Oblique approach for CT-guided liver radiofrequency ablation using multiplanar reformation images in hepatocellular carcinoma

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.

Feasibility, safety, and efficacy of artificial carbon dioxide pneumothorax for computed tomography fluoroscopy-guided percutaneous radiofrequency ablation of hepatocellular carcinoma

PURPOSE

To retrospectively assess the feasibility, safety, and efficacy of artificial carbon dioxide (CO₂) pneumothorax for computed tomography (CT) fluoroscopy-guided percutaneous radiofrequency (RF) ablation of hepatocellular carcinoma (HCC).

MATERIALS AND METHODS

This study included 26 sessions of 24 patients in whom the creation of artificial CO₂ pneumothorax was attempted to avoid the transpulmonary route during CT fluoroscopy-guided percutaneous RF ablation of HCC between April 2011 and December 2017. In these 26 sessions, 29 HCCs (mean tumor diameter: 12 mm, range: 6-22 mm) were treated.

RESULTS

Adequate lung displacement after induction of artificial CO₂ pneumothorax was achieved in 23 of the 26 sessions (88.5%). In the remaining three sessions, transpulmonary RF ablation, transthoracic extrapulmonary RF ablation after switching to an artificial pleural effusion procedure, or RF ablation with electrode insertion in the caudal-cranial oblique direction was performed. No major complications were found. Among the 29 treated tumors, one (3.4%) showed local progression, and the other 28 (96.6%) were completely ablated at the last follow-up (mean follow-up period: 39.3 months, range: 7-78 months).

CONCLUSION

Artificial CO₂ pneumothorax for CT fluoroscopy-guided percutaneous RF ablation appeared to be a feasible, safe, and useful therapeutic option for HCC.

Clinical application of ultrasound-guided percutaneous microwave ablation for benign breast lesions: a prospective study

BACKGROUND

Background: Benign breast lesions are the most common diseases in adult women, which have been treated with minimally invasive therapies in recent years. Little is known about the feasibility of Microwave ablation (MWA) for benign breast lesion treatment. The primary aim of this prospective study was to evaluate the safety and efficiency of MWA as a potential therapeutic option for benign breast lesions in a single-center cohort study.

METHODS

Women with possibly benign breast lesions based on an ultrasound (US) assessment who were scheduled to undergo MWA between November 2014 to July 2018 were included in the study. The patients underwent conventional US to measure the size of the lesion, Doppler US to assess the vascularity of the lesion, elastography to evaluate the stiffness of the mass, core needle biopsy of suspicious lesions, contrast-enhanced US to help determine the treatment plan and eventually MWA of the lesion. Lesions were followed at one, three, six, twelve and eighteen months after treatment to with the same imaging modalities.

RESULTS

A total of 314 women aged 17 to 69 years old (mean = 36.9 ± 9.9 years) with 725 benign breast lesions (mean of maximum diameter = 10.86 ± 5.40 mm) were included. The frequency of palpable mass, pain and nipple discharge significantly decreased after treatment. Complete ablation rate was 97.8%, immediately after ablation, which increased to 100% after supplementary ablation of the 15 cases with incomplete ablation. Blood flow classification and lesion's volume also showed a significant decrease, while both volume reduction ratio and disappearance rate significantly increased following treatment. The elasticity score of the lesions showed fluctuations across different follow-up intervals. None of the patients experienced major complications and the 1% who had mild symptoms were successfully treated.

CONCLUSION

MWA treatment is shown to be safe and efficient and has the potential to be considered as an alternative first line treatment for benign breast lesions.

"Direct MPR": A Useful Tool for Oblique CT Fluoroscopy-Assisted Puncture

OBJECTIVE

Conventional multiplanar reconstruction (MPR) imaging can be used as a tool for planning oblique puncture procedures, but it takes a few minutes to reconstruct and is not appropriate for real-time CT fluoroscopy-assisted puncture. Recently, new MPR technology has been used that requires only 8 s and makes it possible to obtain a nearly real-time CT fluoroscopy-assisted oblique puncture. We refer to it as "direct MPR." This is the first clinical report of this technique.

METHODS

Since February 2016, we have performed real-time, CT-guided oblique punctures with this new technology, "direct MPR," using an angio-CT system. We retrospectively reviewed all of our procedures with this new method between February 2016 and June 2016.

RESULTS

We used this technique for 14 cases during the study period. Eight cases were radiofrequency ablation (RFA) for hepatocellular carcinoma (HCC), four were biopsies (lung and adrenal gland), and two were for percutaneous abscess drainage. Six of eight RFA cases were for HCC located immediately below the diaphragm. Both of the drainage cases were abscesses located immediately below the diaphragm. All procedures were successfully completed. The average length of the lesion in the RFA cases was 15.4 ± 3.2 mm. The average length of the lesions in all of the cases was 30.9 ± 31.9 mm. The average craniocaudal angle was 32.5° ± 14.0°.

CONCLUSIONS

Direct MPR makes CT-guided oblique puncture for inaccessible targets, especially those located immediately below diaphragm, easier and safer.

LEVEL OF EVIDENCE

Case series, Level IV.

Current status and prospective of imaging guided radiofrequency ablation in medium to large sized hepatocellular carcinomas

The incidence of liver cancer is high in China and effective treatments are required. Recently, imaging guided radiofrequency ablation (RFA) has become increasingly accepted in treating solid tumors because of minimal invasiveness, easy operation and effectiveness. The outcome of RFA in small liver tumors is even comparable to that of surgery. However, the RFA efficacy in larger ( > 3.0 cm) liver tumors is not satisfactory and recurrence after treatment is common. The development of basic research and RFA device has provided more opportunities for us to treat>3.0 cm liver tumors. The successful ablation of solid tumors relies on three key components, the technology (i.e., the RFA generator and electrodes selected), the biology of the tumor and background tissue, and operator factors. The current development and prospective of the three main elements will be the focus in this review.

Intraprocedural contrast-enhanced ultrasound (CEUS) in liver percutaneous radiofrequency ablation: clinical impact and health technology assessment

OBJECTIVES

To assess the clinical and the economic impacts of intraprocedural use of contrast-enhanced ultrasound (CEUS) in patients undergoing percutaneous radiofrequency ablation for small (<2.5 cm) hepatocellular carcinomas.

METHODS

One hundred and forty-eight hepatocellular carcinomas in 93 patients were treated by percutaneous radiofrequency ablation and immediate assessment by intraprocedural CEUS. Clinical impact, cost effectiveness, and budget, organisational and equity impacts were evaluated and compared with standard treatment without intraprocedural CEUS using the health technology assessment approach.

RESULTS

Intraprocedural CEUS detected incomplete ablation in 34/93 (36.5 %) patients, who underwent additional treatment during the same session. At 24-h, complete ablation was found in 88/93 (94.6 %) patients. Thus, a second session of treatment was spared in 29/93 (31.1 %) patients. Cost-effectiveness analysis revealed an advantage for the use of intraprocedural CEUS in comparison with standard treatment (4,639 vs 6,592) with a 21.9 % reduction of the costs to treat the whole sample. Cost per patient for complete treatment was <euro> 4,609 versus <euro> 5,872 respectively. The introduction of intraprocedural CEUS resulted in a low organisational impact, and in a positive impact on equity

CONCLUSIONS

Intraprocedural use of CEUS has a relevant clinical impact, reducing the number of re-treatments and the related costs per patient.

TEACHING POINTS

• CEUS allows to immediately asses the result of ablation. • Intraprocedural CEUS decreases the number of second ablative sessions. • Intraprocedural CEUS may reduce cost per patient for complete treatment. • Use of intraprocedural CEUS may reduce hospital budget. • Its introduction has low organisational impact, and relevant impact on equity.