Radiofrequency ablation guided by contrast harmonic sonography using perfluorocarbon microbubbles (Sonazoid) for hepatic malignancies: an initial experience

Diagnostic Accuracy of Sonazoid-Enhanced Ultrasonography for Detection of Liver Metastasis

PURPOSE

To evaluate the potential clinical role and reliability of Sonazoid-enhanced ultrasound (SEUS) as a diagnostic tool for liver metastatic lesions.

METHODS

An extensive literature search was conducted across five electronic databases, PubMed, Scopus, Embase, Cochrane Library, and Web of Science, from their inception up to January 2024 to identify all studies evaluating the use of Sonazoid-enhanced ultrasonography for detecting hepatic metastases. A meta-analysis was performed to assess diagnostic accuracy using the Meta-DiSc 2.0 software.

RESULTS

A total of 31 studies were included, 16 of which were eligible for meta-analysis and diagnostic test accuracy evaluation. A total of 13 studies in the meta-analysis evaluated the diagnostic accuracy of contrast-enhanced ultrasound (CEUS) for 1347 metastatic and 1565 non-metastatic liver lesions. The pooled sensitivity and specificity for CEUS were 0.88 (95% CI: 0.82-0.92) and 0.92 (95% CI: 0.84-0.96), respectively. The combined positive likelihood ratio, negative likelihood ratio, and diagnostic odds ratio were 11.89 (95% CI: 5.42-26.09), 0.12 (95% CI:0.08-0.19), and 91.99 (95% CI: 32.15-263.17), respectively. Additionally, four studies of the meta-analysis assessed the diagnostic performance of contrast-enhanced intraoperative sonography (CE-IOUS) in detecting 664 metastatic and 246 non-metastatic liver lesions. The pooled sensitivity and specificity for CE-IOUS were 0.93 (95% CI: 0.82-0.97) and 0.84 (95% CI: 0.65-0.93), respectively. The aggregated positive likelihood ratio, negative likelihood ratio, and diagnostic odds ratio were calculated as 5.95 (95% CI: 2.32-15.25), 0.07 (95% CI: 0.02-0.24), and 77.68 (95% CI: 10.33-583.86), respectively.

CONCLUSIONS

CE-IOUS and CEUS are reliable approaches for diagnosing liver metastatic lesions. CE-IOUS, in particular, exhibits higher accuracy in identifying liver metastatic lesions, indicating its potential effectiveness in clinical practice.

Contrast-enhanced endoscopic ultrasound for differential diagnosis of autoimmune pancreatitis: a meta-analysis

Background and study aims To assess the diagnostic value of contrast-enhanced endoscopic ultrasound (CE-EUS) for autoimmune pancreatitis and other solid pancreatic masses. Patients and methods A systematic search of PubMed, Embase, and Web of Science was performed from inception to October 2022. We calculated individual and pooled sensitivities and specificities to determine the diagnostic ability of CE-EUS. In addition, we calculated I 2 to test for heterogeneity and explored the source of heterogeneity by meta-regression analysis. Results A total of 472 patients from seven eligible studies were included. The mean sensitivity and specificity of the Bivariate analysis were 0.84 (95% CI 0.71-0.92) and 0.95 (95% CI 0.84-0.99), respectively. The diagnostic advantage ratio was 107.91 (95% confidence interval [CI] 22.22-524.13), and the area under the summary receiver operating characteristics curve was 0.91 (95% CI 0.88-0.93). The overall heterogeneity of the studies is negligible (I 2 =0, 95% CI 0-100). However, notable heterogeneity was observed in the combined specificity ( P <0.01, I 2 =74.82) and diagnostic odds ratio ( P =0.05, I 2 =51.54). The heterogeneity in these aspects could be elucidated through sensitivity analysis. Conclusions Our analysis showed that CE-EUS is useful in identifying autoimmune pancreatitis. However, further large sample size, multicenter, prospective studies are needed to demonstrate its utility.

Tips for Preparing and Practicing Thermal Ablation Therapy of Hepatocellular Carcinoma

Thermal ablation therapy, including radiofrequency ablation (RFA) and microwave ablation (MWA), is considered the optimal locoregional treatment for unresectable early-stage hepatocellular carcinomas (HCCs). Percutaneous image-guided ablation is a minimally invasive treatment that is being increasingly performed because it achieves good clinical outcomes with a lower risk of complications. However, the physics and principles of RFA and MWA markedly differ. Although percutaneous thermal ablation under image guidance may be challenging in HCC cases with limited access or a risk of thermal injury, a number of ablative techniques, each of which may be advantageous and disadvantageous for individual cases, are available. Furthermore, even when a HCC is eligible for ablation based on tumor selection and technical factors, additional patient factors may have an impact on whether it is the appropriate treatment choice. Therefore, a basic understanding of the advantages and limitations of each ablation device and imaging guidance technique, respectively, is important. We herein provide an overview of the basic principles of tissue heating in thermal ablation, clinical and laboratory parameters for ablation therapy, preprocedural management, imaging assessments of responses, and early adverse events. We also discuss associated challenges and how they may be overcome using optimized imaging techniques.

Diagnosis of hepatocellular carcinoma using Sonazoid: a comprehensive review

Sonazoid contrast-enhanced ultrasonography (CEUS) is a promising technique for the detection and diagnosis of focal liver lesions, particularly hepatocellular carcinoma (HCC). Recently, a collaborative effort between the Korean Society of Radiology and Korean Society of Abdominal Radiology resulted in the publication of guidelines for diagnosing HCC using Sonazoid CEUS. These guidelines propose specific criteria for identifying HCC based on the imaging characteristics observed during Sonazoid CEUS. The suggested diagnostic criteria include nonrim arterial phase hyperenhancement, and the presence of late and mild washout, or Kupffer phase washout under the premise that the early or marked washout should not occur during the portal venous phase. These criteria aim to improve the accuracy of HCC diagnosis using Sonazoid CEUS. This review offers a comprehensive overview of Sonazoid CEUS in the context of HCC diagnosis. It covers the fundamental principles of Sonazoid CEUS and its clinical applications, and introduces the recently published guidelines. By providing a summary of this emerging technique, this review contributes to a better understanding of the potential role of Sonazoid CEUS for diagnosing HCC.

No-Touch Radiofrequency Ablation for Early Hepatocellular Carcinoma: 2023 Korean Society of Image-Guided Tumor Ablation Guidelines

Radiofrequency ablation (RFA) has been widely used to manage hepatocellular carcinomas (HCCs) equal to or smaller than 3 cm. No-touch RFA has gained attention and has recently been implemented in local ablation therapy for HCCs, despite its technical complexity, as it provides improved local tumor control compared to conventional tumor-puncturing RFA. This article presents the practice guidelines for performing no-touch RFA for HCCs, which have been endorsed by the Korean Society of Image-Guided Tumor Ablation (KSITA). The guidelines are primarily designed to assist interventional oncologists and address the limitations of conventional tumor-puncturing RFA with describing the fundamental principles, various energy delivery methods, and clinical outcomes of no-touch RFA. The clinical outcomes include technical feasibility, local tumor progression rates, survival outcomes, and potential complications.

Diagnosing Hepatocellular Carcinoma Using Sonazoid Contrast-Enhanced Ultrasonography: 2023 Guidelines From the Korean Society of Radiology and the Korean Society of Abdominal Radiology

Sonazoid, a second-generation ultrasound contrast agent, was introduced for the diagnosis of hepatic nodules. To clarify the issues with Sonazoid contrast-enhanced ultrasonography for the diagnosis of hepatocellular carcinoma (HCC), the Korean Society of Radiology and Korean Society of Abdominal Radiology collaborated on the guidelines. The guidelines are de novo, evidence-based, and selected using an electronic voting system for consensus. These include imaging protocols, diagnostic criteria for HCC, diagnostic value for lesions that are inconclusive on other imaging results, differentiation from non-HCC malignancies, surveillance of HCC, and treatment response after locoregional and systemic treatment for HCC.

Prospective assessment of diagnostic efficacy and safety of SonazoidTM and SonoVue® ultrasound contrast agents in patients with focal liver lesions

OBJECTIVES

To assess the respective diagnostic value of Sonazoid™ and SonoVue® for characterizing FLLs as benign or malignant and the corresponding safety.

METHODS

This prospective Phase 3 study was conducted at 17 centres in China and Korea (May 2014 to April 2015); 424 patients (20 to 80 years) with at least 1 untreated focal liver lesion (FLL) (< 10 cm in diameter) underwent a contrast-enhanced ultrasound (CEUS) examination (218 received Sonazoid of 0.12 μL microbubbles/kg; 206 received SonoVue of 2.4 mL). Three independent blinded readers evaluated pre- and post-contrast images characterising the FLLs as benign or malignant.

RESULTS

Sonazoid-enhanced and SonoVue-enhanced ultrasound provided a statistically significant improvement in specificity for all 3 readers comparing to unenhanced ultrasound (for Sonazoid: p = 0.0093, < 0.0001, 0.0011; for SonoVue: p = 0.002, 0.03, 0.12, respectively). Difference in accuracy improvement between the 2 groups was within the pre-specified non-inferiority margin of 20% for all 3 readers (6.1%, 95% CI: - 5.0 to 17.2; - 7.5%, 95% CI: - 18.4 to 3.5; - 0.3%, 95% CI: - 11.3 to 10.7). The diagnostic confidence level for all 3 readers increased with post-contrast images relative to pre-contrast images. Both contrast agents were well tolerated.

CONCLUSION

Results showed a similar efficacy for Sonazoid™ and SonoVue® in diagnosing FLLs as benign or malignant, and underlined the benefit of CEUS imaging over unenhanced ultrasound imaging in reaching a confident diagnosis without having to refer patients for additional imaging exams.

Image Guidance in Ablation for Hepatocellular Carcinoma: Contrast-Enhanced Ultrasound and Fusion Imaging

The ultrasound (US) imaging technology, including contrast-enhanced US (CEUS) and fusion imaging, has experienced radical improvement, and advancement in technology thus overcoming the problem of poor conspicuous hepatocellular carcinoma (HCC). On CEUS, the presence or absence of enhancement distinguishes the viable portion from the ablative necrotic portion. Using volume data of computed tomography (CT) or magnetic resonance imaging (MRI), fusion imaging enhances the three-dimensional relationship between the liver vasculature and HCC. Therefore, CT/MR-US fusion imaging provides synchronous images of CT/MRI with real-time US, and US-US fusion imaging provides synchronous US images before and after ablation. Moreover, US-US overlay fusion can visualize the ablative margin because it focuses the tumor image onto the ablation zone. Consequently, CEUS and fusion imaging are helpful to identify HCC with little conspicuity, and with more confidence, we can perform ablation therapy. CEUS/fusion imaging guidance has improved the clinical effectiveness of ablation therapy in patients with poor conspicuous HCCs. Therefore; this manuscript reviews the status of CEUS/fusion imaging guidance in ablation therapy of poor conspicuous HCC.

Irreversible electroporation of hepatocellular carcinoma: the role of ultrasonography

Irreversible electroporation (IRE) is a novel form of soft tissue ablation therapy that uses high-current electrical pulses to induce the formation of pores in the cell membrane, leading to cell death. Although outcome data for the ablation of hepatocellular carcinoma (HCC) by IRE are limited, early results are encouraging and may suggest equivalency to the outcomes achieved by thermal ablation methods such as radiofrequency ablation (RFA) and microwave ablation (MWA). However, IRE can be a challenging and very time-consuming procedure compared to RFA and MWA. In this review article, we not only evaluate the efficacy and safety of IRE for the treatment of HCC, but also discuss imaging guidance, ablation monitoring, and endpoint assessment, with a particular focus on ultrasonography.

The AFSUMB Consensus Statements and Recommendations for the Clinical Practice of Contrast-Enhanced Ultrasound using Sonazoid

The first edition of the guidelines for the use of ultrasound contrast agents was published in 2004, dealing with liver applications. The second edition of the guidelines in 2008 reflected changes in the available contrast agents and updated the guidelines for the liver, as well as implementing some nonliver applications. The third edition of the contrast-enhanced ultrasound (CEUS) guidelines was the joint World Federation for Ultrasound in Medicine and Biology-European Federation of Societies for Ultrasound in Medicine and Biology (WFUMB-EFSUMB) venture in conjunction with other regional US societies such as Asian Federation of Societies for Ultrasound in Medicine and Biology, resulting in a simultaneous duplicate on liver CEUS in the official journals of both WFUMB and EFSUMB in 2013. However, no guidelines were described mainly for Sonazoid due to limited clinical experience only in Japan and Korea. The new proposed consensus statements and recommendations provide general advice on the use of Sonazoid and are intended to create standard protocols for the use and administration of Sonazoid in hepatic and pancreatobiliary applications in Asian patients and to improve patient management.

The AFSUMB Consensus Statements and Recommendations for the Clinical Practice of Contrast-Enhanced Ultrasound using Sonazoid

The first edition of the guidelines for the use of ultrasound contrast agents was published in 2004, dealing with liver applications. The second edition of the guidelines in 2008 reflected changes in the available contrast agents and updated the guidelines for the liver, as well as implementing some nonliver applications. The third edition of the contrast-enhanced ultrasound (CEUS) guidelines was the joint World Federation for Ultrasound in Medicine and Biology-European Federation of Societies for Ultrasound in Medicine and Biology (WFUMB-EFSUMB) venture in conjunction with other regional US societies such as Asian Federation of Societies for Ultrasound in Medicine and Biology, resulting in a simultaneous duplicate on liver CEUS in the official journals of both WFUMB and EFSUMB in 2013. However, no guidelines were described mainly for Sonazoid due to limited clinical experience only in Japan and Korea. The new proposed consensus statements and recommendations provide general advice on the use of Sonazoid and are intended to create standard protocols for the use and administration of Sonazoid in hepatic and pancreatobiliary applications in Asian patients and to improve patient management.

Percutaneous Radiofrequency Ablation of Small (1-2 cm) Hepatocellular Carcinomas Inconspicuous on B-Mode Ultrasonographic Imaging: Usefulness of Combined Fusion Imaging with MRI and Contrast-Enhanced Ultrasonography

PURPOSE

To assess usefulness of adding contrast-enhanced ultrasonography (CEUS) to fusion imaging (FI) for percutaneous radiofrequency ablation (RFA) of hepatocellular carcinomas (HCCs) inconspicuous on FI alone. Therapeutic outcomes of RFA under CEUS-added FI guidance for HCCs inconspicuous on FI alone were also evaluated.

METHODS

This prospective study was approved by the institutional review board and informed consent was obtained from all patients. Planning US was performed with FI for 126 patients with a single HCC (1-2 cm) to evaluate the feasibility of RFA by grading lesion conspicuity score using a four-point scale. RFA was performed under CEUS-added FI guidance for HCCs inconspicuous on FI alone. We evaluated how many HCCs initially inconspicuous on FI became conspicuous after adding CEUS. After CEUS-added FI-guided RFA, therapeutic outcomes including rates of technical success, primary technique efficacy, major complications, and local tumor progression were assessed.

RESULTS

After adding CEUS, 90.5% (19/21) of all tumors initially inconspicuous on FI became conspicuous, thus enabling direct targeting for RFA. Technical success and primary technique efficacy rates were 94.7% (18/19) and 100% (19/19), respectively. No major complications were observed after RFA. Cumulative local tumor progression rates after RFA were estimated to be 5.3%, 10.8%, and 10.8% at 1, 2, and 3 years, respectively.

CONCLUSION

Adding CEUS to FI is useful for improving the conspicuity of HCCs inconspicuous on FI alone, thus enabling successful percutaneous RFA with excellent therapeutic outcomes.

Visibility of focal liver lesions: Comparison between kupffer phase of CEUS with sonazoid and hepatobiliary phase of gadoxetic acid-enhanced MRI

BACKGROUND

To investigate the agreement between Kupffer phase of Sonazoid contrast-enhanced sonography (CEUS) and hepatobiliary phase of gadoxetic acid-enhanced MRI in the evaluation of focal liver lesions (FLLs).

METHODS

One hundred fifty-four FLLs in 154 patients who underwent both Sonazoid CEUS and gadoxetic acid-enhanced liver MRI were included in this retrospective study. FLL visibility on the Kupffer-phase images was graded as one (invisible or isoenhancing), two (vaguely visible or vaguely hypoenhancing), or three (clearly visible or clearly hypoenhancing), and that on the hepatobiliary-phase images of MRI was graded as one (invisible or hyper/isointense), two (vaguely visible or weakly hypointense), or three (clearly visible or strongly hypointense). Pairwise comparison of lesion visibility between the two modalities was performed, and intermodality agreement was assessed.

RESULTS

On Kupffer-phase CEUS, 31 (20.1%) lesions were invisible, 17 (11.1%) were vaguely visible, and 106 (68.9%) were clearly visible. On the hepatobiliary-phase MRI, 9 (5.9%) lesions were invisible, 45 (29.2%) were vaguely visible, and 100 (64.9%) were clearly visible. Overall, lesion visibility scores were not significantly different between the two modalities (p = 0.121), but the visibility was significantly better on MRI in smaller lesions. Twenty-eight lesions (18.2%) showed discrepancy in the visibility on CEUS and MRI, and most of the cases (89.7%) were lesions that were invisible on CEUS but visible on MRI.

CONCLUSIONS

The overall visibility of FLLs was comparable between the Kupffer phase of Sonazoid-CEUS and the hepatobiliary-phase images of gadoxetic acid-enhanced MRI, with a discrepancy between the two modalities in 18% of the cases. © 2017 Wiley Periodicals, Inc. J Clin Ultrasound 45:542-550, 2017.

Value of contrast-enhanced sonography of small hepatocellular carcinoma with sonazoid prior to radiofrequency ablation

BACKGROUND

We aimed to determine the value of contrast-enhanced sonography (CEUS) with Sonazoid prior to percutaneous radiofrequency ablation (RFA) of small (<3 cm) hepatocellular carcinoma (HCC).

METHODS

This prospective study was approved by our institutional review board and informed consent was obtained. The following criteria were used for study enrollment: (1) cirrhotic patients with HCCs found by contrast-enhanced CT or Gd-EOB-DTPA-enhanced MRI; (2) a single HCC <3 cm in longest diameter or multinodular HCCs (<3) with each tumor <3 cm in longest diameter; and (3) indeterminate identification of the index tumor from the surrounding cirrhosis-related pseudolesions on conventional US. Percutaneous RFA was performed under the guidance of CEUS with Sonazoid. The value of CEUS in index tumor detection and targeting was compared with that of concurrently performed conventional US.

RESULTS

A total of 38 patients with 43 HCCs (mean size, 1.6 cm; range, 0.5-2.9 cm) were enrolled. The vascular phase of Sonazoid-enhanced ultrasonography showed good tumor enhancement in 30/43 HCCs (70%). The Kupffer phase increased lesion conspicuity and operator's diagnostic confidence in 29 patients with 31 HCCs (31/43, 72%) compared with conventional US.

CONCLUSIONS

CEUS with Sonazoid is useful for detection and targeting of small HCC prior to RFA. © 2017 Wiley Periodicals, Inc. J Clin Ultrasound 45:383-390, 2017.

Long-term survival of hepatocellular carcinoma after percutaneous radiofrequency ablation guided by ultrasound

Background

The risk factors for recurrence and death after radiofrequency ablation (RFA) for hepatocellular carcinoma (HCC) remain poorly known. This study was aimed to study the 10-year overall survival (OS) of HCC treated by ultrasound (US)-guided RFA and the risk factors for recurrence and death.

Methods

Between June 2005 and June 2016, 1000 patients with HCC treated by US-guided RFA at 4 hospitals in China; among them, 525 patients met the criteria for radical ablation and 410 had high AFP levels before RFA treatment. Clinical and biochemical factors were tested for association with recurrence and survival. Patients were divided into the recurrence (n = 348) and no recurrence groups (n = 62).

Results

The 5- and 10-year survival rates were 66 and 35%, respectively. Tumor size (HR = 1.36, 95% CI 1.12–1.65), albumin levels (HR = 0.76, 95% CI 0.65–0.91), prothrombin time (HR = 2.18, 95% CI 1.54–3.10), and α-fetoprotein levels (HR = 1.13, 95% CI 1.00–1.26) were independently associated with mortality after RFA for HCC. Tumor size (HR = 1.27, 95% CI: 1.15–1.40), HBV-DNA (HR = 7.70, 95% CI 3.57–16.63), AFP levels before treatment (HR = 2.172, 95% CI 1.256–3.756, P = 0.006), and AFP response (HR = 4.722, 95% CI 1.053–21.184, P = 0.0427) were independently associated with the risk of recurrence of HCC after RFA. The median survival of the patients with and without recurrence after RFA was 54 (95% CI 45–58) and 62 (95% CI 48–80) months, respectively (log-rank, P = 0.04).

Conclusions

Tumor size, albumin, prothrombin time, and α-fetoprotein levels were independently associated with mortality after US-guided RFA for HCC, while tumor size and HBV-DNA were independently associated with recurrence. Patients with recurrence had a poorer survival compared with those without.

Sonazoid-enhanced ultrasonography guidance improves the quality of pathological diagnosis in the biopsy of focal hepatic lesions

BACKGROUND/AIM

Contrast-enhanced ultrasonography (US) has improved the detection and characterization of focal hepatic lesions. Recently, the importance of obtaining high-quality samples in the biopsy of hepatic lesions has been increasing not only in the field of pathological diagnosis but also in molecular analysis for predicting the effectiveness of anticancer agents and molecular targeted drugs. We evaluated the utility of Sonazoid-enhanced ultrasonography (SEUS) in guiding percutaneous biopsy of focal hepatic lesions by comparing the results of histopathological diagnosis between B-mode US and SEUS guidance.

METHODS AND MATERIALS

This retrospective study examined 121 focal hepatic lesions in 108 patients (mean age: 63.8 years) referred for US-guided percutaneous biopsy. The technical success rate was defined as the percentage of the lesions diagnosed clearly at the initial biopsy.

RESULTS

Among 121 lesions, 56 lesions were subjected to biopsy with B-mode US guidance whereas 65 were subjected to SEUS guidance. The technical success rate was significantly higher under SEUS guidance than under B-mode US guidance (92.3 vs. 76.8%, respectively, P<0.05). When biopsies were performed to diagnose or rule out malignancy in indeterminate lesions, the technical success rate was also significantly higher under SEUS guidance than under B-mode US guidance (100 vs. 73.9%, respectively, P<0.05). SEUS guidance resulted in a significantly higher rate of successful single-puncture attempts compared with B-mode US guidance (55.4 vs. 35.7%, respectively, P<0.05).

CONCLUSION

SEUS guidance is recommended for more accurate localization of suitable hepatic lesion biopsy areas as it increases conspicuity and differentiates viable areas from denaturalization or necrosis.

US-US Fusion Imaging in Radiofrequency Ablation for Liver Metastases

OBJECTIVE

Radiofrequency ablation (RFA) induces gas bubbles in ablation zones, and the ablative margin cannot be evaluated accurately on ultrasound (US) during and immediately after RFA. This study assessed the usefulness of US-US fusion imaging to visualize the ablative margin of RFA for liver metastasis.

METHODS

RFA guided by US-US fusion imaging was performed on 12 targeted tumors in 10 patients. Secondary hepatic malignancies included patients with colorectal cancer (n = 4), breast cancer (n = 2), lung cancer (n = 1), gastrointestinal stromal tumor (n = 1), pancreatic neuroendocrine tumor (n = 1), and adrenocortical carcinoma (n = 1). The maximal diameter of the tumors ranged from 0.8 to 4.0 cm (mean ± SD 1.6 ± 0.9 cm).

RESULTS

The mean number of electrode insertions was 1.6 per session (range 1-3). Technically, effective ablation was achieved in a single session in all patients, and safety ablative margins were confirmed on contrast-enhanced CT for early assessment of tumor response. There were no serious adverse events or procedure-related complications. During the follow-up period (median 220 days, range 31-417 days), none of the patients showed local tumor progression.

CONCLUSION

US-US fusion imaging could show the tumor images before ablation and the ablative area on US in real time. The image overlay of US-US fusion imaging made it possible to evaluate the ablative margin three dimensionally according to the US probe action. Therefore, US-US fusion imaging can contribute to RFA therapy with a safety margin, that is, the so-called precise RFA.

Effect of parenchymal uptake of perfluorobutane microbubbles (Sonazoid(®) ) on radiofrequency ablation of the liver: in vivo experimental study

BACKGROUND & AIMS

To investigate the differences in mechanical effects and ablation zone between radiofrequency (RF) ablation with and without Sonazoid uptake in an in vivo rabbit liver model.

METHODS

Our study was approved by the Institutional Animal Care and Use Committee. Twenty-five rabbits were randomly allotted to one of five ablation durations (i.e., 1, 2, 3, 6 and 12 min). For each rabbit, RF ablation was performed twice, before and 10 min after Sonazoid administration (i.e. control group vs. Sonazoid group), using a 1-cm internally cooled electrode (40W) equipped with a parallelly fixed pressure-monitoring device. During ablation, a 'popping' sound was perceived and recorded along with tissue pressure changes and RF ablation parameters. Then, the ablation volume and microscopic changes were compared.

RESULTS

Popping sounds were more frequently perceived in the control group (21/25 vs. 1/25, P < 0.001). The time to first pressure peak was shorter in the Sonazoid group (22.3 ± 1.1 s vs. 46.3 ± 4.4 s, P < 0.001) with similar pressures (39.8 ± 4.2 mmHg vs. 35.6 ± 4.1 mmHg, P = 0.350). Time to first roll-off and mean power output were significantly less in the Sonazoid group (17.6 ± 1.2 s vs. 71.2 ± 8.2 s, P < 0.001; 9.4 ± 0.3 W vs. 12.8 ± 0.5 W, P < 0.001). Consequently, the Sonazoid group had lower total energy and ablation volumes for all durations. Microscopically, the control group showed larger conflu-ent disruptions, whereas the Sonazoid group showed many smaller disruptions scattered throughout the ablation zones.

CONCLUSIONS

Radiofrequency ablation after Sonazoid uptake induces a smaller ablation zone than conventional RF ablation. However, it appears to ablate the liver tissue with less mechanical effects.

Role of contrast-enhanced ultrasonography with Sonazoid for hepatocellular carcinoma: evidence from a 10-year experience

Hepatocellular carcinoma (HCC) represents primary liver cancer. Because the development of HCC limits the prognosis as well as the quality of life of the patients, its management should be properly conducted based on an accurate diagnosis. The liver is the major target organ of ultrasound (US), which is the simple, non-invasive, and real-time imaging method available worldwide. Microbubble-based contrast agents are safe and reliable and have become popular, which has resulted in the improvement of diagnostic performances of US due to the increased detectability of the peripheral blood flow. Sonazoid (GE Healthcare, Waukesha, WI, USA), a second-generation contrast agent, shows the unique property of accumulation in the liver and spleen. Contrast-enhanced US with Sonazoid is now one of the most frequently used modalities in the practical management of liver tumors, including the detection and characterization of the nodule, evaluation of the effects of non-surgical treatment, intraoperative support, and post-treatment surveillance. This article reviews the 10-year evidence for contrast-enhanced US with Sonazoid in the practical management of HCC.

Assessment of a needle-tracking system for bipolar radiofrequency ablation

PURPOSE

The purpose of this study was to assess the accuracy and efficacy of a needle-tracking system in phantom and clinical studies using bipolar electrodes.

METHODS

To observe the tip of the electrode, a needle-tracking system with a volume navigation system was used. In the phantom study, the electrode was inserted at various angles and the error was verified. In the clinical study, 21 nodules close to extrahepatic organs or major vessels were enrolled between May and October 2014. After puncturing with the needle-tracking system, computed tomography (CT) was performed. The distances between the electrode tip and extrahepatic organs or major vessels were measured on both B-mode ultrasound (US) and CT. By comparing these distances, the accuracy of this system was evaluated.

RESULTS

In the phantom study, the deviation between the tip of the electrode and the virtual tip of the electrode was analyzed. The median values were within 2 mm at each puncture angle. In the clinical study, the difference between B-mode US and CT was less (mean value 1.17 ± 1.76 mm; range 0-3.5 mm).

CONCLUSION

The needle-tracking system is an accurate and useful system for bipolar radiofrequency ablation.

The Role of Contrast-Enhanced Ultrasound in Guiding Radiofrequency Ablation of Hepatocellular Carcinoma

Purpose

The objective of the study was to determine the efficacy of contrast-enhanced ultrasound (CEUS) using ultrasound (US)-specific microbubbles in guiding radiofrequency ablation (RFA) of hepatocellular carcinoma (HCC).

Methods

A retrospective analysis of 50 patients with HCC treated with CEUS guided RFA using perflutren at our institution was performed. CEUS images were first compared to B-mode US images performed at the same RFA session to determine the ability of CEUS to increase the conspicuity of lesions. A qualitative score (1 = poor, 2 = fair, 3 = excellent) was used to grade the ability to visualize the lesions. The preprocedure CEUS images were then evaluated using the most recent prior contrast enhanced computed tomography (CT) or magnetic resonance imaging (MRI). The efficacy of the treatment was evaluated with short-term follow-up imaging (median 1 month) for presence of residual or recurrent disease.

Results

CEUS allows at least fair visualization (score ≥2) in 78% (reader 1) and 80% (reader 2) of the lesions not visualized by B-mode US, and 50% (reader 1) and 42% (reader 2) of the lesions poorly visualized by B-mode US. Lesion appearances on CEUS are largely concordant with those on CT or MRI: 88% for reader 1, 96% for reader 2. With CEUS-guided RFA, complete response was achieved in the vast majority of the lesions at short-term follow-up: 82% for reader 1, 94% for reader 2.

Conclusions

CEUS increases the conspicuity and provides better characterization of hypervascular HCC that are either not seen or poorly seen on B-mode US, and CEUS provides real-time guidance of RFA with good short-term treatment responses.

Real-time contrast-enhanced sonographically guided biopsy or radiofrequency ablation of focal liver lesions using perflurobutane microbubbles (sonazoid): value of Kupffer-phase imaging

OBJECTIVES

To evaluate the utility of Kupffer-phase imaging by real-time contrast-enhanced sonography using the perflurobutane microbubble contrast agent Sonazoid (GE Healthcare, Oslo, Norway) in guiding biopsy or radiofrequency (RF) ablation of focal liver lesions.

METHODS

A total of 75 patients (mean age, 59.7 years) who were referred for percutaneous biopsy (n = 42) or RF ablation (n = 33) were included in the study. Grayscale sonography and contrast-enhanced sonography using Sonazoid were performed in all patients before the procedure. The conspicuity of each targeted liver lesion on grayscale sonography, vascular-phase contrast-enhanced sonography, and Kupffer-phase contrast-enhanced sonography was graded using a 5-point scale. Lesion detection rates were calculated, and the conspicuity of the lesions among the imaging modalities was compared. The technical success of the procedures was also assessed.

RESULTS

The procedures were conducted in 66 patients (biopsy in 41 and RF ablation in 25) under real-time guidance by Kupffer-phase contrast-enhanced sonography. Lesion detection rates were 77.3% (58 of 75), 84.0% (63 of 75), and 92.0% (69 of 75) on grayscale sonography, vascular-phase contrast-enhanced sonography, and Kupffer-phase contrast-enhanced sonography, respectively, and were significantly different among the 3 modalities (P= .034). Overall, lesion conspicuity was significantly increased on vascular-phase and Kupffer-phase contrast-enhanced sonography compared to grayscale sonography (P < .001). Technical success rates for the procedures were 95.2% (40 of 42) for biopsy and 69.7% (23 of 33) for RF ablation.

CONCLUSIONS

Kupffer-phase imaging by contrast-enhanced sonography using Sonazoid increases the conspicuity of the liver lesions compared to grayscale sonography, and it is useful for real-time guidance of percutaneous biopsy or RF ablation of focal liver lesions.

Combination guidance of contrast-enhanced US and fusion imaging in radiofrequency ablation for hepatocellular carcinoma with poor conspicuity on contrast-enhanced US/fusion imaging

PURPOSE

The purpose of this study was to evaluate the usefulness of the combination guidance of contrast-enhanced US (CEUS) and fusion imaging in radiofrequency ablation (RFA) for hepatocellular carcinoma (HCC) with poor conspicuity on B-mode US and CEUS/fusion imaging.

MATERIALS AND METHODS

We conducted a retrospective cohort study, which included 356 patients with 556 HCCs that were inconspicuous on B-mode US. A total of 192 patients with 344 HCCs, 123 patients with 155 HCCs, and 37 patients with 57 HCCs underwent RFA under CEUS guidance, fusion imaging guidance, and the combination of CEUS and fusion imaging guidance.

RESULTS

The average number of treatment sessions was 1.1 (range: 1-2) in the CEUS guidance group, 1.1 (range: 1-2) in the fusion imaging guidance group, and 1.1 (range: 1-3) in the combination of CEUS and fusion imaging guidance group. Treatment analysis did not reveal significantly more RFA treatment sessions in the combination guidance group than in the other groups (p = 0.97, Student's t test). During the follow-up period (1.1-85.3 months, mean ± SD, 43.2 ± 59.5), the 3-year local tumor progression rates were 4.9, 7.2, and 5.9% in the CEUS guidance group, the fusion imaging guidance group, and the combination guidance group, respectively (p = 0.84, log-rank test).

CONCLUSION

In spite of selection bias, session frequency and local tumor progression were not different under the combination guidance with CEUS and fusion imaging in RFA. The combination of fusion imaging and CEUS guidance in RFA therapy is an effective treatment for HCC with poor conspicuity on B-mode US and CEUS/fusion imaging.

Ultrasound fusion imaging of hepatocellular carcinoma: a review of current evidence

With advances in technology, imaging techniques that entail fusion of sonography and CT or MRI have been introduced in clinical practice. Ultrasound fusion imaging provides CT or MRI cross-sectional multiplanar images that correspond to the sonographic images, and fusion imaging of B-mode sonography and CT or MRI can be displayed simultaneously and in real time according to the angle of the transducer. Ultrasound fusion imaging helps us understand the three-dimensional relationship between the liver vasculature and tumors, and can detect small liver tumors with poor conspicuity. This fusion imaging is attracting the attention of operators who perform radiofrequency ablation (RFA) for the treatment of hepatic malignancies because this real-time, multimodality comparison can increase monitoring and targeting confidence during the procedure. When RFA with fusion imaging was performed on small hepatocellular carcinomas (HCCs) with poor conspicuity, it was reported that the rates of technical success and local tumor progression were 94.4-100% and 0-8.3%. However, there have been no studies comparing fusion imaging guidance and contrast-enhanced sonography, CT or MRI guidance in ablation. Fusion imaging-guided RFA has proved to be effective for HCCs that are poorly defined on not only conventional B-mode sonography but also contrast-enhanced sonography. In addition, fusion imaging could be useful to assess the treatment response of RFA because of three-dimensional information. Here, we give an overview of the current status of ultrasound fusion imaging for clinical application in the liver.

The gross classification of hepatocellular carcinoma: usefulness of contrast-enhanced US

BACKGROUND

This study investigated the usefulness of postvascular images of contrast-enhanced ultrasonography (CE-US) in the gross classification of hepatocellular carcinoma (HCC) in comparison with contrast-enhanced CT (CE-CT) findings.

METHODS

This is a prospective study with consecutive HCC patients who had both CE-US and CE-CT prior to surgical resection. Fifty-one patients (32 men, 19 women; mean age, 68.9 years) with 61 HCCs were enrolled. The maximal diameters of all tumors ranged from 1.0 to 5.0 cm (mean ± SD, 2.5 cm ± 1.1). Weighted kappa statistics were used to assess the agreement of the sonographic or CT findings versus the results of macroscopic configurations.

RESULTS

Thirty-nine tumors were macroscopically diagnosed as simple nodule type; 19 tumors were macroscopically diagnosed as simple nodular type with extranodular growth, and 3 were macroscopically diagnosed as confluent multinodular type from the resected specimen. The diagnostic accuracy was 86.9% (53/61) for CE-US and 65.6% (40/61) for CE-CT. The differences in accuracy between CE-US and CE-CT were statistically significant (McNemar; p = 0.007). Agreement analysis between gross classification using CE-US and final macroscopic results gave a kappa value of 0.74 (95% CI: 0.65–0.82), which was considered a good agreement. On the other hand, kappa coefficient value was 0.38 (95% CI: 0.28–0.48) between gross classification using CE-CT and final macroscopic results.

CONCLUSIONS

CE-US is a more reliable tool than CE-CT to evaluate the gross type of HCC than CE-CT. Accurate gross classification using imaging is considered to be essential for the determination of the correct treatment strategy and the estimates of the patients' prognosis.

Pretreatment evaluation with contrast-enhanced ultrasonography for percutaneous radiofrequency ablation of hepatocellular carcinomas with poor conspicuity on conventional ultrasonography

Objective

To determine whether pretreatment evaluation with contrast-enhanced ultrasonography (CEUS) is effective for percutaneous radiofrequency ablation (RFA) of hepatocellular carcinoma (HCC) with poor conspicuity on conventional ultrasonography (US).

Materials and Methods

This retrospective study was approved by the institutional review board and informed consent was waived. From June 2008 to July 2011, 82 patients having HCCs (1.2 ± 0.4 cm) with poor conspicuity on planning US for RFA were evaluated with CEUS prior to percutaneous RFA. We analyzed our database, radiologic reports, and US images in order to determine whether the location of HCC candidates on planning US coincide with that on CEUS. To avoid incomplete ablation, percutaneous RFA was performed only when HCC nodules were identified on CEUS. The rate of technical success was assessed. The cumulative rate of local tumor progression was estimated with the use of the Kaplan-Meier method (mean follow-up: 24.0 ± 13.0 months).

Results

Among 82 patients, 73 (89%) HCCs were identified on CEUS, whereas 9 (11%) were not. Of 73 identifiable HCCs on CEUS, the location of HCC on planning US corresponded with that on CEUS in 64 (87.7%), whereas the location did not correspond in 9 (12.3%) HCCs. Technical success was achieved for all 73 identifiable HCCs on CEUS in a single (n = 72) or two (n = 1) RFA sessions. Cumulative rates of local tumor progression were estimated as 1.9% and 15.4% at 1 and 3 years, respectively.

Conclusion

Pretreatment evaluation with CEUS is effective for percutaneous RFA of HCCs with poor conspicuity on conventional US.

Contrast-enhanced ultrasound in the preoperative, intraoperative and postoperative assessment of liver lesions

The use of contrast agents (CA) with liver ultrasound (US) has gained recently an established role for the diagnosis of various hepatic diseases due to their safety, high versatility and low costs (contrast-enhanced ultrasound: CEUS). The purpose of this review is to provide a state-of-the-art summary of the available evidence for their use in the characterization of focal liver lesions. A published work search was conducted for all preclinical and clinical studies involving CA on hepatic US imaging. CEUS increases the sensitivity for lesion detection and the specificity to differentiate between benign and malignant diseases due to the enhanced visualization of the tumor microcirculation. Results achieved seem at least equivalent to those of spiral computed tomography or magnetic resonance imaging. The association of CA with intraoperative ultrasound has changed the surgical approach in 25% of patients and guarantees complete ablations by a single session in most of them. CEUS provides detailed information about tumor vasculature, improves the preoperative characterization and therefore the therapeutic strategy, and can evaluate the intraoperative completeness of the ablation.

Advanced ultrasonography technologies to assess the effects of radiofrequency ablation on hepatocellular carcinoma

Background

Radiofrequency ablation (RFA) is a curative therapy for hepatocellular carcinoma (HCC). In RFA, ultrasonography (US) is most commonly used to guide tumor puncture, while its effects are assessed using dynamic computed tomography or magnetic resonance. The differences in modalities used for RFA and assessment of its effects complicate RFA. We developed a method for assessing the effects of RFA on HCC by combining contrast-enhanced (CE) US and real-time virtual sonography with three-dimensional US data.

Patients and methods

Before RFA, we performed a sweep scan of the target HCC nodule and the surrounding hepatic parenchyma to generate three-dimensional US data. After RFA, we synchronized multi-planar reconstruction images derived from stored three-dimensional US data with real-time US images on the same US monitor and performed CEUS and real-time virtual sonography. Using a marking function, we drew a sphere marker along the target HCC nodule contour on pre-treatment US- multi-planar reconstruction images so that the automatically synchronized sphere marker represented the original HCC nodule contour on post-treatment real-time CEUS images. Ablation was considered sufficient when an avascular area with a margin of several millimeters in all directions surrounded the sphere marker on CEUS.

Results

This method was feasible and useful for assessing therapeutic effects in 13 consecutive patients with HCC who underwent RFA. In 2 patients who underwent multiple sessions of RFA, HCC-nodule portions requiring additional RFA were easily identified on US images.

Conclusions

This method using advanced US technologies will facilitate assessment of the effects of RFA on HCC.

Percutaneous radiofrequency ablation guided by contrast-enhanced ultrasound in treatment of metastatic hepatocellular carcinoma after liver transplantation

This study evaluated the advantages and applications of contrast-enhanced ultrasound (CEUS)-supported percutaneous radiofrequency ablation (RFA) in the treatment of metastatic hepatocellular carcinoma after liver transplantation, based on clinical details. CEUS-supported percutaneous RFA was adopted to treat 12 patients with hepatic metastatic carcinomas after liver transplantation. The diameters of the metastatic carcinomas varied from 1 cm to 5 cm, and the foci were discovered after 3 months to 12 months. Each focus was diagnosed and localised by CEUS for RFA once or twice. Curative effects were evaluated by CEUS or contrast-enhanced CT after the treatment. The re-examination results at 2 weeks post-treatment showed that the foci of 11 patients were ablated completely, whereas one patient with the largest focus required retreatment by RFA because of a partial residue. No local recurrence was found one month later in the re-examination. CEUS-supported percutaneous RFA in the treatment of hepatic metastatic carcinoma after liver transplantation has the advantages of accurate localisation, good efficacy, easy operation, and minimal invasion without any complications. Therefore, it can be recommended as the preferred therapy for hepatic metastatic carcinoma after liver transplantation.

Role of contrast-enhanced ultrasonography in percutaneous radiofrequency ablation of liver metastases and efficacy evaluation

OBJECTIVE

To retrospectively investigate the role of contrast-enhanced ultrasonography (CEUS) in percutaneous radiofrequency ablation (RFA) in patients with liver metastases and evaluate the therapeutic efficacy of RFA assisted by CEUS.

METHODS

From May 2004 to September 2010, 136 patients with 219 liver metastatic lesions received CEUS examination 1 h before RFA (CEUS group), and other 126 patients with 216 lesions without CEUS examination in the earlier period were served as a historical control group. The mean tumor size was 3.2 cm and the mean tumor number was 1.6 in the CEUS group, while 3.4 cm and 1.7 in the control group, respectively (P>0.05). The clinical characteristics, recurrence results and survival outcomes were compared between two groups.

RESULTS

In the CEUS group, two isoechoic tumors were not demonstrated on unenhanced ultrasonography (US), and 63 (47%) of 134 tumors examined with CEUS were 0.3 cm larger than with unenhanced US. Furthermore, in 18.4% of 136 patients, additional 1-3 tumors were detected on CEUS. The CEUS group showed higher early tumor necrosis and lower intrahepatic recurrence than the control group. The 3-year overall survival (OS) rate and the 3-year local recurrence-free survival (LRFS) rate in the CEUS group were 50.1% and 38.3%, in contrast to 25.3% and 19.3% in the control group, respectively (P=0.002 and P<0.001).

CONCLUSIONS

CEUS provides important information for RFA treatment in patients with liver metastases and better therapeutic effect could be attained.

Local ablation for hepatocellular carcinoma in taiwan

Hepatocellular carcinoma (HCC) is the second commonest cancer in Taiwan. The national surveillance program can detect HCC in its early stages, and various curative modalities (including surgical resection, orthotopic liver transplantation, and local ablation) are employed for the treatment of small HCC. Local ablation therapies are currently advocated for early-stage HCC that is unresectable because of co-morbidities, the need to preserve liver function, or refusal of resection. Among the various local ablation therapies, the most commonly used modalities include percutaneous ethanol injection and radiofrequency ablation (RFA); percutaneous acetic acid injection and microwave ablation are used less often. RFA is more commonly employed than other local ablative modalities in Taiwan because the technique is highly effective, minimally invasive, and requires fewer sessions. RFA is therefore advocated in Taiwan as the first-line curative therapy for unresectable HCC or even for resectable HCC. However, current RFA procedures are less effective against tumors that are in high-risk or difficult-to-ablate locations, are poorly visualized on ultrasonography (US), or are large. Recent advancements in RFA in Taiwan can resolve these issues by the creation of artificial ascites or pleural effusion, application of real-time virtual US assistance, use of combination therapy before RFA, or use of switching RF controllers with multiple electrodes. This review article provides updates on the clinical outcomes and advances in local ablative modalities (mostly RFA) for HCC in Taiwan.

Thermal tumor ablation therapy for colorectal cancer hepatic metastasis

Surgical resection for colorectal hepatic metastases (CRHM) is the preferred treatment for suitable candidates, and the only potentially curative modality. However, due to various limitations, the majority of patients with CRHM are not candidates for liver resection. In recent years, there has been an increasing interest in the role of thermal tumor ablation (TTA) as a component of combined resection-ablation strategies, staged hepatic resections, or as standalone adjunct treatment for patients with CRHM. Thus, ablative approaches have expanded the group of patients with CRHM that may benefit from liver-directed treatment strategies.

Heterogeneous staining in the liver parenchyma after the injection of perflubutane microbubble contrast agent

This study aimed to characterize the features of heterogeneous staining in the liver after injection of perflubutane microbubble agent (Sonazoid(TM), 0.0075 mL/kg). Digitized hepatic contrast sonograms from 906 subjects were reviewed to assess time-related changes in heterogeneous staining and the possible association between this effect and the clinical backgrounds was analyzed. Heterogeneous staining was found in seven subjects (0.77%) on 15-min phase sonograms. The staining initially appeared as hyper-enhanced circular spots in the liver 10 min or later after the agent injection. The number of spots increased gradually with unequally-spaced distribution. Although the staining pattern did not improve during the examination, there were no abnormal findings in vital signs or symptoms on the day and blood test results or sonograms on the following day. Heterogeneous staining is a side effect that impedes ultrasound examination. However, at present, the precise causes and underlying mechanisms of this event are unknown.

[Contrast-enhanced sonography. Therapy control of radiofrequency ablation and transarterial chemoembolization of hepatocellular carcinoma]

Due to the imaging of dynamic perfusion, hepatocellular carcinoma can be detected with a sensitivity of >90% using contrast-enhanced sonography. The characterization of liver tumors with contrast-enhanced sonography is comparable to the diagnostic accuracy of contrast-enhanced computed tomography. The dynamic detection of microvascularization with contrast-enhanced sonography allows the differentiation between vascularized tumors and non-vascularized necrotic lesions before, during and after transarterial chemoembolization or percutaneous radiofrequency ablation. Image fusion with volume navigation can be useful in the followup control.

Efficacy of fusion imaging combining sonography and hepatobiliary phase MRI with Gd-EOB-DTPA to detect small hepatocellular carcinoma

OBJECTIVE

We evaluated the efficacy of fusion imaging that fuses conventional sonography images with hepatobiliary phase contrast-enhanced MR images obtained with gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid (Gd-EOB-DTPA) as the reference image for the detection of hepatocellular carcinomas (HCCs).

SUBJECTS AND METHODS

Eighty-seven HCCs with a maximum diameter of between 1 and 3 cm at the time of diagnosis were enrolled in this prospective study. We compared the detection rates of HCCs using three sonography modalities: conventional sonography, late phase of contrast-enhanced sonography with Sonazoid, and fusion imaging combining conventional sonography and the hepatobiliary phase of contrast-enhanced MRI with Gd-EOB-DTPA as the reference image. The comparisons were made using the McNemar test.

RESULTS

The detection rate of HCCs using fusion imaging (98%, 85/87) was significantly higher than the detection rates using conventional sonography (76%, 66/87) and contrast-enhanced sonography (83%, 72/87) (p<0.01, for both). For small HCCs (maximum diameter, 1-2 cm), the detection rate using fusion imaging (97%, 59/61) was also significantly higher than those using conventional sonography (66%, 40/61) and contrast-enhanced sonography (80%, 49/61) (p<0.01, for both). The detection rate for atypical HCCs was also significantly higher using fusion imaging (95%, 18/19) than using conventional sonography (53%, 10/19) and contrast-enhanced sonography (26%, 5/19) (p<0.01, for both).

CONCLUSION

Fusion imaging combining conventional sonography and the hepatobiliary phase of contrast-enhanced MRI with Gd-EOB-DTPA is more sensitive than conventional sonography or contrast-enhanced sonography for detecting HCCs, especially small or atypical HCCs.

Diagnostic imaging of hepatocellular carcinoma: recent progress

The diagnostic imaging of hepatocellular carcinoma (HCC) has recently undergone marked progress. The advent of the ultrasound (US) contrast agent Sonazoid, approved in January 2007, and magnetic resonance imaging (MRI) with the liver-specific MRI contrast agent gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid (Gd-EOB-DTPA-MRI), approved in January 2008, are of particular significance. Sonazoid contrast-enhanced US (Sonazoid-CEUS) is useful not only for the diagnosis of HCC, but also for guiding treatment and assessing treatment response. Sonazoid-CEUS has proven to be particularly effective for screening and staging, which used to be considered impossible with CEUS, through the introduction of the newly developed diagnostic technique of defect reperfusion imaging. It is still not possible if other vascular agents such as SonoVue and Definity are used. In particular, Gd-EOB-DTPA-MRI has been suggested to be much more reliable in the differentiation of early HCC from precancerous dysplastic nodules than any other modalities such as multidetector raw computed tomography, dynamic MRI, and superparamagnetic iron oxide-MRI. A decrease in contrast uptake in the hepatocyte phase observed on EOB-MRI is strongly suggestive of cancer, and the absence of early staining in the arterial phase suggests early HCC. The differential diagnostic capacity of Gd-EOB-DTPA-MRI is considered to far exceed that of what were previously the most useful imaging techniques, computed tomography (CT) during hepatic arteriography or CT during arterial portography, and to be comparable to that of the pathological diagnosis by pathologists specialized in liver.

Review of dynamic contrast-enhanced ultrasound guidance in ablation therapy for hepatocellular carcinoma

Local ablative techniques-percutaneous ethanol injection, microwave coagulation therapy and radiofrequency ablation (RFA)-have been developed to treat unresectable hepatocellular carcinoma (HCC). The success rate of percutaneous ablation therapy for HCC depends on correct targeting of the tumor via an imaging technique. However, probe insertion often is not completely accurate for small HCC nodules, which are poorly defined on conventional B-mode ultrasound (US) alone. Thus, multiple sessions of ablation therapy are frequently required in difficult cases. By means of two breakthroughs in US technology, harmonic imaging and the development of second-generation contrast agents, dynamic contrast-enhanced harmonic US imaging with an intravenous contrast agent can depict tumor vascularity sensitively and accurately, and is able to evaluate small hypervascular HCCs even when B-mode US cannot adequately characterize the tumors. Therefore, dynamic contrast-enhanced US can facilitate RFA electrode placement in hypervascular HCC, which is poorly depicted by B-mode US. The use of dynamic contrast-enhanced US guidance in ablation therapy for liver cancer is an efficient approach. Here, we present an overview of the current status of dynamic contrast-enhanced US-guided ablation therapy, and summarize the current indications and outcomes of reported clinical use in comparison with that of other modalities.

Radiofrequency ablation of hepatocellular carcinoma: Current status

Ablation therapy is one of the best curative treatment options for malignant liver tumors, and can be an alternative to resection. Radiofrequency ablation (RFA) of primary and secondary liver cancers can be performed safely using percutaneous, laparoscopic, or open surgical techniques, and RFA has markedly changed the treatment strategy for small hepatocellular carcinoma (HCC). Percutaneous RFA can achieve the same overall and disease-free survival as surgical resection for patients with small HCC. The use of a laparoscopic or open approach allows repeated placements of RFA electrodes at multiple sites to ablate larger tumors. RFA combined with transcatheter arterial chemoembolization will make the treatment of larger tumors a clinically viable treatment alternative. However, an accurate evaluation of treatment response is very important to secure successful RFA therapy. Since a sufficient safety margin (at least 0.5 cm) can prevent local tumor recurrences, an accurate evaluation of treatment response is very important to secure successful RFA therapy. To minimize complications of RFA, clinicians should be familiar with the imaging features of each type of complication. Appropriate management of complications is essential for successful RFA treatment.

Utility of contrast-enhanced ultrasonography with Sonazoid in radiofrequency ablation for hepatocellular carcinoma

BACKGROUND AND AIMS

Kupffer imaging in contrast-enhanced ultrasonography (CEUS) with Sonazoid, which lasts for 60 min or longer, may be useful in ultrasound-guided percutaneous tumor ablation. The utility of Sonazoid in radiofrequency ablation (RFA) of hepatocellular carcinoma (HCC) was investigated in this study.

METHODS

We analyzed a total of 716 HCC nodules that were detected on dynamic computed tomography in 316 patients. Detectability of these nodules was compared between CEUS and conventional ultrasonography. The effectiveness in the treatment was assessed by comparing the mean numbers of treatment sessions of RFA in patients treated with CEUS and that in historical controls matched for tumor and background conditions.

RESULTS

Detectability of tumor nodule was 83.5% in conventional ultrasonography and 93.2% in CEUS (P=0.04). Sixty-nine nodules in 52 patients were additionally detected with CEUS. The number of additionally detected tumor nodules was positively correlated with serum albumin level (P=0.016). The number of RFA sessions was 1.33±0.45 with CEUS as compared to 1.49±0.76 in the historical controls (P=0.0019).

CONCLUSIONS

CEUS with Sonazoid is useful for HCC detection in patients with a well-conserved liver function reservoir. The decrease in RFA session numbers indicated the utility of Sonazoid in RFA treatment of HCC.

Radiofrequency ablation of hepatocellular carcinoma: a literature review

Radiofrequency ablation (RFA) of liver cancers can be performed safely using percutaneous, laparoscopic, or open surgical techniques, and much of the impetus for the use of RFA has come from cohort series that have provided an evidence base for this technique. Here, we give an overview of the current status of radiofrequency ablation (RFA) for hepatocellular carcinoma (HCC), including its physical properties, to assess the characteristics that make this technique applicable in clinical practice. We review the technical development of probe design and summarize current indications and outcomes of reported clinical use. An accurate evaluation of treatment response is very important to secure successful RFA therapy since a sufficient safety margin (at least 0.5 cm) can prevent local tumor recurrences. We also provide a profile of side effects and information on the integration of this technique into the general management of patients with HCC. To minimize complications of RFA, physicians should be familiar with each feature of complication. Appropriate management of complications is essential for successful RFA treatment. Moreover, adjuvant therapy, such as molecular targeted therapies following curative therapy, is expected to further improve survival after RFA.

Radiofrequency ablation of hepatocellular carcinoma: Current status

Ablation therapy is one of the best curative treatment options for malignant liver tumors, and can be an alternative to resection. Radiofrequency ablation (RFA) of primary and secondary liver cancers can be performed safely using percutaneous, laparoscopic, or open surgical techniques, and RFA has markedly changed the treatment strategy for small hepatocellular carcinoma (HCC). Percutaneous RFA can achieve the same overall and disease-free survival as surgical resection for patients with small HCC. The use of a laparoscopic or open approach allows repeated placements of RFA electrodes at multiple sites to ablate larger tumors. RFA combined with transcatheter arterial chemoembolization will make the treatment of larger tumors a clinically viable treatment alternative. However, an accurate evaluation of treatment response is very important to secure successful RFA therapy. Since a sufficient safety margin (at least 0.5 cm) can prevent local tumor recurrences, an accurate evaluation of treatment response is very important to secure successful RFA therapy. To minimize complications of RFA, clinicians should be familiar with the imaging features of each type of complication. Appropriate management of complications is essential for successful RFA treatment.