Artificially induced pneumothorax for percutaneous transthoracic radiofrequency ablation of tumors in the hepatic dome: initial experience

After institutional review board approval, informed consent was obtained from six patients (four men and two women, aged 47-74 years) with a total of six tumors of the liver dome. These patients were treated by means of radiofrequency (RF) ablation with computed tomographic (CT) guidance and a transthoracic approach. With use of general anesthesia, a right pneumothorax was induced by means of manual injection of air until the route allowing access to the tumor was cleared of all lung parenchyma. Then RF ablation was performed with transthoracic extrapulmonary transdiaphragmatic access. After retrieval of the RF electrode, the pneumothorax was fully aspirated. All procedures were successfully performed without complications. Artificially induced pneumothorax appears useful and safe for CT-guided RF ablation of liver dome tumors, although this experience was minimal, with only six patients treated.     

Thinking outside the abdominal box: safe use of the epipericardial fat pad window for percutaneous radiofrequency ablation of hepatic dome tumors

Percutaneous imaging-guided tumor ablation is being increasingly performed for local disease control in a variety of primary and secondary neoplasms. Herein, the authors detail their experience with four patients in whom the epipericardial fat pad was traversed to access tumors within the hepatic dome for radiofrequency ablation. The procedure was technically successful in all patients, and the use of this novel window helped avoid crossing the pleura.     

Percutaneous radiofrequency ablation therapy after intrathoracic saline solution infusion for liver tumor in the hepatic dome

Two liver tumors undetected by ultrasonography (US) because they were located in the hepatic dome were treated with radiofrequency (RF) ablation therapy after intrathoracic saline solution infusion. After administration of local anesthesia, artificial pneumothorax was produced by needle thoracentesis and a drainage catheter was inserted into the right thoracic cavity. After saline solution (450-500 mL) was injected into the thoracic cavity via the catheter, US-guided RF ablation was performed. No severe complications occurred and complete therapeutic effects were obtained. Percutaneous RF ablation therapy with intrathoracic saline solution injection seems to be a feasible alternative to other ablation therapies.     

Computed tomography appearances of hypervascular hepatic tumors after percutaneous radiofrequency ablation therapy

A retrospective review of the computed tomography (CT) findings of patients with hypervascular liver tumors (26 hepatocellular carcinomas and 2 metastases [1 periampullary carcinoma and 1 neuroendocrine tumor]) who underwent percutaneous ultrasound-guided radiofrequency ablation (RFA) was performed. CT images consisted of nonenhanced and dual-phase contrast-enhanced helical CT images performed on a multidetector CT scan. Findings indicative of adequate tumor ablation on multidetector CT scanwere complete nonenhancement of the treated tumor with or without faint, thin, peripheral rim enhancement. Ablated lesions that showed complete nonenhancement on initial and subsequent follow-up CT examinations either remained stable or became progressively smaller. Thick rim or nodular peripheral enhancement was indicative of tumor residual or recurrence.     

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.     

Cost-effectiveness of percutaneous radiofrequency ablation for malignant hepatic neoplasms.

PURPOSE: Percutaneous radiofrequency (RF) ablation is a promising technique for the treatment of hepatic malignancies. However, its cost-effectiveness has not been established. The purpose of this study is to determine the cost-effectiveness of RF ablation compared to palliative care in the treatment of hepatocellular cancer and colorectal liver metastases. This study also seeks to evaluate the effects of transition from traditional to newly implemented prospective outpatient reimbursement mechanisms on RF ablation cost-effectiveness. MATERIALS AND METHODS: The marginal direct costs of a percutaneous RF ablation treatment strategy were compared to palliative care over a range of survival benefits with use of a cost-effectiveness model built from the perspective of the payer. Variables used in the model, including complication rates and procedure efficacy, were obtained from the literature and the authors' experience with 46 consecutive patients. RESULTS: The cost-effectiveness of a standardized percutaneous RF ablation treatment strategy compared to palliative care was $20,424, $11,407, $5,034, and $3,492, respectively, per life-year (LY) gained when marginal median survival conferred by RF ablation is 6 months, 1 year, 3 years, and 5 years. The RF ablation treatment strategy would be required to generate 6.14, 2.26, and 1.10 months of marginal median survival benefit to achieve strict ($20,000/LY gained), moderate ($50,000/LY gained), and generous ($100,000/LY gained) cost-effectiveness thresholds. Cost-effectiveness was sensitive to the number of lifetime treatments, hours of observation time, frequency of follow-up evaluations, cost of abdominal computed tomography, and decision to perform RF ablation as an inpatient or outpatient. CONCLUSION: Percutaneous RF ablation is a cost-effective treatment strategy compared to palliative care and has likely already achieved the survival benefit required to meet even a strict cost-effectiveness criterion. Dependence on reimbursement mechanism highlights the importance of concordance between policy and RF ablation technology. The results of this study allow flexible application of cost-effectiveness data despite current uncertainties in treatment and survival data and heterogeneity in treatment populations.     

Society of Interventional Radiology position statement on percutaneous radiofrequency ablation for the treatment of liver tumors

Focal tumor ablation--whether applied percutanously, laparoscopically, or by means of open surgery-is an effective therapy for selected liver tumors. The choice of liver ablation as well as the choice between percutaneous and surgical approaches is dependent on tumor factors, patient factors, and other viable treatment options. Currently, the largest cumulative reported experience is with radiofrequency (RF) ablation of hepatocellular carcinoma and colorectal metastases. This document is a position statement of the Interventional Oncology Task Force and the Standards Division of the Society of Interventional Radiology regarding the use of percutaneous RF ablation for the treatment of liver tumors.     

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.     

CT导向射频消融术治疗肝脏肿瘤

目的:探讨CT导向下经皮肝穿刺射频消融(radiofrequency,RFA)治疗肝脏肿瘤的安全性和有效性。方法:原发和转移性肝脏肿瘤28例,采用Radoionics中空冷却射频仪在CT引导下将射频电极置于肝肿瘤内,同时置入20G的穿刺针,从穿刺针中注入生理盐水5~10ml后进行治疗。并随访6~36个月,运用螺旋CT三期扫描评价治疗效果。结果:28例肝脏肿瘤,病灶32个,原发者20例,转移者8例,肿瘤最大直径≤3cm为26个,肿瘤直径在3~5cm之间为6个,经过RFA治疗,肿瘤完全坏死为25个,部分坏死占7个。6个月生存率100%,12个月生存率71.4%(20/28),生存36个月1例,部分病例还在随访中,未见其他严重并发症。结论:CT导向下经皮肝穿刺射频消融治疗肝脏肿瘤是一种安全、有效的方法。对于肿瘤直径≤3cm的肝脏肿瘤治疗效果较佳。     

Percutaneous radiofrequency ablation of hepatic tumors: postablation syndrome

OBJECTIVE: Our objective was to define the spectrum and possible predictors of symptoms that occur in patients after percutaneous radiofrequency ablation of hepatic tumors. SUBJECTS AND METHODS: We performed 50 consecutive percutaneous radiofrequency ablation sessions on 39 patients with a total of 89 liver tumors. All patients had pre- and postablation laboratory studies and CT or MRI scans. After treatment, patients were followed for 3 weeks with a standardized questionnaire to assess for postablation symptoms. Comparisons of the presence or absence of symptoms were made for the laboratory test values, liver volumes, and pre- and postablation tumor volumes. RESULTS: Postablation symptoms occurred in 14 of 39 (36%) patients after 17 of 50 (34%) ablation sessions. Symptoms consisted of fever (16/17), malaise (12/17), chills (6/17), delayed pain (5/17), and nausea (2/17). On average, the symptoms presented 3 days after ablation and lasted 5 days. Statistically significant (p < 0.01) predictors of symptoms were tumor volumes > 50 cm3 (4.5 cm diameter), ablated tissue volumes > 150 cm3 (6.5 cm diameter), a difference between preablation tumor volume and the volume of tissue ablated > 125 cm3, or postablation aspartate aminotransferase levels > 350 IU/L. CONCLUSION: Approximately one third of patients undergoing percutaneous radiofrequency ablation of hepatic tumors develop delayed, transient flulike symptoms that can be treated conservatively and are significantly related to the volume of tissue ablated. Familiarity with this postablation syndrome should facilitate appropriate management of affected patients.     

Multipolar radiofrequency ablation of hepatic tumors: initial experience

Institutional review board approval and patient informed consent were obtained. Use of a multipolar radiofrequency (RF) ablation device in patients with hepatic malignancy was prospectively evaluated with regard to feasibility, achieved ablation zone size and shape, technical effectiveness, and complications. Nineteen malignant liver tumors were treated with the multipolar resistance-controlled RF ablation system, with which up to three internally cooled bipolar coagulation electrodes can be operated simultaneously. Postinterventional imaging was performed with dynamic contrast material-enhanced magnetic resonance (MR) imaging and MR imaging-based three-dimensional planimetry. Complete tumor destruction was achieved in 18 of 19 tumors. Mean ablation zone volume was 52 mL +/- 45 (standard deviation). Thirteen patients were treated with a percutaneous approach; six, with an intraoperative approach. Maximum ablation size was 91 x 62 x 79 mm with the percutaneous and 73 x 98 x 74 mm with the intraoperative approach. Of the 18 completely evaluable ablation zones, 13 were concentric, two were moderately eccentric, two were eccentric, and one was wedge-shaped. The multipolar RF ablation device achieves large ablation zones and has high technical effectiveness in treating hepatic tumors.     

Needle tract seeding after radiofrequency ablation of hepatic tumors

PURPOSE: To determine the incidence and risk factors associated with needle tract seeding after radiofrequency ablation (RFA) of liver tumors. MATERIALS AND METHODS: A prospective data base of patients with hepatic tumors treated by RFA from December 1999 until August 2003 was reviewed to identify patients with needle tract seeding. During this period, 200 patients (148 men, 52 women) with 299 lesions underwent 298 treatment sessions. Patients with both primary (153 hepatocellular carcinoma, two cholangiocarcinoma) and a variety of secondary tumors (35 colorectal, 10 other) were treated. RFA was performed percutaneously with computed tomography (CT) and/or ultrasound (US) guidance, or with US guidance at laparoscopy or laparotomy. All procedures were performed with a LeVeen needle electrode. The needle tract was not routinely coagulated or embolized. RESULTS: Eight patients out of 200 (4%) were identified with needle tract seeding, based on imaging findings or surgical reintervention. This corresponds to a rate of eight of 298 (2.7%) per treatment session and eight of 299 (2.7%) per lesion. Statistically significant risk factors for neoplastic seeding included treatment of a subcapsular lesion (OR = 11.57, P = .007), multiple treatment sessions (OR = 2.0, P = .037), and multiple electrode placements (OR = 1.4, P = .006). CONCLUSIONS: Neoplastic seeding may occur after RFA of liver tumors. The results show that the frequency of this complication is not insignificant, and are at the upper end of rates reported in the literature of 0.5% to 2.8%. Specific risk factors identified in this study include treatment of subcapsular lesions, patients treated in multiple sessions, and lesions requiring more than one electrode placement.     

Percutaneous radiofrequency ablation for hepatic tumors: factors affecting baseline impedance

PURPOSEWe aimed to evaluate factors that affect baseline impedance of percutaneous radiofrequency ablation.METHODSIn this retrospective study, we analyzed 51 patients with 55 hepatic tumors from November 2015 until April 2018. We measured the baseline impedance nine times with three adjustable tip sizes (2 cm, 2.5 cm, 3 cm) and three different pad locations (two pads attached on the thigh, four on the thigh, two on the back). The first roll-off time was measured with two grounding pads attached on the back. Body mass index, cirrhotic or non-cirrhotic liver parenchyma, previous procedure, tumor location, artificial ascites, active tip size, and the pad location were evaluated as potential factors affecting baseline impedance using the Mann–Whitney U test, t-test and analysis of variance test.RESULTSComplete radiofrequency ablation was achieved in 51 patients. Body mass index (p = 0.897), cirrhotic or non-cirrhotic liver parenchyma (p = 0.767), previous procedure (p = 0.957), tumor location (p = 0.906), and artificial ascites (p = 0.882) did not significantly affect baseline impedance. Grounding pads located on the back showed the lowest baseline impedance (p < 0.001). Increase in active tip size showed gradual decrease in baseline impedance (p = 0.016).CONCLUSIONThe factors affecting baseline impedance were the pad location and the tip size. Positioning pads on the back lowers the baseline impedance and can shorten the first roll-off time, ultimately resulting in reduced total ablation time.

Hepatocellular carcinoma (HCC) continues to be the most prevalent primary liver malignancy and is the third leading cause of cancer-related deaths worldwide (1–3). According to the 2018 European Association for the Study of the Liver clinical practice guidelines (4), ablation is the standard of care for patients with very early stage HCC (Barcelona clinic liver cancer staging system, BCLC-0), and can be adopted as first-line therapy even in surgical patients. Additionally, thermal ablation in single tumors sized 2 to 3 cm is an alternative to surgical resection based on tumor location and patient condition (4). Baseline impedance of radiofrequency ablation (RFA) is measured with a single monopolar electrode before ablation automatically (5). The impedance-controlled mode is generated with an initial set value, which can be adjusted by means of a radiofrequency (RF) output control (5). The first roll-off occurs when the impedance is increased 60% over the initial value (5). Hence, low baseline impedance suggests a short first roll-off time, which is expected to eventually reduce the entire ablation time (6). The aim of this study was to evaluate factors that significantly affect baseline impedance during RFA.     

Right thoracic paravertebral anaesthesia for percutaneous radiofrequency ablation of liver tumours

Objectives

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

Methods

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

Results

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

Conclusion

A right TPVB is safe and effective for anaesthesia and analgesia during PRFA of malignant liver tumours.Percutaneous radiofrequency ablation (PRFA) is currently the mainstay of management, at most centres, for patients with primary and secondary malignant liver tumours [1-3]. Anaesthesia for PRFA of liver tumours usually involves local anaesthesia and intravenous sedation [1,4]. However, intraoperative and early post-operative pain is frequently reported by the majority of patients undergoing such procedures [5-8].Thoracic paravertebral block (TPVB) is the technique of injecting local anaesthetic adjacent to the thoracic vertebra close to where the spinal nerves exit the intervertebral foramina [9]. This produces ipsilateral, segmental, somatic and sympathetic nerve blockade without causing major haemodynamic changes [9]. TPVB is effective in managing liver capsule pain after blunt trauma and for analgesia following radiofrequency ablation of a liver mass [10,11]. It has been used extensively at our centre for chest and upper abdominal surgery, including hepatectomy [12]. However, there are no data on the safety and efficacy of TPVB as the sole anaesthetic technique for PRFA of liver tumours, which this study was designed to investigate.     

经皮射频消融术治疗椎体肿瘤合适消融时间的实验研究

目的 探索经皮射频消融术(RFA)治疗兔椎体肿瘤模型不同消融时间的疗效及安全性.方法 采用CT引导经皮穿刺法将VX2瘤块接种入新西兰大白兔的腰椎内,成功建立20只兔椎体肿瘤模型.将其随机分为A、B两组,每组10只.测量肿瘤椎体的核素标准化摄取值(stand uptake value,SUV),然后对实验动物行消融治疗.A组消融持续时间3 min,B组为5 min,观察治疗后24 h动物急性瘫痪发生情况.治疗后第1天和第7天,实验动物再次接受PET-CT检查,测定椎体肿瘤的SUV值,然后取肿瘤标本行病理检查.比较两组动物RFA术后的瘫痪率以及治疗前后不同时间点的肿瘤SUV值有无差异.结果 A、B两组动物射频后的瘫痪发生率差异有统计学意义(1/10比6/10、P＜0.05).两组肿瘤模型消融前的SUV值分别为4.60±0.47、4.48±0.45,治疗后第1天分别为0.94±0.08、0.92±0.07,治疗后第7天分别为0.93±0.04、0.95±0.06.两组椎体肿瘤的SUV值在治疗前、后差异有统计学意义(F=3 257.87、P＜ 0.05),两组之间则差异无统计学意义.病理结果显示两组肿瘤模型的肿瘤细胞明显坏死,均未见明显残存肿瘤细胞.结论 应用RFA治疗兔椎体肿瘤,消融时间持续3 min已能有效杀伤椎体肿瘤细胞,且严重并发症的概率小.延长消融时间疗效无显著增加,但可能增加神经损伤的风险.