Contrast-Enhanced Ultrasound Quantification Assessment of Focal Fatty Variations in Liver Parenchyma: Challenging the Traditional Qualitative Paradigm of Uniform Enhancement With Adjacent Parenchyma.

OBJECTIVES: The purpose of this study was to quantify contrast-enhanced ultrasound enhancement of focal fatty sparing (FFS) and focal fatty infiltration (FFI) and compare it with adjacent liver parenchyma. METHODS: This was a retrospective observational study yielding 42 cases in the last 4 years. Inclusion criteria were a focal liver lesion, adequate video availability, and an established diagnosis of FFS or FFI based on clinical or imaging follow-up or a second modality. Contrast-enhanced ultrasound examinations were performed with a standard low-mechanical index technique. Commercially available software calculated quantitative parameters for a focal liver lesion and a reference area of liver parenchyma, producing relative indices. RESULTS: In total, 42 patients were analyzed (19 male) with a median age of 18 (interquartile range, 42) years and a median lesion diameter of 30 (interquartile range, 16) mm. The cohort included 26 with FFS and 16 with FFI. Subjectively assessed, 27% of FFS and 25% of FFI were hypoenhancing in the arterial phase, and 73% of FFS and 75% of FFI were isoenhancing. In the venous and delayed phases, all lesions were isoenhancing. The peak enhancement (P = .001), wash-in area under the curve (P < .01), wash-in rate (P = .023), and wash-in perfusion index (P = .001) were significantly lower in FFS compared with adjacent parenchyma but not the mean transit time. In the FFI subgroup, no significant difference was detected. Comparing relative parameters, only the wash-in rate was significantly (P = .049) lower in FFS than FFI. The mean follow-up was 2.8 years. CONCLUSIONS: Focal fatty sparing shows significantly lower and slower enhancement than the liver parenchyma, whereas FFI enhances identically. Focal fatty sparing had a significantly slower enhancement than FFI.

Emerging contrast-enhanced ultrasound applications in children.

Ultrasound contrast agent (UCA) use in radiology is expanding beyond traditional applications such as evaluation of liver lesions, vesicoureteral reflux and echocardiography. Among emerging techniques, 3-D and 4-D contrast-enhanced ultrasound (CEUS) imaging have demonstrated potential in enhancing the accuracy of voiding urosonography and are ready for wider clinical adoption. US contrast-based lymphatic imaging has been implemented for guiding needle placement in MR lymphangiography in children. In adults, intraoperative CEUS imaging has improved diagnosis and assisted surgical management in tumor resection, and its translation to pediatric brain tumor surgery is imminent. Because of growing interest in precision medicine, targeted US molecular imaging is a topic of active preclinical research and early stage clinical translation. Finally, an exciting new development in the application of UCA is in the field of localized drug delivery and release, with a particular emphasis on treating aggressive brain tumors. Under the appropriate acoustic settings, UCA can reversibly open the blood-brain barrier, allowing drug delivery into the brain. The aim of this article is to review the emerging CEUS applications and provide evidence regarding the feasibility of these applications for clinical implementation.

European Federation of Societies for Ultrasound in Medicine and Biology (EFSUMB): An Update on the Pediatric CEUS Registry on Behalf of the "EFSUMB Pediatric CEUS Registry Working Group".

The European Federation of Ultrasound in Medicine and Biology (EFSUMB) created the "EFSUMB Pediatric Registry" (EFSUMB EPR) with the purpose of collecting data regarding the intravenous application of pediatric contrast-enhanced ultrasound (CEUS). The primary aim was to document the current clinical practice and usefulness of the technique and secondarily to assess CEUS safety in children. We issue the preliminary results of this database and examine the overall practice of CEUS in children in Europe.

Reducing the Number of Measurements in Liver Point Shear-Wave Elastography: Factors that Influence the Number and Reliability of Measurements in Assessment of Liver Fibrosis in Clinical Practice.

Purpose To identify the minimum number of measurements required for the noninvasive assessment of liver fibrosis by using point shear-wave elastography (pSWE) and determine whether the use of a reliability indicator such as interquartile range [IQR]-to-median ratio will affect diagnostic performance. Materials and Methods Ten liver shear-wave velocity (SWV) measurements by pSWE were obtained in 232 participants. Interclass correlation coefficients (ICC) between the median of the first two through the first nine measurements and all 10 measurements were calculated; the minimum number of measurements with ICC greater than 0.95 versus all 10 measurements was determined. The diagnostic performance of the minimum number of measurements and 10 measurements in identifying significant (Ishak stage, ≥3) and severe fibrosis or cirrhosis (Ishak stage, ≥5) was compared by using areas under the receiver operating characteristic curve. These were compared between measurements that demonstrated higher or lower reliability (IQR-to-median ratio of ≤ 30% and IQR-to-median ratio of > 30%, respectively). Results Compared with 10 measurements, a minimum of six SWV measurements was required. The overall area under the curve for diagnosing significant (areas under the receiver operating characteristic curve, 0.828 vs 0.839; P = .487) and severe fibrosis or cirrhosis (0.953 vs 0.969, respectively; P = .145) did not differ according to number of measurements (six vs 10); a median of six measurements resulted in only limited disagreement (nine of 232 [3.9%]) versus histologic evaluation. When using 10 measurements, higher reliability measurements showed a lower percentage of discordance between pSWE and significant fibrosis and severe fibrosis or cirrhosis (22 [14.7%] and three [2.0%] of 150 cases, respectively) compared with lower reliability measurements (26 [31.7%] and eight [9.8%] of 82 cases, respectively). Significant fibrosis was an independent predictor for lower reliability (hazard ratio, 2.22; P < .020). Conclusion A limited number of SWV measurements (median six vs median 10) were required for the assessment of liver fibrosis by using pSWE. The number of measurements had less influence on the diagnostic accuracy compared with lower reliability measurements. © RSNA, 2018 Online supplemental material is available for this article.

Retrospective Analysis of the Safety and Cost Implications of Pediatric Contrast-Enhanced Ultrasound at a Single Center.

OBJECTIVE: Because of concern over medical ionizing radiation exposure of children, contrast-enhanced ultrasound (CEUS) has generated interest as an inexpensive, ionizing radiation-free alternative to CT and MRI. CEUS has received approval for pediatric hepatic use but remains off-label for a range of other applications. The purposes of this study were to retrospectively analyze adverse incidents encountered in pediatric CEUS and to assess the financial benefits of reducing the number of CT and MRI examinations performed. MATERIALS AND METHODS: All pediatric (patients 18 years and younger) CEUS examinations performed between January 2008 and December 2015 were reviewed. All immediate reactions deemed due to contrast examinations were documented in radiology reports. Electronic patient records were examined for adverse reactions within 24 hours not due to an underlying pathologic condition. With tariffs from the U.K. National Institute of Clinical Excellence analysis, CEUS utilization cost ($94) was compared with the CT ($168) and MRI ($274) costs of the conventional imaging pathway. RESULTS: The records of 305 pediatric patients (187 boys, 118 girls; age range, 1 month-18 years) undergoing CEUS were reviewed. Most of the studies were for characterizing liver lesions (147/305 [48.2%]) and trauma (113/305 [37.1%]); the others were for renal, vascular, and intracavitary assessment (45/305 [14.8%]). No immediate adverse reactions occurred. Delayed adverse reactions occurred in two patients (2/305 [0.7%]). These reactions were transient hypertension and transient tachycardia. Neither was symptomatic, and both were deemed not due to the underlying disorder. The potential cost savings of CEUS were $74 per examination over CT and $180 over MRI. CONCLUSION: Pediatric CEUS is a safe and potentially cost-effective imaging modality. Using it allows reduction in the ionizing radiation associated with CT and in the gadolinium contrast administration, sedation, and anesthesia sometimes required for MRI.

Contrast-enhanced US-guided Interventions: Improving Success Rate and Avoiding Complications Using US Contrast Agents.

Ultrasonography (US) is an established modality for intervention. The introduction of microbubble US contrast agents (UCAs) has the potential to further improve US imaging for intervention. According to licensing, UCAs are currently approved for clinical use in restricted situations, but many additional indications have become accepted as having clinical value. The use of UCAs has been shown to be safe, and there is no risk of renal toxic effects, unlike with iodinated or gadolinium contrast medium. Broadly speaking, UCAs can be injected into the bloodstream (intravascular use) or instilled into almost any accessible body cavity (endocavitary use), either in isolation or synchronously. In microvascular applications, contrast-enhanced US (CEUS) enhances delineation of necrotic areas and the vascularized target to improve real-time targeting. The ability of CEUS to allow true assessment of vascularity has also been used in follow-up of devascularizing intervention. In macrovascular applications, real-time angiographic images can be obtained with CEUS without nephrotoxic effects or radiation. In endocavitary applications, CEUS can achieve imaging similar to that of iodinated contrast medium-based fluoroscopy; follow-up to intervention (eg, tubography and nephrostography) can be performed at the bedside, which may be advantageous. The use of UCAs is a natural progression in US-guided intervention. The aim of this article is to describe the indications, contraindications, and techniques of using UCAs as an adjunctive tool for US-guided interventional procedures to facilitate effective treatment, improve complication management, and increase the overall success of interventional procedures. Online supplemental material is available for this article. ©RSNA, 2016.

Reproducibility of 2-Dimensional Shear Wave Elastography Assessment of the Liver: A Direct Comparison With Point Shear Wave Elastography in Healthy Volunteers.

OBJECTIVES: Two-dimensional shear wave elastography (2D-SWE) imaging for the noninvasive assessment of tissue stiffness was assessed for reproducibility in healthy volunteers in quantifying liver elasticity, compared with an established point shear wave elastography (p-SWE) technique also known as virtual touch quantification (VTQ) (SIEMENS). METHODS: Eleven healthy volunteers were examined by four experienced operators on two occasions, separated by two weeks (sessions A and B). Ten 2D-SWE using LOGIQ E9 and p-SWE measurements using VTQ (in meters per second) were consecutively taken from deep portions of liver segments 5 or 6 away from vascular structures, using standard techniques. Inter- and intra-observer agreement was assessed by intraclass coefficient (ICC). RESULTS: A total of 880 2D-SWE and p-SWE velocities were recorded. Mean values from the four operators ranged between 1.188 and 1.196 m/s for 2D-SWE and 1.170 to 1.207 m/s for p-SWE. Interobserver reproducibility was good for both sessions with ICCs of 0.88 and 0.93 (2D-SWE) and 0.87 and 0.93 (p-SWE). The overall intra-operator reproducibility between sessions A and B was good for both p-SWE and 2D-SWE with ICC of 0.87 and 0.83, respectively. For inter- and intra-observer variability, the ICC was more than or equal to 0.71, indicating that the results were reliable. There was a strong and significant correlation between the 2D-SWE and p-SWE measurements (r = 0.87, P = .0006), but their velocities did not agree equally across different velocities. CONCLUSIONS: Two-dimensional SWE using LOGIQ E9 is a reliable and reproducible method for measuring elasticity in healthy volunteers and has a similar degree of reliability as p-SWE using VTQ, but absolute measurements from the two techniques should not be used interchangeably.

Cortical necrosis secondary to trauma in a child: contrast-enhanced ultrasound comparable to magnetic resonance imaging.

Cortical necrosis is an uncommon cause of renal impairment and is rarely a consequence of blunt abdominal trauma. We present a case of unilateral traumatic acute cortical necrosis in a child demonstrated on contrast-enhanced US with confirmation on MRI. Contrast-enhanced US provides a rapid, accurate evaluation of renal parenchyma abnormalities in blunt abdominal trauma in children without exposure to ionising radiation or the risk of sedation.

Comparison Between Different Manufacturers' 2-D and Point Shear Wave Elastography Techniques in Staging Liver Fibrosis in Chronic Liver Disease Using Liver Biopsy as the Reference Standard: A Prospective Study.

The purpose of this study was to assess the utility of 2-D shear wave elastography (SWE) in assessing liver fibrosis in patients with chronic liver disease by comparing its performance with that of point shear wave elastography (pSWE) using liver histological staging as the reference standard. In this ethics committee-approved, single-institution prospective study, pSWE and 2-D SWE velocity measurements were obtained in 121 adult patients (age: 18-70 y, median: 45 y) immediately before a liver biopsy for chronic liver disease. Shear wave velocity (SWV) and Ishak scores were compared using the Kruskal-Wallis test, Spearman's correlation and receiver operating characteristic (ROC) curve analysis. Youden's index was used to determine the optimal cutoff point. There was no technical failure using pSWE and 2-D SWE. The mean difference for SWV between pSWE and 2-D SWE was 0.0223 (limits of agreement: -1.1009, 1.1145). Values for both pSWE and 2-D SWE were significantly correlated with fibrosis stage (Spearman's ρ = 0.606, p < 0.0001; ρ = 0.722, p < 0.001 respectively). The area under the ROC curve differentiating F ≥3 was 0.855 (95% confidence interval: 0.778-0.932) for pSWE and 0.884 (95% CI: 0.817-0.951) for 2-D SWE. The AUC for differentiating F ≥5 was 0.890 (95% CI: 0.826-0.954) for pSWE and 0.926 (95% CI: 0.88-0.973) for 2-D SWE. This study indicates that 2-D SWE provides feasible and accurate assessment of liver fibrosis, comparable to that provided by pSWE from two different manufacturers' machines.

A pictorial review of the utility of CEUS in thoracic biopsies.

Lung cancer is one of the commonest malignancies worldwide and necessitates both early and personalised treatment. A key requirement is histological sampling with immunohistochemistry obtained usually from percutaneous biopsy. Conventionally thoracic biopsies are performed using CT guidance, but more recently, there has been development of physician led ultrasound biopsy for pleural lesions. Contrast-enhanced ultrasound (CEUS) has been increasingly used in interventional procedures and is able to offer benefits for thoracic biopsies including improving lesional visualisation and characterisation, targeting viable tissue and avoiding critical vascular structures as well as evaluating for the presence of post-procedural complications. This educational review aims to benefits of the role of CEUS in thoracic biopsies.

The role of contrast-enhanced ultrasound (CEUS) in the evaluation of scrotal trauma: a review.

Testicular trauma is common, usually trivial and rarely requires hospital attendance, but if it does, then imaging becomes essential as scrotal assessment may be difficult due to pain and/or scrotal disruption. Ultrasound (US) assumes a crucial role as other cross-sectional modalities have a limited use in the acute presentation. Despite the acceptable accuracy of conventional US techniques, there are limitations which hinder a thorough evaluation, critically the assessment of tissue viability, crucial for clinical management and prognosis. Contrast-enhanced ultrasound (CEUS) has been shown to offer improved flow visualisation and tissue perfusion compared with conventional Doppler techniques. CEUS can accurately and confidently demonstrate the viability of testicular parenchyma, delineate fracture lines and haematomas and guide treatment for testis-sparing surgery or orchidectomy. The purpose of this review is to present the literature, familiarise physicians with the principles of CEUS and findings of scrotal trauma and illustrate the main abnormalities through characteristic and educative cases.

Vascularity of Intra-testicular Lesions: Inter-observer Variation in the Assessment of Non-neoplastic Versus Neoplastic Abnormalities After Vascular Enhancement With Contrast-Enhanced Ultrasound.

The aim of this study is to assess the additional benefit of contrast-enhanced ultrasound (CEUS) over conventional ultrasonography (US) in identifying intra-testicular abnormalities among observers of different experiences. In this study, 91 focal testicular lesions (46 neoplastic, 45 non-neoplastic) imaged with gray-scale US/Doppler US and CEUS were classified using a 5-point scale. Three experienced and four inexperienced observers rated each lesion using gray-scale/color Doppler US alone and then with the addition of CEUS. Improved diagnostic specificity and accuracy with the addition of CEUS was observed for both experienced (specificity: 71.1% vs. 59.3%, p = 0.005; accuracy: 83.5% vs. 76.9%, p = 0.003) and inexperienced observers (specificity: 75.6% vs. 51.7%, p = 0.005; accuracy: 80.2% vs. 72.0%, p < 0.001). Significant inter-observer variability between the experienced and inexperienced observers when assessing conventional US alone was eliminated with the addition of CEUS. CEUS improves diagnostic accuracy of focal intra-testicular lesions for both experienced and inexperienced observers and reduces inter-observer variability in inexperienced operators.

Complications from percutaneous microwave ablation of liver tumours: a pictorial review.

Percutaneous microwave ablation of liver tumours is a well-established technique that has been proven to be effective in the curative and palliative treatment of small volume primary and secondary liver tumours. Microwave ablation is designed to achieve larger areas of necrosis compared to radiofrequency ablation and has a good safety profile among liver tumour treatments. Mortality is unreported and major complications are rare. Knowledge of potential complications is essential for interventional radiologists performing liver ablation in order to reduce patient morbidity. The aim of this review is to illustrate major complications post microwave ablation in a pictorial format as well as a discussion on how best to avoid these complications.

Percutaneous drainage of a parotid gland abscess under contrast-enhanced ultrasound guidance: A case report.

A parotid gland abscess is uncommon and if not responding to conservative management, requires surgical intervention. However, surgery is invasive with the risk of complicating facial nerve damage and possible poor cosmetic outcome. We present a case of a parotid gland abscess in association with an underlying Warthin's tumour requiring percutaneous drainage, as patient co-morbidity precluded a safe surgical approach. Percutaneous drainage was aided by a contrast-enhanced ultrasound examination, which permitted delineation of the fluid aspects of the collection from the underlying tumour and allowed successful percutaneous ultrasound-guided aspiration without complication.

Contrast-enhanced ultrasound (CEUS) of the abdominal vasculature.

Vascular diseases account for a significant proportion of abdominal pathology and represent a common referral source for abdominal ultrasonographic examinations. B-mode, color Doppler, and spectral Doppler analyses are well-established in the evaluation of abdominal blood vessels although they may occasionally be limited by lower sensitivity for slow flow visualization or the deeper location of abdominal vascular structures. The introduction of microbubbles as ultrasonographic contrast agents has rendered contrast-enhanced ultrasound (CEUS), a valuable complementary ultrasonographic technique, which is capable of addressing clinically significant problems and guiding patient management. The purpose of this pictorial review is to analyze the use of CEUS in the evaluation of abdominal vascular pathology and illustrate such applications by presenting representative images. Pathology discussed includes abdominal aortic aneurysm, post-endovascular treatment aorta, portal vein thrombosis, abdominal vascular trauma, and organ transplantation along with its complications.

Contrast-enhanced ultrasound (CEUS) in abdominal intervention.

The introduction of ultrasound contrast agents has rendered contrast-enhanced ultrasound (CEUS) a valuable complementary technique to address clinically significant problems. This pictorial review describes the use of CEUS guidance in abdominal intervention and illustrates such application for a range of clinical indications. Clinical application of CEUS discussed include commonly performed abdominal interventional procedures, such as biopsy, drainage, nephrostomy, biliary intervention, abdominal tumor ablation and its subsequent monitoring, and imaging of vascular complications following abdominal intervention. The purpose of this article is to further familiarize readers with the application of CEUS, particularly its specific strength over alternative imaging modalities, in abdominal intervention.