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

Role of Radiotherapy in the Treatment of Hepatocellular Carcinoma

The role of radiotherapy in the treatment of hepatocellular carcinoma (HCC) has evolved over the past few decades with the advancement of technology and improved imaging. Radiotherapy can offer high local control rates in unresectable HCC, including cases with major vascular involvement, and can provide a modality to help bridge patients to potentially curative resection or transplantation. In metastatic cases, radiotherapy can provide good palliation. This review focuses on the common radiotherapy treatment modalities used for HCC, provides outcome comparisons of these radiotherapy techniques to outcomes with other treatment modalities for HCC, and highlights the discrepancy of the role of radiotherapy in HCC amongst the current available treatment guidelines.

Propofol Compared to Midazolam Sedation and to General Anesthesia for Percutaneous Microwave Ablation in Patients with Hepatic Malignancies: A Single-Center Comparative Analysis of Three Historical Cohorts

Purpose

In percutaneous ablation procedures, periprocedural pain, unrest and respiratory concerns can be detrimental to achieve a safe and efficacious ablation and impair treatment outcome. This study aimed to compare the association between anesthetic technique and local disease control in patients undergoing percutaneous microwave ablation (MWA) of colorectal liver metastases (CRLM) and hepatocellular carcinoma (HCC).

Materials and Methods

This IRB-exempted single-center comparative, retrospective analysis of three cohorts analyzed 90 patients treated for hepatic malignancies from January 2013 until September 2018. The local tumor progression-free survival (LTPFS), safety and periprocedural pain perception were assessed using univariate and multivariate Cox proportional hazard regression analyses to correct for potential confounders.

Results

In 114 procedures (22 general anesthesia; 32 midazolam; 60 propofol), 171 liver tumors (136 CRLM; 35 HCC) were treated with percutaneous MWA. Propofol and general anesthesia were superior to midazolam/fentanyl sedation regarding LTPFS (4/94 [4.3%] vs. 19/42 [45.2%] vs. 2/35 [5.7%]; P < 0.001, respectively). Local tumor progression rate was 14.6% (25/171). Eighteen tumors (72.0%) were retreated by ablation. Of them, 14 (78%) were previously treated with midazolam. Propofol versus midazolam (P < 0.001), general anesthesia versus midazolam (P = 0.016), direct postprocedural visual analog pain score above 5 (P = 0.050) and more than one tumor per procedure (P = 0.045) were predictors for LTPFS. Multivariate analysis revealed that propofol versus midazolam (HR 7.94 [95% CI 0.04–0.39; P < 0.001]) and general anesthesia versus midazolam (HR 6.33 [95% CI 0.04–0.69; P = 0.014]) were associated with LTPFS. Pain during and directly after treatment was significantly worse in patients who received midazolam sedation (P < 0.001).

Conclusions

Compared to propofol and general anesthesia, midazolam/fentanyl sedation was associated with an increased periprocedural perception of pain and lower local tumor progression-free survival. To reduce the number of repeat procedures required to eradicate hepatic malignancies, general anesthesia and propofol sedation should be favored over midazolam.

Radiofrequency Ablation and Microwave Ablation in Liver Tumors: An Update

This article provides an overview of radiofrequency ablation (RFA) and microwave ablation (MWA) for treatment of primary liver tumors and hepatic metastasis. Only studies reporting RFA and MWA safety and efficacy on liver were retained. We found 40 clinical studies that satisfied the inclusion criteria. RFA has become an established treatment modality because of its efficacy, reproducibility, low complication rates, and availability. MWA has several advantages over RFA, which may make it more attractive to treat hepatic tumors. According to the literature, the overall survival, local recurrence, complication rates, disease-free survival, and mortality in patients with hepatocellular carcinoma (HCC) treated with RFA vary between 53.2 ± 3.0 months and 66 months, between 59.8% and 63.1%, between 2% and 10.5%, between 22.0 ± 2.6 months and 39 months, and between 0% and 1.2%, respectively. According to the literature, overall survival, local recurrence, complication rates, disease-free survival, and mortality in patients with HCC treated with MWA (compared with RFA) vary between 22 months for focal lesion >3 cm (vs. 21 months) and 50 months for focal lesion ≤3 cm (vs. 27 months), between 5% (vs. 46.6%) and 17.8% (vs. 18.2%), between 2.2% (vs. 0%) and 61.5% (vs. 45.4%), between 14 months (vs. 10.5 months) and 22 months (vs. no data reported), and between 0% (vs. 0%) and 15% (vs. 36%), respectively. According to the literature, the overall survival, local recurrence, complication rates, and mortality in liver metastases patients treated with RFA (vs. MWA) are not statistically different for both the survival times from primary tumor diagnosis and survival times from ablation, between 10% (vs. 6%) and 35.7% (vs. 39.6), between 1.1% (vs. 3.1%) and 24% (vs. 27%), and between 0% (vs. 0%) and 2% (vs. 0.3%). MWA should be considered the technique of choice in selected patients, when the tumor is ≥3 cm in diameter or is close to large vessels, independent of its size. IMPLICATIONS FOR PRACTICE: Although technical features of the radiofrequency ablation (RFA) and microwave ablation (MWA) are similar, the differences arise from the physical phenomenon used to generate heat. RFA has become an established treatment modality because of its efficacy, reproducibility, low complication rates, and availability. MWA has several advantages over RFA, which may make it more attractive than RFA to treat hepatic tumors. The benefits of MWA are an improved convection profile, higher constant intratumoral temperatures, faster ablation times, and the ability to use multiple probes to treat multiple lesions simultaneously. MWA should be considered the technique of choice when the tumor is ≥3 cm in diameter or is close to large vessels, independent of its size.

Comparison of parallel and crossed placement of antennas in microwave ablation of 3-5 cm hepatocellular carcinoma

PURPOSE

To evaluate the effects of ablation strategies on local tumor progression (LTP) after microwave ablation (MWA) of hepatocellular carcinomas (HCCs) measuring 3-5 cm.

MATERIALS AND METHODS

Between December 2011 and May 2017, 71 HCC patients with 71 nodules treated by ultrasound(US)-guided percutaneous MWA were divided into parallel (group A) and crossed (group B) antenna placement groups. All patients underwent MWA using two antennas with four insertions. LTP and overall survival (OS) rates were compared between the two groups.

RESULTS

The median follow-up time was 16.8 months. There was no significant difference in the complete ablation rate and treatment sessions between the two groups. LTP was diagnosed in 8 of 48 nodules (16.7%) in group A and 1 of 23 nodules (4.3%) in group B, with no significant difference between two groups (P = 0.115). The 1-, 2-, and 3-year OS rates were 88.5%, 79%, and 71.8% in group A and 93.8%, 87.5%, and 87.5% in group B, respectively (P = 0.236). Multivariate analysis showed that the tumor diameter (P = 0.017), the distance between the antennas (P = 0.032), and the total emission time (P = 0.015) were associated with LTP.

CONCLUSIONS

There were trends with lower LTP and improved OS in group B, despite the lack of statistically significant differences between the two strategies at a level of P < 0.05. The increase of distance between antennas and total emission time will facilitate reductions in LTP rate.

Development of a Model for Training and Assessing Open Image-Guided Liver Tumor Ablation

BACKGROUND

Image-guided microwave ablation (MWA) is a technically demanding procedure, involving advanced visual-spatial perception skills. This study sought to create and evaluate a low-cost model and training curriculum for open ultrasound-guided liver tumor MWA.

METHODS

Simulated tumors were created, implanted into bovine livers, and visualized by ultrasound. A high-fidelity abdominal model was constructed, with a total cost of $30. Experienced physicians in MWA performed simulated ablations and evaluated the model. Expert performance metrics were established and served as targets for our training curriculum. These included time, number of passes, number of repositionings, and percentage of tumor ablated. Next, 8 novice trainees completed our deliberate practice curriculum. Participants' performances were recorded throughout.

RESULTS

Physicians completed a structured feedback questionnaire rating the model's realism and training utility at 8/10 and 10/10, respectively. Tumors appeared hyperechoic and were clearly visualized on ultrasound. Trainees performed a total of 32 ablations. Our trainees' performance improved significantly in all outcomes of interest in the postcurriculum ablations compared to precurriculum ablations.

CONCLUSION

We have created a cost-effective, high-fidelity model of MWA, with a deliberate practice curriculum. Trainees can practice to proficiency with clear target metrics prior to participating in clinical cas.

Monitoring Microwave Ablation Using Ultrasound Echo Decorrelation Imaging: An ex vivo Study

In this study, a microwave-induced ablation zone (thermal lesion) monitoring method based on ultrasound echo decorrelation imaging was proposed. A total of 15 cases of ex vivo porcine liver microwave ablation (MWA) experiments were carried out. Ultrasound radiofrequency (RF) signals at different times during MWA were acquired using a commercial clinical ultrasound scanner with a 7.5-MHz linear-array transducer. Instantaneous and cumulative echo decorrelation images of two adjacent frames of RF data were calculated. Polynomial approximation images were obtained on the basis of the thresholded cumulative echo decorrelation images. Experimental results showed that the instantaneous echo decorrelation images outperformed conventional B-mode images in monitoring microwave-induced thermal lesions. Using gross pathology measurements as the reference standard, the estimation of thermal lesions using the polynomial approximation images yielded an average accuracy of 88.60%. We concluded that instantaneous ultrasound echo decorrelation imaging is capable of monitoring the change of thermal lesions during MWA, and cumulative ultrasound echo decorrelation imaging and polynomial approximation imaging are feasible for quantitatively depicting thermal lesions.

A tumor map generated from three-dimensional visualization of image fusion for the assessment of microwave ablation of hepatocellular carcinoma: a preliminary study

PURPOSE

This study aimed to investigate the clinical value of a tumor map for assessing the ablative effect after ultrasound-guided percutaneous microwave ablation (US-PMWA) for hepatocellular carcinoma (HCC).

METHODS

The medical records of 68 patients (49 male and 19 female, 59.9±12.7 years) with HCC who underwent US-PMWA from May 2013 to May 2017 were reviewed. A tumor map was generated from the fusion of three-dimensional (3D) visualization images based on the preoperative target tumor and postoperative ablation area, to evaluate whether the ablation area covering the tumor has reached a 5 mm ablative margin (AM). The lesions were divided into two groups according to the tumor maps: group A (failed to achieve AM) and group B (achieved AM). The cumulative local tumor progression (LTP) rates of both groups were statistically analyzed using the log-rank test.

RESULTS

Success rate of tumor map generation was 100% (68/68), and no residual tumors were found. MWA-related 3D images, which included target tumor volume, ablation area volume, and residual liver ratio, were compared between groups A and B (P=0.295, P=0.772, and P=0.527, respectively). Technique effectiveness rate (91.7% vs 100%) was achieved in the two groups, showing no significant statistical differences (P=0.672). The 3-, 6-, 9-, and 12-month LTP rate was 8.3%, 16.7%, 20.8%, and 34%, respectively, for group A and 0%, 2.8%, 2.8%, and 2.8%, respectively, for group B, showing significant statistical differences (P<0.001) between the two groups.

CONCLUSION

The novel technology of tumor map generated from 3D visualization of image fusion is feasible and useful in evaluating the ablative effect of US-PMWA for HCC.

Ultrasound-guided percutaneous microwave ablation assisted by athree-dimensional visualization treatment platform combined with transcatheter arterial chemoembolization for a single large hepatocellular carcinoma 5 cm or larger: a preliminary clinical application

Objective: To assess the clinical efficiency and feasibility of ultrasound-guided percutaneous microwave ablation (US-PMWA) assisted by a three-dimensional (3D) visualization platform for treating a single large hepatocellular carcinoma (HCC) (diameter ≥5 cm).Methods: We included 40 patients with a single large HCC from May 2015 to August 2017. Nineteen patients who underwent US-PMWA assisted by a 3D visualization platform formed the 3D group; 21 patients without 3D visualization assistance formed the control group. Preoperative planning and post-procedural evaluation were performed successfully with the 3D visualization treatment platform. Thermal ablative parameters, survival and recurrence were compared between groups.Results: The primary efficacy rate and recurrence-free survival (RFS) rate in the 3D group were higher than those in the control group (p = .007 and p = .014, respectively). The number of inserted probes in the 3D group was higher than that in the control group (p = .016). The overall survival (OS) rate in the 3D group was comparable to that of controls (p = .745). Estimated 3-year OS and RFS rates were 38.5% and 64.6% in the 3D group and 34.4% and 18.8% in the control group, respectively. Treatment effects were evaluated using a tumor map and confirmed by traditional contrast-enhanced ultrasound in the 3D group. After the first treatment, nine patients (47.4%) achieved complete ablation with a 5-mm safety margin. No major complications related to ablation occurred.Conclusions: US-PMWA assisted by a 3D visualization treatment platform can improve treatment efficiency and appears to be a safe, effective and innovative technique to manage a single large HCC.

Transcatheter arterial chemoembolization combined with radiofrequency or microwave ablation for hepatocellular carcinoma: a review

Hepatocellular carcinoma (HCC) is the sixth most common type of malignancy. Several therapies are available for HCC and are determined by stage of presentation, patient clinical status and liver function. Local–regional treatment options, including transcatheter arterial chemoembolization, radiofrequency ablation or microwave ablation, are safe and effective for HCC but are accompanied by limitations. The synergistic effects of combined transcatheter arterial chemoembolization and radiofrequency ablation/microwave ablation may overcome these limitations and improve the therapeutic outcome. The purpose of this article is to review the current literature on these combined therapies and examine their efficacy, safety and influence on the overall and recurrence-free survival in patients with HCC.

Microwave ablation of benign breast tumors: a prospective study with minimum 12 months follow-up

PURPOSE

This prospective study was to evaluate clinical outcomes of microwave ablation (MWA) of benign breast tumors with minimum 12 months follow up.

METHODS

With approval of the institutional ethics committee and written informed consent, 56 patients with 107 biopsy-proved breast benign tumors were recruited from November, 2013 to April, 2017. MWA with ultrasound (US) guidance was performed under local anesthesia. During the procedure, pull-back technique was used for tumors larger than 1.0 cm in diameter and hydro-dissection technique was used for tumors adjacent to skin, pectoralis and areola. Clinical outcomes were followed up by physical examination and medical images including US, contrast enhanced US and MR.

RESULTS

The maximum diameter of these tumors was 1.6 ± 0.8 cm. MWA was successfully performed with the median 120 s of duration (ranging 20-1100 s). Technical success was achieved in all patients. At the median follow-up of 20.5 months (ranging 12-53 months), the mean volume reduction ratios (mVRRs) of tumors were 77.1 ± 8.2%, 84.3 ± 10.6%, 93.3 ± 8.2% at follow-up of 12, 18, 24 months (p < .0001), respectively. Compared with 92% of masses were palpable before ablation, mass palpabilities were 40%, 11%, 5% at follow-up of 12, 18, 24 months (p < .001), respectively. Cosmetic satisfaction was reported excellent or good in 100% of patients.

CONCLUSIONS

As a safe and effective minimally invasive modality for inactivating benign breast tumors in situ, MWA achieved optimistic clinical outcomes on volume reduction and cosmetic satisfaction after minimum 12 months follow-up.

High power microwave ablation of normal swine lung: impact of duration of energy delivery on adverse event and heat sink effects

PURPOSE

The purpose of this study is to assess the impact of duration of energy delivery on adverse events (AEs) and heat sink effects during high power microwave ablation (MWA) of normal swine lung.

MATERIALS AND METHODS

High power (100 W) MWA was performed with short (2 min, 18 ablations) or long (10 min, nine ablations) duration of energy delivery in unilateral lung of swine (n = 10). CT imaging was done prior to sacrifice at 2 or 28 d post-treatment, with additional imaging at 7 and 14 d for the latter cohort. Ablation zones were assessed with CT imaging and histopathology analysis. Differences in AEs and ablation characteristics between groups were compared with Fisher's exact test and Student's t-test, respectively.

RESULTS

There were no significant differences in formation of air-filled needle tract, cavitation, and pneumonia (p > 0.5) between the treatment groups. Intra-procedural pneumothorax requiring chest tube placement occurred in three animals. Substantial (>20%, p = 0.01) intra-procedural ablation zone distortion was observed in both groups. The presence of large airways or blood vessels did not result in heat sink effect within the ablation zones and was not indicative of reduced ablation size. Increased energy delivery yielded larger (8.9 ± 3.1 cm³ vs. 3.4 ± 1.7 cm³, p < 0.001) spherical ablations (sphericity: 0.70 ± 0.10 vs. 0.56 ± 0.13, p = 0.01).

CONCLUSIONS

High power MWA of normal lung with longer duration of energy delivery can create larger spherical ablations, without significant differences in post-procedure AEs when compared with shorter energy delivery time.

Outcomes of microwave ablation for hepatocellular carcinoma adjacent to large vessels: a propensity score analysis

The aim of this study was to retrospectively compare the long-term efficacy of MW ablation as a curative therapy for hepatocellular carcinoma(HCC) adjacent to large vessels(≥3 mm) with that in safe location. Between 2010 and 2016, 406 patients diagnosed with early-stage HCC at Chinese PLA general hospital were enrolled. One-to-one matched pairs between the vessel group and the safe group were generated using propensity score matching. The associations of treatment strategy with overall survival and local tumor progression were determined by Cox regression. Before matching, 113 patients were classified into the vessel group and 293 patients were classified into the vessel group. The patients in the vessel group were more frequently classified as larger tumor size (P<0.05) and higher AFP level (P<0.05) than patients in the safe group. After propensity score matching, 113 pairs of well-matched HCC patients were selected from different treatment groups. No significant differences were found in local tumor progression, overall survival and complication rates for MW ablation as a first-line treatment for the early-stage HCC between two groups. In conclusion, MW ablation provides an effective and safe way to treat early-stage HCC adjacent to large vessels.

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.

Liver resection surgery versus thermal ablation for colorectal LiVer MetAstases (LAVA): study protocol for a randomised controlled trial

Background

Although surgical resection has been considered the only curative option for colorectal liver metastases (CLM), thermal ablation has recently been suggested as an alternative curative treatment. A prospective randomised trial is required to define the efficacy of resection vs ablation for the treatment of colorectal liver metastases.

Methods

Design and setting: This is a multicentre, open, randomised controlled non-inferiority trial design with internal pilot and will be performed in tertiary liver centres in UK and The Netherlands.

Participants: Eligible patients will be those with colorectal liver metastases at high surgical risk because of their age, co-morbidities or tumour burden and who would be suitable for liver resection or thermal ablation.

Intervention: Thermal ablation as per local policy.

Control: Surgical liver resection performed as per centre protocol.

Co-interventions: Further chemotherapy will be offered to patients as per current practice.

Outcomes

Pilot study: Same as main study and in addition patients and clinicians’ acceptability of the trial to assist in optimisation of recruitment.

Primary outcome: Disease-free survival (DFS) at two years post randomisation.

Secondary outcomes: Overall survival, timing and site of recurrence, additional therapy after treatment failure, quality of life, complications, length of hospital stay, costs, trial acceptability, DFS measured from end of intervention.

Follow-up: 24 months from randomisation; five-year follow-up for overall survival.

Sample size: 330 patients to demonstrate non-inferiority of thermal ablation.

Discussion

This trial will determine the effectiveness and cost-effectiveness of thermal ablation vs surgical resection for high-risk people with colorectal liver metastases, and guide the optimal treatment for these patients.

Trial registration

ISRCTN Registry, ISRCTN52040363. Registered on 9 March 2016.

Electronic supplementary material

The online version of this article (10.1186/s13063-018-2499-5) contains supplementary material, which is available to authorized users.

MoS2 nanosheets encapsulated in sodium alginate microcapsules as microwave embolization agents for large orthotopic transplantation tumor therapy

In recent years, it is prevalent to treat various kinds of the tumors through microwave ablation method. However, it is still very difficult to ablate large tumors by the traditional microwave ablation therapy. In this work, an effective microwave embolization agent designed by encapsulating molybdenum sulfide nanosheets in the sodium alginate microcapsules, denoted as MSMCs, was prepared for the effective therapy of large tumor. The toxicity evaluation showed that MSMC had a good biocompatibility in vitro. The in vitro and in vivo experiments demonstrated that the MSMC was an excellent embolic and microwave susceptible agent that could be used for dual-enhanced microwave ablation therapy. As such, the MSMC showed excellent tumor therapeutic effect with 5 times larger ablation zone observed by magnetic resonance (MR) imaging than the microwave alone after 3 days treating. Besides, the tumor is nearly completely ablated and can not be recurrent due to the persistent hyperthermia. Moreover, MSMCs have a good biocompatibility and can be degraded and cleared from the body. It is believed that the MSMC is demonstrated to be a promising multifunctional theranostic agent used for treating the larger tumor via the synergistic therapy of enhanced microwave ablation and transcatheter arterial embolization (TAE).

Ultrasound-guided percutaneous microwave ablation assisted by three-dimensional visualization operative treatment planning system and percutaneous transhepatic cholangial drainage with intraductal chilled saline perfusion for larger hepatic hilum hepatocellular (D ≥ 3 cm): preliminary results

To assess the clinical efficiency of ultrasound-guided percutaneous microwave ablation (US-PMWA) assisted by three-dimensional (3D) visualization operative treatment planning system and percutaneous transhepatic cholangial drainage with intraductal chilled saline perfusion (PTCD-ICSP) for larger hepatic hilum hepatocellular carcinoma (HH-HCC) (D ≥ 3 cm). The combination therapy was performed in 14 patients from Sep 2011 to May 2017. The major outcomes for assessment were biliary duct complications, local tumor recurrence, distant recurrence and overall survival rates. Median follow-up period was 26 months. The series of 3D visualization operative treatment planning, PTCD-ICSP and US-PMWA were successfully performed and complete ablation was achieved in all cases. The mean session for one tumor was 1.0 ± 0.4. The mean ablation time for per tumor was 1805 ± 567s. The saline volume used for the PTCD-ICSP was 250-450 ml per session. The 1-, 2-, and 3-year local tumor recurrence rates were 7.1%, 14.3%, and 35.7%, the 1-, 2-, and 3-year distant recurrence rates were 0%, 14.3%, and 28.6%, and 1-, 2-, and 3-year overall survival rates were 100%, 92.9%, and 71.4%, respectively. No severe complications related to ablation occurred.

Conclusions

US-PMWA assisted by 3D visualization operative treatment planning system and PTCD-ICSP appears to be a safe, effective and innovative technique for management for larger HH-HCCs, which improved the prognosis.

Does primary tumor location impact the prognosis of colorectal liver metastases patients after microwave ablation? - Lessons from 10 years' experience

Thermal ablation has been considered as an alternative for local curative intent in patients with unresectable colorectal liver metastases. The influence of primary tumor location on the prognosis of colorectal liver metastases patients who have undergone microwave ablation has yet to be determined. We reviewed 295 patients who underwent microwave ablation for colorectal liver metastases at our institution between March 2006 and March 2016. Univariate and multivariate analyses were performed to identify predictors of overall and progression-free survival. Technical success was achieved in 96.6% of patients (n = 289), with a post-procedural complication rate of 2.0% (n = 6). After a median follow-up of 24 (range, 2–86) months, comparable overall survival rates (p = 0.583) were observed in patients with different primary tumor locations. Patients with colorectal liver metastases originating from left-sided primary colon cancer exhibited a better progression-free survival than patients whose colorectal liver metastases had originated from right-sided primary colon cancer (hazard ratio: 0.67, 95.0% confidence interval: 0.48–0.94; p = 0.012), which was further confirmed in a multivariate analysis after adjustment for other potential prognostic factors. Stratification based on primary tumor location should be taken into consideration in the assessment of disease progression in patients who intend to undergo microwave ablation for colorectal liver metastases.

Other non-surgical treatments for liver cancer

Interventional radiology plays a major role in the modern management of liver cancers, in primary hepatic malignancies or metastases and in palliative or curative situations. Radiological treatments are divided in two categories based on their approach: endovascular treatment and direct transcapsular access. Endovascular treatments include mainly three applications: transarterial chemoembolization (TACE), transarterial radioembolization (TARE) and portal vein embolization (PVE). TACE and TARE share an endovascular arterial approach, consisting of a selective catheterization of the hepatic artery or its branches. Subsequently, either a chemotherapy (TACE) or radioembolic (TARE) agent is injected in the target vessel to act on the tumor. PVE raises the volume of the future liver remnant in extended hepatectomy by embolizing a portal vein territory which results in hepatic regeneration. Direct transcapsular access treatments involve mainly three techniques: radiofrequency thermal ablation (RFA), microwave thermal ablation (MWA) and percutaneous ethanol injection (PEI). RFA and MWA procedures are almost identical, their clinical applications are similar. A probe is deployed directly into the tumor to generate heat and coagulation necrosis. PEI has known implications based on the chemical toxicity of intra-tumoral injection with highly concentrated alcohol by a thin needle.

Radiofrequency vs Microwave Ablation After Neoadjuvant Transarterial Bland and Drug-Eluting Microsphere Chembolization for the Treatment of Hepatocellular Carcinoma

AIM

To retrospectively compare the initial response, local recurrence, and complication rates of radiofrequency ablation (RFA) vs microwave ablation (MWA) when combined with neoadjuvant bland transarterial embolization (TAE) or drug-eluting microsphere chemoembolization (TACE) for the treatment of hepatocellular carcinoma (HCC).

METHODS

A total of 35 subjects with Barcelona Clinic Liver Cancer (BCLC) very early and early-stage HCC (range: 1.2-4.1cm) underwent TAE (23) or TACE (12) with RFA (15) or microwave ablation (MWA) (20) from January 2009 to June 2015 as either definitive therapy or a bridge to transplant. TAE and TACE were performed with 40-400μm particles and 30-100μm plus either doxorubicin- or epirubicin-eluting microspheres, respectively. Initial response and local progression were evaluated using modified response evaluation criteria in solid tumors. Complications were graded using common terminology criteria for adverse events version 5.0.

RESULTS

Complete response rates were 80% (12/15) for RFA + TAE/TACE and 95% (19/20) for MWA + TAE/TACE (P = 0.29). Local recurrence rate was 30% (4/12) for RFA + TAE/TACE and 0% (0/19) for MWA + TAE/TACE. Durability of response, defined as local disease control for duration of the study, demonstrated a significant difference in favor of MWA (P = 0.0091). There was no statistical difference in complication rates (3 vs 2).

CONCLUSIONS

MWA and RFA when combined with neoadjuvant TAE or TACE have similar safety and efficacy in the treatment of early-stage HCC. MWA provided more durable disease control in this study; however, prospective data remain necessary to evaluate superiority of either modality.

Status and advancement of microwave ablation in China

Tumour ablation is defined as the direct application of chemical or thermal therapy to eradicate or substantially destroy a tumour. Currently, minimally invasive ablation techniques are available for the local destruction of focal tumours in multiple organ sites. Microwave ablation (MWA) is premised on the biological response of solid tumours to tissue hyperthermia, and it is a relatively low-risk procedure. Due to several advantages of MWA, including higher thermal efficiency, higher capability for coagulating blood vessels, faster ablation time and the simultaneous application of multiple antennae, MWA could be a promising minimally invasive ablation technique for the treatment of solid tumours. Therefore, the use of MWA has developed rapidly in China during the last decade. Many successful studies have been performed, and widespread use has been achieved for multiple types of tumours in China, especially for liver cancer. This review will describe the state-of-the-art of MWA in China, including the development of MWA equipment and its application in the treatment of multiple types of tumours.

Effectiveness of ultrasound-guided percutaneous microwave ablation for symptomatic uterine fibroids: a multicentre study in China

PURPOSE

To evaluate the clinical efficacy of ultrasound-guided percutaneous microwave ablation (PMWA) therapy for symptomatic uterine fibroids in a multicentre study.

MATERIALS AND METHODS

Patients with symptomatic uterine fibroids who underwent PMWA at multiple treatment centres in China between January 2013 and August 2015 were prospectively studied to compare the reduction rate of uterine fibroids, haemoglobin level and uterine fibroid symptom and health-related quality of life questionnaire (UFS-QOL) scores before and at 3, 6 and 12 months after ablation.

RESULTS

A total of 311 patients (405 leiomyomas) from eight treatment centres underwent the treatment (age, 29-55 years; mean ± SD, 41 ± 5.11 years). The mean diameter of the myomas ranged from 2.03 to 12.50 cm (mean, 5.10 ± 1.28 cm) and the volume ranged from 4.40 to 1022.14 cm³ (mean, 95.01 ± 70.29 cm³). Forty-eight myomas were identified as FIGO type 1/2 fibroids, 256 as type 3/4 fibroids and 101 as type 5/6 fibroids. The mean ablation rate was 86.6% (54.0-100%). The mean reduction rate was 63.5%, 78.5% and 86.7% at 3, 6 and 12 months posttreatment, respectively. The haemoglobin level increased significantly from 88.84 ± 9.31 g/L before treatment to 107.14 ± 13.32, 116.05 ± 7.66 and 117.79 ± 6.51 g/L at 3, 6 and 12 months posttreatment, respectively (p = .000). The symptom severity score (SSS) and health-related quality of life (HRQL) scores were also significantly improved posttreatment compared with before treatment (p = .000).

CONCLUSION

PMWA is an effective, minimally invasive treatment for symptomatic leiomyomas that can significantly improve the quality of life of patients.

Combination of microbubbles and diagnostic ultrasound at a high mechanical index for the synergistic microwave ablation of tumours

OBJECTIVES

To determine whether combining microbubbles (MBs) with diagnostic ultrasound (US) at a high mechanical index (MI) could enhance the microwave (MW) ablation of tumours.

MATERIALS AND METHODS

Five therapeutic MW adjuvant protocols were studied: MW, MW + US, MW + US + MB, MW + US + NS (saline) and MW + MB. In 30 normal rabbit livers, the synergistic effects were evaluated via temperature, necrosis volume and histology. In 90 VX2 rabbit hepatic tumours, residual cells in the peripheral ablated tumours were examined via immunohistochemical assay and tumour growth. Additional 40 VX2 hepatic tumours were evaluated for ablation safety via blood assay and weight and for survival to 105 days. Results were compared using analysis of variance.

RESULTS

Compared with the other protocols, the ablation volumes in normal rabbit livers were significantly larger using the MW + US + MB protocol (p < .001). The histological examination was consistent with more efficient ablation in that protocol. In detecting residual cells, the apoptotic index was higher, the proliferating index was lower (p < .05), tumour growth was significantly smaller (p < .001), and the rabbits of the MW + US + MB T-Group survived longer (p < .05) than those of the other groups. Additionally, no damage to the liver function or blood cells was found in any of the protocols after ablation (p < .05).

CONCLUSIONS

MBs in combination with diagnostic US at a high MI showed potential synergy in the MW ablation of tumours in rabbits.

Ultrasound-Guided Percutaneous Microwave Ablation for Hepatocellular Carcinoma in the Caudate Lobe

Treatment for liver tumors in the caudate lobe is challenging because of their location and complex anatomy. This study was intended to evaluate the feasibility, efficacy and tolerability of ultrasound-guided percutaneous microwave (MW) ablation for treating hepatocellular carcinoma (HCC) in the caudate lobe. From December 2011 to May 2015, a total of 20 patients (mean age: 62 ± 11 y) with HCC in the caudate lobe were enrolled in this study. Patient characteristics and tumor features were analyzed. The epigastric approach, intercostal approach and the combination were used in 4, 14 and 2 patients, respectively. Contrast-enhanced ultrasound (CEUS) guidance and temperature monitoring were applied as ancillary techniques. Ethanol injection was performed for tumors adjacent to the inferior vena cava or hepatic hilum. Contrast images were performed to evaluate treatment response after ablation. Technical success, technique efficacy, local tumor progression and complications were documented. Technique efficacy was achieved in 18 patients (18/20, 90%). Two patients received (125)I brachytherapy as palliative therapy for residual tumors that could not be ablated technically after the first ablation. Technical success was achieved in 16 patients (16/20, 80%). In 2 patients, ablation was completed after two sessions. CEUS was applied in 5 patients and temperature monitoring in 2 patients. Eight patients received an ethanol injection during ablation. Eleven patients achieved a minimum 5-mm safety margins. Local tumor progression was detected in 3 patients (16.7%, 3/18) during a median follow-up of 18.4 mo (range: 3-45 mo). Tumors in these 3 patients were all larger than 2.0 cm. No major or minor complications were observed. In conclusion, ultrasound-guided percutaneous microwave ablation combined with CEUS, temperature monitoring, and ethanol injection is a tolerable and relatively effective treatment for HCC in the caudate lobe.

Morphometric and chronological behavior of 2.45 GHz microwave ablation zones for colorectal cancer metastases and hepatocellular carcinoma in the liver: preliminary report

BACKGROUND

Percutaneous microwave ablation (MWA) is increasingly utilized in the treatment of primary and secondary hepatic malignancy. As an in-situ treatment appreciation of any signs of recurrence is critical for improving long-term oncological outcomes. Volumetry has been recognized as having advantages over orthogonal measurements in the response assessment of malignant lesions. Our study set out to look at the normal involution of an ablation zone (AZ) both volumetrically and morphologically to see if this information might aid the detection of local tumor progression.

METHODS

Cases were identified retrospectively from our database of liver MWA. We identified 34 AZs in total, 18 AZs in 16 hepatocellular carcinoma (HCC) patients with cirrhosis on imaging grounds and 13 AZs in patients with metastatic colorectal cancer. How these AZs developed over time was analyzed both morphologically and quantitatively using Siemens Syngo Via post-processing software. We used the software to produce volume measurements and short axis orthogonal measurements. A baseline measurement was taken on the first <30 day post-ablation scan and the chronological changes were then plotted.

RESULTS

We saw differences between the cirrhotic and non-cirrhotic patients both in terms of morphological and volumetric changes. 12/13 non-cirrhotic AZs had a volume of <50% of the baseline scan within the first year. The cirrhotic patients were less predictable, but 14/18 still shrunk to less than 50% of baseline volume in the first year. Orthogonal measurements were less useful in both groups. Qualitatively, there was initially a slightly less well-defined border to the AZ in the first 3 months, which became better defined over time and certainly over the first year of AZ involution.

CONCLUSION

Volumetric analysis is a useful adjunct to conventional measurements and qualitative analysis of AZs. This can be reassuring when orthogonal measurements are static or difficult to interpret. Our preliminary data suggest that the normal pattern in a non-cirrhotic liver is that the AZ volume should drop below 50% of baseline at 1 year. Volumes in cirrhotic livers are less predictable, but the majority will still follow a similar pattern. Future studies could evaluate if failure to follow these patterns correlates with local tumor progression.

Bridging and downstaging therapy in patients suffering from hepatocellular carcinoma waiting on the list of liver transplantation

Hepatocellular carcinoma (HCC) is a common primary malignancy worldwide especially in the patients with the background of chronic liver disease. Liver transplantation (LT) is the only curative treatment effective for both malignancy as well as the cirrhosis and portal hypertension. Unfortunately, living donor is not always possible and the deceased graft is scarce. Neoadjuvant therapies, therefore, have been developed as a downstaging treatment to try to downstage the tumor within the transplant criteria, or as a bridging therapy to control the tumor growth in patients while waiting in the transplant list. This paper reviewed the common modalities used as bridging and downstaging therapies for patients suffering from HCC before undergoing LT.

Microwave ablation for liver tumors

Surveillance programs and widespread use of medical imaging have increased the detection of hepatic tumors. When feasible, surgical resection is widely accepted as the curative treatment of choice, but surgical morbidity and mortality has spurred the development of minimally invasive ablative technologies over the last 2 decades. Microwave ablation has emerged as a promising thermal ablation modality with improving oncologic efficacy due to technical improvements and image guidance strategies. This article provides an overview of microwave application in liver tumors, and we discuss currently available equipment, clinical efficacy, and safety and provide comparisons with other commonly used therapies. This article also introduces advanced ablative techniques and combination therapies that may help achieve precise ablation and further enhance the efficacy of microwave ablation.

Percutaneous microwave ablation vs radiofrequency ablation in the treatment of hepatocellular carcinoma

Hepatocellular cancer ranks fifth among cancers and is related to chronic viral hepatitis, alcohol abuse, steatohepatitis and liver autoimmunity. Surgical resection and orthotopic liver transplantation have curative potential, but fewer than 20% of patients are suitable candidates. Interventional treatments are offered to the vast majority of patients. Radiofrequency (RFA) and microwave ablation (MWA) are among the therapeutic modalities, with similar indications which include the presence of up to three lesions, smaller than 3 cm in size, and the absence of extrahepatic disease. The therapeutic effect of both methods relies on thermal injury, but MWA uses an electromagnetic field as opposed to electrical current used in RFA. Unlike MWA, the effect of RFA is partially limited by the heat-sink effect and increased impedance of the ablated tissue. Compared with RFA, MWA attains a more predictable ablation zone, permits simultaneous treatment of multiple lesions, and achieves larger coagulation volumes in a shorter procedural time. Major complications of both methods are comparable and infrequent (approximately 2%-3%), and they include haemorrhage, infection/abscess, visceral organ injury, liver failure, and pneumothorax. RFA may incur the additional complication of skin burns. Nevertheless, there is no compelling evidence for differences in clinical outcomes, including local recurrence rates and survival.

Comparison of 3D ultrasound and magnetic resonance imaging for microwave ablation in the canine splenomegaly model

PURPOSE

Microwave ablation is used for the treatment of hypersplenism. Image guidance and ablation volume assessment is important to ensure that the ablation is successful. The accuracy of 3D ultrasound (US) and magnetic resonance imaging (MRI) in determining the parameters for microwave ablation were compared in a canine splenomegaly model.

METHODS

Microwave ablation of the spleen was performed on 13 dogs with congestive splenomegaly. Several combinations of power output and ablation time were used: 60 W for 300 s, 50 W for 360 s and 40 W for 450 s. The ablation zone volume was measured by 3D US and 3D MRI immediately after microwave ablation, and at 1, 2 and 8 weeks thereafter.

RESULTS

Compared with 3D MRI, the ablation zone reconstruction rate was lower with 3D US (92 vs. 100%). However, there was no significant difference was found in the ablation volume calculated soon after the treatment and 1 week and 2 months later.

CONCLUSION

3D US may be useful for quantifying the volume of microwave ablation zones in the spleens of experimental animals and appears promising as an alterative modality to MRI for clinical examinations.