Large-volume tissue ablation with radio frequency by using a clustered, internally cooled electrode technique: laboratory and clinical experience in liver metastases

Technical and Clinical Outcomes of Laparoscopic-Laparotomic Hepatocellular Carcinoma Thermal Ablation with Microwave Technology: Case Series and Review of Literature

PURPOSE

To evaluate technical and clinical outcomes of intraoperative (laparoscopic/laparotomic) microwave ablation on HCC.

MATERIALS AND METHODS

This is a retrospective single-center study evaluating consecutive patients treated for very early/early-stage HCC with intraoperative microwave ablation from 1 July 2017 to 30 June 2023. In these patients, a percutaneous US-guided approach was excluded due to the nodule's suboptimal visibility or harmful location and liver resection for a deep position or adherences. Data about the clinical stage, surgical approach, liver pathology and nodules characteristics, technical success, complications, and follow-up were collected. Technical success was intended as the absence of locoregional persistence at follow-up CT/MRI controls.

RESULTS

A total of 36 cirrhotic patients (M:F = 30:6, median age 67 years) were enrolled; 18/36 (50%) had a single nodule, 13/36 (36%) had two, 4/36 had three (11%), and 1/36 had four (3%). Among the patients, 24 (67%) were treated with laparoscopy, and 12/36 (33%) with a laparotomic approach. Sixty HCCs of 16.5 mm (6-50 mm) were treated for 7 min (2-30 min) with 100 W of power. A total of 55 nodules (92%) were treated successfully and showed no residual enhancement at the first postoperative follow-up; the other 5/60 (8%) underwent chemo/radioembolization. There was one complication (3%): a biliary fistula treated with percutaneous drainage and glue embolization. The average hospital stay was 3.5 days (1-51 days), and patients were followed up on average for 238 days (13-1792 days). During follow-up, 5/36 patients (14%) underwent liver transplantation, 1/36 (2%) died during hospitalization and 1 after discharge.

CONCLUSIONS

Laparoscopic/laparotomic intraoperative HCC MW ablation is feasible in patients unsuitable for percutaneous approach or hepatic resection, with rare complications and with good technical and clinical outcomes.

Interventional oncology of liver tumors: how it all started and where are we now

Liver was the very first organ for which interventional procedures were applied for the local treatment of primary and secondary malignancies. In this paper, the history of Interventional Oncology of liver, from the very beginning to the current situation, is summarized, including both percutaneous and intravascular procedures, and together with the evolution of the techniques for image guidance. The main ongoing developments, such as new techniques, combined interventional treatments and association of local interventions with new drugs are briefly described, too.

Stereotactic radiofrequency ablation of tumors at the hepatic venous confluence

BACKGROUND

Radiofrequency ablation (RFA) is subject to "heat-sink" effects, particularly for treatment of tumors adjacent to major vessels.

METHODS

In this retrospective study, 104 patients with 137 tumors (40 HCC, 10 ICC and 54 metastatic liver tumors) close to (≤1 cm from) the hepatic venous confluence underwent stereotactic RFA (SRFA) between June 2003 and June 2018. Median tumor size was 3.7 cm (1.4-8.5) for HCC, 6.4 cm (0.5-11) for ICC and 3.8 cm (0.5-13) for metastases. Endpoints comprised safety, local tumor control, overall and disease-free survival.

RESULTS

The overall major complication rate was 16.0% (20/125 ablations), where 8 (40%) were successfully treated by the interventional radiologist in the same anesthetic session and did not prolong hospital stay. 134/137 (97.8%) tumors were successfully ablated at initial SRFA. Local recurrence (LR) developed in 19/137 tumors (13.9%). The median and overall survival (OS) rates at 1-, 3-, and 5- years from the date of the first SRFA were 51.5 months, 73.5%, 67.0%, and 49.7% for HCC, 14.6 months, 60.0%, 32.0% and 32.0% for ICC and 38.1 months, 91.4%, 56.5% and 27.9% for metastatic disease, respectively.

CONCLUSION

SRFA represents a viable alternative to hepatic resection for challenging tumors at the hepatic venous confluence.

A novel internal cold circulation radiofrequency-assisted device for liver transection

PURPOSE

To evaluate the safety and efficacy of a new internal cold circulation bipolar radiofrequency compared with Habib-4X bipolar radiofrequency device in the resection of liver tumors.

METHODS

A total of 85 patients with hepatocellular carcinoma who received radiofrequency-assisted liver resection from February 2017 to January 2020 were retrospectively enrolled in our study, in which 45 patients received the new internal cold circulation bipolar radiofrequency (New-RF) and 40 patients received Habib-4X bipolar radiofrequency (Habib-4X). Primary outcome measures were the speed of liver transection, the width of coagulation tissue, hemorrhage volume, blood transfusion rate, and operation time.

RESULTS

The baseline characteristics of patients in the New-RF and Habib-4X groups had no significant difference (p > 0.05). Compared to Habib-4X, the New-RF had a faster average speed of liver transection (4.81 ± 1.20 cm²/min vs 3.64 ± 1.08 cm²/min, p < 0.001), a narrower width of coagulation tissue (1.42 ± 0.23 cm² vs 1.81 ± 0.20 cm², p < 0.001), a less operation time (55.04 ± 16.12 min vs 64.02 ± 15.09 min, p = 0.010), a lower rate of needle path bleeding (13.3% vs 35.0%, p = 0.019), and a lower carbonization rate of electrode needle (22.2% vs 77.8%, p < 0.001). Hemorrhage during the transection (85.0 ml vs 105.0 ml, p = 0.438) and hemorrhage per square centimeter (3.28 ± 0.86 ml/cm² vs 3.60 ± 1.12 ml/cm², p = 0.141) in the New-RF group were smaller than those in Habib-4X group with no significant difference.

CONCLUSION

The new internal cold circulation bipolar radiofrequency was a safe and efficacious auxiliary device for liver resection with a faster speed of resection, lower carbonization rate of electrode needle, and more precise range of coagulation.

Percutaneous radiofrequency ablation of HCC: reduced ablation duration and increased ablation size using single, internally cooled electrodes with an optimized pulsing algorithm

PURPOSE

To assess the use of optimized radiofrequency (RF) to achieve larger, spherical ablation volumes with short application duration for hepatocellular carcinoma (HCC).

MATERIALS AND METHODS

Twenty-two patients (M:F = 17:5, median age 69.6 year, range 63-88) with 28 HCCs due to HCV + liver cirrhosis underwent RFA. 20/28 (71.4%) were tumors ≤3cm diameter, and 8/28 (28.6%) ranged from 3.2 to 4.2 cm. RF was applied using up to 2500mA via an optimized pulsing algorithm with real-time ultrasound monitoring to detect hyperechogenic changes. Single insertions of an internally cooled electrode were performed using exposed tips of 2 or 3 cm for 13 HCCs and 4 cm for 15 HCCs. All patients were followed-up for a minimum of 5 years with contrast-enhanced computed tomography (CECT).

RESULTS

Technical success was achieved without adverse events in all cases. The mean ablation time was 8.5 ± 2.6 min. In 21/28 (75%), ablation duration ranged from 3 to 9 min, with 12 min duration applied in only 7/28 (25%). Mean coagulation diameters were 2.4 ± 0.14, 3.3 ± 0.62, and 4.4 ± 1.0, for 2, 3 and 4 cm electrodes, respectively (p < 0.01). The sphericity index was 74.9 ± 12.8 for 4 cm electrodes and 81.9 ± 8.0 for shorter electrodes (p = 0.091). At 5-year follow-up, no tumor ≤3 cm had recurrence and only 2/8 (25%) >3 cm tumors developed local progression. One patient had multifocal disease with no local progression.

CONCLUSION

Efficient delivery of RF energy can considerably decrease the ablation time in many instances while achieving larger, relatively spherical, and reproducible areas of ablation with extremely low rates of local tumor progression and adverse events.

Challenges Facing Percutaneous Ablation in the Treatment of Hepatocellular Carcinoma: Extension of Ablation Criteria

As an emerging minimally invasive treatment method, percutaneous ablation is more and more widely used in the treatment of liver tumors. It has been recommended by guidelines for diagnosis and treatment of hepatocellular carcinoma (HCC) as a curative treatment alongside surgical resection and liver transplantation. In recent years, with the continuous advancement and innovation of percutaneous ablation technologies, their clinical efficacy and safety have been significantly improved, which has led to the expanded application of percutaneous ablation in the treatment of HCC—more and more patients who were previously considered unsuitable for ablation therapies are now being treated with percutaneous ablation. Obviously, percutaneous ablation can reduce the risk of treatment changes from curative strategies to palliative strategies. Based on clinical practice experience, this review enumerates the advantages and disadvantages of different ablative modalities and summarizes the existing combinations of ablation techniques, thus will help clinicians choose the most appropriate ablative modality for each patient and will provide scientific guidance for improving prognosis and making evidence-based treatment decisions. In addition, we point out the challenges and future prospects of the ablation therapies, thereby providing direction for future research.

Thermal and thermal damage responses during switching bipolar radiofrequency ablation employing bipolar needles: A computational study on the effects of different electrode configuration, input voltage and ablation duration

Recent studies have demonstrated the effectiveness of switching bipolar radiofrequency ablation (bRFA) in treating liver cancer. Nevertheless, the clinical use of the treatment remains less common than conventional monopolar RFA - likely due to the lack of understanding of how the tissues respond thermally to the switching effect. The problem is exacerbated by the numerous possible switching combinations when bRFA is performed using bipolar needles, thus making theoretical deduction and experimental studies difficult. This article addresses this issue via computational modelling by examining if significant variation in the treatment outcome exists amongst six different electrode configurations defined by the X-, C-, U-, N-, Z- and O-models. Results indicated that the tissue thermal and thermal damage responses varied depending on the electrode configuration and the operating conditions (input voltage and ablation duration). For a spherical tumour, 30 mm in diameter, complete ablation could not be attained in all configurations with 70 V input voltage and 5 minutes ablation duration. Increasing the input voltage to 90 V enlarged the coagulation zone in the X-model only. With the other configurations, extending the ablation duration to 10 minutes was found to be the better at enlarging the coagulation zone.

Long-Term Outcomes of Transarterial Chemoembolization Combined with Radiofrequency Ablation Versus Transarterial Chemoembolization Alone for Recurrent Hepatocellular Carcinoma After Surgical Resection

BACKGROUND

There is lack of data for identifying optimal local therapy for the management of recurrent hepatocellular carcinoma (HCC) after hepatic resection.

AIMS

A retrospective study was performed to compare the effectiveness of transarterial chemoembolization (TACE) plus radiofrequency ablation (RFA) with that of TACE alone for recurrent HCC.

METHODS

From 2007 to 2013, patients with recurrent HCC ≤ 5 cm were treated with either TACE plus RFA (n = 96) or TACE (n = 63). Inverse probability of treatment weighting was used to make allowances for imbalances in treatment assignment. The disease-free survival (DFS) and overall survival (OS) were retrospectively analyzed.

RESULTS

The TACE group had lower pretreatment Child-Pugh class (P = 0.025) and shorter pretreatment interval of recurrence (P = 0.028). The 1-, 3-, and 5-year DFS rates for the TACE-RFA group were 55.1%, 22.5%, and 9.7%, respectively, and 41.1%, 9.9%, and 4.9%, respectively, for the TACE group. The OS rates at 1, 3, and 5 years were 82.3%, 42.7%, and 16.5%, respectively, in the TACE-RFA group, and 75.9%, 30.7%, and 11.3%, respectively, in the TACE group. Cirrhosis was significantly associated with disease progression (hazard ratio [HR] 1.53; 95% CI 1.09-2.14; P = 0.014).

CONCLUSIONS

In patients with recurrent HCC ≤ 5 cm, TACE-RFA shows better DFS than TACE alone as a first-line local therapy.

Evaluation of laser-induced plasma ablation focusing on the difference in pulse duration

A pulsed laser cause vaporization of tissue by plasma if a laser can provide high-density energy within a very short pulse duration. Such phenomena are called laser-induced plasma ablation. The influence of the laser-induced plasma ablation for tissue is unclear because the ablation mechanism is differing regardless of two lasers provide almost the same power density. The two kinds of lasers' vaporization mechanism (Nanosecond laser output could cause an optical breakdown in the air depending on power density and pulse duration of the laser and Femtosecond laser output could cause a breakdown only on solids surface since pulse irradiation time is shorter than energy transfer time) are evaluated by using thermal damage and destruction of tissue. The experimental results show that nanosecond laser caused vaporization without thermal damage and destruction at the tissue approximant 300 μm away from the ablation area. The pulsed laser which has high power density and longer pulse duration than energy transfer time is suitable for plasma ablation not depending on thermal process.

Veterinary Clinics: Tumor Ablation

Over the past decade, interventional oncology techniques have become integrated into the treatment plans of companion animals with cancer on a regular basis. Although procedures such as stenting are performed commonly, other less frequently utilized techniques for locoregional therapy, such as embolization and ablation, are emerging and demonstrating promise. Tumor ablation techniques are categorized into two subgroups: chemical ablation and energy-based ablation. Increased utilization of ablation will allow for the determination of specific indications and evaluation of outcomes for these techniques.

Thermal effect of percutaneous radiofrequency ablation with a clustered electrode for vertebral tumors: In vitro and vivo experiments and clinical application

Purpose

To investigate effects and heat distribution of radiofrequency ablation (RFA) on vertebral tumors in vitro and in vivo swine experiments and its clinical application.

Materials and methods

RFA was performed on the swine spine in vitro and in vivo for 20 min at 90 °C at the electrode tip, and the temperature at the electrode tip and surrounding tissues were recorded. Clinical application of ablation combined with vertebroplasty was subsequently performed in 4 patients with spinal tumors.

Results

In the in vitro study, the mean temperature at the front and ventral wall of the spinal canal was 50.8 °C and 43.6 °C, respectively, at 20 mm significantly greater than 37.7 °C and 33.7 ± 1.7 °C, respectively, at 10 mm ablation depth. The coagulative necrosis area was significantly (P < 0.0001) greater at 20 mm depth than at 10 mm depth (mean 17.0 × 20.7 mm² vs. 14.2 × 16.6 mm²). In the in vivo experiment, the local temperature increased significantly (P < 0.05) from around 36 °C before ablation to over 41 °C at 20 min after ablation, with the temperature at the electrode tip (90.4 °C) and within the vertebral body (67.0 °C) significantly (P < 0.05) greater than at the posterior (41.9 °C) and lateral wall (41.8 °C). From 2 to 5 weeks, bone remodeling began. Clinically, all four patients had successful RFA and vertebroplasty, with no neurological deficits. The pain scores were significanlty (P < 0.05) improved before (4.5–10, mean 8.0) compared with at four weeks (0–1.8, mean 1.8).

Conclusion

The clustered electrode can be efficiently and safely applied in the treatment of spinal tumors without damaging the spinal cord and adjacent nerves by heat distribution.

Hepatocellular carcinoma abutting large vessels: comparison of four percutaneous ablation systems

PURPOSE

To compare overall local tumour progression (OLTP), defined as the failure of primary ablation or local tumour progression, with single applicator monopolar radiofrequency ablation (RFA), microwave ablation (MWA), cluster-RFA and multi-bipolar radiofrequency (mbpRFA) in the treatment of hepatocellular carcinoma (HCC) ≤ 5 cm abutting large vessels (≥3 mm).

MATERIALS AND METHODS

This multicenter, retrospective, per-nodule study was performed from 2007 to 2015. The study was approved by the ethics review board, and informed consent was waived. A total of 160/914 HCC nodules treated by thermal ablation and abutting large vessels (40 per treatment group) treated by monopolar RFA, MWA, cluster-RFA or mbpRFA were matched for tumour size, alpha-feto-protein level and vessel size. OLTP rates were compared by the log-rank test and the multivariate Cox model after matching.

RESULTS

No differences were observed in tumour size, vessel size or alpha-feto-protein levels among the three groups (p = 1). The cumulative 4-year OLTP rates following monopolar RFA, cluster-RFA, multi-bipolar RFA and MWA were 50.5%, 16.3%, 16.3% and 44.2%, respectively (p = 0.036). On multivariate Cox regression, vessel size ≥10 mm, monopolar RFA and MWA were independent risk factors of OLTP compared to cluster-RFA or mbpRFA.

CONCLUSION

Multi-applicator RFA provides better local tumour control in HCC abutting large vessels than single-applicator techniques (monopolar RFA or MWA).

Targeted treatment of primary aldosteronism - The consensus of Taiwan Society of Aldosteronism

BACKGROUND/PURPOSE

Even with the increasing recognition of primary aldosteronism (PA) as a cause of refractory hypertension and an issue of public health, the consensus of its optimal surgical or medical treatment in Taiwan has not been reached. Our objective was to develop a clinical practice guideline that is feasible for real-world management of PA patients in Taiwan.

METHODS

The Taiwan Society of Aldosteronism (TSA) Task Force recognized the above-mentioned issues and reached this Taiwan PA consensus at its inaugural meeting, in order to provide updated information of internationally acceptable standards, and also to incorporate our local disease characteristics and constraints into PA management.

RESULTS

In patients with lateralized PA, including aldosterone producing adenoma (APA), laparoscopic adrenalectomy is the 'gold standard' of treatment. Mini-laparoscopic and laparoendoscopic single-site approaches are feasible only in highly experienced surgeons. Patients with bilateral adrenal hyperplasia or those not suitable for surgery should be treated by mineralocorticoid receptor antagonists. The outcome data of PA patient management from the literature, especially from PA patients in Taiwan, are reviewed. Mental health screening is helpful in early detection and management of psychopathology among PA patients.

CONCLUSION

We hope this consensus will provide a guideline to help medical professionals to manage PA patients in Taiwan to achieve a better quality of care.

Magnetic Resonance Mediated Radiofrequency Ablation

To introduce magnetic resonance mediated radiofrequency ablation (MR-RFA), in which the MRI scanner uniquely serves both diagnostic and therapeutic roles. In MR-RFA scanner-induced RF heating is channeled to the ablation site via a Larmor frequency RF pickup device and needle system, and controlled via the pulse sequence. MR-RFA was evaluated with simulation of electric and magnetic fields to predict the increase in local specific-absorption-rate (SAR). Temperature-time profiles were measured for different configurations of the device in agar phantoms and ex vivo bovine liver in a 1.5 T scanner. Temperature rise in MR-RFA was imaged using the proton resonance frequency method validated with fiber-optic thermometry. MR-RFA was performed on the livers of two healthy live pigs. Simulations indicated a near tenfold increase in SAR at the RFA needle tip. Temperature-time profiles depended significantly on the physical parameters of the device although both configurations tested yielded temperature increases sufficient for ablation. Resected livers from live ablations exhibited clear thermal lesions. MR-RFA holds potential for integrating RF ablation tumor therapy with MRI scanning. MR-RFA may add value to MRI with the addition of a potentially disposable ablation device, while retaining MRI's ability to provide real time procedure guidance and measurement of tissue temperature, perfusion, and coagulation.

Perfused hypertonic-saline-augmented needle enlarges ablation zones in ex vivo porcine livers

There is a great clinical requirement to improve radiofrequency ablation (RFA) efficacy and create larger coagulation necrotic areas. The aim of the present study was to assess the ability of a hypertonic-saline (HS)-enhanced multipolar RFA technique using a perfused electrode to increase RF-created coagulation necrosis, and to compare that technique with natural saline-augmented needle and conventional multipolar RFA. A total of 18 ablations were performed in explanted porcine livers. A total of 6 thermal ablation zones were created in each of 3 groups treated with the conventional multipolar mode, the multipolar mode with 0.9% NaCl and the multipolar mode with 6% NaCl, respectively. During RFA, the dimensions and volumes of the ablation zones were compared, and gross and microscopic pathological evaluations were performed. Multipolar RFA with 6% NaCl created the largest short-axis diameters and volumes of coagulation necrosis (3.89±0.09 mm and 40.01±2.86 mm³, respectively) among the three groups (conventional group: 2.31±0.04 mm and 8.99±0.52 mm³, respectively; 0.9% NaCl solution group: 3.17±0.05 mm and 21.79±1.05 mm³, respectively). Overall, multipolar RFA with the instillation of 6% NaCl solution through an open perfusion system created a larger ablation zone compared with the conventional and 0.9% NaCl modes. Therefore, HS-enhanced multipolar RFA may be a promising approach for treating large liver tumors.

Mesoporous composite nanoparticles for dual-modality ultrasound/magnetic resonance imaging and synergistic chemo-/thermotherapy against deep tumors

High-intensity focused ultrasound (HIFU) is a promising and noninvasive treatment for solid tumors, which has been explored for potential clinical applications. However, the clinical applications of HIFU for large and deep tumors such as hepatocellular carcinoma (HCC) are severely limited by unsatisfactory imaging guidance, long therapeutic times, and damage to normal tissue around the tumor due to the high power applied. In this study, we developed doxorubicin/perfluorohexane-encapsulated hollow mesoporous Prussian blue nanoparticles (HMPBs-DOX/PFH) as theranostic agents, which can effectively guide HIFU therapy and enhance its therapeutic effects in combination with chemotherapy, by decreasing the cavitation threshold. We investigated the effects of this agent on ultrasound and magnetic resonance imaging in vitro and in vivo. In addition, we showed a highly efficient HIFU therapeutic effect against HCC tumors, as well as controlled drug release, owing to the phase-transitional performance of the PFH. We therefore conclude that HMPB-DOX/PFH is a safe and efficient nanoplatform, which holds significant promise for cancer theranostics against deep tumors in clinical settings.

Percutaneous Radiofrequency Ablation of Unresectable Locally Advanced Pancreatic Cancer: Preliminary Results

AIM

The objective of this study was to evaluate the efficacy of percutaneous radiofrequency ablation of locally advanced pancreatic cancer located in the pancreatic body.

MATERIALS AND METHODS

Patients with biopsy-proven locally advanced pancreatic adenocarcinoma were considered for percutaneous radiofrequency ablation. Postprocedural computed tomography studies and Ca19.9 tumor marker evaluation were performed at 24 hours and 1 month. At computed tomography, treatment effect was evaluated by excluding the presence of complications. The technical success of the procedure is defined at computed tomography as the achievement of tumoral ablated area.

RESULTS

Twenty-three patients have been included in the study. Five of the 23 patients were excluded. At computed tomography, the mean size of the intralesional postablation necrotic area was 32 mm (range: 15-65 mm). Technical success of the procedure has been obtained in 16 (93%) of the 18 cases. None of the patients developed postprocedural complications. Mean Ca19.9 serum levels 1 day before, 1 day after, and 1 month after the procedure were 285.8 U/mL (range: 16.6-942.0 U/mL), 635.2 U/mL (range: 17.9-3368.0 U/mL), and 336.0 U/mL (range: 7.0-1400.0 U/mL), respectively. Follow-up duration was less than 6 months for 11 patients and more than 6 months for 7 patients. At the time of the draft of this article, the mean survival of the patients included in the study was 185 days (range: 62-398 days).

CONCLUSION

Percutaneous radiofrequency ablation of locally advanced adenocarcinoma has a high technical success rate and is effective in cytoreduction both at imaging and laboratory controls.

[CT Guided Radiofrequency Ablation Followed Intratumoral Chemotherapy in the Treatment of Early Stage Non-small Cell Lung Cancer]

背景与目的

射频消融（radiofrequency ablation, RFA）已经成为无法手术的早期非小细胞肺癌（non-small cell lung cancer, NSCLC）的局部治疗方法之一。本研究观察计算机断层扫描（computed tomography, CT）引导下RFA与瘤内化疗（intratumoral chemotherapy, ITC）（RFA-ITC）的有效性和安全性。

方法

自2005年1月至2015年12月研究组前瞻性入组经病理学证实为早期NSCLC，因心肺功能较差或伴发其他疾病而无法耐受手术或拒绝手术的患者，接受RFA-ITC治疗。RFA采用导向器辅助CT引导穿刺准实时步进法，适形伞状电极、单点或多点消融，完成治疗计划并当CT显示肿瘤周围正常肺组织呈现磨玻璃样后结束消融治疗，经电极针将卡铂200 mg缓慢注射到肿瘤内。随访评估安全性和有效性。

结果

110例患者125次RFA-ITC治疗，技术成功率为100%。中位生存期为48.0个月，总生存率为55.4个月，无进展生存期为55.1个月；1年、2年、3年、5年总生存率分别为100%、90.7%、62.7%、21.9%。消融后有和无磨玻璃样改变的生存期分别是68.3个月、40.1个月，有统计学差异（P=0.001）。肿瘤的大小及有无N1分期的生存率无差异。无围手术期死亡发生，气胸、肺内出血、胸腔积液、发热、术中胸痛、皮下气肿、术中咳嗽等并发症轻微可耐受。

结论

CT引导RFA-ITC治疗不能手术的早期NSCLC，疗效好、并发症少，对患者损伤小，为不能手术治疗的早期NSCLC的治疗提供了一个良好方法。

Radiofrequency Ablation of Uterine Fibroids: a Review

Laparoscopic, ultrasound-guided radiofrequency ablation (RFA) is a new, FDA-cleared uterine sparing, outpatient procedure for uterine fibroids. The procedure utilizes recent technological advancements in instrumentation and imaging, allowing surgeons to treat numerous fibroids of varying size and location in a minimally invasive fashion. Early and mid-term data from multi-center clinical trials have demonstrated safety and efficacy, with resolution or improvement of symptoms and significant volume reduction. Re-intervention rates for fibroid symptoms have been low. The procedure is well tolerated with a typically uneventful and rapid recovery requiring NSAIDs only for postoperative pain. While post RFA pregnancy data are limited, the results are promising.

Switching Monopolar Radiofrequency Ablation Using a Separable Cluster Electrode in Patients with Hepatocellular Carcinoma: A Prospective Study

OBJECTIVE

This study was conducted to evaluate the outcomes of multi-channel switching RFA using a separable cluster electrode in patients with HCC.

METHODS

From November 2011 to July 2013, 79 patients with 98 HCCs < 5 cm were enrolled and treated with RFA using a multi-channel switching radiofrequency system and a separable cluster electrode under the guidance of a real-time fusion imaging system. The primary and secondary endpoints were the 3-year local tumor progression (LTP) rate and recurrence-free survival (RFS) rate, respectively. For post hoc analyses, LTP, RFS, and major complication rates were retrospectively compared with a historical control group treated with RFA using the same radiofrequency system but with multiple internally-cooled electrodes.

RESULTS

The technique success rate of the 98 tumors was 100%. Cumulative 1-year, 2-year, and 3-year LTP rates were 3.4%, 6.9%, and 12.4%, respectively. For patient-level data, cumulative 1-year, 2-year, and 3-year RFS rates were 83.9%, 68.6%, and 45.4%, respectively. On post hoc analyses, none of the baseline characteristics showed a significant difference between the separable cluster electrode and multiple internally-cooled electrodes group. Cumulative LTP and RFS rates of the two groups also showed no significant difference (p = 0.401 and p = 0.881, respectively). Finally, major complication rates of the separable cluster electrode group (5.0%, 4/79) and multiple internally-cooled electrodes group (5.9%, 4/74) were also comparable (p = 1.000).

CONCLUSION

Switching monopolar RFA using a separable cluster electrode is a feasible and efficient technique for the treatment of HCCs smaller than 5 cm, providing comparable local tumor control to multiple internally-cooled electrodes.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02745483.

A review of radiofrequency ablation: Large target tissue necrosis and mathematical modelling

Radiofrequency ablation (RFA) is an effective clinical method for tumour ablation with minimum intrusiveness. However, the use of RFA is mostly restricted to small tumours, especially those <3cm in diameter. This paper discusses the state-of-the-art of RFA, drawn from experimental and clinical results, for large tumours (i.e. ⩾3cm in diameter). In particular, the paper analyses clinical results related to target tissue necrosis (TTN) and mathematical modelling of the RFA procedure to understand the mechanism whereby the TTN is limited to under 3cm with RFA. This paper also discusses a strategy of controlling of the temperature of target tissue in the RFA procedure with the state-of-art device, which has the potential to increase the size of TTN. This paper ends with a discussion of some future ideas to solve the so-called 3-cm problem with RFA.

Nanoparticle-enhanced synergistic HIFU ablation and transarterial chemoembolization for efficient cancer therapy

High-intensity focused ultrasound (HIFU) is being generally explored as a non-invasive therapeutic modality to treat solid tumors. However, the clinical use of HIFU for large and deep tumor-ablation applications such as hepatocellular carcinoma (HCC) is currently entangled with long treatment duration and high operating energy. This critical issue can be potentially resolved by the introduction of HIFU synergistic agents (SAs). Traditional SAs such as microbubbles and microparticles face the problem of large size, short cycle time, damage to mononuclear phagocytic system and unsatisfactory targeting efficiency. In this work, we have developed a facile and versatile nanoparticle-based HIFU synergistic cancer surgery enhanced by transarterial chemoembolization for high-efficiency HCC treatment based on elaborately designed Fe3O4-PFH/PLGA nanocapsules. Multifunctional Fe3O4-PFH/PLGA nanocapsules were administrated into tumor tissues via transarterial injection combined with Lipiodol to achieve high tumor accumulation because transarterial chemoembolization by Lipiodol could block the blood vessels. The high synergistic HIFU ablation effect was successfully achieved against HCC tumors based on the phase-transformation performance of the perfluorohexane (PFH) inner core in the composite nanocapsules, as systematically demonstrated in VX2 liver tumor xenograft in rabbits. Multifunctional Fe3O4-PFH/PLGA nanocapsules were also demonstrated as efficient contrast agents for ultrasound, magnetic resonance and photoacoustic tri-modality imagings, potentially applicable for imaging-guided HIFU synergistic surgery. Therefore, the elaborate integration of traditional transarterial chemoembolization with recently developed nanoparticle-enhanced HIFU cancer surgery could efficiently enhance the HCC cancer treatment outcome, initiating a new and efficient therapeutic protocol/modality for clinic cancer treatment.

Trimodal Therapy: Combining Hyperthermia with Repurposed Bexarotene and Ultrasound for Treating Liver Cancer

Repurposing of existing cancer drugs to overcome their physical limitations, such as insolubility, represents an attractive strategy to achieve enhanced therapeutic efficacy and broaden the range of clinical applications. Such an approach also promises to offer substantial cost savings in drug development efforts. Here we repurposed FDA-approved topical agent bexarotene (Targretin), currently in limited use for cutaneous manifestations of T-cell lymphomas, and re-engineer it for use in solid tumor applications by forming self-assembling nanobubbles. Physico-chemical characterization studies of the novel prodrug nanobubbles demonstrated their stability, enhanced target cell internalization capability, and highly controlled release profile in response to application of focused ultrasound energy. Using an in vitro model of hepatocellular carcinoma and an in vivo large animal model of liver ablation, we demonstrate the effectiveness of bexarotene prodrug nanobubbles when used in conjunction with catheter-based ultrasound, thereby highlighting the therapeutic promise of this trimodal approach.

Percutaneous tumor ablation tools: microwave, radiofrequency, or cryoablation--what should you use and why?

Image-guided thermal ablation is an evolving and growing treatment option for patients with malignant disease of multiple organ systems. Treatment indications have been expanding to include benign tumors as well. Specifically, the most prevalent indications to date have been in the liver (primary and metastatic disease, as well as benign tumors such as hemangiomas and adenomas), kidney (primarily renal cell carcinoma, but also benign tumors such as angiomyolipomas and oncocytomas), lung (primary and metastatic disease), and soft tissue and/or bone (primarily metastatic disease and osteoid osteomas). Each organ system has different underlying tissue characteristics, which can have profound effects on the resulting thermal changes and ablation zone. Understanding these issues is important for optimizing clinical results. In addition, thermal ablation technology has evolved rapidly during the past several decades, with substantial technical and procedural improvements that can help improve clinical outcomes and safety profiles. Staying up to date on these developments is challenging but critical because the physical properties underlying the different ablation modalities and the appropriate use of adjuncts will have a tremendous effect on treatment results. Ultimately, combining an understanding of the physical properties of the ablation modalities with an understanding of the thermal kinetics in tissue and using the most appropriate ablation modality for each patient are key to optimizing clinical outcomes. Suggested algorithms are described that will help physicians choose among the various ablation modalities for individual patients.

Percutaneous tumor ablation tools: microwave, radiofrequency, or cryoablation--what should you use and why?

Image-guided thermal ablation is an evolving and growing treatment option for patients with malignant disease of multiple organ systems. Treatment indications have been expanding to include benign tumors as well. Specifically, the most prevalent indications to date have been in the liver (primary and metastatic disease, as well as benign tumors such as hemangiomas and adenomas), kidney (primarily renal cell carcinoma, but also benign tumors such as angiomyolipomas and oncocytomas), lung (primary and metastatic disease), and soft tissue and/or bone (primarily metastatic disease and osteoid osteomas). Each organ system has different underlying tissue characteristics, which can have profound effects on the resulting thermal changes and ablation zone. Understanding these issues is important for optimizing clinical results. In addition, thermal ablation technology has evolved rapidly during the past several decades, with substantial technical and procedural improvements that can help improve clinical outcomes and safety profiles. Staying up to date on these developments is challenging but critical because the physical properties underlying the different ablation modalities and the appropriate use of adjuncts will have a tremendous effect on treatment results. Ultimately, combining an understanding of the physical properties of the ablation modalities with an understanding of the thermal kinetics in tissue and using the most appropriate ablation modality for each patient are key to optimizing clinical outcomes. Suggested algorithms are described that will help physicians choose among the various ablation modalities for individual patients.

Current status and prospective of imaging guided radiofrequency ablation in medium to large sized hepatocellular carcinomas

The incidence of liver cancer is high in China and effective treatments are required. Recently, imaging guided radiofrequency ablation (RFA) has become increasingly accepted in treating solid tumors because of minimal invasiveness, easy operation and effectiveness. The outcome of RFA in small liver tumors is even comparable to that of surgery. However, the RFA efficacy in larger ( > 3.0 cm) liver tumors is not satisfactory and recurrence after treatment is common. The development of basic research and RFA device has provided more opportunities for us to treat>3.0 cm liver tumors. The successful ablation of solid tumors relies on three key components, the technology (i.e., the RFA generator and electrodes selected), the biology of the tumor and background tissue, and operator factors. The current development and prospective of the three main elements will be the focus in this review.

Thermal tumor ablation in clinical use

Although a surgical procedure is performed by visual inspection with histopathological assessment of the excised tumor and margins, percutaneous and noninvasive thermal ablation is performed strictly with the aid of imaging. Applicator guidance into the target zone, treatment monitoring and verification, and clinical follow-up rely on effective imaging. Detailed discussion of imaging is beyond the scope of this article, but the influence of imaging on the choice of thermal ablation or procedural approach will be discussed as needed. More information on imaging for interventional therapies can be found in other articles in this issue of IEEE Pulse.

Effect of Nonparallel Placement of In-Circle Bipolar Radiofrequency Ablation Probes on Volume of Tissue Ablated With Heat Sink

Objectives. Percutaneous bipolar radiofrequency ablation (RFA) is a minimally invasive technique for treating liver tumors. It is not always possible to insert the bipolar probes parallel to each other on either side of tumor, since it restricts maneuverability away from vital structures or ablate certain tumor shape. Therefore, we investigated how nonparallel placement of probes affected ablation. Methods. Bipolar RFA in parallel and in divergent positions were submerged in tissue model (800 mL egg white) at 37°C and ablated. Temperature probes, T1 and T2 were placed 8.00 mm below the tip of the probes, T3 in between the probe coil elements and T4 and T5 at water inlet and outlet, respectively. Both models with heat sink (+HS) and without (−HS) were investigated. Results. The mean ablated tissue volume, mass, density and height increased linearly with unit angle increase for −HS model. With +HS, a smaller increase in mean volume and mass, a slightly greater increase in mean density but a reduction in height of tissue was seen. The mean ablation time and duration of maximum temperature with +HS was slightly larger, compared with −HS, while −HS ablated at a slightly higher temperature. The heat sink present was minimal for probes in parallel position compared to nonparallel positions. Conclusion. Divergence from parallel insertion of bipolar RFA probes increased the mean volume, mass, and density of tissue ablated. However, the presence of large heat sinks may limit the application of this technique, when tumors border on larger vessels.

Intermediate hepatocellular carcinoma: How to choose the best treatment modality?

Intermediate stage, or stage B according to Barcelona Clinic Liver Cancer classification, of hepatocellular carcinoma (HCC) comprises a heterogeneous population with different tumor burden and liver function. This heterogeneity is confirmed by the large variability of treatment choice and disease-relate survival. The aim of this review was to highlight the existing evidences regarding this specific topic. In a multidisciplinary evaluation, patients with large (> 5 cm) solitary HCC should be firstly considered for liver resection (LR). When LR is unfeasible, locoregional treatments are evaluable therapeutic options, being transarterial chemoembolization (TACE), the most used procedure. Percutaneous ablation can be an evaluable treatment for large HCC. However, the efficacy of all ablative procedures decrease as tumor size increases over 3 cm. In clinical practice, a combination treatment strategy [TACE or transarterial radioembolization (TARE)-plus percutaneous ablation] is “a priori” preferred in a relevant percentage of these patients. On the other hands, sorafenib is the treatment of choice in patients who are unsuitable to surgery and/or with a contraindication to locoregional treatments. In multifocal HCC, TACE is the first-line treatment. The role of TARE is still undefined. Surgery may have also a role in the treatment of multifocal HCC in selected cases (patients with up to three nodules, multifocal HCC involving 2-3 adjacent liver segments). In some patients with bilobar disease the combination of LR and ablative treatment may be a valuable option. The choice of the best treatment in the patient with intermediate stage HCC should be “patient-tailored” and made by a multidisciplinary team.

Thermal ablation of colorectal liver metastases: a position paper by an international panel of ablation experts, The Interventional Oncology Sans Frontières meeting 2013

Objectives

Previous attempts at meta-analysis and systematic review have not provided clear recommendations for the clinical application of thermal ablation in metastatic colorectal cancer. Many authors believe that the probability of gathering randomised controlled trial (RCT) data is low. Our aim is to provide a consensus document making recommendations on the appropriate application of thermal ablation in patients with colorectal liver metastases.

Methods

This consensus paper was discussed by an expert panel at The Interventional Oncology Sans Frontières 2013. A literature review was presented. Tumour characteristics, ablation technique and different clinical applications were considered and the level of consensus was documented.

Results

Specific recommendations are made with regard to metastasis size, number, and location and ablation technique. Mean 31 % 5-year survival post-ablation in selected patients has resulted in acceptance of this therapy for those with technically inoperable but limited liver disease and those with limited liver reserve or co-morbidities that render them inoperable.

Conclusions

In the absence of RCT data, it is our aim that this consensus document will facilitate judicious selection of the patients most likely to benefit from thermal ablation and provide a unified interventional oncological perspective for the use of this technology.

Key Points

• Best results require due consideration of tumour size, number, volume and location.

• Ablation technology, imaging guidance and intra-procedural imaging assessment must be optimised.

• Accepted applications include inoperable disease due to tumour distribution or inadequate liver reserve.

• Other current indications include concurrent co-morbidity, patient choice and the test-of-time approach.

• Future applications may include resectable disease, e.g. for small solitary tumours.

Hepatic radiofrequency ablation: in vivo and ex vivo comparisons of 15-gauge (G) and 17-G internally cooled electrodes

OBJECTIVE

To compare the performance of the 15-G internally cooled electrode with that of the conventional 17-G internally cooled electrode.

METHODS

A total of 40 (20 for each electrode) and 20 ablation zones (10 for each electrode) were made in extracted bovine livers and in in vivo porcine livers, respectively. Technical parameters, three dimensions [long-axis diameter (Dl), vertical-axis diameter (Dv) and short-axis diameter (Ds)], volume and the circularity (Ds/Dl) of the ablation zone were compared.

RESULTS

The total delivered energy was higher in the 15-G group than in the 17-G group in both ex vivo and in vivo studies (8.78 ± 1.06 vs 7.70 ± 0.98 kcal, p = 0.033; 11.20 ± 1.13 vs 8.49 ± 0.35 kcal, p = 0.001, respectively). The three dimensions of the ablation zone had a tendency to be larger in the 15-G group than in the 17-G group in both studies. The ablation volume was larger in the 15-G group than in the 17-G group in both ex vivo and in vivo studies (29.61 ± 7.10 vs 23.86 ± 3.82 cm(3), p = 0.015; 10.26 ± 2.28 vs 7.79 ± 1.68 cm(3), p = 0.028, respectively). The circularity of ablation zone was not significantly different in both the studies.

CONCLUSION

The size of ablation zone was larger in the 15-G internally cooled electrode than in the 17-G electrode in both ex vivo and in vivo studies.

ADVANCES IN KNOWLEDGE

Radiofrequency ablation of hepatic tumours using 15-G electrode is useful to create larger ablation zones.

Heat sink effect on tumor ablation characteristics as observed in monopolar radiofrequency, bipolar radiofrequency, and microwave, using ex vivo calf liver model

Thermal ablation of liver tumors near large blood vessels is affected by the cooling effect of blood flow, leading to incomplete ablation. Hence, we conducted a comparative investigation of heat sink effect in monopolar (MP) and bipolar (BP) radiofrequency ablation (RFA), and microwave (MW) ablation devices.With a perfused calf liver, the ablative performances (volume, mass, density, dimensions), with and without heat sink, were measured. Heat sink was present when the ablative tip of the probes were 8.0 mm close to a major hepatic vein and absent when >30 mm away. Temperatures (T1 and T2) on either side of the hepatic vein near the tip of the probes, heating probe temperature (T3), outlet perfusate temperature (T4), and ablation time were monitored.With or without heat sink, BP radiofrequency ablated a larger volume and mass, compared with MP RFA or MW ablation, with latter device producing the highest density of tissue ablated. MW ablation produced an ellipsoidal shape while radiofrequency devices produced spheres.Percentage heat sink effect in Bipolar radiofrequency : Mono-polar radiofrequency : Microwave was (Volume) 33:41:22; (mass) 23:56:34; (density) 9.0:26:18; and (relative elipscity) 5.8:12.9:1.3, indicating that BP and MW devices were less affected.Percentage heat sink effect on time (minutes) to reach maximum temperature (W) = 13.28:9.2:29.8; time at maximum temperature (X) is 87:66:16.66; temperature difference (Y) between the thermal probes (T3) and the temperature (T1 + T2)/2 on either side of the hepatic vessel was 100:87:20; and temperature difference between the (T1 + T2)/2 and temperature of outlet circulating solution (T4), Z was 20.33:30.23:37.5.MW and BP radiofrequencies were less affected by heat sink while MP RFA was the most affected. With a single ablation, BP radiofrequency ablated a larger volume and mass regardless of heat sink.

Image-guided tumor ablation: standardization of terminology and reporting criteria--a 10-year update

Image-guided tumor ablation has become a well-established hallmark of local cancer therapy. The breadth of options available in this growing field increases the need for standardization of terminology and reporting criteria to facilitate effective communication of ideas and appropriate comparison among treatments that use different technologies, such as chemical (eg, ethanol or acetic acid) ablation, thermal therapies (eg, radiofrequency, laser, microwave, focused ultrasound, and cryoablation) and newer ablative modalities such as irreversible electroporation. This updated consensus document provides a framework that will facilitate the clearest communication among investigators regarding ablative technologies. An appropriate vehicle is proposed for reporting the various aspects of image-guided ablation therapy including classification of therapies, procedure terms, descriptors of imaging guidance, and terminology for imaging and pathologic findings. Methods are addressed for standardizing reporting of technique, follow-up, complications, and clinical results. As noted in the original document from 2003, adherence to the recommendations will improve the precision of communications in this field, leading to more accurate comparison of technologies and results, and ultimately to improved patient outcomes.

Image-guided tumor ablation: standardization of terminology and reporting criteria--a 10-year update

Image-guided tumor ablation has become a well-established hallmark of local cancer therapy. The breadth of options available in this growing field increases the need for standardization of terminology and reporting criteria to facilitate effective communication of ideas and appropriate comparison among treatments that use different technologies, such as chemical (eg, ethanol or acetic acid) ablation, thermal therapies (eg, radiofrequency, laser, microwave, focused ultrasound, and cryoablation) and newer ablative modalities such as irreversible electroporation. This updated consensus document provides a framework that will facilitate the clearest communication among investigators regarding ablative technologies. An appropriate vehicle is proposed for reporting the various aspects of image-guided ablation therapy including classification of therapies, procedure terms, descriptors of imaging guidance, and terminology for imaging and pathologic findings. Methods are addressed for standardizing reporting of technique, follow-up, complications, and clinical results. As noted in the original document from 2003, adherence to the recommendations will improve the precision of communications in this field, leading to more accurate comparison of technologies and results, and ultimately to improved patient outcomes. Online supplemental material is available for this article .

A comparison of internally water-perfused and cryogenically cooled monopolar and bipolar radiofrequency applicators in ex vivo liver samples

RATIONALE AND OBJECTIVES

To evaluate the ex vivo ablation zones created in hepatic tissue using monopolar and bipolar gas- and water-cooled radiofrequency (RF) applicators.

MATERIALS AND METHODS

RF ablations were performed on ex vivo bovine liver tissue using closed circuit water-cooled and closed circuit cryogenically cooled (via CO₂ enthalpy) 15-ga linear-needle applicators. Both monopolar and bipolar electrode applicators were used, with the electric current administered ranging in 50-mA increments from 1100 to 1300 mA for the monopolar case, and from 500 to 700 mA for the bipolar case. Total ablation time was 15 minutes. Six tissue samples were ablated per setting. The ablated volumes were assumed to have a three-dimensional ellipsoid shape, with one long major axis and two smaller minor axes. Gross histology was used to measure the dimensions of the ablated regions to quantify the ablated volume, the dimensions of the axis, and the ratio between the long axis and the smallest minor axis, which was termed the ellipticity index.

RESULTS

The gas-cooled monopolar applicator achieved the largest short-axis ablation diameter (4.05 ± 0.4 cm), followed by the water-cooled monopolar applicator (3.18 ± 0.29 cm). With the bipolar applicator, the gas-cooled applicators also achieved larger short-axis ablation diameters (3.02 ± 0.15 cm) than the water-cooled applicators (2.72 ± 0.29 cm). The gas-cooled monopolar applicator also provided the largest ablation volume (42.7 ± 10.7 mL) and the most spherically shaped lesions (ellipticity index: 1.21 ± 0.10). Lesion size increased with injected current up to a threshold current of 1200/1250 mA (monopolar water-/gas-cooled) and 600/650 mA (bipolar water-/gas-cooled), but dropped at greater values.

CONCLUSIONS

Gas-cooled monopolar applicators were superior to the other tested applicators in terms of both volume and sphericity of the ablation zone.