CEUS LI-RADS: algorithm, implementation, and key differences from CT/MRI

Contrast-enhanced ultrasound for the diagnosis of hepatocellular carcinoma in adults with chronic liver disease

BACKGROUND

Hepatocellular carcinoma occurs mostly in people with chronic liver disease. Worldwide, it ranks sixth in terms of incidence of cancer, and fourth in terms of cancer-related deaths. Contrast-enhanced ultrasound (CEUS) is used as an add-on test to confirm the presence of focal liver lesions suspected as hepatocellular carcinoma after prior diagnostic tests such as abdominal ultrasound or measurement of alpha-foetoprotein, or both. According to guidelines, a single contrast-enhanced imaging investigation, with either computed tomography (CT) or magnetic resonance imaging (MRI), may show the typical hepatocellular carcinoma hallmarks in people with cirrhosis, which will be sufficient to diagnose hepatocellular carcinoma. However, a significant number of hepatocellular carcinomas show atypical imaging features, and therefore, are missed at imaging. Dynamic CEUS images are obtained similarly to CT and MRI images. CEUS differentiates between arterial and portal venous phases, in which sonographic hepatocellular carcinoma hallmarks, such as arterial hyperenhancement and subsequent washout appearance, are investigated. The advantages of CEUS over CT and MRI include real-time imaging, use of contrast agents that do not contain iodine and are not nephrotoxic, and quick image acquisition. Despite the advantages, the use of CEUS in the diagnostic algorithm for HCC remains controversial, with disagreement on relevant guidelines. There is no clear evidence of the benefit of surveillance programmes in terms of overall survival as the conflicting results can be a consequence of an inaccurate detection, ineffective treatment, or both. Therefore, assessing the diagnostic accuracy of CEUS may clarify whether the absence of benefit could be related to underdiagnosis. Furthermore, an assessment of the accuracy of CEUS for the diagnosis of hepatocellular carcinoma is needed for either diagnosing hepatocellular carcinoma or ruling it out in people with chronic liver disease who are not included in surveillance programmes.

OBJECTIVES

1. To assess the diagnostic accuracy of contrast-enhanced ultrasound (CEUS) for the diagnosis of hepatocellular carcinoma of any size and at any stage in adults with chronic liver disease, in a surveillance programme or in a clinical setting. 2. To assess the diagnostic accuracy of CEUS for the diagnosis of resectable hepatocellular carcinoma in people with chronic liver disease and identify potential sources of heterogeneity in the results.

SEARCH METHODS

We used standard, extensive Cochrane search methods. The last date of search was 5 November 2021.

SELECTION CRITERIA

We included studies assessing the diagnostic accuracy of CEUS for the diagnosis of hepatocellular carcinoma in adults with chronic liver disease, with cross-sectional designs, using one of the acceptable reference standards, such as pathology of the explanted liver, and histology of resected or biopsied focal liver lesion with at least a six-month follow-up.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods to screen studies, extract data, and assess the risk of bias and applicability concerns, using the QUADAS-2 checklist. We used the bivariate model and provided estimates of summary sensitivity and specificity. We assessed the certainty of the evidence using GRADE. We presented uncertainty-of-the-accuracy estimates using 95% confidence intervals (CIs).

MAIN RESULTS

We included 23 studies with 6546 participants. Studies were published between 2001 and 2021. We judged all 23 studies at high-risk of bias in at least one domain, and 13/23 studies at high concern for applicability. Most studies used different reference standards to exclude the presence of the target condition. The time interval between the index test and the reference standard was rarely defined. We also had major concerns on their applicability due to the characteristics of the participants. - CEUS for hepatocellular carcinoma of any size and stage: sensitivity 77.8% (95% CI 69.4% to 84.4%) and specificity 93.8% (95% CI 89.1% to 96.6%) (23 studies, 6546 participants; very low-certainty evidence). - CEUS for resectable hepatocellular carcinoma: sensitivity 77.5% (95% CI 62.9% to 87.6%) and specificity 92.7% (95% CI 86.8% to 96.1%) (13 studies, 1257 participants; low-certainty evidence). The observed heterogeneity in the results remains unexplained. The sensitivity analyses, including only studies with clearly prespecified positivity criteria and only studies in which the reference standard results were interpreted with no knowledge of the results about the index test, showed no differences in the results.

AUTHORS' CONCLUSIONS

We found that by using CEUS, as an add-on test following abdominal ultrasound, to diagnose hepatocellular carcinoma of any size and stage, 22% of people with hepatocellular carcinoma would be missed, and 6% of people without hepatocellular carcinoma would unnecessarily undergo further testing or inappropriate treatment. As to resectable hepatocellular carcinoma, we found that 23% of people with resectable hepatocellular carcinoma would incorrectly be unresected, while 8% of people without hepatocellular carcinoma would undergo further inappropriate testing or treatment. The uncertainty resulting from the high risk of bias of the included studies, heterogeneity, and imprecision of the results and concerns on their applicability limit our ability to draw confident conclusions.

Profiling hepatocellular carcinoma aggressiveness with contrast-enhanced ultrasound and gadoxetate disodium-enhanced MRI: An intra-individual comparative study based on the Liver Imaging Reporting and Data System

PURPOSE

Contrast-enhanced ultrasound (CEUS) and gadoxetate disodium-enhanced MRI (EOB-MRI) may synergize in profiling hepatocellular carcinoma (HCC) aggressiveness considering distinct imaging traits. This study aimed to intra-individually compare CEUS and EOB-MRI with Liver Imaging Reporting and Data System (LI-RADS) in assessing HCC aggressiveness.

METHOD

From January 2015 to November 2020, consecutive at-risk patients with surgically-confirmed HCC who underwent both preoperative CEUS and EOB-MRI examinations were retrospectively enrolled. Image analyses were conducted independently by two masked radiologists for CEUS and EOB-MRI, respectively. The diagnostic performance of each modality for macrovascular invasion against pathology was evaluated and compared with the McNemar's test, while Edmondson-Steiner grade and the presence of microvascular invasion (MVI) were compared between patients with and without LR-M features on each modality.

RESULTS

A total of 140 patients (mean age, 51.9 years ± 11.0; 116 men) were included. Inter-modality agreement was poor (κ = -0.087 ∼ 0.139) for major LI-RADS features and moderate (κ = 0.449) for overall LI-RADS categorization, and LR-TIV and LR-M were the top sources of inter-modality variations. Although CEUS demonstrated significantly higher specificity for diagnosing macrovascular invasion (96% vs. 89%, P =.02), LR-M features on EOB-MRI were more effective in identifying higher Edmondson-Steiner grades (P =.01) and MVI (P =.02).

CONCLUSIONS

Marked discrepancies were found between CEUS and EOB-MRI in evaluating LI-RADS features and categories. Whereas CEUS showed superior diagnostic specificity for macrovascular invasion, LR-M features on EOB-MRI provided more information regarding tumor grade and MVI status in HCC patients.

Clinical value of contrast-enhanced ultrasound in early diagnosis of small hepatocellular carcinoma (≤ 2 cm)

BACKGROUND

Hepatocellular carcinoma (HCC) is the most common type of primary liver malignancy. Contrast-enhanced ultrasound (CEUS) uses contrast microbubbles during ultrasound, allowing the detection and characterization of malignant focal liver lesions with much higher diagnostic accuracy than conventional ultrasound; however, there are few reports focusing on the pattern of enhancement of CEUS for the diagnosis of HCC smaller than 2 cm.

AIM

To investigate the clinical value of CEUS in the early detection of small HCC with high risk factors.

METHODS

A total of 395 patients with 632 nodules at high risk of HCC, who underwent regular follow-up at Xuhui Dahua Hospital from January 2007 to December 2021, were retrospectively examined. Conventional ultrasonography combined with CEUS was adopted to analyze the echo, size, location, and enhancement characteristics of benign and malignant nodules, as well as the enhancement methods for HCC with different diameters.

RESULTS

The follow-up rate and duration were 92.15% (364/395) and 51.28 ± 45.09 mo, respectively. Conventional ultrasonography combined with CEUS revealed 65 (11.80%) nodules with a follow-up diagnosis of HCC, 19 (3.45%) dysplastic nodules, and 467 (84.75%) benign cirrhotic hyperplastic nodules. Among 65 cases of confirmed HCC, 40 (61.54%) were transformed from hypoechoic nodules, 9 (13.85%) from hyperechoic nodules, and the remaining 16 (24.62%) from isoechoic nodules. Significant differences in CEUS characteristics were found among cirrhotic nodules, dysplastic nodules, and HCC nodules at each phase. Significant differences in the enhancement mode were observed between nodules ≤ 1 cm and those 1-2 cm. The smaller the HCC nodule, the later the contrast agent began to flush and the longer the duration of contrast enhancement.

CONCLUSION

Conventional ultrasonography combined with CEUS could identify small HCC and help monitor patients with an early diagnosis of HCC. Significant differences in the enhancement mode are noted between nodules ≤ 1 cm and those 1-2 cm.

Microbubbles in the belly: optimizing the protocol for contrast-enhanced ultrasound of the pediatric abdomen

Intravenous contrast-enhanced ultrasound (CEUS) can serve as a diagnostic or problem-solving tool in pediatric imaging. CEUS of abdominal solid organs has been reported for a number of indications. The approach to the examination broadly falls into two categories: evaluation of a focal lesion or surveillance of an organ or organs for lesions or perfusion abnormalities. A consistent, technical imaging protocol for both of these clinical scenarios facilitates integration of routine use of CEUS in an imaging department. Here we review the CEUS imaging protocols for abdominal organs in children, including technical and solid-organ-specific considerations.

Correlation between quantitative parameters of CEUS and Ki-67 labeling index in soft-tissue sarcoma

BACKGROUND

Apart from the immunohistochemical Ki-67 labeling index (LI), clinicians need a non-invasive and convenient way to predict the prognosis of patients with soft-tissue sarcoma (STS).

PURPOSE

To investigate the correlation between quantitative parameters of contrast-enhanced ultrasound (CEUS) and Ki-67 LI in STS.

MATERIAL AND METHODS

A total of 25 patients diagnosed with STS who underwent CEUS examination using SonoVue®, between January 2019 to November 2020, were included in the study. They were then divided into a high-proliferation group and low-proliferation group according to 30% Ki-67 positive tumor cells. The quantitative parameters in the semi-automatic time intensity curve analysis software, including arrival time, time to peak, peak intensity, rise time (RT), rise slope, 50% wash-out time, and 50% wash-out intensity, were extracted from the time intensity curve of CEUS by two independent observers. Statistical evaluation of the correlation and difference between CEUS quantitative parameters and Ki-67 LI between the two groups was performed. According to the area under the curve (AUC) analysis, optimal cutoff points of parameters with significant difference were determined.

RESULTS

CEUS RT of the high-proliferation group in STS was significantly higher than that of the low-proliferation group (ρ = 0.509, P = 0.01). The most reasonable cutoff to distinguish between low- and high-proliferation groups was 10.84 s. The sensitivity, specificity, and the AUC were 86.7%, 80%, and 0.80, respectively.

CONCLUSION

CEUS RT was correlated with Ki-67 LI of STS, which can be used as a minimally invasive auxiliary tool to predict the prognosis of STS in clinical practice.

Contrast-enhanced ultrasound Liver Imaging Reporting and Data System: Lights and shadows in hepatocellular carcinoma and cholangiocellular carcinoma diagnosis

BACKGROUND

Contrast-enhanced ultrasound (CEUS) is considered a secondary examination compared to computed tomography (CT) and magnetic resonance imaging (MRI) in the diagnosis of hepatocellular carcinoma (HCC), due to the risk of misdiagnosing intrahepatic cholangiocarcinoma (ICC). The introduction of CEUS Liver Imaging Reporting and Data System (CEUS LI-RADS) might overcome this limitation. Even though data from the literature seems promising, its reliability in real-life context has not been well-established yet.

AIM

To test the accuracy of CEUS LI-RADS for correctly diagnosing HCC and ICC in cirrhosis.

METHODS

CEUS LI-RADS class was retrospectively assigned to 511 nodules identified in 269 patients suffering from liver cirrhosis. The diagnostic standard for all nodules was either biopsy (102 nodules) or CT/MRI (409 nodules). Common diagnostic accuracy indexes such as sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were assessed for the following associations: CEUS LR-5 and HCC; CEUS LR-4 and 5 merged class and HCC; CEUS LR-M and ICC; and CEUS LR-3 and malignancy. The frequency of malignant lesions in CEUS LR-3 subgroups with different CEUS patterns was also determined. Inter-rater agreement for CEUS LI-RADS class assignment and for major CEUS pattern identification was evaluated.

RESULTS

CEUS LR-5 predicted HCC with a 67.6% sensitivity, 97.7% specificity, and 99.3% PPV (P < 0.001). The merging of LR-4 and 5 offered an improved 93.9% sensitivity in HCC diagnosis with a 94.3% specificity and 98.8% PPV (P < 0.001). CEUS LR-M predicted ICC with a 91.3% sensitivity, 96.7% specificity, and 99.6% NPV (P < 0.001). CEUS LR-3 predominantly included benign lesions (only 28.8% of malignancies). In this class, the hypo-hypo pattern showed a much higher rate of malignant lesions (73.3%) than the iso-iso pattern (2.6%). Inter-rater agreement between internal raters for CEUS-LR class assignment was almost perfect (n = 511, k = 0.94, P < 0.001), while the agreement among raters from separate centres was substantial (n = 50, k = 0.67, P < 0.001). Agreement was stronger for arterial phase hyperenhancement (internal k = 0.86, P < 2.7 × 10-214; external k = 0.8, P < 0.001) than washout (internal k = 0.79, P < 1.6 × 10-202; external k = 0.71, P < 0.001).

CONCLUSION

CEUS LI-RADS is effective but can be improved by merging LR-4 and 5 to diagnose HCC and by splitting LR-3 into two subgroups to differentiate iso-iso nodules from other patterns.

A Narrative Review on LI-RADS Algorithm in Liver Tumors: Prospects and Pitfalls

Liver cancer is the sixth most detected tumor and the third leading cause of tumor death worldwide. Hepatocellular carcinoma (HCC) is the most common primary liver malignancy with specific risk factors and a targeted population. Imaging plays a major role in the management of HCC from screening to post-therapy follow-up. In order to optimize the diagnostic-therapeutic management and using a universal report, which allows more effective communication among the multidisciplinary team, several classification systems have been proposed over time, and LI-RADS is the most utilized. Currently, LI-RADS comprises four algorithms addressing screening and surveillance, diagnosis on computed tomography (CT)/magnetic resonance imaging (MRI), diagnosis on contrast-enhanced ultrasound (CEUS) and treatment response on CT/MRI. The algorithm allows guiding the radiologist through a stepwise process of assigning a category to a liver observation, recognizing both major and ancillary features. This process allows for characterizing liver lesions and assessing treatment. In this review, we highlighted both major and ancillary features that could define HCC. The distinctive dynamic vascular pattern of arterial hyperenhancement followed by washout in the portal-venous phase is the key hallmark of HCC, with a specificity value close to 100%. However, the sensitivity value of these combined criteria is inadequate. Recent evidence has proven that liver-specific contrast could be an important tool not only in increasing sensitivity but also in diagnosis as a major criterion. Although LI-RADS emerges as an essential instrument to support the management of liver tumors, still many improvements are needed to overcome the current limitations. In particular, features that may clearly distinguish HCC from cholangiocarcinoma (CCA) and combined HCC-CCA lesions and the assessment after locoregional radiation-based therapy are still fields of research.

Deep Learning of Liver Contrast-Enhanced Ultrasound to Predict Microvascular Invasion and Prognosis in Hepatocellular Carcinoma

Background and Aims

Microvascular invasion (MVI) is a well-known risk factor for poor prognosis in hepatocellular carcinoma (HCC). This study aimed to develop a deep convolutional neural network (DCNN) model based on contrast-enhanced ultrasound (CEUS) to predict MVI, and thus to predict prognosis in patients with HCC.

Methods

A total of 436 patients with surgically resected HCC who underwent preoperative CEUS were retrospectively enrolled. Patients were divided into training (n = 301), validation (n = 102), and test (n = 33) sets. A clinical model (Clinical model), a CEUS video-based DCNN model (CEUS-DCNN model), and a fusion model based on CEUS video and clinical variables (CECL-DCNN model) were built to predict MVI. Survival analysis was used to evaluate the clinical performance of the predicted MVI.

Results

Compared with the Clinical model, the CEUS-DCNN model exhibited similar sensitivity, but higher specificity (71.4% vs. 38.1%, p = 0.03) in the test group. The CECL-DCNN model showed significantly higher specificity (81.0% vs. 38.1%, p = 0.005) and accuracy (78.8% vs. 51.5%, p = 0.009) than the Clinical model, with an AUC of 0.865. The Clinical predicted MVI could not significantly distinguish OS or RFS (both p > 0.05), while the CEUS-DCNN predicted MVI could only predict the earlier recurrence (hazard ratio [HR] with 95% confidence interval [CI 2.92 [1.1–7.75], p = 0.024). However, the CECL-DCNN predicted MVI was a significant prognostic factor for both OS (HR with 95% CI: 6.03 [1.7–21.39], p = 0.009) and RFS (HR with 95% CI: 3.3 [1.23–8.91], p = 0.011) in the test group.

Conclusions

The proposed CECL-DCNN model based on preoperative CEUS video can serve as a noninvasive tool to predict MVI status in HCC, thereby predicting poor prognosis.

Hepatocellular Carcinoma in Evolution: Correlation with CEUS LI-RADS

Hepatocellular carcinoma (HCC) is the most common primary malignancy of the liver with a high incidence worldwide and a high associated mortality. Well-recognized risk factors that cause a predisposition to the development of HCC include chronic infection with the hepatitis B or C virus, alcohol-related and non-alcohol-related fatty liver disease, and cirrhosis. In these chronically diseased livers, benign regenerative nodules can increase in size and develop cellular atypia that progress into dysplastic nodules and ultimately HCC. This sequence of hepatocarcinogenesis is coupled with changes in nodule vascularity, including progressive decreased density of portal triads and induced neoangiogenesis, resulting in increased hepatic arterial recruitment. Changes in vascularity result in an array of patterns of nodule enhancement and washout, which can be sensitively depicted with dynamic real-time contrast-enhanced US. Regenerative nodules are isoenhancing relative to the liver with all phases, while HCC classically shows avid arterial phase hyperenhancement with late mild washout. In between, there is great variation as nodules evolve through progressive grades of dysplasia toward HCC. Observed patterns of enhancement and washout can be used to diagnose or stratify the risk of malignancy in liver nodules by using the diagnostic algorithm described by the American College of Radiology Liver Imaging Reporting and Data System (LI-RADS). This facilitates the detection and close monitoring of potential early-stage disease. LI-RADS categorizes nodules according to a probabilistic likelihood for HCC with criteria for LR-5 nodules that are highly specific for the diagnosis of HCC, allowing treatment without exposing the patient to invasive biopsy. An invited commentary by Fetzer is available online. Online supplemental material and the slide presentation from the RSNA Annual Meeting are available for this article. ^©RSNA, 2022.

[Alternatives of histological material collection - When and how is histological confirmation by ultrasound (US), computer tomography (CT) or endosonography (EUS) useful?]

Histological classifications of tumorous lesions together with adequate staging are necessary for stage-appropriate and personalized therapies. The indications, technical possibilities, and limitations as well as potential complications of image-guided needle biopsy by ultrasound, computed tomography, and endosonography are described. Which procedure for which organ and which lesion?

Preoperative Survival Prediction in Intrahepatic Cholangiocarcinoma Using an Ultrasound-Based Radiographic-Radiomics Signature

OBJECTIVES

To construct a preoperative model for survival prediction in intrahepatic cholangiocarcinoma (ICC) patients using ultrasound (US) based radiographic-radiomics signatures.

METHODS

Between April 2010 and September 2015, 170 patients with ICC who underwent curative resection were retrospectively recruited. Overall survival (OS)-related radiographic signatures and radiomics signatures based on preoperative US were built and assessed through a time-dependent receiver operating characteristic curve analysis. A nomogram was developed based on the selected predictors from the radiographic-radiomics signatures and clinical and laboratory results of the training cohort (n = 127), validated in an independent testing cohort (n = 43) by the concordance index (C-index), and compared with the Tumor Node Metastasis (TNM) cancer staging system as well as the radiographic and radiomics nomograms.

RESULTS

The median areas under the curve of the radiomics signature and radiographic signature were higher than that of the TNM staging system in the testing cohort, although the values were not significantly different (0.76-0.82 versus 0.62, P = .485 and .264). The preoperative nomogram with CA 19-9, sex, ascites, radiomics signature, and radiographic signature had C-indexes of 0.72 and 0.75 in the training and testing cohorts, respectively, and it had significantly higher predictive performance than the 8th TNM staging system in the testing cohort (C-index: 0.75 versus 0.67, P = .004) and a higher C-index than the radiomics nomograms (0.75 versus 0.68, P = .044).

CONCLUSIONS

The preoperative nomogram integrated with the radiographic-radiomics signature demonstrated good predictive performance for OS in ICC and was superior to the 8th TNM staging system.

Interpretable Machine Learning for Characterization of Focal Liver Lesions by Contrast-Enhanced Ultrasound

This work proposes an interpretable radiomics approach to differentiate between malignant and benign focal liver lesions (FLLs) on contrast-enhanced ultrasound (CEUS). Although CEUS has shown promise for differential FLLs diagnosis, current clinical assessment is performed only by qualitative analysis of the contrast enhancement patterns. Quantitative analysis is often hampered by the unavoidable presence of motion artifacts and by the complex, spatiotemporal nature of liver contrast enhancement, consisting of multiple, overlapping vascular phases. To fully exploit the wealth of information in CEUS, while coping with these challenges, here we propose combining features extracted by the temporal and spatiotemporal analysis in the arterial phase enhancement with spatial features extracted by texture analysis at different time points. Using the extracted features as input, several machine learning classifiers are optimized to achieve semiautomatic FLLs characterization, for which there is no need for motion compensation and the only manual input required is the location of a suspicious lesion. Clinical validation on 87 FLLs from 72 patients at risk for hepatocellular carcinoma (HCC) showed promising performance, achieving a balanced accuracy of 0.84 in the distinction between benign and malignant lesions. Analysis of feature relevance demonstrates that a combination of spatiotemporal and texture features is needed to achieve the best performance. Interpretation of the most relevant features suggests that aspects related to microvascular perfusion and the microvascular architecture, together with the spatial enhancement characteristics at wash-in and peak enhancement, are important to aid the accurate characterization of FLLs.

MRI-Based Radiomics Models to Discriminate Hepatocellular Carcinoma and Non-Hepatocellular Carcinoma in LR-M According to LI-RADS Version 2018

Differentiating hepatocellular carcinoma (HCC) from other primary liver malignancies in the Liver Imaging Reporting and Data System (LI-RADS) M (LR-M) tumours noninvasively is critical for patient treatment options, but visual evaluation based on medical images is a very challenging task. This study aimed to evaluate whether magnetic resonance imaging (MRI) models based on radiomics features could further improve the ability to classify LR-M tumour subtypes. A total of 102 liver tumours were defined as LR-M by two radiologists based on LI-RADS and were confirmed to be HCC (n = 31) and non-HCC (n = 71) by surgery. A radiomics signature was constructed based on reproducible features using the max-relevance and min-redundancy (mRMR) and least absolute shrinkage and selection operator (LASSO) logistic regression algorithms with tenfold cross-validation. Logistic regression modelling was applied to establish different models based on T2-weighted imaging (T2WI), arterial phase (AP), portal vein phase (PVP), and combined models. These models were verified independently in the validation cohort. The area under the curve (AUC) of the models based on T2WI, AP, PVP, T2WI + AP, T2WI + PVP, AP + PVP, and T2WI + AP + PVP were 0.768, 0.838, 0.778, 0.880, 0.818, 0.832, and 0.884, respectively. The combined model based on T2WI + AP + PVP showed the best performance in the training cohort and validation cohort. The discrimination efficiency of each radiomics model was significantly better than that of junior radiologists’ visual assessment (p < 0.05; Delong). Therefore, the MRI-based radiomics models had a good ability to discriminate between HCC and non-HCC in LR-M tumours, providing more options to improve the accuracy of LI-RADS classification.

Risk Stratification and Distribution of Hepatocellular Carcinomas in CEUS and CT/MRI LI-RADS: A Meta-Analysis

Background

CEUS LI-RADS and CT/MRI LI-RADS have been used in clinical practice for several years. However, there is a lack of evidence-based study to compare the proportion of hepatocellular carcinomas (HCCs) in each category and the distribution of HCCs of these two categorization systems.

Purpose

The purpose of this study was to compare the proportion of HCCs between corresponding CEUS LI-RADS and CT/MRI LI-RADS categories and the distribution of HCCs and non-HCC malignancies in each category.

Methods

We searched PubMed, Embase, and Cochrane Central databases from January 2014 to December 2021. The proportion of HCCs and non-HCC malignancies and the corresponding sensitivity, specificity, accuracy, diagnostic odds ratio (DOR), and area under the curve (AUC) of the LR-5 and LR-M categories were determined using a random-effect model.

Results

A total of 43 studies were included. The proportion of HCCs in CEUS LR-5 was 96%, and that in CECT/MRI LR-5 was 95% (p > 0.05). The proportion of non-HCC malignancy in CEUS LR-M was lower than that of CT/MRI LR-M (35% vs. 58%, p = 0.01). The sensitivity, specificity, and accuracy of CEUS LR-5 for HCCs were 73%, 92%, and 78%, respectively, and of CT/MRI LR-5 for HCCs, 69%, 92%, and 76%, respectively.

Conclusion

With the upshift of the LI-RADS category, the proportion of HCCs increased. CEUS LR-3 has a lower risk of HCCs than CT/MRI LR-3. CEUS LR-5 and CT/MRI LR-5 have a similar diagnostic performance for HCCs. CEUS LR-M has a higher proportion of HCCs and a lower proportion of non-HCC malignancies compared with CT/MRI LR-M.

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

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

Contrast-enhanced US diagnostic algorithm of hepatocellular carcinoma in patients with occult hepatitis B

PURPOSE

To assess the diagnostic performance of contrast-enhanced (CE) US Liver Imaging Reporting and Data System (LI-RADS) version 2017 and propose a diagnostic algorithm in diagnosing hepatocellular carcinoma (HCC) in patients with occult HBV infection (OBI).

METHODS

251 OBI patients with 251 newly diagnosed focal liver lesions were retrospectively enrolled. Each nodule was evaluated according to CEUS LI-RADS. The subgroup analyses were also performed in patients with alpha-fetoprotein (AFP) more than 20ug/L or not. Diagnostic performance of CEUS LI-RADS for diagnosing HCC was validated via sensitivity, specificity, accuracy, positive predictive value (PPV), and negative predictive value (NPV), respectively.

RESULTS

There were 90 HCCs (90 of 251, 35.9%), of which 2 (2.0%), 53 (53.5%), and 35 (35.4%) were classified as LR-4, LR-5, and LR-M, respectively. The sensitivity, specificity, accuracy, PPV, and NPV of CEUS LR-5 for HCC diagnosis were 58.9%, 88.8%, 78.1%, 74.6%, and 79.4%, respectively. AFP increased in 50.6% (45/89) HCCs. Using a proposed diagnostic algorithm (for OBI patients with AFP more than 20 ug/L, LR-5 nodules were diagnosed as definitely HCC), the sensitivity, specificity, accuracy, PPV, and NPV were 62.2%, 71.4%, 63.5%, 93.3%, and 22.7%, respectively. Therefore, 12.2% (30 of 246) nodules could be confirmed as HCC by CEUS without biopsy.

CONCLUSION

HCC diagnosis in patients with OBI is challenging. However, using LR-5 as a noninvasively diagnostic standard in OBI patients with AFP more than 20ug/L, HCC could be confirmed by CEUS without biopsy.

Contrast-enhanced ultrasound Liver Imaging Reporting and Data System category M: a systematic review and meta-analysis

PURPOSE

A meta-analysis was conducted to determine the proportion of contrast-enhanced ultrasound (CEUS) Liver Imaging Reporting and Data System category M (LR-M) in hepatocellular carcinomas (HCCs) and non-HCC malignancies and to investigate the frequency of individual CEUS LR-M imaging features.

METHODS

The MEDLINE and Embase databases were searched from January 1, 2016 to July 23, 2020 for studies reporting the proportion of CEUS LR-M in HCC and non-HCC malignancies. The meta-analytic pooled proportions of HCC and non-HCC malignancies in the CEUS LR-M category were calculated. The meta-analytic frequencies of CEUS LR-M imaging features in nonHCC malignancies were also determined. Risk of bias and applicability were evaluated using the Quality Assessment of Diagnostic Accuracy Studies-2 tool.

RESULTS

Twelve studies reporting the diagnostic performance of the CEUS LR-M category were identified, as well as seven studies reporting the frequencies of individual CEUS LR-M imaging features. The pooled proportions of HCC and non-HCC malignancies in the CEUS LR-M category were 54% (95% confidence interval [CI], 44% to 65%) and 40% (95% CI, 28% to 53%), respectively. The pooled frequencies of individual CEUS LR-M imaging features in non-HCC malignancies were 30% (95% CI, 17% to 45%) for rim arterial phase hyperenhancement, 79% (95% CI, 66% to 90%) for early (<60 s) washout, and 42% (95% CI, 21% to 64%) for marked washout.

CONCLUSION

In total, 94% of CEUS LR-M lesions were malignancies, with HCCs representing 54% and non-HCC malignancies representing 40%. The frequencies of individual CEUS LR-M imaging features varied; early washout showed the highest frequency for non-HCC malignancies.

LR-M Observations on Contrast-Enhanced Ultrasound: Detection of Hepatocellular Carcinoma Using Additional Features in Comparison with Current LI-RADS Criteria

Background: Contrast-enhanced ultrasound (CEUS) LI-RADS assigns category LR-M for observations that are definitely or probably malignant but that are not specific on imaging for hepatocellular carcinoma (HCC). A high percentage of LR-M observations represent HCC. Objective: To retrospectively evaluate the utility of additional features, beyond conventional LI-RADS major features, for detecting HCC among LR-M observations on CEUS. Methods: This retrospective study included 174 patients (145 men, 29 women; mean age, 53 years) at high-risk for HCC who underwent CEUS from August 2014 to June 2016, demonstrating an LR-M observation using CEUS LI-RADS version 2017. Two radiologists independently assessed CEUS images for major features and four additional features (chaotic vessels, peripheral circular artery, clear boundary of the tumor enhancement, clear boundary of the intratumoral nonenhanced area). Diagnostic performance was assessed of four proposed criteria for the detection of HCC among LR-M observations. The impact on HCC detection of criteria based on the additional findings was further explored. Histology or composite imaging and clinical follow-up served as reference standard. Results: The 174 LR-M observations included 142 HCCs and 32 non-HCCs (20 intrahepatic cholangiocarcinomas, 5 combined hepatocellular-cholangiocarcinomas, 7 benign lesions). Interreader agreement of the additional features, expressed as kappa, ranged from 0.65 to 0.88. Two of the additional features exhibited PPV ≥95.0% for HCC: chaotic vessels (95.0%) and peripheral circular arteries (98.1%). The presence of either of these two additional features achieved sensitivity of 50.7%, specificity of 90.6%, PPV of 96.0%, and NPV of 29.3% for HCC. Three other explored criteria incorporating variations of major LI-RADS features, but not the additional features, had sensitivities of 55.6%-96.5%, specificities of 49.6%-68.8%, PPVs of 87.8%-90.6%, and NPVs of 25.0%-75.0%. Criteria using additional features recategorized 75 of 174 LR-M observations as LR-5, of which 72 were HCC. Conclusion: The presence of chaotic vessels and/or peripheral circular artery had high specificity and PPV for HCC among LR-M observations. Other explored criteria based on major features did not achieve higher specificity or PPV. Clinical Impact: Clinical adoption of the additional CEUS features could help establish the diagnosis of HCC noninvasively and avoid the need for biopsy of LR-M observations.

Impact of Revision of the LR-M Criteria on the Diagnostic Performance of Contrast-Enhanced Ultrasound LI-RADS

This study was aimed at revising the LI-RADS M category (LR-M) criteria to improve the diagnostic performance categories LR-5 and LR-M of the contrast-enhanced ultrasound (CEUS) Liver Imaging Reporting and Data System (LI-RADS) Version 2017. We enrolled 264 patients (264 nodules) with a risk for hepatocellular carcinoma (HCC). The nodules were assigned specific CEUS LI-RADS categories. Washout onset times for all nodules were noted. The diagnostic performance of LR-5 and LR-M was analyzed based on the different early washout criterion for the LR-M category. The positive predictive values in LR-5, LR-4 and LR-3 were 98.6%, 72.2% and 16.7%, respectively, and that for non-HCC malignancies in LR-M was 25.0%. Patients in the LR-M category were reclassified using 45 s as the early washout criterion. LR-5 had higher sensitivity (65.5% vs. 76.2%, p = 0.012) and area under the receiver operating characteristic curve (0.80 vs. 0.85, p = 0.001) for HCC diagnosis after reclassification. LR-M also had higher specificity (71.4% vs. 81.3%, p = 0.010) in diagnosing non-HCC malignancies after reclassification. Our findings suggest CEUS LR-5 is effective for HCC diagnosis. The use of 45 s as the time criterion of early washout for LR-M can improve LR-5 and LR-M performance in the diagnosis of HCC and non-HCC malignancies, respectively.

Role of Contrast-Enhanced Ultrasonography in Hepatocellular Carcinoma by Using LI-RADS and Ancillary Features: A Single Tertiary Centre Experience

Clinical utility of ancillary features (AFs) in contrast-enhanced ultrasound (CEUS) Liver Imaging Reporting and Data System (LI-RADS®) is yet to be established. In this study, we assessed the diagnostic yield of CEUS LI-RADS and AFs in hepatocellular carcinoma (HCC). We retrospectively included patients with risk factors for HCC and newly diagnosed focal liver lesions (FLL). All lesions have been categorized according to the CEUS LI-RADS v2017 by an experienced sonographer blinded to clinical data and to the final diagnosis. From a total of 143 patients with 191 FLL, AFs favoring HCC were observed in 19.8% cases as hypoechoic rim and in 16.7% cases as nodule-in nodule architecture. From the total of 141 HCC cases, 83.6% were correctly classified: 57.4%- LR-5 and 26.2%- LR-4. In 9.21% cases, CEUS indicated LR-M; 2.12% cases- LR-3. The LR-5 category was 96.2% predictive (PPV) of HCC. LR-5 had 60.4% sensitivity and 93.6% specificity. PPV for primitive malignancy (LR-4 + LR-5) was 95.7%, with 88% sensitivity, 89.3% specificity and 88.4% accuracy for HCC. LR-4 category had 94.8% PPV and 26.2% sensitivity. CEUS LR4 + LR5 had 81,8% sensitivity for HCCs over 2 cm and 78.57% sensitivity for smaller HCCs. CEUS LR-5 remains an excellent diagnostic tool for HCC, despite the size of the lesion. The use of AFs might improve the overarching goal of LR-5 + LR-4 diagnosis of high specificity for HCC and exclusion of non-HCC malignancy.

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.

Using new criteria to improve the differentiation between HCC and non-HCC malignancies: clinical practice and discussion in CEUS LI-RADS 2017

PURPOSE

Using contrast-enhanced ultrasound (CEUS) to evaluate the diagnostic performance of liver imaging reporting and data system (LI-RADS) version 2017 and to explore potential ways to improve the efficacy.

METHODS

A total of 315 nodules were classified as LR-1 to LR-5, LR-M, and LR-TIV. New criteria were applied by adjusting the early washout onset (< 45 s) and the time of marked washout (within 3 min). Two subgroups of the LR-M nodules were recategorized as LR-5, respectively. The diagnostic performance was evaluated by calculating the accuracy, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV).

RESULTS

By adjusting early washout onset to < 45 s, the LR-5 as a standard for diagnosing HCC had an improved sensitivity (74.1% vs. 56.1%, P < 0.001) without significant change in PPV (93.3% vs. 96.1%, P = 0.267), but the specificity was decreased (48.3% vs. 78.5%, P = 0.018). The LR-M as a standard for the diagnosis of non-HCC malignancies had an increase in specificity (89.2% vs. 66.2%, P < 0.001) but a decrease in sensitivity (31.5% vs. 68.4%, P = 0.023). After reclassification according to the time of marked washout, the sensitivity of the LR-5 increased (80% vs. 56.1%, P < 0.001) without a change in PPV (94.9% vs. 96.1%, P = 0.626) and specificity (80% vs. 78.5%, P = 0.879). For reclassified LR-M nodules, the specificity increased (87.5% versus 66.2%, P < 0.001) with a non-significant decrease in sensitivity (47.3% vs. 68.4%, P = 0.189).

CONCLUSIONS

The CEUS LI-RADS showed good confidence in diagnosing HCC while tended to misdiagnose HCC as non-HCC malignancies. Adjusting the marked washout time within 3 min would reduce the possibility of this misdiagnosis.

New frontiers in liver ultrasound: From mono to multi parametricity

Modern liver ultrasonography (US) has become a "one-stop shop" able to provide not only anatomic and morphologic but also functional information about vascularity, stiffness and other various liver tissue properties. Modern US techniques allow a quantitative assessment of various liver diseases. US scanning is no more limited to the visualized plane, but three-dimensional, volumetric acquisition and consequent post-processing are also possible. Further, US scan can be consistently merged and visualized in real time with Computed Tomography and Magnetic Resonance Imaging examinations. Effective and safe microbubble-based contrast agents allow a real time, dynamic study of contrast kinetic for the detection and characterization of focal liver lesions. Ultrasound can be used to guide loco-regional treatment of liver malignancies and to assess tumoral response either to interventional procedures or medical therapies. Microbubbles may also carry and deliver drugs under ultrasound exposure. US plays a crucial role in diagnosing, treating and monitoring focal and diffuse liver disease. On the basis of personal experience and literature data, this paper is aimed to review the main topics involving recent advances in the field of liver ultrasound.

The Value of Contrast-Enhanced Ultrasound Liver Imaging Reporting and Data System in the Diagnosis of Hepatocellular Carcinoma:: A Meta-Analysis

OBJECTIVES

The aim of this study is to systematically evaluate the diagnostic ability of the contrast-enhanced ultrasound (CEUS) liver imaging reporting and data system (LI-RADS) in hepatocellular carcinoma (HCC).

METHODS

We searched relevant studies from PubMed, Medline, and Embase database. After literature search, duplicate removal, and data extraction, we calculated and analyzed the pooled sensitivity, pooled specificity, pooled odds ratios of diagnostic, pooled likelihood ratio (LR) of positive and negative, and area under the curve (AUC), accuracy, and F1 score to evaluate the diagnostic value of CEUS LI-RADS for HCC.

RESULTS

Thirteen studies and 6491 patients were included in this analysis. The pooled sensitivity and pooled specificity were 0.72 (95% confidence interval [CI], 0.70-0.73) and 0.92 (95% CI, 0.91-0.93), respectively. The positive LR was 8.02 (95% CI, 4.93-13.06) and the negative LR was 0.31 (95% CI, 0.27-0.37). The pooled diagnostic odds ratio was 27.91 (95% CI, 15.39-50.63). The overall AUC was 0.8406 and the accuracy was 0.77.

CONCLUSIONS

CEUS LI-RADS is an effective and promising method to diagnose HCC.

Inter-reader reliability of contrast-enhanced ultrasound Liver Imaging Reporting and Data System: a meta-analysis

PURPOSE

To systematically determine the inter-reader reliability of the contrast-enhanced ultrasound (CEUS) Liver Imaging Reporting and Data System (LI-RADS), with emphasis on its major features for hepatocellular carcinoma (HCC) and LR-M (LI-RADS category M) features for non-HCC malignancy.

METHODS

MEDLINE, EMBASE, and Cochrane databases were searched from January 2016 to March 2021 to identify original articles reporting the inter-reader reliability of CEUS LI-RADS. Meta-analytic pooled kappa values (κ) were calculated for major features [nonrim arterial-phase hyperenhancement (APHE), mild and late washout], LR-M features (rim APHE, early washout), and LI-RADS categorization using the DerSimonian-Laird random-effects model. Meta-regression analysis was performed to explore any causes of study heterogeneity.

RESULTS

Twelve studies with a total of 2862 lesions were included. The meta-analytic pooled κ of nonrim APHE, mild and late washout, rim APHE, early washout, and LI-RADS categorization were 0.73 [95% confidence interval (CI), 0.67 - 0.79], 0.69 (95% CI, 0.54-0.84), 0.54 (95% CI, 0.37-0.71), 0.62 (95% CI, 0.45-0.79), and 0.75 (95% CI, 0.64-0.87), respectively. Compared with the major features, LR-M features had a lower meta-analytic pooled κ. Substantial study heterogeneity was noted in the LI-RADS categorization, and lesion size (p = 0.03) and the homogeneity in reader experience (p = 0.03) were significantly associated with study heterogeneity.

CONCLUSIONS

CEUS LI-RADS showed substantial inter-reader reliability for major features and LI-RADS categorization, but relatively lower reliability was found for LR-M features. In our opinion, the definitions of imaging features require further refinement to improve the inter-reader reliability of CEUS LI-RADS.

Contrast-Enhanced Ultrasound: A Useful Tool to Study and Monitor Hepatic Tumors Treated With Histotripsy

Histotripsy is a novel noninvasive nonthermal, nonionizing, and precise treatment technique for tissue destruction. Contrast-enhanced ultrasound (CEUS) improves the detection, characterization, and follow-up of hepatic lesions because it depicts accurately the vascular perfusion of both normal hepatic tissue and hepatic tumors. We present the spectrum of imaging findings of CEUS after histotripsy treatment of hepatic tumors. CEUS provides real-time information, a close approximation to the dimension of the lesion, and a clear definition of its margins. Hepatic tumors detected by ultrasound can be potentially treated using B-mode ultrasound-guided histotripsy and characterized and monitored with CEUS. CEUS has shown to be very useful after tissue treatment to monitor and assess the evolution of the treated zone. Histotripsy treated zones are practically isoechogenic and slightly heterogeneous, and their limits are difficult to establish using standard B-mode ultrasound. The use of CEUS after histotripsy showing uptake of contrast protruding into the treated zone is clinically relevant to identify residual tumors and establish the most appropriate management strategy avoiding unnecessary treatments. We here describe CEUS findings after histotripsy for hepatic tumors.

Imaging After Locoregional Therapy for Hepatocellular Carcinoma With Emphasis on LIRADS Treatment Response Assessment Criteria

The Liver Imaging Reporting and Data System (LI-RADS) is a set of algorithms designed to provide a standardized, comprehensive framework for the interpretation of surveillance and diagnostic imaging in patients at high risk for hepatocellular carcinoma. LI-RADS is the result of a multidisciplinary collaboration between radiologists, hepatologists, hepatobiliary surgeons and pathologists and has recently been incorporated into the practice guidelines for the American Association for the Study of Liver Diseases (AASLD) and made congruent with the Organ Procurement and Transplantation Network (OPTN) criteria. This manuscript illustrates the common ultrasound, computed tomography, and magnetic resonance imaging appearances of hepatocellular carcinoma and describes how these findings can be properly categorized using the LI-RADS system.

What factors predict physicians' utilization behavior of contrast-enhanced ultrasound? Evidence from the integration of the Theory of Planned Behavior and Technology Acceptance Model using a structural equation modeling approach

BACKGROUND

The promotion of early diagnosis is undoubtedly effective in reducing the burden of disease. Contrast-enhanced ultrasound (CEUS) is a diagnostic technology for liver cancer, but its implementation faces some challenges. Understanding the influencing factors of CEUS utilization is crucial for its successful implementation. However, such research is rare. The aims of this study were to investigate the status of CEUS utilization and its predictors in China.

METHODS

Through multistage random sampling, a cross-sectional study design was conducted among physicians in charge of direct use of CEUS working at liver disease-related departments of sampled health institutions. To access the potential influencing factors of physicians' CEUS utilization, a structured questionnaire was developed based on the theoretical model, which was developed by integration of the Theory of Planned Behavior (TPB) and Technology Acceptance Model (TAM). Structural equation modeling was used to verify the proposed hypotheses, and analyze the relationship and mechanism between the factors.

RESULTS

A total of 309 physicians were enrolled. The mean score of utilization behavior was 2.04 (SD = 1.07), and 37.22% above the mean. The favorable fitting results demonstrated that the integration of TAM and TPB was an acceptable model. SEM results also identified physicians' intentions to use CEUS was directly associated with utilization behavior (β = 0.287, P < 0.001). Attitude (β = 0.272, P < 0.001), subjective norm (β = 0.172, P = 0.013), perceived behavioral control (β = 0.491, P < 0.001) and perceived usefulness (β = 0.108, P = 0.027) significantly influenced physicians' intentions. Besides, subjective norm (β = 0.065, P = 0.021), perceived behavioral control (β = 0.141, P = 0.003), and perceived ease of use (β = 0.022, P = 0.033) indirectly affected physicians' CEUS utilization.

CONCLUSIONS

The findings provide a reference for understanding the factors associated with physicians' utilization of CEUS. Additionally, the proposed measures such as building innovative and incentive environment, providing high quality and adequate training, etc., will help promote the utilization of CEUS, thereby increasing the detection rate of liver cancer, and improving the survival rate and the quality of life for liver cancer patients.

CT/MRI LI-RADS v2018 vs. CEUS LI-RADS v2017-Can Things Be Put Together?

Different LI-RADS core documents were released for CEUS and for CT/MRI. Both documents rely on major and ancillary diagnostic criteria. The present paper offers an exhaustive comparison of the two documents focusing on the similarities, but especially on the differences, complementarity, and added value of imaging techniques in classifying liver nodules in cirrhotic livers. The major diagnostic criteria are defined, and the sensitivity and specificity of each major diagnostic criteria are presented according to the literature. The existing differences between techniques in assessing the major diagnostic features can be then exploited in order to ensure a better classification and a better clinical management of liver nodules in cirrhotic livers. Ancillary features depend on the imaging technique used, and their presence can upgrade or downgrade the LI-RADS score of an observation, but only as far as LI-RADS 4. MRI is the imaging technique that provides the greatest number of ancillary features, whereas CEUS has fewer ancillary features than other imaging techniques. In the final part of the manuscript, some recommendations are made by the authors in order to guidephysicians as to when adding another imaging technique can be helpful in managing liver nodules in cirrhotic livers.

MR versus CEUS LI-RADS for Distinguishing Hepatocellular Carcinoma from other Hepatic Malignancies in High-Risk Patients

Distinguishing between other hepatic malignancies (OMs) and hepatocellular carcinoma (HCC) is vital to allow clinicians to determine optimal treatment and assess prognosis in patients at high risk for HCC. This study evaluated the performance of the Liver Imaging Reporting and Data System (LI-RADS) using magnetic resonance imaging (MRI) versus contrast-enhanced ultrasonography (CEUS) for differentiating HCC from OMs in patients at high risk for HCC. This retrospective study consecutively enrolled 106 high-risk patients with HCC and 52 high-risk patients with OMs. Patients underwent both MRI and CEUS, with histologic diagnosis as a reference standard. The diagnostic performance of MR versus CEUS LI-RADS was calculated and compared. The performance of the modified CEUS LI-RADS criteria was also evaluated and compared. Our research found that MRI features significantly differed between patients with OMs and those with HCC (p < 0.05), with sensitivities of 34.6%-69.2% and specificities of 83.0%-95.3% for diagnosing OMs and an LI-RADS M (LR-M): definite or probable malignancy, not specific for hepatocellular carcinoma sensitivity of 90.4% and specificity of 83.0% for diagnosing OM. CEUS features also significantly differed between patients with OM and HCC (p < 0.05), with sensitivities of 11.5%-96.2% and specificities of 23.6%-100% for diagnosing OMs, and an LR-M sensitivity of 98.1% and specificity of 84.0% for diagnosing OMs. Accuracies of category LR-M did not significantly differ between MR and CEUS LI-RADS (85.4% vs. 88.6%, p = 0.724). After reclassification of category LR-M nodules to category LR-5 if they exhibited clear intratumoral non-enhanced area boundaries and no punched-out appearance before 5 min, accuracy increased from 88.6% to 96.8% for CEUS LR-M and from 84.8% to 91.1% for CEUS LR-5. LR-M accuracies were significantly higher for the modified version of the CEUS LI-RADS than for MR LI-RADS (96.8% vs. 85.4%, respectively, p = 0.04). CEUS LI-RADS and MR LI-RADS can effectively be used to distinguish HCC from OMs. In patients at high risk of HCC, performance may be further improved by using a modified CEUS LI-RADS classification system in which category LR-M lesions are considered LR-5 if they have clear intratumoral non-enhanced area boundaries and do not have a punched-out appearance.

Contrast-enhanced US for the Interventional Radiologist: Current and Emerging Applications

US is a powerful and nearly ubiquitous tool in the practice of interventional radiology. Use of contrast-enhanced US (CEUS) has gained traction in diagnostic imaging given the recent approval by the U.S. Food and Drug Administration (FDA) of microbubble contrast agents for use in the liver, such as sulfur hexafluoride lipid-type A microspheres. Adoption of CEUS by interventional radiologists can enhance not only procedure guidance but also preprocedure patient evaluation and assessment of treatment response across a wide spectrum of oncologic, vascular, and nonvascular procedures. In addition, the unique physical properties of microbubble contrast agents make them amenable as therapeutic vehicles in themselves, which can lay a foundation for future therapeutic innovations in the field in drug delivery, thrombolysis, and vascular flow augmentation. The purpose of this article is to provide an introduction to and overview of CEUS aimed at the interventional radiologist, highlighting its role before, during, and after frequently practiced oncologic and vascular interventions such as biopsy, ablation, transarterial chemoembolization, detection and control of hemorrhage, evaluation of transjugular intrahepatic portosystemic shunts (TIPS), detection of aortic endograft endoleak, thrombus detection and evaluation, evaluation of vascular malformations, lymphangiography, and percutaneous drain placement. Basic physical principles of CEUS, injection and scanning protocols, and logistics for practice implementation are also discussed. Early adoption of CEUS by the interventional radiology community will ensure rapid innovation of the field and development of future novel procedures. Online supplemental material is available for this article. ^©RSNA, 2020.

Imaging findings of fibrolamellar hepatocellular carcinomas on ultrasonography: A comparison with conventional hepatocellular carcinomas

BACKGROUND

Fibrolamellar hepatocellular carcinoma (FLHCC) is an unusual variant of hepatocellular carcinoma (HCC). Revealing the imaging features is important to the diagnosis of FLHCC.

OBJECTIVE

The aim of this study was to investigate the imaging characteristics of FLHCCs.

METHODS

This retrospective study included 29 patients with histopathologically proved FLHCC and 96 patients proved HCC. All patients underwent an ultrasound examination pre-operation.

RESULTS

The average maximum diameters of the FLHCC and HCC lesions were 7.4±4.1 cm and 4.1±3.0 cm, respectively. On the ultrasound, 79.3% of the FLHCCs and 12.3% of the HCCs showed the internal hyperechoic area; 48.3% of the FLHCCs and 3.3% of the HCCs displayed a strip-like attenuation. Calcification was noted in 20.7% of the FLHCCs, while none in HCCs. On the contrast-enhanced ultrasound (CEUS), all FLHCC lesions and 87.7% of the HCCs displayed hyperenhancement in the arterial phase. An internal, unenhanced central scar appeared in all FLHCCs, while none in HCCs.

CONCLUSIONS

The ultrasonographic features of FLHCC lesions indicate that they are relatively large masses showing the internal hyperechoic area or strip-like attenuation or calcification on the US and hypervascularity with an unenhanced central scar on the CEUS as compared with conventional HCC lesions.

Contrast-enhanced ultrasound in the diagnosis of infiltrative hepatocellular carcinoma: A report of three cases

Infiltrative hepatocellular carcinoma (HCC) is a challenging imaging diagnosis due to its ill-defined appearance and variable enhancement, which may be difficult to distinguish from background changes from cirrhosis. The literature on the role of contrast-enhanced ultrasound (CEUS) in the diagnosis of infiltrative HCC is currently limited. CEUS has greater sensitivity for contrast enhancement due to its temporal resolution, and can be used when there is contraindication to CT or MRI contrast. We present 3 cases where CEUS aided in the diagnosis of infiltrative HCC in patients with equivocal CT and MRI findings and/or renal failure, with significant implications for management. As current guidelines focus on the role of CEUS in characterizing defined focal liver lesions or discrete observations on precontrast US, further studies are warranted to validate the utility of CEUS in the noninvasive diagnosis of infiltrative HCC and delineate its role in algorithms for imaging workup.

Performance of Ultrasound Techniques and the Potential of Artificial Intelligence in the Evaluation of Hepatocellular Carcinoma and Non-Alcoholic Fatty Liver Disease

Global statistics show an increasing percentage of patients that develop non-alcoholic fatty liver disease (NAFLD) and NAFLD-related hepatocellular carcinoma (HCC), even in the absence of cirrhosis. In the present review, we analyzed the diagnostic performance of ultrasonography (US) in the non-invasive evaluation of NAFLD and NAFLD-related HCC, as well as possibilities of optimizing US diagnosis with the help of artificial intelligence (AI) assistance. To date, US is the first-line examination recommended in the screening of patients with clinical suspicion of NAFLD, as it is readily available and leads to a better disease-specific surveillance. However, the conventional US presents limitations that significantly hamper its applicability in quantifying NAFLD and accurately characterizing a given focal liver lesion (FLL). Ultrasound contrast agents (UCAs) are an essential add-on to the conventional B-mode US and to the Doppler US that further empower this method, allowing the evaluation of the enhancement properties and the vascular architecture of FLLs, in comparison to the background parenchyma. The current paper also explores the new universe of AI and the various implications of deep learning algorithms in the evaluation of NAFLD and NAFLD-related HCC through US methods, concluding that it could potentially be a game changer for patient care.

An overview of hepatocellular carcinoma with atypical enhancement pattern: spectrum of magnetic resonance imaging findings with pathologic correlation

BACKGROUND

In the setting of cirrhotic liver, the diagnosis of hepatocellular carcinoma (HCC) is straightforward when typical imaging findings consisting of arterial hypervascularity followed by portal-venous washout are present in nodules larger than 1 cm. However, due to the complexity of hepatocarcinogenesis, not all HCCs present with typical vascular behaviour. Atypical forms such as hypervascular HCC without washout, isovascular or even hypovascular HCC can pose diagnostic dilemmas. In such cases, it is important to consider also the appearance of the nodules on diffusion-weighted imaging and hepatobiliary phase. In this regard, diffusion restriction and hypointensity on hepatobiliary phase are suggestive of malignancy. If both findings are present in hypervascular lesion without washout, or even in iso- or hypovascular lesion in cirrhotic liver, HCC should be considered. Moreover, other ancillary imaging findings such as the presence of the capsule, fat content, signal intensity on T2-weighted image favour the diagnosis of HCC. Another form of atypical HCCs are lesions which show hyperintensity on hepatobiliary phase. Therefore, the aim of the present study was to provide an overview of HCCs with atypical enhancement pattern, and focus on their magnetic resonance imaging (MRI) features.

CONCLUSIONS

In order to correctly characterize atypical HCC lesions in cirrhotic liver it is important to consider not only vascular behaviour of the nodule, but also ancillary MRI features, such as diffusion restriction, hepatobiliary phase hypointensity, and T2-weighted hyperintensity. Fat content, corona enhancement, mosaic architecture are other MRI feautures which favour the diagnosis of HCC even in the absence of typical vascular profile.

Effects of Contrast-Enhanced Ultrasound of Indeterminate Renal Masses on Patient Clinical Management: Retrospective Analysis From 2 Institutions

OBJECTIVES

To investigate the long-term impact of contrast-enhanced ultrasound (CEUS) on the treatment of patients with indeterminate renal masses.

METHODS

In this retrospective study, consecutive charts of all patients receiving renal CEUS at 1 of 2 academic medical centers between January 1, 2014, and December 31, 2018, were reviewed. Patients were included in the study if they had documented chronic renal disease (estimated glomerular filtration rate < 60 mL/min/1.73 m² ) or prior nephrectomy and received CEUS for a previously untreated renal mass.

RESULTS

A total of 215 lesions in 157 patients were used for analysis. Contrast-enhanced ultrasound provided a final treatment recommendation in 71.6% of lesions (154 of 215). Of these 154 lesions, 7.8% (12 of 154) were lost to follow-up despite CEUS suggesting malignancy; 15.6% (24 of 154) went directly for surgical intervention, with malignancy confirmed by pathologic results in 87.5% (21 of 24) of these cases; and the remaining 76.6% (118 of 154) were deemed benign and required no additional follow-up. Of the 118 lesions diagnosed by CEUS as benign and requiring no follow-up, none showed evidence of later renal cell carcinoma development and, only 5.1% (6 of 118) of the total population was referred for further cross-sectional imaging of the mass in question. In 28.4% of all lesions (61 of 215), CEUS resulted in a recommendation for surveillance imaging at a 6- to 12-month interval, and less than 10% (6 of 61) of these underwent additional cross-sectional imaging within the recommended 6 months after CEUS.

CONCLUSIONS

These findings highlight the impact of CEUS on clinical treatment of indeterminate renal masses, including reducing the use of the potentially nephrotoxic contrast agents and providing a direct pathway to transplant.

Contrast-enhanced ultrasound of benign and malignant liver lesions in children

Contrast-enhanced ultrasound (CEUS) is increasingly being used in children. One of the most common referrals for CEUS performance is characterization of indeterminate focal liver lesions and follow-up of known liver lesions. In this setting, CEUS is performed with intravenous administration of ultrasound contrast agents (UCAs). When injected into a vein, UCA microbubbles remain confined within the vascular network until they dissipate. Therefore, visualization of UCA within the tissues and lesions corresponds to true blood flow. CEUS enables continuous, real-time observation of the enhancement pattern of a focal liver lesion, allowing in most cases for a definite diagnosis and obviating the need for further cross-sectional imaging or other interventional procedures. The recent approval of Lumason (Bracco Diagnostics, Monroe Township, NJ) for pediatric liver CEUS applications has spurred the widespread use of CEUS. In this review article we describe the role of CEUS in pediatric liver applications, focusing on the examination technique and interpretation of main imaging findings of the most commonly encountered benign and malignant focal liver lesions. We also compare the diagnostic performance of CEUS with other imaging modalities for accurate characterization of focal liver lesions.

LI-RADS and transplantation: challenges and controversies

Patients with early stage hepatocellular carcinoma (HCC) can be cured by liver transplantation. HCC imaging features on CT or MRI are specific enough to allow for definitive diagnosis and treatment without the need of confirmatory biopsy. When applied to the appropriate at-risk population the Liver Imaging Reporting and Data System (LI-RADS) imaging criteria achieve high specificity and positive predictive value for the diagnosis of HCC. The Organ Procurement and Transplantation Network (OPTN) is the United States organization that aims to assure the adequate and fair distribution of livers across candidates. Given the importance of fair organ allocation, OPTN also provides stringent imaging criteria for the diagnosis of HCC aiming to avoid false positive diagnosis. Although most imaging criteria are identical for both systems, discrepancies between LI-RADS and the current OPTN classification system for HCC diagnosis exists. Main differences include, but are not limited to, the binary approach of OPTN to classify lesions as HCC or not, versus the probabilistic algorithmic approach of LI-RADS, technical and interpretation considerations, and the approach towards treated lesions. The purpose of this article is to highlight the similarities and discrepancies between LI-RADS and the current OPTN criteria for HCC diagnosis and the implications that these differences may have on the management of patients who are transplant candidates.

Diagnostic performance of intravascular perfusion based contrast-enhanced ultrasound LI-RADS in the evaluation of hepatocellular carcinoma

BACKGROUND

The contrast-enhanced ultrasound (CEUS) liver imaging reporting and data system (LI-RADS) is a relative new algorithm for hepatocellular carcinoma (HCC) assessment.

OBJECTIVE

To validate the diagnostic efficiency of the intravascular perfusion based CEUS LI-RADS for HCC.

METHODS

Archives of 873 patients with focal liver lesions (FLLs) undergoing CEUS were reviewed, and target images were read by two sonologists independently according to the CEUS LI-RADS. The diagnostic performance was calculated and compared.

RESULTS

Assessment with reference to CEUS LI-RADS, 87 of 218 FLLs (39.9%) were categorized as LR-5, 131 of 218 FLLs (60.1%) were categorized as non-LR-5, 19 of 99 HCCs were categorized as non-LR-5, and 7 of 119 non-HCCs were categorized as LR-5. The sensitivity, specificity, AUROC, positive and negative predictive values of CEUS LI-RADS for diagnosing HCC were 80.81%(95%CI: 71.7%-88.0%), 94.1%(95%CI: 88.3%-97.6%), 0.87 (95%CI: 0.82-0.92), 91.9%(95%CI: 84.1%-96.7%), and 85.5%(95%CI: 78.3%-91.0%), respectively.

CONCLUSIONS

The diagnostic efficiency of the intravascular perfusion based CEUS LI-RADS for the evaluation of HCCs is very good.

US-triggered Microbubble Destruction for Augmenting Hepatocellular Carcinoma Response to Transarterial Radioembolization: A Randomized Pilot Clinical Trial

Background US contrast agents are gas-filled microbubbles (MBs) that can be locally destroyed by using external US. Among other bioeffects, US-triggered MB destruction, also known as UTMD, has been shown to sensitize solid tumors to radiation in preclinical models through localized insult to the vascular endothelial cells. Purpose To evaluate the safety and preliminary efficacy of combining US-triggered MB destruction and transarterial radioembolization (TARE) in participants with hepatocellular carcinoma (HCC). Materials and Methods In this pilot clinical trial, participants with HCC scheduled for sublobar TARE were randomized to undergo either TARE or TARE with US-triggered MB destruction 1-4 hours and approximately 1 and 2 weeks after TARE. Enrollment took place between July 2017 and February 2020. Safety of US-triggered MB destruction was evaluated by physiologic monitoring, changes in liver function tests, adverse events, and radiopharmaceutical distribution. Treatment efficacy was evaluated by using modified Response Evaluation Criteria in Solid Tumors (mRECIST) on cross-sectional images, time to required next treatment, transplant rates, and overall survival. Differences across mRECIST reads were compared by using a Mann-Whitney U test, and the difference in prevalence of tumor response was evaluated by Fisher exact test, whereas differences in time to required next treatment and overall survival curves were compared by using a log-rank (Mantel-Cox) test. Results Safety results from 28 participants (mean age, 70 years ± 10 [standard deviation]; 17 men) demonstrated no significant changes in temperature (P = .31), heart rate (P = .92), diastolic pressure (P = .31), or systolic pressure (P = .06) before and after US-triggered MB destruction. No changes in liver function tests between treatment arms were observed 1 month after TARE (P > .15). Preliminary efficacy results showed a greater prevalence of tumor response (14 of 15 [93%; 95% CI: 68, 100] vs five of 10 [50%; 95% CI: 19, 81]; P = .02) in participants who underwent both US-triggered MB destruction and TARE (P = .02). Conclusion The combination of US-triggered microbubble destruction and transarterial radioembolization is feasible with an excellent safety profile in this patient population and appears to result in improved hepatocellular carcinoma treatment response. © RSNA, 2020.