Microwave ablation of liver malignancies: comparison of effects and early outcomes of percutaneous and intraoperative approaches with different liver conditions : New advances in interventional oncology: state of the art

Optimizing microwave ablation planning with the ablation success ratio

The size of hepatic microwave ablations (MWA) is often difficult to predict due to cooling effects from liver vessels. This study introduces a simplified predictive model, the Ablation Success Ratio (ASR), which estimates the likelihood of a successful ablation based on tumor size and specific ablation parameters. The ASR model is based on the three-dimensional minimum ablation radius (r3Dmin), defining the spherical region within which complete ablation is achieved. To validate the ASR, standardized MWAs were performed in an ex vivo porcine liver model using a glass tube to simulate the vascular cooling effect. Ablations (n = 148) were conducted at 100 W for 5 min, with antenna-to-vessel (A-V) distances set at 2.5, 5.0, and 10.0 mm. Subsequently, the r3Dmin was calculated. Without vascular cooling (0 ml/min, corresponding to an intraoperative Pringle maneuver), an ASR of 100% was achieved for ablation diameters up to 20 mm. However, in the presence of vascular cooling (1-500 ml/min), the ASR reached 100% only for ablation diameters up to 12 mm, demonstrating that the ASR effectively includes the impact of vascular cooling effects. The ASR is a promising and simple approach for predicting ablation success while also accounting for vascular cooling effects in hepatic MWA.

Recent advancements in management for noncolorectal, nonneuroendocrine hepatic metastases

BACKGROUND

Owing to the heterogeneity of underlying primary tumors, noncolorectal, nonneuroendocrine metastases to the liver (NCNNMLs), although relatively rare, pose major challenges to treatment and long-term management. Despite being considered the gold standard for colorectal cancer liver metastases, the role of surgical resection for NCNNML remains controversial. Furthermore, advancements in locoregional treatment modalities, such as ablation and various chemotherapeutic modalities, have contributed to the treatment of patients with NCNNML.

METHODS

This was a comprehensive review of literature that used Medline/PubMed, Google Scholar, the Cochrane Library, and the Web of Science, which were accessed between 2014 and 2024.

RESULTS

NCNNMLs are rare tumor entities with varied presentation and outcomes. A multidisciplinary approach, which includes chemotherapy, surgery, and interventional radiologic techniques, can be implemented with good results.

CONCLUSION

Given the complex nature of NCNNML, its management should be highly individualized and multidisciplinary. Locoregional treatments, such as surgical resection and/or ablation, may be more appropriate for select patients and should be offered as a viable therapeutic option for a subset of individuals.

Contribution and advances of robotics in percutaneous oncological interventional radiology

The advent of robotic systems in interventional radiology marks a significant evolution in minimally invasive medical procedures, offering enhanced precision, safety, and efficiency. This review comprehensively analyzes the current state and applications of robotic system usage in interventional radiology, which can be particularly helpful for complex procedures and in challenging anatomical regions. Robotic systems can improve the accuracy of interventions like microwave ablation, radiofrequency ablation, and irreversible electroporation. Indeed, studies have shown a notable decrease of an average 30% in the mean deviation of probes, and a 40% lesser need for adjustments during interventions carried out with robotic assistance. Moreover, this review highlights a 35% reduction in radiation dose and a stable-to-30% reduction in operating time associated with robot-assisted procedures compared to manual methods. Additionally, the potential of robotic systems to standardize procedures and minimize complications is discussed, along with the challenges they pose, such as setup duration, organ movement, and a lack of tactile feedback. Despite these advancements, the field still grapples with a dearth of randomized controlled trials, which underscores the need for more robust evidence to validate the efficacy and safety of robotic system usage in interventional radiology.

Tissue Ablation: Applications and Perspectives

Tissue ablation techniques have emerged as a critical component of modern medical practice and biomedical research, offering versatile solutions for treating various diseases and disorders. Percutaneous ablation is minimally invasive and offers numerous advantages over traditional surgery, such as shorter recovery times, reduced hospital stays, and decreased healthcare costs. Intra-procedural imaging during ablation also allows precise visualization of the treated tissue while minimizing injury to the surrounding normal tissues, reducing the risk of complications. Here, the mechanisms of tissue ablation and innovative energy delivery systems are explored, highlighting recent advancements that have reshaped the landscape of clinical practice. Current clinical challenges related to tissue ablation are also discussed, underlining unmet clinical needs for more advanced material-based approaches to improve the delivery of energy and pharmacology-based therapeutics.

SAGES/AHPBA guidelines for the use of microwave and radiofrequency liver ablation for the surgical treatment of hepatocellular carcinoma or colorectal liver metastases less than 5 cm

BACKGROUND

Primary hepatocellular carcinoma (HCC) and colorectal liver metastases (CRLM) represent the liver's two most common malignant neoplasms. Liver-directed therapies such as ablation have become part of multidisciplinary therapies despite a paucity of data. Therefore, an expert panel was convened to develop evidence-based recommendations regarding the use of microwave ablation (MWA) and radiofrequency ablation (RFA) for HCC or CRLM less than 5 cm in diameter in patients ineligible for other therapies.

METHODS

A systematic review was conducted for six key questions (KQ) regarding MWA or RFA for solitary liver tumors in patients deemed poor candidates for first-line therapy. Subject experts used the GRADE methodology to formulate evidence-based recommendations and future research recommendations.

RESULTS

The panel addressed six KQs pertaining to MWA vs. RFA outcomes and laparoscopic vs. percutaneous MWA. The available evidence was poor quality and individual studies included both HCC and CRLM. Therefore, the six KQs were condensed into two, recognizing that these were two disparate tumor groups and this grouping was somewhat arbitrary. With this significant limitation, the panel suggested that in appropriately selected patients, either MWA or RFA can be safe and feasible. However, this recommendation must be implemented cautiously when simultaneously considering patients with two disparate tumor biologies. The limited data suggested that laparoscopic MWA of anatomically more difficult tumors has a compensatory higher morbidity profile compared to percutaneous MWA, while achieving similar overall 1-year survival. Thus, either approach can be appropriate depending on patient-specific factors (very low certainty of evidence).

CONCLUSION

Given the weak evidence, these guidelines provide modest guidance regarding liver ablative therapies for HCC and CRLM. Liver ablation is just one component of a multimodal approach and its use is currently limited to a highly selected population. The quality of the existing data is very low and therefore limits the strength of the guidelines.

Emprint Microwave Thermoablation System: Bridging Thermal Ablation Efficacy between Human Patients and Porcine Models through Mathematical Correlation

To investigate the in vivo ablation characteristics of a microwave ablation antenna in the livers of humans with tumors, a retrospective analysis of the ablation zones was conducted after applying Emprint microwave ablation systems for treatment. Percutaneous microwave ablations performed between January 2022 and September 2022 were included in this study. Subsequently, immediate post-ablation echography images were subjected to retrospective evaluation to state the long ablated diameter, short ablated diameter, and volume. The calculated ablation lengths and volume indices were then compared between in vivo and ex vivo results obtained from laboratory experiments conducted on porcine liver. The ex vivo data showed a good correlation between energy delivered and both increasing ablated dimensions (both p < 0.001) and volume (p < 0.001). The in vivo data showed a good correlation for dimensions (p = 0.037 and p = 0.019) and a worse correlation for volume (p = 0.142). When comparing ex vivo and in vivo data for higher energies, the ablated volumes grew much more rapidly in ex vivo cases compared to in vivo ones. Finally, a set of correlations to scale ex vivo results with in vivo ones is presented. This phenomenon was likely due to the absence of perfusion, which acts as a cooling system.

Surgical approach to microwave and radiofrequency liver ablation for hepatocellular carcinoma and colorectal liver metastases less than 5 cm: a systematic review and meta-analysis

BACKGROUND

Primary hepatocellular carcinoma (HCC) and colorectal liver metastases (CRLM) represent the two most common malignant neoplasms of the liver. The objective of this study was to assess outcomes of surgical approaches to liver ablation comparing laparoscopic versus percutaneous microwave ablation (MWA), and MWA versus radiofrequency ablation (RFA) in patients with HCC or CRLM lesions smaller than 5 cm.

METHODS

A systematic review was conducted across seven databases, including PubMed, Embase, and Cochrane, to identify all comparative studies between 1937 and 2021. Two independent reviewers screened for eligibility, extracted data for selected studies, and assessed study bias using the modified Newcastle Ottawa Scale. Random effects meta-analyses were subsequently performed on all available comparative data.

RESULTS

From 1066 records screened, 11 studies were deemed relevant to the study and warranted inclusion. Eight of the 11 studies were at high or uncertain risk for bias. Our meta-analyses of two studies revealed that laparoscopic MW ablation had significantly higher complication rates compared to a percutaneous approach (risk ratio = 4.66; 95% confidence interval = [1.23, 17.22]), but otherwise similar incomplete ablation rates, local recurrence, and oncologic outcomes. The remaining nine studies demonstrated similar efficacy of MWA and RFA, as measured by incomplete ablation, complication rates, local/regional recurrence, and oncologic outcomes, for both HCC and CRLM lesions less than 5 cm (p > 0.05 for all outcomes). There was no statistical subgroup interaction in the analysis of tumors < 3 cm.

CONCLUSION

The available comparative evidence regarding both laparoscopic versus percutaneous MWA and MWA versus RFA is limited, evident by the few studies that suffer from high/uncertain risk of bias. Additional high-quality randomized trials or statistically matched cohort studies with sufficient granularity of patient variables, institutional experience, and physician specialty/training will be useful in informing clinical decision making for the ablative treatment of HCC or CRLM.

Laparoscopic microwave ablation versus percutaneous microwave ablation of hepatic malignancies: Efficacy and recurrence-free survival outcomes in patients

BACKGROUND

Hepatic thermal ablation has been found to be effective and equivalent to resection in certain liver histologies. Of the 16,000 annual liver ablations performed in the United States, only 13% (2,080 ablations) are performed laparoscopically. The laparoscopic technique remains underused even with the benefits of improved staging and better access to tumors. The purpose of this study is to compare laparoscopic microwave ablation versus percutaneous microwave ablation in terms of efficacy and recurrence-free survival outcomes in patients with hepatic malignancies.

METHODS

A comparative analysis was performed on 275 patients (289 ablation procedures) who underwent laparoscopic microwave ablation or percutaneous microwave ablation between February 2011 and May 2021. Ablation success was confirmed postprocedure and recurrence was monitored at follow-up via contrast-enhanced computed tomography/magnetic resonance imaging and/or computed tomography/positron emission tomography.

RESULTS

The groups were similar for sex, age, body mass index, location of tumor, size of tumor, and number of tumors. Ablation success was 100% in both groups. Local recurrence was significant (5%: laparoscopic microwave ablation vs 22%: percutaneous microwave ablation, P = .002) and same-lobe recurrence (21%: laparoscopic microwave ablation vs 24%: percutaneous microwave ablation) was lower in the laparoscopic microwave ablation group. Median recurrence-free survival was 15.8 months for the laparoscopic microwave ablation group and 5.6 months for the percutaneous microwave ablation group (P = .0002). Overall, 90-day complications were lower in the laparoscopic microwave ablation group (11%) compared with the percutaneous microwave ablation group (21%) (P = .11).

CONCLUSION

Laparoscopic surgical ablation is a critical surgical skill that must be taught in fellowship. Laparoscopic microwave ablation leads to better tumor specific outcomes and oncologic outcomes demonstrating clinical efficacy in the treatment of hepatic malignancies compared with percutaneous microwave ablation.

A meta-analysis and systematic review of the comparison of laparoscopic ablation to percutaneous ablation for hepatic malignancies

BACKGROUND

The optimal access for thermal ablation of the liver has not been evaluated in the literature for the laparoscopic versus percutaneous techniques. The aim of this manuscript was to determine the optimal ablation technique and patient selection for hepatic malignancies by comparing the efficacy and recurrence-free survival of laparoscopic and percutaneous thermal ablation.

METHODS

A detailed literature search was made in PubMed, Web of Science, Google scholar, and EMBASE for related research publications. The data were extracted and assessed by two reviewers independently. Analysis of pooled data was performed, and Odds Ratio (OR) or Hazard Ratio (HR) with corresponding confidence intervals (CIs) was calculated and summarized respectively.

RESULTS

A total of 10 articles were included with 1916 ablation patients. Laparoscopic ablation success (Median 100%) was found to be higher than percutaneous ablation success (median 89.4%) (p = ns). There was a higher percentage of both local and non-local hepatic recurrence in the patients treated with percutaneous ablation versus laparoscopic ablation. Meta-analysis indicated no difference in the adjusted hazard rate of recurrence by procedure type (p = 0.94). Laparoscopic ablation had a higher percentage of complications compared to percutaneous ablation (median lap 14.5% vs. perc 3.3%).

CONCLUSIONS

While laparoscopic and percutaneous ablation are both effective interventions for hepatic malignancies, laparoscopic ablation was found to have improved ablation success and less local and non-local hepatic recurrence compared to percutaneous ablation.

Colorectal Liver Metastases: A Literature Review of Viable Surgical Options with a Special Focus on Microwave Liver Thermal Ablation and Mini-Invasive Approach

Colorectal cancer (CRC) is the third most common tumor worldwide and it is characterized in 20-30% of cases by liver involvement, which strongly affects the long-term patient outcome. There are many available therapies for liver colorectal metastases (CRLMs); the current standard of care is represented by liver resection, and when feasible, associated with systemic chemotherapy. Microwave thermal ablation (MWA) is a viable option in unresectable patients or to achieve treatment with a parenchymal spearing approach. A literature review was performed for studies published between January 2000 and July 2022 through a database search using PUBMED/Medline and the Cochrane Collaboration Library with the following MeSH search terms and keywords: microwave, ablation, liver metastases, colorectal neoplasm, and colon liver rectal metastases. The recurrence rate and overall patients' survival were evaluated, showing that laparoscopic MWA is safe and effective to treat CRLMs when resection is not feasible, or a major hepatectomy in fragile patients is necessary. Considering the low morbidity of this procedure, it is a viable option to treat patients with recurrent diseases in the era of effective chemotherapy and multimodal treatments.

Feasibility and Safety of Single-Probe Cryoablation with Liquid Nitrogen: An Initial Experience in 24 Various Tumor Lesions

Simple Summary

Percutaneous cryoablation was developed to minimally perform multi-organ tumor ablations. The most widely known cryotherapy systems use argon gas (high-pressure) and multiple needles to achieve sufficient ablations. The aim of our retrospective study was to assess the feasibility of a new cryotherapy system using single-probe liquid nitrogen for tumor lesions of various sizes and locations, and to evaluate the safety of cryoablation with this technique. Correlations between ice ball sizes and ablation zone sizes with two needle sizes (10G or 13G) and with the freezing duration were evaluated, as well as the sphericity of the ice ball and ablation zones. We showed that this technique is safe in all organs tested. We showed a correlation between the freezing duration and the ice ball size, but not with the ablation zone, which is useful for planning the procedure and treatment conducted by the oncology team.

Abstract

Background: Percutaneous cryoablation with liquid nitrogen is a new technique being used in the treatment of some malignant tumors. Our objective was to assess its feasibility in the ablation of tumor lesions of various sizes and locations. Methods: This retrospective, monocentric study included all consecutive patients who underwent percutaneous cryoablation with liquid nitrogen between December 2019 and March 2021. Cryoablation was performed using 10G or 13G cryoprobes. The ablation volume was measured on post-treatment CT or MRI. Results: 22 patients (24 lesions) were included, 16 of whom were men (73%), while median age was 66 years. The lesions were located in the bone (42%), kidney (29%), soft tissue (17%), lung (8%), or liver (4%). It was feasible in all tumor locations and produced median ablation zones 25 mm in width and 35 mm in length, with a 23 min median freezing time. Freezing duration was correlated with the ice volume (p Spearman = 0.02), but not with the ablation volume (p = 0.11). The average difference between the ablation zone and ice ball sizes were −6.4 mm in width and −7.7 mm in length. Both ice and ablation volumes were larger when using the 10G probe as compared to when the 13G was used. No complications were reported. Discussion: We showed that this technique was safe and feasible in all organs tested. The freezing duration was correlated with the ice ball size, but not with the ablation zone.

Three-dimensional assessment of vascular cooling effects on hepatic microwave ablation in a standardized ex vivo model

The aim of this study was a three-dimensional analysis of vascular cooling effects on microwave ablation (MWA) in an ex vivo porcine model. A glass tube, placed in parallel to the microwave antenna at distances of 2.5, 5.0 and 10.0 mm (A-V distance), simulated a natural liver vessel. Seven flow rates (0, 1, 2, 5, 10, 100, 500 ml/min) were evaluated. Ablations were segmented into 2 mm slices for a 3D-reconstruction. A qualitative and quantitative analysis was performed. 126 experiments were carried out. Cooling effects occurred in all test series with flow rates ≥ 2 ml/min in the ablation periphery. These cooling effects had no impact on the total ablation volume (p > 0.05) but led to changes in ablation shape at A-V distances of 5.0 mm and 10.0 mm. Contrary, at a A-V distance of 2.5 mm only flow rates of ≥ 10 ml/min led to relevant cooling effects in the ablation centre. These cooling effects influenced the ablation shape, whereas the total ablation volume was reduced only at a maximal flow rate of 500 ml/min (p = 0.002). Relevant cooling effects exist in MWA. They mainly depend on the distance of the vessel to the ablation centre.

Evaluation method of ex vivo porcine liver reduced scattering coefficient during microwave ablation based on temperature

The principle of microwave ablation (MWA) is to cause irreversible damage (protein coagulation, necrosis, etc.) to tumor cells at a certain temperature by heating, thereby destroying the tumor. We have long used functional near-infrared spectroscopy (fNIRs) to monitor clinical thermal ablation efficacy. After a lot of experimental verification, it can be found that there is a clear correlation between the reduced scattering coefficient and the degree of tissue damage. During the MWA process, the reduced scattering coefficient has a stable change. Therefore, both temperature (T) and reduced scattering coefficient ( μ s ′ ${\mu }_{s}^{\prime }$ ) are related to the thermal damage of the tissue. This paper mainly studies the changing law of T and μ s ′ ${\mu }_{s}^{\prime }$ during MWA and establishes a relationship model. The two-parameter simultaneous acquisition system was designed and used to obtain the T and μ s ′ ${\mu }_{s}^{\prime }$ of the ex vivo porcine liver during MWA. The correlation model between T and μ s ′ ${\mu }_{s}^{\prime }$ is established, enabling the quantitative estimation of μ s ′ ${\mu }_{s}^{\prime }$ of porcine liver based on T. The maximum and the minimum relative errors of μ s ′ ${\mu }_{s}^{\prime }$ are 79.01 and 0.39%, respectively. Through the electromagnetic simulation of the temperature field during MWA, 2D and 3D fields of reduced scattering coefficient can also be obtained using this correlation model. This study contributes to realize the preoperative simulation of the optical parameter field of microwave ablation and provide 2D/3D therapeutic effect for clinic.

Temperature control and intermittent time-set protocol optimization for minimizing tissue carbonization in microwave ablation

PURPOSE

The charring tissue formation in the ablated lesion during the microwave ablation (MWA) of tumors would induce various unwanted inflammatory responses. This paper aimed to deliver appropriate thermal dose for effective ablations while preventing tissue carbonization by optimizing the treatment protocol during MWA with the set combinations of temperature control and pulsed microwave energy delivery.

MATERIAL AND METHODS

The thermal phase transition of ex vivo porcine liver tissues were recorded by differential scanning calorimetry (DSC) to determine the temperature threshold during microwave output control. MWA was performed by an in-house built system with the ease of microwave output parameter adjustment and real-time temperature monitoring. The effects of continuous and pulsed microwave deliveries as well as various intermittent time-set of MWA were evaluated by measuring the dimensions of the coagulation zone and the carbonization zone.

RESULTS

The DSC scans demonstrated that the ex vivo porcine liver tissues have been in a state of endothermic heat during the heating process, where the maximum absorbed heat occurred at the temperature of 105 °C ± 5 °C. The temperature control during MWA resulted in effective coagulative necrosis while preventing tissue carbonization, after setting 100 °C as the upper threshold temperature and 60 °C as the lower threshold. Both the numerical simulation and ex vivo experiments have shown that, upon the optimization of the time-set parameters in the periodic intermittent pulsed microwave output, the tissue carbonization was significantly diminished.

CONCLUSION

This study developed a straight-forward anti-carbonization strategy in MWA by modulating the pulsing mode and intermittent time. The programmed protocols of intermittent pulsing MWA have demonstrated its potentials toward future expansion of MWA technology in clinical application.

Microwave Ablation of Liver, Kidney and Lung Lesions: One-Month Response and Manufacturer’s Charts’ Reliability in Clinical Practice

Microwave ablation systems allow for performing tumoral destruction in oncology. The objective of this study was to assess the early response and reliability of the microwave ablation zone size at one month for liver, kidney and lung lesions, as compared to the manufacturer’s charts. Patients who underwent microwave ablation with the Emprint^TM ablation system for liver, kidney and lung lesions between June 2016 and June 2018 were retrospectively reviewed. Local response and ablation zone size (major, L, and minor, l, axes) were evaluated on the one-month follow-up imaging. Results were compared to the manufacturers’ charts using the Bland–Altman analysis. Fifty-five patients (mean age 68 ± 11 years; 95 lesions) were included. The one-month complete response was 94%. Liver ablations showed a good agreement with subtle, smaller ablation zones (L: −2 ± 5.7 mm; l: −5.2 ± 5.6 mm). Kidney ablations showed a moderate agreement with larger ablations for L (L: 8.69 ± 7.94 mm; l: 0.36 ± 4.77 mm). Lung ablations showed a moderate agreement, with smaller ablations for l (L: −5.45 ± 4.5 mm; l: −9.32 ± 4.72 mm). With 94% of early complete responses, the system showed reliable ablations for liver lesions, but larger ablations for kidney lesions, and smaller for lung lesions.

Multi-institutional analysis of outcomes for thermosphere microwave ablation treatment of colorectal liver metastases: the SMAC study

OBJECTIVES

Oligometastatic colorectal cancer benefits of locoregional treatments but data concerning microwave ablation (MWA) are limited and interactions with systemic therapy are still debated. The aim of this study is to evaluate safety and effectiveness of Thermosphere™ MWA (T-MWA) of colorectal liver metastases (CLM) and factors affecting local tumor progression-free survival (LTPFS).

METHODS

In this multi-institutional retrospective study (January 2015-September 2019), patients who underwent T-MWA for CLM were enrolled. Complications according to SIR classification were collected, primary efficacy and LTP were calculated. Analyzed variables included CLM size at diagnosis and at ablation, CLM number, ablation margins, intra-segment progression, chemotherapy before ablation (CBA), variations in size (ΔS_DIA-ABL), and velocity of size variation (V_DIA-ABL) between CLM diagnosis and ablation. Uni/multivariate analyses were performed using mixed effects Cox model to account for the hierarchical structure of data, patient/lesions.

RESULTS

One hundred thirty-two patients with 213 CLM were evaluated. Complications were reported in 6/150 procedures (4%); no biliary complications occurred. Primary efficacy was achieved in 204/213 CLM (95.7%). LTP occurred in 58/204 CLM (28.4%). Six-, twelve-, and eighteen-month LTPFS were 88.2%, 75.8%, and 69.9%, respectively. At multivariate analysis, CLM size at ablation (p = 0.00045), CLM number (p = 0.046), ablation margin < 5 mm (p = 0.0035), and intra-segment progression (p < 0.0001) were statistically significant for LTPFS. ΔS_DIA-ABL (p = 0.63) and V_DIA-ABL (p = 0.38) did not affect LTPFS. Ablation margins in the chemo-naïve group were larger than those in the CBA group (p < 0.0001).

CONCLUSION

T-MWA is a safe and effective technology with adequate LTPFS rates. Intra-segment progression is significantly linked to LTPFS. CBA does not affect LTPFS. Anticipating ablation before chemotherapy may take the advantages of adequate tumor size with correct ablation margin planning.

KEY POINTS

• Thermosphere™-Microwave ablation is a safe and effective treatment for colorectal liver metastases with no registered biliary complications in more than 200 ablations. • Metastases size at time of ablation, intra-segment progression, and minimal ablation margin < 5 mm were found statistically significant for local tumor progression-free survival. • Chemotherapy before ablation modifies kinetics growth of the lesions but deteriorates ablation margins and does not significantly impact local tumor progression-free survival.

Effective models of microwave antennae for ablation treatment planning

The level of detail of typical numerical models of microwave tumor ablations poses a challenge to the development of generic, model based treatment planning tools aiming at real time performance. The present contribution describes a flexible and accurate approximation of the microwave heat absorption that aims at mitigating these issues.

Microwave ablation for colorectal cancer metastasis to the liver: a single-center retrospective analysis

Background

The purpose of this study is to evaluate the safety and intermediate-term efficacy of percutaneous microwave (MW) ablation for the treatment of colorectal liver metastases (CRLM) at a single institution.

Methods

A retrospective review was performed of all CRLM treated with MW ablation from 3/2011 to 7/2020 (102 tumors; 72 procedures; 57 patients). Mean age was 60 years (range, 36-88) and mean tumor size was 1.8 cm (range, 0.5-5.0 cm). The patient population included 19 patients with extra-hepatic disease. Chemotherapy (pre- and/or post-ablation) was given in 98% of patients. Forty-five sessions were preceded by other focal CRLM treatments including resection, ablation, radiation, and radioembolization. Kaplan-Meier curves were used to estimate local tumor progression-free survival (LTPFS), disease-free survival (DFS), and overall survival (OS) and multivariate analysis (Cox Proportional Hazards model) was used to test predictors of OS.

Results

Technical success (complete ablation) was 100% and median follow-up was 42 months (range, 1-112). There was a 4% major complication rate and an overall complication rate of 8%. Local tumor progression (LTP) rate during the entire study period was 4/98 (4%), in which 2 were retreated with MW ablation for a secondary LTP-rate of 2%. LTP-free survival at 1, 3, and 5 years was 93%, 58%, and 39% and median LTP-free survival was 48 months. OS at 1, 3, and 5 years was 96%, 66%, 47% and median OS was 52 months. There were no statistically significant predictors of OS.

Conclusions

MW ablation of hepatic colorectal liver metastases appears safe with excellent local tumor control and prolonged survival compared to historical controls in selected patients. Further comparative studies with other local treatment strategies appear indicated.

Intrahepatic cholangiocarcinoma as the new field of implementation of laparoscopic liver resection programs. A comparative propensity score-based analysis of open and laparoscopic liver resections

BACKGROUND

The aim of the present study is to analyze the outcomes of laparoscopic and open liver resections for (Intrahepatic CholangioCarcinoma) ICC in the modern era of laparoscopic liver surgery.

METHODS

Patients undergoing laparoscopic and open liver resections for ICC in two European referral centers were included. Finally, 104 patients from the open group and 104 patients from the laparoscopic group were compared after propensity scores matching according to seven covariates representative of patients and disease characteristics. Indications to surgery and short- and long-term outcomes were compared.

RESULTS

Operative time, number of retrieved nodes, rate, and depth of negative resection margins were comparable between the two groups. Blood loss was lower in the MILS (150 ± 100 mL, mean ± SD) compared with the Open group (350 ± 250 mL, p = 0.030). Postoperative complications occurred in 14.4% of patients in the MILS and in the 24% of patients in the Open group (p = 0.02). There were no significant differences in long-term outcomes between groups.

CONCLUSIONS

Our results confirm feasibility, safety, and oncological efficiency of the laparoscopic approach in the management of ICC. However, this surgery is often complex and should be only considered in centers with large experience in laparoscopic liver surgery.

Evolution of Surgical Treatment of Colorectal Liver Metastases in the Real World: Single Center Experience in 1212 Cases

BACKGROUND

In recent years, the treatment of colorectal liver metastases (CRLM) has undergone significant evolution thanks to technical improvements as well as oncological advances, which have been the subject of targeted studies aimed at understanding the details of this heterogeneous disease. The purpose of this study is to put together pieces of this complex scenario by providing an overview of the evolution that has occurred in the context of a single center within a multidisciplinary management approach.

METHODS

Between 2005 and 2020, 1212 resections for CRLM were performed at the Hepatobiliary Surgery Division of San Raffaele Hospital, Milan. The series was divided into three historical periods, which were compared in terms of disease characteristics and short- and long-term outcomes: Period 1, 2005-2009 (293 cases); Period 2, 2010-2014 (353 cases); Period 3, 2015-2020 (566 cases). The trends for surgical technical complexity, oncological burden of the disease, use of the laparoscopic approach and use of techniques for hepatic hypertrophy were analyzed year by year. Uni- and multivariate analyses were performed to identify factors associated with inclusion to a laparoscopic approach and with long-term prognosis.

RESULTS

The number of resections performed over the years progressively increased, with an increase in the number of cases with a high Clinical Risk Score and a high profile of technical complexity. The proportion of cases performed laparoscopically increased, but less rapidly compared to other malignant tumors. The risk of postoperative morbidity and mortality was similar in the three analyzed periods. Long-term survival, stratified by Clinical Risk Score, improved in Period 3, while overall survival remained unchanged.

CONCLUSION

The cultural background, the maturation of technical expertise and the consolidation of the multidisciplinary team have resulted in safe expansion of the possibility to offer a curative opportunity to patients, while continuously implementing into clinical practice evidence provided by the literature.

Percutaneous microwave ablation applications for liver tumors: recommendations for COVID-19 patients

Microwave ablation (MWA) is an alternative locoregional therapy to surgical resection of solid tumors in the treatment of malignancies, and is widely used for hepatic tumors. It has a slightly higher overall survival (OS) rate compared to external beam radiation therapy (EBRT), and proton beam therapy (PBT), and better long-term recurrence-free OS rate compared to radiofrequency ablation (RFA). In this paper, current commercial devices, most recent noncommercial designs, and the principles behind them alongside the recently reported developments and issues of MWA are reviewed. The paper also provides microscopic insights on effects of microwave irradiation in the body. Our review shows that MWA is a safe and effective, minimally invasive method with high ablation completion rates. However, for large tumors, the completion rates slightly decrease, and recurrences increase. Thus, for large tumors we suggest using a cooled shaft antenna or multiple antenna placements. Comparisons of the two common ablation frequencies 915 MHz and 2.45 GHz have shown inconsistent results due to non-identical conditions. This review suggests that 915 MHz devices are more effective for ablating large tumors and the theory behind MWA effects corroborates this proposition. However, for small tumors or tumors adjacent to vital organs, 2.45 GHz is suggested due to its more localized ablation zone. Among the antenna designs, the double-slot antenna with a metallic choke seems to be more effective by localizing the radiation around the tip of the antenna, while also preventing backward radiation towards the skin. The review also pertains to the use of MWA in COVID-19 patients and risk factors associated with the disease. MWA should be considered for COVID-19 patients with hepatic tumors as a fast treatment with a short recovery time. As liver injury is also a risk due to COVID-19, it is recommended to apply liver function tests to monitor abnormal levels in alanine aminotransferase (ALT), aspartate aminotransferase (AST), total bilirubin, and other liver function indicators.

Microwave Thermoablation of Colorectal Liver Metastases Close to Large Hepatic Vessels Under Pringle Maneuver Minimizes the "Heat Sink Effect"

BACKGROUND

Liver resection and thermoablation are the mainstay of the surgical management of colorectal liver metastases (CRLM). The main limitation of thermoablation is the "heat-sink" effect for nodules next to large vessels. Herein, we report the preliminary results of microwave ablation (MWA) with associated Pringle maneuver to overcome this flaw.

METHODS

From November 2017, we performed intraoperative MWA with Pringle maneuver for nodules ≤3 cm with immediate proximity to large vessels (distance ≤ 5 mm, diameter ≥ 3 mm). We collected characteristics of nodules, surgical procedures and postoperative morbidity. Diameter of the ablation area, especially the ablative minimal margin, was calculated for each nodule. Recurrence was also evaluated.

RESULTS

Nineteen patients underwent MWA with Pringle maneuver for 23 nodules. Nineteen (83%) ablated nodules were located in segments VI, VII and VIII, and one nodule was in segment I. Median size of nodules was 15 mm (10-21). No deaths occurred. Six patients (38%) experienced complications, among them only one was subsequent to the thermal ablation. Ablative minimal margin was ≥5 mm for 19 (83%) nodules. Margin was not sufficient for four nodules, among them only 2/23 cases (8.7%) of in situ recurrence occurred after 12 months of median follow-up.

CONCLUSIONS

In this preliminary study, MWA with Pringle maneuver was associated with a low related morbidity rate and favorable oncological outcome, especially when the radiological minimal margin was sufficient.

Immediate post-interventional contrast-enhanced computed tomography overestimates hepatic microwave ablation - an in vivo animal study

Objectives: Contrast-enhanced computed tomography (CECT) is used to monitor technical success immediately after hepatic microwave ablation (MWA). However, it remains unclear, if CECT shows the exact extend of the thermal destruction zone, or if tissue changes such as peri-lesionary edema are depicted as well. The objective of this study was to correlate immediate post-interventional CECT with histological and macroscopic findings in hepatic MWA in porcine liver in vivo.Methods: Eleven MWA were performed in porcine liver in vivo with a microwave generator (928 MHz; energy input 24 kJ). CECT was performed post-interventionally. Livers were explanted and ablations were bisected immediately after ablation. Samples were histologically analyzed after vital staining (NADH-diaphorase). Ablation zones were histologically and macroscopically outlined. We correlated histologic findings, macroscopic images and CECT.Results: Three ablation zones were identified in histological and macroscopic findings. Only one ablation zone could be depicted in CECT. Close conformity was observed between histological and macroscopic findings. The ablation zone depicted in CECT overestimated the histological avital central zone and inner red zone (p < = .01). No differences were found between CECT and the histological outer red zone (p > .05).Conclusions: Immediate post-interventional CECT overestimated the clinically relevant zone of complete cell ablation after MWA in porcine liver in vivo. This entails the risk of incomplete tumor ablation and could lead to tumor recurrence.

Preablation three-dimensional ultrasonography can predict therapeutic effect and local tumor progression after radiofrequency ablation for hepatocellular carcinoma

PURPOSE

To assess the agreement between ablative margin (AM) predicted by preablation three-dimensional ultrasonography (3D-US) and AM measured on postablation computed tomography (CT)/magnetic resonance (MR) images.

METHODS

Sixty patients with 73 hepatocellular carcinoma nodules were enrolled. 3D-US data were collected immediately after puncture by the electrode before ablation. The maximum distance from the electrode to the edge of the tumor in the plane perpendicular to the electrode (C-plane) was defined as "a" and the diameter of the ablation zone as "b". We classified predicted AM into "0.5b - a" ≥0 mm as AM(+) or <0 mm as AM(-), and "0.5b - a" ≥3 mm or <3 mm.

RESULTS

Forty-eight nodules (66 %) were visualized in the C-plane. There was an agreement between the predicted and measured AMs for 39 (81 %) of the 48 nodules. Local tumor progression was observed in 3 (7%) of 43 nodules with predicted AM(+) and in 2 (40 %) of 5 nodules with predicted AM(-) but was not observed in any of 21 nodules with predicted AM ≥ 3 mm. The local tumor progression rate was significantly lower for nodules with predicted AM(+) compared with predicted AM(-)(p = 0.03), and for nodules with predicted AM ≥ 3 mm compared with predicted AM < 3 mm (p = 0.04). Local progression was detected in 2 (4.7 %) of 42 nodules with a sufficient AM (≥0 mm) on postablation CT/MR images and in 5 (83.3 %) of 6 nodules with an insufficient AM (<0 mm); the difference in progression rate was significant (p = 0.0008).

CONCLUSION

3D-US allows prediction of the AM before radiofrequency ablation.

A pre-operative platelet transfusion algorithm for patients with cirrhosis and hepatocellular carcinoma undergoing laparoscopic microwave ablation

BACKGROUND

Thrombocytopenia is a common finding in patients with chronic liver disease. It is associated with poor clinical outcomes due to increased risk of bleeding after even minor procedures. We sought to determine an algorithm for pre-operative platelet transfusion in patients with cirrhosis and hepatocellular carcinoma (HCC) undergoing laparoscopic microwave ablation (MIS-MWA).

METHODS

A retrospective review identified all patients with cirrhosis and HCC who underwent MIS-MWA at a single tertiary institution between 2007 and 2019. Demographics, pre-operative and post-operative laboratory values, transfusion requirements, and bleeding events were collected. The analyzed outcome of bleeding risk included any transfusion received intra-operatively or a transfusion or surgical intervention post-operatively. Logistic regression models were created to predict bleeding risk and identify patients who would benefit from pre-operative transfusion.

RESULTS

There were 433 patients with cirrhosis and HCC who underwent MIS-MWA identified; of these, 353 patients had complete laboratory values and were included. Bleeding risk was evaluated through bivariate analysis of statistically and clinically significant variables. The accuracy of both models was substantiated through bootstrap validation for 500 iterations (model 1: ROC 0.8684, Brier score 0.0238; model 2: ROC 0.8363, Brier score 0.0252). The first model captured patients with both thrombocytopenia and anemia: platelet count < 60 × 10⁹ / L (OR 7.75, p 0.012, CI 1.58-38.06) and hemoglobin < 10 gm/dL (OR 5.76, p 0.032, CI 1.16-28.63). The second model captured patients with thrombocytopenia without anemia: platelet count < 30 × 10⁹/L (OR 8.41, p 0.05, CI 0.96-73.50) and hemoglobin > 10 gm/dL (OR 0.16, p 0.026, CI 0.031-0.80).

CONCLUSION

The prediction of patients with cirrhosis and HCC requiring pre-operative platelet transfusions may help to avoid bleeding complications after invasive procedures. This study needs to be prospectively validated and ultimately may be beneficial in assessment of novel therapies for platelet-based clinical treatment in liver disease.

Study on the relationship between reduced scattering coefficient and Young's modulus of tumors in microwave ablation

BACKGROUND AND OBJECTIVE

In the clinical treatment of tumors using microwave ablation (MWA), although temperature can be used as an important reference index for evaluating the curative effect of ablation, it cannot fully reflect the biological activity status of tumor tissue during thermal ablation. Finding multi-parameter comprehensive evaluation factors to achieve real-time evaluation of therapeutic effects has become the key for precise ablation. More and more scholars use the reduced scattering coefficient (μs') and Young's modulus (E) to evaluate the treatment outcomes of MWA. However, the intrinsic relationship between these parameters is unclear. This paper aims to investigate the specific relationship between μs' and E during MWA.

MATERIAL AND METHODS

The MWA experiment was conducted on porcine liver in vitro, the two-parameter simultaneous acquisition system was designed to obtain the reduced scattering coefficient and Young's modulus of the liver tissue during MWA. The relationship between reduced scattering coefficient and Young's modulus was investigated.

RESULTS

It is found that the trend of change of μs' is very similar to E in the process of MWA, i.e. first increasing and then reaching a steady state, and in some experiments there are synchronous changes. Based on this, the quantitative relationship between E-μs'  is established, enabling the quantitative estimation of Young's modulus of liver tissue based on reduced scattering coefficient. The maximum absolute error is 29.37 kPa and the minimum absolute error is 0.88 kPa.

CONCLUSION

This study contributes to the further establishment of a multi-parameter MWA effectiveness evaluation model. It is also valuable for clinically evaluating the ablation outcomes of tumor in real time.

Reappraisal of the advantages of laparoscopic liver resection for intermediate hepatocellular carcinoma within a stage migration perspective: Propensity score analysis of the differential benefit

OBJECTIVE

The aim of the present study was to analyze the outcome of laparoscopic approach specifically in patients with Intermediate-stage disease and to define the differential benefit with Early-stage patients.

METHODS

Six hundred twenty-two resections for HCC were dichotomized according to staging (Early and Intermediate) and to approach and then matched in a 1:1 ratio using propensity scores to obtain four groups (E-MILS and E-Open, including 104 patients respectively; Int-MILS and Int-Open, including 142 patients, respectively). The differential benefit associated with the minimally invasive technique was evaluated between intermediate-stage and early-stage patients taking into account blood loss and morbidity rate as outcome indicators.

RESULTS

Laparoscopic approach resulted in a statistically significant lower blood loss, reduced morbidity, reduced incidence of hepatic decompensation and shorter time for functional recover and length of stay. The evaluation of the differential benefit showed a greater advantage of laparoscopic approach in Intermediate-stage patients compared with Early-stage patients, both in terms of blood loss and morbidity rate.

CONCLUSIONS

The favorable biological scenario associated with laparoscopic approach allows to obtain enhanced benefits in the setting of more advanced liver disease. The push towards minimal invasiveness and the incremental benefit associated with it could potentially promote stage migration in suitable patients.

Salvage treatment of NSCLC recurrence after first-line chemotherapy failure: Iodine-125 seed brachytherapy or microwave ablation?

Background

Salvage treatments for recurrent NSCLC after first‐line chemotherapy remain challenging. This study was conducted to evaluate the clinical value of microwave ablation (MWA) and iodine‐125 brachytherapy, including overall survival (OS), disease free survival (DFS), local control, hospital stay, and health economics.

Methods

The data of 51 and 32 patients who were treated with MWA and brachytherapy was retrospectively analyzed. The number of lesions was limited up to two, with a diameter <4 cm and patients diagnosed with unilateral lung disease. Peripheral tumors were treated with MWA, while lesions close to the hilum were treated with brachytherapy. Contrast‐enhanced CT, blood cell count, coagulation function, liver & kidney function and tumor markers were performed for two years, with complications calculated. OS, DFS, local control rate, toxicity, hospital stay and expense were recorded.

Results

The one and two‐year OS rates were 96.08% and 92.16% versus 96.88% and 90.62% in the MWA and brachytherapy groups, respectively. The one and two‐year DFS rates were 92.16% and 76.47% versus 93.75% and 78.13%, respectively. No significant differences were observed in log‐rank analysis between the groups. Local control rates at six and 12 months were 100% and 96.08% versus 100% and 96.88%, while incidences of pleural effusion were 3.92% and 3.13%, respectively (P < 0.05). Medical cost was 3356.73 ± 206.87 and 6714.28 ± 35.43 U.S. dollars (P = 0.014).

Conclusion

MWA and brachytherapy are effective and safe options for the treatment of NSCLC recurrence after first‐line chemotherapy. Which modality should be considered is dependent upon tumor location, tumor size and experience of specialists.

A review of conventional and newer generation microwave ablation systems for hepatocellular carcinoma

Although microwave ablation (MWA) exhibits a high thermal efficiency, the major limitation of conventional MWA systems is the lack of predictability of the ablation zone size and shape. Therefore, a specific newer generation MWA system, The Emprint™ Ablation System with Thermosphere™ Technology, was designed to create predictable large spherical zones of ablation that are not impacted by varying tissue environments. The time required for ablation with MWA systems is short, and the shape of the necrosis is elliptical with the older systems and spherical with the new system. In addition, because MWA has no heat-sink effect, it can be used to ablate tumors adjacent to major vessels. Although these factors yield a large ablation volume and result in good local control, excessive ablation of liver tissue and unexpected ablation of surrounding organs are possible. Therefore, MWA should be carefully performed. This review highlights the efficacy and complications of MWA performed with conventional systems and the newer generation system in patients with hepatocellular carcinoma (HCC). MWA with the newer generation system seems to be a promising treatment option for large HCCs and secondary hepatic malignancies, with several advantages over other available ablation techniques, including conventional MWA. However, further randomized controlled trials are necessary to fully clarify the benefits and pitfalls of this new system.

3D visualization ablation planning system assisted microwave ablation for hepatocellular carcinoma (Diameter >3): a precise clinical application

Background

The aim of this retrospective study was to compare the feasibility and efficiency of ultrasound-guided percutaneous microwave ablation (US-PMWA) assisted by three-dimensional visualization ablation planning system (3DVAPS) and conventional 2D planning for hepatocellular carcinoma (HCC) (diameter > 3 cm).

Methods

One hundred thirty patients with 223 HCC nodules (5.0 ± 1.5 cm in diameter, [3.0–10.0 cm]) who met the eligibility criteria divided into 3D and 2D planning group were reviewed from April 2015 to August 2018. Ablation parameters and oncological outcomes were compared, including overall survival (OS), recurrence-free survival (RFS), and local tumor progression (LTP). Multivariate analysis was performed on clinicopathological variables to identify the risk factors for OS and LTP.

Results

The median follow-up period was 21 months (range 3–44). Insertion number (5.4 ± 1.2 VS. 4.5 ± 0.9, P = 0.034), ablation time (1249.2 ± 654.2 s VS. 1082.4 ± 584.7 s, P = 0.048), ablation energy (57,000 ± 11,892 J VS. 42,600 ± 10,271 J, P = 0.038) and success rate of first ablation (95.0% VS. 85.7%, P = 0.033) were higher in the 3D planning group compared with those in 2D planning group. There was no statistical difference in OS, and RFS between the two groups (P = 0.995, P = 0.845). LTP rate of 3D planning group was less than that of 2D planning group (16.5% VS 41.2%, P = 0.003). Multivariate analysis showed tumor maximal diameters (P < 0.001), tumor number (P = 0.003) and preoperative TACE (P < 0.001) were predictors for OS and sessions (P = 0.024), a-fetoprotein level (P = 0.004), and preoperative planning (P = 0.002) were predictors for LTP, respectively.

Conclusions

3DVAPS improves precision of US guided ablation resulting in lower LTP and higher 5 mm-AM for patients with HCC lesions larger than 3 cm in diameter.

Application of new ultrasound techniques for focal liver lesions

Ultrasonography (US) has the overwhelming advantages of not entailing radiation exposure and being a noninvasive, real-time, convenient, easy-to-perform, and relatively inexpensive imaging modality. It is used as the first-line imaging modality for screening, detection, and diagnosis of focal liver lesions (FLLs) [small hepatocellular carcinomas (HCCs), in particular]. However, with the increasing demand for accurate and early diagnosis of small HCCs, newer radiologic methods need to be explored to overcome certain limitations of US. For example, the imaging is easily negatively affected by the presence of gas, rib cage, and subcutaneous fat, and is insensitive for capturing the subtle but vital information on the blood flow. It was in response to this need that new promising technologies such as contrast-enhanced ultrasound and fusion imaging were introduced for the detection of liver lesions. This paper presents an overview of the epidemiology and mechanisms of the development of HCCs, with an emphasis on the application of US in the diagnosis and treatment of FLLs. The aim of this article is to provide the state-of-the-art developments in the imaging diagnosis of FLLs and evaluation of ablation treatment of early HCCs. By keeping abreast of these recent advances, we hope that doctors and researchers working in the field of diagnosis/treatment of liver diseases will be able to discriminate benign FLLs such as regenerative nodules and focal nodular hyperplasia from HCCs, so as to avoid unnecessary repeated tumor biopsies and overtreatment. In particular, we expect that small HCCs or precancerous nodules (such as dysplastic nodules) can be accurately diagnosed and appropriately treated even at an early stage.

Conformal coverage of liver tumors by the thermal coagulation zone in 2450-MHz microwave ablation

Purpose: To optimize treatment schemes using 2450-MHz microwave ablation (MWA), a novel conformal coverage method based on bipolar-angle mapping is proposed that determines whether a liver tumor is completely encompassed by thermal coagulation zones. Materials and methods: Firstly, three-dimensional (3-D) triangular mesh data of liver tumors were reconstructed from clinical computed tomography (CT) slices using the Marching cubes (MC) algorithm. Secondly, characterization models of thermal coagulation zones were established based on finite element simulation results of 40, 45, 50, 55, and 60 W ablations. Finally, coagulation zone models and tumor surface data were mapped and fused on a two-dimensional (2-D) plane to achieve conformal coverage of liver tumors by comparing the corresponding polar radii. Results: Optimal parameters for ablation treatment of liver tumors were efficiently obtained with the proposed conformal coverage method. Fifteen liver tumors were obtained with maximal diameters of 12.329-78.612 mm (mean ± standard deviation, 39.094 ± 19.447 mm). The insertion positions and orientations of the MWA antenna were determined based on 3-D reconstruction results of these tumors. The ablation patterns and durations of tumors were planned according to the minimum mean standard deviations between the ablative margin and tumor surface. Conclusion: The proposed method can be applied to computer-assisted MWA treatment planning of liver tumors, and is expected to guide clinical procedures in future.

Use of percutaneous microwave ablation for the treatment of bone tumors: a retrospective study of clinical outcomes in 47 patients

Objective

The present study aimed to evaluate the short-term clinical performance and safety of percutaneous microwave ablation (MWA) techniques for the treatment of bone tumors.

Methods

This single-institution retrospective study investigated 47 cases of bone tumors treated by MWA from June 2015 to June 2018. The study included 26 patients (55.3%) with benign bone tumors and 21 patients (44.7%) with malignant bone tumors. The tumors were located in the spine or sacrum (15, 31.9%), the upper extremities (6, 12.8%), the lower extremities (17, 36.2%) and the pelvis (9, 19.1%). Outcomes regarding clinical efficacy, including pain relief, quality of life, and intervention-related complications, were evaluated before and after MWA using the visual analog scale (VAS) and the 36-item Short-Form Health Survey (SF-36) scoring system.

Results

Of the 47 patients included in this study, all of them completed follow-up examinations, with a mean follow-up duration of 4.8 ± 1.6 months (range, 2–9 months). Significantly improved VAS and SF-36 scores were recorded after the initial treatment (P<0.001), suggesting that almost 100% of patients experienced pain relief and an improved quality of life following surgery. No major intervention-related complications (e.g., serious neurovascular injury or infection) occurred during or after the treatment. We recorded only three minor posttreatment complications (6.4%, 3/47), which were related to thermal injury that caused myofasciitis and affected wound healing.

Conclusion

In our study, the short-term efficacy of MWA was considerably favorable, with a relatively low rate of complications. Our results also showed that MWA was effective for pain relief and improved patients’ quality of life, making it a feasible treatment alternative for bone tumors.

Surgical management of metastatic gastric cancer: moving beyond the guidelines

Despite decreasing incidence, gastric cancer remains a major health problem worldwide and is associated with poor survival. The poor survival is mainly attributed to delayed presentation which may cause local or systemic metastases. The standard of care for patients with metastatic gastric cancer (MGC) is palliative chemotherapy with best supportive care. Although the survival has improved owing to advances in chemotherapeutic agents, it is still unsatisfactory, and some perspective changes are needed in the management of MGC to improve the outcomes. Therefore, various alternative treatment strategies for MGC have formed the most important research topics. Liver-directed treatment (LDT) options such as liver resection, radiofrequency ablation (RFA), microwave ablation (MWA), and hepatic artery infusion chemotherapy (HAIC) have been studied in the management of liver metastasis from gastric cancer (LMGC). Intraperitoneal chemotherapy (IPC) in addition to cytoreductive surgery (CRS) aiming to remove all macroscopic tumor focus resulting from peritoneal dissemination is the treatment option for peritoneal metastasis, while para-aortic lymph node dissection is the treatment option for para-aortic lymph node metastasis which is considered to be M1 disease. Conversion surgery is a novel concept aiming at R0 resection for originally unresectable or marginally resectable tumors after a remarkably good response to the chemotherapy. Large amounts of data in the literature have demonstrated the benefits of individualized approaches such as the combination of systemic and local treatment options in selected patient groups. In this review, we aimed to explore the current and future treatment options by reviewing the literature on this controversial topic.

Moderate Heat Application Enhances the Efficacy of Nanosecond Pulse Stimulation for the Treatment of Squamous Cell Carcinoma

Nanosecond pulse stimulation as a tumor ablation therapy has been studied for the treatment of various carcinomas in animal models and has shown a significant survival benefit. In the current study, we found that moderate heating at 43°C for 2 minutes significantly enhanced in vitro nanosecond pulse stimulation-induced cell death of KLN205 murine squamous cell carcinoma cells by 2.43-fold at 600 V and by 2.32-fold at 900 V, as evidenced by propidium iodide uptake. Furthermore, the ablation zone in KLN205 cells placed in a 3-dimensional cell-culture model and pulsed at a voltage of 900 V at 43°C was 3 times larger than in cells exposed to nanosecond pulse stimulation at room temperature. Application of moderate heating alone did not cause cell death. A nanosecond pulse stimulation electrode with integrated controllable laser heating was developed to treat murine ectopic squamous cell carcinoma. With this innovative system, we were able to quickly heat and maintain the temperature of the target tumor at 43°C during nanosecond pulse stimulation. Nanosecond pulse stimulation with moderate heating was shown to significantly extend overall survival, delay tumor growth, and achieve a high rate of complete tumor regression. Moderate heating extended survival nearly 3-fold where median overall survival was 22 days for 9.8 kV without moderate heating and over 63 days for tumors pulsed with 600, 100 ns pulses at 5 Hz, at voltage of 9.8 kV with moderate heating. Median overall survival in the control groups was 24 and 31 days for mice with untreated tumors and tumors receiving moderate heat alone, respectively. Nearly 69% (11 of 16) of tumor-bearing mice treated with nanosecond pulse stimulation with moderate heating were tumor free at the completion of the study, whereas complete tumor regression was not observed in the control groups and in 9.8 kV without moderate heating. These results suggest moderate heating can reduce the necessary applied voltage for tumor ablation with nanosecond pulse stimulation.

New microwave ablation system for unresectable liver tumors that forms large, spherical ablation zones

BACKGROUND AND AIM

The aim of this study was to assess the efficacy of a new microwave ablation (MWA) system, the Emprint Ablation System, for the ablation of unresectable large liver tumors (≥ 30 mm).

METHODS

Twenty-one hepatic tumors (mean diameter, 34.7 mm) from 21 patients who underwent percutaneous MWA were included in this cross-sectional study. A volume analyzer based on computed tomography imaging was used for all patients within the month before and month after the procedure to evaluate the shape and volume of ablation zones. In addition, computed tomography imaging was performed again 3 months after the procedure to evaluate the presence of residual tumors and local recurrence.

RESULTS

Mean ablation time was 11.3 min, and mean overall procedure time was 33.4 min. An ablated adrenal gland-induced Takotsubo (stress) cardiomyopathy occurred immediately after MWA as a major complication in one patient. Roundness index A, B, and C presented a mean value of 0.94, 0.94, and 1.01, respectively (all values near 1 is a perfect sphere), indicating that a spherical ablation zone was achieved. The mean ablation volume was larger than the volume of tumors (24.5 vs 41.7 cm³ ). Residual tumors were confirmed in only 4.8% of tumors after a single ablation session. There was no local recurrence.

CONCLUSIONS

In our experience, the new MWA system provides an effective treatment option for unresectable large liver tumors. However, to ablate the liver tumors safely, it is necessary to consider the surrounding organs, such as the adrenal glands.

Ablation Planning Software for Optimizing Treatment: Challenges, Techniques, and Applications

Percutaneous ablation can deliver effective anticancer therapy with minimal side effects; however, undertreatment can lead to disease recurrence and overtreatment can lead to unnecessary complications. Ablation planning software can support the procedure during the planning, treatment, and follow-up phases. In this review, 2 examples of microwave ablation software are described with attention to how the software can influence procedural choices. In the future, ablation software will entail larger source datasets and more refined algorithms to better model the in vivo ablation zone. Moreover, ablation simulation has the potential to augment clinical care beyond the interventional suite, such as procedural demonstration for patients, clinical consultation with referring providers, documentation for the medical record, and educational simulation for trainees.

RFA Guardian: Comprehensive Simulation of Radiofrequency Ablation Treatment of Liver Tumors

The RFA Guardian is a comprehensive application for high-performance patient-specific simulation of radiofrequency ablation of liver tumors. We address a wide range of usage scenarios. These include pre-interventional planning, sampling of the parameter space for uncertainty estimation, treatment evaluation and, in the worst case, failure analysis. The RFA Guardian is the first of its kind that exhibits sufficient performance for simulating treatment outcomes during the intervention. We achieve this by combining a large number of high-performance image processing, biomechanical simulation and visualization techniques into a generalized technical workflow. Further, we wrap the feature set into a single, integrated application, which exploits all available resources of standard consumer hardware, including massively parallel computing on graphics processing units. This allows us to predict or reproduce treatment outcomes on a single personal computer with high computational performance and high accuracy. The resulting low demand for infrastructure enables easy and cost-efficient integration into the clinical routine. We present a number of evaluation cases from the clinical practice where users performed the whole technical workflow from patient-specific modeling to final validation and highlight the opportunities arising from our fast, accurate prediction techniques.

Ultrasound-guided percutaneous microwave ablation vs. surgical resection for thoracoabdominal wall implants from hepatocellular carcinoma: intermediate-term results

OBJECTIVE

The aims of this study were to compare the clinical outcomes between ultrasound (US)-guided percutaneous microwave ablation (MWA) and surgical resection (SR) in patients with thoracoabdominal wall implants from hepatocellular carcinom (HCC) and to identify the prognostic factors associated with the two treatment methods.

MATERIALS AND METHODS

A total of 47 patients (mean age, 56.7 ± 15.9 years, range, 18-78 years; 34 men and 13 women) with 61 thoracoabdominal wall HCC seeding were included from April 2007 to May 2017. Twenty-five patients underwent US-guided MWA and 22 patients underwent SR. Survival, recurrence and liver function were compared between the two groups. Effect of changes in key parameters (i.e. overall survival (OS), disease-free survival (DFS) and local tumour reoccurrence-free (LTRF)) was statistically analysed with the log-rank test. Univariate and multivariate analyses were performed on several clinicopathological variables to identify factors affecting long-term outcome and recurrence.

RESULTS

The OS, DFS and LTRF after MWA were comparable to those of SR (p =0.493, p = 0.578 and p =0.270, respectively). Estimated 5-year overall survival rates were 63% after MWA and 48.1% after SR; for disease-free survival, estimated 5-year rates were 67.5% after MWA and 48.8% after SR; estimated 24-month LTRF rates were 71.3% after MWA and 87.8% after SR. The MWA group had less surgical time (p = <0.001), estimated blood loss (p = <0.001) and post-operative hospitalisation (p = 0.032) and cost (p = 0.015). Multivariate analysis showed remnant intrahepatic tumour (p =0.007), Child Pugh grade (p = 0.009) and metastasis (p= <0.001), were predictors for survival rate.

CONCLUSIONS

Ultrasound-guided percutaneous MWA is a safe and effective treatment method for metastatic HCC on the thoracoabdominal wall with similar outcomes to SR. Residual intrahepatic HCC, Child Pugh grade and distant metastasis are predictors for survival.