热消融在肺癌中的应用和展望

肺癌作为高发病率和高致死率的恶性肿瘤,严重影响人类的健康。目前,外科手术、化学治疗、放射治疗、分子靶向治疗和基因治疗等均是肺癌治疗和提高预后的主要手段。热消融作为肺癌治疗的新兴手段,因其微创、安全、可靠已经引起广泛的关注。文章主要回顾射频消融和微波消融在肺癌中的应用,比较几种不同治疗方式并对热消融在肺癌中的应用做出展望。     

Chemical ablation of liver cancer

Percutaneous chemical ablation is an established image-guided therapy for liver cancer that is relatively simple to perform and requires no specialized equipment. Chemical ablation has been used extensively for hepatocellular carcinoma (HCC), and has achieved outcomes comparable to surgical resection for small, solitary HCC. More recent experience with chemical ablation has combined it with TACE or thermal ablation as part of a multimodality approach to liver cancer.     

Internally gas-cooled radiofrequency applicators as an alternative to conventional radiofrequency and microwave ablation devices: An in vivo comparison

Purpose

To test the efficacy of internally CO₂-cooled radiofrequency (RF) ablation in vivo and to compare its effectiveness to a standard water-cooled RF probe and to a gas-cooled microwave (MW) device.

Method and materials

49 ablations were performed on 15 pigs under general anesthesia using 15G monopolar CO₂-cooled RF applicators, 17G monopolar water-cooled RF applicators and 15G internally CO₂-cooled microwave devices. The power of the MW device was 45 W, the current of the gas-cooled RF device was 1200–1600 mA. At the water-cooled RF probe, maximum power of 200 W was set. Ablation time was 15 min. The short and long axes of the ablation zone were measured. Histological analyses and NADH-staining were performed. The diameters and the ablation volumes were compared using an analysis of variance.

Results

No spots of untreated tissue were observed close to the cooled needle track in any of the ablation zones. The largest short axis diameter was 3.4 ± 0.5 cm achieved with the gas-cooled monopolar applicator. With the water-cooled applicators, short axis diameter was significantly smaller, reaching 2.5 ± 0.4 cm. Gas-cooled MW probes achieved 2.9 ± 1.0 cm. The largest ablation volume was 31.5 ± 12 ml (gas-cooled RF), and the smallest was 12.7 ± 4 ml (water-cooled RF). Short/long axis ratio was largest for gas-cooled RF probes with 0.73 ± 0.08 versus 0.64 ± 0.04 for the water-cooled probes and 0.49 ± 0.25 for the microwave applicator.

Conclusion

Gas-cooled RF applicators may have a higher potential for effective destruction of liver lesions than comparable water-cooled RF systems, and may be an alternative to standard RF and MW ablation devices.     

Ultrasound-guided microwave ablation of hepatocellular carcinoma: Initial institutional experience

BackgroundMicrowave ablation (MWA) is a new treatment modality for hepatocellular carcinoma (HCC) at our institution. The aim of this study is to evaluate the safety, procedure time and rate of complete ablation of this new modality.Material and methodsHospital medical ethics committee approval and informed consent were obtained. A total of 98 nodules in 72 patients (59 male, 13 female; mean age 57 (±4.6) years, range 50–70 years) with HCC were treated with microwave ablation at our institution from June 2010 to February 2011. A 14 G cooled shaft Amica probe was introduced into the tumors under analgesic sedation and by US guidance. The patients were then followed up with contrast enhanced computed tomography (CT) and serum α-fetoprotein levels.ResultsOne month after therapy, complete ablation was obtained in 96% (94/98) nodules. The complete ablation rate in tumors ?3 cm and those >3 cm were 98%, and 94%, respectively. MW ablation success was higher with nodules ?3 cm (57/58, 98.3%) in comparison to nodules >3 cm (37/40, 92.5%): however, the difference was non-significant (P = 0.301). No complication occurred related to the ablation procedure, only minor complications post-ablation, as pain in (3/72) patients, mild fever in (48/72) patients, and discharge from wound in (2/72) patients. No local recurrence was detected, however, new lesions at other sites of the liver occurred in 11 (15%) patients.ConclusionSonographically guided percutaneous microwave ablation proved to be safe, fast, and effective for treatment of hepatocellular carcinoma.     

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/=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/=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.     

Thermal ablation of lung tumors

Thermal ablation can be applied to treat any thoracic malignancy: primary lung cancers, recurrent primary lung cancers, metastatic disease, chest wall masses, and painful, bony metastases. Since the first reported use of thermal ablation for lung cancer in 2000 there has been an explosive use of the procedure, and by 2010 the number of procedures to treat thoracic malignancy is expected to exceed 150,000 per year. Presently, thermal ablation is best used for patients with early-stage lung cancers in patients who are not surgical candidates, patients with small and favorably located pulmonary metastases, and patients in whom palliation of tumor-related symptoms is the goal. Radiofrequency ablation, microwave ablation, and cryoablation are novel treatment modalities for lung cancer and can safely accomplish tumor destruction and even complete eradication of tumor in patients who are not candidates for surgical resection. In this article, we discuss technical considerations for each modality and the periprocedure and postprocedure management of patients with this disease.     

Thermal Ablation for Benign Thyroid Nodules: Radiofrequency and Laser

Although ethanol ablation has been successfully used to treat cystic thyroid nodules, this procedure is less effective when the thyroid nodules are solid. Radiofrequency (RF) ablation, a newer procedure used to treat malignant liver tumors, has been valuable in the treatment of benign thyroid nodules regardless of the extent of the solid component. This article reviews the basic physics, techniques, applications, results, and complications of thyroid RF ablation, in comparison to laser ablation.     

Ultrasonography-guided percutaneous radiofrequency ablation of hepatocellular carcinomas: A feasibility scoring system for planning sonography

Purpose

This study was designed to evaluate whether a feasibility scoring system for planning sonography is a reliable predictor of a safe and complete ablation in ultrasonography (US)-guided percutaneous radiofrequency ablation (RFA) of hepatocellular carcinomas (HCCs).

Materials and methods

We retrospectively evaluated the therapeutic outcomes of 108 consecutive patients (M:F, 78:30; mean age, 57.4 years) with a single nodular HCC (mean diameter, 2.0 cm) treated by percutaneous RFA. All patients were assessed for the feasibility of performing an RFA at planning sonography prior to the ablation. The feasibility scoring system consisted of five categories: the safe electrode path (P); the vital organs adjacent to the RFA zone (O); tumor size (S); tumor conspicuity (C); and the heat-sink effect (H). Each category was divided into a four-point scale [1-4]. If a score of 4 in any category was determined, the patient was not considered to be a suitable candidate for percutaneous RFA. We assessed if the score of each category, safety score (P + O), and curability score (S + C + H) correlated with a safe and complete ablation using the chi-squared test and likelihood ratio test for trend.

Results

The technical success rate was 100% (108/108) based on CT images obtained immediately after ablation. There was no 30-day mortality after RFA. There were major complications (one case of severe vasovagal reflex, one case of hemoperitoneum and one case of a pseudoaneurysm) in three (2.7%) patients, and minor complications (one case of a biloma, one case of subsegmental infarction and one case of abscess) in three (2.7%) patients. Post-ablation syndrome as a side effect was noted in 38 (35.1%) of 108 patients. The primary technique effectiveness rate at 1 month was 95.1% (105/108). Local tumor progression was noted in eight (7.6%) of 105 patients during the follow-up period (range, 3.0-11.5 months; median, 5.8 months; mean, 5.7 months). There was no significant single category to predict complication and local tumor progression (Fisher's exact test, p > 0.05). Contrary to the safety score for the probability of complication (p > 0.05), the curability score was significantly associated with the probability of local tumor progression (likelihood ratio test for trend; p = 0.03).

Conclusion

The new feasibility scoring system for planning US can be used as objective criteria to predict therapeutic efficacy rather than the safety of percutaneous RFA of an HCC.     

Radiofrequency ablation of lung metastases: factors influencing success

This paper analyses the factors associated with successful radiofrequency ablation (RFA) of lung metastases. The study group comprised 37 patients [19 female, mean age 61 (34–83)] with 72 metastases who had follow-up CT scans available for analysis and for those with no recurrence >6 months follow-up. Internally cooled electrodes were used in 64 and expandable electrodes in 8. The tumour size and location, electrode type, number of ablations, duration of ablation, year of treatment and tumour contact with vessels larger than 3 mm were recorded. The mean tumour diameter was 1.8 cm (0.4–6.6 cm). Mean follow-up in those without recurrence was 13.1 months (6–48). Recurrence was common in larger tumours, occurring in 7/7 (100%) tumours >3.5 cm compared with 18/65 (28%) ≤ 3.5 cm (P < 0.01). Recurrence occurred in 14/24 (58%) tumours in direct contact with large vessels compared with 11/48 (23%) of the remainder (P = 0.04). On multivariate analysis, size was the dominant feature (P = 0.013); vessel contact and peripheral location did not reach significance (P = 0.056 and 0.054 respectively). Peripheral tumours less than 3.5 cm with no large vessel contact are the optimal tumours for RFA.     

Resection vs thermal ablation of small hepatocellular carcinoma: What's the first choice?

Nowadays, hepatocellular carcinoma (HCC) is frequently diagnosed at an early stage, opening good perspectives to radical treatment by means of liver transplantation, surgical resection, or percutaneous ablation. Liver transplantation is considered the best option, but the lack of liver donors represents a major limitation. Therefore, surgical resection, offering a 5-year-survival rate of over 50%, is considered the first-choice treatment for patients with early stage HCC, whereas percutaneous ablation is usually reserved to patients who are not candidate to surgery. However, in the recent years some trials showed that percutaneous radiofrequency ablation (RFA) can be as effective as surgical resection in terms of overall survival and recurrence-free survival rates in patients with small HCC, and a retrospective comparative study reported 1-, 3-, and 5-year overall survival rates and recurrence-free survival rates significantly better in patients with central HCC measuring 2 cm or smaller treated with RFA than in those treated with surgical resection. RFA is less expensive, less invasive, with lower complication rate and shorter hospital stay than surgical resection, and on the basis of the results of these studies it should be considered the first option in the treatment of very early HCC. However, RFA is size-dependent, so at present the need to achieve an adequate safety margin around the tumor limits to about 2 cm the diameter of the nodules that can be ablated with long-term outcomes comparable to or better than surgical resection. The main goal of the next technical developments of the thermal ablation systems should be the achievement of larger ablation areas with a single needle insertion. In this regard, the recent improvements in microwave energy delivery systems seem to open interesting perspectives to percutaneous microwave ablation, which could become the ablation technique of choice in the next future.     

Thermal Protection with 5% Dextrose Solution Blanket During Radiofrequency Ablation

A serious complication for any thermal radiofrequency ablation is thermal injury to adjacent structures, particularly the bowel, which can result in additional major surgery or death. Several methods using air, gas, fluid, or thermometry to protect adjacent structures from thermal injury have been reported. In the cases presented in this report, 5% dextrose water (D5W) was instilled to prevent injury to the bowel and diaphragm during radiofrequency ablation. Creating an Insulating envelope or moving organs with D5W might reduce risk for complications such as bowel perforation.     

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

The purpose of this study was to evaluate the effectiveness of a newly developed perfused monopolar radiofrequency (RF) probe with an umbrella-shaped array. A perfused umbrella-shaped monopolar RF probe based on a LeVeen electrode (Boston Scientific Corp., Natick, MA, USA) with a 3-cm array diameter was developed. Five different configurations of this electrode were tested: (a) perfusion channel/endhole, (b) perfusion channel/endhole + sideholes, (c) 1 cm insulation removed at the tip, (d) 1 cm insulation removed at the tip + perfusion channel/endhole, and (e) 1 cm insulation removed at the tip + perfusion channel/endhole + sideholes. An unmodified LeVeen electrode served as a reference standard. RF ablations were performed in freshly excised bovine liver using a commercial monopolar RF system with a 200-W generator (RF 3000; Boston Scientific Corp.). Each electrode was tested 10 times applying the vendor’s recommended ablation protocol combined with the preinjection of 2 ml 0.9% saline. Volumes and shapes of the lesions were compared. Lesions generated with the original LeVeen electrode showed a mean volume of 12.74 ± 0.52 cm3. Removing parts of the insulation led to larger coagulation volumes (22.65 ± 2.12 cm3). Depending on the configuration, saline preinjection resulted in a further increase in coagulation volume (25.22 ± 3.37 to 31.28 ± 2.32 cm³). Besides lesion volume, the shape of the ablation zone was influenced by the configuration of the electrode used. We conclude that saline preinjection in combination with increasing the active tip length of the umbrella-shaped LeVeen RF probe allows the reliable ablation of larger volumes in comparison to the originally configured electrode.     

Percutaneous Liver Tumour Ablation: Image Guidance,Endpoint Assessment,and Quality Control

Liver tumour ablation nowadays represents a routine treatment option for patients with primary and secondary liver tumours. Radiofrequency ablation and microwave ablation are the most widely adopted methods, although novel techniques, such as irreversible electroporation, are quickly working their way up. The percutaneous approach is rapidly gaining popularity because of its minimally invasive character, low complication rate, good efficacy rate, and repeatability. However, matched to partial hepatectomy and open ablations, the issue of ablation site recurrences remains unresolved and necessitates further improvement. For percutaneous liver tumour ablation, several real-time imaging modalities are available to improve tumour visibility, detect surrounding critical structures, guide applicators, monitor treatment effect, and, if necessary, adapt or repeat energy delivery. Known predictors for success are tumour size, location, lesion conspicuity, tumour-free margin, and operator experience. The implementation of reliable endpoints to assess treatment efficacy allows for completion-procedures, either within the same session or within a couple of weeks after the procedure. Although the effect on overall survival may be trivial, (local) progression-free survival will indisputably improve with the implementation of reliable endpoints. This article reviews the available needle navigation techniques, evaluates potential treatment endpoints, and proposes an algorithm for quality control after the procedure.     

经皮肾交感神经射频消融术新器械研制及实验研究

目的 探讨新型国产FlashPiontTM多极肾动脉射频消融导管用于经皮肾交感神经射频消融术的可行性及安全性.方法 FlashPiontTM多极肾动脉射频消融导管头端为螺旋形弯曲状,设有4个消融电极.选用健康实验犬10只,均经股动脉鞘管将FlashPiontTM导管送入右肾动脉主干放电消融2次.术后1个月复查肾动脉造影并处死实验犬,作肾动脉交感神经病理学检查.结果 10只实验犬均顺利完成一侧去肾神经术.术后即刻肾动脉造影未见肾动脉狭窄、血栓形成及夹层等并发症;术后1个月复查造影见两侧肾动脉均通畅,未发现肾动脉狭窄、夹层等并发症,组织病理学检查发现肾动脉血管周围交感神经明显坏死.结论 FlashPiontTM多极肾动脉射频消融导管设计合理、操作简单,能安全、有效地消融犬肾交感神经.     

Comparison of two different thermal techniques for the treatment of hepatocellular carcinoma

Purpose

To compare the safety and efficacy of radiofrequency ablation (RFA) and microwave ablation (MWA) in treating hepatocellular carcinoma (HCC) while conforming to the Milan criteria.

Materials and methods

The study was approved by the Institutional Review Board, and informed consent was waived due to the retrospective study design. One hundred ninety-eight patients met the inclusion criteria and were included in the study. Eighty-five patients with 98 lesions received RFA, and 113 patients with 131 lesions underwent MWA. Complete ablation rates, local recurrence rates, disease-free survival rates, cumulative survival rates, and major complications were compared between the two treatment groups.

Results

Complete ablation rates were 99.0% for RFA and 98.5% for MWA (P = 1.000). Local recurrence rates were 5.2% for RFA and 10.9% for MWA (P = 0.127). Disease-free survival rates at 1, 2, 3, and 4 years were 80.3%, 61.8%, 39.5%, and 19.0% in the RFA group and 75.0%, 59.4%, 32.1%, and 16.1% in the MWA group, respectively (P = 0.376). Cumulative survival rates at 1, 2, 3, and 4 years were 98.7%, 92.3%, 82.7%, and 77.8% in the RFA group and 98.0%, 90.7%, 77.6%, and 77.6% in the MWA group, respectively (P = 0.729). Major complication rates were 2.4% and 2.7% in the RFA group and the MWA group, respectively (P = 1.000). There were no patient deaths due to treatment.

Conclusion

RFA and MWA have the same clinical value in treating HCC conforming to the Milan criteria. RFA and MWA are both safe and effective techniques for HCC as clinical application.     

Magnetic resonance guidance for radiofrequency ablation of liver tumors

Image-guided thermal ablation of liver tumors is a minimally invasive treatment option. Techniques used for thermal ablation are radiofrequency (RF) ablation, laser interstitial thermotherapy (LITT), microwave (MW) ablation, high-intensity focused ultrasound (HIFU), and cryoablation. Among these techniques RF ablation attained widespread consideration. Image guidance should ensure a precise ablation therapy leading to a complete coagulation of tumor tissue without injury to critical structures. Therefore, the modality of image guidance has an important impact on the safety and efficacy of percutaneous RF ablation. The current literature regarding percutaneous RF ablation mainly describes the use of computed tomography (CT) and ultrasonography (US) guidance. In addition, interventional MR systems offer the possibility to utilize the advantages of MR imaging such as excellent soft-tissue contrast, multiplanar and interactive capabilities, and sensitivity to thermal effects during the entire RF ablation procedure. Monitoring of thermally induced coagulation by MR imaging is supportive to control the ablation procedure. MR imaging can be advantageously used to guide overlapping ablation if necessary as well as to define the endpoint of RF ablation after complete coverage of the target tissue is verified. Furthermore, monitoring of thermal effects is essential in order to prevent unintended thermal damage from critical structures surrounding the target region. Therefore, MR-guided RF ablation offers the possibility for a safe and effective therapy option in the treatment of primary and secondary hepatic malignancies. The article summarizes the role of MR guidance for RF ablation of liver tumors.