survivals. MWA had a significantly shorter overall ablation time when compared with RFA (12 min vs 24 min, p < 0.001).ConclusionsMWA is no different to RFA with respect to completeness of ablation and survivals. It is, however, as safe and effective as RFA in treating small HCC.     

Factors for early tumor recurrence of single small hepatocellular carcinoma after percutaneous radiofrequency ablation therapy

AIM: To evaluate the factors affecting the early tumor recurrence within one year in cirrhotic patients having a single small hepatocellular carcinoma (HCC) after complete tumor necrosis by radiofrequency ablation (RFA) therapy. METHODS: Thirty patients with a single small HCC received RFA therapy by a RFA 2000 generator with LeVeen needle. Tri-phase computerized tomogram was followed every 2 to 3 mo after RFA. The clinical effects and tumor recurrence were recorded. RESULTS: The initial complete tumor necrosis rate was 86.7%. Twenty-two patients were followed for more than one year. The local and overall recurrence rates were 13.6% and 36.4%, 33.3% and 56.2%, 46.6% and 56.2% at 12, 24 and 30 mo, respectively. No major complication or procedure-related mortality was found. The risk factors for early local tumor recurrence within one year were larger tumor size, poor pathologic differentiation of tumor cells and advanced tumor staging. The age of patients with new tumor formation within one year was relatively younger (55.1±8.3 vs 66.7±10.8, P= 0.029). CONCLUSION: Large tumor size, poor pathologic differentiation of tumor cells and advanced tumor staging are the risk factors for early local tumor recurrence within one year, and young age is the positive predictor for new tumor formation within one year.     

Measurement of Intrahepatic Pressure during Microwave Ablation in an Ex Vivo Bovine Liver Model

Background/Aims

We experimented with different ablation methods and two types of microwave antennas to determine whether microwave ablation (MWA) increases intrahepatic pressure and to identify an MWA protocol that avoids increasing intrahepatic pressure.

Methods

MWA was performed using either a single-step standard ablation or a stepwise increment ablation paired with either a 16-gauge (G) 2-cm antenna or a 14G 4-cm antenna. We compared the maximum pressures and total ablation volumes.

Results

The mean maximum intrahepatic pressures and ablation volumes were as follows: 16G single-step: 37±33.4 mm Hg and 4.63 cm³; 16G multistep: 31±18.7 mm Hg and 3.75 cm³; 14G single-step: 114±45.4 mm Hg and 15.33 cm³; and 14G multistep: 106±43.8 mm Hg and 10.98 cm³. The intrahepatic pressure rose during MWA, but there were no statistically significant differences between the single and multistep methods when the same gauge antennae were used. The total ablation volume was different only in the 14G groups (p<0.05).

Conclusions

We demonstrated an increase in intrahepatic pressure during MWA. The multistep method may be used to prevent increased intrahepatic pressure after applying the proper power.     

Clinical utility of postablation liver tumor biopsy and possibility of gene mutation analysis

Aim

Radiofrequency ablation (RFA) is regarded as a first-line treatment for hepatocellular carcinoma (HCC) at an early stage. When treated with RFA, tumor biopsy may not be performed due to the risk of neoplastic seeding. We previously revealed that the risk of neoplastic seeding is significantly reduced by performing biopsies after RFA. In this study, we investigated the possibility of pathological evaluation and gene mutation analysis of post-RFA tumor specimens.

Methods

Radiofrequency ablation was undertaken on diethylnitrosamine-induced mouse liver tumor, and tumor samples with or without RFA were subjected to whole exome sequencing. Post-RFA human liver tumor specimens were used for detection of TERT promoter mutations and pathological assessment.

Results

The average somatic mutation rate, sites of mutation, and small indels and base transition patterns were comparable between the nontreated and post-RFA tumors. We identified 684 sites of nonsynonymous somatic substitutions in the nontreated tumor and 704 sites of nonsynonymous somatic substitutions in the post-RFA tumor, with approximately 85% in common. In the human post-RFA samples, the TERT promoter mutations were successfully detected in 40% of the cases. Pathological evaluation was possible with post-RFA specimens, and in one case, the diagnosis of adenocarcinoma was made.

Conclusion

Our findings suggest that post-RFA liver tumor biopsy is a useful and safe method for obtaining tumor samples that can be used for gene mutation analysis and for pathological assessment.     

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.     

Digital image analysis of endoscopic ultrasonography is helpful in diagnosing gastric mesenchymal tumors

Background

Recent studies suggest that a combination of radiofrequency ablation (RFA) and transarterial chemoembolization (TACE) may have theoretical advantages over TACE alone for treatment of hepatocellular carcinoma (HCC). The purpose of this study was to evaluate the effectiveness and safety of radiofrequency ablation following first-line TACE treatment in the management of HCC beyond the Milan Criteria.

Methods

Forty-five patients who consecutively underwent RFA following first-line TACE treatment for HCC beyond the Milan criteria were enrolled in this study. RFA was performed within 1–2 months after TACE treatment in patients who had incomplete necrotic tumor nodules. Primary effectiveness, complications, survival rates, and prognostic factors were evaluated retrospectively.

Results

Complete ablation was achieved in 76.2% of the lesions according to 1-month follow-up computed tomography/magnetic resonance imaging evaluation. The mean follow-up period was 30.9 months (range 3–94 months). There were no major complications after RFA therapy. The median overall survival was 29 months (range 20–38 months), with 1-, 2-, and 3-year survival of 89%, 61%, and 43%, respectively. Multivariate analysis revealed that tumor diameter (P?=?0.045, hazard ratio [HR]?=?0.228, 95% confidence interval [CI]: 0.054-0.968) and pretreatment serum alpha-fetoprotein level (P?=?0.024, HR?=?2.239, 95% CI: 1.114-4.500) were independent predictors for long-term survival.

Conclusions

HCC beyond the Milan criteria can be completely and safely ablated by radiofrequency ablation following first-line TACE treatment with a low rate of complications and favorable survival outcome. Further assessment of the survival benefits of combination treatment for HCCs beyond the Milan Criteria is warranted.     

Ex-vivo histopathologic examination of irrigated radiofrequency ablation utilizing half-normal saline of the human heart

Introduction

Radiofrequency ablation (RFA) utilizing half-normal saline (HNS) irrigation is a promising intervention to circumvent commonly encountered limitations during radiofrequency ablation of deep myocardial substrate. Few studies to date have analyzed the morphologic changes in the human myocardium following HNS RFA.

Methods and Results

Three patients with symptomatic ventricular tachycardia (VT) who underwent RFA with HNS irrigation underwent pathological specimen examination at time of autopsy or following native heart explant at the time of cardiac transplantation. Gross evaluation of the heart was performed fresh and after fixation in 10% formalin. A routine examination was performed with fixation in 10% formalin. Sections of lesioned tissue were paraffin embedded and evaluated using standard hematoxylin and eosin (H&E) staining.

Conclusion

Irrigated RF ablation with HNS irrigant produces coagulative necrosis as well as several delayed histopathological changes with a deeper field of effective ablation. Transmurality may not be obtained in the ventricular myocardium with endocardial, epicardial, or sequential unipolar HNS ablation.