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

The American College of Radiology contrast-enhanced ultrasound Liver Imaging Reporting and Data System and its modified version in diagnosing hepatocellular carcinoma via Sonazoid: a meta-analysis

Background

The American College of Radiology (ACR) developed the contrast-enhanced ultrasound (CEUS) Liver Imaging Reporting and Data System (LI-RADS) for pure blood contrast agents, but Sonazoid was not included. Modifications to LI-RADS have been proposed for Sonazoid. The purpose of this meta-analysis was to identify and compare the diagnostic efficacy of the two LI-RADS algorithms of Sonazoid.

Methods

We searched the PubMed, MEDLINE, Web of Science, Embase, and Cochrane Library databases from databases inception to August 31, 2023, to find original studies on the ACR LI-RADS and/or modified LI-RADS algorithm with Sonazoid used as the contrast agent in patients with high-risk hepatocellular carcinoma (HCC). A bivariate random-effects model was used. Data pooling, meta-regression, and sensitivity analysis were performed for meta-analysis. The Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) tool was used to assess the methodological quality, and the Deeks funnel plot asymmetry test was used to evaluate the publication bias.

Results

A meta-analysis of 10 studies with 1,611 observations was conducted. The pooled data for ACR LI-RADS category 5 (LR-5) and modified LR-5 were respectively as follows: pooled sensitivity, 0.70 [95% confidence interval (CI): 0.64-0.75] and 0.81 (95% CI: 0.76-0.86) (P<0.05); pooled specificity, 0.90 (95% CI: 0.82-0.94) and 0.87 (95% CI: 0.81-0.91) (P>0.05); and pooled area under the summary receiver operating characteristic curve, 0.84 and 0.91. The diagnostic performance of LI-RADS category M (LR-M) of the two algorithms was comparable. Study heterogeneity was observed.

Conclusions

The results indicated that modified LR-5 algorithm demonstrated improved diagnostic sensitivity compared with the ACR LR-5 algorithm of Sonazoid, with differences observed between the different versions. Further research is needed to validate and explore the optimal diagnostic criteria for HCC using Sonazoid. Before the database search was conducted, this study was registered on PROSPERO (International Prospective Register of Systematic Reviews; CRD42023455220).

Contrast-Enhanced Ultrasonography in Diagnosing Intravascular Large B-Cell Lymphoma Infiltrating Liver Sinusoids

BACKGROUND Intravascular large B-cell lymphoma (IVLBCL) is a rare extranodal large B-cell lymphoma characterized by the selective growth of lymphoma cells within vasculature. This presents a diagnostic challenge due to non-specific symptoms and lack of tumor formation. 18F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) provides useful information in diagnosing FDG-avid lymphoma, but is not specific to  IVLBCL. Contrast-enhanced ultrasonography (CEUS) is useful in evaluating focal liver lesions; however, its efficacy in diagnosing IVLBCL involving the liver remains unknown. CASE REPORT We report the case of an 83-year-old woman presenting with fever, pancytopenia, liver dysfunction, and elevated LD and soluble interleukin-2 receptor levels. PET-CT showed multiple uptake lesions in the liver. We performed CEUS with Sonazoid® to evaluate the mass-like lesions; however, no nodular lesions were observed in B mode images. Systemic enhancement was seen in the early phase but no defect was observed in the post-vascular phase. The latter finding suggested preserved Kupffer cells function, excluding tumor-forming lymphoma and liver metastases. Suspecting IVLBCL, we performed a bone marrow examination, which showed sinusoidal infiltration of large neoplastic cells positive for CD20. The patient's condition deteriorated rapidly and she died 2 days after the examination. Autopsy revealed diffuse infiltration of lymphoma cells into liver sinusoids with preserved Kupffer cells, leading to the diagnosis of IVLBCL. CONCLUSIONS Our case shows that CEUS can distinguish IVLBCL from mass-forming lymphoma based on the absence of a defect in the post-vascular phase in a patient with clinically and radiographically suspected lymphoma involving the liver. This can assist clinicians to select appropriate lesions for biopsy.

Contrast-enhanced ultrasound with microbubbles containing sulfur hexafluoride and perfluorobutane with Kupffer phase for the detection of colorectal liver metastases

OBJECTIVE

To compare contrast-enhanced ultrasound (CEUS) with microbubbles containing sulfur hexafluoride (SHF) and perfluorobutane (PFB) for the detection of colorectal liver metastasis (CRLM).

METHODS

In this prospective study, conducted from September to November 2021, patients with colorectal cancer were consecutively recruited and underwent same-day ultrasound, SHF-CEUS, and PFB-CEUS. The reference standard was contrast-enhanced MRI and follow-up imaging. The size, depth, echogenicity, and calcification of each focal liver lesion were recorded. The number and conspicuity of CRLMs, based on washout appearance during the late phase (LP) (> 120 s)/Kupffer phase (KP), were evaluated offsite by two blinded readers.

RESULTS

Overall, 230 lesions (CRLMs, n = 219; benign lesions, n = 11) in 78 patients were evaluated. Lesion conspicuity (p = 0.344) and accuracy in the detection of CRLM were comparable for SHF- and PFB-CEUS (0.877 for SHF vs. 0.770 for PFB, p = 0.087). More CRLMs ≥ 10 mm were identified by LP contrast washout in SHF-CEUS than in KP PFB-CEUS (p < 0.001). More CRLMs < 10 mm were identified by KP washout in PFB-CEUS than in LP SHF-CEUS (p < 0.001). Conspicuity was better on PFB-CEUS than on SHF-CEUS (p = 0.027). In hyperechoic lesions, lesions located deeper than 80 mm, and calcified lesions, CRLM conspicuity on PFB-CEUS was inferior to that on SHF-CEUS (p < 0.05).

CONCLUSIONS

The overall accuracy of detection and conspicuity of washout in CRLMs were comparable between SHF and PFB-CEUS. PFB-CEUS has the advantage of identifying washout in small CRLMs. However, larger, hyperechogenic, deep-seated, or calcified lesions were better identified using SHF-CEUS.

CLINICAL RELEVANCE STATEMENT

Accuracy of detection and conspicuity of washout in CRLMs were comparable between SHF- and PFB-CEUS. PFB-CEUS has the advantage in detecting small CRLMs, whereas SHF-CEUS is better for detecting larger, hyperechogenic, deep-seated, or calcified lesions.

KEY POINTS

Contrast-enhanced ultrasound with sulfur hexafluoride in the late phase and perfluorobutane microbubbles in the Kupffer phase were comparable in terms of accuracy in the detection and conspicuity of colorectal liver metastases. Small colorectal liver metastases (< 10 mm) were more often identified in the Kupffer phase contrast-enhanced ultrasound imaging when using perfluorobutane microbubbles. Larger, hyperechogenic, deep-seated, or calcified lesions were better identified in the late phase contrast-enhanced ultrasound imaging (> 120 s) when using sulfur hexafluoride microbubbles.

Deep learning approach for discrimination of liver lesions using nine time-phase images of contrast-enhanced ultrasound

PURPOSE

Contrast-enhanced ultrasound (CEUS) shows different enhancement patterns depending on the time after administration of the contrast agent. The aim of this study was to evaluate the diagnostic performance of liver nodule characterization using our proposed deep learning model with input of nine CEUS images.

METHODS

A total of 181 liver lesions (48 benign, 78 hepatocellular carcinoma (HCC), and 55 non-HCC malignant) were included in this prospective study. CEUS were performed using the contrast agent Sonazoid, and in addition to B-mode images before injection, image clips were stored every minute up to 10 min. A deep learning model was developed by arranging three ResNet50 transfer learning models in parallel. This proposed model allowed inputting up to nine datasets of different phases of CEUS and performing image augmentation of nine images synchronously. Using the results, the correct prediction rate, sensitivity, and specificity between "benign" and "malignant" cases were analyzed for each combination of the time phase. These accuracy values were also compared with the washout score judged by a human.

RESULTS

The proposed model showed performance superior to the referential standard model when the dataset from B-mode to the 10-min images were used (sensitivity: 93.2%, specificity: 65.3%, average correct answer rate: 60.1%). It also maintained 90.2% sensitivity and 61.2% specificity even when the dataset was limited to 2 min after injection, and this accuracy was equivalent to or better than human scoring by experts.

CONCLUSION

Our proposed model has the potential to identify tumor types earlier than the Kupffer phase, but at the same time, machine learning confirmed that Kupffer-phase Sonazoid images contain essential information for the classification of liver nodules.

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.

Usefulness of contrast-enhanced ultrasonography for biliary tract disease

Conventional ultrasonography (US) for biliary tract disease shows high time and spatial resolution. In addition, it is simple and minimally invasive, and is selected as a first-choice examination procedure for biliary tract disease. Currently, contrast-enhanced US (CEUS), which facilitates the more accurate assessment of lesion blood flow in comparison with color and power Doppler US, is performed using a second-generation ultrasonic contrast agent. Such agents are stable and provide a timeline for CEUS diagnosis. Gallbladder lesions are classified into three types: gallbladder biliary lesion (GBL), gallbladder polypoid lesion (GPL), and gallbladder wall thickening (GWT). Bile duct lesions can also be classified into three types: bile duct biliary lesion (BBL), bile duct polypoid lesion (BDPL), and bile duct wall thickening (BDWT). CEUS facilitates the differentiation of GBL/BBL from tumorous lesions based on the presence or absence of blood vessels. In the case of GPL, it is important to identify a vascular stalk attached to the lesion. In the case of GWT, the presence or absence of a non-contrast-enhanced area, the Rokitansky-Aschoff sinus, and continuity of a contrast-enhanced gallbladder wall layer are important for differentiation from gallbladder cancer. In the case of BDWT, it is useful to evaluate the contour of the contrast-enhanced medial layer of the bile duct wall for differentiating IgG4-related sclerosing cholangitis from primary sclerosing cholangitis. CEUS for ampullary carcinoma accurately reflects histopathological findings of the lesion. Evaluating blood flow in the lesion, continuity of the gallbladder wall, and contour of the bile duct wall via CEUS provides useful information for the diagnosis of biliary tract disease.

[Contrast-enhanced ultrasonography with intra-glandular contrast injection can improve the diagnostic accuracy of central compartment lymph node metastasis of thyroid cancer]

OBJECTIVE

To investigate the value of lymphatic contrast-enhanced ultrasound (LCEUS) with intra-glandular injection of contrast agent for diagnosis of central compartment lymph node metastasis of thyroid cancer.

METHODS

From November, 2020 to May, 2022, the patients suspected of having thyroid cancer and scheduled for biopsy at our center received both conventional ultrasound and LCEUS examinations of the central compartment lymph nodes before surgery. All the patients underwent surgical dissection of the lymph nodes. The perfusion features in LCEUS were classified as homogeneous enhancement, heterogeneous enhancement, regular/irregular ring, and non-enhancement. With pathological results as the gold standard, we compared the diagnostic ability of conventional ultrasound and LCEUS for identifying metastasis in the central compartment lymph nodes.

RESULTS

Forty-nine patients with 60 lymph nodes were included in the final analysis. Pathological examination reported metastasis in 34 of the lymph nodes, and 26 were benign lymph nodes. With ultrasound findings of heterogeneous enhancement, irregular ring and non-enhancement as the criteria for malignant lesions, LCEUS had a diagnostic sensitivity, specificity and accuracy of 97.06%, 92.31% and 95% for diagnosing metastatic lymph nodes, respectively, demonstrating its better performance than conventional ultrasound (P < 0.001). Receiver-operating characteristic curve analysis showed that LCEUS had a significantly greater area under the curve than conventional ultrasound for diagnosing metastatic lymph nodes (94.7% [0.856-0.988] vs 78.2% [0.656-0.878], P=0.003).

CONCLUSION

LCEUS can enhance the display and improve the diagnostic accuracy of the central compartment lymph nodes to provide important clinical evidence for making clinical decisions on treatment of thyroid cancer.

Ultrasound contrast agents: microbubbles made simple for the pediatric radiologist

The ability to provide prompt, real-time, easily accessible and radiation-free diagnostic assessments makes ultrasound (US) one of the most versatile imaging modalities. The introduction and development of stable microbubble-based ultrasound contrast agents (UCAs) in the early 1990s improved visualization of complex vascular structures, overcoming some of the limitations of B-mode and Doppler imaging. UCAs have been used extensively in the adult population to visualize vasculature and to evaluate perfusion and blood flow dynamics in organs and lesions. Since the first observations that air bubbles within a liquid can generate a strong echogenic effect, to the early makeshift approaches with agitated saline, and later to the development of industrially produced and federally approved UCAs, these agents have evolved to become both clinically and commercially viable. Perhaps the most exciting potential of UCAs is being uncovered by current research that explores the use of these agents for molecular imaging and therapeutic applications. As contrast-enhanced ultrasound (CEUS) becomes more widely available, it is important for pediatric radiologists to understand the physics of the interaction between the US signal and the microbubbles in order to properly utilize them for the highest level of diagnostic imaging and interventions. In this article we introduce the composition of UCAs and the physics of their behavior in US, and we offer a brief history of their development over the last decades.

Perfluorobutane contrast-enhanced ultrasonography for the diagnosis of HCC: a systematic review and meta-analysis

OBJECTIVES

Perfluorobutane ultrasound contrast agent as a new type of contrast agent has a good performance in the diagnosis of hepatocellular carcinoma (HCC). This study aim to evaluate the accuracy and reliability of Perfluorobutane contrast-enhanced ultrasonography (P-CEUS) in the diagnosis of HCC with a systematic review and meta-analysis.

METHODS

Web of Science, EMBASE, Cochrane, Clinical Key, Wan Fang, CBM and CNKI databases were systematically searched and checked for studies using P-CEUS in HCC, from 2007 to 2020. Data necessary to construct 2 × 2 contingency tables were extracted from included studies. The QUADAS tool was utilized to assess the methodologic quality of the studies. Meta-analysis included data pooling, subgroup analyses, meta-regression and investigation of publication bias was comprehensively performed.

RESULTS

Nine studies were included in this meta-analysis and the overall diagnostic accuracy in characterization of HCC was as follows: pooled sensitivity, 0.90 (95% confidence interval: 0.82-0.95); pooled specificity, 0.97 (0.93-0.98); pooled positive likelihood ratio, 27.2 (14.1 to - 52.3); and pooled negative likelihood ratio, 0.10 (0.06-0.18). The area under the comprehensive receiving operation characteristic curve was 0.98 (0.97-0.99).

CONCLUSION

The sensitivity and specificity of P-CEUS are more valuable than other imaging techniques (such as computer tomography or magnetic resonance imaging). However, due to the large differences in the data samples collected in this study, statistical heterogeneity results. P-CEUS can significantly improve the diagnostic efficiency of previous contrast-enhanced ultrasound for HCC. PROSPERO registration number: PROSPERO (CRD42020200040).

AI-Based Radiological Imaging for HCC: Current Status and Future of Ultrasound

Hepatocellular carcinoma (HCC) is a common cancer worldwide. Recent international guidelines request an identification of the stage and patient background/condition for an appropriate decision for the management direction. Radiomics is a technology based on the quantitative extraction of image characteristics from radiological imaging modalities. Artificial intelligence (AI) algorithms are the principal axis of the radiomics procedure and may provide various results from large data sets beyond conventional techniques. This review article focused on the application of the radiomics-related diagnosis of HCC using radiological imaging (computed tomography, magnetic resonance imaging, and ultrasound (B-mode, contrast-enhanced ultrasound, and elastography)), and discussed the current role, limitation and future of ultrasound. Although the evidence has shown the positive effect of AI-based ultrasound in the prediction of tumor characteristics and malignant potential, posttreatment response and prognosis, there are still a number of issues in the practical management of patients with HCC. It is highly expected that the wide range of applications of AI for ultrasound will support the further improvement of the diagnostic ability of HCC and provide a great benefit to the patients.