Usefulness of contrast-enhanced ultrasonography with abdominal virtual ultrasonography in assessing therapeutic response in hepatocellular carcinoma treated with radiofrequency ablation

3D fusion is superior to 2D point-to-point contrast-enhanced US to evaluate the ablative margin after RFA for hepatocellular carcinoma

PURPOSE

To compare the efficiency of three-dimensional (3D) and two-dimensional (2D) contrast-enhanced ultrasound (CEUS)-derived techniques in evaluating the ablative margin (AM) after radiofrequency ablation (RFA) for hepatocellular carcinoma (HCC).

METHODS

In total, 98 patients with 98 HCCs were enrolled. The 2D CEUS point-to-point imaging (2D CEUS-PI) was conducted by comparing the pre- and post-RFA 2D CEUS images manually, and the 3D CEUS fusion imaging (3D CEUS-FI) was conducted by fusing the pre- and post-RFA 3D CEUS images automatically. These two techniques were compared in distinguishing an adequate AM ≥ 5 mm. Risk factors for local tumor progression (LTP) after RFA were analyzed by the Kaplan-Meier method with log-rank test.

RESULTS

The mean registration time of 3D CEUS-FI and 2D CEUS-PI was 5.0 and 9.3 min, respectively (p < 0.0001). The kappa coefficient was 0.680 for agreement between 2D CEUS-PI and 3D CEUS-FI in the evaluation of AM (p < 0.0001). Tumors with AM < 5 mm by 2D CEUS-PI were all identified as AM < 5 mm by 3D CEUS-FI. Nonetheless, 16 (26%) tumors identified as AM ≥ 5 mm by 2D CEUS-PI were re-classified as AM < 5 mm by 3D CEUS-FI. During a median follow-up time of 31.2 months (range, 3.2-66.0 months), LTP was identified in 8 tumors. The estimated 1-/2-/3-year cumulative incidence of LTP was 4.4%, 8.1%, and 10.3%, respectively. Higher estimated cumulative incidence of LTP was identified in tumors with AM < 5 mm by 2D CEUS-PI (at 3-year, 27.2% vs 0%; p < 0.001), and by 3D CEUS-FI (at 3-year, 20.7% vs 0%; p = 0.004).

CONCLUSION

3D CEUS-FI excelled in the evaluation of AM when compared with 2D CEUS-PI. With equivalent efficacy in the prediction of LTP, 3D CEUS-FI was superior to 2D CEUS-PI for its automatic and time-saving procedure.

CLINICAL RELEVANCE STATEMENT

3D CEUS fusion imaging may serve as an effective tool in evaluating ablative margin and predicting local tumor progression after RFA in HCC.

KEY POINTS

• Both 2D and 3D CEUS-derived techniques could evaluate ablative margin (AM) after RFA for hepatocellular carcinoma. • 3D CEUS fusion imaging was more precise in the evaluation of AM compared to 2D CEUS point-to-point imaging, with advantages of its automatic and time-saving procedure. • An inadequate AM < 5 mm evaluated by CEUS-derived techniques was the only risk factor of LTP after RFA for hepatocellular carcinoma (p < 0.001 for 2D CEUS point-to-point imaging, and p = 0.004 for 3D CEUS fusion imaging).

Achievement of Complete Response and Drug-Free Status by Atezolizumab plus Bevacizumab Combined with or without Curative Conversion in Patients with Transarterial Chemoembolization-Unsuitable, Intermediate-Stage Hepatocellular Carcinoma: A Multicenter Proof-Of-Concept Study

Introduction

Atezolizumab plus bevacizumab therapy is extremely effective in the treatment of intermediate-stage hepatocellular carcinoma (HCC), with a response rate of 44%, as reported in the IMbrave150 trial. When tumor shrinkage is obtained, achieving complete response (CR) is possible in many cases using curative conversion with resection, ablation, or superselective transarterial chemoembolization (TACE) with curative intent. This concept, i.e., curative conversion by combining systemic therapy and locoregional therapy, has not been reported before. This multicenter proof-of-concept study was conducted to show the value of curative conversion in immunotherapy-treated intermediate-stage HCC meeting TACE-unsuitable criteria.

Methods

This study included 110 consecutive Child-Pugh A patients who received atezolizumab plus bevacizumab as first-line treatment for unresectable and TACE-unsuitable intermediate-stage HCC at seven centers in Japan. CR rate, drug-free rate, time to CR, change in liver function, efficacy in positron emission tomography (PET)-positive HCC, progression-free survival (PFS), and overall survival (OS) were assessed in patients who achieved CR using resection, ablation, superselective TACE with curative intent following atezolizumab plus bevacizumab or atezolizumab plus bevacizumab alone.

Results

Clinical or pathological CR was achieved in 38 patients (35%) (median observation period: 21.2 months). The modalities of curative conversion in 35 patients were as follows: resection, 7; ablation, 13; and superselective TACE, 15. Three patients achieved clinical CR with atezolizumab plus bevacizumab therapy alone. Among the 38 CR patients, 25 achieved drug-free status. PFS was not reached, and 3 patients experienced recurrence after reaching CR. Regarding OS, there were no deaths in any of the CR patients. The albumin-bilirubin score did not deteriorate after locoregional therapy or resection. Of seven PET-positive patients who achieved CR with atezolizumab plus bevacizumab followed by curative conversion, five achieved drug-free status.

Conclusion

The achievement of CR rate by curative conversion in patients treated with atezolizumab plus bevacizumab as the preceding therapy for unresectable and TACE-unsuitable intermediate-stage HCC was 35%. Overall, 23% of patients achieved drug-free status and no recurrence was observed from this patient subgroup with CR and drug-free status. Thus, achieving CR and/or drug-free status should be a therapeutic goal for patients with intermediate-stage HCC without vascular invasion or extrahepatic spread.

A Review of Imaging Methods to Assess Ultrasound-Mediated Ablation

Ultrasound ablation techniques are minimally invasive alternatives to surgical resection and have rapidly increased in use. The response of tissue to HIFU ablation differs based on the relative contributions of thermal and mechanical effects, which can be varied to achieve optimal ablation parameters for a given tissue type and location. In tumor ablation, similar to surgical resection, it is desirable to include a safety margin of ablated tissue around the entirety of the tumor. A factor in optimizing ablative techniques is minimizing the recurrence rate, which can be due to incomplete ablation of the target tissue. Further, combining focal ablation with immunotherapy is likely to be key for effective treatment of metastatic cancer, and therefore characterizing the impact of ablation on the tumor microenvironment will be important. Thus, visualization and quantification of the extent of ablation is an integral component of ablative procedures. The aim of this review article is to describe the radiological findings after ultrasound ablation across multiple imaging modalities. This review presents readers with a general overview of the current and emerging imaging methods to assess the efficacy of ultrasound ablative treatments.

Meta-analysis and systematic review of contrast-enhanced ultrasound in evaluating the treatment response after locoregional therapy of hepatocellular carcinoma

PURPOSE

Contrast-enhanced ultrasound (CEUS) is a useful tool to assess treatment response after percutaneous ablation or transarterial chemoembolization (TACE) of hepatocellular carcinoma (HCC). Here, we performed a systematic review and meta-analysis to evaluate the usefulness of CEUS in identifying residual tumor after locoregional therapy.

METHODS

PubMed, Scopus, and Cochrane library databases were searched from their inception until March 8, 2021, for diagnostic test accuracy studies comparing CEUS to a reference standard for identifying residual tumors after locoregional therapy of HCC. The pooled sensitivity, specificity, accuracy, and diagnostic odds ratio (DOR) were obtained using a bivariate random effects model. Subgroup analyses were performed by stratifying the studies based on study design, type of locoregional therapy, CEUS criteria for residual tumor, timing of CEUS follow up, and type of standard reference.

RESULTS

Two reviewers independently evaluated 1479 publications. After full-text review, 142 studies were found to be relevant, and 43 publications (50 cohorts) were finally included. The overall sensitivity of CEUS in detection of residual disease estimated from the bivariate random effects model was 0.85 (95% CI 0.80-0.89). Similarly, the overall specificity was 0.94 (95% CI 0.91-0.96). The diagnostic accuracy was 93.5%. The DOR was 70.1 (95% CI 62.2-148), and the AUROC was 0.95. Importantly, subgroup analysis showed no apparent differences in the diagnostic performance between locoregional therapy (TACE vs. ablation) and criteria used to define residual enhancement, timing of performing CEUS, study design, or type of reference standard.

CONCLUSION

CEUS is a highly accurate method to identify HCC residual tumor after TACE or percutaneous ablation.

Guidelines and Good Clinical Practice Recommendations for Contrast Enhanced Ultrasound (CEUS) in the Liver - Update 2020 - WFUMB in Cooperation with EFSUMB, AFSUMB, AIUM, and FLAUS

The present, updated document describes the fourth iteration of recommendations for the hepatic use of contrast enhanced ultrasound (CEUS), first initiated in 2004 by the European Federation of Societies for Ultrasound in Medicine and Biology (EFSUMB). The previous updated editions of the guidelines reflected changes in the available contrast agents and updated the guidelines not only for hepatic but also for non-hepatic applications.The 2012 guideline requires updating as previously the differences of the contrast agents were not precisely described and the differences in contrast phases as well as handling were not clearly indicated. In addition, more evidence has been published for all contrast agents. The update also reflects the most recent developments in contrast agents, including the United States Food and Drug Administration (FDA) approval as well as the extensive Asian experience, to produce a truly international perspective.These guidelines and recommendations provide general advice on the use of ultrasound contrast agents (UCA) and are intended to create standard protocols for the use and administration of UCA in liver applications on an international basis to improve the management of patients.

Guidelines and Good Clinical Practice Recommendations for Contrast-Enhanced Ultrasound (CEUS) in the Liver-Update 2020 WFUMB in Cooperation with EFSUMB, AFSUMB, AIUM, and FLAUS

The present, updated document describes the fourth iteration of recommendations for the hepatic use of contrast-enhanced ultrasound, first initiated in 2004 by the European Federation of Societies for Ultrasound in Medicine and Biology. The previous updated editions of the guidelines reflected changes in the available contrast agents and updated the guidelines not only for hepatic but also for non-hepatic applications. The 2012 guideline requires updating as, previously, the differences in the contrast agents were not precisely described and the differences in contrast phases as well as handling were not clearly indicated. In addition, more evidence has been published for all contrast agents. The update also reflects the most recent developments in contrast agents, including U.S. Food and Drug Administration approval and the extensive Asian experience, to produce a truly international perspective. These guidelines and recommendations provide general advice on the use of ultrasound contrast agents (UCAs) and are intended to create standard protocols for the use and administration of UCAs in liver applications on an international basis to improve the management of patients.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Contrast-enhanced ultrasonography used for post-treatment responses evaluation of radiofrequency ablations for hepatocellular carcinoma: a meta-analysis

OBJECTIVE

This meta-analysis aims to analyze the usefulness of contrast-enhanced ultrasonography (CEUS) for post-treatment responses evaluation of radiofrequency ablation (RFA) for hepatocellular carcinoma (HCC) management.

METHODS

Literature retrieval in three databases PubMed, Embase and Cochrane Library was conducted up to September 2015, with pre-defined criteria. The technical success rate, local tumour recurrence and local tumour progression were the measurement indexes. Cochran's Q test and I(2) were used for heterogeneity detection. Subgroup analyses were performed for complete ablation rate stratified by study designs, contrast agents and post-operative testing time points. Statistical analyses were conducted using Stata(®) 12.0 software (Stata Corporation, College Station, TX).

RESULTS

12 studies consisting of 772 patients were included in this study. The CEUS-evaluated success rate of RFA for HCCs was 91%. The proportion of ablative margin <5 mm was 53%. The local tumour recurrence rate and local tumour progression rate were 4% and 8%, respectively. Subgroup analysis indicated that the CEUS-assessed technical success rate with Sonazoid™ (Daiichi-Sankyo, Tokyo, Japan) as the contrast agent was higher (95%) than those with other agents [SH U 508A (Schering AG, Berlin, Germany) 86%; SonoVue (Bracco SpA, Milan, Italy) 87%]. The success rate assessed within 24 h (94%) after treatment was higher than longer time (1-3 days 86%; 1 month 91%).

CONCLUSION

The meta-analysis showed that the CEUS-evaluated success rate of RFA for HCCs was 91%. The local tumour recurrence rate and local tumour progression rate were 4% and 8%, respectively.

ADVANCES IN KNOWLEDGE

Using meta-analysis, the study provided more reliable assessment of usefulness of CEUS, which could provide guidelines for HCC treatment.

Imaging Diagnosis of Hepatocellular Carcinoma: Recent Advances of Contrast-Enhanced Ultrasonography with SonoVue®

Due to the ability to detect the typical contrast-imaging pattern for hepatocellular carcinoma (HCC), that is hyperenhancement in the arterial phase and hypoenhancement in the late phase on a cirrhotic background, contrast-enhanced ultrasonography (CEUS) was included in the American diagnostic algorithm for HCC in 2005. However, its role has been questioned because of the possibility of misdiagnosis of cholangiocarcinoma. The present review aims to describe the advantages and disadvantages of CEUS applications using Sonovue® for HCC. In particular there is focus on the accuracy of CEUS in detecting the typical HCC pattern, the CEUS patterns of intrahepatic cholangiocarcinoma (ICC), the risk of misdiagnosis with HCC, the diagnostic use of CEUS in cases of locoregional and systemic treatments, and the evaluation of response to antiangiogenic treatment using dedicated software.

Natural history of postvascular-phase iso-enhanced lesions on the sonogram in chronic liver diseases

BACKGROUND AND AIM

This study examined the natural history of postvascular-phase iso-enhanced lesions (PIELs) on contrast-enhanced sonograms to determine the potential risk and predictive factors for developing hepatocellular carcinoma (HCC) in chronic liver diseases.

METHODS

This prospective study included 87 PIELs on contrast-enhanced sonograms (postvascular-phase: 10 min post-injection of perflubutane microbubbles) in 72 patients with chronic liver diseases (45 males and 27 females; age 65.0 ± 10.8y; PIEL diameter 12.5 ± 4.2 mm). The PIELs were followed up by ultrasound/contrast-enhanced ultrasound, computed tomography, or magnetic resonance imaging at 3 to 6 months intervals.

RESULTS

Twenty patients developed HCCs during the study period (median, 22.0 months). The cumulative risk of HCC occurrence was 7.9% at 1 year and 36.0% at 3 years. The presence of coexistent HCC (hazard ratio [HR], 4.975; 95% confidence interval [CI], 1.729-14.316; P = 0.003) and alpha-fetoprotein > 20 ng/mL (HR, 4.104; 95% CI, 1.621-10.392; P = 0.003) were significant factors for the risk of HCC occurrence. Fourteen of these lesions were diagnosed as HCCs that developed from iso-enhanced lesions. Cumulative HCC occurrence rates from PIEL > 14 mm was 23.5% at 1 year and 46.3% at 3 years. Cox regression analysis showed that PIEL > 14 mm (HR, 6.780; 95% CI, 2.060-22.32; P = 0.002) and alpha-fetoprotein > 20 ng/mL (HR, 4.892; 95% CI, 1.559-15.350; P = 0.007) were statistically significant factors for HCC occurrence.

CONCLUSIONS

Patients with coexistent HCC, alpha-fetoprotein > 20 ng/mL, or PIEL > 14 mm should be carefully monitored because of the high potential for HCC occurrence.

Percutaneous transhepatic biliary drainage assisted by real-time virtual sonography: a retrospective study

Background

Real-time virtual sonography (RVS) is a diagnostic imaging support system that can synchronize with ultrasound images in conjunction with computed tomography or magnetic resonance images using magnetic navigation system. RVS has been applied in clinical practice to perform such procedures as radiofrequency ablation and biopsy; however, the application of RVS for percutaneous transhepatic biliary drainage (PTBD) is rare.

Methods

Between 2007 and 2012, RVS-assisted PTBD was performed for 30 patients (19 males and 11 females; age range, 41 to 89 years; mean age, 66.9 years) with obstructive jaundice. The targeted bile duct was determined using the RVS system before the procedure. The intervention was considered to be successful when the targeted bile duct was punctured and the drainage catheter was placed in the bile duct. Complications were evaluated according to the Society of Interventional Radiology Clinical Practice Guidelines.

Results

A total of 37 interventions were performed for 30 patients. The interventions were successful in 35 (95%) of 37 interventions. The targeted bile ducts were: B3 (n = 24), B5 (n = 7), B8 (n = 3), B6 (n = 1), and the anterior (n = 1) and posterior (n = 1) branches of the right bile duct. The mean targeted bile duct diameter was 4.9 mm (1.9 to 8.2 mm). PTBD was able to be accomplished in all patients because the non-targeted bile ducts were successfully punctured alternatively. No major complications were observed in relation to the interventional procedure.

Conclusions

RVS-assisted PTBD is a feasible and safe procedure. Accurate puncture of targeted bile ducts can be achieved using this method.

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.

Ultrasound-guided percutaneous laser and ethanol ablation of rabbit VX2 liver tumors

BACKGROUND

Only a small percentage of patients with hepatocellular carcinoma (HCC) may benefit out of surgical resection. Thus, lots of these patients are in need of local control, such as percutaneous ethanol injection (PEI), percutaneous laser ablation (PLA), or radiofrequency thermal ablation (RF).

PURPOSE

To investigate the effects of ultrasound-guided PLA combined with PEI on rabbit VX2 liver tumors, using conventional gray-scale ultrasonography (US), color/power Doppler (CD/PD)US, contrast-enhanced (CE) US, and histologic examination.

MATERIAL AND METHODS

VX2 tumors were implanted in the livers of 80 rabbits. Fourteen days after implantation, animals were randomly separated into four groups of 20 rabbits. Treatment of the four groups was with: (i) PLA; (ii) PEI; (iii) combined therapy of PLA immediately followed by PEI; and (iv) combined therapy of PEI immediately followed by PLA. Conventional gray-scale US, CD US, PD US, and CE US were performed before and after ablation. The effects on ablated areas were assessed by histologic examination.

RESULTS

Conventional gray-scale US showed a clear boundary around the ablated area in groups 1, 3, and 4. An isoechoic treated region with an irregular boundary was seen in group 2. On CE US, coagulated areas demonstrated a perfusion defect. Both conventional gray-scale US and CE US showed that the ablated volume in group 4 was larger than that in groups 1, 2, and 3. CD US and PD US demonstrated residual tumor in the periphery of ablated areas in groups 1 and 2, but not in groups 3 and 4. CE US demonstrated no residual tumor in group 4, unlike in groups 1, 2, and 3. Examination of treated tumors demonstrated necrosis in the ablated zones and increasing surrounding fibrous bands in the four treatment groups. Residual viable tissue in group 4 was less than that in groups 1, 2, and 3.

CONCLUSION

Combined therapy of PEI immediately followed by PLA can coagulate significantly larger volumes of tumor and reduce residual tumor.

Guidelines and good clinical practice recommendations for Contrast Enhanced Ultrasound (CEUS) in the liver - update 2012: A WFUMB-EFSUMB initiative in cooperation with representatives of AFSUMB, AIUM, ASUM, FLAUS and ICUS

Initially, a set of guidelines for the use of ultrasound contrast agents was published in 2004 dealing only with liver applications. A 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 non-liver applications. Time has moved on, and the need for international guidelines on the use of CEUS in the liver has become apparent. The present document describes the third iteration of recommendations for the hepatic use of contrast enhanced ultrasound (CEUS) using contrast specific imaging techniques. This joint WFUMB-EFSUMB initiative has implicated experts from major leading ultrasound societies worldwide. These liver CEUS guidelines are simultaneously published in the official journals of both organizing federations (i.e., Ultrasound in Medicine and Biology for WFUMB and Ultraschall in der Medizin/European Journal of Ultrasound for EFSUMB). These guidelines and recommendations provide general advice on the use of all currently clinically available ultrasound contrast agents (UCA). They are intended to create standard protocols for the use and administration of UCA in liver applications on an international basis and improve the management of patients worldwide.

Use of fusion imaging combining contrast-enhanced ultrasonography with a perflubutane-based contrast agent and contrast-enhanced computed tomography for the evaluation of percutaneous radiofrequency ablation of hypervascular hepatocellular carcinoma

OBJECTIVE

We evaluated the efficacy of fusion imaging, which fuses contrast-enhanced ultrasonography images with arterial-phase, contrast-enhanced CT images as a reference on a single screen in real time, for the evaluation of the effectiveness of radiofrequency ablation for treatment of hypervascular hepatocellular carcinoma.

MATERIALS AND METHODS

Eighty hepatocellular carcinoma lesions with a maximum diameter of between 1 and 3 cm that were scheduled for treatment with radiofrequency ablation were enrolled in this prospective study. After bolus injection of perflubutane-based contrast agent, fusion imaging combining contrast-enhanced ultrasonography images and arterial-phase, contrast-enhanced CT images was performed one day after radiofrequency ablation. We used two functions, which were subsets of the fusion imaging, to confirm the location of the hepatocellular carcinoma lesions in the ablated areas and to evaluate the presence or absence of an adequate safety margin. Contrast-enhanced CT was performed one month after the ablation. Two blinded observers reviewed the images obtained using both modalities to evaluate the effect of ablation.

RESULTS

When the one-month contrast-enhanced CT images were used as the reference standard, the sensitivity, specificity, and accuracy of the one-day fusion imaging for the diagnosis of adequate ablation were 97%, 83%, and 96%, respectively; the kappa value for the agreement between the findings obtained using the two modalities was 0.75.

CONCLUSION

Fusion imaging combining contrast-enhanced ultrasonography images and arterial-phase, contrast-enhanced CT images as a reference appears to be a useful method for the early evaluation of the efficacy of radiofrequency ablation for the treatment of hypervascular hepatocellular carcinoma.

Contrast-Enhanced Ultrasound (CEUS) for Echographic Detection of Hepato Cellular Carcinoma in Cirrhotic Patients Previously Treated with Multiple Techniques: Comparison of Conventional US, Spiral CT and 3-Dimensional CEUS with Navigator Technique (3DNav CEUS)

A commercially available technique named “NAVIGATOR” (Esaote, Italy) easily enables a 3-D reconstruction of a single 2-D acquisition of Contrast Enhanced Ultrasound (CEUS) imaging of the whole liver (with a volumetric correction thanks to the electromagnetic device of NAVIGATOR). Aim of the study was to evaluate this “panoramic” technique in comparison with conventional US and spiral CT in the detection of new hepatic lesions. 144 cirrhotic patients (previously treated for hepato cellular carcinoma (HCC)) in follow-up with detection of 98 new nodules (N), 28 multinodular (Nmulti), 14 loco-regional regrowth (LR) 94 efficaciously treated without new nodules (neg) and four multinodular without new nodules, were submitted to 200 examinations with this new technique from November 2008 to November 2009. 3DNavCEUS was performed using SonoVue (Bracco), as contrast agent, and a machine (Technos MPX, Esaote). Spiral CT and 3DNav CEUS were performed in the same month during follow up. Sens.,Spec.,diagn.-Acc.,PPV and NPV were evaluated; comparison and differences between the techniques were obtained with chi-square (SPSS release-15). Final diagnosis was: 98 new lesions (N) (one to three), 28 multinodular HCC (Nmulti) and 14 loco-regional regrowth (LR); in 94 no more lesions were observed during follow-up; conventional US obtained: 58 N (+18 multinodularN and 8 LR), 40 false negative (+10 Nmulti and 6 LR) (sens:59.2, spec:100%, Diagn Accur:73.6, PPV:100; NPV:70.1); spiral CT obtained: 84N (+26-multinodularN and 14-LR), 14 false-negative (+2-Nmulti), and one false-positive (sens:85.7, spec:97.9%, Diagn Accur:90.9, PPV:97.7; NPV:86.8); 3DNAV obtained: 92N (+28 multinodularN and 14LR), 6 false-negative, and two false-positives (sens:93.9, spec:97.9%, Diagn Accur:95.6, PPV:97.9; NPV:93.9). 3-DNav CEUS is significantly better than US and almost similar to spiral CT for detection of new HCC. This technique, in particular, showed the presence of lesions even in the cases not detected with spiral CT.

[Radiological diagnosis of hepatocellular carcinoma in 2010]

The aim of diagnosis imaging is to detect hepatocellular carcinoma at an early stage, when a curative treatment is available. Biopsy is no longer required prior to treatment, and diagnosis of hepatocellular carcinoma is heavily dependent of imaging characteristics. Therefore, the purpose of this article is to describe the typical features of small (<20mm) and larger hepatocellular carcinomas with noninvasive diagnostic criteria, including ultrasound, computed tomography and MRI. Advances in these imaging modalities have greatly improved the detection of small hepatic nodules on liver cirrhosis, including the different steps of carcinogenesis, from regenerative to dysplastic nodules, and we emphasize the difficulties of radiological differentiation of precancerous lesions and small hepatocellular carcinomas.

Percutaneous biopsy of anterior mediastinal mass guided by real-time US fused with CT

We report a case of successful fused CT-sonographic imaging-guided percutaneous biopsy of an anterior mediastinal mass, which was visualized poorly with conventional sonography. Real-time sonography fused with CT can be useful for biopsy of anterior mediastinal masses that are not well visualized on conventional sonography.

Microbubble-enhanced US in body imaging: what role?

Contrast agents for ultrasonography (US) comprise microscopic bubbles of gas in an encapsulating shell. They are unique in that they interact with the imaging process, oscillating in response to a low-intensity ultrasound field and disrupting in response to a high-intensity field. New contrast-specific imaging modes allow US to show exquisite vascularity and tissue perfusion in real time and with excellent spatial resolution. In Europe, Asia, and Canada, to name only the most obvious, characterization of focal liver masses is the first and best established use of contrast-enhanced (CE) US, allowing for the noninvasive diagnosis of commonly encountered liver masses with comparable accuracy to that of computed tomography and magnetic resonance studies. CE US is a preferred modality for the difficult task of diagnosis of liver nodules detected on surveillance scans in those at risk for hepatocellular carcinoma. Newer body applications include the guidance of ablative intervention, monitoring activity of bowel inflammation in Crohn disease, characterization of kidney masses, especially cystic renal cell carcinoma, diagnosis of prostate cancer, and monitoring the response of tumors to antivascular drug therapies. Microbubble contrast agents are easy to use and robust; their use poses no risk of nephrotoxicity and requires no ionizing radiation. CE US plays a vital and expanding role that improves management and patient care.

Pseudoenhancement within the local ablation zone of hepatic tumors due to a nonlinear artifact on contrast-enhanced ultrasound

OBJECTIVE

Pseudoenhancement of an avascular region on contrast-enhanced ultrasound often occurs within an echogenic region of a radiofrequency ablation zone due to nonlinear ultrasound propagation through intervening microbubble-perfused tissue. The purpose of this study was to describe the imaging features of this artifact.

MATERIALS AND METHODS

Twenty-six patients with no tumor recurrence within ablation zones were included. Two radiologists assessed contrast-enhanced ultrasound pseudoenhancement in the arterial (< 30 seconds), portal (30-90 seconds), and late (> 90 seconds) phases. If pseudoenhancement was present, the following information was recorded: the degree, time to first appearance, progression over time, and location. The corresponding gray-scale echogenicity (hypo-, iso-, or hyperechoic) and lesion depth were also noted.

RESULTS

Fourteen lesions (14/26, 54%) showed pseudoenhancement on contrast-enhanced ultrasound. Fourteen (100%) corresponded to the hyperechoic area within the ablation zone on gray-scale ultrasound and were nonmarginal in location. Pseudoenhancement occurred more frequently in deep lesions (> or = 5 cm) than in superficial lesions (< 5 cm) (p = 0.002). Pseudoenhancement was initiated most frequently in the portal phase (9/14, 64%), followed by the arterial phase (4/14, 29%) and late phase (1/14, 7%). Progression in the degree of pseudoenhancement was shown in most cases (12/14, 86%) and no washout was seen.

CONCLUSION

Pseudoenhancement is frequently seen within ablation zones on contrast-enhanced ultrasound, particularly in deep echogenic lesions. However, pseudoenhancement follows enhancement of the parenchyma between the transducer and target. This observation is consistent with nonlinear propagation of the ultrasound beam, which increases with bubble concentration. Pseudoenhancement shows relatively late initiation, progression over time, and nonmarginal location; these findings are different from those seen in typical tumor recurrence, which shows early enhancement and washout at the margin of the ablation zone.

Contrast-enhanced sonography with abdominal virtual sonography in monitoring radiofrequency ablation of hepatocellular carcinoma

BACKGROUND

Contrast-enhanced CT is regarded as the gold standard for monitoring radiofrequency ablation (RFA) of hepatocellular carcinoma (HCC). Recently, 3-dimensional volume data from CT have been used to create cross-sectional multiplanar reconstruction images. Using this technique, we can reconstruct 2-dimensional CT images identical in orientation to ultrasound (US) images, which we call virtual sonographic (VUS) images. The present prospective randomized control trial compared the number of CT scans needed to assess the efficacy of RFA of HCC using VUS-contrast-enhanced ultrasonography (CEUS) versus CT.

METHOD

Subjects comprised 50 patients (50 HCCs) treated with US-guided RFA between May 2005 and August 2006, randomized to undergo assessment by CT (Group 1; 25 HCC nodules) or VUS-CEUS (Group 2; 25 HCC nodules). All patients were followed for 1 year. Primary endpoint was whether the number of CT scans could be reduced using VUS-CEUS.

RESULT

Mean number of CT scans required was 1.64 +/- 0.7 in Group 1 and 1.1 +/- 0.2 in Group 2 (p < 0.001).

CONCLUSION

VUS-CEUS can be used to assess the efficacy of HCC of RFA, with the potential to reduce the number of CT scans required for that purpose.

Usefulness of the hyperechoic rim for assessing the therapeutic efficacy of radiofrequency ablation in hepatocellular carcinoma patients

AIM

During radiofrequency ablation (RFA) for hepatocellular carcinoma (HCC), a hyperechoic rim develops around the HCC nodules. The usefulness of the hyperechoic rim to guide treatment was assessed.

METHODS

RFA was first performed in pig livers to determine the significance of the hyperechoic rim. Fifty-five patients with 75 HCC nodules had received RFA for the treatment of HCC. For those patients, we evaluated whether conventional ultrasonography (US) could be used instead of contrast-enhanced computed tomography (CECT) and contrast-enhanced ultrasonography (CEUS) using virtual imaging. Finally, 31 patients with 45 HCC nodules received RFA, and the degree of ablation was assessed based on the hyperechoic rim. Repeated RFA was done when ablation appeared incomplete.

RESULTS

In the pig livers, the hyperechoic rim was found to be related to the presence of dead cells. The preliminary study showed that US could be used instead of CECT and CEUS to evaluate the degree of ablation caused by RFA. Because hepatic vessels in the back side of the hyperechoic rim were not clear by the artifact, we used the distance from the surface of the liver to the hyperechoic rim for evaluation. By analyzing the extent of the hyperechoic rim, it was noted that incomplete ablation was achieved in 17 of 31 patients (21 of 45 HCC nodules). These patients were re-treated with RFA within 5-15 min of the first RFA.

CONCLUSION

This study shows that the hyperechoic rim is related to the presence of dead and necrotic tissues. Thus, assessment of the hyperechoic rim's characteristics allows one to evaluate the efficacy of RFA.

Imaging detection of new HCCs in cirrhotic patients treated with different techniques: Comparison of conventional US, spiral CT, and 3-dimensional contrast-enhanced US with the Navigator technique (Nav 3D CEUS)()

INTRODUCTION

The commercially available Navigator system(©) (Esaote, Italy) allows easy 3D reconstruction of a single 2D acquisition of contrast-enhanced US (CEUS) imaging of the whole liver (with volumetric correction provided by the electromagnetic device of the Navigator(©)). The aim of our study was to compare the efficacy of this panoramic technique (Nav 3D CEUS) with that of conventional US and spiral CT in the detection of new hepatic lesions in patients treated for hepatocellular carcinoma (HCC).

MATERIALS AND METHODS

From November 2006 to May 2007, we performed conventional US, Nav 3D CEUS, and spiral CT on 72 cirrhotic patients previously treated for 1 or more HCCs (M/F: 38/34; all HCV-positive; Child: A/B 58/14) (1 examination: 48 patients; 2 examinations: 20 patients; 3 examinations: 4 patients). Nav 3D CEUS was performed with SonoVue(©) (Bracco, Milan, Italy) as a contrast agent and Technos MPX(©) scanner (Esaote, Genoa, Italy). Sensitivity, specificity, diagnostic accuracy, and positive and negative predictive values (PPV and NPV, respectively) were evaluated. Differences between the techniques were assessed with the chi-square test (SPSS release-15).

RESULTS

Definitive diagnoses (based on spiral CT and additional follow-up) were: 6 cases of local recurrence (LocRecs) in 4 patients, 49 new nodules >2 cm from a treated nodule (NewNods) in 34 patients, and 10 cases of multinodular recurrence consisting of 4 or more nodules (NewMulti). The remaining 24 patients (22 treated for 1-3 nodules, 2 treated for >3 nodules) remained recurrence-free. Conventional US correctly detected 29/49 NewNods, 9/10 NewMultis, and 3/6 LocRecs (sensitivity: 59.2%; specificity: 100%; diagnostic accuracy: 73.6%; PPV: 100%; NPV: 70.1%). Spiral CT detected 42/49 NewNods plus 1 that was a false positive, 9/10 NewMultis, and all 6 LocRecs (sensitivity: 85.7%; specificity: 95.7%; diagnostic accuracy: 90.9%; PPV: 97.7%; NPV: 75.9%). 3D NAV results were: 46N (+9 multinodularN and 6 LR), 3 false-negatives, and one false-positive (sensitivity: 93.9; specificity: 97.9%; diagnostic accuracy: 95.6; PPV: 97.9; NPV: 93.9).

CONCLUSIONS

3D Nav CEUS is significantly better than US and very similar to spiral CT for detection of new HCCs. This technique revealed the presence of lesions that could not be visualized with spiral CT.

Hepatocellular cancer response to radiofrequency tumor ablation: contrast-enhanced ultrasound

Radiofrequency ablation (RFA) is increasingly being used as percutaneous treatment of choice for patients with early stage hepatocellular carcinoma (HCC). An accurate assessment of the RFA therapeutic response is of crucial importance, considering that a complete tumor ablation significantly increases patient survival, whereas residual unablated tumor calls for additional treatment. Imaging modalities play a pivotal role in accomplishing this task, but ultrasound (US) is not considered a reliable modality for the evaluation of the real extent of necrosis, even when color/power Doppler techniques are used. Recently, newer microbubble-based US contrast agents used in combination with grey-scale US techniques, which are very sensitive to non-linear behavior of microbubbles, have been introduced. These features have opened new prospects in liver ultrasound and may have a great impact on daily practice, including cost-effective assessment of therapeutic response of percutaneous ablative therapies. Technical evolution of CEUS focusing on findings after RFA are illustrated. These latter are detailed, cross-referenced with the literature and discussed on the basis of our personal experience. Timing of CEUS posttreatment assessment among with advantages and limitations of CEUS are also described with a perspective on further technologic refinement.

Risk factors and prognostic factors of local recurrence after radiofrequency ablation of hepatocellular carcinoma

BACKGROUND

Local recurrence rates after radiofrequency ablation (RFA) of hepatocellular carcinoma (HCC) vary from 2% to 36% in the literature. Limited data were available about the prognostic significance of local recurrence.

STUDY DESIGN

Between April 2001 and March 2006, 273 patients with 357 hepatocellular carcinoma nodules underwent RFA, with radiologically complete tumor ablation after a single session of RFA. The risk factors of local recurrence and its impact on overall survival of patients were analyzed.

RESULTS

With a median followup period of 24 months, local recurrence occurred in 35 patients (12.8%). By multivariate analysis, tumor size > 2.5 cm was the only independent risk factor for local recurrence. There was no notable difference in overall survival between patients with and without local recurrence. By multivariate analysis, local recurrence more than 12 months after RFA and complete response after additional treatment of local recurrence were associated with better overall survival in patients with local recurrence.

CONCLUSIONS

This study demonstrated that tumor size > 2.5 cm was the main risk factor for local recurrence after RFA of hepatocellular carcinoma. Our data suggested that additional aggressive treatment of local recurrence aimed at complete tumor response improves overall survival of patients. Late local recurrence was also associated with better prognosis, suggesting different tumor biology between early and late local recurrent tumors after RFA.

Radiological diagnosis of hepatocellular carcinoma

Treatment of hepatocellular carcinomas (HCC) is often complicated by the fact that early HCCs are mostly asymptomatic and the carcinoma is often discovered at an advanced stage. The aim of diagnostic imaging is to detect HCC at an early stage, when curative options are available. In recent years, there have been many efforts to improve early detection of small HCC. The purpose of this article is to describe the pertinent findings of HCCs in non-invasive, diagnostic imaging, including ultrasound, computed tomography, as well as modern magnetic resonance imaging techniques. Special emphasis is given to the frequently addressed difficulties of differentiation of precancerous lesions and small HCCs. A non-invasive diagnostic approach is considered with a review of the literature.

Incomplete ablation after radiofrequency ablation of hepatocellular carcinoma: analysis of risk factors and prognostic factors

BACKGROUND

Complete ablation rates after a single session of radiofrequency ablation (RFA) of hepatocellular carcinoma (HCC) vary from 48% to 97%. Limited data are available regarding risk factors and prognostic significance of incomplete ablation.

METHODS

Between April 2001 and March 2006, 298 patients underwent RFA of 393 HCC nodules with an intent of complete ablation after a single session. Risk factors for incomplete ablation and its effect on overall survival were analyzed.

RESULTS

Two hundred seventy-three (91.6%) underwent complete tumor ablation, whereas the other 25 (8.4%) underwent incomplete tumor ablation after a single session of RFA. By multivariate analysis, tumor size > 3 cm (P = .049) was found to be the only independent risk factor for incomplete ablation. There was no statistically significant difference in overall survival between patients with complete and incomplete ablation. By univariate analysis, no previous transarterial chemoembolization (TACE), preoperative serum alfa-fetoprotein < or = 100 microg/mL, and complete response after further treatment of incomplete ablation were associated with better overall survival in patients with incomplete ablation.

CONCLUSIONS

This study demonstrated that incomplete ablation after RFA of HCC was associated with tumor size > 3 cm. Our data also suggest that aggressive further treatment of tumors with incomplete ablation aiming at complete tumor response improves overall survival.