Radiofrequency ablation of very-early-stage hepatocellular carcinoma inconspicuous on fusion imaging with B-mode US: value of fusion imaging with contrast-enhanced US

Using multimodal ultrasound technology to improve the success rate of liver tumor puncture for lesions with poor visibility on conventional ultrasound imaging

Background

The ability of conventional ultrasound (US)-guided liver biopsy to visualize certain liver lesions, particularly those affected by conditions like hepatitis or cirrhosis, which can obscure lesion boundaries and lead to inaccurate biopsy targeting, is limited. This study aimed to evaluate the potential of multimodal US techniques to improve the visibility of liver lesions that are indistinct under conventional US, and to enhance the success rate of percutaneous biopsies.

Methods

In total, 144 patients with liver masses and lesions that were not clearly visible on conventional US from October 2018 to January 2024 were enrolled in this retrospective analysis. The lesions of these patients exhibited poor visibility on conventional US, but the tumor location was visible on abdominal computerized tomography (CT) or magnetic resonance (MR) imaging scans. After excluding patients who did not undergo biopsy or patients with lesions that were remained not clearly visible on multimodal US examinations. Ultimately, a total of 95 patients were enrolled in this study. We analyzed the clinical and imaging data for all these patients. CT/MR-US fusion imaging was performed in 55 patients, contrast-enhanced ultrasound (CEUS) was performed in 95 patients, and high-frequency US was performed in 21 patients. The visibility of the lesions using these three techniques was evaluated, and the consistency between the biopsy pathology and the final diagnosis was analyzed.

Results

In the study, the detection rates of lesions using CT/MR-US fusion imaging, CEUS, and high-frequency US were 49.1%, 96.8%, and 76.2%, respectively. After confirming the target location of the lesions, all patients underwent percutaneous US-guided biopsy. The accuracy rate of the biopsies was 91.6%, and the positive concordance rate was 91.1%. Among the 13 patients with negative pathology findings after biopsy, 8 had false-negative results (based on follow-up laboratory tests and imaging results consistent with malignant tumor characteristics), resulting in a false-negative rate of 8.9%.

Conclusions

Multimodal US significantly improved the success of biopsies for liver lesions not clearly visible on conventional US, aiding in precise treatment planning.

Suppression of popping rates in radiofrequency ablation under perfluorobutane microbubbles for hepatocellular carcinoma

Aim of the study

Popping during radiofrequency ablation (RFA) for hepatocellular carcinoma (HCC) can cause complications such as bleeding and tumor seeding. Perfluorobutane microbubbles (Sonazoid, GE Healthcare) are employed to enhance visualization through the use of vascular and Kupffer imaging. This study aimed to assess the impact of Sonazoid on popping during RFA for HCC and evaluate popping and local recurrence rates.

Material and methods

We examined 135 patients and 308 nodules undergoing RFA for HCC using a unipolar needle electrode between December 2019 and December 2023. Popping and local recurrence rates were compared between RFA groups with and without Sonazoid.

Results

The cohort comprised 99 males and 36 females, with a mean age of 72 (range: 35-93) years. Background liver conditions included 21 hepatitis B virus (HBV), 44 hepatitis C virus (HCV), and 70 non-HBV/HCV cases. The group without Sonazoid had 267 nodes, while the Sonazoid group had 41 nodes. In energy-related comparisons, the Sonazoid group exhibited lower power (p = 0.039) and energy delivery (p = 0.013) and shorter cauterization time (p = 0.021). The popping rate during cauterization was significantly lower in the Sonazoid group (28.8% vs. 12.2%, p = 0.023). There was no significant difference in local recurrence rate between the two groups.

Conclusions

RFA with Sonazoid using a unipolar needle-type electrode reduced power output, enabling lower-energy ablation and shorter ablation times. This suggests a potential for suppressing the popping phenomenon. Low-power ablation did not affect local recurrence rates, highlighting RFA as a less invasive treatment strategy. Further studies with larger cohorts are needed to evaluate treatment efficacy.

A Comparative Study of SonoVue and Sonazoid for Contrast-Enhanced Ultrasound CT/MRI Fusion Guidance During Radiofrequency Ablation of Poorly Visualized Hepatic Malignancies: A Prospective Intra-Individual Analysis

PURPOSE

This study aimed to evaluate the effectiveness of two contrast agents, SonoVue (SV) and Sonazoid (SZ), by comparing them intra-individually in contrast-enhanced ultrasound (CEUS)-CT/MRI fusion imaging (FI) to improve the visibility of inconspicuous liver malignancies on B-mode sonography for guiding percutaneous radiofrequency ablation (RFA). Additionally, the radiologists' preference between SonoVue- CT/MRI FI (SV-FI) and Sonazoid-CT/MRI FI (SZ-FI) was determined.

METHODS

This prospective study enrolled 23 patients with inconspicuous hepatic malignancies (≤ 3 cm) on B-mode US who underwent both SV-FI and SZ-FI for RFA guidance. The patients underwent real-time CEUS FI with CT/MRI on the same day, utilizing both SV and SZ with at least 15-min intervals. Tumor visibility and radiologists' preferences were assessed and graded using a 4-point scale during the dynamic phases of both SV-FI and SZ-FI and the Kupffer phase of SZ-FI.

RESULTS

The tumor visibility scores obtained from CEUS-CT/MRI FI were significantly better than those obtained from US-FI. Indeed, SV-FI and SZ-FI demonstrated comparable visibility scores when corresponding phases were compared (p > 0.05). However, the Kupffer phase images of SZ-FI displayed superior visibility scores (3.70 ± 0.56 vs. 2.96 ± 0.88; p = 0.002) than the late vascular phase images of SV-FI. The radiologists favored SZ-FI in many cases, exhibiting moderate inter-observer agreement (Kappa value = 0.587; 95% CI, 0.403-0.772).

CONCLUSION

Although CEUS-CT/MRI FI with either SV or SZ substantially improved the visibility of inconspicuous tumors on US-CT/MRI FI, radiologists preferred SZ to SV to guide the RFA procedure.

Contrast-Enhanced Ultrasound With Perfluorobutane for Hepatocellular Carcinoma Diagnosis: Comparison of Imaging Phases and Diagnostic Criteria

BACKGROUND. Contrast-enhanced ultrasound (CEUS) with perfluorobutane has used varying protocols and diagnostic criteria for hepatocellular carcinoma (HCC). OBJECTIVE. The purpose of this article was to assess diagnostic performance for HCC of CEUS with perfluorobutane in high-risk patients using various criteria. METHODS. This retrospective post hoc study evaluating individual patient data from three earlier prospective studies from one hospital included 204 patients (136 men, 68 women; mean age, 63 ± 11 [SD] years) at high risk of HCC with 213 liver observations. Patients underwent CEUS using perfluorobutane from March 2019 to June 2022. Three radiologists (the examination's operator and two subsequent reviewers) independently interpreted examinations, assessing arterial, portal venous (arterial phase completion through 2 minutes), transitional (2-5 minutes after injection), and Kupffer (≥ 10 minutes after injection) phase findings. Six criteria for HCC were tested: 1, any arterial phase hyperenhancement (APHE) with Kupffer phase hypoenhancement; 2, nonrim APHE with Kupffer phase hypoenhancement; 3, nonrim APHE with portal venous washout; 4, nonrim APHE with portal venous washout and/or Kupffer phase hypoenhancement; 5, nonrim APHE with portal venous and/or transitional washout; 6, nonrim APHE with any of portal venous washout, transitional washout, or Kupffer phase hypoenhancement. Depending on the criteria, observations were instead deemed to be a non-HCC malignancy if showing rim APHE, early washout (at < 1 minute), or marked washout (at 2 minutes). Reference was pathology for malignant observations and pathology or imaging follow-up for benign observations. Diagnostic performance was assessed, pooling readers' data. RESULTS. Criterion 1 (no recognized features of non-HCC malignancy) had highest sensitivity (86.9%) but lowest specificity (43.2%) for HCC. Compared with nonrim APHE and portal venous washout (criterion 3), the addition of Kupffer phase hypoenhancement (criterion 4), transitional washout (criterion 5), or either feature (criterion 6) significantly increased sensitivity (34.4% vs 62.6-64.2%) and accuracy (61.8% vs 75.1-76.5%), but significantly decreased specificity (98.5% vs 91.9-94.1%). Criteria 2, 4, 5, and 6 (all incorporating transitional washout and/or Kupffer phase hypoenhancement) showed no significant differences in sensitivity (62.6-64.2%), specificity (91.9-94.1%), or accuracy (75.1-76.5%). CONCLUSION. Recognition of features of non-HCC malignancy improved specificity for HCC. Incorporation of the findings of transitional washout and/or Kupffer phase hypoenhancement improved sensitivity and accuracy, albeit lowered specificity, versus arterial and portal venous findings alone, without further performance variation among criteria incorporating those two findings. CLINICAL IMPACT. Kupffer phase acquisition may be optional for observations classified as HCC or non-HCC malignancy by arterial, portal venous, and transitional phases.

Contrast-enhanced ultrasonography-CT/MRI fusion guidance for percutaneous ablation of inconspicuous, small liver tumors: improving feasibility and therapeutic outcome

BACKGROUND

Percutaneous radiofrequency ablation (RFA) is pivotal for treating small malignant liver tumors, but tumors often remain inconspicuous on B-mode ultrasound (US). This study evaluates the potential of CEUS-CT/MRI fusion imaging (FI) to improve tumor visibility and the associated RFA outcomes for small (≤ 3 cm) malignant liver tumors that were inconspicuous on US.

METHODS

Between January 2019 and April 2021, a prospective study enrolled 248 patients with liver malignancies (≤ 3 cm) that were poorly visible on B-mode US. Tumor visibility and ablation feasibility were assessed using B-mode US, US-CT/MRI FI, and CEUS-CT/MRI FI, and graded on a 4-point scale. CEUS was employed post-registration of US and CT/MRI images, utilizing either SonoVue or Sonazoid. Comparisons between US-based and CEUS-based fusion visibility and feasibility scores were undertaken using the Friedman test. Moreover, rates of technical success, technique efficacy, local tumor progression (LTP), and major complications were assessed.

RESULTS

The cohort included 223 hepatocellular carcinomas (HCCs) (89.9%) and 23 metastases (9.3%), with an average tumor size of 1.6 cm. CEUS-CT/MRI FI demonstrated a significant advantage in tumor visibility (3.4 ± 0.7 vs. 1.9 ± 0.6, P < 0.001) and technical feasibility (3.6 ± 0.6 vs. 2.9 ± 0.8, P < 0.001) compared to US-FI. In 85.5% of patients, CEUS addition to US-FI ameliorated tumor visibility. Technical success was achieved in 99.6% of cases. No severe complications were reported. One and two-year post CEUS-CT/MRI FI-guided RFA estimates for LTP were 9.3% and 10.9%, respectively.

CONCLUSIONS

CEUS-CT/MRI FI significantly improves the visualization of tumors not discernible on B-mode US, thus augmenting percutaneous RFA success and delivering improved therapeutic outcomes.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT05445973. Registered 17 June 2022 - Retrospectively registered, http://clinicaltrials.gov/study/NCT05445973?id=NCT05445973&rank=1 .

Combined Ultrasound and Computed Tomography Guidance in Radiofrequency Ablation for Hepatocellular Carcinoma Reduces Local Recurrence Rate

Background/Aim

In radiofrequency ablation (RFA) treatment of hepatocellular carcinoma (HCC), the therapeutic effect depends on the appropriate position of the electrode. To improve the accuracy of the electrode needle position, we currently perform RFA with combined ultrasound sonography (US) and computed tomography (CT) guidance. The purpose of this study was to evaluate the effectiveness of this US/CT-guided RFA method.

Patients and Methods

This retrospective study recruited 97 patients with single tumors treated with transcatheter arterial chemoembolization and monopolar RFA between January 2013 and December 2017. Among these, 50 patients were treated with RFA under US/CT guidance (US/CT-guided group) and 47 were treated with RFA under US guidance alone (US-guided group). We analyzed the efficacy of US/CT guidance compared with US guidance alone.

Results

The 1-, 2-, and 3-year local recurrence rates for the US/CT-guided and US-guided groups were 4.1%, 6.3%, and 8.6%, and 19.6%, 31.6%, and 41.9%, respectively. The local recurrence rate was lower in the US/CT-guided group (p=0.0030). Cox proportional hazards model for multivariate analysis demonstrated that the independent risk factors associated with local recurrence were tumor size (p=0.0028) and US/CT guidance (p=0.0037).

Conclusion

US/CT-guided RFA for HCC reduced the local recurrence rate compared with US-guided RFA alone.

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.

Perfluorobutane-enhanced ultrasonography with a Kupffer phase: improved diagnostic sensitivity for hepatocellular carcinoma

OBJECTIVES

To evaluate the diagnostic accuracy of perfluorobutane contrast-enhanced ultrasonography (CEUS) for hepatocellular carcinoma (HCC) and to explore how accuracy can be improved compared to conventional diagnostic criteria in at-risk patients.

METHODS

A total of 123 hepatic nodules (≥ 1 cm) from 123 at-risk patients who underwent perfluorobutane CEUS between 2013 and 2020 at three institutions were retrospectively analyzed. Ninety-three percent of subjects had pathological results, except benign lesions stable in follow-up images. We evaluated presence of arterial phase hyperenhancement (APHE), washout time and degree, and Kupffer phase (KP) defects. KP defects are defined as hypoenhancing lesions relative to the liver in KP. HCC was diagnosed in two ways: (1) Liver Imaging Reporting and Data System (LI-RADS) criteria defined as APHE and late (≥ 60 s)/mild washout, and (2) APHE and Kupffer (AK) criteria defined as APHE and KP defect. We explored grayscale features that cause misdiagnosis of HCC and reflected in the adjustment. Diagnostic performance was compared using McNemar's test.

RESULTS

There were 77 HCCs, 15 non-HCC malignancies, and 31 benign lesions. An ill-defined margin without hypoechoic halo on grayscale applied as a finding that did not suggest HCC. Regarding diagnosis of HCC, sensitivity of AK criteria (83.1%; 95% confidence interval [CI]: 72.9-90.7%) was higher than that of LI-RADS criteria (75.3%; 95% CI: 64.2-84.4%; p = 0.041). Specificity was 91.3% (95% CI: 79.2-97.6%) in both groups.

CONCLUSION

On perfluorobutane CEUS, diagnostic criteria for HCC using KP defect with adjustment by grayscale findings had higher diagnostic performance than conventional criteria without losing specificity.

KEY POINTS

• Applying Kupffer phase defect instead of late/mild washout and adjusting with grayscale findings can improve the diagnostic performance of perfluorobutane-enhanced US for HCC. • Adjustment with ill-defined margins without a hypoechoic halo for features unlikely to be HCC decreases false positives for HCC diagnosis using the perfluorobutane-enhanced US. • After adjustment with grayscale findings, the sensitivity and accuracy of the APHE and Kupffer criteria were higher than those of the LI-RADS criteria; specificity was 91.3% for both.

Fusion imaging-guided radiofrequency ablation for residual hepatocellular carcinoma invisible on ultrasound after transcatheter arterial chemoembolization

PURPOSE

This study aimed to investigate the technical efficiency and therapeutic response of fusion imaging (considered as virtual navigation) between contrast-enhanced ultrasound (CEUS) and contrast-enhanced computed tomography/magnetic resonance imaging (CECT/CEMRI) for the guidance of radiofrequency ablation (RFA) in patients with residual hepatocellular carcinoma (HCC) after transcatheter arterial chemoembolization (TACE).

METHODS

For this prospective study, 98 patients with residual HCC lesions after TACE treatment were enrolled between June 2017 and December 2020. All the lesions were invisible on conventional ultrasound scans. Percutaneous RFA was performed using either CEUS (CEUS group, 52 lesions) or virtual navigation (VN group, 46 lesions) guidance. The lesion display rate, disease-free survival rate, local recurrence rate, overall survival rate and complication incidence were calculated and compared.

RESULTS

Fusion imaging had a significant impact on the RFA outcomes (hazard ratio, 2.629; 95% confidence interval, 1.256-5.505; p = .01). The median disease-free survival time of the VN group was significantly higher than that of the CEUS group (10.9 vs. 8.8 months; p = .007). The local recurrence rates after 3, 6 and 12 months in the VN group were significantly lower than those in the CEUS group (p = .014, .002 and .011). The minor complication rate was not significantly different between the two groups.

CONCLUSIONS

CEUS-CECT/CEMRI fusion imaging for guiding RFA enables an efficient and useful therapy of inconspicuous HCC lesions after TACE. The novel solution prolongs the disease-free survival time and reduces the long-term local recurrence of residual lesions treated when using virtual-navigation (VN)-guided RFA.

Percutaneous radiofrequency ablation for hepatic metastasis of colorectal cancer: assessment of tumor visibility and the feasibility of the procedure with planning ultrasonography

Purpose

The aim of this study was to assess the incidence and causes of percutaneous radiofrequency ablation (RFA) infeasibility in cases of metastatic colorectal cancer and to evaluate factors affecting the invisibility of the tumor on planning ultrasonography (US).

Methods

This study screened 386 patients who underwent planning US using fusion imaging and/or contrast-enhanced US for percutaneous RFA for suspected metastatic colorectal cancer between January 2013 and December 2020, from whom 136 patients with a single hepatic metastasis from colorectal cancer measuring <3 cm were included. The factors related to the infeasibility of percutaneous RFA were investigated. Univariate and multivariate analyses were performed to assess the factors associated with tumor invisibility on planning US.

Results

Among the 136 patients, percutaneous RFA was considered infeasible in 24.3% (33/136) due to a high risk of the heat-sink effect caused by the abutment of a large vessel (n=12), an inconspicuous tumor on planning US (n=11), a high risk of collateral thermal damage to an adjacent organ (n=8), and the absence of a safe electrode path (n=2). In univariate and multivariate analyses, tumor size was a statistically significant factor affecting invisibility on planning US (P=0.003 and P=0.018, respectively).

Conclusion

Percutaneous RFA was infeasible in approximately one-fourth of patients with metastatic colorectal cancer. The reason for the infeasibility was mainly an unfavorable tumor location and invisibility on planning US. Small tumor size was the sole significant factor affecting the invisibility of hepatic metastases on planning US.

Effect of Perfluorobutane Microbubbles on Radiofrequency Ablation for Hepatocellular Carcinoma: Suppression of Steam Popping and Its Clinical Implication

Objective

To evaluate the effect of perfluorobutane microbubbles (Sonazoid®, GE Healthcare) on steam popping during radiofrequency (RF) ablation for treating hepatocellular carcinoma (HCC), and to assess whether popping affects treatment outcomes.

Materials and Methods

The institutional review board approved this retrospective study, which included 90 consecutive patients with single HCC, who received percutaneous RF ablation as the first-line treatment. The patients were divided into two groups, based on the presence or absence of the popping phenomenon, which was defined as an audible sound with a simultaneous sudden explosion within the ablation zone as detected via ultrasonography during the procedure. The factors contributing to the popping phenomenon were identified using multivariable logistic regression analysis. Local tumor progression (LTP) and disease-free survival (DFS) were assessed using the Kaplan-Meier method with the log-rank test for performing comparisons between the two groups.

Results

The overall incidence of the popping phenomenon was 25.8% (24/93). Sonazoid® was used in 1 patient (4.2%) in the popping group (n = 24), while it was used in 15 patients (21.7%) in the non-popping group (n = 69). Multivariable analysis revealed that the use of Sonazoid® was the only significant factor for absence of the popping phenomenon (odds ratio = 0.10, p = 0.048). There were no significant differences in cumulative LTP and DFS between the two groups (p = 0.479 and p = 0.424, respectively).

Conclusion

The use of Sonazoid® has a suppressive effect on the popping phenomenon during RF ablation in patients with HCC. However, the presence of the popping phenomenon may not affect clinical outcomes.

Benefits of contrast-enhanced ultrasonography for interventional procedures

For evaluating unclear tumorous lesions, contrast-enhanced ultrasonography (CEUS) is an important imaging modality in addition to contrast-enhanced computed tomography and magnetic resonance imaging, and may provide valuable insights into the microvascularization of tumors in dynamic examinations. In interventional procedures, CEUS can make a valuable contribution in pre-, peri-, and post-interventional settings, reduce radiation exposure and, under certain circumstances, decrease the number of interventions needed for patients.

Bilious pleuritis due to hepatic microwave ablation: Two illustrative cases and literature review

Ultrasound guided percutaneous thermal ablation has been well acknowledged in treating hepatic malignancy. Although thermal ablation is safe for the treatment, it may induce some lethal complications such as diaphragmatic injury, bile-stained pleural fistula, and bilious pleuritis.We presented 2 cancer patients in hepatic diaphragmatic dome showed diaphragmatic injury, bile-stained pleural fistula, and bilious pleuritis after microwave ablation (MVA). The symptoms were attenuated after chest drainage and anti-infection therapy. In the literature review, 17 articles published in the recent 10 years on diaphragmatic injury after MVA for treating hepatic cancer were available. Twenty-three cases were obtained, among which 2 showed bilious pleuritis after radiofrequency treatment. Most of the lesions were adjacent to the diaphragma. Among the articles reporting the localization of lesions, most of the cases showed lesions in S8, 2 in S7, 3 in S4, and 3 in S5, respectively. Surgical recovery was required for the patients with massive diaphragmatic injury. Only 2 cases underwent thorascopic surgery. After chest drainage and anti-infection, their symptoms were attenuated to some extent.Radiofrequency or MVA may induce pleural effusion, and special attention should be paid to the diaphragmatic injury induced by thermal ablation.

Advanced Fusion Imaging and Contrast-Enhanced Imaging (CT/MRI-CEUS) in Oncology

Fusion imaging depicts an innovative technique that facilitates combining assets and reducing restrictions of advanced ultrasound and cross-sectional imaging. The purpose of the present retrospective study was to evaluate the role of fusion imaging for assessing hepatic and renal lesions. Between 02/2011-08/2020, 92 patients in total were included in the study, of which 32 patients had hepatic lesions, 60 patients had renal lesions. Fusion imaging was technically successful in all patients. No adverse side effects upon intravenous (i.v.) application of SonoVue® (Bracco, Milan, Italy) were registered. Fusion imaging could clarify all 11 (100%) initially as indeterminate described hepatic lesions by computed tomography/magnetic resonance imaging (CT/MRI). Moreover, 5/14 (36%) initially suspicious hepatic lesions could be validated by fusion imaging, whereas in 8/14 (57%), malignant morphology was disproved. Moreover, fusion imaging allowed for the clarification of 29/30 (97%) renal lesions initially characterized as suspicious by CT/MRI, of which 19/30 (63%) underwent renal surgery, histopathology revealed malignancy in 16/19 (84%), and benignity in 3/19 (16%). Indeterminate findings could be elucidated by fusion imaging in 20/20 (100%) renal lesions. Its accessibility and repeatability, even during pregnancy and in childhood, its cost-effectiveness, and its excellent safety profile, make fusion imaging a promising instrument for the thorough evaluation of hepatic and renal lesions in the future.

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.

Perfluorobutane contrast-enhanced ultrasonography: a new standard for ultrasonography-guided thermal ablation of sonographically occult liver tumours?

INTRODUCTION

Image-guided thermal ablation, preferably with ultrasonography (US), is increasingly used for treatment of small liver tumours. Perfluorobutane-contrast enhanced US (pCEUS) is a promising tool that may allow for targeting of tumours that are otherwise imperceptible on greyscale US. Although pCEUS has been reported to be effective, the literature has been limited outside of Japan and South Korea. We aimed to provide data that supports the use of pCEUS in thermal ablation of sonographically occult liver tumours.

METHODS

We conducted a retrospective single-centre study of 35 consecutive patients who underwent pCEUS-guided ablation of 48 liver tumours with a median size of 1.2 cm. Periprocedural, one-month post-treatment, and relevant follow-up imaging studies were reviewed. Electronic records were also obtained, with long-term follow-up data of 12-28 months being available for 32 patients.

RESULTS

36 (75%) of tumours that were imperceptible on greyscale US became visible with pCEUS. Overall, complete tumour ablation at one month was 89%. 1 (3%) patient developed a major complication following treatment, while 6 (17%) had minor post-treatment complaints. The local tumour progression rate was 17% with a median time of 14 months.

CONCLUSION

pCEUS has a role in US-guided thermal ablation of liver tumours, offering a high technical success rate that is comparable to reported data. Additional benefits may include improved procedural time and freedom from ionising radiation.

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.

Ultrasound fusion imaging technologies for guidance in ablation therapy for liver cancer

With advances in imaging technology, images from ultrasound (US) and computed tomography (CT) or magnetic resonance imaging (MRI) can be displayed simultaneously and in real time, according to the angle of the transducer. CT/MR-US fusion imaging improves the visualization of inconspicuous hepatocellular carcinoma (HCC) and helps us to understand the three-dimensional relationship between the liver vasculature and HCC. US fusion imaging guidance facilitates improvement in the treatment response for HCC with poor conspicuity, and the rates of technical success of ablation and local tumor progression for inconspicuous HCC range from 94.4 to 100% and 0 to 8.3%, respectively. Moreover, the development of image fusion has made it possible to compare and overlay pre- and post-ablation US images. This US-US fusion imaging allows side-by-side comparison of the ablative margin, while US-US overlay fusion can visualize the ablative margin because the tumor image is projected onto the ablative hyperechoic zone. Thus, US-US overlay fusion guidance is highly effective for safety margin achievement in local ablation therapy for HCC, providing a lower risk of local tumor progression. This manuscript reviews the current status of ultrasound fusion imaging for percutaneous ablation therapy of HCC.

RF Ablation Versus Cryoablation for Small Perivascular Hepatocellular Carcinoma: Propensity Score Analyses of Mid-Term Outcomes

PURPOSE

This study aimed to compare radiofrequency (RF) ablation with cryoablation in patients with perivascular hepatocellular carcinoma (HCC) and evaluate the mid-term outcomes of both therapies.

MATERIALS AND METHODS

Between January 2015 and April 2018, 111 patients who underwent percutaneous cryoablation (n = 61) or RF ablation (n = 50) for a single perivascular HCC were included. Perivascular HCC was defined as the presence of contacting peritumoral hepatic vessels that were 3 mm or larger in axial diameter. Local tumor progression (LTP) rates were compared by propensity score matching. Procedure-related complications were also assessed.

RESULTS

The median follow-up was 23 months (range 2-45 months). Twenty-five patients were matched in each group. The cumulative LTP rates at 1 and 3 years were 8.3% and 17.3% in the cryoablation group and 8.7% and 26.1% in the RF ablation group, with no significant difference (p = 0.379). Although there were no significant differences between the two groups, vascular thrombosis (16.0% vs. 9.8%, p = 0.493) and hepatic infarction (12.0% vs. 3.3%, p = 0.137) more frequently occurred in the RF ablation group than in the cryoablation group.

CONCLUSION

In patients with perivascular HCC, cryoablation is an effective alternative treatment compared with RF ablation regarding local tumor control and complications.

LEVEL OF EVIDENCE

Level 4 (retrospective case-control study).

Percutaneous image-guided ablation: From techniques to treatments

Image-guided ablation is performed by percutaneously introducing ablation probes to deliver energy into a tumor to destroy it in a controlled and localized fashion. Ablation modalities can be broadly classified as thermal or non-thermal based on the mechanism of tumor destruction and are performed using different types of image guidance for planning, delivering and follow-up of the treatment. Ablation is performed in a minimally invasive fashion, providing greater residual organ preservation with minimal morbidity to the patient. Image-guided ablation is being used in the clinic for the treatment of primary and metastatic tumors, and this article reviews state of the art for the treatment of malignancies in the liver, lung, kidney and musculoskeletal tissue.

[Contrast-enhanced ultrasound (CEUS) and image fusion for procedures of liver interventions]

CLINICAL/METHODICAL ISSUE

Contrast-enhanced ultrasound (CEUS) is becoming increasingly important for the detection and characterization of malignant liver lesions and allows percutaneous treatment when surgery is not possible. Contrast-enhanced ultrasound image fusion with computed tomography (CT) and magnetic resonance imaging (MRI) opens up further options for the targeted investigation of a modified tumor treatment.

METHODICAL INNOVATIONS

Ultrasound image fusion offers the potential for real-time imaging and can be combined with other cross-sectional imaging techniques as well as CEUS.

PERFORMANCE

With the implementation of ultrasound contrast agents and image fusion, ultrasound has been improved in the detection and characterization of liver lesions in comparison to other cross-sectional imaging techniques. In addition, this method can also be used for intervention procedures. The success rate of fusion-guided biopsies or CEUS-guided tumor ablation lies between 80 and 100% in the literature.

ACHIEVEMENTS

Ultrasound-guided image fusion using CT or MRI data, in combination with CEUS, can facilitate diagnosis and therapy follow-up after liver interventions.

PRACTICAL RECOMMENDATIONS

In addition to the primary applications of image fusion in the diagnosis and treatment of liver lesions, further useful indications can be integrated into daily work. These include, for example, intraoperative and vascular applications as well applications in other organ systems.

Thermal ablation with fusion imaging guidance of hepatocellular carcinoma without conspicuity on conventional or contrast-enhanced US: surrounding anatomical landmarks matter

AIM

Evaluating clinical and technical factors affecting thermal ablation of B-Mode/CEUS inconspicuous HCC nodules, relying only on fusion imaging (FI) performed under conscious sedation and using previously acquired CT or MR.

MATERIALS AND METHODS

Among 367 HCC nodules treated in the study period, data of 37 B-mode/CEUS undetectable HCC nodules treated with FI-guided ablation were extracted from our prospectively collected institutional database. Analyzed variables included patients' sex, age, cirrhosis etiology, Child-Pugh status, size of the lesion, liver segment, subcapsular or central liver site, type of imaging used for fusion (MR/CT), and the presence of surrounding anatomical landmarks (SAL) < 3 cm from the index lesion.

RESULTS

The primary efficacy was 59.4% (22/37 nodules); nine lesions (24.3%) were partially ablated (PA), six lesions (16.7%) were mistargeted (MA). Eight nodules were retreated with a CA obtained in all cases (100% CA, secondary efficacy in 30/37-81.1%). LTP was observed in 2/30 cases (6.7%). Two minor complications were registered (Clavien-Dindo, Grade1, CIRSE Classification Grade 2). SAL were related to a better ablation outcome (37.5% vs 84.6% p = 0.01). No differences were observed between CA group and PA-MA group in terms of lesion size (15.4 mm vs 14.9 mm p = 0.63), liver segment (p = 0.58), subcapsular or central liver site (8/22 36% vs 4/15 26.7% p = 0.84), and imaging (MR vs CT, p = 0.72).

CONCLUSION

Even in the presence of potentially critical conditions (completely B-Mode/CEUS inconspicuous nodules, spontaneous breathing, and previously acquired CT or MRI), FI-only guidance is safe and allows having good primary, secondary efficacy and LTP rates. The outcome of the procedure is heavily affected by the presence of SAL.

Usefulness of real-time contrast-enhanced ultrasound guided coaxial needle biopsy for focal liver lesions

PURPOSE

To evaluate the utility of real-time contrast-enhanced ultrasound (CEUS)-guided coaxial needle biopsies for focal liver lesions (FLL) that were inconspicuous or could not be accurately identified the active site on B-mode ultrasound (US).

MATERIALS AND METHODS

This prospective study included 76 patients who had CEUS-guided coaxial needle biopsies for FLL between December 2015 and June 2017. We recorded characteristics of target lesions. We evaluated conspicuity of target lesions and accuracy of identifying the active site of target lesions on B-mode US and CEUS using a 5-point scale. Patients were divided into three groups, and analyzed according to body mass index (BMI). Based on the final diagnosis, the diagnostic performance was evaluated.

RESULTS

The mean size and depth of target lesions were 41.5 ± 28.5 and 47.9 ± 18.9 mm on CEUS, respectively. In arterial phase, the enhanced pattern of target lesions varied. The conspicuity of target lesions and accuracy of identifying the active site of target lesions was significantly improved on CEUS compared to B-mode US (p < 0.05). The three BMI groups had significant differences in conspicuity of target lesions after using CEUS (p < 0.05). The high BMI group had a greater change in conspicuity of lesions compared to the normal BMI group or the low BMI group (p < 0.05). The sensitivity, specificity, and accuracy of this technique for the diagnosis of FLL were 92.8%, 100%, and 93.4%, respectively.

CONCLUSION

Real-time CEUS-guided coaxial needle biopsy can be very useful for FLL that are inconspicuous or cannot be accurately identified the active site on B-mode US.

Additional value of contrast-enhanced ultrasonography for fusion-guided, percutaneous biopsies of focal liver lesions: prospective feasibility study

PURPOSE

To determine the value of CEUS for real-time, fusion-guided, percutaneous biopsies of focal liver lesions.

MATERIALS AND METHODS

Institutional review board approval and written informed consents were obtained for this study. Forty patients with focal liver lesions identified on CT/MRI were prospectively enrolled. For biopsy planning, real-time fusion of CT/MRI with USG (USG-Fusion) was performed, and subsequently real-time CEUS was fused with CT/MRI (CEUS-Fusion). We evaluated lesion visibility, confidence level of technical success before the procedure, and safety route accessibility on USG-Fusion and CEUS-Fusion. Occurrence of change in the biopsy target was also assessed.

RESULTS

Among 40 target lesions, nine (22.5%) lesions were invisible on USG-Fusion. After applying CEUS-Fusion, seven of nine (77.8%) lesions were visualized. Confidence level of technical success of procedure was significantly increased on CEUS-Fusion compared USG-Fusion (p = 0.02), and presumed target lesions were changed in 16 (40%) patients after CEUS-Fusion. As the lesion is necrotic, presumed target was more frequently changed after CEUS-Fusion (50.0% and 25.0%). Confirmative diagnostic results were reported in 39 (97.5%) patients. Accessibility of the safety route to target lesions did not reach statistical differences.

CONCLUSION

Applying a new, real-time CEUS-Fusion with CT/MRI improved tumor visibility and viable portion assessment, thus leading to higher operator confidence and diagnostic yield, when compared with conventional USG-Fusion.

Radiofrequency ablation for subcardiac hepatocellular carcinoma: therapeutic outcomes and risk factors for technical failure

OBJECTIVES

To compare the therapeutic outcomes and safety of radiofrequency (RF) ablation for subcardiac and non-subcardiac hepatocellular carcinoma (HCC) and to evaluate the risk factors for technical failure of the procedure.

METHODS

This retrospective study was approved by the institutional review board. Between September 2002 and May 2016, 73 patients with subcardiac HCC and the same number of patients with non-subcardiac HCC matched by tumor size were included. Subcardiac HCC was defined as an index tumor that was located ≤ 1 cm from the pericardium in axial or coronal images. Cumulative local tumor progression (LTP) was compared between the two groups using the log-rank test. Prognostic factors for technical failure were assessed using multivariable logistic analysis.

RESULTS

Technical success rates between both groups were not significantly different (91.8% in the subcardiac HCC group vs. 95.9% in the non-subcardiac HCC group; p = 0.494). The cumulative LTP rates were 15.4% and 19.1% at 3 and 5 years, respectively, in the subcardiac HCC group, and 10.7% and 15.5% in the non-subcardiac HCC group, without significant difference (p = 0.862). The distance between the index tumor and pericardium (odds ratio [OR], 0.14; p = 0.023) and tumor in segment IV (reference, left lateral sector; OR, 36.53; p = 0.029) were significant factors for technical failure in patients with subcardiac HCC.

CONCLUSIONS

RF ablation was an effective treatment for subcardiac HCC. However, tumor location should be considered in the planning of treatment to avoid technical failure.

KEY POINTS

• RF ablation for subcardiac HCC is technically feasible without major complications. • RF ablation was an effective treatment for subcardiac HCC in terms of LTP. • Risk factors for technical failure were distance of the index tumor from the heart (cutoff value of 0.5 cm) and the location of the tumor (segment IV).

The usefulness of contrast-enhanced harmonic EUS-guided fine-needle aspiration for evaluation of hepatic lesions (with video)

BACKGROUND AND AIMS

Small hepatic masses often do not have distinct margins on B-mode EUS images. Contrast-enhanced harmonic EUS (CEH-EUS) is widely used for evaluating ambiguous pancreatic lesions. However, its role in detecting hepatic lesions and the use of EUS-guided FNA are not well evaluated. We investigated the usefulness of CEH-EUS-guided FNA for evaluating hepatic lesions.

METHODS

Thirty consecutive patients with hepatic masses underwent CEH-EUS and CEH-EUS-guided FNA between September 2010 and November 2016.

RESULTS

Twenty-eight patients (93.3%) had malignant tumors and 2 patients (6.7%) had benign hepatic masses. Before contrast enhancement, 73.3% of the hepatic lesions (22/30) in the patient cohort were visible on B mode. After contrast enhancement, 93.3% of these hepatic lesions (28/30) were distinguishable from the surrounding liver parenchyma. The technical success rate was 100%. The median tumor size on EUS and the number of needle passes were 24.5 mm (interquartile range [IQR], 14.5-40.8) and 2 (IQR, 2-3), respectively. The diagnostic accuracy of CEH-EUS-guided FNA was 86.7% (26/30 cases). There were no procedure-related adverse events.

CONCLUSIONS

CEH-EUS-guided FNA can be a safe and efficient method for the diagnosis of hepatic masses. It can result in high diagnostic accuracy in cases where the hepatic lesions are poorly visible on conventional EUS.

Percutaneous cryoablation for perivascular hepatocellular carcinoma: Therapeutic efficacy and vascular complications

OBJECTIVES

To evaluate the therapeutic efficacy of and vascular complications associated with percutaneous cryoablation for the treatment of perivascular HCC.

METHODS

Between August 2015 and September 2017, 58 consecutive patients (48 men, 10 women; mean age, 61.1 years; age range, 44-84 years) who underwent percutaneous cryoablation were included. All patients had a single perivascular HCC (mean size, 1.3 cm; Barcelona clinic liver cancer-stage 0 or A) that was in contact with hepatic vessels, ≥ 3 mm or larger in axial diameter. Local tumour progression (LTP) was estimated by the Kaplan-Meier method. In addition, several procedure-related vascular complications were evaluated immediately after treatment and during follow-up CT: peritumoral vessel thrombosis; infarction; aggressive intrasegmental recurrence (AIR) (the simultaneous development of ≥ 3 nodular or infiltrative tumours). The follow-up CT was performed in all patients 1 month after the procedure, and every 3 months thereafter.

RESULTS

The median follow-up period was 22 months (range, 3-29 months). The technical success rate of cryoablation was 96.6% (56/58). The 1- and 2-year cumulative LTP rates were 3.6% and 14.6%, respectively. Although peritumoral vessel thrombosis occurred in 6.9% of cases (4/58), no cases of hepatic infarction were observed and AIR did not develop during follow-up. Half of the thombi in the peritumoral vessels immediately after cryoablation disappeared on follow-up CT images.

CONCLUSION

Cryoablation could be an effective tool for the treatment of perivascular HCC with a very low risk of vascular complications.

KEY POINTS

• Cryoablation allowed a high technical success rate for perivascular HCC. • Only 6.9% developed peritumoral vessel thrombosis without major vascular complications like infarction. • Two-year cumulative LTP rate was 14.6%, without aggressive tumour recurrence on follow-up.

Percutaneous US/MRI Fusion-guided Radiofrequency Ablation for Recurrent Subcentimeter Hepatocellular Carcinoma: Technical Feasibility and Therapeutic Outcomes

Purpose To evaluate the technical feasibility and therapeutic outcomes of percutaneous US/MRI fusion-guided radiofrequency ablation (RFA) of recurrent subcentimeter-sized hepatocellular carcinomas (HCCs). Materials and Methods For this retrospective study, between January 2012 and December 2014 a total of 194 planning US examinations were performed in 186 patients (159 men and 27 women; mean age, 61.1 years ± 10.0 [standard deviation]) for newly developed subcentimeter recurrent HCCs. These recurrent HCCs were defined as hypervascular nodules (>5.5 mm and <10 mm) with typical MRI findings of HCC. The study assessed how often US/MRI fusion-guided percutaneous RFA was deemed technically feasible at planning US examination (the feasibility rate) and the therapeutic outcomes after RFA, including the rates of technical success, technique efficacy, local tumor progression (LTP), and major complications. Cumulative LTP rates were estimated with the Kaplan-Meier method. Results The feasibility rate of percutaneous RFA at planning US examination was 65.7% (138 of 210 HCCs). The most common reason for RFA infeasibility was that an index tumor was inconspicuous at US. Among 138 subcentimeter HCCs feasible for RFA, 125 lesions underwent percutaneous RFA. The rates of both technical success and technique efficacy were 98.4% (123 of 125). The cumulative LTP rates at 1, 2, and 3 years were 3.6%, 5.4%, and 7.4%, respectively. The major complication rate was 2.5% (three of 119). Conclusion Percutaneous US/MRI fusion-guided radiofrequency ablation (RFA) was feasible in approximately two-thirds of subcentimeter recurrent hepatocellular carcinomas (HCCs). Percutaneous US/MRI fusion-guided RFA is a safe and effective treatment modality for patients with subcentimeter recurrent HCCs.

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.

Focal Nodular Hyperplasia of the Liver: Contrast-Enhanced Ultrasonographic Features With Sonazoid

OBJECTIVES

To investigate ultrasonographic features of focal nodular hyperplasia of the liver with contrast-enhanced ultrasonography (CEUS) using Sonazoid (perflubutane; GE Healthcare, Oslo, Norway).

METHODS

Thirty-one patients with 31 focal nodular hyperplasia nodules who underwent CEUS using Sonazoid between July 2012 and February 2015 were included in this study. After the microbubble contrast agent was injected, intermittent CEUS images were obtained during the following 4 phases: arterial (10-40 seconds), portal venous (60-90 seconds), delayed (3 minutes), and Kupffer (>10 minutes). Three abdominal radiologists retrospectively reviewed the images and achieved consensus for vascular (central artery, stellate vascularity, and centrifugal enhancement) and dynamic enhancement patterns during the late arterial, portal venous, delayed, and Kupffer phases.

RESULTS

The patients included 12 men and 19 women (age range, 21-82 years; mean, 47 years). The mean diameter of the lesions ± SD was 2.2 ± 0.9 cm (range, 1.0-4.0 cm). On CEUS, 24 of 31 lesions (77.4%) showed central artery and stellate vascularity in the early arterial phase, and 25 (80.6%) showed centrifugal enhancement. Twenty-six lesions (83.9%) were hyperechoic during the late arterial phase and showed hyperenhancement or isoenhancement during the serial dynamic phases. Kupffer-phase images indicated that only 2 lesions (6.5%) were hypoechoic compared with surrounding liver parenchyma, whereas 29 (93.5%) remained either hyperechoic (2 [6.5%]) or isoechoic (27 [87.1%]).

CONCLUSIONS

Contrast-enhanced US using Sonazoid for focal nodular hyperplasia showed typical vascular patterns of central artery vascularity, stellate vascularity, and centrifugal enhancement. Most cases were either hyperenhanced or isoenhanced on serial dynamic- and Kupffer-phase imaging. Based on these results, CEUS can provide useful information for noninvasive focal nodular hyperplasia diagnoses.

Fusion imaging with contrast-enhanced ultrasonography for evaluating the early therapeutic efficacy of radiofrequency ablation for small hypervascular hepatocellular carcinomas with iso-echoic or unclear margins on conventional ultrasonography

PURPOSE

We evaluated the efficacy of fusion imaging combining contrast-enhanced ultrasonography (CEUS) images and arterial phase contrast-enhanced CT (CECT) or hepatobiliary phase magnetic resonance imaging with gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (EOB-MRI) images for the early evaluation of the effectiveness of radiofrequency ablation (RFA) for small hypervascular hepatocellular carcinoma (HCC) with iso-echoic or unclear margins on conventional US.

METHODS

Forty HCCs (22 iso-echoic and 18 unclear margin lesions) with mean diameters of 13.7 mm were treated using RFA under the guidance of fusion imaging with CEUS. The adequacy of RFA was evaluated using fusion imaging with CEUS 1 day after RFA. CECT or EOB-MRI was performed 1 month after RFA. We reviewed the images obtained using both modalities.

RESULTS

When the 1-month CECT or EOB-MRI scans were used as the reference standard, the sensitivity, specificity, and accuracy of the 1-day fusion imaging for the diagnosis of the adequate ablation of these HCCs were 97, 100, and 98%, respectively; the kappa value for the agreement between the findings using the two modalities was 0.655.

CONCLUSION

Fusion imaging with CEUS appears to be a useful method for the early evaluation of the efficacy of RFA for the treatment of HCCs with iso-echoic or unclear margins on conventional US.

Ultrasound-Guided Radiofrequency Ablation Using a New Electrode with an Electromagnetic Position Sensor for Hepatic Tumors Difficult to Place an Electrode: A Preliminary Clinical Study

PURPOSE

To evaluate whether a new electrode embedded with an electromagnetic position sensor (EMPS) improves the technical feasibility of percutaneous radiofrequency ablation (RFA) in patients with hepatic tumors difficult to place an electrode under ultrasonography (US) guidance and to assess short-term therapeutic efficacy and safety.

MATERIALS AND METHODS

This prospective study was approved by the institutional review board, and written informed consent was obtained from all patients. Between January 2015 and December 2016, 10 patients (7 men and 3 women; age range 52-75 years) with a single hepatic tumor (median 1.4 cm; range 1.1-1.8 cm) difficult to place an electrode under US guidance were enrolled. The technical feasibility of targeting and overlapping ablation during the RFA procedure was graded using a four-point scale and analyzed using the Wilcoxon signed rank test according to the use of EMPS. In addition, the rates of technical success, local tumor progression (LTP), and major complications were assessed.

RESULTS

The use of the new RF electrode with EMPS significantly improved the technical feasibility of targeting and overlapping ablation (p = 0.002 and p = 0.003, respectively). After treatment, the technical success rate was 100%. LTP was not found in any patient during the follow-up period (median 8 months; range 4-22 months). No major procedure-related complications occurred.

CONCLUSIONS

The technical feasibility of percutaneous RFA improves with the use of this RF electrode embedded with an EMPS. Short-term therapeutic efficacy and safety after RFA using the electrode were promising in patients with hepatic tumors difficult to place an electrode under US guidance.

Percutaneous Dual-Switching Monopolar Radiofrequency Ablation Using a Separable Clustered Electrode: A Preliminary Study

Objective

To prospectively evaluate the safety and therapeutic effectiveness of dual-switching monopolar (DSM) radiofrequency ablation (RFA) for the treatment of hepatocellular carcinoma (HCC), and to retrospectively compare the results with those of single-switching monopolar (SSM) RFA in a historical control group.

Materials and Methods

This study was approved by the Institutional Review Board, with informed consent obtained from all patients. Fifty-two HCC patients who underwent DSM-RFA using a separable clustered electrode and dual-generators were prospectively enrolled. Technical parameters, complications, technical success, technical effectiveness, and local tumor progression (LTP) rates were evaluated by means of post-procedural and follow-up imaging. Thereafter, the outcome of DSM-RFA was compared with those of 249 retrospectively included HCC patients treated with SSM-RFA.

Results

There were two major complications (3.8%, 2/52) including pleural and pericardial effusion in the DSM-RFA group. The DSM-RFA yielded a 100% technical success rate, a 98.1% technical effectiveness rate, and a 4.3% 2-year LTP rate. In a retrospective comparison between the two groups, DSM-RFA created significantly larger ablation volume (4.20 ± 2.07 cm³/min vs. 3.03 ± 1.99 cm³/min, p < 0.01), and delivered higher energy (1.43 ± 0.37 kcal/min vs. 1.25 ± 0.50 kcal/min, p < 0.01) per given time, than SSM-RFA. There was no significant difference in major procedure-related complications (3.8% vs. 4.4%) and technical effectiveness rate (98.1% vs. 96.4%) between the two groups (p = 1.00). In addition, the 2-year LTP rate of DSM-RFA and SSM-RFA were 4.3% and 10.1%, respectively (p = 0.15).

Conclusion

DSM-RFA using a separable clustered electrode is safe and provides high local tumor control and good preliminary clinical outcome for small HCCs, which are at least comparable to those of SSM-RFA.

Transarterial chemoembolization for early stage hepatocellular carcinoma decrease local tumor control and overall survival compared to radiofrequency ablation

BACKGROUND & AIMS

To compare treatment failure and survival associated with ultrasound-guided radiofrequency ablation (RFA) and trans-arterial chemoembolization (TACE) for early-stage HCC in Child-Pugh A cirrhosis patients.

METHODS

122 cirrhotic patients (RFA: 61; TACE: 61) were well matched according to cirrhosis severity; tumor size and serum alpha-fetoprotein. TACE was performed in case of inconspicuous nodule on US or nodule with "at risk location". Treatment failure was defined as local tumor progression (LTP) and primary treatment failure (failing to obtain complete response after two treatment session). Treatment failure and overall survival (OS) were compared after coarsened exact matching. Cox proportional model to assess independent predictive factors was performed.

RESULTS

No significant difference was seen for baseline characteristics between the two groups. Mean tumor size was 3cm in both group with 41% HCC>3cm. Treatment failure rates after TACE was 42.6% (14 primary treatment failures and 12 LTP) and 9.8% after RFA (no primary treatment failure and 6 LTP) P < 0.001. TACE was the only predictive factor of treatment failure (Hazard ratio: 5.573). The 4-years OS after RFA and TACE were 54.1% and 31.5% (P = 0.042), respectively.

CONCLUSION

For Child-Pugh A patients with early-stage HCC, alternative treatment as supra-selective TACE to RFA regarded as too challenging using common US guidance decrease significantly the local tumor control and overall survival. Efforts to improve feasibility of RFA especially for inconspicuous target have to be made.

Cone Beam CT-Guided Chemoembolization of Probable Hepatocellular Carcinomas Smaller than 1 cm in Patients at High Risk of Hepatocellular Carcinoma

PURPOSE

To evaluate the effectiveness and safety of cone-beam computed tomography (CT)-guided chemoembolization for probable hepatocellular carcinomas (HCCs) smaller than 1 cm in patients at high risk for HCC.

MATERIALS AND METHODS

From December 2009 to May 2014, 57 patients (43 male and 14 female; mean age, 61.1 y) at high risk for HCC underwent cone-beam CT-guided conventional chemoembolization for 79 treatment-naive probable HCCs < 1 cm. Probable HCCs were diagnosed when hepatic nodules showed arterial enhancement and washout on dynamic CT or magnetic resonance images. The Kaplan-Meier method and Cox proportional-hazards regression were used to evaluate the time to local progression (TTLP), time to progression (TTP), and overall survival (OS).

RESULTS

Initial follow-up images obtained 2-3 months after chemoembolization showed complete response in all 79 tumors. The 1-, 2-, and 3-year local progression rates were 10.4%, 21.7%, and 35.7%, respectively. Subsegmental catheterization (P < .001; hazard ratio [HR] = .041) and segmental catheterization (P = .001; HR = .049) were significantly associated with longer TTLP. The 1-, 2-, and 3-year progression rates were 40.5%, 66.7%, and 78.6%, respectively. Tumor multiplicity (P = .004; HR = 2.612) was a significant risk factor for shorter TTP. The 1-, 2-, and 3-year OS rates were 100%, 98.2%, and 88.5%, respectively. Child-Turcotte-Pugh class B disease (P = .029; HR = 5.989) was significantly associated with shorter OS. No complications occurred after chemoembolization.

CONCLUSIONS

Cone-beam CT-guided chemoembolization can be a useful and safe option for probable HCCs < 1 cm in patients at high risk for HCC.

Phantom Study Investigating the Accuracy of Manual and Automatic Image Fusion with the GE Logiq E9: Implications for use in Percutaneous Liver Interventions

Purpose

To determine the accuracy of automatic and manual co-registration methods for image fusion of three-dimensional computed tomography (CT) with real-time ultrasonography (US) for image-guided liver interventions.

Materials and Methods

CT images of a skills phantom with liver lesions were acquired and co-registered to US using GE Logiq E9 navigation software. Manual co-registration was compared to automatic and semiautomatic co-registration using an active tracker. Also, manual point registration was compared to plane registration with and without an additional translation point. Finally, comparison was made between manual and automatic selection of reference points. In each experiment, accuracy of the co-registration method was determined by measurement of the residual displacement in phantom lesions by two independent observers.

Results

Mean displacements for a superficial and deep liver lesion were comparable after manual and semiautomatic co-registration: 2.4 and 2.0 mm versus 2.0 and 2.5 mm, respectively. Both methods were significantly better than automatic co-registration: 5.9 and 5.2 mm residual displacement (p < 0.001; p < 0.01). The accuracy of manual point registration was higher than that of plane registration, the latter being heavily dependent on accurate matching of axial CT and US images by the operator. Automatic reference point selection resulted in significantly lower registration accuracy compared to manual point selection despite lower root-mean-square deviation (RMSD) values.

Conclusion

The accuracy of manual and semiautomatic co-registration is better than that of automatic co-registration. For manual co-registration using a plane, choosing the correct plane orientation is an essential first step in the registration process. Automatic reference point selection based on RMSD values is error-prone.

Added Value of Contrast-Enhanced Ultrasound on Biopsies of Focal Hepatic Lesions Invisible on Fusion Imaging Guidance

Objective

To assess whether contrast-enhanced ultrasonography (CEUS) with Sonazoid can improve the lesion conspicuity and feasibility of percutaneous biopsies for focal hepatic lesions invisible on fusion imaging of real-time ultrasonography (US) with computed tomography/magnetic resonance images, and evaluate its impact on clinical decision making.

Materials and Methods

The Institutional Review Board approved this retrospective study. Between June 2013 and January 2015, 711 US-guided percutaneous biopsies were performed for focal hepatic lesions. Biopsies were performed using CEUS for guidance if lesions were invisible on fusion imaging. We retrospectively evaluated the number of target lesions initially invisible on fusion imaging that became visible after applying CEUS, using a 4-point scale. Technical success rates of biopsies were evaluated based on histopathological results. In addition, the occurrence of changes in clinical decision making was assessed.

Results

Among 711 patients, 16 patients (2.3%) were included in the study. The median size of target lesions was 1.1 cm (range, 0.5–1.9 cm) in pre-procedural imaging. After CEUS, 15 of 16 (93.8%) focal hepatic lesions were visualized. The conspicuity score was significantly increased after adding CEUS, as compared to that on fusion imaging (p < 0.001). The technical success rate of biopsy was 87.6% (14/16). After biopsy, there were changes in clinical decision making for 11 of 16 patients (68.8%).

Conclusion

The addition of CEUS could improve the conspicuity of focal hepatic lesions invisible on fusion imaging. This dual guidance using CEUS and fusion imaging may affect patient management via changes in clinical decision-making.

Fusion imaging of contrast-enhanced ultrasound and contrast-enhanced CT or MRI before radiofrequency ablation for liver cancers

OBJECTIVE

To investigate the usefulness of fusion imaging of contrast-enhanced ultrasound (CEUS) and CECT/CEMRI before percutaneous ultrasound-guided radiofrequency ablation (RFA) for liver cancers.

METHODS

45 consecutive patients with 70 liver lesions were included between March 2013 and October 2015, and all the lesions were identified on CEMRI/CECT prior to inclusion in the study. Planning ultrasound for percutaneous RFA was performed using conventional ultrasound, ultrasound-CECT/CEMRI and CEUS and CECT/CEMRI fusion imaging during the same session. The numbers of the conspicuous lesions on ultrasound and fusion imaging were recorded. RFA was performed according to the results of fusion imaging. Complete response (CR) rate was calculated and the complications were recorded.

RESULTS

On conventional ultrasound, 25 (35.7%) of the 70 lesions were conspicuous, whereas 45 (64.3%) were inconspicuous. Ultrasound-CECT/CEMRI fusion imaging detected additional 24 lesions thus increased the number of the conspicuous lesions to 49 (70.0%) (70.0% vs 35.7%; p < 0.001 in comparison with conventional ultrasound). With the use of CEUS and CECT/CEMRI fusion imaging, the number of the conspicuous lesions further increased to 67 (95.7%, 67/70) (95.7% vs 70.0%, 95.7% vs 35.7%; both p < 0.001 in comparison with ultrasound and ultrasound-CECT/CEMRI fusion imaging, respectively). With the assistance of CEUS and CECT/CEMRI fusion imaging, the confidence level of the operator for performing RFA improved significantly with regard to visualization of the target lesions (p = 0.001). The CR rate for RFA was 97.0% (64/66) in accordance to the CECT/CEMRI results 1 month later. No procedure-related deaths and major complications occurred during and after RFA.

CONCLUSION

Fusion of CEUS and CECT/CEMRI improves the visualization of those inconspicuous lesions on conventional ultrasound. It also facilitates improvement in the RFA operators' confidence and CR of RFA. Advances in knowledge: CEUS and CECT/CEMRI fusion imaging is better than both conventional ultrasound and ultrasound-CECT/CEMRI fusion imaging for lesion visualization and improves the operator confidence, thus it should be recommended to be used as a routine in ultrasound-guided percutaneous RFA procedures for liver cancer.

[Possibilities of sonographic image fusion: Current developments]

CLINICAL/METHODICAL ISSUE

For diagnostic and interventional procedures ultrasound (US) image fusion can be used as a complementary imaging technique.

METHODICAL INNOVATIONS

Image fusion has the advantage of real time imaging and can be combined with other cross-sectional imaging techniques.

PERFORMANCE

With the introduction of US contrast agents sonography and image fusion have gained more importance in the detection and characterization of liver lesions.

ACHIEVEMENTS

Fusion of US images with computed tomography (CT) or magnetic resonance imaging (MRI) facilitates the diagnostics and postinterventional therapy control.

PRACTICAL RECOMMENDATIONS

In addition to the primary application of image fusion in the diagnosis and treatment of liver lesions, there are more useful indications for contrast-enhanced US (CEUS) in routine clinical diagnostic procedures, such as intraoperative US (IOUS), vascular imaging and diagnostics of other organs, such as the kidneys and prostate gland.

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.

Recent Advances in Tumor Ablation for Hepatocellular Carcinoma

Image-guided tumor ablation for early stage hepatocellular carcinoma (HCC) is an accepted non-surgical treatment that provides excellent local tumor control and favorable survival benefit. This review summarizes the recent advances in tumor ablation for HCC. Diagnostic imaging and molecular biology of HCC has recently undergone marked improvements. Second-generation ultrasonography (US) contrast agents, new computed tomography (CT) techniques, and liver-specific contrast agents for magnetic resonance imaging (MRI) have enabled the early detection of smaller and inconspicuous HCC lesions. Various imaging-guidance tools that incorporate imaging-fusion between real-time US and CT/MRI, that are now common for percutaneous tumor ablation, have increased operator confidence in the accurate targeting of technically difficult tumors. In addition to radiofrequency ablation (RFA), various therapeutic modalities including microwave ablation, irreversible electroporation, and high-intensity focused ultrasound ablation have attracted attention as alternative energy sources for effective locoregional treatment of HCC. In addition, combined treatment with RFA and chemoembolization or molecular agents may be able to overcome the limitation of advanced or large tumors. Finally, understanding of the biological mechanisms and advances in therapy associated with tumor ablation will be important for successful tumor control. All these advances in tumor ablation for HCC will result in significant improvement in the prognosis of HCC patients. In this review, we primarily focus on recent advances in molecular tumor biology, diagnosis, imaging-guidance tools, and therapeutic modalities, and refer to the current status and future perspectives for tumor ablation for HCC.

Contrast-enhanced ultrasound for the evaluation of acute renal infarction

A 65-year-old male in the dilated phase of hypertrophic cardiomyopathy and with persistent atrial fibrillation was admitted to our hospital because of an episode of ventricular fibrillation following an appropriate shock from an implantable cardiac defibrillator (ICD). At admission, electrocardiography showed a normal sinus rhythm. He had complained of back pain 7 days after the ICD shock. Renal infarction was suspected, although computed tomography and magnetic resonance imaging could not be performed because of chronic renal failure and the presence of his ICD. We, therefore, used contrast-enhanced ultrasonography with a contrast agent to evaluate his acute kidney injury. This showed the left kidney contained a wedge-shaped area that was not enhanced by the contrast agent, indicating an area of infarction.

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.

Ablation of hepatocellular carcinoma

Radiofrequency ablation (RFA) has gained a wide acceptance as a first-line therapeutic option for small hepatocellular carcinoma (HCC). For very early-stage HCC, despite a higher rate of local tumour progression, RFA is considered as a viable alternative to surgical resection owing to its comparable long-term survival, reduced morbidity, and greater preservation of hepatic parenchyma. For HCCs larger than 2 cm, RFA can contribute to near-curative therapy when combined with chemoembolization. RFA can be used as part of a multimodal treatment strategy for more advanced or recurrent cases, and could be a useful bridging therapy for patients who are waiting for liver transplantation. However, the use of RFA is still limited in treating large tumours and some tumours in high-risk locations. To overcome its current limitations, other ablation techniques are being developed and it is important to validate the role of other techniques for enhancing performance of ablation therapy for HCC.

Contrast-enhanced ultrasonography: advance and current status in abdominal imaging

In the field of contrast-enhanced ultrasonography (US), contrast agents are classified as either first- or second-generation agents depending on the gas within the microbubbles. In the case of first-generation contrast agents, a high-mechanical-index technique is used and only intermittent scanning is possible due to the early destruction of the microbubbles during the scanning. The use of second-generation contrast agents in a low-mechanical-index technique enables continuous scanning. Besides the detection and characterization of focal liver lesions, contrastenhanced US is helpful in the monitoring of radiofrequency ablation therapy and in the targeting step of an US-guided biopsy. Recently, there has been a demand for new criteria to evaluate the treatment response obtained using anti-angiogenic agents because morphologic criteria alone may not reflect the treatment response of the tumor and contrast-enhanced US can provide quantitative markers of tissue perfusion. In spite of the concerns related to its cost-effectiveness, contrast-enhanced US has the potential to be more widely used as a complimentary tool or to substitute the current imaging modalities in some occasions.

Fusion imaging of real-time ultrasonography with CT or MRI for hepatic intervention

With the technical development of ultrasonography (US), electromagnetic tracking-based fusion imaging of real-time US and computed tomography/magnetic resonance (CT/MR) images has been used for percutaneous hepatic intervention such as biopsy and radiofrequency ablation (RFA). Because of the fusion imaging technique, the fused CT or MR images show the same plane and move synchronously while performing real-time US. With this information, fusion imaging can enhance lesion detectability and reduce the false positive detection of focal hepatic lesions with poor sonographic conspicuity. Three-dimensional US can also be fused with realtime US for the percutaneous RFA of liver tumors requiring overlapping ablation. When fusion imaging is not sufficient for identifying small focal hepatic lesions, contrast-enhanced US can be added to fusion imaging.