Stereotactic Thermal Ablation of Liver Tumors: 3D Planning, Multiple Needle Approach, and Intraprocedural Image Fusion Are the Key to Success—A Narrative Review

Thermal ablation is an emerging, potentially curative approach in treating primary and metastatic liver cancer. Different technologies are available, with radiofrequency ablation (RFA) and microwave ablation (MWA) being the most widely used. Regardless of the technique, destruction of the entire tumor, including an adequate safety margin, is key. In conventional single-probe US- or CT-guided thermal ablation, the creation of such large necrosis zones is often hampered by technical limitations, especially for large tumors (i.e., >2–3 cm). These limitations have been overcome by stereotactic RFA (SRFA): a multiple needle approach with 3D treatment planning and precise stereotactic needle placement combined with intraprocedural image fusion of pre- and post-interventional CT scans for verification of treatment success. With these sophisticated tools and advanced techniques, the spectrum of locally curable liver malignancies can be dramatically increased. Thus, we strongly believe that stereotactic thermal ablation can become a cornerstone in the treatment of liver malignancies, as it offers all the benefits of a minimally invasive method while providing oncological outcomes comparable to surgery. This article provides an overview of current stereotactic techniques for thermal ablation, summarizes the available clinical evidence for this approach, and discusses its advantages.

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

Frontiers in Oncology ◽

10.3389/fonc.2021.623098 ◽

2021 ◽

Vol 11 ◽

Author(s):

Raluca-Maria Sandu ◽

Iwan Paolucci ◽

Simeon J. S. Ruiter ◽

Raphael Sznitman ◽

Koert P. de Jong ◽

...

Keyword(s):

Thermal Ablation ◽

Liver Tumors ◽

Treatment Success ◽

Local Tumor Control ◽

Tumor Control ◽

Complete Coverage ◽

Ct Guided ◽

Ablation Volume ◽

Novel Algorithm ◽

Prospective Database

BackgroundIn 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).MethodsA 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).ResultsApplicability 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.ConclusionThe 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.

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Volumetric assessment of the periablational safety margin after thermal ablation of colorectal liver metastases

European Radiology ◽

10.1007/s00330-020-07579-x ◽

2021 ◽

Author(s):

Gregor Laimer ◽

Nikolai Jaschke ◽

Peter Schullian ◽

Daniel Putzer ◽

Gernot Eberle ◽

...

Keyword(s):

Liver Metastases ◽

Image Fusion ◽

Thermal Ablation ◽

Colorectal Liver Metastases ◽

Treatment Success ◽

Local Treatment ◽

Safety Margin ◽

Ct Scans ◽

Volumetric Assessment ◽

Safety Margins

Abstract Objectives To retrospectively assess the periablational 3D safety margin in patients with colorectal liver metastases (CRLM) referred for stereotactic radiofrequency ablation (RFA) and to evaluate its influence on local treatment success. Methods Forty-five patients (31 males; mean age 64.5 [range 31–87 years]) with 76 CRLM were treated with stereotactic RFA and retrospectively analyzed. Image fusion of pre- and post-interventional contrast-enhanced CT scans using a non-rigid registration software enabled a retrospective assessment of the percentage of predetermined periablational 3D safety margin and CRLM successfully ablated. Periablational safety zones (1–10 mm) and percentage of periablational zone ablated were calculated, analyzed, and compared with subsequent tumor growth to determine an optimal safety margin predictive of local treatment success. Results Mean overall follow-up was 36.1 ± 18.5 months. Nine of 76 CRLMs (11.8%) developed local tumor progression (LTP) with mean time to LTP of 18.3 ± 11.9 months. Overall 1-, 2-, and 3-year cumulative LTP-free survival rates were 98.7%, 90.6%, and 88.6%, respectively. The periablational safety margin assessment proved to be the only independent predictor (p < 0.001) of LTP for all calculated safety margins. The smallest safety margin 100% ablated displaying no LTP was 3 mm, and at least 90% of a 6-mm circumscribed 3D safety margin was required to achieve complete ablation. Conclusions Volumetric assessment of the periablational safety margin can be used as an intraprocedural tool to evaluate local treatment success in patients with CRLM referred to stereotactic RFA. Ablations achieving 100% 3D safety margin of 3 mm and at least 90% 3D safety margin of 6 mm can predict treatment success. Key Points • Volumetric assessment of the periablational safety margin can be used as an intraprocedural tool to evaluate local treatment success following thermal ablation of colorectal liver metastases. • Ablations with 100% 3D periablational safety margin of 3 mm and ablations with at least 90% 3D safety margin of 6 mm can be considered indications of treatment success. • Image fusion of pre- and post-interventional CT scans with the software used in this study is feasible and could represent a useful tool in daily clinical practice.

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Ablation in Primary Liver Tumors

Digestive Disease Interventions ◽

10.1055/s-0039-1691813 ◽

2019 ◽

Vol 03 (02) ◽

pp. 107-116

Author(s):

D. Putzer ◽

P. Schullian ◽

R. Bale

Keyword(s):

Thermal Ablation ◽

Liver Tumors ◽

Large Diameter ◽

Three Dimensional ◽

Safety Margin ◽

Minimal Invasive ◽

R0 Resection ◽

Recurrence Rates ◽

Stereotactic Techniques ◽

Primary Liver Tumors

Minimal invasive thermal ablation techniques have a key role in the treatment regimen of primary liver tumors. These relatively low-risk procedures are established in nonresectable liver tumors and even challenge the surgical approach, which is regarded as first-line treatment in eligible patients.The location and size of the liver tumor, the applied ablation, and guidance technique are crucial for treatment outcome. The confirmation of an adequate ablation zone including sufficient tumor overlap and a safety margin (A0 ablation analogous to R0 resection) is crucial to minimize local recurrence rates and improve survival. A variety of different ablation devices is available. The outcome of conventional computed tomography- or ultrasound-guided thermal ablation in small lesions is well comparable to surgery. However, in liver lesions with large diameter overlapping ablation zones are required to ensure an adequate ablation margin. Therefore, stereotactic techniques in combination with a multiple needle approach, three-dimensional trajectory planning, and image fusion for intraoperative treatment evaluation have been successfully introduced.

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Real-Time US-CT/MRI Image Fusion for Guidance of Thermal Ablation of Liver Tumors Undetectable with US: Results in 295 Cases

CardioVascular and Interventional Radiology ◽

10.1007/s00270-014-0897-y ◽

2014 ◽

Vol 38 (1) ◽

pp. 143-151 ◽

Cited By ~ 104

Author(s):

Giovanni Mauri ◽

Luca Cova ◽

Stefano De Beni ◽

Tiziana Ierace ◽

Tania Tondolo ◽

...

Keyword(s):

Image Fusion ◽

Real Time ◽

Thermal Ablation ◽

Liver Tumors ◽

Mri Image

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Liver Malignancies: CT-Guided Interstitial Brachytherapy in Patients with Unfavorable Lesions for Thermal Ablation

Journal of Vascular and Interventional Radiology ◽

10.1097/01.rvi.0000141343.43441.06 ◽

2004 ◽

Vol 15 (11) ◽

pp. 1279-1286 ◽

Cited By ~ 56

Author(s):

Jens Ricke ◽

Peter Wust ◽

Gero Wieners ◽

Alexander Beck ◽

Chie Hee Cho ◽

...

Keyword(s):

Thermal Ablation ◽

Interstitial Brachytherapy ◽

Liver Malignancies ◽

Ct Guided

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CT-guided interstitial brachytherapy of liver malignancies alone or in combination with thermal ablation: phase I–II results of a novel technique

International Journal of Radiation Oncology*Biology*Physics ◽

10.1016/j.ijrobp.2003.09.024 ◽

2004 ◽

Vol 58 (5) ◽

pp. 1496-1505 ◽

Cited By ~ 81

Author(s):

Jens Ricke ◽

Peter Wust ◽

Anna Stohlmann ◽

Alexander Beck ◽

Chie Hee Cho ◽

...

Keyword(s):

Phase I ◽

Thermal Ablation ◽

Interstitial Brachytherapy ◽

Liver Malignancies ◽

Ct Guided ◽

Novel Technique

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Combining Transarterial Radioembolization (TARE) and CT-Guided High-Dose-Rate Interstitial Brachytherapy (CT-HDRBT): A Retrospective Analysis of Advanced Primary and Secondary Liver Tumor Treatment

Cancers ◽

10.3390/cancers14010072 ◽

2021 ◽

Vol 14 (1) ◽

pp. 72

Author(s):

Florian Nima Fleckenstein ◽

Maximilian Julius Rösel ◽

Maja Krajewska ◽

Timo Alexander Auer ◽

Federico Collettini ◽

...

Keyword(s):

Dose Rate ◽

Liver Tumors ◽

High Dose Rate ◽

Interstitial Brachytherapy ◽

High Dose ◽

Liver Malignancies ◽

Ct Guided ◽

Transarterial Radioembolization ◽

Kaplan Meier ◽

Hazard Ratios

Purpose: Treatment of patients with primary and secondary liver tumors remains challenging. This study analyzes the efficacy and safety of transarterial radioembolization (TARE) combined with CT-guided high-dose-rate interstitial brachytherapy (CT-HDRBT) for the treatment of primary and secondary liver tumors. Patients and Methods: A total of 77 patients (30 female) with various liver malignancies were treated. Primary endpoints were median overall survival (OS) and time to untreatable progression (TTUP). Additionally, subgroup analyses were performed in consideration of diagnosis and procedure sequence. Median OS and TTUP prediction were estimated using Kaplan–Meier analysis and hazard ratios (HR) were calculated using a multivariate Cox proportional hazard model. Results: A total of 115 CT-HDRBT and 96 TARE procedures were performed with no significant complications recorded. Median OS and TTUP were 29.8 (95% CI 18.1–41.4) and 23.8 (95% CI 9.6–37.9) months. Median OS for hepatocellular carcinoma (HCC)-, cholangiocarcinoma carcinoma (CCA) and colorectal cancer (CRC) patients was 29.8, 29.6 and 34.4 months. Patients starting with TARE had a median OS of 26.0 (95% CI 14.5–37.5) compared to 33.7 (95% CI 21.6–45.8) months for patients starting with CT-HDRBT. Hazard ratio of 1.094 per month was shown for patients starting with CT-HDRBT. Conclusion: Combining TARE and CT-HDRBT is effective and safe for the treatment of advanced stage primary and secondary liver tumors. Our data indicate that early TARE during the disease progression may have a positive effect on survival.

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