Thermal ablation with configurable shapes: a comprehensive, automated model for bespoke tumor treatment

BACKGROUND

Malignant tumors routinely present with irregular shapes and complex configurations. The lack of customization to individual tumor shapes and standardization of procedures limits the success and application of thermal ablation.

METHODS

We introduced an automated treatment model consisting of (i) trajectory and ablation profile planning, (ii) ablation probe insertion, (iii) dynamic energy delivery (including robotically driven control of the energy source power and location over time, according to a treatment plan bespoke to the tumor shape), and (iv) quantitative ablation margin verification. We used a microwave ablation system and a liver phantom (acrylamide polymer with a thermochromic ink) to mimic coagulation and measure the ablation volume. We estimated the ablation width as a function of power and velocity following a probabilistic model. Four representative shapes of liver tumors < 5 cm were selected from two publicly available databases. The ablated specimens were cut along the ablation probe axis and photographed. The shape of the ablated volume was extracted using a color-based segmentation method.

RESULTS

The uncertainty (standard deviation) of the ablation width increased with increasing power by ± 0.03 mm (95% credible interval [0.02, 0.043]) per watt increase in power and by ± 0.85 mm (95% credible interval [0, 2.5]) per mm/s increase in velocity. Continuous ablation along a straight-line trajectory resulted in elongated rotationally symmetric ablation shapes. Simultaneous regulation of the power and/or translation velocity allowed to modulate the ablation width at specific locations.

CONCLUSIONS

This study offers the proof-of-principle of the dynamic energy delivery system using ablation shapes from clinical cases of malignant liver tumors.

RELEVANCE STATEMENT

The proposed automated treatment model could favor the customization and standardization of thermal ablation for complex tumor shapes.

KEY POINTS

• Current thermal ablation systems are limited to ellipsoidal or spherical shapes. • Dynamic energy delivery produces elongated rotationally symmetric ablation shapes with varying widths. • For complex tumor shapes, multiple customized ablation shapes could be combined.

Management of patients at the hepatopancreatobiliary unit of a London teaching hospital during the COVID-19 pandemic

To mitigate COVID-19-related shortage of treatment capacity, the hepatopancreatobiliary (HPB) unit of the Royal Free Hospital London (RFHL) transferred its practice to independent hospitals in Central London through the North Central London Cancer Alliance. The aim of this study was to critically assess this strategy and evaluate perioperative outcomes. Prospectively collected data were reviewed on all patients who were treated under the RFHL HPB unit in six hospitals between November 2020 and October 2021. A total of 1541 patients were included, as follows: 1246 (81%) at the RFHL, 41 (3%) at the Chase Farm Hospital, 23 (2%) at the Whittington Hospital, 207 (13%) at the Princess Grace Hospital, 12 (1%) at the Wellington Hospital and 12 (1%) at the Lister Hospital, Chelsea. Across all institutions, overall complication rate were 40%, major complication (Clavien-Dindo grade ≥ 3a) rate were 11% and mortality rates were 1.4%, respectively. In COVID-19-positive patients (n = 28), compared with negative patients, complication rate and mortality rates were increased tenfold. Outsourcing HPB patients, including their specialist care, to surrounding institutions was safe and ensured ongoing treatment with comparable outcomes among the institutions during the COVID-19 pandemic. Due to the lack of direct comparison with a non-pandemic cohort, these results can strictly only be applied within a pandemic setting.

A prospective multicentre trial on survival after Microwave Ablation VErsus Resection for Resectable Colorectal liver metastases (MAVERRIC)

AIM

This multi-centre prospective cohort study aimed to investigate non-inferiority in patients' overall survival when treating potentially resectable colorectal cancer liver metastasis (CRLM) with stereotactic microwave ablation (SMWA) as opposed to hepatic resection (HR).

METHODS

Patients with no more than 5 CRLM no larger than 30 mm, deemed eligible for both SMWA and hepatic resection at the local multidisciplinary team meetings, were deliberately treated with SMWA (study group). The contemporary control group consisted of patients with no more than 5 CRLM, none larger than 30 mm, treated with HR, extracted from a prospectively maintained nationwide Swedish database. After propensity-score matching, 3-year overall survival (OS) was compared as the primary outcome using Kaplan-Meier and Cox regression analyses.

RESULTS

All patients in the study group (n = 98) were matched to 158 patients from the control group (mean standardised difference in baseline covariates = 0.077). OS rates at 3 years were 78% (Confidence interval [CI] 68-85%) after SMWA versus 76% (CI 69-82%) after HR (stratified Log-rank test p = 0.861). Estimated 5-year OS rates were 56% (CI 45-66%) versus 58% (CI 50-66%). The adjusted hazard ratio for treatment type was 1.020 (CI 0.689-1.510). Overall and major complications were lower after SMWA (percentage decrease 67% and 80%, p < 0.01). Hepatic retreatments were more frequent after SMWA (percentage increase 78%, p < 0.01).

CONCLUSION

SMWA is a valid curative-intent treatment alternative to surgical resection for small resectable CRLM. It represents an attractive option in terms of treatment-related morbidity with potentially wider options regarding hepatic retreatments over the future course of disease.

Ablation versus resection for resectable colorectal liver metastases - Health care related cost and survival analyses from a quasi-randomised study

BACKGROUND

The aim of this study was to compare healthcare related costs and survival in patients treated with microwave ablation (MWA) versus surgical resection for resectable colorectal liver metastases (CRLM), in patients from a quasi-randomised setting.

METHODS

The Swedish subset of data from a prospective multi-centre study investigating survival after percutaneous computer-assisted Microwave Ablation VErsus Resection for Resectable CRLM (MAVERRIC study) was analysed. Patients with CRLM ≤ 3 cm amenable to ablation and resection were considered for study inclusion only on even calendar weeks, while treated with gold standard resection every other week, creating a quasi-randomised setting. Survival and costs (all inpatient hospital admissions, outpatient visits, oncological treatments and radiological imaging) in the 2 years following treatment were investigated.

RESULTS

MWA (n = 52) and resection (n = 53) cohorts had similar baseline patient and tumour characteristics and health care consumption within 1 year prior to CRLM treatment. Treatment related morbidity and length of stay were significantly higher in the resected cohort. Overall health care related costs from decision of treatment and 2 years thereafter were lower in the MWA versus resection cohort (mean ± SD USD 80'964±59'182 versus 110'059±59'671, P < 0.01). Five-year overall survival was 50% versus 54% in MWA versus resection groups (P = 0.95).

CONCLUSIONS

MWA is associated with decreased morbidity, time spent in medical facilities and healthcare related costs within 2 years of initial treatment with equal overall survival, highlighting its benefits for patient and health care systems.

Enhanced recovery for liver transplantation: recommendations from the 2022 International Liver Transplantation Society consensus conference

There is much controversy regarding enhanced recovery for recipients of liver transplants from deceased and living donors. The objectives of this Review were to summarise current knowledge on individual enhanced recovery elements on short-term outcomes, identify key components for comprehensive pathways, and create internationally accepted guidelines on enhanced recovery for liver-transplant recipients. The ERAS4OLT.org collaborative partnered by the International Liver Transplantation Society performed systematic literature reviews on the effect of 32 relevant enhanced perioperative recovery elements on short-term outcomes, and global specialists prepared expert statements on deceased and living donor liver transplantation. The Grading Recommendations, Assessment, Development and Evaluations approach was used for rating of quality of evidence and grading of recommendations. A virtual international consensus conference was held in January, 2022, in which results were presented, voted on by the audience, and discussed by an independent international jury of eight members, applying the Danish model of consensus. 273 liver transplantation specialists from 30 countries prepared expert statements on elements of enhanced recovery for liver transplantation based on the systematic literature reviews. The consensus conference yielded 80 final recommendations, covering aspects of enhanced recovery for preoperative assessment and optimisation, intraoperative surgical and anaesthetic conduct, and postoperative management for the recipients of liver transplants from both deceased and living donors, and for the living donor. The recommendations represent a comprehensive overview of the relevant elements and areas of enhanced recovery for liver transplantation. These internationally established guidelines could direct the development of enhanced recovery programmes worldwide, allowing adjustments according to local resources and practices.

The role of early extubation on short-term outcomes after liver transplantation - A systematic review, meta-analysis and expert recommendations

BACKGROUND

Early extubation in liver transplantation (LT) and its potential benefits such as reduction in pulmonary complications and enhanced postoperative recovery have been described. The extent of the effect of early extubation on short-term outcomes after LT across the published literature is to the best of our knowledge unknown.

OBJECTIVES

The objective of this systematic review and meta-analysis was to determine whether early extubation improves immediate and short-term outcomes after LT and to provide expert recommendations.

DATA SOURCES

Ovid MEDLINE, Embase, Scopus, Google Scholar, and Cochrane Central.

METHODS

A systematic review and meta-analysis on short-term outcomes after early extubation in LT was performed (CRD42021241402), following PRISMA guidelines and quality of evidence (QOE) and recommendations grading using the GRADE approach, derived from an international experts panel. Endpoints were reintubation rates, pulmonary and other complications/organ dysfunction, intensive care unit (ICU) and hospital length of stay (LOS).

RESULTS

Of 831 screened articles, 20 observational studies with a total of 3573 patients addressing early extubation protocols were included, of which 12 studies compared results after early versus deferred extubation. Reintubation and pulmonary complication rates were lower in the early versus deferred extubation groups (OR 0.29, CI 0.22-0.39; OR 0.17, CI 0.09-0.33, respectively). ICU and hospital LOS were shorter in eight out of eight and seven out of eight comparative studies, respectively.

CONCLUSIONS

Early extubation after LT is associated with improved short-term outcomes after LT and should be performed in the majority of patients (QOE; Moderate to low | Grade of Recommendation; Strong). Randomized controlled trials using standardized definitions of early extubation and short-term outcomes are needed to demonstrate causality, validate and allow comparability of the results.

New ERAS in liver transplantation - Past, present, and next steps

There are parallels between the history of Enhanced Recovery after Surgery (ERAS) and liver transplantation. Both have been established and advanced by innovative individuals, often going against perceived wisdom and convention. Liver transplantation has traditionally been considered too complex for ERAS pathways, despite a small number of trials showing them to be both safe and of benefit. To date, there are very few randomized controlled trials and cohort studies publishing outcomes on liver transplant patients enrolled in comprehensive ERAS pathways. To progress our field, the 2022 International Liver Transplantation Society's Consensus Conference has created expert panels to analyze the evidence in 32 domains of the liver transplantation pathway using the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) approach to generate expert recommendations. These recommendations will be voted on by the international community to gain consensus using the Danish model, and create the ERAS4OLT.org Enhanced Recovery after Liver Transplantation Pathway.

Are short-term complications associated with poor allograft and patient survival after liver transplantation? A systematic review of the literature and expert panel recommendations

BACKGROUND

Maximizing patient and allograft survival after liver transplant (LT) is important from both a patient care and organ utilization perspective. Although individual studies have addressed the effects of short-term post-LT complications on a limited scale, there has not been a systematic review of the literature formally assessing the potential effects of early complications on long-term outcomes.

OBJECTIVES

To identify whether short-term complications after LT affect allograft and overall survival, to identify short-term complications of particular clinical interest and significance, and to provide recommendations to improve post-LT graft and patient survival.

DATA SOURCES

Ovid MEDLINE, Embase, Scopus, Google Scholar, and Cochrane Central.

METHODS

A systematic review following PRISMA guidelines and recommendations using the GRADE approach derived from an international expert panel.

RESULTS

The literature review and analysis provided show that short-term complications have a large impact on allograft and patient survival after LT. The complications with the strongest effect on survival are acute kidney injury (AKI), biliary complications, and early allograft dysfunction (EAD).

CONCLUSION

This panel recommends taking measures to reduce the risk and incidence of short-term complications post-LT. Clinicians should pay particular attention to preventing or ameliorating AKI, biliary complications, and EAD (Quality of evidence; Moderate | Grade of Recommendation; Strong).

A Platform (Authorships.org) for the Objective Qualification and Order of Academic Authorship in Medical and Science Journals: Development and Evaluation Study Using the Design Science Research Methodology

Background

The qualification and order of authorship in scientific manuscripts are the main disputes in collaborative research work.

Objective

The aim of this project was to develop an open-access web-based platform for objective decision-making of authorship qualification and order in medical and science journals.

Methods

The design science process methodology was used to develop suitable software for authorship qualification and order. The first part of the software was designed to differentiate between qualification for authorship versus acknowledgment, using items of the recommendations of the International Committee of Medical Journal Editors. The second part addressed the order of authorship, using the analytical hierarchy process for objective multiple criteria decision-making and ranking. The platform was evaluated qualitatively (n=30) and quantitatively (n=18) using a dedicated questionnaire, by an international panel of medical and biomedical professionals and research collaborators worldwide.

Results

Authorships.org represents an open-access software compatible with all major platforms and web browsers. Software usability and output were evaluated and presented for 3 existing clinical and biomedical research studies. All 18 international evaluators felt that the Authorships.org platform was easy to use or remained neutral. Moreover, 59% (n=10) were satisfied with the software output results while the rest were unsure, 59% (n=10) would definitely use it for future projects while 41% (n=7) would consider it, 94% (n=16) felt it may prove useful to eliminate disputes regarding authorship, 82% (n=14) felt that it should become mandatory for manuscript submission to journals, and 53% (n=9) raised concerns regarding the potential unethical use of the software as a tool.

Conclusions

Authorships.org allows transparent evaluation of authorship qualification and order in academic medical and science journals. Objectified proof of authorship contributions may become mandatory during manuscript submission in high-quality academic journals.

3D Quantitative Ablation Margins for Prediction of Ablation Site Recurrence After Stereotactic Image-Guided Microwave Ablation of Colorectal Liver Metastases: A Multicenter Study

Background

Three-dimensional (3D) volumetric ablation margin assessment after thermal ablation of liver tumors using software has been described, but its predictive value on treatment efficacy when accounting for other factors known to correlate ablation site recurrence (ASR) remains unknown.

Purpose

To investigate 3D quantitative ablation margins (3D-QAMs) as an algorithm to predict ASR within 1 year after stereotactic microwave ablation (SMWA) for colorectal liver metastases (CRLM).

Materials and Methods

Sixty-five tumors in 47 patients from a prospective multicenter study of patients undergoing SMWA for CRLM were included in this retrospective 3D-QAM analysis. Using a previously developed algorithm, 3D-QAM defined as the distribution of tumor to ablation surface distances was assessed in co-registered pre- and post-ablation CT scans. The discriminatory power and optimal cutoff values for 3D-QAM were assessed using receiver operating characteristic (ROC) curves. Multivariable logistic regression analysis using generalized estimating equations was applied to investigate the impact of various 3D-QAM outputs on 1-year ASR while accounting for other known influencing factors.

Results

Ten of the 65 (15.4%) tumors included for 3D-QAM analysis developed ASR. ROC analyses identified i) 3D-QAM <1 mm for >23% of the tumor surface, ii) 3D-QAM <5 mm for >45%, and iii) the minimal ablation margin (MAM) as the 3D-QAM outputs with optimal discriminatory qualities. The multivariable regression model without 3D-QAM yielded tumor diameter and KRAS mutation as 1-year ASR predictors. When adding 3D-QAM, this factor became the main predictor of 1-year ASR [odds ratio (OR) 21.67 (CI 2.48, 165.21) if defined as >23% <1 mm; OR 0.52 (CI 0.29, 0.95) if defined as MAM].

Conclusions

3D-QAM allows objectifiable and standardized assessment of tumor coverage by the ablation zone after SMWA. Our data shows that 3D-QAM represents the most important factor predicting ASR within 1 year after SMWA of CRLM.

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.

Enhanced recovery after surgery programs improve short-term outcomes after liver transplantation - A systematic review and meta-analysis

This systematic review aimed to investigate the available quality of evidence (QOE) of enhanced recovery after surgery (ERAS) for liver transplantation (LT) on short-term outcomes, grade recommendations and identify relevant components for ERAS protocols. A systematic review and meta-analysis were conducted on short-term outcomes after LT when applying comprehensive ERAS protocols (>1 ERAS component) versus control groups (CRD42021210374), following the GRADE approach for grading quality of evidence and strength of recommendations. Endpoints were morbidity, mortality, length of stay and readmission rates after ERAS for LT. Of 858 screened articles, two randomized controlled trials, 2 prospective and 1 retrospective cohort studies were included (2002 - 2020). Frequent ERAS components were early extubation and postoperative antibiotic, fluid and nutrition management. Overall complications were reduced in ERAS versus control cohorts (OR 0.4 (CI 0.2, 0.7), with no significant differences in mortality and hospital readmission rates. Intensive care unit and hospital length of stay were shorter in ERAS groups (percentage decrease, 55% and 29%, respectively). QOE for individual outcomes was rated moderate to low. ERAS protocols in LT are related to improved short-term outcomes after liver transplantation (Quality of Evidence; Moderate to low | Grade of Recommendation; Strong), but currently lack standardization. This article is protected by copyright. All rights reserved.

Volumetric Quantitative Ablation Margins for Assessment of Ablation Completeness in Thermal Ablation of Liver Tumors

BACKGROUND

In thermal ablation of liver tumors, complete coverage of the tumor volume by the ablation volume with a sufficient ablation margin is the most important factor for treatment success. Evaluation of ablation completeness is commonly performed by visual inspection in 2D and is prone to inter-reader variability. This work aimed to introduce a standardized approach for evaluation of ablation completeness after CT-guided thermal ablation of liver tumors, using volumetric quantitative ablation margins (QAM).

METHODS

A QAM computation metric based on volumetric segmentations of tumor and ablation areas and signed Euclidean surface distance maps was developed, including a novel algorithm to address QAM computation in subcapsular tumors. The code for QAM computation was verified in artificial examples of tumor and ablation spheres simulating varying scenarios of ablation margins. The applicability of the QAM metric was investigated in representative cases extracted from a prospective database of colorectal liver metastases (CRLM) treated with stereotactic microwave ablation (SMWA).

RESULTS

Applicability of the proposed QAM metric was confirmed in artificial and clinical example cases. Numerical and visual options of data presentation displaying substrata of QAM distributions were proposed. For subcapsular tumors, the underestimation of tumor coverage by the ablation volume when applying an unadjusted QAM method was confirmed, supporting the benefits of using the proposed algorithm for QAM computation in these cases. The computational code for developed QAM was made publicly available, encouraging the use of a standard and objective metric in reporting ablation completeness and margins.

CONCLUSION

The proposed volumetric approach for QAM computation including a novel algorithm to address subcapsular liver tumors enables precision and reproducibility in the assessment of ablation margins. The quantitative feedback on ablation completeness opens possibilities for intra-operative decision making and for refined analyses on predictability and consistency of local tumor control after thermal ablation of liver tumors.

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.

Laparoscopic Parenchymal-Sparing Hepatectomy for Multiple Colorectal Liver Metastases Improves Outcomes and Salvageability: A Propensity Score-Matched Analysis

BACKGROUND

Parenchymal-sparing hepatectomy (PSH) is regarded as the standard of care for colorectal liver metastases (CRLMs) in open surgery. However, the surgical and oncological benefits of laparoscopic PSH compared with laparoscopic major hepatectomy (MH) have not been fully documented.

METHODS

A total of 269 patients who underwent initial laparoscopic liver resections with curative intent for CRLMs between 2004 and 2017 were enrolled. Preoperative patient characteristics and tumor burden were adjusted with propensity score matching, and laparoscopic PSH was compared with laparoscopic MH after matching.

RESULTS

PSH was performed in 148 patients, while MH was performed in 121 patients. After propensity score matching, 82 PSH and 82 MH patients showed similar preoperative characteristics. PSH was associated with lower rates of major postoperative complications compared with MH (6.1 vs. 15.9%; p = 0.046). Recurrence-free survival (RFS) and liver-specific RFS rates were comparable between both groups (p = 0.595 and 0.683). Repeat hepatectomy for liver recurrence was more frequently performed in the PSH group (63.9 vs. 36.4%; p = 0.022), and the PSH group also showed a trend toward a higher overall survival (OS) rate (5-year OS 79.4 vs. 64.3%; p = 0.067). Multivariate analyses revealed that initial MH was one of the risk factors to preclude repeat hepatectomy after liver recurrence (hazard ratio 2.39, p = 0.047).

CONCLUSIONS

Laparoscopic PSH provided surgical and oncological benefits for CRLMs, with less complications, similar recurrence rates, and increased salvageability through repeat hepatectomy, compared with laparoscopic MH. PSH should be the standard approach, even in laparoscopic procedures.

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.

Portal hyperperfusion after major liver resection and associated sinusoidal damage is a therapeutic target to protect the remnant liver

Extended liver resection results in loss of a large fraction of the hepatic vascular bed, thereby causing abrupt alterations in perfusion of the remnant liver. Mechanisms of hemodynamic adaptation and associated changes in oxygen metabolism after liver resection and the effect of mechanical portal blood flow reduction were assessed. A pig model (n = 16) of extended partial hepatectomy was established that included continuous observation for 24 h under general anesthesia. Pigs were randomly separated into two groups, one with a portal flow reduction of 70% compared with preoperative values, and the other as a control (n = 8, each). In controls, portal flow [mean (SD)] increased from 74 (8) mL·min^-1·100 g^-1 preoperatively to 240 (48) mL·min^-1·100 g^-1 at 6 h after resection (P < 0.001). Hepatic arterial buffer response was abolished after resection. Oxygen uptake per unit liver mass increased from 4.0 (1.1) mL·min^-1·100 g^-1 preoperatively to 7.7 (1.7) mL·min^-1·100 g^-1 8 h after resection (P = 0.004). Despite this increase in relative oxygen uptake, total hepatic oxygen consumption (V̇o₂) was not maintained, and markers of hypoxia and anaerobic metabolism were significantly increased in hepatocytes after resection. Reduced postoperative portal flow was associated with significantly decreased levels of aspartate aminotransferase and bilirubin and increased hepatic clearance of indocyanine green. In conclusion, major liver resection was associated with persistent portal hyperperfusion, loss of the hepatic arterial buffer response, decreased total hepatic V̇o₂ and with increased anaerobic metabolism. Portal flow modulation by partial portal vein occlusion attenuated liver injury after extended liver resection.NEW & NOTEWORTHY Because of continuous monitoring, the experiments allow precise observation of the influence of liver resection on systemic and local abdominal hemodynamic alterations and oxygen metabolism. Major liver resection is associated with significant and persistent portal hyperperfusion and loss of hepatic arterial buffer response. The correlation of portal hyperperfusion and parameters of liver injury and dysfunction offers a novel therapeutic option to attenuate liver injury after extended liver resection.

A concept for electromagnetic navigated targeting of liver tumors using an angiographic approach

BACKGROUND

The benefits of using navigation technology for percutaneous local ablation of selected hepatocellular carcinoma (HCC) have been shown. Due to additional efforts in the procedural workflow, barriers to introducing navigation systems on a broad clinical level remain high. In this work, initial steps toward a novel concept for simple and precise targeting of HCC are evaluated.

MATERIAL AND METHODS

The proposed technique is based on an angiographic approach using an intrahepatic electromagnetic (EM) reference, for consecutive percutaneous navigated positioning of ablation probes. We evaluated the environmental influence of the angiography suite on EM tracking accuracy, the measurement of a 3 D offset from two 2 D fluoroscopy images, and the accuracy and efficiency of the proposed approach in a porcine liver model.

RESULTS

The C-arm had a major influence on EM tracking accuracy, with an error up to 3.8 mm. The methodology applied for measurement of a 3 D offset from 2 D fluoroscopy images was confirmed to be feasible with a mean error of 0.76 mm. In the porcine liver model experiment, the overall target positioning error (TPE) was 2.0 mm and time for navigated targeting was 17.9 seconds, when using a tracked ablation probe.

CONCLUSIONS

The initial methodology of the proposed technique was confirmed to be feasible, introducing a novel concept for simple and precise navigated targeting of HCC.

Laparoscopic image-based navigation for microwave ablation of liver tumors-A multi-center study

BACKGROUND

Stereotactic navigation technology has been proposed to augment accuracy in targeting intrahepatic lesions for local ablation therapy. This retrospective study evaluated accuracy, efficacy, and safety when using laparoscopic image-guided microwave ablation (LIMA) for malignant liver tumors.

METHODS

All patients treated for malignant liver lesions using LIMA at two European centers between 2013 and 2015 were included for analysis. A landmark-based registration technique was applied for intraoperative tumor localization and positioning of ablation probes. Intraoperative efficiency of the procedure was measured as number of registration attempts and time needed to achieve sufficient registration accuracy. Technical accuracy was assessed as Fiducial Registration Error (FRE). Outcome at 90 days including mortality, postoperative morbidity, rates of incomplete ablations, and early intrahepatic recurrences were reported.

RESULTS

In 34 months, 54 interventions were performed comprising a total of 346 lesions (median lesions per patient 3 (1-25)). Eleven patients had concomitant laparoscopic resections of the liver or the colorectal primary tumor. Median time for registration was 4:38 min (0:26-19:34). Average FRE was 8.1 ± 2.8 mm. Follow-up at 90 days showed one death, 24% grade I/II, and 4% grade IIIa complications. Median length of hospital stay was 2 days (1-11). Early local recurrence was 9% per lesion and 32% per patient. Of these, 63% were successfully re-ablated within 6 months.

CONCLUSIONS

LIMA does not interfere with the intraoperative workflow and results in low complication and early local recurrence rates, even when simultaneously targeting multiple lesions. LIMA may represent a valid therapy option for patients with extensive hepatic disease within a multimodal treatment approach.

Zystische Pankreasläsion – Wie weiter?

Zusammenfassung. Zystische Läsionen im Pankreas werden häufig gefunden, oft primär auf einer CT oder MR Untersuchung des Oberbauches. Primär erlaubt die Anamnese die Unterscheidung zwischen entzündlichen Flüssigkeitsansammlungen oder Pseudozysten nach einer akuten Pankreatitis und neoplastischen zystischen Läsionen, die oft zufällig bei asymptomatischen Patienten diagnostiziert werden. Es gilt dann die Veränderung genauer zu charakterisieren und einer klinischen Entität zuzuordnen, wobei primär zwischen serösen und muzinösen Zysten unterschieden werden muss. Letztere haben ein unterschiedlich hohes Malignitätspotenzial. Eine Endosonographie mit Punktion erlaubt in der Regel die zystische Läsion genauer zu charakterisieren, im Vergleich zur reinen Bildgebung mittels MRT oder CT. Gelingt es eine Läsion genügend zu charakterisieren, empfiehlt sich heute ein Vorgehen entsprechend der 2012 publizierten Konsensus Richtlinien. Insbesondere bei Seitenast IPMN sind die Bücher noch nicht geschlossen, da die Angaben bezüglich Häufigkeit der malignen Veränderungen extrem schwanken und somit der Nutzen einer prophylaktischen Pankreasteilresektion unter Umständen kleiner ist als das Risiko des Eingriffs.

A Novel Ultrasound-Based Registration for Image-Guided Laparoscopic Liver Ablation

Background Patient-to-image registration is a core process of image-guided surgery (IGS) systems. We present a novel registration approach for application in laparoscopic liver surgery, which reconstructs in real time an intraoperative volume of the underlying intrahepatic vessels through an ultrasound (US) sweep process. Methods An existing IGS system for an open liver procedure was adapted, with suitable instrument tracking for laparoscopic equipment. Registration accuracy was evaluated on a realistic phantom by computing the target registration error (TRE) for 5 intrahepatic tumors. The registration work flow was evaluated by computing the time required for performing the registration. Additionally, a scheme for intraoperative accuracy assessment by visual overlay of the US image with preoperative image data was evaluated. Results The proposed registration method achieved an average TRE of 7.2 mm in the left lobe and 9.7 mm in the right lobe. The average time required for performing the registration was 12 minutes. A positive correlation was found between the intraoperative accuracy assessment and the obtained TREs. Conclusions The registration accuracy of the proposed method is adequate for laparoscopic intrahepatic tumor targeting. The presented approach is feasible and fast and may, therefore, not be disruptive to the current surgical work flow.

Percutaneous transluminal angioplasty and stent placement in acute vessel occlusion: evaluation of new methods for interventional stroke treatment

BACKGROUND AND PURPOSE

The major goal of acute ischemic stroke treatment is fast and sufficient recanalization. Percutaneous transluminal balloon angioplasty (PTA) and/or placement of a stent might achieve both by compressing the thrombus at the occlusion site. This study assesses the feasibility, recanalization rate, and complications of the 2 techniques in an animal model.

MATERIALS AND METHODS

Thirty cranial vessels of 7 swine were occluded by injection of radiopaque thrombi. Fifteen vessel occlusions were treated by PTA alone and 15, by placement of a stent and postdilation. Recanalization was documented immediately after treatment and after 1, 2, and 3 hours. Thromboembolic events and dissections were documented.

RESULTS

PTA was significantly faster to perform (mean, 16.6 minutes versus 33.0 minutes for stent placement; P < .001), but the mean recanalization rate after 1 hour was significantly better after stent placement compared with PTA alone (67.5% versus 14.6%, P < .001). Due to the self-expanding force of the stent, vessel diameter further increased with time, whereas the recanalization result after PTA was prone to reocclusion. Besides thromboembolic events related to the passing maneuvers at the occlusion site, no thrombus fragmentation and embolization occurred during balloon inflation or stent deployment. Flow to side branches could also be restored at the occlusion site because it was possible to direct thrombus compression.

CONCLUSIONS

Stent placement and postdilation proved to be much more efficient in terms of acute and short-term vessel recanalization compared with PTA alone.