Fangyi Liu

A comparison of microwave ablation and bipolar radiofrequency ablation both with an internally cooled probe: Results in ex vivo and in vivo porcine livers

PURPOSE The purpose of this study was to compare the effectiveness of microwave (MW) ablation and radiofrequency (RF) ablation using a single internally cooled probe in a hepatic porcine model. MATERIALS AND METHODS In the ex vivo experiment, MW ablations (n=40) were performed with a 2450MHz and 915MHz needle antenna, respectively at 60W, 70W power settings. Bipolar RF ablations (n=20) were performed with a 3-cm (T30) and 4-cm (T40) active tip needle electrodes, respectively at a rated power 30W and 40W according to automatically systematic power setting. In the in vivo experiment, the 2450 MHz and 915 MHz MW ablation both at 60W and T30 bipolar RF ablation at 30 W were performed (n=30). All of the application time were 10 min. Long-axis diameter (Dl), short-axis diameter (Ds), ratio of Ds/Dl, the temperature data 5mm from the needle and the time of temperature 5mm from the needle rising to 54°C were measured. RESULTS Both in ex vivo and in vivo models, Ds and Dl of 915 MHz MW ablations were significantly larger than all the RF ablations (P<0.05); the Ds for all the 2450MHz MW ablations were significantly larger than that of T30 RF ablations (P<0.05). 2450MHz MW and T30 RF ablation tended to produce more elliptical-shaped ablation zone. Tissue temperatures 5mm from the needle were considerably higher with MW ablation, meanwhile MW ablation achieved significantly faster rate of temperature rising to 54°C than RF ablation. For in vivo study after 10 min of ablation, the Ds and Dl of 2450 MHz MW, 915 MHz MW and Bipolar RF were 2.35±0.75, 2.95±0.32, 1.61±0.33 and 3.86±0.81, 5.79±1.03, 3.21±0.51, respectively. Highest tissue temperatures 5mm from the needle were 80.07±12.82°C, 89.07±3.52°C and 65.56±15.31°C and the time of temperature rising to 54°C were respectively 37.50±7.62s, 24.50±4.09s and 57.29±23.24s for three applicators. CONCLUSION MW ablation may have higher potential for complete destruction of liver tumors than RF ablation.

Ultrasound-guided percutaneous microwave ablation of benign thyroid nodules: experimental and clinical studies

PURPOSE To obtain the treatment parameters of internally cooled microwave antenna and to evaluate the feasibility of ultrasound-guided percutaneous microwave ablation (MWA) for benign thyroid nodules. MATERIALS AND METHODS MWAs were performed by microwave antenna (16G) in ex vivo porcine liver. The lesion diameters achieved in different groups (20, 25, and 30 W for 3, 5, 7, 10, and 12 min) were compared. The clinical study was approved by the ethics committee. Written informed consent was obtained from all patients. MWA was performed in 11 patients (male to female ratio=1:10; mean age, 50±7 years) with 11 benign thyroid nodules. Ultrasound scan, laboratory data, and clinical symptoms were evaluated before and 1 day and 1, 3, 6, 9, and 12 months after the procedure. RESULTS In ex vivo study, the ablation lesion at 30 W 12 min tended to have appropriate scope and spherical shape. In clinical study, the follow-up periods ranged from 1 to 9 months. At the last follow-up, the largest diameter decreased from 2.9±1.0 (range, 1.6-4.1) to 1.9±0.7 (range, 0.4-3.0) cm (P<0.01), and the volume decreased from 5.30±4.88 (range, 0.89-14.81) to 2.40±2.06 (range, 0.02-6.35) ml (P<0.01). The volume reduction ratio was 45.99±29.90 (range, 10.56-98.15) %. The cosmetic grading score was reduced from 3.20±0.79 to 2.30±0.95 (P<0.05). One patient experienced temporary nerve palsy and was recovered within 2 months after treatment. CONCLUSION The internally cooled microwave antenna can yield ideal ablation lesions, and ultrasound-guided percutaneous MWA is a feasible technique for benign thyroid nodules.

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.

Comparison of percutaneous 915 MHz microwave ablation and 2450 MHz microwave ablation in large hepatocellular carcinoma

Purpose: To compare the effectiveness of ultrasound (US)-guided percutaneous 915 MHz microwave (MW) ablation with the 2450 MHz MW ablation for large hepatocellular carcinoma (HCC) (>4 cm in diameter). Materials and methods: Patients with HCC >4 cm in diameter who underwent US-guided percutaneous MW ablation with curative intention between March 2007 and December 2008 (39) were randomly divided into two groups, 915 MHz MW group and 2450 MHz MW group. We compared the results of ablation between the two groups. Results: Fewer antenna insertions for each tumour were required in the 915 MHz MW group (3.69 ± 0.6) than in the 2450 MHz MW group (4.71 ± 1.61) (p = 0.01). According to the follow-up contrast-enhanced imagings, technique effectiveness rate was 85.7% (18/21) and 73.7% (14/19) in the 915 MHz MW group and 2450 MHz MW group, respectively (p = 0.44). The rate of local tumour progression (LTP) was 14.3% (3/21) and 26.3% (5/19) in the 915 MHz MW group and 2450 MHz MW group, respectively (p = 0.44). There were no deaths and no thrombosis of major vessels in any patient. Conclusions: Compared with 2450 MHz MW ablation, our initial experience showed that percutaneous 915 MHz MW ablation with cooled-shaft antennae was safe and could achieve a high technique effectiveness rate with fewer insertion numbers in the treatment of large HCC. Therefore, percutaneous 915 MHz MW ablation may provide a new method for the treatment of large HCC.

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.

MWA Combined with TACE as a combined therapy for unresectable large-sized hepotocellular carcinoma

Purpose: To evaluate the efficacy and safety of microwave ablation combined with transcatheter arterial chemoembolization for unresectable large-sized hepotocellular carcinoma. Materials and methods: Institutional review board approval and informed consent were obtained. Between May 2004 and December 2006, 34 consecutive patients with large unresectable hepatocellular carcinoma (>5 cm) were alternately enrolled in one of two treatment groups: group 1 (n = 18), in which TACE was performed alone, and group 2 (n = 16), in which percutaneous ablation of HCC with microwave ablation was performed 2–4 weeks after TACE. All patients were followed up for 2–28 months to observe long-term therapeutic effects and complications in both groups. Tumor reduction rates, median survival time, and cumulative survival rates in both groups were calculated by using the unpaired Student t test and Kaplan-Meier method. Results: Follow-up images showed reduction in tumor size was seen in 21 patients (61.7%; 7/18 in group 1, 14/16 in group 2), survival rates were better in group 2 than in group 1 (P = 0.003), during the median follow-up of 8 months, 10 patients (62.5%) remained alive in group 2, whereas 6 patients (33.3%) remained alive in group 1, the mean survival times were 6.13 months ± 0.83 in group 1 and 11.61 months ± 1.59 in group 2. Conclusion: MWA combined with transcatheter arterial chemoembolization appears to be an effective and promising approach for the treatment of large-sized unresectable hepotocellular carcinoma. However, large-scale randomized clinical trials are needed to determine the future role of this treatment.

A three-dimensional visualisation preoperative treatment planning system in microwave ablation for liver cancer: A preliminary clinical application

Abstract Objectives: The aim of this study was to evaluate the clinical application value of a 3D visualisation preoperative treatment planning system in microwave ablation for liver cancer. Methods: From December 2011 to November 2012, 94 enrolment patients of liver cancer were divided into two groups. The 3D preoperative planning group included 36 patients with 44 lesions, who underwent microwave ablation with the aid of the self-developed 3D visualisation preoperative treatment planning system. The 2D preoperative planning group included 58 patients with 64 lesions, who underwent microwave ablation according to conventional 2D image preoperative planning methods. After microwave ablation, therapeutic efficacy was assessed by contrast-enhanced imaging during follow-up. Results: The 3D preoperative planning group had a higher success rate of first ablation than the 2D preoperative planning group (p = 0.01). There were more sessions in the 2D preoperative planning group than in the 3D preoperative planning group (p = 0.002). There were no significant differences in technique effectiveness rate between the 2D preoperative planning group (96.55%) and the 3D preoperative planning group (100%) according to the contrast-enhanced imaging follow-up after microwave ablation (p = 0.64). There were no significant differences in the rate of LTP between the 2D preoperative planning group and the 3D preoperative planning group (p = 0.64) during 3–12 months follow up (median 6 months). Conclusions: Compared with the 2D preoperative planning group, the 3D preoperative planning group had a higher success rate of first ablation and fewer sessions. Therefore, the 3D visualisation preoperative treatment planning system has a relatively high clinical application value.

Real-time contrast-enhanced ultrasound in diagnosing of focal spleen lesions

OBJECTIVE To investigate the features of focal spleen lesions (FSLs) on contrast-enhanced ultrasound (CEUS) imaging. MATERIALS AND METHODS CEUS with a blot injection of SonoVue was performed in 48 patients with 75 FSLs (median diameter 2.6cm) and their perfusion characteristics were analyzed by using contrast pulse sequences (CPS) technique. RESULTS Among 19 malignant lesions (10 metastases, 7 lymphoma, 1 hemangiosarcoma, 1 epithelioid hemangioendothelioma) and 56 benign lesion (23 hemangiomas, 14 cysts, 8 infarctions, 4 splenic ruptures, 3 tuberculosis, 2 abscess, 1 pseudoaneurysm, 1 lymphangioma), 25 benign lesions were demonstrated nonenhancement. For malignancy, 50.0% (5/10) metastases and 57.1% (4/7) lymphomas were showed hypoenhancement in the arterial phase, and 18 (94.7%) of malignant lesions were hypo-enhancement in the parenchymal phase. Among 31 benign lesions with enhancement, 27 (87.1%) were showed isoenhancement or hyperenhancement in the arterial phase and 22 (71.0%) lesions were isoenhancement or hyperenhancement in the parenchymal phase. The sensitivity, specificity and accuracy of diagnosis for FSLs were 91.1%, 95.0% and 92.0% for CEUS and 75.0%, 84.2% and 77.3% respectively, for the conventional baseline ultrasound (BUS). CONCLUSION Real-time CEUS can provide valuable information for the diagnosis and differential diagnosis of FSLs.

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.

Safety assessment and therapeutic efficacy of percutaneous microwave ablation therapy combined with percutaneous ethanol injection for hepatocellular carcinoma adjacent to the gallbladder

Abstract Objective: This study sought to evaluate the safety and efficacy of ultrasound-guided (US-guided) percutaneous microwave (MW) ablation combined with percutaneous ethanol injection (PEI) to treat liver tumours adjacent to the gallbladder. Materials and methods: A total of 136 patients with hepatocellular carcinoma (HCC) adjacent to the gallbladder, who underwent ultra-sonographically-guided percutaneous MW ablation, which was combined with PEI in132 patients, were retrospectively assessed. The patient population characteristics, tumour features, local tumour progression and treatment were compared and analysed. The safety and efficacy of the therapy were assessed by clinical data and imaging in follow-up examinations. Results: All patients were completely treated with two sessions; 120 patients underwent one session, 16 patients underwent two sessions. The primary technique was effective in 95.6% of the cases, according to the computed tomography (CT) or magnetic resonance imaging (MRI) in the one-month follow-up (132 of 138 sessions). PEI and other therapies were performed in the patients who had been incompletely treated (all six patients underwent PEI, and some underwent other therapies, including one transcatheter arterial chemoembolisation (TACE), one liver transplantation and two liver resections). There was a median follow-up period of 30.1 months and a range of 4 to 68 months. None of the patients had major complications. There were no treatment-related deaths. Twenty-six patients died of primary disease progression that was not directly attributable to MW ablation (19.1%, 26/136). Local tumour progression was noted in five patients (3.7%, 5/136), who had completely ablated tumours at follow-up. The patients with locally progressing tumours underwent additional therapy (three patients underwent PEI, one patient TACE, and one liver resection). Conclusion: Ultrasound-guided percutaneous MW ablation, in combination with percutaneous ethanol injection and thermal monitoring, is a safe and effective treatment for HCC adjacent to the gallbladder.