Baowei Dong

Malignant Liver Tumors: Treatment with Percutaneous Microwave Ablation―Complications among Cohort of 1136 Patients

PURPOSE To report the complications for percutaneous microwave (MW) ablation for the treatment of malignant liver tumors and the possible risk factors for complications in a large series of patients. MATERIALS AND METHODS The study was approved by the institutional review board; informed consent was waived because of the retrospective design. Over a 13-year period, 1136 patients with 1928 malignant liver tumors underwent ultrasonographically guided percutaneous MW ablation (583 with a noncooled-shaft antenna and 553 with a cooled-shaft antenna). A total of 3697 MW ablation sessions (average, 1.8 sessions per patient) were performed. Mortality and treatment-related major and minor complications were documented. Data were subsequently analyzed to determine whether the major complication rate was related to antenna type, tumor size, tumor location, or number of MW sessions. RESULTS Two deaths not directly attributable to MW ablation were encountered. Major complications occurred in 30 (2.6%) patients and included liver abscess and empyema (n = 5), bile duct injury (n = 2), perforation of the colon (n = 2), tumor seeding (n = 5), pleural effusion requiring thoracentesis (n = 12), hemorrhage requiring arterial embolization (n = 1), and skin burn requiring resection (n = 3). Minor complications included fever; pain; asymptomatic pleural effusion, gallbladder wall thickening, and arterioportal shunt; small stricture of the bile duct; and skin burn requiring no treatment. Use of noncooled-shaft antenna and an increased number of MW ablation sessions were associated with a higher rate of major complications (P < .05). CONCLUSION MW ablation is a well-tolerated technique with an acceptably low rate of major complications for treatment of malignant liver tumors. Use of a cooled-shaft antenna, as well as fewer MW sessions, may help minimize major complications.

Computer-aided dynamic simulation of microwave-induced thermal distribution in coagulation of liver cancer

To develop a method of dynamic three-dimensional (3-D) simulation of thermal distribution in ultrasound-guided microwave coagulation therapy of liver cancer and to verify its accuracy. The specific absorption rate (SAR) values were established by measuring the temperature in equivalent phantom tests. Those values were different under different power output condition. Dynamic 3-D temperature distributions were reconstructed with a finite-element model. Testing and rectification were performed through animal experiments and clinical trials, respectively. The temperature curves in the experiments corresponded well with simulated ones in vitro--91.4% and 88.9% using single and double electrodes, respectively. The measured coagulated boundary and simulated temperature boundary had a good correspondence in 85.7% of the specimens. In both in vivo experiments and clinical trials, blood perfusion influenced the rise in temperature significantly. Temperature curves between the simulations and actual measured results showed good correspondence--67.8% (19/28) in the patients with hepatocellular carcinoma. Distance between electrodes and combined thermal distributions were both optimized with computer-aided simulation during simultaneous two-electrode coagulation. The results demonstrated that computer-aided simulation of microwave thermal distribution is an accurate and reliable method which provides a theoretical and technical basis for controlling coagulated tissue volume and placement of the electrodes during microwave coagulation therapy of liver cancer.

Microwave ablation assisted by a real-time virtual navigation system for hepatocellular carcinoma undetectable by conventional ultrasonography

OBJECTIVES To evaluate the efficiency and feasibility of microwave (MW) ablation assisted by a real-time virtual navigation system for hepatocellular carcinoma (HCC) undetectable by conventional ultrasonography. METHODS 18 patients with 18 HCC nodules (undetectable on conventional US but detectable by intravenous contrast-enhanced CT or MRI) were enrolled in this study. Before MW ablation, US images and MRI or CT images were synchronized using the internal markers at the best timing of the inspiration. Thereafter, MW ablation was performed under real-time virtual navigation system guidance. Therapeutic efficacy was assessed by the result of contrast-enhanced imagings after the treatment. RESULTS The target HCC nodules could be detected with fusion images in all patients. The time required for image fusion was 8-30 min (mean, 13.3 ± 5.7 min). 17 nodules were successfully ablated according to the contrast enhanced imagings 1 month after ablation. The technique effectiveness rate was 94.44% (17/18). The follow-up time was 3-12 months (median, 6 months) in our study. No severe complications occurred. No local recurrence was observed in any patients. CONCLUSIONS MW ablation assisted by a real-time virtual navigation system is a feasible and efficient treatment of patients with HCC undetectable by conventional ultrasonography.

Phase I clinical study of combination therapy with microwave ablation and cellular immunotherapy in hepatocellular carcinoma

Background and Aims: To observe safety and influence on viral load and peripheral T lymphocyte subsets of combination therapy with percutaneous microwave ablation (PMWA) and adoptive immunotherapy in hepatocellular carcinoma (HCC) with hepatitis B. Methods: Ten HCC （D≤5 cm, fewer than 3 tumors） patients were treated with radical PMWA and three courses of immunotherapy, which were started with PMWA, 2 weeks post-PMWA, and 3 months after PMWA. Peripheral blood mononuclear cells were differentiated into phenotypically confirmed DCs and effector cells. Immature DCs, cytokine-induced killer cells (CIK) and cytotoxic T lymphocytes (CTL) were injected into the marginal area of ablated tumors under contrast-enhanced sonographic guidance. Under sonographic guidance, tumor lysate-pulsed DC was injected into groin lymph nodes, while DC-CIK and CTL were injected into the abdominal cavity. CIK was infused intravenously. Results: No adverse effects of grade Ⅲ/Ⅳ were observed. Viral load was decreased in 57.14% (four of seven) of patients and was undetectable in two (28.6%) patients without antiviral therapy. The percentage of CD4+CD25high regulatory T lymphocytes decreased significantly, and the percentage of CD8+CD28- effector cells increased significantly 1 month after therapy. However, 6 months after therapy, there was no significant difference. Conclusion: Adoptive immunotherapy prescribed soon after PMWA for HCC patients was safe and ameliorated the percentage of peripheral lymphocytes. See commentary: New prospects for hepatocellular carcinoma therapy: Microwave ablation working together with cellular immunotherapy

Sequential pathological and immunologic analysis of percutaneous microwave coagulation therapy of hepatocellular carcinoma.

Purpose: To evaluate sequential pathologic and immunologic changes and their prognostic significance after percutaneous microwave coagulation therapy (PMCT) of hepatocellular carcinoma (HCC). Methods: Eighty-nine nodules in 82 consecutive patients were studied. The 89 nodules were divided into two groups: a treatment group, with 82 primary nodules (average dimension was 3.4 - 1.2 cm) in 82 patients, and a control group, of seven nodules (average dimension was 1.4 - 0.6 cm) in seven patients. The criteria for a nodules inclusion in the control group was that the nodule was one of two nodules in the same patient and that the two nodules were located in different liver lobes. This guarantees that while one nodule is treated by PMCT, the distant one will not be directly affected by the microwave thermal field. The control group nodules were treated after the study was completed. Specimens were taken with ultrasound-guided liver biopsy from the treated nodule and the control nodule, pre- and post-PMCT. Infiltration by T-lymphocytes, B-lymphocytes, NK cells and macrophages in the tumour tissue were observed immunohistochemically using a panel of monoclonal antibodies against CD3, CD45RO, CD20, CD56 and CD68. The extent of immune cell infiltration was compared both before and after PMCT, as well as between the treated and control nodules. The relationship between the prognosis and the extent of immunocyte infiltration was analysed. Results: The patients were followed for 2-26 months (mean 14.6 - 6.3) post-treatment. The recurrence rates at 1 and 2 years were 20.4% and 28.1% within the liver in treatment group, respectively. The survival rates at 1 and 2 years were 92.5% and 75.3% for the treatment group. T-cells, NK cells and macrophages increased significantly in both treated and untreated nodules after PMCT, albeit less markedly within untreated nodules when compared to the treated ones. There is a statistically significant correlation between survival outcome and the extent of immunocyte infiltration. Conclusions: For inoperable HCC patients, PMCT is one of the treatment choices shown to be effective. Apart from its tissue coagulation effect, an increased systemic immune response directed against the tumour may also play an important role in improved survival.

Practice guidelines for ultrasound-guided percutaneous microwave ablation for hepatic malignancy

Primary liver cancer and liver metastases are among the most frequent malignancies worldwide, with an increasing number of new cases and deaths every year. Traditional surgery is only suitable for a limited proportion of patients and imaging-guided percutaneous thermal ablation has achieved optimistic results for management of hepatic malignancy. This synopsis outlines the first clinical practice guidelines for ultrasound-guided percutaneous microwave ablation therapy for hepatic malignancy, which was created by a joint task force of the Society of Chinese Interventional Ultrasound. The guidelines aim at standardizing the microwave ablation procedure and therapeutic efficacy assessment, as well as proposing the criteria for the treatment candidates.

Contrast-enhanced ultrasound-guided microwave ablation for hepatocellular carcinoma inconspicuous on conventional ultrasound

Objective: To evaluate the efficiency and feasibility of contrast-enhanced ultrasound (CEUS)-guided microwave ablation for hepatocellular carcinoma inconspicuous on conventional US. Materials and methods: From March 2006 to February 2010, 107 patients (93 male, 14 female; mean age 58.9 ± 11.0 years) with 107 hepatocellular carcinoma (HCC) nodules (mean maximum diameter 19.5 ± 8.5 mm) inconspicuous on conventional US underwent microwave (MW) ablation under CEUS guidance in this study. US contrast agent was SonoVue (Bracco, Milan, Italy), a second-generation contrast agent. CEUS was performed first, and then MW ablation was carried out by means of CEUS guidance under unconscious intravenous anaesthesia if the tumours were displayed on CEUS. Results: 105 tumours were successfully visualised on CEUS by using 1–2 times contrast agent injection and MW ablation was performed under CEUS guidance. The technical success rate was 98.13% (105/107). The number of antenna insertions for each tumour was 1.89 ± 0.92, and the mean session of MW ablation for each tumour was 1.08 ± 0.28. The mean duration of energy application for each tumour was 7.05 ± 4.03 min. The follow-up time was 12–54 months (median 18 months). The technique effectiveness rate was 99.05% (104/105). The local tumour progression rate was 1.9% (2/105). There were no severe complications in any patients. Conclusion: CEUS-guided MW ablation is an efficient and feasible treatment method for patients with hepatocellular carcinoma inconspicuous on conventional US.

Percutaneous microwave ablation for liver cancer adjacent to the diaphragm

Purpose: The aim of the study was to prospectively evaluate the safety and effectiveness of percutaneous microwave (MW) ablation for liver cancer adjacent to the diaphragm. Materials and methods: From May 2005 to June 2008, 89 patients with 96 hepatic lesions adjacent to the diaphragm (the shortest distance from the lesion margin to the diaphragm less than 5 mm), who underwent ultrasound (US)-guided percutaneous MW ablation, were included in the study group. A total of 100 patients with 127 hepatic lesions not adjacent to the diaphragm (the shortest distance from the lesion to the diaphragm and the first or second branch of the hepatic vessels more than 10 mm), who underwent US-guided percutaneous MW ablation, were included in the control group. During the ablation the temperature of marginal ablation tissue proximal to the diaphragm was monitored and controlled at 50°–60°C for more than 10 min in the study group. We compared the results of ablation between the two groups. Results: A total of 91 of 96 tumours (94.8%) in the study group and 123 of 127 tumours (96.9%) in the control group achieved complete ablation (P > 0.05). Local tumour progression was found in 18 of 96 tumours (18.8%) in the study group and 21 of 127 tumours (16.5%) in the control group during follow-up after MW ablation (P > 0.05). No major complications occurred in either group. Conclusions: Under strict temperature monitoring, percutaneous MW ablation is safe and can achieve a high complete ablation rate for the treatment of hepatic tumours adjacent to the diaphragm.

Microwave ablation: results with double 915 MHz antennae in ex vivo bovine livers.

PURPOSE To investigate the settings for the optimal microwave ablation geometry with the simultaneous application of double 915 MHz antennae in ex vivo bovine livers, so as to provide the technical basis for treating large liver tumor in one ablation session. MATERIALS AND METHODS MWAs were performed on ex vivo bovine livers by simultaneously application of double 915 MHz internally cooled-shaft antennae. Four power settings (50, 60, 70 and 80 W) were used during MWAs, while application time was fixed at 10 min. Three inter-antenna distances (2.0, 2.5 and 3.0 cm) were used. Diameters and shapes of the coagulation zones were observed on gross specimens. RESULTS (1) The coagulation shape was related to the inter-antenna distance, which was most spherical at an inter-antenna distance of 2.0 cm. A recess of the coagulation zone was observed at an inter-antenna distances of 2.5 and 3.0 cm. (2) The long-axis and short-axis coagulation diameter enlarged with increasing power output. However, there were no significant differences in the coagulation diameters between 70 and 80 W (P>0.05). More desirable coagulation geometry could be obtained by simultaneous application of double antennae at 70 W for 10 min with an inter-antenna distance of 2.0 cm, the long-axis and short-axis coagulation diameter were 6.95 ± 0.32 cm and 5.30 ± 0.22 cm, respectively. CONCLUSION Simultaneous application of double 915 MHz antennae can generate large coagulation zones with desirable shape which may be advantageous for treating large liver tumor in one ablation session.

Percutaneous Microwave Ablation or Nephrectomy for VX-2 Carcinoma in Rabbit Kidney

PURPOSE We compared the effectiveness of percutaneous microwave ablation and radical nephrectomy for implanted VX-2 carcinoma in rabbit kidneys. MATERIALS AND METHODS VX-2 tumors were surgically implanted into the left lower pole parenchyma of 26 New Zealand White rabbit kidneys. At 12 days after implantation implanted rabbits were randomly assigned to 1 of 3 groups according to therapy type, including percutaneous microwave ablation, nephrectomy and no treatment. The anticancer effect and safety were compared among the groups. Histopathological changes in tumor tissue with time after microwave ablation were evaluated. RESULTS The survival rate in the percutaneous microwave ablation group was significantly higher than that in the no treatment group and showed no statistically significant difference compared with that in the nephrectomy group. Serum creatinine did not increase after microwave therapy but we noted a statistically significant serum creatinine increase in the nephrectomy group. Histological analysis revealed completely coagulative necrosis of the tumor in 10 of 12 rabbits (83.3%) after microwave ablation. Two rabbits died, including 1 of peritonitis in the nephrectomy group and 1 of intestinal fistula due to heat injury in the percutaneous microwave ablation group. CONCLUSIONS This study shows that percutaneous microwave ablation can achieve effects similar to those of radical nephrectomy. It caused no significant changes in renal function when treating implanted VX-2 renal tumors. Percutaneous microwave ablation has the potential of being a minimally invasive treatment for small renal tumors.