Percutaneous microwave ablation of exophytic tumours in hepatocellular carcinoma patients: Safe or not?

Imaging Classification of Exophytic HCC and Our Experience with Microwave Ablation of Type 2 Lesions

Purpose  The purpose of this article is to classify hepatocellular carcinoma (HCC) based on imaging and to evaluate the role of ultrasound-guided microwave ablation (MWA) in the management of type 2 exophytic HCC. Materials and Methods  A retrospective study was performed at our institution after approval by the Institutional Review Board. The study was undertaken from January 2017 to May 2022. Based on the location, HCC was classified and categorized on cross-sectional imaging into four types. All MWA procedures were performed using ultrasound guidance. Patients were followed up every 3 months with cross-sectional imaging. Results  During the study period, 225 lesions were reviewed. MWA was performed in 13 type 2 exophytic HCC patients. Segment 3 (38%) was the most common site when categorized as per Couinaud classification and segment 6 was the next common site. Technical success of complete ablation, evaluated by postprocedure contrast-enhanced computed tomography scan, was 100%. The median follow-up period was 24 months (range: 9-24 months). One patient presented with a residual lesion on the first follow-up at 30 days. Two other patients followed up to 9 months were free of HCC. Ten patients followed up at 1 year showed no recurrence, while 7 of them were followed up for 24 months, and 1 of whom showed multicentric recurrence which was treated by selective intra-arterial radiation therapy. Conclusion  A classification system for exophytic lesions can allow for better patient selection, planning, and reporting of ablative outcomes. MWA has performed well when ablating these technically challenging lesions with a certain degree of planning.

Achieving Complete Tumor Clearance: A Minimalist Manganese Hydrogel for Magnetic Resonance Imaging-Guided Synergetic Microwave Ablation and Chemodynamic Therapy

The combination of microwave ablation (MWA) and chemodynamic therapy (CDT) presents a promising strategy for complete eradication of residual tumor after MWA. However, it remains challenging and urgent to develop a facile, biocompatible, and imaging-guided platform for the achievement of this goal. Herein, a minimalist manganese hydrogel (ALG-Mn hydrogel) is proposed for synergistic MWA and CDT to completely eradicate tumor in vivo. The ALG-Mn hydrogel is prepared using a simple mixing method and exhibits excellent syringeability, remarkable microwave sensitivity, and potent Fenton-like activity. By assisting in MWA procedures, the ALG-Mn hydrogel enables both elimination of primary tumor mass through enhanced MWA efficacy and eradication of potential residual tumor tissues via robust CDT. This approach achieves complete tumor clearance without additional drug loading. Furthermore, the paramagnetic Mn2+ component allows real-time dynamic visualization of the ALG-Mn hydrogel at the tumor site via magnetic resonance imaging. To the best of knowledge, the proposed ALG-Mn hydrogel represents the minimalist biocompatible platform for imaging-guided synergistic MWA and CDT toward achieving complete tumor clearance.

Anatomical thermal ablation as an alternative to surgical resection for subcapsular hepatocellular carcinoma

PURPOSE

To simulate the advantages of anatomical resection, a new strategy of anatomical thermal ablation was proposed. The objective of this study was to evaluate the clinical value of anatomical thermal ablation (ATA) to treat subcapsular hepatocellular carcinoma by comparing it with anatomical resection (AR) and non-anatomical resection (NAR).

METHODS

This retrospective cohort study enrolled hepatocellular carcinoma patients with subcapsular tumor diameter ≤ 50 mm treated by ATA or surgical resection at our center from October 2015 to December 2018. ATA features ablation of the Glisson capsule, ablation of the liver parenchyma between the tumor and hepatic veins or inferior vena cava and then puncture from the surrounding part to the central part of the tumor. Outcome parameters were compared.

RESULTS

Seventy-six patients were grouped into ATA group, 95 patients into AR group and 41 patients into NAR group. The 1-, 2-, and 3-year local recurrence rates were 0.0%, 0.0%, 0.0% for ATA group, 0.0%, 1.4%, 1.4% for the AR group and 0.0%, 0.0%, and 0.0% for the NAR group, respectively (P = 0.449). The 1-, 2-, and 3-year progression-free survival rates were 90.6%, 80.9%, and 74.6% for ATA group, 91.5%, 80.2%, and 80.2% for the AR group and 82.9%, 73.8%, and 73.8% for the NAR group, respectively (P = 0.608). The 1-, 2-, and 3-year overall survival rates were 100.0%, 95.2%, and 95.2% for the ATA group, 96.8%, 95.6%, and 95.6% for the AR group and 97.6%, 95.0%, and 95.0% for the NAR group, respectively (P = 0.970). No difference was found in major complication rate among these groups (P = 0.091).

CONCLUSION

For subcapsular hepatocellular carcinoma, ATA could be an alternative to surgical resection with its comparable treatment effect and safety.

Microwave ablation for hepatic malignancies: a systematic review of the technology and differences in devices

BACKGROUND

Microwave ablation (MWA) has become the standard thermal-based treatment for hepatic malignancies in patients who have unresectable disease based on the biology of the tumor, the patients' comorbidities, and certain disease sites. The technical effectiveness, ablation success, local recurrence rates of hepatic malignancies treated with the various commercial microwave ablation devices has not been previously published in the peer reviewed literature. The aim of this systematic review is to summarize the clinical outcomes for the various MWA devices in the use of a hepatic malignancies to best educate hepatic surgeons as well as interventional radiologists.

METHODS

A comprehensive review of the literature and instructions for use of each device that was published from 1/2013 to 12/2020 was performed. The main outcomes extracted were technical success, ablation success, major complications, local and new recurrence rates, recurrence-free survival, ablation volumes, time, and the number of antennas required. A qualitative review of the literature was performed.

RESULTS

In total, 29 studies reporting data on 3250 patients and 4500 tumors were included in this review. Median patient age was 60.5 years (range 3-91). 76.3% (2420 M/753 F) of patients were male. Hepatocellular carcinoma (55%) was the most common tumor pathology followed by colorectal liver metastasis (10%) and cholangiocarcinoma (4%). A majority of studies reported technical success (range, 91.6-100%) and ablation success (range, 73.1-100%), as well as major complications (range, 0-9.1%). Local recurrence (range, 0-50%) was reported by 21 of the studies; however, new recurrence (range, 12.2-64%) was reported less frequently (6 studies) and were further specified in 12, six, and four studies as intrahepatic distant recurrence (11.3-54.2%), extrahepatic distant recurrence (3.6-20%), and metastasis (1.1-36%). A total of three, six, and five studies report disease, progression, and recurrence-free survival rates, respectively.

CONCLUSION

Microwave ablation is frequently used for the treatment of hepatic malignancies. A thorough understanding of the clinical outcomes associated with different pathologies and MWA devices can improve surgeon awareness and help prepare for operative planning and patient management. More consistent reporting of key outcomes in the literature is needed to achieve such an understanding.

Image-guided locoregional non-intravascular interventional treatments for hepatocellular carcinoma: Current status

Hepatocellular carcinoma (HCC) is one of the most deadly and frequent cancers worldwide, although great advancement in the treatment of this malignancy have been made within the past few decades. It continues to be a major health issue due to an increasing incidence and a poor prognosis. The majority of patients have their HCC diagnosed at an intermediate or advanced stage in theUSA or China. Curative therapy such as surgical resection or liver transplantation is not considered anoption of treatment at these stages.

Transarterial chemoembolization (TACE), the most widely used locoregional therapeutic approach, used to be the mainstay of treatment for cases with unresectable cancer entities. However, for those patients with hypovascular tumors or impaired liver function reserve, TACE is a suboptimal treatment option. For example, embolization does not result in complete coverage of a hypovascular tumor, and may rather promotes postoperative tumor recurrence, or leave residual tumor, in these TACE-resistance patients. In addition, TACE carries a higher risk of hepatic decompensation in patients with poor liver function or reserve.

Non-vascular interventional locoregional therapies for HCC include radiofrequency ablation (RFA), microwave ablation (MWA), high-intensity focused ultrasound (HIFU), laser-induced thermotherapy (LITT), cryosurgical ablation (CSA), irreversible Electroporation (IRE), percutaneous ethanol injection (PEI), and brachytherapy. Recent advancements in these techniques have significantly improved the treatment efficacy of HCC and expanded the population of patients who qualify for treatment. This review embraces the current status of imaging-guided locoregional non-intravascular interventional treatments for HCCs, with a primary focus on the clinical evaluation and assessment of the efficacy of combined therapies using these interventional techniques.

Nomograms to predict survival outcomes after microwave ablation in elderly patients (>65 years old) with early-stage hepatocellular carcinoma

Objectives: To develop and validate the nomograms to predict survival outcomes after microwave ablation (MWA) in elderly patients(>65 years old) with early-stage hepatocellular carcinoma (EHCC).Methods: This retrospective study was approved by the institutional review board. A total of 265 EHCC patients (76 females, 189 males; average age 71.4 years ± 5.4 [standard deviation]) with 345 nodules subsequently underwent MWA from April 2006 to October 2019. Baseline characteristics were collected to identify the risk factors for the determination of survival outcomes after MWA. The nomograms were based on prognostic factors for overall survival (OS) and recurrence-free survival (RFS) from the multivariate Cox proportional hazards model and validated in external cohorts from another two institutions (n = 130). The nomograms were assessed for their predictive accuracy using Harrell's concordance index (C-index).Results: After a median follow-up time of 28.6 months, 29.8% (79/265) of the patients died, and 54.3% (144/265) of the patients experienced recurrence in the training set. The OS nomogram was developed based on the hepatitis B virus (HBV) presence, α-fetoprotein (AFP), and albumin, with a C-index of 0.757 (95% confidence interval [CI]: 0.645, 0.789).The scores of the nomogram ranged from 0 to 24. The RFS nomogram was developed based on tumor number, abutting major vessels and platelets, with a C-index of 0.733 (CI: 0.672, 0.774). The likelihood of 3- and 5-year OS and RFS were consistent between clinical observations and nomogram predictions in external cohorts.Conclusions: The nomogram models can be useful in determining the risk of OS and RFS in elderly patients with EHCC after MWA, which can guide individual patient management.Key pointsMWA is an effective and feasible treatment for elderly patients with EHCC and can improve survival outcomes.A calibrated and objective nomogram model for the prediction of survival outcomes in elderly patients (>65 years old) may guide patient selection and MWA treatment.Older age was not deemed to be a risk factor for survival outcomes when the elderly patients with EHCC underwent MWA.

A review on radiofrequency, microwave and high-intensity focused ultrasound ablations for hepatocellular carcinoma with cirrhosis

Importance

Hepatocellular carcinoma (HCC) is usually accompanied by liver cirrhosis, which makes treatment of this disease challenging. Liver transplantation theoretically provides an ultimate solution to the disease, but the maximal surgical stress and the scarcity of liver graft make this treatment option impossible for some patients. In an ideal situation, a treatment that is safe and effective should provide a better outcome for patients with the dilemma.

Objective

This article aims to give a comprehensive review of various types of loco-ablative treatment for HCC.

Evidence Review

Loco-ablative treatment bridges the gap between surgical resection and transarterial chemotherapy. Various types of ablative therapy have their unique ability, and evidence-based outcome analysis is the most important key to assisting clinicians to choose the most suitable treatment modality for their patients.

Findings

Radiofrequency ablation (RFA) has a relatively longer history and more evidence to support its effectiveness. Microwave ablation (MWA) is gaining momentum because of its shorter ablation time and consistent ablation zone. High-intensity focused ultrasound (HIFU) ablation is a relatively new technology that provides non-invasive treatment for patients with HCC. It has been carried out at centers of excellence and it is a safe and effective treatment option for selected patients with HCC and liver cirrhosis.

Conclusion and Relevance

Selective use of different loco-ablative therapies will enhance clinicians' treatment options for treatment of HCC.

Predicting the survival rate of patients with hepatocellular carcinoma after thermal ablation by nomograms

Background

To accurately predict the survival rate of patients with hepatocellular carcinoma (HCC) undergoing thermal ablation using nomograms taking early recurrence into account as a risk factor.

Methods

A total of 591 patients receiving percutaneous thermal ablation were included in this study. The overall survival (OS) and recurrence-free survival (RFS) rate was analyzed. Two prognostic nomograms with or without taking early recurrence into account as a risk factor were constructed using the independent predictors assessed by the multivariate Cox proportional hazard model. The performance of the nomograms, in terms of discrimination and calibration, was evaluated.

Results

The cumulative RFS and OS rates at 1-, 3- and 5-year are 82.2%, 52.5%and 38.4%, 96.6%, 83.6% and 65.5%, respectively. Multivariate analysis without considering the early recurrence shows that tumor number, α-fetoprotein (AFP) level, liver function, and GGT level are associated with OS. The early recurrence, tumor number, AFP level, and liver function are considered associated with the OS when considering early recurrence. Two different nomograms were developed from the above two results. Internal validation with 1,000 bootstrapped sample sets of the two nomograms shows the concordance indexes of 0.69 (95% CI: 0.624-0.748) for the baseline nomogram and 0.81 (95% CI: 0.754-0.857) for the early recurrence-based nomogram, with the latter significantly better in discriminating performance (Z statistics =92.19, P<0.0001).

Conclusions

The survival rate of patients with HCC undergoing radical thermal ablation can be reliably predicted by the nomogram presented in this study, which was developed by taking early recurrence into account.

The Learning Curve for Thermal Ablation of Liver Cancers: 4,363-Session Experience for a Single Central in 18 Years

This study aimed to explore the special efforts required to achieve proficiency in performing thermal ablation of liver cancers, including tumors in difficult locations, and clarify the effects of handing-down teaching on the corresponding process. Major complications of patients receiving percutaneous thermal ablation of liver cancer were analyzed. Polynomial fitting was used to describe the connection between major complication rates and special experience. Learning curve of major complications was plotted both for the whole group and for each operator, respectively. Tumors in difficult locations were further studied. A total of 4,363 thermal ablation sessions were included in this study. 143 of 4,363 patients had major complications, corresponding to an incidence rate of 3.27%. 806 thermal ablation sessions were performed for tumors in difficult locations. The major complication rate of these sessions is 6.33%. According to the trend of the learning curve of the 4363 patients, the experience of the whole group can be classified into five stages, that is, the high-risk, relatively stable, unstable, proficient and stable periods. A learning curve for an individual operator can be classified into the high-risk, proficient and stable periods. The major complication rates for the chronologically first, second and third operator of the group are 3.23, 3.35, and 3.31%, respectively. The special experience needed to bypass the first stage corresponds to 410, 510, and 440 sessions, the second stage, 1850, 850, and 870 sessions, by the three operators, respectively. The major complication rates for the tumors in difficult locations for the first, second and third operator were 7.04, 5.53, and 5.98%, respectively. For the tumors in difficult locations, the special experience needed to bypass the first stage corresponds to 150, 130, and 140 sessions, the second stage, 290, 175, and 185 sessions, by the three operators, respectively. In conclusion, the learning process of an operator percutaneous thermal ablation for liver cancer can be classified into three stages. The major complication rate for tumors in difficult locations were higher than that for all tumors. Handing-down teaching can make an operator arrive at the third stage earlier but not the second stage.

Color coded perfusion analysis and microcirculation imaging with contrast enhanced ultrasound (CEUS) for post-interventional success control following thermal ablative techniques of primary and secondary liver malignancies

AIM

Evaluation of the post-interventional success following ablative techniques (radiofrequency and microwave) using a new color coded perfusion quantification software with CEUS in patients with primary and secondary liver malignancies.

MATERIAL AND METHODS

75 patients (60 males, 15 females, age 24-84 years, mean 62.7 years) with 128 malignant liver lesions were included in this study. Between 01/2013 and 06/2018, the therapeutic interventional procedure in 88 lesions was MWA, in 40 lesions RFA. All patients underwent CEUS using a convex multifrequency probe (1-6 MHz) following application of 1-2.4 ml sulphur hexaflouride microbubbles, before and within 24 hours following RFA and MWA to detect residual tumor tissue. Postprocessing of the stored DICOM loops from 15 sec up to 1 min using a perfusion quantification software regarding peak enhancement (pE), time to peak (TTP), mean transit time (MTT), rise time (Ri) and Wash-in area under the curve (WiAUC) in the center of the lesion, the border area and periphery was performed.

RESULTS

In patients treated with RFA, pE differences between center of the lesion vs. surrounding liver were found to be statistically extremely significant (p < 0.001), differences between center of the lesion and margin were also statistically significant (p < 0.01). mTT, TTP, WiAuC and Ri showed no significant difference between center, margin or surrounding liver.In patients treated with MWA, statistically significant differences (p < 0.05) were found for pE, Ri and mTT regarding the differences between center of lesion and surrounding tissue. WiAuC and TTP showed no significant differences between center, margin or surrounding liver.

CONCLUSION

CEUS with perfusion imaging is a valuable supporting tool for post-interventional success control following RFA and MWA of primary and secondary liver maligancies. Focus should be placed upon pE following MWA and pE, Ri and mTT following RFA.

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.

Percutaneous treatment of hepatocellular carcinoma: State of the art and innovations

Percutaneous treatment of hepatocellular carcinoma (HCC) encompasses a vast range of techniques, including monopolar radiofrequency ablation (RFA), multibipolar RFA, microwave ablation, cryoablation and irreversible electroporation. RFA is considered one of the main curative treatments for HCC of less than 5 cm developing on cirrhotic liver, together with surgical resection and liver transplantation. However, controversies exist concerning the respective roles of ablation and liver resection for HCC of less than 3 to 5 cm on cirrhotic liver. In line with the therapeutic algorithm of early HCC, percutaneous ablation could also be used as a bridge to liver transplantation or in a sequence of upfront percutaneous treatment, followed by transplantation if the patient relapses. Moreover, several innovations in ablation methods may help to efficiently treat early HCC, initially considered as "non-ablatable", and might, in some cases, extend ablation criteria beyond early HCC, enabling treatment of more patients with a curative approach.