Percutaneous tumor ablation: increased coagulation by combining radio-frequency ablation and ethanol instillation in a rat breast tumor model

Percutaneous ethanol injection enhanced the efficacy of radiofrequency ablation in the treatment of HCC: an insight into the mechanism of ethanol action

PURPOSE

To discuss the possible reasons why percutaneous intratumoral ethanol injection (PEI) combined with radiofrequency ablation (RFA) to treat hepatocellular carcinoma (HCC) reduced the recurrence and metastasis compared with RFA alone.

MATERIALS AND METHODS

Forty VX2 tumor-bearing rabbits were randomly divided into four groups (n = 10): the PEI, RFA, PEI-RFA, and control groups. Five rabbits from each group were sacrificed on the 3rd and 7th days after ablation. The number of metastatic tumors in the lung was counted. The ablation volume was measured, and residual tumor specimens were prepared for hematoxylin and eosin staining and caspase-3, Ki-67, and VEGF immunohistochemical staining.

RESULTS

The volume of ablation in the PEI-RFA group was significantly larger than that in the RFA and PEI groups (p < 0.05). However, no significant differences in the number of lung metastases after ablation were observed among the groups (p > 0.05). The number of microthrombi in the PEI-RFA group was greater than that in the control and RFA groups (p < 0.001 and p < 0.05). The Ki-67 labeling index (LI) and H-score of VEGF in the PEI-RFA group were lower than those in the RFA group, while the H-score of caspase-3 was higher than that in the RFA group on the 7th day after ablation (p < 0.05).

CONCLUSION

PEI occluded blood vessels by inducing microthrombi formation, and thereby reducing heat dissipation and increasing the effect of RFA. More importantly, in comparison with an incomplete RFA, PEI-RFA inhibited the increase in the Ki-67 and VEGF expression levels and the decrease in the caspase-3 expression level to happen at some extent and therefore improved the prognosis.

Pre-operative Assessment of Ablation Margins for Variable Blood Perfusion Metrics in a Magnetic Resonance Imaging Based Complex Breast Tumour Anatomy: Simulation Paradigms in Thermal Therapies

BACKGROUND AND OBJECTIVES

Image-guided medical interventions facilitates precise visualization at treatment site. The conformal prediction for sparing healthy tissue fringes precisely in the vicinity of irregular tumour anatomy remains clinically challenging. Pre-clinical image-based computational modelling is imperative as it helps in enhancement of treatment quality, augmenting clinical-decision making, while planning, targeting, controlling, monitoring and assessing treatment response with an effective risk assessment before the onset of treatment in clinical settings. In this study, the influence of heat deposition rate (SAR), exposure duration, and variable blood perfusion metrics for a patient-specific breast tumour is quantified considering the tumour margins thereby suggesting need of geometrically accurate models.

METHODS

A three-dimensional realistic model mimicking dimensions of a female breast, comprising ~1.7 cm irregular tumour, was generated from patient specific two-dimensional DICOM format MRI images through image segmentation tools MIMICS 19.0® and 3-Matic 11.0® which is finally exported to COMSOL Multiphysics 5.2® as a volumetric mesh for finite element analysis. The Pennes bioheat transfer model and Arrhenius thermal damage model of cell-death are integrated to simulate a coupled biophysics problem. A comparative blood perfusion analysis is done to evaluate the response of tumour during heating considering thermal damage extent, including the tumour margins while sparing critical adjoining healthy tissues.

RESULTS

The evaluated thermal damage zones for 1 mm, 2 mm and 3 mm fringe heating region (beyond tumour boundary) reveals 0.09%, 0.21% and 0.34% thermal damage to the healthy tissue (which is <1%) and thus successful necrosis of the tumour. The iterative computational experiments suggests treatment margins < 5 mm are sufficient enough as heating beyond 3 mm fringe layer leads to higher damage surrounding the tumour approximately 1.5 times the tumour volume. Further, the heat-dosage requirements are 22% more for highly perfused tumour as compared to moderately perfused tumour with an approximate double time to ablate the whole tumour volume.

CONCLUSIONS

Depending on the blood perfusion characteristics of a tumour, it is a trade-off between heat-dosage (SAR) and exposure/treatment duration to get desired thermal damage including the irregular tumour boundaries while taking into account, the margin of healthy tissue. The suggested patient-specific integrated multiphysics-model based on MRI-Images may be implemented for pre-treatment planning based on the tumour blood perfusion to evaluate the thermal ablation zone dimensions clinically and thereby avoiding the damage of off-target tissues. Thus, risks involving underestimation or overestimation of thermal coagulation zones may be minimised while preserving the surrounding normal breast parenchyma.

Efficacy and safety of percutaneous microwave ablation for hepatocellular carcinomas <4 cm in difficult location

OBJECTIVE

Tumor location is a critical factor for determining technical success and local recurrence following percutaneous ablation of hepatocellular carcinomas (HCC). The purpose of this retrospective study was to evaluate the safety and outcome measures of percutaneous microwave ablation (pMWA) for HCCs <4 cm in difficult locations.

METHODS

Retrospective review included 81 patients who underwent pMWA for HCCs <4 cm. Fourty-three patients (30 males and 13 females; mean age, 61 years) with 53 HCCs located near the diaphragm, heart, gallbladder, kidney, gastrointestinal tract, large vessel and exophytic location were included under difficult location group. Thirty-eight patients (29 males and nine females; mean age, 60 years) with 48 HCCs in other locations were included under control group. Baseline demographics were recorded. Technical efficacy, local tumor progression (LTP), and complication rates were evaluated.

RESULTS

Mean follow-up period was 3.4 months (range 1-7). There was no major complication in both the groups; two patients had a mild perihepatic hemorrhage in the difficult location group which was managed conservatively. There was no difference between the groups in the overall technical efficacy rate (84.9% vs 91.7%, p = 0.294), LTP rate (4.4% vs 2.2%. p = 0.57) or complication rate (4.6% vs 0%, p = 0.177).

CONCLUSION

Our data suggest that there is no significant difference in technical efficacy, LTP or complication rates for MWA in both difficult and normal locations.

ADVANCES IN KNOWLEDGE

With proper patient selection, pre-procedural planning and appropriate technique, pMWA is feasible, safe, and effective for small HCCs in difficult location with an acceptable range of complications.

Heat shock protein expression and autophagy after incomplete thermal ablation and their correlation

OBJECTIVE

To establish a model of incomplete ablation in nude mice with hepatocellular carcinoma (HCC) and to evaluate heat shock protein (HSP) expression and autophagy and their correlation.

MATERIALS AND METHODS

In the first stage, 12 nude mice with HCC were randomly divided into two groups (n = 6). A sham puncture operation was performed for one group, and palliative laser ablation was performed for the other group. All mice were sacrificed after 18 h, and HSP expression, autophagy, and apoptosis were assessed. In the second stage, 16 nude mice with HCC were randomly divided into two groups (n = 8). One group was given an HSP90 inhibitor before the operation, and the other group was given dimethyl sulfoxide (DMSO) as a control. HSP expression, autophagy and apoptosis were assessed for the two groups after palliative laser ablation.

RESULTS

In the incomplete ablation model, using nude mice with HCC, HSP90, HSP70, and HSP27 expression was up-regulated, Akt and mTOR phosphorylation was enhanced, autophagy was decreased, and apoptosis was increased. After administration of the HSP90 inhibitor, HSP90, P-Akt, and P-mTOR expression was decreased, autophagy was increased, and apoptosis was further increased.

CONCLUSION

Autophagy was decreased in the incomplete ablation model and might be inversely correlated with HSP expression. It is suggested that the HSP90/Akt/mTOR pathway is involved in signal transmission between autophagy and HSPs.

Combined radiofrequency ablation and ethanol injection versus repeat hepatectomy for elderly patients with recurrent hepatocellular carcinoma after initial hepatic surgery

PURPOSE

To retrospectively compare the efficacy and safety of combined radiofrequency ablation and percutaneous ethanol injection (RFA-PEI) with repeat hepatectomy for elderly patients with initial recurrent hepatocellular carcinoma (HCC) after hepatic surgery.

METHODS

From January 2009 to June 2015, 105 elderly patients (≥70 years) who underwent RFA-PEI (n = 57) or repeated hepatectomy (n = 48) for recurrent HCC ≤ 5.0 cm were included in the study. The overall survival (OS) and recurrence-free survival (RFS) were analysed with the Kaplan-Meier method and compared by the log-rank test. Non-tumour-related death, complications and hospital stays were assessed. Univariate and multivariate analyses were performed to identify the prognostic significance of the variables in predicting the OS and RFS.

RESULTS

OS rates were 78.2%, 40.8% and 36.7% at 1, 3 and 5 years after RFA-PEI and 76.3%, 52.5% and 42.6% after repeat hepatectomy, respectively (p = 0.413). Correspondingly, the 1-, 3- and 5-year RFS rates after RFA-PEI and repeat hepatectomy were 69.5%, 37.8%, 33.1% and 73.1%, 49.7%, 40.7%, respectively (p = 0.465). Non-tumour-related deaths in the RFA-PEI group (2/57) were significantly fewer than those in the repeat hepatectomy group (10/48) (p = 0.016). RFA-PEI was superior to repeat hepatectomy regarding the major complication rates and length of in-hospital stay (both p < 0.001). Multivariate analysis showed that the tumour number was the significant prognostic factor for the OS (hazard ratio (HR) = 1.961, 95% CI = 1.043-3.686, p = 0.037) and RFS (HR = 1.866, 95% CI = 1.064-3.274, p = 0.030).

CONCLUSION

RFA-PEI provides comparable OS and RFS to repeat hepatectomy for elderly patients with small recurrent HCC after hepatectomy but with fewer non-tumour-related deaths, major complications and shorter hospital stays.

Contrast-Enhanced Hepatic Sonography

Hepatic applications of sonography include evaluation of the gallbladder and bile ducts, assessment of patients with suspected portal hypertension, and evaluation of focal and diffuse parenchymal liver disease. Ultrasound imaging (US) is generally a reliable and accurate method to diagnose a variety of hepatic abnormalities; however, in some cases there is a need to improve sonography's sensitivity and specificity, particularly for the detection and characterization of hepatic masses. Recent clinical experience has shown that the addition of a US contrast agent can enhance sonography's diagnostic capabilities including improving assessments of hepatic blood flow and the detection and characterization of hepatic neoplasms. One intravenously administered US contrast agent is now available in the United States, but its approved indication is limited to echocardiographic applications. Additional agents that have more diagnostic applications are likely to become available. Contrast-enhanced sonography may play a significant role in the diagnosis and management of patients with suspected hepatic abnormalities. This article describes two generic types of US contrast agents—vascular agents and tissue-specific agents—and includes a review of recent published reports on clinical applications of contrast-enhanced hepatic sonography.

Imaging Intratumoral Nanoparticle Uptake After Combining Nanoembolization with Various Ablative Therapies in Hepatic VX2 Rabbit Tumors

Combining image-guided therapy techniques for the treatment of liver cancers is a strategy that is being used to improve local tumor control rates. Here, we evaluate the intratumoral uptake of nanoparticles used in combination with radiofrequency ablation (RFA), irreversible electroporation (IRE), or laser induced thermal therapy (LITT). Eight rabbits with VX2 tumor in the liver underwent one of four treatments: (i) nanoembolization (NE) with radiolabeled, hollow gold nanoparticles loaded with doxorubicin (⁶⁴Cu-PEG-HAuNS-DOX); (ii) NE + RFA; (iii) NE + IRE; (iv) NE +LITT. Positron emission tomography/computed tomography (PET/CT) imaging was obtained 1-hr or 18-hrs after intervention. Tissue samples were collected for autoradiography and transmission electron microscopy (TEM) analysis. PET/CT imaging at 1-hr showed focal deposition of oil and nanoparticles in the tumor only after NE+ RFA but at 18-hrs, all animals had focal accumulation of oil and nanoparticles in the tumor region. Autoradiograph analysis demonstrated nanoparticle deposition in the tumor and in the ablated tissues adjacent to the tumor when NE was combined with ablation. TEM results showed the intracellular uptake of nanoparticles in tumor only after NE + IRE. Nanoparticles demonstrated a structural change, suggesting direct interaction, potentially leading to drug release, only after NE + LITT. The findings demonstrate that a combined NE and ablation treatment technique for liver tumors is feasible, resulting in deposition of nanoparticles in and around the tumor. Depending on the ablative energy applied, different effects are seen on nanoparticle localization and structure. These effects should be considered when designing nanoparticles for use in combination with ablation technologies.

Radiofrequency ablation-combined multimodel therapies for hepatocellular carcinoma: Current status

Radiofrequency ablation (RFA) is widely accepted as a first-line interventional oncology approach for hepatocellular carcinoma (HCC) and has the advantages of high treatment efficacy and low complication risk. Local control rates equivalent to hepatic resection can be reached by RFA alone when treating small HCCs (<2 cm) in favorable locations. However, local tumor progression and recurrence rates with RFA monotherapy increase sharply when treating larger lesions (>3 cm). To address this clinical problem, recent efforts have focused on multimodel management of HCC by combining RFA with different techniques, including percutaneous ethanol injection, transarterial chemo-embolization, targeted molecular therapy, nanoparticle-mediated therapy, and immunotherapy. The combination strategy indeed leads to better outcomes in comparison to RFA alone. In this article, we review the current status of RFA-combined multimodal therapies in the management of HCC.

Combining radiofrequency ablation and ethanol injection may achieve comparable long-term outcomes in larger hepatocellular carcinoma (3.1-4 cm) and in high-risk locations

Radiofrequency ablation (RFA) is more effective for hepatocellular carcinoma (HCC) < 3 cm. Combining percutaneous ethanol injection and RFA for HCC can increase ablation; however, the long-term outcome remains unknown. The aim of this study was to compare long-term outcomes between patients with HCC of 2-3 cm versus 3.1-4 cm and in high-risk versus non-high-risk locations after combination therapy. The primary endpoint was overall survival and the secondary endpoint was local tumor progression (LTP). Fifty-four consecutive patients with 72 tumors were enrolled. Twenty-two (30.6%) tumors and 60 (83.3%) tumors were of 3.1-4 cm and in high-risk locations, respectively. Primary technique effectiveness was comparable between HCC of 2-3 cm versus 3.1-4 cm (98% vs. 95.5%, p = 0.521), and HCC in non-high risk and high-risk locations (100% vs. 96.7%, p = 1.000). The cumulative survival rates at 1 year, 3 years, and 5 years were 90.3%, 78.9%, and 60.3%, respectively, in patients with HCC of 2-3 cm; 95.0%, 84.4%, and 69.3% in HCC of 3.1-4.0 cm (p = 0.397); 90.0%, 71.1%, and 71.1% in patients with HCC in non-high-risk locations; and 92.7%, 81.6%, and 65.4% in high-risk locations (p = 0.979). The cumulative LTP rates at 1 year, 3 years, and 5 years were 10.2%, 32.6%, and 32.6%, respectively, in all HCCs; 12.6%, 33.9%, and 33.9% in HCC of 2-3 cm; 4.8%, 29.5%, and 29.5% in HCC of 3.1-4 cm (p = 0.616); 16.7%, 50.0%, and 50.0% in patients with HCC in non-high-risk locations; and 8.8%, 29.9%, and 29.9% in patients with HCC in high-risk locations (p = 0.283). The cumulative survival and LTP rates were not significantly different among the various subgroups. Combining RFA and percutaneous ethanol injection achieved comparable long-term outcomes in HCCs of 2-3 cm versus 3.1-4.0 cm and in high-risk versus non-high-risk locations. A randomized controlled or cohort studies with larger sample size are warranted.

Combined radiofrequency ablation and ethanol injection with a multipronged needle for the treatment of medium and large hepatocellular carcinoma

OBJECTIVE

To evaluate the efficacy and safety of combined radiofrequency ablation (RFA) and ethanol injection with a multipronged needle in the treatment of medium (3.1-5.0 cm) and large (5.1-7.0 cm) hepatocellular carcinoma (HCC).

METHODS

A total of 65 patients with 67 HCC nodules were enrolled in this prospective study. All of them received the treatment of combined RFA and multipronged ethanol injection percutaneously.

RESULTS

The average volume of injected ethanol was 14.4 ± 4.1 ml (range, 9-30 ml). The average number of RFA electrode insertions was 1.7 ± 0.8 (range, 1-4). The rate of initial local complete response (CR) was 94.0 % (63/67). After additional treatment, technical success was achieved in all HCC nodules. There were no treatment-related deaths, and major complications were observed in 3 (4.6%) patients. After a mean follow-up of 20.0 ± 7.6 months, local tumour progression was observed in 10 (10/67, 14.9%) tumours, whereas distant recurrence developed in 32 (32/65, 49.2%) patients. The 1-year and 2-year survival rates were 93.1% and 88.1%, respectively.

CONCLUSION

The combination of RFA and multipronged ethanol injection in the treatment of medium and large HCC is safe and effective with a high rate of local tumour control.

KEY POINTS

• Combined radiofrequency ablation and multipronged ethanol injection is a new therapeutic strategy • Treatment is safe and effective for medium and large hepatocellular carcinoma (HCC) • A multipronged needle allows for a homogeneous ethanol distribution.

Therapeutic efficacy of combining pegylated liposomal doxorubicin and radiofrequency (RF) ablation: comparison between slow-drug-releasing, non-thermosensitive and fast-drug-releasing, thermosensitive nano-liposomes

AIMS

To determine how the accumulation of drug in mice bearing an extra-hepatic tumor and its therapeutic efficacy are affected by the type of PEGylated liposomal doxorubicin used, treatment modality, and rate of drug release from the liposomes, when combined with radiofrequency (RF) ablation.

MATERIALS AND METHODS

Two nano-drugs, both long-circulating PEGylated doxorubicin liposomes, were formulated: (1) PEGylated doxorubicin in thermosensitive liposomes (PLDTS), having a burst-type fast drug release above the liposomes' solid ordered to liquid disordered phase transition (at 42°C), and (2) non-thermosensitive PEGylated doxorubicin liposomes (PLDs), having a slow and continuous drug release. Both were administered intravenously at 8 mg/kg doxorubicin dose to tumor-bearing mice. Animals were divided into 6 groups: no treatment, PLD, RF, RF+PLD, PLDTS, and PLDTS+RF, for intra-tumor doxorubicin deposition at 1, 24, and 72 h post-injection (in total 41, mice), and 31 mice were used for randomized survival studies.

RESULTS

Non-thermosensitive PLD combined with RF had the least tumor growth and the best end-point survival, better than PLDTS+RF (p<0.005) or all individual therapies (p<0.001). Although at 1 h post-treatment the greatest amount of intra-tumoral doxorubicin was seen following PLDTS+RF (p<0.05), by 24 and 72 h the greatest doxorubicin amount was seen for PLD+RF (p<0.05); in this group the tumor also has the longest exposure to doxorubicin.

CONCLUSION

Optimizing therapeutic efficacy of PLD requires a better understanding of the relationship between the effect of RF on tumor microenvironment and liposome drug release profile. If drug release is too fast, the benefit of changing the microenvironment by RF on tumor drug localization and therapeutic efficacy may be much smaller than for PLDs having slow and temperature-independent drug release. Thus the much longer circulation time of doxorubicin from PLD than from PLDTS may be beneficial in many therapeutic instances, especially in extra-hepatic tumors.

Ultrasound-guided percutaneous laser and ethanol ablation of rabbit VX2 liver tumors

BACKGROUND

Only a small percentage of patients with hepatocellular carcinoma (HCC) may benefit out of surgical resection. Thus, lots of these patients are in need of local control, such as percutaneous ethanol injection (PEI), percutaneous laser ablation (PLA), or radiofrequency thermal ablation (RF).

PURPOSE

To investigate the effects of ultrasound-guided PLA combined with PEI on rabbit VX2 liver tumors, using conventional gray-scale ultrasonography (US), color/power Doppler (CD/PD)US, contrast-enhanced (CE) US, and histologic examination.

MATERIAL AND METHODS

VX2 tumors were implanted in the livers of 80 rabbits. Fourteen days after implantation, animals were randomly separated into four groups of 20 rabbits. Treatment of the four groups was with: (i) PLA; (ii) PEI; (iii) combined therapy of PLA immediately followed by PEI; and (iv) combined therapy of PEI immediately followed by PLA. Conventional gray-scale US, CD US, PD US, and CE US were performed before and after ablation. The effects on ablated areas were assessed by histologic examination.

RESULTS

Conventional gray-scale US showed a clear boundary around the ablated area in groups 1, 3, and 4. An isoechoic treated region with an irregular boundary was seen in group 2. On CE US, coagulated areas demonstrated a perfusion defect. Both conventional gray-scale US and CE US showed that the ablated volume in group 4 was larger than that in groups 1, 2, and 3. CD US and PD US demonstrated residual tumor in the periphery of ablated areas in groups 1 and 2, but not in groups 3 and 4. CE US demonstrated no residual tumor in group 4, unlike in groups 1, 2, and 3. Examination of treated tumors demonstrated necrosis in the ablated zones and increasing surrounding fibrous bands in the four treatment groups. Residual viable tissue in group 4 was less than that in groups 1, 2, and 3.

CONCLUSION

Combined therapy of PEI immediately followed by PLA can coagulate significantly larger volumes of tumor and reduce residual tumor.

Radiofrequency ablation combined with liposomal quercetin to increase tumour destruction by modulation of heat shock protein production in a small animal model

PURPOSE

To investigate the effect of heat shock protein (HSP) modulation on tumour coagulation by combining radiofrequency (RF) ablation with adjuvant liposomal quercetin and/or doxorubicin in a rat tumour model.

METHODS

Sixty R3230 breast adenocarcinoma tumours/animals were used in this IACUC-approved study. Initially, 60 tumours (n=6, each subgroup) were randomised into five groups: (1) RF alone, (2) intravenous (IV) liposomal quercetin alone (1 mg/kg), (3) IV liposomal quercetin followed 24 h later with RF, (4) RF followed 15 min later by IV liposomal doxorubicin (8 mg/kg), (5) IV liposomal quercetin 24 h before RF followed by IV liposomal doxorubicin 15 min post-ablation. Animals were sacrificed 4 or 24 h post-treatment and gross coagulation diameters were compared. Next, immunohistochemistry staining was performed for Hsp70 and cleaved caspase-3 expression. Comparisons were performed by using Student t-tests or ANOVA.

RESULTS

Combination RF-quercetin significantly increased coagulation size compared with either RF or liposomal quercetin alone (13.1±0.7 mm vs. 8.8±1.2 mm or 2.3±1.3 mm, respectively, P<0.001 for all comparisons). Triple therapy (quercetin-RF-doxorubicin) showed larger coagulation diameter (14.5±1.0 mm) at 24 h than quercetin-RF (P=0.016) or RF-doxorubicin (13.2±1.3 mm, P=0.042). Combination quercetin-RF decreased Hsp70 expression compared with RF alone at both 4 h (percentage of stained cells/hpf 22.4±13.9% vs. 38.8±16.1%, P<0.03) and 24 h (45.2±10.5% vs. 81.1±3.6%, P<0.001). Quercetin-RF increased cleaved caspase-3 expression at both 4 h (percentage of stained cells/hpf 50.7±13.4% vs. 41.9±15.1%, P<0.03) and 24 h (37.4±7.8% vs. 33.2±6.5%, P=0.045); with, triple therapy (quercetin-RF-doxorubicin) resulting in the highest levels of apoptosis (45.1±10.7%) at 24 h. Similar trends were observed for rim thickness.

CONCLUSIONS

Suppression of HSP production using adjuvant liposomal quercetin can increase apoptosis and improve RF ablation-induced tumour destruction. Further increases in tumour coagulation can be seen including an additional anti-tumour adjuvant agent such as liposomal doxorubicin.

Radiofrequency ablation combined with percutaneous ethanol injection in patients with hepatocellular carcinoma

BACKGROUND AND STUDY AIMS

Hepatocellular carcinoma (HCC) is a major burden on health-care systems worldwide. Although radiofrequency ablation (RFA) is currently considered the best technique for coagulative necrosis, the superiority of concomitant use of RFA and percutaneous ethanol injection (PEI) needs to be determined. The study was designed to compare efficacy, safety and rate of survival of patients with HCC assigned to receive combined PEI-RFA versus RFA alone and versus PEI alone.

PATIENTS AND METHODS

This 3-year study enrolled 90 cirrhotic patients with HCC (Child's class A or B, but not class C). They were randomly assigned for either PEI-RFA (group I), RFA alone (group II) or PEI alone (group III). The primary end point was ablation of the tumour. The secondary end point was rate of survival and recurrence.

RESULTS

After the first session, complete ablation was significantly higher in the combination group (87.9%) compared with the RFA group (54.54%). After the second session, complete ablation was achieved in 97.0% of the combination group and in 84.8% of the RFA group. Regarding the PEI group, 75% had complete ablation, whereas 25% had partial ablation after multiple sessions. The survival rate, 1.5 years later, was significantly higher in group I (86.7%) compared with group III (63.3%). The overall incidence of serious adverse events was nil.

CONCLUSION

Combined treatment is superior to RFA alone and to PEI alone, in safety and efficacy in patients with HCC.

The minimal ablative margin of radiofrequency ablation of hepatocellular carcinoma (> 2 and < 5 cm) needed to prevent local tumor progression: 3D quantitative assessment using CT image fusion

OBJECTIVE

The aim of this study was to elucidate the minimal ablative margin for percutaneous radiofrequency ablation (RFA) of hepatocellular carcinoma (HCC) (> 2 and < 5 cm) needed to prevent local tumor progression using CT image fusion and a 3D quantitative method.

MATERIALS AND METHODS

From April 2005 to March 2007, we performed percutaneous RFA for the treatment of 382 HCCs larger than 2 cm and smaller than 5 cm. A total of 110 tumors in 103 patients (77 men and 26 women; mean age, 59.7 years) that were previously untreated and were monitored for at least 1 year were retrospectively enrolled. A 5-mm safety margin was attempted in all cases, and a CT finding of complete replacement of the index tumor by RFA zone was defined as technical success. We constructed fusion images of CT images obtained before and after RFA and performed radial multiplanar reformation with the rotation axis at the center of the tumor to analyze the ablative margin quantitatively. Risk factors for local tumor progression (the thinnest ablative margin, tumor size, and the effect of hepatic vessels) were assessed by multivariate analysis.

RESULTS

Patients underwent follow-up for 12.9-46.6 months (median, 28.1 months). The tumors were 2.1-4.8 cm (mean +/- SD, 2.7 +/- 0.6 cm) in diameter. The thinnest ablative margins ranged from 0 to 6 mm (1.0 +/- 1.4 mm). A 5-mm safety margin was achieved in only 2.7% (3/110) of cases. In 47.3% (52/110) of cases, vessel-induced indentation of the ablation zone contributed to the thinnest ablative margins. Local tumor progression was detected in 27.3% (30/110) of cases. Concordance between local tumor progression and the thinnest margin was observed in 83.3% (25/30) of cases. The incidence of concordant local tumor progression was 22.7% (25/110), 18.9% (10/53), 5.9% (2/34), and 0% (0/15) in tumors with the thinnest ablative margin of > or = 0, > or = 1, > or = 2, and > or = 3 mm, respectively. An insufficient ablative margin was the sole significant factor associated with local tumor progression.

CONCLUSION

When the thickness of the ablative margin is evaluated by CT image fusion, a margin of 3 mm or more appears to be associated with a lower rate of local tumor progression after percutaneous RFA of HCC.

Do liposomal apoptotic enhancers increase tumor coagulation and end-point survival in percutaneous radiofrequency ablation of tumors in a rat tumor model?

PURPOSE

To characterize effects of combining radiofrequency (RF) ablation with proapoptotic intravenous liposome-encapsulated paclitaxel and doxorubicin on tumor destruction, apoptosis and heat-shock protein (HSP) production, intratumoral drug accumulation, and end-point survival.

MATERIALS AND METHODS

R3230 mammary adenocarcinomas (n = 177) were implanted in 174 rats in this animal care committee-approved study. Tumors received (a) no treatment, (b) RF ablation, (c) paclitaxel, (d) RF ablation followed by paclitaxel (RF ablation-paclitaxel), (e) paclitaxel before RF ablation (paclitaxel-RF ablation), (f) RF ablation followed by doxorubicin (RF ablation-doxorubicin), (g) paclitaxel followed by doxorubicin without RF ablation (paclitaxel-doxorubicin), or (h) paclitaxel before RF ablation, followed by doxorubicin (paclitaxel-RF ablation-doxorubicin). Tumor coagulation area and diameter were compared at 24-96 hours after treatment. Intratumoral paclitaxel uptake with and without RF ablation were compared. Immunohistochemical staining revealed cleaved caspase-3 and 70-kDa HSP (HSP70) expression. Tumors were randomized into eight treatment arms for Kaplan-Meier analysis of defined survival end-point (3.0-cm diameter).

RESULTS

Paclitaxel-RF ablation increased tumor coagulation over RF ablation or paclitaxel (mean, 14.0 mm ± 0.9 [standard deviation], 6.7 mm ± 0.6, 2.5 mm ± 0.6, respectively; P < .001). Paclitaxel-RF ablation-doxorubicin had similar tumor coagulation (P < .05), compared with paclitaxel-RF ablation, at 24 and 96 hours. Mean intratumoral paclitaxel accumulation for paclitaxel-RF ablation (6.76 μg/g ± 0.35) and RF ablation-paclitaxel (9.28 μg/g ± 0.87) increased over that for paclitaxel (0.63 μg/g ± 0.25, P < .001). Paclitaxel substantially increased apoptosis and decreased HSP70 expression at coagulation margin. Mean end-point survival for paclitaxel-RF ablation-doxorubicin (56.8 days ± 25.3) was greater, compared with that for paclitaxel-RF ablation or RF ablation-paclitaxel (17.6 days ± 2.5), RF ablation-doxorubicin (30.3 days ± 4.9, P < .002), or paclitaxel-doxorubicin (27.9 days ± 4.1, P < .001).

CONCLUSION

Selecting adjuvant liposomal chemotherapies (paclitaxel, doxorubicin) to target cellular apoptosis and HSP production effectively increases RF ablation-induced tumor coagulation and end-point survival, and combined multidrug approach results in even better outcomes.

SUPPLEMENTAL MATERIAL

http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.10100500/-/DC1.

Combination radiofrequency ablation and intravenous radiolabeled liposomal Doxorubicin: imaging and quantification of increased drug delivery to tumors

PURPOSE

To identify, with noninvasive imaging, the zone of radiopharmaceutical uptake after combination therapy with radiofrequency (RF) ablation and intravenous administration of technetium 99m ((99m)Tc) liposomal doxorubicin in a small-animal tumor model, and to quantify and correlate the uptake by using imaging and tissue counting of intratumoral doxorubicin accumulation.

MATERIALS AND METHODS

This study was approved by the animal care committee. Two phases of animal experiments were performed. In the first experiment, a single human head-and-neck squamous cell carcinoma tumor was grown in each of 10 male nude rats. Seven of these animals were treated with intravenous (99m)Tc-liposomal doxorubicin followed by RF tumor ablation at a mean temperature of 70 degrees C + or - 2 for 5 minutes, and three were treated with intravenous (99m)Tc-liposomal doxorubicin only. Combination single photon emission computed tomography-computed tomography (SPECT/CT) was performed at 15 minutes, 4 hours, and 20 hours after therapy. In the second experiment, two tumors each were grown in 11 rats, but only one of the tumors was ablated after intravenous administration of (99m)Tc-liposomal doxorubicin. SPECT/CT and planar scintigraphy were performed at the same posttreatment intervals applied in the first experiment, with additional planar imaging performed at 44 hours. After imaging, tissue counting in the excised tumors was performed. Radiotracer uptake, as determined with imaging and tissue counting, was quantified and compared. In a subset of three animals, intratumoral doxorubicin accumulation was determined with fluorimetry and correlated with the imaging and tissue-counting data.

RESULTS

At both SPECT/CT and planar scintigraphy, increased uptake of (99m)Tc-liposomal doxorubicin was visibly apparent in the ablated tumors. Results of quantitative analysis with both imaging and tissue counting confirmed significantly greater uptake in the RF ablation-treated tumors (P < .001). Intratumoral doxorubicin accumulation correlated closely with imaging (r = 0.9185-0.9871) and tissue-counting (r = 0.995) results.

CONCLUSION

Study results show that increased delivery of intravenous liposomal doxorubicin to tumors combined with RF ablation can be depicted and quantified with noninvasive imaging.

Percutaneous microwave ablation of liver cancer adjacent to the gastrointestinal tract

PURPOSE

The purpose of the study was to prospectively evaluate safety and effectiveness of percutaneous microwave ablation under temperature monitoring assisted with ethanol injection for liver cancer abutting gastrointestinal tract.

MATERIALS AND METHODS

One hundred seventy-nine hepatic tumors that underwent percutaneous microwave ablation with curative intention were included. Fifty-three lesions located less than 5 mm from gastrointestinal tract were in gastrointestinal group. One hundred twenty-six lesions located more than 5 mm from hepatic surface and first or second branch of hepatic vessels were in control group. The temperature of marginal ablation tissue proximal to gastrointestinal tract was monitored and controlled to fluctuating between 45 degrees C and 58 degrees C for more than 10 min for tumors in the gastrointestinal group. Ethanol (2-27 ml) was injected into marginal tissue in 33 of 53 lesions of the GI group.

RESULTS

Forty-seven of 53 tumors (88.7%) in the gastrointestinal group and 116 of 126 tumors (92.1%) in the control group achieved complete ablation (p > 0.05). There were neither immediate nor periprocedural complications in both groups. Tumor seeding happened in one of the gastrointestinal group and two of the control group. There was no delayed complication of bile ducts injury.

CONCLUSION

Under strict temperature monitoring, microwave ablation assisted with ethanol injection is safe and achieves a high complete ablation rate for hepatic tumors adjacent to gastrointestinal tract.

RF ablation with adjuvant therapy: comparison of external beam radiation and liposomal doxorubicin on ablation efficacy in an animal tumor model

PURPOSE

To determine the critical thermal dosimetry and relative efficacy for RF ablation combined with external beam radiation (XRT) or liposomal doxorubicin (LD), in an animal tumor model.

MATERIALS AND METHODS

This study was performed in two phases, in 13-18 mm diameter R3230 tumors subcutaneously implanted into Fischer rats. In phase 1, tumors (n = 30) were randomized into six groups. RF energy (titrated to 70 degrees C tip temperature) was applied for either 2.5 or 5 min (n = 15, each group). For each duration, one of three adjuvant therapies was applied (n = 5, each): no therapy (control), LD (1 mg intravenously, 30 min post-RF), or XRT (20 Gy at 1 Gy min(-1), within 2 h post-RF), with sacrifice at 48 h for pathologic analysis. In phase 2, thermal mapping was performed in 20 tumors throughout RF application (70 degrees C; 5 min), at 1.5-7 mm distances from the active electrode tip. Temperature profiles throughout the tumor were constructed and were used to interpolate temperatures over time at the critical ablation margin, to derive maximum threshold temperature, AUC (area under the curve) and CEM(43) (cumulative equivalent minutes at 43 degrees C). Ablation sizes and all calculated values were compared within and across experimental groups using MANOVA statistics with pair-wise T-test for individual comparisons.

RESULTS

RF/XRT produced the largest coagulation (11.7 +/- 1.5 mm at 2.5 min, >or=15 +/- 0.7 mm at 5 min), followed by RF/LD, and then RF alone (p < 0.001 for all comparisons). RF/XRT demonstrated temperature threshold decreases from RF alone of 11.7 +/- 0.01 degrees C and 12.7 +/- 0.38 degrees C at 2.5 and 5 min respectively (with absolute thresholds of 42 degrees C for XRT compared to 52 degrees C for RF alone). RF/LD had decreases of 4.0 degrees C at 2.5 min and 4.4 degrees C at 5 min. Thermal dose requirements (AUC) decreased by 7.79% or 9.28% for RF/LD compared to >or=19.36% or 25.82% for RF/XRT at 2.5 and 5 min (p < 0.001). CEM(43) values followed similar patterns (p < 0.001), but with a reduction of 10(1) and 10(4) in magnitude for RF/LD and RF/XRT therapies at 5 min, respectively.

CONCLUSIONS

For a standardized RF dose, the combination of high dose XRT and RF increased ablation size compared to RF and liposomal doxorubicin or RF alone. Increased ablation size is more closely associated with decreased temperature threshold necessary to induce coagulation, rather than the total thermal dose.

Risk factors of survival after percutaneous radiofrequency ablation of hepatocellular carcinoma

AIMS

This study aimed to determine the risk factors of survival in patients with hepatocellular carcinoma (HCC) undergoing percutaneous radiofrequency ablation (PRFA).

PATIENTS AND METHODS

Between August 1999 and May 2005, 281 patients (250 males and 31 females) who were 33-80 years old (mean 65.3 years) received PRFA only or PRFA in combination with percutaneous ethanol injection (PEI) in our center. Patients were treated with PRFA or PEI by a percutaneous approach with ultrasound (US) guidance and were evaluated at regular intervals to determine disease recurrence and survival. The survival curves were constructed by the Kaplan-Meier method and compared by the log-rank test. The relative significance of the variables in the risk factors of overall survival was assessed by multivariate Cox proportional hazards regression analysis.

RESULTS

At the end of the study, 189 patients were alive, and 92 were dead. Median survival was 48.7 months. The overall 1-, 3-, and 5-year survival rates were 89%, 54%, and 43%, respectively. The overall 1-, 3-, and 5-year survival rates for small tumor (size < or = 3cm) were 97.8%, 65.7%, 58.6%, respectively, for medium tumor (size 3.1-5cm) 94.1%, 57.1%, 37.1%, respectively, and for large tumor (size >5cm) 62.8%, 40.3%, 0%, respectively. Survival of patients treated with PRFA was dependent on tumor size (p<0.001; risk ratio [RR] 9.6, 95% CI 5.2-17.8), number of tumors (p=0.003; RR 1.6, 95% CI 1.2-2.0), combination with PEI (p=0.01; RR 0.6, 95% CI 0.4-0.9), Child-Pugh class (p=0.002; RR 2.0, 95% CI 1.3-3.0) and safety margin (p=0.0026; RR 0.6, 95% CI 0.4-0.9).

CONCLUSIONS

PRFA is an effective treatment for HCC. This study showed after PRFA, tumor size, number of tumors, combination with PEI, safety margin, and Child-Pugh class were independent risk factors of survival.

Combined Percutaneous Radiofrequency Ablation and Ethanol Injection of Renal Tumours: Midterm Results

OBJECTIVES

To evaluate the safety and efficacy of combined percutaneous, image-guided, radiofrequency (RF) ablation and ethanol injection of renal tumours, and to present our midterm results.

METHODS

Since February 2002, 27 consecutive patients (22 men, 5 women; age range: 39-84 yr; mean: 69) with 28 renal tumours (mean diameter: 2.87cm) were treated with combined percutaneous RF and ethanol ablation, and were prospectively evaluated. Twenty-five patients were considered nonsurgical candidates because of comorbid conditions (16 patients) or had previous nephrectomy (9 patients), and 2 had refused surgery. Thirty-three ablation sessions were performed, with computed tomography (26 sessions), ultrasound (6), or combined magnetic resonance imaging/fluoroscopic guidance in 1. Absolute ethanol (0.5-3ml; mean: 1.7) was injected into the tumour immediately before treatment with radiofrequency. Mean follow-up period was 18.6 mo (range: 3-56).

RESULTS

Twenty-seven of the 28 tumours were completely ablated with either one (21 tumours) or two treatment sessions (6 tumours). One patient with residual disease refused further treatment. Only three minor complications, including a subcapsular haematoma and two patients with loin pain, occurred; all three patients were treated conservatively. None of the complications was related to the ethanol injection. During the follow-up period, no evidence of local recurrence or metastatic disease was seen. Creatinine levels have not changed significantly in any of the patients following ablation.

CONCLUSIONS

Combined use of percutaneous RF and ethanol ablation is a safe and effective alternative treatment for selective patients with renal tumours.

"Wide local ablation" of localized breast cancer using high intensity focused ultrasound

BACKGROUND AND OBJECTIVE

High intensity focused ultrasound (HIFU) is a non-invasive technique for tumor ablation. The goal of this study was to investigate the feasibility of performing wide local ablation using ultrasound-guided HIFU in the treatment of patients with localized breast cancer.

METHODS

Twenty-three patients with histologically proven breast cancer were enrolled in this prospective clinical trial. They underwent HIFU treatment for breast cancer including the tumor and 1.5-2.0 cm normal breast tissue surrounding the tumor, followed by modified mastectomy 1-2 weeks after HIFU. Radiological examination, histological, and terminal deoxynucleotidyl transferase-mediated nick end labeling (TUNEL) methods were performed to evaluate therapeutic effects in the treated region.

RESULTS

Thermal ablation was confirmed in all 23 patients. It included tumor and normal breast tissue surrounding the tumor. Mean values of the largest parallel and perpendicular dimensions, and volume of HIFU lesions in excised breasts were significantly larger than those of the targeted tumors respectively (P < 0.001). Hematoxylin and eosin (H & E) staining showed clear evidence of complete coagulation necrosis in the treated regions. However, no apoptotic cells were detected in either treated tumor or normal breast tissue.

CONCLUSION

As a non-invasive therapy, ultrasound-guided HIFU can induce wide local ablation in the treatment of patients with localized breast cancer.

Hepatocellular Carcinoma Treated with Radiofrequency Ablation with or without Ethanol Injection: A Prospective Randomized Trial

PURPOSE

To prospectively evaluate whether use of combined radiofrequency ablation (RFA) and percutaneous ethanol injection (PEI) results in better survival compared with use of RFA alone in patients with hepatocellular carcinoma.

MATERIALS AND METHODS

This study was local ethical committee approved; all patients gave written informed consent. One hundred thirty-three patients were randomly assigned to undergo RFA-PEI (n = 66; 57 men, nine women; mean age, 53.3 years; age range, 32-73 years) or RFA alone (n = 67; 58 men, nine women; mean age, 52.2 years; age range, 33-74 years). Patients with viable tumors at computed tomography (CT) 4 weeks after treatment received additional treatment. Overall survival rates were calculated and 3-year survival rates were compared with life-table and Mantel-Haenszel analyses, respectively. Survival curves were constructed and compared by using Kaplan-Meier and log-rank tests, respectively. The relative prognostic significance of variables in predicting overall survival and the time to tumor recurrence or metastasis were assessed with multivariate Cox proportional hazards regression and logistic regression analyses, respectively.

RESULTS

One-, 2-, 3-, 4-, and 5-year overall survival rates were 95.4%, 89.2%, 75.8%, 63.3%, and 49.3%, respectively, with RFA-PEI and 89.6%, 68.7%, 58.4%, 50.3%, and 35.9%, respectively, with RFA alone. The survival curve for the RFA-PEI group was significantly better than that for the RFA-only group (P = .04). The survival curve for the RFA-PEI group was better than that for the RFA-only group with 3.1-5.0-cm tumors (P = .03) but not for those with 3.0 cm or smaller (P = .44) or 5.1-7.0-cm (P = .70) tumors. Overall tumor recurrence was lower with RFA-PEI (23 patients) than with RFA alone (33 patients, nonsignificant difference). Local recurrence was significantly lower with RFA-PEI (four patients) than with RFA alone (14 patients, P = .012). Tumor diameter proved to be the only significant prognostic factor for overall recurrence and intrahepatic recurrence. Treatment type and tumor size were significant prognostic factors for local recurrence.

CONCLUSION

RFA-PEI facilitated better local tumor control and long-term survival compared with RFA alone.

Investigation of the influence of blood flow rate on large vessel cooling in hepatic radiofrequency ablation

Radiofrequency (RF) ablation using high-frequency current has become an important treatment method for patients with non-resectable liver tumors. Tumor recurrence is associated with tissue cooling in the proximity of large blood vessels. This study investigated the influence of blood flow rate on tissue temperature and lesion size during monopolar RF ablation at a distance of 10 mm from single 4- and 6-mm vessels using two different approaches: 1) an ex vivo blood perfusion circuit including an artificial vessel inserted into porcine liver tissue was developed; and 2) a finite element method (FEM) model was created using a novel simplified modeling technique for large blood vessels. Blood temperatures at the inflow/outflow of the vessel and tissue temperatures at 10 and 20 mm from the electrode tip were measured in the ex vivo set-up. Tissue temperature, blood temperature and lesion size were analyzed under physiological, increased and reduced blood-flow conditions. The results show that changes in blood flow rate in large vessels do not significantly affect tissue temperature and lesion size far away from the vessel. Monopolar ablation could not produce lesions surrounding the vessel due to the strong heat-sink effect. Simulated tissue temperatures correlated well with ex vivo measurements, supporting the FEM model.

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.

Combined Radiofrequency Ablation and Adjuvant Liposomal Chemotherapy: Effect of Chemotherapeutic Agent, Nanoparticle Size, and Circulation Time

PURPOSE

To evaluate the effects of liposomal chemotherapeutic agent, nanoparticle size, and liposome circulation time on tissue coagulation and intratumoral drug uptake when radiofrequency (RF) ablation is combined with adjuvant intravenous liposomal chemotherapy in an animal breast tumor model.

MATERIALS AND METHODS

Ninety-one R3230 mammary adenocarcinoma nodules were implanted in 48 Fischer rats. First, standardized RF ablation was combined with intravenous liposomal doxorubicin, cisplatin, or 5-fluorouracil (35 tumors each). Second, three different-sized doxorubicin-containing nanoparticle preparations were combined with standardized RF ablation. Last, two doxorubicin-containing liposome preparations with different blood elimination half-lives were combined with RF ablation. Coagulation diameter and interstitial doxorubicin concentration were measured 48 hours after treatment and compared with use of statistical analysis.

RESULTS

All combinations of RF with liposomal chemotherapy caused significantly greater tumor necrosis than RF alone (P<.05). Significantly increased necrosis was observed with intravenous liposomal RF/doxorubicin and RF/cisplatin compared with intravenous liposomal RF/5-fluorouracil (P<.01). Greater coagulation was observed with RF combined with 100-nm nanoparticles compared with 20-nm or 250-nm nanoparticles (P=.01 and P=.04, respectively). Additionally, greater intratumoral doxorubicin uptake was observed in the group treated with 20-nm nanoparticles compared with those treated with other sizes of nanoparticles (P<.05). RF plus liposomal doxorubicin produced greater coagulation and intratumoral doxorubicin uptake than RF plus 1,2-dipalmitoyl-sn-glycero-3-phosphatidic acid (P<.05).

CONCLUSION

When combined with RF ablation, modification of adjuvant intravenous liposomal chemotherapy, including nanoparticle size, circulation time, and chemotherapeutic agent, can influence intratumoral drug accumulation and tissue coagulation.

Radiofrequency Thermal Ablation: Increase in Lesion Diameter with Continuous Acetic Acid Infusion

PURPOSE

To evaluate the influence of continuous infusion of acetic acid 50% during radiofrequency ablation (RFA) on the size of the thermal lesion produced.

METHODS

Radiofrequency (RF) was applied to excised bovine liver by using an expandable needle electrode with 10 retractable tines (LeVeen Needle Electrode, RadioTherapeutics, Sunnyvale, CA) connected to a commercially available RF generator (RF 2000, RadioTherapeutics, Sunnyvale, CA). Experiments were performed using three different treatment modalities: RF only (n = 15), RF with continuous saline 0.9% infusion (n = 15), and RF with continuous acetic acid 50% infusion (n = 15). RF duration, power output, tissue impedance, and time to a rapid rise in impedance were recorded. The ablated lesions were evaluated both macroscopically and histologically.

RESULTS

The ablated lesions appeared as spherical or ellipsoid, well-demarcated pale areas with a surrounding brown rim with both RF only and RF plus saline 0.9% infusion. In contrast, thermolesions generated with RF in combination with acetic acid 50% infusion were irregular in shape and the central portion was jelly-like. Mean diameter of the coagulation necrosis was 22.3 +/- 2.1 mm (RF only), 29.2 +/- 4.8 mm (RF + saline 0.9%) and 30.7 +/- 5.7 mm (RF + acetic acid 50%), with a significant increase in the RF plus saline 0.9% and RF plus acetic acid 50% groups compared with RF alone. Time to a rapid rise in impedance was significantly prolonged in the RF plus saline 0.9% and RF plus acetic acid 50% groups compared with RF alone.

CONCLUSIONS

A combination of RF plus acetic acid 50% infusion is able to generate larger thermolesions than RF only or RF combined with saline 0.9% infusion.

Combination radiofrequency ablation with intratumoral liposomal doxorubicin: effect on drug accumulation and coagulation in multiple tissues and tumor types in animals

PURPOSE

To determine whether use of radiofrequency (RF) ablation combined with intravenously (IV) administered liposomal doxorubicin, as compared with use of RF ablation or doxorubicin alone, facilitates increased tissue coagulation and interstitial drug accumulation in animal models.

MATERIALS AND METHODS

The institutional animal care and use committee approved this study. In experiment 1, multiple canine sarcomas were implanted in seven mildly immunosuppressed dogs and grown to a mean diameter of 4.8 cm. Tumors were assigned to three treatment groups: internally cooled RF ablation (12 minutes, 2000-mA pulsed technique) followed by IV liposomal doxorubicin (10 mg per animal) (n = 6), RF ablation alone (n = 6), and liposomal doxorubicin alone (n = 4). In experiment 2, the livers and kidneys of 10 rabbits and the thigh muscles of 10 rats were randomly assigned to one of two treatment groups: conventional RF ablation (90 degrees C +/- 2, 5 minutes) followed by IV liposomal doxorubicin (5 mg per rabbit, 1 mg per rat) or RF ablation alone (n = 5, each). Coagulation diameter and interstitial doxorubicin concentration (tissues were homogenized in acid alcohol, with doxorubicin extracted for 24 hours at 5 degrees C and quantified with fluorimetry) were measured 48 hours after treatment and compared. Multivariate analysis of variance and subsequent pairwise t tests (alpha = .05, two-tailed test) were performed.

RESULTS

Data are means +/- standard errors of the mean. A larger diameter of tumor destruction was observed in canine sarcomas treated with RF ablation-liposomal doxorubicin (3.7 cm +/- 0.6) compared with that in tumors treated with RF ablation (2.3 cm +/- 0.1) or liposomal doxorubicin (0.0 cm +/- 0.0) alone (P < .01). A new finding was a completely necrotic red zone (1.6 cm +/- 0.7) surrounding the central RF ablation-induced white coagulation zone. Greater but nonuniform drug uptake was observed particularly in this red zone (77.0 ng/g +/- 18.2) compared with uptake in the central zone (15.1 ng/g +/- 3.2), peripheral area of untreated tumor (38.9 ng/g +/- 8.0), and tumors treated with liposomal doxorubicin alone (43.9 ng/g +/- 6.7 for all regions) (P < .01 for all individual comparisons). In experiment 2, use of combined therapy led to increased coagulation in all tissues (liver: 17.6 mm +/- 3.1, P = .03; kidney: 11.0 mm +/- 3.1, P = .03; muscle: 13.1 mm +/- 1.3, P < .01) compared with use of RF ablation alone (liver, 13.4 mm +/- 1.5; kidney, 7.9 mm +/- 0.7; muscle, 8.6 mm +/- 0.5). Combined therapy, as compared with liposomal doxorubicin therapy alone, was also associated with increased doxorubicin accumulation in liver, kidney, and muscle (1.56 microg/g +/- 0.34, 4.36 microg/g +/- 1.78, and 3.63 microg/g +/- 1.43, respectively, vs 1.00 microg/g +/- 0.18, 1.23 microg/g +/- 0.32, and 0.87 microg/g +/- 0.53, respectively) (P < or = .01 for all individual comparisons).

CONCLUSION

Use of RF ablation combined with liposomal doxorubicin facilitates increased tissue coagulation and interstitial doxorubicin accumulation in multiple tissues and tumor types and may be useful for treatment of large tumors and achieving an ablative margin within the untreated tissue surrounding RF ablation-treated tumors.

Survival and intra-hepatic recurrences after laparoscopic radiofrequency of hepatocellular carcinoma in patients with liver cirrhosis

BACKGROUND

The optimal treatment for hepatocellular carcinoma (HCC) is surgical resection. However, only a small percentage of patients are operative candidates. Percutaneous radiofrequency interstitial thermal ablation proved to be effective, too. Our objective was to assess a novel operative combination of laparoscopic ultrasound (LUS) with laparoscopic radiofrequency (LRF) in the treatment of HCC not amenable to liver resection.

METHODS

One hundred and four patients with HCC in liver cirrhosis were submitted to laparoscopic LRF. A LRF was indicated in patients not amenable to liver resection that had at least one of the following criteria: (a) severe impairment of the coagulation tests; (b) large tumors (but <5 cm) or multiple lesions requiring repeated punctures; (c) superficial lesions adjacent to visceral structures; (d) deep-sited lesions with a very difficult or impossible percutaneous approach; (e) short-term recurrence of HCC following percutaneous loco-regional therapies.

RESULTS

The LRF procedure was completed in 102 out of 104 patients (98% feasibility rate). LUS identified 26 new malignant lesions (25%) undetected by pre-operative imaging. There was no operative mortality. Seventy-six patients had no complication (73%). At 1-month computed tomography (CT) evaluation, a complete response with a 100% necrosis was achieved in 88 out of 101 patients (87%). During the follow-up (mean follow-up: 22.5 +/- 15.9 months), 55 patients (54%) developed new malignant nodules (42% of these recurrences were localized in the same segment of the HCC treated).

CONCLUSIONS

LRF of HCC proved to be a safe and effective technique at least in the short and mid-term: in fact it permits to treat lesions not treatable with the per cutaneous approach, to detect 25% of new HCC nodules and it has a low morbidity rate.

Combined radiofrequency and alcohol injection for percutaneous hepatic tumor ablation

OBJECTIVE

We sought to determine if alcohol potentiates radiofrequency energy by obtaining larger ablative volumes in 30 liver tumors in human patients.

SUBJECTS AND METHODS

We compared two groups of patients: one group treated with radiofrequency ablation alone (radiofrequency-alone group), and a second group treated with radiofrequency ablation and immediate prior injection of alcohol (combined group). The radiofrequency-alone group comprised 20 ablations (mean diameter, 8.4 cm; colorectal cancer metastases [n = 15]; other metastases [n = 5]). The combined group consisted of 30 radiofrequency ablations (mean diameter, 8.8 cm; metastatic colorectal cancer [n = 17]; other metastases [n = 8]; and hepatocellular carcinoma [n = 5]) treated with alcohol injection immediately before radiofrequency ablation. The amount of alcohol injected was determined by the size and location of tumors. Preprocedural laboratory tests (complete blood cell count with differential, liver function tests, and coagulation parameters) were performed in all patients, along with pre- and postprocedural CT, MRI, and PET. Measurements of tissue necrosis were obtained on the postprocedural CT scans and MR images. Volumes of necrosis calculated in each group were corrected for the number of radiofrequency applications and were statistically compared using the Student's t test. In addition, tissue impedances obtained during the radiofrequency ablation procedure were compared between the two groups.

RESULTS

The mean ablation volumes for the radiofrequency-alone group were 32.3 cm(2) (median, 28.6 cm(2); range, 14.4-61.8 cm(2)) and for the combined group, 84.6 cm(2) (median, 78.3 cm(2); range, 34.6-149 cm(2)). The difference in the necrosis volumes was significantly larger (p < 0.0001) in the combined group. Overall, the combined treatment group underwent fewer radiofrequency applications per session. Tissue impedance during radiofrequency ablation was higher in the combined group (mean, 62.7 vs 57.3 Omega in the radiofrequency alone group; p = 0.0005) at comparable times during the ablations. No major complications were seen in either group.

CONCLUSION

Percutaneous radiofrequency ablation appears to be potentiated by immediate prior alcohol injection into the tumor. Consistently larger lesions are obtainable in fewer sessions, without any increase of complications, using the combined method.

Hepatic bipolar radiofrequency ablation using perfused-cooled electrodes: a comparative study in theex vivobovine liver

The purpose of this paper was to demonstrate the efficacy of the dual probe bipolar radiofrequency (RF) system with the perfused-cooled electrodes inducing coagulation necrosis in the ex vivo bovine liver. The perfused-cooled electrode that allows simultaneous internal cooling and interstitial hypertonic saline perfusion has been developed for RF ablation (RFA). RF was applied to excised bovine liver in a bipolar mode at 150 W using a 200 W generator with two perfused-cooled electrodes for 10 min. After placing the electrodes at 3 cm spacing in the explanted liver, 45 ablation zones were created with three different regimens: Group A, using both intraelectrode cooling and interstitial perfusion; group B, using only the intraelectrode cooling; and group C, using only interstitial perfusion. In groups A and C, RFA was performed with the infusion of 6% hypertonic saline at the rate of 2 ml min(-1). During RFA, we measured the tissue temperature at the midpoint between the two electrodes. The dimensions of the ablation zones and the changes in impedance, currents and liver temperature during RFA were compared in these three groups. The mean tissue impedance during RFA in group A (56.7+/-21.7 Omega) and group C (56.9+/-20.6 Omega) was significantly lower than group B (112+/-19.7 Omega) (p<0.001). The mean current was higher in group A (1765+/-128 mA) than groups B (760+/-321 mA) and C (1298+/-349 mA) (p<0.05). In addition, the shortest vertical diameter of coagulation necrosis was greater in groups A (4.9+/-0.5 cm) and C (4.6+/-0.7 cm) than in group B (3.5+/-0.4 cm) (p<0.05). The temperature at the mid-point between the two probes was higher in group A than other groups: 99 degrees C in group A, 88.9 degrees C in group B, and 94.3 degrees C in group C (p>0.05). The ratios of the diameter of the long-axis to the diameter of the vertical-axis of groups A, B and C were 1.1+/-0.1, 1.2+/-0.1, and 1.1+/-0.2, respectively (p<0.05). Bipolar RFA using intraelectrode cooling and the interstitial saline perfusion simultaneously produced ablation zones significantly larger than the area produced by only one measure.

Bipolar radiofrequency ablation in ex vivo bovine liver with the open-perfused system versus the cooled-wet system

The aim of this study was to investigate the efficacy of bipolar radiofrequency ablation (RFA) with the open-perfused electrode and cooled-wet electrode. Bipolar RF was applied for 20 min to the ex vivo bovine liver using either the Berchtold system with two 16-gauge open-perfused electrodes (group A, n=15) or the Radionics system with two 15-gauge cooled-wet electrodes (group B, n=15). In both groups, two electrodes were placed 3 cm apart. The ablation zone was created by the RF energy delivered together with the infusion of 5% hypertonic saline (2 ml/min). The dimension of the ablation zone, its shape and the changes in the impedance and W s of two groups during the RFA were examined and documented. The vertical diameter (Dv) along the probe, the long-axis diameter (Dl) perpendicular to the Dv in the longitudinal plane and the short-axis diameter of the ablation zone (Ds) in the transverse plane through the midpoint between the tips of two probes were measured. The mean accumulated energy output in the Radionics system was higher than in the Berchtold system (159,887.0+/-36,423 W s vs. 87,555.1+/-86,787 W s). The difference was statistically significant (P<0.05). In group A, the impedance intermittently rose to above 700 Omega during the RFA in all sessions, which led to a gradual decrease of the power output to lower than 30 W. In group B, on the other hand, the impedance did not change markedly. The mean Dv value of the coagulation necrosis in group B was significantly longer than in group A (5.0+/-0.4 cm vs. 4.3+/-0.6 cm, P<0.05). The mean Dl and Ds were 6.7+/-0.5 cm and 5.0+/-0.8 cm in group A, and 6.5+/-0.8 cm and 5.5+/-0.7 cm in group B, respectively (P>0.05). The data demonstrate that the cooled-wet electrode generates the more spherical ablation zone than the open-perfused electrode. With approximately doubled power output, the bipolar RFA with the cooled-wet electrodes induces a larger volume of tissue coagulation than with the open-perfused electrodes.

Combined radiofrequency ablation and acetic acid hypertonic saline solution instillation: an in vivo study of rabbit liver

Objective

We wanted to determine whether combined radiofrequency ablation (RFA) and acetic acid-hypertonic saline solution (AHS) instillation can increase the extent of thermally mediated coagulation in in vivo rabbit liver tissue. We also wished to determine the optimal concentration of the solution in order to maximize its effect on extent of the RFA-induced coagulation.

Materials and Methods

Forty thermal ablation zones were produced in 40 rabbits by using a 17-gauge internally cooled electrode with a 1-cm active tip under ultrasound guidance. The rabbits were assigned to one of four groups: group A: RFA alone (n=10); group B: RFA with 50% AHS instillation (n=10); group C: RFA with 25% AHS instillation (n=10); group D: RFA with 15% AHS instillation (n=10). A range of acetic acid concentrations diluted in 36% NaCl to a total volume of 1 mL were instilled into the liver before RFA. The RF energy (30 W) was applied for three minutes. After RFA, in each group, the maximum diameters of the thermal ablation zones in the gross specimens were compared. Technical success and the complications that arose were evaluated by CT and on the basis of autopsy findings.

Results

All procedures are technically successful. There were six procedure-related complications (6/40; 15%): two localized perihepatic hematomas and four chemical peritonitis. The incidence of chemical peritonitis was highest for group B with the 50% AHS solution instillation (30%). With instillation of 15% AHS solution, a marked decrease of tissue impedance (24.5 ± 15.6 Ω) and an increase of current (250 mA) occurred as compared to RFA alone. With instillation of the solutions before RFA (group B, C and D), this produced a greater mean diameter of coagulation necrosis than the diameters for rabbits not instilled with the solution (group A) (p < 0.05). However, there was no significant difference between group B, C, and D.

Conclusion

Combined AHS instillation and RFA can increase the dimension of coagulation necrosis in the liver with a single application. A low concentration of AHS (15%) showed similar effects in increasing the extent of RF-induced coagulation, but there were less side effects as compared to the high concentration of AHS.

Ultrasound-guided percutaneous thermal ablation of hepatocellular carcinoma using microwave and radiofrequency ablation

AIM

To investigate the therapeutic efficacy of thermal ablation for treatment of hepatocellular carcinoma (HCC) using microwave and radiofrequency (RF) energy application.

MATERIALS AND METHODS

A total of 190 nodules in 97 patients (84 male, 13 female; mean age 53.4 years, range 24-74 years) with HCC were treated with microwave or RF ablation in the last 4 years. The applicators were introduced into the tumours under conscious analgesic sedation by intravenous administration of fentanyl citrate and droperidol and local anaesthesia in both thermal ablation procedures. The patients were then followed up with contrast-enhanced computed tomography (CT) to evaluate treatment response. Survival was analysed using the Kaplan-Meier method.

RESULTS

Complete ablation was obtained in 92.6% (176/190) nodules. The complete ablation rates were 94.6% (106/112) in microwave ablation and 89.7% (70/78) in RF ablation. The complete ablation rates in tumours</=2.0, 2.1-3.9 and >/=4.0 cm were 93.1, 93.8 and 86.4%, respectively. Local recurrence was found in 9.5% nodules and the rates in tumours</=2.0, 2.1-3.9 and >/=4.0 cm in diameter were 3.4, 9.9 and 31.8%, respectively. In the follow-up period, 7.1% nodules ablated by microwave and 12.8% by RF presented local recurrence. The 1, 2 and 3-year distant recurrence-free survivals were 47.2, 34.9 and 31.0%, respectively. Estimated mean survival was 32 months, and 1, 2 and 3-year cumulative survivals were 75.6, 58.5, and 50.0%, respectively. One and 2 years survivals of Child-Pugh class A, B and C patients were 83.8 and 70.4%, 78.2 and 53.2%, 36.3 and 27.3%, respectively.

CONCLUSION

Thermal ablation therapy by means of microwave and RF energy application is an effective and safe therapeutic technique for hepatocellular carcinoma. Large tumours can be completely ablated, but have a significantly higher risk of local recurrence at follow-up.

A comparative experimental study of the in-vitro efficiency of hypertonic saline-enhanced hepatic bipolar and monopolar radiofrequency ablation

OBJECTIVE

To compare the in-vitro efficiency of a hypertonic saline (HS)-enhanced bipolar radiofrequency (RF) system with monopolar RF applications by assessing the temperature profile and dimensions of RF-created coagulation necrosis in bovine liver.

MATERIALS AND METHODS

A total of 27 ablations were performed in explanted bovine livers. After placement of two 16-gauge open-perfused electrodes at an interelectrode distance of 3 cm, 5% HS was instilled into tissue at a rate of 1 mL/min through the electrode. Seventeen thermal ablation zones were created in the monopolar mode (groups A, B), and ten more were created using the two open-perfused electrodes in the bipolar mode (group C). RF was applied to each electrode for 5 mins (for a total of 10 mins, group A) or 10 mins (for a total of 20 mins, group B) at 50W in the sequential monopolar mode, or to both electrodes for 10 min in the bipolar mode (group C). During RF instillation, we measured tissue temperature at the midpoint between the two electrodes. The dimensions of the thermal ablation zones and changes in impedance and wattage during RFA were compared between the groups.

RESULTS

With open-perfusion electrodes, the mean accumulated energy output value was lower in the bipolar mode (group C: 26675+/-3047 Watt s) than in the monopolar mode (group A: 28778+/-1300 Watt s) but the difference was not statistically significant (p > 0.05). In the bipolar mode, there were impedance rises of more than 700 ohm during RF energy application, but in the monopolar modes, impedance did not changed markedly. In the bipolar mode, however, the temperature at the mid-point between the two probes was higher (85 degrees C) than in the monopolar modes (65 degrees C, 80 degrees C for group A, B, respectively) (p < 0.05). In addition, in HS-enhanced bipolar RFA (group C), the shortest diameter at the midpoint between the two electrodes was greater than in either of the monopolar modes: 5.4+/-5.6 mm (group A); 28.8+/-8.2 mm (group B); 31.2+/-7.6 mm (group C) (p < 0.05)

CONCLUSION

Using an open perfusion system, HS-enhanced bipolar RFA more efficiently created larger areas of thermal ablation and higher tissue temperatures than monopolar RFA.

Extracorporeal focused ultrasound surgery for treatment of human solid carcinomas: early Chinese clinical experience

The objective of this article is to introduce the early Chinese clinical experience of using extracorporeal focused ultrasound (US) surgery (FUS) for the treatment of solid tumors. From December 1997 to October 2001, a total of 1038 patients with solid tumors underwent FUS ablation in 10 Chinese hospitals. The tumors included primary and metastatic liver cancer, malignant bone tumors, breast cancer, soft tissue sarcomas, kidney cancer, pancreatic cancer, abdominal and pelvic malignant tumors, uterine myoma, benign breast tumors, hepatic hemangioma and other solid tumors. In this article, pathologic changes in tumors treated with FUS, real-time diagnostic imaging for targeting, monitoring and assessment of results by follow-up images are presented. Early clinical results and complications of the technique are also reported.

Combined treatment of radiofrequency ablation and acetic acid injection: an in vivo feasibility study in rabbit liver

The aim of this study was to compare the effects of percutaneous radiofrequency ablation (RFA) combined with percutaneous acetic acid injection (PAI) and either therapy alone for their effects on in vivo rabbit liver tissue. Thirty New Zealand white rabbits were included in this study and were allocated to three groups: group A, conventional RFA (n = 10); group B, PAI (n = 10); and group C, combined RFA and PAI (n = 10). Under US guidance, 1 ml of 50% acetic acid was injected into the target area of the liver parenchyma through a 21-G Chiba needle before performing RFA. The RFA was then performed using a 17-G internally cooled electrode with 1-cm active tip, and RF energy (30 W) was applied for 3 min with or without acetic acid injection. After RFA or PAI, contrast-enhanced CT and CT pathologic correlation were performed. The maximum diameters of the thermal lesions in each group were compared. All procedures were technically successful, and a total of 30 lesions (10 lesions for each group) were produced. The mean maximum diameter of the coagulation necrosis in the rabbits of group C (25+/-9 mm) was significantly larger than the diameters of the other groups: 12.2 +/- 1 mm (group A) and 14.3 +/- 3 mm (group B; p = 0.001). On contrast-enhanced CT scanning, the lesions of group B (7 of 10, 70%) appeared frequently irregular compared with those of groups A (2 of 10, 20%) and C (4 of 10, 40%; p = 0.08). There were seven complications (23.3%): a localized hematoma in a group-A rabbit; two hematomas and one chemical peritonitis in group-B rabbits; and a hematoma, a chemical peritonitis, and a burn injury to the stomach in group-C rabbits. Compared with the group-A rabbits (1 of 10, 10%), the group-B (3 of 10, 30%) and group-C rabbits (3 of 10, 30%) showed a tendency toward complications, but the difference was not significant (p = 0.48). Under the present experimental condition, combined RFA and PAI was able to increase the diameter of coagulation necrosis up to 2.5 cm without significantly increasing complications.