Local ablation therapy with contrast-enhanced ultrasonography for hepatocellular carcinoma: a practical review

Percutaneous ablation of liver metastases from colorectal cancer: a comparison between the outcomes of ultrasound guidance and CT guidance using propensity score matching

PURPOSE

The aim of this study was to compare the effectiveness and outcomes of percutaneous ablation guided by ultrasonography (US) and computed tomography (CT) in colorectal liver oligometastases (CLOM).

METHODS

This study included patients with CLOM treated with percutaneous ablation from January 2008 to January 2021 in this observational study. Only lesions visualized on both CT and US images were further analyzed according to whether patients' initial ablation treatments utilized US guidance or CT guidance. The Kaplan-Meier method was used to estimate local tumor progression (LTP)-free survival after propensity score matching (PSM). The LTP-free survival and treatment-related outcomes were compared between these two groups.

RESULTS

PSM identified 116 patients from each group, with 269 and 238 lesions in the USguided and CT-guided groups, respectively. US-guided ablation had a shorter average procedure time and lower cost than CT-guided ablation (27.54±12.06 minutes vs. 32.70±13.88 minutes, P=0.003; $2,175.13±618.17 vs. $2,455.49±710.25, P=0.002). For patients >60 years of age, the cumulative LTP rate at 1 year was lower in the US-guided group than in the CT-guided group (17.8% vs. 25.1%, P=0.038). For patients with perivascular liver lesions, the cumulative LTP rate at 1 year was lower in the US-guided group (14.4% vs. 28.2%, P=0.040).

CONCLUSION

For patients whose age is >60 years or who have perivascular liver lesions, USguided ablation is better than CT-guided ablation, with a shorter treatment time and lower costs when both ablation methods are feasible for patients.

Paradigm shift in the treatment options of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is prevalent worldwide with suboptimal therapeutic outcomes. The advancement of therapeutic options and the development of new systemic therapies expand the armamentarium to tackle HCC. Treatment options should be provided based on the hierarchy of efficacy in a multidisciplinary perspective, instead of the traditional stage-guided scheme. In advanced HCC, lenvatinib has a comparable efficacy as sorafenib for the first-line therapy of HCC; while regorafenib, cabozantinib, and ramucirumab have been approved as second-line therapy after the failure of sorafenib. Immune checkpoint inhibitor therapy prolongs response rate and survival and enables long-term cure. Atezolizumab plus bevacizumab is superior to sorafenib as the first-line therapy for advanced HCC. Several emerging regimens by the combination of various systemic therapies are currently under clinical trials. Systemic therapy may be used in the neoadjuvant, adjuvant or even as initial therapy for intermediate-stage HCC. The paradigm shift of HCC treatment will improve patient outcomes.

Contrast-enhanced US of the Liver and Kidney: A Problem-solving Modality

Contrast-enhanced US (CEUS) has an important role as a supplement to CT or MRI in clinical practice. The main established utilizations are in the liver and the kidney. The primary advantages of CEUS compared with contrast-enhanced CT or MRI relate to its superior contrast resolution, real-time continuous scanning, pure intravascular nature, portability, and safety-especially in patients with renal impairment or CT or MRI contrast agent allergy. This article focuses on the use of CEUS in the liver and kidney.

Differential Imaging of Liver Tumors before and after Microwave Ablation with Electrode Displacement Elastography

Liver cancer is a leading cause of cancer-related deaths; however, primary treatment options such as surgical resection and liver transplant may not be viable for many patients. Minimally invasive image-guided microwave ablation (MWA) provides a locally effective treatment option for these patients with an impact comparable to that of surgery for both cancer-specific and overall survival. MWA efficacy is correlated with accurate image guidance; however, conventional modalities such as B-mode ultrasound and computed tomography have limitations. Alternatively, ultrasound elastography has been used to demarcate post-ablation zones, yet has limitations for pre-ablation visualization because of variability in strain contrast between cancer types. This study attempted to characterize both pre-ablation tumors and post-ablation zones using electrode displacement elastography (EDE) for 13 patients with hepatocellular carcinoma or liver metastasis. Typically, MWA ablation margins of 0.5-1.0 cm are desired, which are strongly correlated with treatment efficacy. Our results revealed an average estimated ablation margin inner quartile range of 0.54-1.21 cm with a median value of 0.84 cm. These treatment margins lie within or above the targeted ablative margin, indicating the potential to use EDE for differentiating index tumors and ablated zones during clinical ablations. We also obtained a high correlation between corresponding segmented cross-sectional areas from contrast-enhanced computed tomography, the current clinical gold standard, when compared with EDE strain images, with r2 values of 0.97 and 0.98 for pre- and post-ablation regions.

Use of Contrast-Enhanced Ultrasound in Ablation Therapy of HCC: Planning, Guiding, and Assessing Treatment Response

Contrast-enhanced ultrasonography (CEUS) plays an important role in the management of patients treated with ablation therapies, in the diagnostic, therapeutic and monitoring phases. Compared to contrast-enhanced computed tomography and contrast-enhanced magnetic resonance imaging, CEUS presents several advantages in imaging HCC, including real time imaging capability, high sensitivity for tumor vascularity, absence of renal toxicity, no ionizing radiation, repeatability of injections, good compliance by the patient and low cost. The purpose of this review is to evaluate the role of CEUS in the management of the patients with HCC treated with ablation therapies and describe how in our protocol CEUS is integrated with the other imaging modalities such as contrast-enhanced computed tomography and contrast-enhanced magnetic resonance imaging.

Advanced Techniques in the Percutaneous Ablation of Liver Tumours

Percutaneous ablation is an accepted treatment modality for primary hepatocellular carcinoma (HCC) and liver metastases. The goal of curative ablation is to cause the necrosis of all tumour cells with an adequate margin, akin to surgical resection, while minimising local damage to non-target tissue. Aside from the ablative modality, the proceduralist must decide the most appropriate imaging modality for visualising the tumour and monitoring the ablation zone. The proceduralist may also employ protective measures to minimise injury to non-target organs. This review article discusses the important considerations an interventionalist needs to consider when performing the percutaneous ablation of liver tumours. It covers the different ablative modalities, image guidance, and protective techniques, with an emphasis on new and advanced ablative modalities and adjunctive techniques to optimise results and achieve satisfactory ablation margins.

Contrast-enhanced ultrasound to ultrasound fusion during microwave ablation: feasibility study in a perfused porcine liver model

PURPOSE

To obtain a complete response with thermal ablation, the margin and entire tumor volume must be treated. Real-time ultrasound visualization is limited during ablation due to gas production. This study assesses the feasibility of fusing volumetric contrast-enhanced ultrasound (CEUS), obtained immediately prior to microwave ablation, with real-time CEUS during and following ablation in a machine-perfused porcine liver.

METHODS

Ten, 3-4 cm microwave ablations were performed in five explanted perfused livers. Prior to ablation, microbubbles were injected into the vasculature while an ultrasound sweep across the liver captured a volumetric image during maximum enhancement. This volumetric image was then fused to overlay the real-time ultrasound imaging. Since the perfused livers did not have tumors, a spherical marker circumscribing a target volume was placed on the images. Approximatively, 75% of the total intended circumscribed spherical volume was ablated. Following ablation, a second bolus injection of ultrasound contrast was administered demonstrating continued enhancement of the intentionally non-ablated 25%. A second volumetric image of the post-ablation CEUS was then fused to overlay the real-time ultrasound images for guidance during ablation of the remaining enhancing volume.

RESULTS

Technical success was achieved in 100% of the cases. The pre- and then the post-ablation CEUS volume was fused with real-time imaging during antenna placement for initial and subsequent ablation.

CONCLUSION

CEUS-CEUS fusion during thermal ablation is feasible and greatly improves the workflow. The approach may augment the use of dynamic CEUS for guidance, improving antenna placement, and aiding in the identification and ablation of initial and residual enhancing tissue.

Contrast-enhanced ultrasound of hepatocellular carcinoma: where do we stand?

Contrast-enhanced ultrasound (CEUS) represents a significant breakthrough in ultrasonography (US), and it is being increasingly used for the evaluation of focal liver lesions (FLLs). CEUS is unique in that it allows non-invasive assessment of liver perfusion in real time throughout the vascular phase, which has led to dramatic improvements in the diagnostic accuracy of US in the detection and characterization of FLLs, the choice of therapeutic procedures, and the evaluation of response. Currently, CEUS is included as a part of the suggested diagnostic work-up of FLLs, including in cirrhotic patients with hepatocellular carcinoma, resulting in better patient management and cost-effective delivery of therapy.

Unenhanced magnetic resonance imaging immediately after radiofrequency ablation of liver malignancy: preliminary results

PURPOSE

To assess the accuracy of unenhanced magnetic resonance imaging (MRI) immediately after the percutaneous ultrasound-guided radiofrequency ablation (RFA) of liver malignancy in predicting treatment efficacy at CT follow-up.

MATERIALS AND METHODS

Percutaneous ablation was prospectively performed in 23 liver malignancies (20 hepatocarcinomas and 3 metastases). After the procedure in the same day all patients were studied with unenhanced MRI. The best sequence to detect the coagulative necrosis was visually established. Pre-RFA CT and post-RFA MRI were registered with non-rigid transformation algorithm. Manual segmentation of lesions and ablated areas in pre-RFA CT, post-RFA MRI, and follow-up CT were obtained. Sensitivity, specificity, positive predictive value (PPV), negative predicitve value (NPV), and accuracy of MRI in predicting the correct centering and the complete treatment of the lesion were calculated in respect to the 1-month follow-up CT.

RESULTS

Fat-saturated T1-weighted (fs T1-w) was the sequence in which the best conspicuity of the ablated area was depicted. Coagulative necrosis was hyperintense in fs T1-w sequence in 17/23 (74%). In respect to follow-up CT, MRI predicted the correct centering of the lesions in 19/20 lesions with sensitivity, specificity, PPV, NPV, and accuracy of 100%, 75%, 95%, 100%, and 100%, respectively. MRI predicted the complete treatment of the lesions in 17/17 lesions with sensitivity, specificity, PPV, NPV, and accuracy of 100%.

CONCLUSION

MRI with the single fs T1-w sequence was highly accurate in predicting the treatment efficacy of percutaneous ablation of liver malignancies in comparison to follow-up CT control. Unnecessary CT in case of incomplete treatment can be therefore easily avoided.

Contrast-enhanced ultrasound (CEUS) in abdominal intervention

The introduction of ultrasound contrast agents has rendered contrast-enhanced ultrasound (CEUS) a valuable complementary technique to address clinically significant problems. This pictorial review describes the use of CEUS guidance in abdominal intervention and illustrates such application for a range of clinical indications. Clinical application of CEUS discussed include commonly performed abdominal interventional procedures, such as biopsy, drainage, nephrostomy, biliary intervention, abdominal tumor ablation and its subsequent monitoring, and imaging of vascular complications following abdominal intervention. The purpose of this article is to further familiarize readers with the application of CEUS, particularly its specific strength over alternative imaging modalities, in abdominal intervention.

Contrast-enhanced ultrasound of malignant liver lesions

Contrast-enhanced ultrasound (CEUS) is a safe, relatively inexpensive, and widely available imaging technique using dedicated imaging ultrasound sequences and FDA-approved contrast microbubbles that allow detection and characterization of malignant focal liver lesions with high diagnostic accuracy. CEUS provides dynamic real-time imaging with high spatial and temporal capability, allowing for unique contributions to the already established protocols for diagnosing focal liver lesions using CT and MR imaging. In patients with lesions indeterminate on CT and MRI, CEUS is a helpful problem-solving complementary tool that improves patient management. Furthermore, CEUS assists guidance of liver biopsies and local treatment. Variations of CEUS such as DCE-US and ultrasound molecular imaging are emerging for quantitative monitoring of treatment effects and possible earlier detection of cancer. In this review, basic principles of CEUS techniques and ultrasound contrast agents along with a description of the enhancement patterns of malignant liver lesions are summarized. Also, a discussion of the role of CEUS for treatment guidance and monitoring, intraoperative CEUS, and an outlook on emerging applications is provided.

Percutaneous Liver Tumour Ablation: Image Guidance, Endpoint Assessment, and Quality Control

Liver tumour ablation nowadays represents a routine treatment option for patients with primary and secondary liver tumours. Radiofrequency ablation and microwave ablation are the most widely adopted methods, although novel techniques, such as irreversible electroporation, are quickly working their way up. The percutaneous approach is rapidly gaining popularity because of its minimally invasive character, low complication rate, good efficacy rate, and repeatability. However, matched to partial hepatectomy and open ablations, the issue of ablation site recurrences remains unresolved and necessitates further improvement. For percutaneous liver tumour ablation, several real-time imaging modalities are available to improve tumour visibility, detect surrounding critical structures, guide applicators, monitor treatment effect, and, if necessary, adapt or repeat energy delivery. Known predictors for success are tumour size, location, lesion conspicuity, tumour-free margin, and operator experience. The implementation of reliable endpoints to assess treatment efficacy allows for completion-procedures, either within the same session or within a couple of weeks after the procedure. Although the effect on overall survival may be trivial, (local) progression-free survival will indisputably improve with the implementation of reliable endpoints. This article reviews the available needle navigation techniques, evaluates potential treatment endpoints, and proposes an algorithm for quality control after the procedure.

A20 enhances the radiosensitivity of hepatocellular carcinoma cells to 60Co-γ ionizing radiation

The radioresistance of hepatocellular carcinoma (HCC) cells is a critical obstacle for effectively applying radiotherapy (RT) in HCC treatment. NF-κB, an important transcription factor, can influence critical cell fate decisions by promoting cell survival or anti-apoptosis in response to cell-stress, e.g. chemotherapies or ionizing radiation (IR). A20, also named as tumor necrosis factor α induced protein 3 (TNFAIP3), is a dominant negative regulator of NF-κB pathway and its functions in HCC are largely unknown. The present work aimed to reveal the role of A20 plays in affecting the radiosensitivity of HCC cells. Higher expression of A20 was detected in hepatic non-tumor cell line or clinical specimens compared with HCC cell lines or clinical specimens. A20 decreased the expression of proteins mediating cellular stress/injury response or epithelial-mesenchymal transition (EMT) process. Overexpression of A20 via adenovirus enhanced the effect of ⁶⁰Co-γ ionizing radiation (IR) on HCC cells’ injury, e.g. G2/M arrest or DNA double strands break (DSB). Moreover, A20 also enhanced the in vitro or in vivo survival inhibiting of HCC cells induced by IR. These results reveal the roles of A20 in HCC radiosensitization and overexpression of A20 would be a novel strategy for HCC radiotherapy.

Ultrasound-Guided Percutaneous Microwave Ablation for Hepatocellular Carcinoma in the Caudate Lobe

Treatment for liver tumors in the caudate lobe is challenging because of their location and complex anatomy. This study was intended to evaluate the feasibility, efficacy and tolerability of ultrasound-guided percutaneous microwave (MW) ablation for treating hepatocellular carcinoma (HCC) in the caudate lobe. From December 2011 to May 2015, a total of 20 patients (mean age: 62 ± 11 y) with HCC in the caudate lobe were enrolled in this study. Patient characteristics and tumor features were analyzed. The epigastric approach, intercostal approach and the combination were used in 4, 14 and 2 patients, respectively. Contrast-enhanced ultrasound (CEUS) guidance and temperature monitoring were applied as ancillary techniques. Ethanol injection was performed for tumors adjacent to the inferior vena cava or hepatic hilum. Contrast images were performed to evaluate treatment response after ablation. Technical success, technique efficacy, local tumor progression and complications were documented. Technique efficacy was achieved in 18 patients (18/20, 90%). Two patients received (125)I brachytherapy as palliative therapy for residual tumors that could not be ablated technically after the first ablation. Technical success was achieved in 16 patients (16/20, 80%). In 2 patients, ablation was completed after two sessions. CEUS was applied in 5 patients and temperature monitoring in 2 patients. Eight patients received an ethanol injection during ablation. Eleven patients achieved a minimum 5-mm safety margins. Local tumor progression was detected in 3 patients (16.7%, 3/18) during a median follow-up of 18.4 mo (range: 3-45 mo). Tumors in these 3 patients were all larger than 2.0 cm. No major or minor complications were observed. In conclusion, ultrasound-guided percutaneous microwave ablation combined with CEUS, temperature monitoring, and ethanol injection is a tolerable and relatively effective treatment for HCC in the caudate lobe.