Stereotactically navigated percutaneous microwave ablation (MWA) compared to conventional MWA: a matched pair analysis

Feasibility of stereotactic optical navigation for needle positioning in percutaneous nephrolithotomy

BACKGROUND

This study assessed the feasibility of acquiring single-attempt access to the pelvicalyceal system during percutaneous nephrolithotomy (PCNL) using stereotactic optical navigation combined with cone-beam CT (CBCT) imaging.

METHODS

Patients with a PCNL indication were prospectively included in this IRB approved study. After sterile preparation, fiducial markers were attached to patients' skin. An initial intraprocedural CBCT scan was acquired, on which the urologist planned the needle trajectory using the navigation software. After verifying that no critical structures were crossed, the needle guide was aligned with the plan. A needle was manually inserted through the needle guide to the indicated depth and a second CBCT scan was performed for needle position confirmation. Both, scanning and needle insertion, were performed under apnea. The study evaluated technical success, accuracy, procedure time, complication rate, and radiation dose.

RESULTS

Between June 2022 and April 2023, seven patients were included. In all patients, the navigation system allowed safe puncture. However, the technical success rate was only 29%. In 42% of the cases, pelvicalyceal access was achieved by a small manual adjustment. In the remaining 29%, the needle was retracted and positioned per clinical standard. The average deviation between the needle and target was 5.9 ± 2.3 mm. The average total procedure time was 211 ± 44 min. The average radiation exposure was 6.4 mSv, with CBCT scanning contributing to 82% of this exposure.

CONCLUSIONS

The optical navigation system facilitated safe needle insertion but did not consistently ensure accurate one-attempt needle positioning for PCNL. Real-time visualization and trajectory correction may improve the technical success rate.

Ablation margin quantification after thermal ablation of malignant liver tumors: How to optimize the procedure? A systematic review of the available evidence

Introduction

To minimize the risk of local tumor progression after thermal ablation of liver malignancies, complete tumor ablation with sufficient ablation margins is a prerequisite. This has resulted in ablation margin quantification to become a rapidly evolving field. The aim of this systematic review is to give an overview of the available literature with respect to clinical studies and technical aspects potentially influencing the interpretation and evaluation of ablation margins.

Methods

The Medline database was reviewed for studies on radiofrequency and microwave ablation of liver cancer, ablation margins, image processing and tissue shrinkage. Studies included in this systematic review were analyzed for qualitative and quantitative assessment methods of ablation margins, segmentation and co-registration methods, and the potential influence of tissue shrinkage occurring during thermal ablation.

Results

75 articles were included of which 58 were clinical studies. In most clinical studies the aimed minimal ablation margin (MAM) was ≥ 5 mm. In 10/31 studies, MAM quantification was performed in 3D rather than in three orthogonal image planes. Segmentations were performed either semi-automatically or manually. Rigid and non-rigid co-registration algorithms were used about as often. Tissue shrinkage rates ranged from 7% to 74%.

Conclusions

There is a high variability in ablation margin quantification methods. Prospectively obtained data and a validated robust workflow are needed to better understand the clinical value. Interpretation of quantified ablation margins may be influenced by tissue shrinkage, as this may cause underestimation.

Ablative and non-surgical therapies for early and very early hepatocellular carcinoma: a systematic review and network meta-analysis

Background

A wide range of ablative and non-surgical therapies are available for treating small hepatocellular carcinoma in patients with very early or early-stage disease and preserved liver function.

Objective

To review and compare the effectiveness of all current ablative and non-surgical therapies for patients with small hepatocellular carcinoma (≤ 3 cm).

Design

Systematic review and network meta-analysis.

Data sources

Nine databases (March 2021), two trial registries (April 2021) and reference lists of relevant systematic reviews.

Review methods

Eligible studies were randomised controlled trials of ablative and non-surgical therapies, versus any comparator, for small hepatocellular carcinoma. Randomised controlled trials were quality assessed using the Cochrane Risk of Bias 2 tool and mapped. The comparative effectiveness of therapies was assessed using network meta-analysis. A threshold analysis was used to identify which comparisons were sensitive to potential changes in the evidence. Where comparisons based on randomised controlled trial evidence were not robust or no randomised controlled trials were identified, a targeted systematic review of non-randomised, prospective comparative studies provided additional data for repeat network meta-analysis and threshold analysis. The feasibility of undertaking economic modelling was explored. A workshop with patients and clinicians was held to discuss the findings and identify key priorities for future research.

Results

Thirty-seven randomised controlled trials (with over 3700 relevant patients) were included in the review. The majority were conducted in China or Japan and most had a high risk of bias or some risk of bias concerns. The results of the network meta-analysis were uncertain for most comparisons. There was evidence that percutaneous ethanol injection is inferior to radiofrequency ablation for overall survival (hazard ratio 1.45, 95% credible interval 1.16 to 1.82), progression-free survival (hazard ratio 1.36, 95% credible interval 1.11 to 1.67), overall recurrence (relative risk 1.19, 95% credible interval 1.02 to 1.39) and local recurrence (relative risk 1.80, 95% credible interval 1.19 to 2.71). Percutaneous acid injection was also inferior to radiofrequency ablation for progression-free survival (hazard ratio 1.63, 95% credible interval 1.05 to 2.51). Threshold analysis showed that further evidence could plausibly change the result for some comparisons. Fourteen eligible non-randomised studies were identified (n ≥ 2316); twelve had a high risk of bias so were not included in updated network meta-analyses. Additional non-randomised data, made available by a clinical advisor, were also included (n = 303). There remained a high level of uncertainty in treatment rankings after the network meta-analyses were updated. However, the updated analyses suggested that microwave ablation and resection are superior to percutaneous ethanol injection and percutaneous acid injection for some outcomes. Further research on stereotactic ablative radiotherapy was recommended at the workshop, although it is only appropriate for certain patient subgroups, limiting opportunities for adequately powered trials.

Limitations

Many studies were small and of poor quality. No comparative studies were found for some therapies.

Conclusions

The existing evidence base has limitations; the uptake of specific ablative therapies in the United Kingdom appears to be based more on technological advancements and ease of use than strong evidence of clinical effectiveness. However, there is evidence that percutaneous ethanol injection and percutaneous acid injection are inferior to radiofrequency ablation, microwave ablation and resection.

Study registration

PROSPERO CRD42020221357.

Funding

This award was funded by the National Institute for Health and Care Research (NIHR) Health Technology Assessment (HTA) programme (NIHR award ref: NIHR131224) and is published in full in Health Technology Assessment; Vol. 27, No. 29. See the NIHR Funding and Awards website for further award information.

Stereotactic Microwave Ablation of Hepatocellular Carcinoma: The Impact of Tumor Size and Minimal Ablative Margin on Therapeutic Success

BACKGROUND

Microwave ablation (MWA) has gained relevance in the treatment of hepatic malignancies and especially in hepatocellular carcinoma (HCC), and it is an important alternative to surgery. The purpose of the study was to evaluate whether the minimal ablative margin (MAM) or the initial tumor size has a greater effect on the success of stereotactic MWA of HCC regarding the time to local tumor progression (LTP) and overall survival (OS).

METHODS

88 patients, who received stereotactic MWA of 127 tumor lesions with a curative intention were included in this single-center, retrospective study. The MAM was evaluated in a side-by-side comparison of pre- and post-ablative, contrast-enhanced slice imaging. A Cox proportional hazard model with a frailty term was computed to assess the influence of the MAM and the maximum tumor diameter on the time to LTP and the OS.

RESULTS

The maximum tumor diameter was identified as a significant positive predictor for LTP (hazard ratio 1.04, 95% CI 1.00-1.08, p = 0.03), but it was not a significant positive predictor for the OS (p = 0.20). The MAM did not have a significant influence on LTP-free survival (p = 0.23) and OS (p = 0.67).

CONCLUSION

For the successful stereotactic MWA of HCC, the MAM and maximum tumor diameter might not have an influence on the OS, but the maximum tumor diameter seems to be an independent predictor of the time to LTP.

Evaluation of a New CT-Guided Robotic System for Percutaneous Needle Insertion for Thermal Ablation of Liver Tumors: A Prospective Pilot Study

PURPOSE

To assess the feasibility and safety of a robotic system for percutaneous needle insertion during thermal ablation of liver tumors.

MATERIALS AND METHODS

This study analyzed the CT-guided percutaneous needle insertion using the EPIONE robotic device (Quantum Surgical, Montpellier, France) for radiofrequency or microwave liver ablation. The main criteria of the study were feasibility (possibility to perform the thermal ablation after needle insertion), the number of needle adjustments (reiteration of robotically assisted needle insertion when initial needle positioning is considered insufficient to perform ablation), and robotic-guided procedure safety (complications related to the needle insertion). Patients were followed up at 6 months post-intervention to assess local tumor control.

RESULTS

Twenty-one patients with 24 tumors, including 6 HCC and 18 metastases measuring 15.6 ± 7.2 mm, were enrolled. One patient (with one tumor) was excluded for protocol deviation. Robotic assisted thermal ablation was feasible for 22/23 lesions (95.7%) and 19/20 patients (95.0%), as validated by a data safety monitoring Board (95% CI [76.39%; 99.11%]) for the per-protocol population. The mean number of needle adjustments per tumor treated was 0.4 (SD: 0.7), with 70.8% of tumors requiring no adjustment. No adverse events were depicted. Rate of local tumor control was 83.3% for patients and 85.7% for tumors, at 6 months.

CONCLUSION

This bicentric first-in-human pilot study suggests both feasibility and safety of a stereotactic CT-guided EPIONE device for the percutaneous needle insertion during liver tumor thermal ablation.

Update on Percutaneous Local Ablative Procedures for the Treatment of Hepatocellular Carcinoma

BACKGROUND

 Hepatocellular carcinoma (HCC) is the fifth most common tumor worldwide. Because many hepatocellular carcinomas are already unresectable at the time of initial diagnosis, percutaneous tumor ablation has become established in recent decades as a curative therapeutic approach for very early (BCLC 0) and early (BCLC A) HCC. The aim of this paper is to provide a concise overview of the percutaneous local ablative procedures currently in use, based on their technical characteristics as well as clinical relevance, taking into account the current body of studies.

MATERIALS AND METHODS

 The literature search included all original papers, reviews, and meta-analyses available via MEDLINE and Pubmed on the respective percutaneous ablation procedures; the primary focus was on randomized controlled trials and publications from the last 10 years.

RESULTS AND CONCLUSIONS

 Radiofrequency ablation (RFA) and microwave ablation (MWA) are well-established procedures that are considered equal to surgical resection in the treatment of stage BCLC 0 and A HCC with a diameter up to 3 cm due to their strong evidence in international and national guidelines. For tumors with a diameter between 3 and 5 cm, the current S3 guidelines recommend a combination of transarterial chemoembolization (TACE) and thermal ablation using RFA or MWA as combination therapy is superior to thermal ablation alone in tumors of this size and shows comparable results to surgical resection in terms of overall survival. Alternative, less frequently employed thermal procedures include cryotherapy (CT) and laser ablation (LA). Non-thermal procedures include irreversible electroporation (IRE), interstitial brachytherapy (IBT), and most recently, electrochemotherapy (ECT). Due to insufficient evidence, these have only been used in individual cases and within the framework of studies. However, the nonthermal methods are a reasonable alternative for ablation of tumors adjacent to large blood vessels and bile ducts because they cause significantly less damage to these structures than thermal ablation methods. With advances in the technology of the respective procedures, increasingly good evidence, and advancements in supportive techniques such as navigation devices and fusion imaging, percutaneous ablation procedures may expand their indications for the treatment of larger and more advanced tumors in the coming years.

KEY POINTS

· RFA and MWA are considered equal to surgical resection as a first-line therapy for the curative treatment of stage BCLC 0 and A HCCs with a diameter of up to 3 cm.. · For HCCs with a diameter between 3 and 5 cm, a combination of TACE and RFA or MWA is recommended. This combination therapy yields results comparable to those of surgical resection in terms of overall survival.. · Due to insufficient evidence, alternative ablation methods have only been used in individual cases and within the framework of studies. However, nonthermal methods, such as IRE, IBT, and, most recently, ECT, are a reasonable alternative for ablation of HCCs adjacent to large blood vessels and bile ducts because they cause significantly less damage to these structures than thermal ablation methods..

CITATION FORMAT

· Luerken L, Haimerl M, Doppler M et al. Update on Percutaneous Local Ablative Procedures for the Treatment of Hepatocellular Carcinoma. Fortschr Röntgenstr 2022; DOI: 10.1055/a-1768-0954.

Stereotactic navigation versus ultrasound guidance in placing IRE applicators in a liver phantom

The aim of this study was to compare the accuracy of stereotactic CT-guided navigation and ultrasound guided navigation for placing electrodes in Irreversible electroporation in a liver phantom. A liver phantom with multiple tumours was used and interventionists placed four IRE electrodes around each tumour guided either by stereotactic CT-guided navigation or ultrasound. The goal was to place them in a perfect 20 × 20 mm square with parallel electrodes. After each treatment, a CT-scan was performed. The accuracy in pairwise electrode distance, pairwise parallelism and time per tumour was analysed. Eight interventionists placed four electrodes around 55 tumours, 25 with ultrasound and 30 with stereotactic CT-guided navigation. 330 electrode pairs were analysed, 150 with ultrasound and 180 with stereotactic CT-navigation. The absolute median deviation from the optimal distance was 1.3 mm (range 0.0 to 11.3 mm) in the stereotactic CT-navigation group versus 7.1 mm (range 0.3 to 18.1 mm) in the Ultrasound group (p < 0.001). The mean angle between electrodes in each pair was 2.7 degrees (95% CI 2.4 to 3.1 degrees) in the stereotactic CT-navigation group and 5.5 degrees (95% CI 5.0 to 6.1 degrees) in the Ultrasound group (p < 0.001). The mean time for placing the electrodes was 15:11 min (95% CI 13:05 to 17:18 min) in the stereotactic CT-navigation group and 6:40 min (95% CI 5:28 to 7:52 min) in the Ultrasound group. The use of stereotactic CT-navigation in placing IRE-electrodes in a liver phantom is more accurate, but more time consuming, compared to ultrasound guidance.

Stereotactic and Robotic Minimally Invasive Thermal Ablation of Malignant Liver Tumors: A Systematic Review and Meta-Analysis

Background

Stereotactic navigation techniques aim to enhance treatment precision and safety in minimally invasive thermal ablation of liver tumors. We qualitatively reviewed and quantitatively summarized the available literature on procedural and clinical outcomes after stereotactic navigated ablation of malignant liver tumors.

Methods

A systematic literature search was performed on procedural and clinical outcomes when using stereotactic or robotic navigation for laparoscopic or percutaneous thermal ablation. The online databases Medline, Embase, and Cochrane Library were searched. Endpoints included targeting accuracy, procedural efficiency, and treatment efficacy outcomes. Meta-analysis including subgroup analyses was performed.

Results

Thirty-four studies (two randomized controlled trials, three prospective cohort studies, 29 case series) were qualitatively analyzed, and 22 studies were included for meta-analysis. Weighted average lateral targeting error was 3.7 mm (CI 3.2, 4.2), with all four comparative studies showing enhanced targeting accuracy compared to free-hand targeting. Weighted average overall complications, major complications, and mortality were 11.4% (6.7, 16.1), 3.4% (2.1, 5.1), and 0.8% (0.5, 1.3). Pooled estimates of primary technique efficacy were 94% (89, 97) if assessed at 1–6 weeks and 90% (87, 93) if assessed at 6–12 weeks post ablation, with remaining between-study heterogeneity. Primary technique efficacy was significantly enhanced in stereotactic vs. free-hand targeting, with odds ratio (OR) of 1.9 (1.2, 3.2) (n = 6 studies).

Conclusions

Advances in stereotactic navigation technologies allow highly precise and safe tumor targeting, leading to enhanced primary treatment efficacy. The use of varying definitions and terminology of safety and efficacy limits comparability among studies, highlighting the crucial need for further standardization of follow-up definitions.

Image-Guided Ablation for Colorectal Liver Metastasis: Principles, Current Evidence, and the Path Forward

Simple Summary

Colorectal cancer is the fourth most common type of cancer globally. Approximately 20% of patients with colorectal cancer present with synchronous liver metastases, and up to 60% will develop metachronous metastases during the course of the disease. Although liver resection is currently considered the local treatment of choice for colorectal liver metastasis (CLM), less than one-third of patients are eligible for surgery at the time of diagnosis of CLM. Ablation is a well-established, less invasive, locoregional therapy for patients with small CLMs, which has shown favorable oncological outcomes in patients with unresectable CLMs, comparable to those in patients eligible for surgery. The increasing knowledge of factors affecting oncological outcomes has allowed selected patients with resectable small volume CLMs to be treated with thermal ablation with curative intent. The continuous technological evolutions in imaging and image guidance have contributed to this paradigm shift in CLM treatment. The importance of patient selection, patient factors, tumor factors, ablation techniques, and clinical applications is discussed in this article.

Abstract

Image-guided ablation can provide effective local tumor control in selected patients with CLM. A randomized controlled trial suggested that radiofrequency ablation combined with systemic chemotherapy resulted in a survival benefit for patients with unresectable CLM, compared to systemic chemotherapy alone. For small tumors, ablation with adequate margins can be considered as an alternative to resection. The improvement of ablation technologies can allow the treatment of tumors close to major vascular structures or bile ducts, on which the applicability of thermal ablation modalities is challenging. Several factors affect the outcomes of ablation, including but not limited to tumor size, number, location, minimal ablation margin, RAS mutation status, prior hepatectomy, and extrahepatic disease. Further understanding of the impact of tumor biology and advanced imaging guidance on overall patient outcomes might help to tailor its application, and improve outcomes of image-guided ablation.

Stereotactic Percutaneous Electrochemotherapy as Primary Approach for Unresectable Large HCC at the Hepatic Hilum

Electrochemotherapy (ECT) is a novel non-thermal ablative technique that combines chemotherapy and the application of electric pulses for reversible cell membrane electroporation. This method was recently performed in the treatment of deep-seated liver tumors during open surgery but experience about percutaneous ECT is rare and further developments like combination of percutaneous ECT with stereotactic navigated devices may be very promising. We report on a case of a 4.7 × 4.5 × 3.5 cm unresectable HCC at the hepatic hilum adjacent to the major vessels and the bile duct that was successfully treated using percutaneous ECT in combination with stereotactic navigation. Follow-up imaging 6 weeks and 6 months after ECT showed complete response.

Accuracy of Electrode Placement in IRE Treatment with Navigated Guidance

Purpose

Evaluate the accuracy of multiple electrode placements in IRE treatment of liver tumours using a stereotactic CT-based navigation system.

Method

Analysing data from all IRE treatments of liver tumours at one institution until 31 December 2018. Comparing planned with validated electrode placement. Analysing lateral and angular errors and parallelism between electrode pairs

Results

Eighty-four tumours were treated in 60 patients. Forty-six per cent were hepatocellular carcinoma, and 36% were colorectal liver metastases. The tumours were located in all segments of the liver. Data were complete from 51 treatments. Two hundred and six electrodes and 336 electrode pairs were analysed. The median lateral and angular error, comparing planned and validated electrode placement, was 3.6 mm (range 0.2–13.6 mm) and 3.1° (range 0°–16.1°). All electrodes with a lateral error >10 mm were either re-positioned or excluded before treatment. The median angle between the electrode pairs was 3.8° (range 0.3°–17.2°). There were no electrode placement-related complications.

Conclusion

The use of a stereotactic CT-based system for navigation of electrode placement in IRE treatment of liver tumours is safe, accurate and user friendly.

Primary efficacy of percutaneous microwave ablation of malignant liver tumors: comparison of stereotactic and conventional manual guidance

In this study, we compare the primary efficacy of computed tomography-navigated stereotactic guidance to that of manual guidance for percutaneous microwave ablation of liver malignancies. In total, 221 patients (140, 17, and 64 with hepatocellular carcinoma, cholangiocellular carcinoma, and liver metastases, respectively) with 423 treated liver lesions underwent microwave ablation (MWA). Manual guidance (M) and stereotactic guidance (S) were used for 136 and 287 lesions, respectively. The primary endpoint was the primary efficacy and the secondary endpoint was the radiation dose. A generalised estimating equation was applied to analyse the correlation between the primary efficacy (lesion basis) and the type of guidance, size and location of lesion. The primary efficacy rate was significantly higher in the S-group (84.3%) than in the M-group (75.0%, p = 0.03). Lesion size > 30 mm was negatively correlated with the efficacy rate (odds ratio 0.38; 95% confidence interval 0.20–0.74). Stereotactic guidance was associated with a significantly lower dose length product (p < 0.01). In this retrospective study, percutaneous microwave ablation under stereotactic guidance exhibited significantly greater primary efficacy than conventional manual guidance.

Value of MRI/CT Image Fusion for Targeting "invisible" Lesions in Stereotactic Microwave Ablation (SMWA) of Malignant Liver Lesions: A Retrospective Analysis

PURPOSE

To assess the technical feasibility of MRI/CT image fusion and completeness of ablation treatment for primary or metastatic liver lesions invisible on contrast-enhanced CT planning scans and outcome in patients treated with stereotactic microwave ablation (SMWA).

MATERIALS AND METHODS

The study was approved by the local ethics committee. Patients who underwent SMWA between January 2015 and December 2018 were retrospectively analyzed. All liver lesions for which MRI/CT fusion was performed due to invisibility on pre-interventional CT planning scans were included and reassessed. The outcome measurement was successful ablation of the lesion at first follow-up imaging.

RESULTS

During the study period, 236 patients underwent 312 SMWAs with ablation of 496 lesions. Twenty-four lesions in 15 patients (mean age, 62 years; range, 43-80 years) were included. Following MRI/CT image fusion, all 24 lesions could be sufficiently localized to perform SMWA. The first follow-up imaging showed complete ablation of 22 lesions. Two initially incompletely ablated lesions were hepatocellular carcinomas and were successfully re-ablated afterwards.

CONCLUSION

SMWA with MRI/CT image fusion is an accurate and safe treatment option for patients with liver lesions not detectable on contrast-enhanced CT planning scans. MRI/CT image fusion may allow more patients with malignant liver lesions to benefit from local ablation treatment even if their lesions are not visible on CT planning examinations.

Stereotactic Image-Guided Microwave Ablation for Malignant Liver Tumors-A Multivariable Accuracy and Efficacy Analysis

Background: Therapeutic success of thermal ablation for liver tumors depends on precise placement of ablation probes and complete tumor destruction with a safety margin. We investigated factors influencing targeting accuracy and treatment efficacy of percutaneous stereotactic image-guided microwave ablation (SMWA) for malignant liver neoplasms. Materials and methods: All consecutive patients treated with SMWA for malignant liver tumors over a 3-year period were analyzed. A computed tomography-based navigation system was used for ablation probe trajectory planning, stereotactic probe positioning, and validation of probe positions and ablation zones. Factors potentially influencing targeting accuracy [target positioning error (TPE)] and treatment efficacy within 6 months [ablation site recurrence (ASR)] were analyzed in a multivariable regression model, including challenging lesion locations (liver segments I, VII, and VIII; subphrenic location). Results: Three hundred one lesions (174 hepatocellular carcinomas, 87 colorectal liver metastases, 17 neuroendocrine tumors, and 23 others) were targeted in 191 interventions in 153 patients. The median TPE per ablation probe was 2.9 ± 2.3 mm (n = 384). Correction of ablation probe positions by repositioning was necessary in 4 out of 301 lesions (1%). Factors significantly influencing targeting accuracy were cirrhosis (R 0.67, CI 0.22-1.12) and targeting trajectory length (R 0.21, CI 0.12-0.29). Factors significantly influencing early ASR were lesion size >30 mm (OR 5.22, CI 2.44-11.19) and TPE >5 mm (OR 2.48, CI 1.06-5.78). Challenging lesion locations had no significant influence on targeting accuracy or early ASR. Conclusions: SMWA allows precise and effective treatment of malignant liver tumors even for lesions in challenging locations, with treatment efficacy depending on targeting accuracy in our model. Allowing for many tumors to be safely reached, SMWA has the potential to broaden treatment eligibility for patients with otherwise difficult to target tumors.

Improvement of the primary efficacy of microwave ablation of malignant liver tumors by using a robotic navigation system

Background The aim of the study was to assess the primary efficacy of robot-assisted microwave ablation and compare it to manually guided microwave ablation for percutaneous ablation of liver malignancies. Patients and methods We performed a retrospective single center evaluation of microwave ablations of 368 liver tumors in 192 patients (36 female, 156 male, mean age 63 years). One hundred and nineteen ablations were performed between 08/2011 and 03/2014 with manual guidance, whereas 249 ablations were performed between 04/2014 and 11/2018 using robotic guidance. A 6-week follow-up (ultrasound, computed tomography and magnetic resonance imaging) was performed on all patients. Results The primary technique efficacy outcome of the group treated by robotic guidance was significantly higher than that of the manually guided group (88% vs. 76%; p = 0.013). Multiple logistic regression analysis indicated that a small tumor size (≤ 3 cm) and robotic guidance were significant favorable prognostic factors for complete ablation. Conclusions In addition to a small tumor size, robotic navigation was a major positive prognostic factor for primary technique efficacy.

CAN MICROWAVE ABLATION BE AN ALTERNATIVE TO RESECTION FOR THE TREATMENT OF NEUROENDOCRINE LIVER METASTASES?

Objective: Surgical resection of neuroendocrine tumor liver metastases has been proven to improve survival, but the benefit of microwave ablation as an alternative or adjunct to surgery has yet to be assessed. Our hypothesis is that ablation is equal to surgery in terms of local recurrence and survival. Methods: We conducted a retrospective analysis including all patients treated with microwave ablation and/or surgical resection for neuroendocrine liver metastases in our institution between 2008 and 2017. Results: A total of 47 patients and 68 treatments were analyzed, including 34 liver resections, 20 ablations, and 14 combined procedures. A total of 130 individual metastases were treated with ablation, representing a median of 4 per session (range 1-30). While no major complications occurred after ablation, we observed 11 minor and 3 major complications after open surgical resection (P = .0135). Length of stay was significantly shorter after ablation (P = .0008). The majority of patients (33/47, 70.2%) underwent curative procedures, 14 patients underwent (29.8%) debulking procedures. There was no difference in local recurrence rate between tumors treated with ablation or resection. Liver-only disease progression was detected in 29% of the patients and overall progression was detected in 66% of the patients. The mean survival was not significantly different between patients treated with ablation only versus resection with or without ablation (P = .1570). Overall survival was mean 75.3 months (6 to 374 months). Conclusion: Depending on the extent of the liver metastases, microwave ablation might be a safe alternative or addition to resection for neuroendocrine tumor liver metastases with low morbidity and high local efficiency. Abbreviations: CT = computed tomography; MWA = microwave ablation; NET = neuroendocrine tumor; PET = positron emission tomography; RFA = radiofrequency ablation; RFS = recurrence-free survival; SMWA = stereotactic microwave ablation.

Stereotactic image-guided microwave ablation of hepatocellular carcinoma using a computer-assisted navigation system

BACKGROUND & AIMS

Ablation plays an important role in the treatment of hepatocellular carcinoma. Because image-guided navigation technology has recently entered the clinical setting, we aimed to analyse its safety, therapeutic and procedural efficiency.

METHODS

Retrospective analysis of patients treated with stereotactic image-guided microwave ablation (SMWA) between January 2015 and December 2017. Interventions were performed using computertomography-guidance with needle trajectory, ablation planning and automatic single-marker patient registration. Needle placement and ablation coverage was controlled by image fusion under general anaesthesia with jet-ventilation.

RESULTS

In total 174 ablations were performed in 88 patients during 119 interventions. Mean age was 66 (46-84) years, 74 (84.1%) were men and 74% were Child Pugh Class A. Median tumour size was 16 (4-45) mm, 62.2% were BCLC A. Median lateral and longitudinal error of needle placement were 3.2 (0.2-14.1) and 1.6 (0-15.8) mm. Median one tumour (1-4) was ablated per session. One patient developed a Dindo IIIb (0.8%) complication, six minor complications. After re-ablation of 12 lesions, an efficacy rate of 96.3% was achieved. Local tumour progression was 6.3% (11/174). Close proximity to major vessels was significantly correlated with local tumour progression (P < .05). Median overall follow-up was 17.5 months after intervention and 24 months after initial diagnosis. BCLC stage, child class and previous treatment were significantly correlated with overall survival (P < .05).

CONCLUSION

Stereotactic image-guided microwave ablation is a safe and efficient treatment for HCC offering a curative treatment approach in general and in particular for lesions not detectable on conventional imaging or untreatable because of difficult anatomic locations.

Percutaneous stereotactic image-guided microwave ablation for malignant liver lesions

Thermal ablation has proven beneficial for hepatocellular carcinoma and possibly for colorectal liver metastases, but data is lacking for other liver metastases. Computer-assisted navigation can increase ablation efficacy and broaden its indications. We present our experience with percutaneous stereotactic image-guided microwave ablation (SMWA) for non-colorectal liver metastases (NCRLM), in form of a retrospective study including all SMWA for NCRLM from 2015 to 2017. Indication for SMWA was determined at a multidisciplinary tumorboard. End-points include recurrence, overall and liver-specific disease progression and complications. Twenty-three patients underwent 25 interventions for 40 lesions, including 17 neuroendocrine tumor, nine breast cancer, four sarcoma, two non-small cell lung cancer, three duodenal adenocarcinoma, one esophageal adenocarcinoma, one pancreatic adenocarcinoma, one ampullary carcinoma, one prostate carcinoma, and one renal cell carcinoma metastases. Median follow-up was 15 months (2-32). Incomplete ablation rate was 2.5% (1/40), local recurrence rate 10% (4/40). Three patients (12%) had minor complications. Overall disease progression was 73.9% (17/23), median disease-free survival 7 months (0-26) and overall survival 18 months (2-39). SIMWA is feasible, safe and minimally invasive for NCRLM in selected patients. While it might offer an alternative to resection or palliative strategies, the oncological benefit needs to be evaluated in a larger patient cohort.