Indeterminate focal liver lesions incidentally discovered at gray-scale US: role of contrast-enhanced sonography

Combination of HIFU with sulfur hexafluoride microbubbles in the treatment of solitary uterine fibroids: a systematic review and meta-analysis

OBJECTIVES

To assess the efficacy and safety of sulfur hexafluoride microbubbles on ultrasound-guided high-intensity focused ultrasound (HIFU) ablation of uterine fibroids.

METHODS

Studies that compared HIFU-microbubble combination with HIFU-only in patients with uterine fibroids were searched from inception to April 2022. The standardized mean difference (SMD) or relative risk (RR) with 95% confidence interval (CI) for different outcome parameters was calculated.

RESULTS

Seven studies were included, with a total of 901 patients (519 in the combination group and 382 in the HIFU-only group). The energy consumption for treating 1 cm3 of the lesion in the combination group was less than that in the HIFU-only group [SMD =  - 2.19, 95%CI (- 3.81, - 0.57), p = 0.008]. The use of microbubbles was associated with shortening the duration of the treatment and sonication [SMD =  - 2.60, 95%CI (- 4.09, - 1.10), p = 0.0007; SMD =  - 2.11, 95%CI (- 3.30, - 0.92), p = 0.0005]. The rates of significant greyscale changes during HIFU were greater in the combination group, as well as the increase of non-perfused volume ratio [RR = 1.26, 95%CI (1.04, 1.54), p = 0.02; SMD = 0.32, 95%CI (0.03, 0.61), p = 0.03]. The average sonication durations to reach significant greyscale changes and for ablating 1 cm3 of the fibroid lesion were shorter in the combination group [SMD =  - 1.24, 95%CI (- 2.02, - 0.45), p = 0.002; SMD =  - 0.22, 95%CI (- 0.42, - 0.02), p = 0.03]. The two groups had similar post-HIFU adverse effects, while the combination group had fewer intraprocedural adverse events like abdominal pain, sacrum pain, and leg pain.

CONCLUSIONS

Sulfur hexafluoride microbubbles can be safely used to enhance and accelerate the ablation effects of HIFU in the treatment of uterine fibroids.

CLINICAL RELEVANCE STATEMENT

The combination of HIFU with sulfur hexafluoride microbubbles offers a promising non-invasive treatment option for patients with uterine fibroids.

KEY POINTS

• Sulfur hexafluoride microbubbles combined with ultrasound-guided high-intensity focused ultrasound (USgHIFU) has potential advantages in the treatment of uterine fibroids. • Sulfur hexafluoride microbubbles not only enhance the effects of USgHIFU treatment for uterine fibroids but also shorten its duration. • Sulfur hexafluoride microbubbles do not increase the incidence of USgHIFU-related adverse events in the treatment of uterine fibroids.

Utility of the pediatric liver contrast-enhanced ultrasound criteria in differentiating malignant and benign multifocal lesions

BACKGROUND

The pediatric liver contrast-enhanced ultrasound (CEUS) criteria were developed to improve the diagnostic performance of CEUS in differentiating pediatric benign and malignant liver lesions. However, the diagnostic performance of CEUS in the evaluation of multiple focal liver lesions in the pediatric population has not yet been fully evaluated.

OBJECTIVE

To evaluate the diagnostic performance of the pediatric liver CEUS criteria in differentiating benign and malignant multifocal liver lesions in children.

MATERIALS AND METHODS

From April 2017 to September 2022, the CEUS characteristics of multifocal liver lesions in patients < 18 years were analyzed. Lesions classified as CEUS-1, CEUS-2 or CEUS-3 were considered benign and lesions classified as CEUS-4 or CEUS-5 were considered malignant. The diagnostic performance of the pediatric liver CEUS criteria (i.e. sensitivity, specificity, positive predictive value [PPV], negative predictive value [NPV] and accuracy) was assessed.

RESULTS

After exclusion, 21 patients (median age, 36.0 months; range, 1.0-204 months; 7 boys) were included. There were significant differences in the serum alpha fetoprotein level (P= 0.039) and the presence of washout (P < 0.001) between children with malignant and benign lesions. The sensitivity, specificity, PPV, NPV and accuracy of the pediatric liver CEUS criteria were 100.0% (10/10), 90.9% (10/11), 90.9% (10/11), 100.0% (10/10) and 95.2% (20/21), respectively.

CONCLUSION

The pediatric liver CEUS criteria had excellent diagnostic performance in differentiating benign and malignant multifocal liver lesions in children.

Assessing the impact and resource implications of contrast-enhanced ultrasound on workflow of patients with incidental focal liver lesions on the UK national health service

Background

Focal liver lesions (FLL) are abnormal growths that require timely identification. Contrast-enhanced ultrasound (CEUS) is a cost-effective imaging modality for characterising FLL with similar sensitivity to computed tomography (CT) and magnetic resonance imaging (MRI). Despite being recommended by NICE, its adoption within the national health service (NHS) is limited due to low clinical demand, limited referral, and lack of knowledge.

Purpose

To evaluate the impact of CEUS on patients with incidental FLL and assess the resource implications of introducing CEUS as a diagnostic service within the NHS.

Material and methods

A patient flow review and cost-minimisation analysis were conducted. This involved a targeted literature review, NHS Trust stakeholder consultations, and development of a Microsoft Excel cost-minimisation model to explore potential value of CEUS use versus CT and MRI by episode. A scenario analysis of the base-case explored increasing CEUS use to 50% and 90%. A sensitivity analysis was performed to assess how changes in assumptions impacted the model and the resulting cost estimates.

Results

The model, comparing a world with and without CEUS, showed that current use (base-case: 5%) resulted in cost savings of £224,790/year. The sensitivity analysis indicated that regardless of changes to the assumptions, CEUS still resulted in cost savings to the NHS. By increasing CEUS use to 50% and 90%, cost savings of up to £2,247,894/year and £4,046,208/year could be achieved, respectively.

Conclusion

By standardising CEUS use for characterising FLL, substantial cost savings could be realised, whilst reducing wait times and expanding diagnostic capacity, thus preserving limited CT and MRI capacity for high-priority cases.

Hydralazine-augmented contrast ultrasound imaging improves the detection of hepatocellular carcinoma

BACKGROUND

Hepatocellular carcinoma (HCC) detection with B-mode and contrast-enhanced ultrasound (CUS) imaging often varies between subjects, especially in patients with background cirrhosis. Various factors contribute to this variability, including the tumor blood flow, tumor size, internal echoes, and its location in livers with diffuse fibro-cirrhotic changes.

OBJECTIVE

Towards improving lesion detection, this study evaluates a vasodilator, hydralazine, to enhance the visibility of HCC by reducing its blood flow relative to the surrounding liver tissue.

METHODS

HCC were analyzed for tumor visibility measured for B-mode, CUS, and hydralazine-augmented-contrast ultrasound (HyCUS) in an autochthonous HCC rat model. 21 tumors from 12 rats were studied. B-mode and CUS images were acquired before hydralazine injection. Rats received an intravenous hydralazine injection of 5 mg/kg, then images were acquired 20 min later. Four rats were used as controls. The difference in echo intensity of the lesion and the surrounding tissue was used to determine the visibility index (VI).

RESULTS

The visibility index for HCC was found to be significantly improved with the use of HyCUS imaging compared to traditional B-mode and CUS imaging. The visibility index for HCC was 16.5 ± 2.8 for HyCUS, compared to 5.3 ± 4.8 for B-mode and 4.1 ± 3.8 for CUS. The differences between HyCUS and the other imaging modalities were statistically significant, with p-values of 0.001 and 0.02, respectively. Additionally, when compared to control cases, HyCUS showed higher discrimination of HCC (VI = 6.4 ± 1.2) with a p-value of 0.003, while B-mode (VI = 6.7 ± 1.4, p = 0.5) and CUS (VI = 6.4 ± 1.2, p = 0.3) showed lower discrimination.

CONCLUSION

Vascular blood flow modulation by hydralazine enhances the visibility of HCC. HyCUS offers a potential problem-solving method for detecting HCC when B-mode and CUS are unsuccessful, especially with background fibro-cirrhotic liver disease. Future evaluation of the approach in humans will determine its translatability for clinical applications.

Contrast-enhanced ultrasound for assessing blood flow modulation of hepatocellular carcinoma by hydralazine

Modulating aberrant tumor microvasculature provides unique opportunities for enhancing ultrasound imaging of hepatocellular carcinoma (HCC). This study aims to use contrast-enhanced ultrasound to evaluate the potential of a potent vasodilator, hydralazine, to attenuate blood flow in HCC while enhancing it in the surrounding liver tissue. The "steel effect," where blood flow is diverted from the lesion to the surrounding tissue aims to enhance lesion-tissue contrast. Methods: HCC was induced in six rats by oral ingestion of diethylnitrosamine for 12 weeks. 10 tumors were studied to assess the enhancement in HCC tumors and surrounding tissue. Contrast-enhanced ultrasound images (CEUS) of each tumor were acquired before and after hydralazine injection. The enhancement of images was analyzed for the qualitative and quantitative assessment of HCC enhancement. Peak enhancement (PE) was calculated, representing the maximum signal intensity reached during the transit of the contrast bolus for both the tumor and the surrounding tissue. Intravenous administration of hydralazine significantly reduced CEUS signals in HCC tumors. The visual examination of images showed that the enhancement of tumors dramatically decreased after hydralazine injection. On the other hand, the surrounding tissue showed an increased enhancement. PE for the HCC changed from (71.8 ± 5) pre hydralazine to (28.7± 4.9), a 61.7% reduction after hydralazine injection, p=0.01. Future studies validating the technique in clinical settings for enhancing lesion-tissue contrast may allow physicians greater precision and accuracy in HCC surveillance for early detection of small tumors.

Differential diagnosis of different types of solid focal liver lesions using two-dimensional shear wave elastography

BACKGROUND

The clinical management and prognosis differ between benign and malignant solid focal liver lesions (FLLs), as well as among different pathological types of malignant FLLs. Accurate diagnosis of the possible types of solid FLLs is important. Our previous study confirmed the value of shear wave elastography (SWE) using maximal elasticity (Emax) as the parameter in the differential diagnosis between benign and malignant FLLs. However, the value of SWE in the differential diagnosis among different pathological types of malignant FLLs has not been proved.

AIM

To explore the value of two-dimensional SWE (2D-SWE) using Emax in the differential diagnosis of FLLs, especially among different pathological types of malignant FLLs.

METHODS

All the patients enrolled in this study were diagnosed as benign, malignant or undetermined FLLs by conventional ultrasound. Emax of FLLs and the periphery of FLLs was measured using 2D-SWE and compared between benign and malignant FLLs or among different pathological types of malignant FLLs.

RESULTS

The study included 32 benign FLLs in 31 patients and 100 malignant FLLs in 96 patients, including 16 cholangiocellular carcinomas (CCCs), 72 hepatocellular carcinomas (HCCs) and 12 liver metastases. Thirty-five FLLs were diagnosed as undetermined by conventional ultrasound. There were significant differences between Emax of malignant (2.21 ± 0.57 m/s) and benign (1.59 ± 0.37 m/s) FLLs (P = 0.000), and between Emax of the periphery of malignant (1.52 ± 0.39 m/s) and benign (1.36 ± 0.44 m/s) FLLs (P = 0.040). Emax of liver metastases (2.73 ± 0.99 m/s) was significantly higher than that of CCCs (2.14 ± 0.34 m/s) and HCCs (2.14 ± 0.46 m/s) (P = 0.002). The sensitivity, specificity and accuracy were 71.00%, 84.38% and 74.24% respectively, using Emax > 1.905 m/s (AUC 0.843) to diagnose as malignant and 23 of 35 (65.74%) FLLs with undetermined diagnosis by conventional ultrasound were diagnosed correctly.

CONCLUSION

Malignant FLLs were stiffer than benign ones and liver metastases were stiffer than primary liver carcinomas. 2D-SWE with Emax was a useful complement to conventional ultrasound for the differential diagnosis of FLLs.

Multiparametric Ultrasound Approach Using a Tree-Based Decision Classifier for Inconclusive Focal Liver Lesions Evaluated by Contrast Enhanced Ultrasound

BACKGROUND

Multiparametric ultrasound (MPUS) is a concept whereby the examiner is encouraged to use the latest features of an ultrasound machine. The aim of this study was to reanalyze inconclusive focal liver lesions (FLLs) that had been analyzed via contrast enhanced ultrasound (CEUS) using the MPUS approach with the help of a tree-based decision classifier.

MATERIALS AND METHODS

We retrospectively analyzed FLLs that were inconclusive upon CEUS examination in our department, focusing our attention on samples taken over a period of two years (2017-2018). MPUS reanalysis followed a three-step algorithm, taking into account the liver stiffness measurement (LSM), time-intensity curve analysis (TIC), and parametric imaging (PI). After processing all steps of the algorithm, a binary decision tree classifier (BDTC) was used to achieve a software-assisted decision.

RESULTS

Area was the only TIC-CEUS parameter that showed a significant difference between malign and benign lesions with a cutoff of >-19.3 dB for washout phenomena (AUROC = 0.58, Se = 74.0%, Sp = 45.7%). Using the binary decision tree classifier (BDTC) algorithm, we correctly classified 71 out of 91 lesions according to their malignant or benignant status, with an accuracy of 78.0% (sensitivity = 62%, specificity = 45%, and precision = 80%).

CONCLUSIONS

By reevaluating inconclusive FLLs that had been analyzed via CEUS using MPUS, we managed to determine that 78% of the lesions were malignant and, in 28% of them, we established the lesion type.

Advances in liver US, CT, and MRI: moving toward the future

Over the past two decades, the epidemiology of chronic liver disease has changed with an increase in the prevalence of nonalcoholic fatty liver disease in parallel to the advent of curative treatments for hepatitis C. Recent developments provided new tools for diagnosis and monitoring of liver diseases based on ultrasound (US), computed tomography (CT), and magnetic resonance imaging (MRI), as applied for assessing steatosis, fibrosis, and focal lesions. This narrative review aims to discuss the emerging approaches for qualitative and quantitative liver imaging, focusing on those expected to become adopted in clinical practice in the next 5 to 10 years. While radiomics is an emerging tool for many of these applications, dedicated techniques have been investigated for US (controlled attenuation parameter, backscatter coefficient, elastography methods such as point shear wave elastography [pSWE] and transient elastography [TE], novel Doppler techniques, and three-dimensional contrast-enhanced ultrasound [3D-CEUS]), CT (dual-energy, spectral photon counting, extracellular volume fraction, perfusion, and surface nodularity), and MRI (proton density fat fraction [PDFF], elastography [MRE], contrast enhancement index, relative enhancement, T1 mapping on the hepatobiliary phase, perfusion). Concurrently, the advent of abbreviated MRI protocols will help fulfill an increasing number of examination requests in an era of healthcare resource constraints.

CEUS LI-RADS: a pictorial review

Contrast-enhanced ultrasound (CEUS) greatly improved the diagnostic accuracy of US in the detection and characterization of focal liver lesions (FLLs), and it is suggested and often included in many international guidelines as an important diagnostic tool in the imaging work-up of cirrhotic patients at risk for developing hepatocellular carcinoma (HCC). In particular, CEUS Liver Imaging Reporting and Data System (LI-RADS) provides standardized terminology, interpretation, and reporting for the diagnosis of HCC. The aim of this pictorial essay is to illustrate CEUS features of nodules discovered at US in cirrhotic liver according to LI-RADS categorization.

Super-Resolution Contrast-Enhanced Ultrasound Methodology for the Identification of In Vivo Vascular Dynamics in 2D

OBJECTIVES

The aim of this study was to provide an ultrasound-based super-resolution methodology that can be implemented using clinical 2-dimensional ultrasound equipment and standard contrast-enhanced ultrasound modes. In addition, the aim is to achieve this for true-to-life patient imaging conditions, including realistic examination times of a few minutes and adequate image penetration depths that can be used to scan entire organs without sacrificing current super-resolution ultrasound imaging performance.

METHODS

Standard contrast-enhanced ultrasound was used along with bolus or infusion injections of SonoVue (Bracco, Geneva, Switzerland) microbubble (MB) suspensions. An image analysis methodology, translated from light microscopy algorithms, was developed for use with ultrasound contrast imaging video data. New features that are tailored for ultrasound contrast image data were developed for MB detection and segmentation, so that the algorithm can deal with single and overlapping MBs. The method was tested initially on synthetic data, then with a simple microvessel phantom, and then with in vivo ultrasound contrast video loops from sheep ovaries. Tracks detailing the vascular structure and corresponding velocity map of the sheep ovary were reconstructed. Images acquired from light microscopy, optical projection tomography, and optical coherence tomography were compared with the vasculature network that was revealed in the ultrasound contrast data. The final method was applied to clinical prostate data as a proof of principle.

RESULTS

Features of the ovary identified in optical modalities mentioned previously were also identified in the ultrasound super-resolution density maps. Follicular areas, follicle wall, vessel diameter, and tissue dimensions were very similar. An approximately 8.5-fold resolution gain was demonstrated in vessel width, as vessels of width down to 60 μm were detected and verified (λ = 514 μm). Best agreement was found between ultrasound measurements and optical coherence tomography with 10% difference in the measured vessel widths, whereas ex vivo microscopy measurements were significantly lower by 43% on average. The results were mostly achieved using video loops of under 2-minute duration that included respiratory motion. A feasibility study on a human prostate showed good agreement between density and velocity ultrasound maps with the histological evaluation of the location of a tumor.

CONCLUSIONS

The feasibility of a 2-dimensional contrast-enhanced ultrasound-based super-resolution method was demonstrated using in vitro, synthetic and in vivo animal data. The method reduces the examination times to a few minutes using state-of-the-art ultrasound equipment and can provide super-resolution maps for an entire prostate with similar resolution to that achieved in other studies.

Contrast-enhanced ultrasound of hepatocellular carcinoma: where do we stand?

Contrast-enhanced ultrasound (CEUS) represents a significant breakthrough in ultrasonography (US), and it is being increasingly used for the evaluation of focal liver lesions (FLLs). CEUS is unique in that it allows non-invasive assessment of liver perfusion in real time throughout the vascular phase, which has led to dramatic improvements in the diagnostic accuracy of US in the detection and characterization of FLLs, the choice of therapeutic procedures, and the evaluation of response. Currently, CEUS is included as a part of the suggested diagnostic work-up of FLLs, including in cirrhotic patients with hepatocellular carcinoma, resulting in better patient management and cost-effective delivery of therapy.

Contrast-enhanced ultrasonography in differential diagnosis of focal gallbladder adenomyomatosis and gallbladder cancer

BACKGROUND

Focal gallbladder adenomyomatosis (ADM) is a common disease that mimics gallbladder cancer (GBC) on ultrasonography.

OBJECTIVE

Here we aim to assess the value of contrast-enhanced ultrasound (CEUS) in differentiating ADM from GBC.

METHODS

Forty-one histopathologically proven focal ADMs and 34 GBCs (≤T2 stage) were enrolled in the study. Lesion location, blood flow signals, contrast pattern and appearance on contrast-enhanced ultrasound (CEUS) were compared respectively.

RESULTS

Lesions were detected in fundus, body, neck at the rates of 61.0% (25/41), 26.8% (11/41) and 12.2% (5/41), respectively, in ADM patients, in comparison to 29.4% (10/34), 32.4% (11/34) and 38.2% (13/34), respectively, in GBC patients (p = 0.009). Blood flow signals were detected in 19.5% (8/41) of cases in ADMs, compared to 58.8% (20/34) in GBCs (p = 0.001). On CEUS, iso-enhancement, hypo-enhancement, intramural anechoic space and intactness of GB wall were detected in 41.5% (17/41), 39.0% (16/41), 56.1% (23/41) and 80.5% (33/41) cases of ADMs, in contrast to 17.6% (6/34), 20.6% (7/34), 20.6% (7/34) and 17.6% (6/34) of GBCs (p = 0.001, p = 0.001, p = 0.002, p < 0.001, respectively). The prior Youden's index were 0.81 based on intactness of GB wall on CEUS.

CONCLUSION

Combined with CEUS helps improve the differential diagnosis accuracy of focal gallbladder ADMs.

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

A cost-effectiveness analysis of the diagnostic strategies for differentiating focal nodular hyperplasia from hepatocellular adenoma

OBJECTIVES

We evaluated the cost-effectiveness of a gadoxetic acid-enhanced MRI (EOB-MRI) strategy compared with conventional MRI strategy and biopsy to differentiate focal nodular hyperplasia (FNH) from hepatocellular adenoma (HCA).

METHODS

A decision tree model was constructed to compare the cost-effectiveness of EOB-MRI, conventional MRI with extracellular contrast agents, and biopsy as the initial diagnostic modality in patients with incidentally detected focal liver lesions suspected of being FNH or HCA. We analysed the cost and effectiveness, i.e. probability of successful diagnosis of each strategy. Costs were based on utilisation rates and Medicare reimbursements in the USA and South Korea.

RESULTS

In the base case analysis of our decision tree model, the effectiveness of the three strategies was similar. The cost of the EOB-MRI strategy ($1283 in USA, $813 in South Korea) was lowest compared with the biopsy strategy ($1725 in USA, $847 in South Korea) and the conventional MRI strategy ($1750 in USA, $962 in South Korea). One-way, two-way and probabilistic sensitivity analysis showed unchanged results over an acceptable range.

CONCLUSIONS

EOB-MRI strategy is the most cost-effective strategy for differentiating FNH from HCA in patients with incidentally detected focal liver lesions in a non-cirrhotic liver.

KEY POINTS

• The effectiveness of the three strategies was similar. • The cost of the EOB-MRI strategy was lowest. • EOB-MRI strategy is the most cost-effective for differentiating FNH from HCA.

Contrast-enhanced US for characterization of focal liver lesions: a comprehensive meta-analysis

OBJECTIVES

This meta-analysis was performed to evaluate the accuracy of contrast-enhanced ultrasound (CEUS) in differentiating malignant from benign focal liver lesions (FLLs).

METHODS

Cochrane Library, PubMed and Web of Science databases were systematically searched and checked for studies using CEUS in characterization of FLLs. 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

Fifty-seven studies were included in this meta-analysis and the overall diagnostic accuracy in characterization of FLLs was as follows: pooled sensitivity, 0.92 (95%CI: 0.91-0.93); pooled specificity, 0.87 (95%CI: 0.86-0.88); diagnostic odds ratio, 104.20 (95%CI: 70.42-154.16). Subgroup analysis indicated higher diagnostic accuracy of the second-generation contrast agents (CAs) than the first-generation CA (Levovist; DOR: 118.27 vs. 62.78). Furthermore, Sonazoid demonstrated the highest diagnostic accuracy among three major CAs (SonoVue, Levovist and Sonazoid; DOR: 118.82 vs. 62.78 vs. 227.39). No potential publication bias was observed of the included studies.

CONCLUSION

CEUS is an accurate tool to stratify the risk of malignancy in FLLs. The second-generation CAs, especially Sonazoid may greatly improve diagnostic performance.

KEY POINTS

• CEUS shows excellent diagnostic accuracy in differentiating malignant from benign FLLs. • The second-generation CAs have higher diagnostic accuracy than first-generation CAs. • Sonazoid demonstrates the highest diagnostic accuracy among three major CAs.

Focal Liver Lesions: Computer-aided Diagnosis by Using Contrast-enhanced US Cine Recordings

Purpose To assess the performance of computer-aided diagnosis (CAD) systems and to determine the dominant ultrasonographic (US) features when classifying benign versus malignant focal liver lesions (FLLs) by using contrast material-enhanced US cine clips. Materials and Methods One hundred six US data sets in all subjects enrolled by three centers from a multicenter trial that included 54 malignant, 51 benign, and one indeterminate FLL were retrospectively analyzed. The 105 benign or malignant lesions were confirmed at histologic examination, contrast-enhanced computed tomography (CT), dynamic contrast-enhanced magnetic resonance (MR) imaging, and/or 6 or more months of clinical follow-up. Data sets included 3-minute cine clips that were automatically corrected for in-plane motion and automatically filtered out frames acquired off plane. B-mode and contrast-specific features were automatically extracted on a pixel-by-pixel basis and analyzed by using an artificial neural network (ANN) and a support vector machine (SVM). Areas under the receiver operating characteristic curve (AUCs) for CAD were compared with those for one experienced and one inexperienced blinded reader. A third observer graded cine quality to assess its effects on CAD performance. Results CAD, the inexperienced observer, and the experienced observer were able to analyze 95, 100, and 102 cine clips, respectively. The AUCs for the SVM, ANN, and experienced and inexperienced observers were 0.883 (95% confidence interval [CI]: 0.793, 0.940), 0.829 (95% CI: 0.724, 0.901), 0.843 (95% CI: 0.756, 0.903), and 0.702 (95% CI: 0.586, 0.782), respectively; only the difference between SVM and the inexperienced observer was statistically significant. Accuracy improved from 71.3% (67 of 94; 95% CI: 60.6%, 79.8%) to 87.7% (57 of 65; 95% CI: 78.5%, 93.8%) and from 80.9% (76 of 94; 95% CI: 72.3%, 88.3%) to 90.3% (65 of 72; 95% CI: 80.6%, 95.8%) when CAD was in agreement with the inexperienced reader and when it was in agreement with the experienced reader, respectively. B-mode heterogeneity and contrast material washout were the most discriminating features selected by CAD for all iterations. CAD selected time-based time-intensity curve (TIC) features 99.0% (207 of 209) of the time to classify FLLs, versus 1.0% (two of 209) of the time for intensity-based features. None of the 15 video-quality criteria had a statistically significant effect on CAD accuracy-all P values were greater than the Holm-Sidak α-level correction for multiple comparisons. Conclusion CAD systems classified benign and malignant FLLs with an accuracy similar to that of an expert reader. CAD improved the accuracy of both readers. Time-based features of TIC were more discriminating than intensity-based features. ^© RSNA, 2017 Online supplemental material is available for this article.

Inflammatory and multiple hepatocellular adenoma are associated with a higher BMI

AIM

To identify patient and lesion characteristics associated with the occurrence of single or multiple hepatocellular adenoma (HCA).

PATIENTS AND METHODS

Using a tertiary centre database, we retrospectively collected information on patient and lesion characteristics, management and follow-up of all patients with HCA included between 2001 and 2016. Patients were classified into three groups; patients with a single HCA, 2-9 HCA and at least 10 HCA.

RESULTS

A total of 458 patients were diagnosed with HCA, including 121 (26.4%) with single HCA, 235 (51.3%) with 2-9 HCA and 102 (22.3%) with at least 10 HCA. Significant differences in the mean BMI were found, with the highest BMI in patients with more than 10 HCA (P<0.05). The mean BMI was significantly higher in patients with inflammatory HCA compared with steatotic HCA (31 vs. 26, respectively, P<0.05). Steatotic HCA were more often single lesions (22/55, 40%), whereas patients with inflammatory HCA were often diagnosed with multiple lesions (122/166, 73%).

CONCLUSION

Our series show a significantly higher BMI and frequency of inflammatory HCA in patients with multiple HCA compared with single HCA.

Preparation and characterization of a novel silicon-modified nanobubble

Nanobubbles (NBs) opened a new field of ultrasound imaging. There is still no practical method to control the diameter of bubbles. In this study, we developed a new method to control the size by incorporating of silicon hybrid lipids into the bubble membrane. The range of particle size of resulting NBs is between 523.02 ± 46.45 to 857.18 ± 82.90, smaller than the conventional microbubbles. The size of resulting NBs increased with the decrease in amount of silicon hybrid lipids, indicating the diameter of NBs can be regulated through modulating the ratio of silicon hybrid lipids in the bubble shell. Typical harmonic signals could be detected. The in vitro and in vivo ultrasound imaging experiments demonstrated these silicon-modified NBs had significantly improved ultrasound contrast enhancement abilities. Cytotoxicity assays revealed that these NBs had no obvious cytotoxicity to the 293 cell line at the tested bubble concentration. Our results showed that the novel NBs could use as nanoscale ultrasound contrast agents, providing the foundation for NBs in future applications including contrast-enhanced imaging and drug/gene delivery.

Characterization of Focal Liver Lesions Indistinctive on B Mode Ultrasound: Benefits of Contrast-Enhanced Ultrasound

Aim. The aim of this prospective study was to evaluate the additional value of contrast-enhanced ultrasound (CEUS) in identifying and characterizing of focal liver lesions (FLLs) that are indistinctive on B mode ultrasound (BMUS). Methods. The study focused on 70 consecutive patients (male 46, female 24; mean age, 53.1 years ± 10). All lesions were detected by MRI but could not be clearly visualized by BMUS. CEUS was performed by injected SonoVue® (Bracco Imaging Spa, Milan, Italy) as a quick bolus into the antecubital vein. All lesions were proved by pathologic and MRI findings as primary or metastatic hepatic malignancies. Results. On CEUS, 45 (64.2%) FLLs displayed arterial hyperenhancement and 55 (78.5%) lesions showed hypoenhancement in portal venous and late phase (PVLP). Homogeneous and complete hyperenhancement pattern during the arterial phase is highly suspicious for HCC in liver cirrhosis (96.8%). Arterial isoenhancement and early washout during PVLP are characteristic for metastasis (73.3%). For recurrence lesions, arterial hyperenhancement and isoenhancement during PVLP are more common (60%). Conclusion. CEUS may provide added diagnostic values in FLLs appearing indistinctive on BMUS. Presence of early arterial enhancement and washout during PVLP may be helpful for detection of those lesions.

Detection of liver metastases in cancer patients with geographic fatty infiltration of the liver: the added value of contrast-enhanced sonography

Purpose

The aim of this study is to assess the role of contrast-enhanced ultrasonography (CEUS) in the detection of liver metastases in cancer patients with geographic liver fatty deposition on greyscale ultrasonography (US).

Methods

Thirty-seven consecutive cancer patients (24 women and 13 men; age, 33 to 80 years; mean, 58.1 years) with geographic liver fatty deposition, but without any detectable focal liver lesion on greyscale US, underwent sulphur hexafluoride-enhanced US. Two readers reported by consensus the presence, size, and location of any detected lesion. All patients underwent magnetic resonance imaging (MRI) as a confirmatory study. Sensitivity, specificity, positive and negative predictive values (PPV and NPV), and accuracy were calculated.

Results

Seven focal liver lesions (size, 4 to 10 mm; mean, 6.1 mm) were detected in 4/37 patients (10.8%): four metastases (size, 5 to 10 mm; mean, 6.7 mm) were detected both by CEUS and MRI, with one hemangioma and two cysts (size range, 4 to 6 mm; mean, 5.3 mm) detected by MRI only. In 1/37 patients (2.7%), CEUS misdiagnosed geographic fatty change as three metastases. In 32/37 patients (86.5%), no lesions were detected. Sensitivity, specificity, PPV, NPV, and accuracy of CEUS were 100% (95% confidence Interval [CI], 1.000 to 1.000), 97.1% (95% CI, 0.914 to 1.027), 75%, 100%, and 97.3%, respectively. No statistically significant differences were found between CEUS and MRI in the detection of focal liver lesions (P=0.480), whereas both of them performed better than baseline US (P<0.001).

Conclusion

CEUS improves the detection of liver metastases in cancer patients with geographic liver fatty deposition on greyscale US.

Contrast-Enhanced Ultrasound in Focal Liver Lesions: Where Do We Stand?

Contrast-enhanced ultrasound (CEUS) represents a significant breakthrough in sonography, and it is being increasingly used for the evaluation of focal liver lesions (FLLs). Currently, CEUS is included as a part of the suggested diagnostic workup of FLLs, resulting in a better patient management and delivering cost-effective therapy. After a brief technical note, contrast-enhancement patterns of different types of benign and malignant FLLs, along with hepatic pseudolesions, are described and discussed based on our experience and literature data. At the same time, the most recent concepts and the use of CEUS in different clinical settings are presented.

Contrast enhancement ultrasound application in focal liver lesions characterization: a retrospective study about guidelines application (SOCEUS-CEUS survey)

INTRODUCTION

The SOCEUS survey aims to evaluate how contrast-enhanced ultrasound (CEUS) is effectively used in the focal liver lesions characterization.

MATERIALS AND METHODS

In the survey were involved Verona, Brescia and Trieste Radiological Centers and Arezzo and Bologna Non-radiological Centers. Inclusion criteria were liver focal lesion detection at conventional ultrasound and studied by means of CEUS, with or without CT or MRI examinations, done previous or subsequent to CEUS.

RESULTS

1069 forms were collected. Patients with benign lesions, who did not undergo any other studies, were 255/561 (45.5 %). Among patients with diagnosis of hemangioma at CEUS, those who had no other investigations were 129/267 (48.3 %). Patients with malignant lesions who had studies pre-CEUS (CT and/or MRI) were 328/508 (65 %), whereas those who had examinations post-CEUS (CT and/or MRI) were 218/508 (42.9 %). Concordance rate between CEUS and CT investigations pre- and post-CEUS was, respectively, 66 and 89 %. Concordance rate between CEUS and MRI studies pre- and post-CEUS was, respectively, 87.5 and 81.5 %.

CONCLUSION

This study proves contrast-enhanced ultrasound correct application in the involved centers.

2-tier in-plane motion correction and out-of-plane motion filtering for contrast-enhanced ultrasound

OBJECTIVES

Contrast-enhanced ultrasound (CEUS) cines of focal liver lesions (FLLs) can be quantitatively analyzed to measure tumor perfusion on a pixel-by-pixel basis for diagnostic indication. However, CEUS cines acquired freehand and during free breathing cause nonuniform in-plane and out-of-plane motion from frame to frame. These motions create fluctuations in the time-intensity curves (TICs), reducing the accuracy of quantitative measurements. Out-of-plane motion cannot be corrected by image registration in 2-dimensional CEUS and degrades the quality of in-plane motion correction (IPMC). A 2-tier IPMC strategy and adaptive out-of-plane motion filter (OPMF) are proposed to provide a stable correction of nonuniform motion to reduce the impact of motion on quantitative analyses.

MATERIALS AND METHODS

A total of 22 cines of FLLs were imaged with dual B-mode and contrast specific imaging to acquire a 3-minute TIC. B-mode images were analyzed for motion, and the motion correction was applied to both B-mode and contrast images. For IPMC, the main reference frame was automatically selected for each cine, and subreference frames were selected in each respiratory cycle and sequentially registered toward the main reference frame. All other frames were sequentially registered toward the local subreference frame. Four OPMFs were developed and tested: subsample normalized correlation (NC), subsample sum of absolute differences, mean frame NC, and histogram. The frames that were most dissimilar to the OPMF reference frame using 1 of the 4 above criteria in each respiratory cycle were adaptively removed by thresholding against the low-pass filter of the similarity curve. Out-of-plane motion filter was quantitatively evaluated by an out-of-plane motion metric (OPMM) that measured normalized variance in the high-pass filtered TIC within the tumor region-of-interest with low OPMM being the goal. Results for IPMC and OPMF were qualitatively evaluated by 2 blinded observers who ranked the motion in the cines before and after various combinations of motion correction steps.

RESULTS

Quantitative measurements showed that 2-tier IPMC and OPMF improved imaging stability. With IPMC, the NC B-mode metric increased from 0.504 ± 0.149 to 0.585 ± 0.145 over all cines (P < 0.001). Two-tier IPMC also produced better fits on the contrast-specific TIC than industry standard IPMC techniques did (P < 0.02). In-plane motion correction and OPMF were shown to improve goodness of fit for pixel-by-pixel analysis (P < 0.001). Out-of-plane motion filter reduced variance in the contrast-specific signal as shown by a median decrease of 49.8% in the OPMM. Two-tier IPMC and OPMF were also shown to qualitatively reduce motion. Observers consistently ranked cines with IPMC higher than the same cine before IPMC (P < 0.001) as well as ranked cines with OPMF higher than when they were uncorrected.

CONCLUSION

The 2-tier sequential IPMC and adaptive OPMF significantly reduced motion in 3-minute CEUS cines of FLLs, thereby overcoming the challenges of drift and irregular breathing motion in long cines. The 2-tier IPMC strategy provided stable motion correction tolerant of out-of-plane motion throughout the cine by sequentially registering subreference frames that bypassed the motion cycles, thereby overcoming the lack of a nearly stationary reference point in long cines. Out-of-plane motion filter reduced apparent motion by adaptively removing frames imaged off-plane from the automatically selected OPMF reference frame, thereby tolerating nonuniform breathing motion. Selection of the best OPMF by minimizing OPMM effectively reduced motion under a wide variety of motion patterns applicable to clinical CEUS. These semiautomated processes only required user input for region-of-interest selection and can improve the accuracy of quantitative perfusion measurements.

Activity-based cost analysis of contrast-enhanced ultrasonography (CEUS) related to the diagnostic impact in focal liver lesion characterisation

PURPOSE

This study was done to assess the clinical-diagnostic impact and cost of contrast-enhanced ultrasound (CEUS) versus computed tomography (CT) and magnetic resonance (MR) imaging in the characterisation of focal liver lesions.

MATERIALS AND METHODS

CEUS with sulphur hexafluoride-filled microbubbles (SonoVue bolus 2.4 ml) was performed in 157 patients with 160 focal liver lesions identified by other diagnostic techniques. CEUS images were obtained during the arterial (15 to 35 s from contrast injection), portal venous (40 to 70 s) and late phase (up to 300 s from microbubble injection). Contrast-enhanced CT was performed with a 64-row multidetector CT. MRI was performed before and after administration of the liver-specific contrast agent gadobenate dimeglumine (Gd-BOPTA). A patient-by-patient activity-based cost analysis was performed.

RESULTS

CEUS led to a change in the diagnostic workup in 131/157 patients (83.4 %) and in the therapeutic workup in 93/157 patients (59.2 %). CEUS allowed for the final diagnosis to be established in 133/157 patients (84.7 %). The full cost of CEUS was lower than that of contrast-enhanced CT and MR imaging.

CONCLUSIONS

CEUS determined a change in the diagnostic and therapeutic workup in the characterisation of focal liver lesions and reduced the full costs of the diagnostic process.

MAIN MESSAGES

• CEUS allows a correct diagnosis in more than 80 % of focal liver lesions. • CEUS has a significant impact on the diagnosis of focal liver lesions. • CEUS examination of focal liver lesions reduces total costs. • Dynamic MR with hepato-specific contrast medium remains the reference standard for lesion characterisation. • CEUS is low-cost, versatile and accurate in the characterisation of focal liver lesions.

Diagnostic workup of liver lesions: too long time with too many examinations

OBJECTIVE

Liver mass lesions are often detected incidentally. Subsequent imaging examinations and surveillance are not only expensive, but may also cause unnecessary concern to patients. The aim of this study was to evaluate retrospectively the possible delay in acquiring the diagnosis of liver mass lesions, and to estimate the number of imaging examinations performed during the diagnostic workup.

PATIENTS AND METHODS

The study comprised 200 patients with liver mass lesion of unknown etiology. The time needed from referral to final diagnosis was assessed. All imaging examinations and biopsy findings (if available) during the diagnostic workup were recorded.

RESULTS

Out of the 200 lesions, 133 were malignant, 65 with hepatocellular cancer and 26 with cholangiocarcinoma. All except one were diagnosed within 8 weeks. Of the 67 benign lesions, there were 20 focal nodular hyperplasias and 20 hemangiomas. For the benign lesions, in 37% the diagnostic workup took >8 weeks. Repeated examinations were more common in benign lesions; but often redundant in both benign and malignant conditions in retrospect analysis.

CONCLUSIONS

To confirm the diagnosis, benign lesions required more follow-up time and more repeated imaging examinations than malignant ones. A long surveillance for liver mass lesions in fear of malignancy seems not to be necessary, since virtually all malignant lesions were diagnosed within 8 weeks. Evaluating all lesions in a multidisciplinary team right from the beginning is advocated by a prospective study design.

Combination of 2- and 3-dimensional contrast-enhanced transvaginal sonography for diagnosis of small adnexal masses

OBJECTIVES

The purpose of this study was to evaluate the efficacy of the combination of 2-dimensional (2D) and 3-dimensional (3D) contrast-enhanced sonography in discriminating between benign and malignant small adnexal masses.

METHODS

Selected patients were evaluated with both 2D and 3D contrast-enhanced sonography after conventional sonography before undergoing any surgery. Time-intensity curves for 2D contrast-enhanced sonography were constructed by using contrast-enhanced sonographic software. A vascular perfusion characteristic analysis was achieved by 2D and 3D contrast-enhanced sonography. Results were finally verified by surgery.

RESULTS

Forty-seven cases of benign and 10 cases of malignant small adnexal masses were discovered. Significant differences in perfusion patterns, time-intensity curve shapes for 2D contrast-enhanced sonography, grayscale contrast-enhanced sonography, and blood flow imaging on 3D contrast-enhanced sonography were observed between benign and malignant masses (P< .05). Two-dimensional contrast-enhanced sonography, 3D contrast-enhanced sonography, parallel combination of 2D and 3D contrast-enhanced sonography, and serial combination of 2D and 3D contrast-enhanced sonography all reached diagnostic sensitivity of 100% for discriminating benign from malignant masses, whereas specificity values were 61.7%, 63.8%, 68.1%, and 57.4%, respectively. Areas under the receiver operating characteristic curves were 0.809, 0.819, 0.840, and 0.787.

CONCLUSIONS

Two-dimensional contrast-enhanced sonography is of high value in distinguishing malignant from benign small adnexal masses; 3D contrast-enhanced sonography provides richer and more useful information for evaluation of these masses. Diagnostic sensitivity of 100% can be achieved when using a serial combination of 2D and 3D contrast-enhanced sonography, although specificity needs further improvement.

Approach to improving sonographic visualization of elongated left lobe of the liver and its implications

PURPOSE

To determine whether visualization of the elongated left lobe of the liver can be improved by distending the stomach with water and the implications of this technique.

METHODS

Forty-three out of 87 patients with elongated left lobe of the liver found at abdominal CT were included in this study after obtaining informed consent. Their livers were examined using ultrasound before and after drinking water. The left lobe of the liver was scanned from the subxiphoid and left subcostal approaches, with the sound beam directed to the spleen and the left lobe of the liver neighboring or behind the stomach; the elongated left lobe of the liver overlying the spleen was detected by scanning from the 9th-11th intercostal approach of the left flank.

RESULTS

The overall visualization of the elongated left lobe of the liver before and after filling the stomach with water was 4.7 % (2/43) and 100.0 % (43/43), respectively (P < 0.001); and the overall visualization of the spleen before and after filling the stomach with water was 4.7 % (2/43) and 100.0 % (43/43), respectively (P < 0.001).

CONCLUSION

Distending the stomach with sufficient water can substantially improve visualization of elongated left lobe of the liver at ultrasound, potentially improving detection of tumors in the liver and preventing misdiagnosis.

Characterization of incidental liver lesions: comparison of multidetector CT versus Gd-EOB-DTPA-enhanced MR imaging

As a result of recent developments in imaging modalities and wide spread routine medical checkups and screening, more incidental liver lesions are found frequently on US these days. When incidental liver lesions are found on US, physicians have to make a decision whether to just follow up or to undergo additional imaging studies for lesion characterization. In order to choose the next appropriate imaging modality, the diagnostic accuracy of each imaging study needs to be considered. Therefore, we tried to compare the accuracy of contrast-enhanced multidetector CT (MDCT) and Gd-EOB-DTPA-enhanced MRI for characterization of incidental liver masses. We included 127 incidentally found focal liver lesions (94 benign and 33 malignant) from 80 patients (M∶F = 45∶35) without primary extrahepatic malignancy or chronic liver disease. Two radiologists independently reviewed Gd-EOB-DTPA-enhanced MRI and MDCT. The proportion of confident interpretations for differentiation of benign and malignant lesions and for the specific diagnosis of diseases were compared. The proportion of confident interpretations for the differentiation of benign and malignant lesions was significantly higher with EOB-MRI(94.5%-97.6%) than with MDCT (74.0%-92.9%). In terms of specific diagnosis, sensitivity and accuracy were significantly higher with EOB-MRI than with MDCT for the diagnosis of focal nodular hyperplasia (FNH) and focal eosinophilic infiltration. The diagnoses of the remaining diseases were comparable between EOB-MRI and MDCT. Hence, our results suggested that Gd-EOB-MRI may provide a higher proportion of confident interpretations than MDCT, especially for the diagnosis of incidentally found FNH and focal eosinophilic infiltration.