Dagmar Schreiber-Dietrich

Pitfalls and Artefacts using Contrast Enhanced Ultrasound

Ultrasound is the method of choice in the detection and characterization of diffuse and focal organic diseases. For B-mode and colour (power) Doppler ultrasound, besides manual skills, (hands-on) a technical knowledge about ultrasound images is of the upmost importance for the investigator. Contrast enhanced ultrasound (CEUS) has become an important diagnostic tool for hepatic, renal, pancreatic indications and several others due to: (a) an increasing rate of studies resulting in sufficient evidence especially in hepatic indications, (b) a rate of adverse events close to zero (1:10,000 in comparison to iodinated contrast agents from 1-12:100) enabling the application of CEUS in patients with severe renal insufficiency or thyroid gland autonomy, and (c) a reasonable price (depends on the country and influence of the health-care system [reimbursement]) and the dosage used. Mini-doses from 0.1 to 0.4 mL are used depending on the contrast agent and applied indication. Therefore a well founded knowledge concerning the technical aspects of CEUS is important for the investigator to avoid misinterpretation especially when artefacts specific for CEUS occur. Special literature is rare. In the presented article we present pitfalls concerning CEUS. The following aspects are considered and illustrated by images: (i) acoustic power (mechanical index) and other aspects resulting in micro bubble destruction, (ii) the possibility of false positive contrast signals in non-vascularized areas, (iii) attenuation caused by too high contrast agent dose, (iv) influence of the frame rate on the spatial resolution, (v) dealing with deep located lesions, (vi) differences in focus positioning in detection and characterization studies, (vii) advantages and disadvantages of replenishment studies, (viii) reliability of contrast enhanced spectral Doppler measurements.

Liver elastography, comments on EFSUMB elastography guidelines 2013

Recently the European Federation of Societies for Ultrasound in Medicine and Biology Guidelines and Recommendations have been published assessing the clinical use of ultrasound elastography. The document is intended to form a reference and to guide clinical users in a practical way. They give practical advice for the use and interpretation. Liver disease forms the largest section, reflecting published experience to date including evidence from meta-analyses with shear wave and strain elastography. In this review comments and illustrations on the guidelines are given.

Fortuitously discovered liver lesions

The fortuitously discovered liver lesion is a common problem. Consensus might be expected in terms of its work-up, and yet there is none. This stems in part from the fact that there is no preventive campaign involving the early detection of liver tumors other than for patients with known liver cirrhosis and oncological patients. The work-up (detection and differential diagnosis) of liver tumors comprises theoretical considerations, history, physical examination, laboratory tests, standard ultrasound, Doppler ultrasound techniques, contrast-enhanced ultrasound (CEUS), computed tomography and magnetic resonance imaging, as well as image-guided biopsy. CEUS techniques have proved to be the most pertinent method; these techniques became part of the clinical routine about 10 years ago in Europe and Asia and are used for a variety of indications in daily clinical practice. CEUS is in many cases the first and also decisive technical intervention for detecting and characterizing liver tumors. This development is reflected in many CEUS guidelines, e.g., in the European Federation of Societies for Ultrasound in Medicine and Biology (EFSUMB) guidelines 2004, 2008 and 2012 as well as the recently published World Federation for Ultrasound in Medicine and Biology-EFSUMB guidelines 2012. This article sets out considerations for making a structured work-up of incidental liver tumors feasible.

Dynamic contrast-enhanced ultrasound for quantification of tissue perfusion.

Dynamic contrast‐enhanced ultrasound (US) imaging, a technique that uses microbubble contrast agents with diagnostic US, has recently been technically summarized and reviewed by a European Federation of Societies for Ultrasound in Medicine and Biology position paper. However, the practical applications of this imaging technique were not included. This article reviews and discusses the published literature on the clinical use of dynamic contrast‐enhanced US. This review finds that dynamic contrast‐enhanced US imaging is the most sensitive cross‐sectional real‐time method for measuring the perfusion of parenchymatous organs noninvasively. It can measure parenchymal perfusion and therefore can differentiate between benign and malignant tumors. The most important routine clinical role of dynamic contrast‐enhanced US is the prediction of tumor responses to chemotherapy within a very short time, shorter than using Response Evaluation Criteria in Solid Tumors criteria. Other applications found include quantifying the hepatic transit time, diabetic kidneys, transplant grafts, and Crohn disease. In addition, the problems involved in using dynamic contrast‐enhanced US are discussed.

Benign liver tumors in pediatric patients - Review with emphasis on imaging features

Benign hepatic tumors are commonly observed in adults, but rarely reported in children. The reasons for this remain speculative and the exact data concerning the incidence of these lesions are lacking. Benign hepatic tumors represent a diverse group of epithelial and mesenchymal tumors. In pediatric patients, most benign focal liver lesions are inborn and may grow like the rest of the body. Knowledge of pediatric liver diseases and their imaging appearances is essential in order to make an appropriate differential diagnosis. Selection of the appropriate imaging test is challenging, since it depends on a number of age-related factors. This paper will discuss the most frequently encountered benign liver tumors in children (infantile hepatic hemangioendothelioma, mesenchymal hamartoma, focal nodular hyperplasia, nodular regenerative hyperplasia, and hepatocellular adenoma), as well as a comparison to the current knowledge regarding such tumors in adult patients. The current emphasis is on imaging features, which are helpful not only for the initial diagnosis, but also for pre- and post-treatment evaluation and follow-up. In addition, future perspectives of contrast-enhanced ultrasound (CEUS) in pediatric patients are highlighted, with descriptions of enhancement patterns for each lesion being discussed. The role of advanced imaging tests such as CEUS and magnetic resonance imaging, which allow for non-invasive assessment of liver tumors, is of utmost importance in pediatric patients, especially when repeated imaging tests are needed and radiation exposure should be avoided.

Contrast enhanced ultrasound in pediatric patients: a real challenge.

Ultrasound (US) imaging in the paediatric population has been a routine technique for decades, in part because of the advantages it offers over other imaging modalities. Off-label use (and its funding) is of the utmost importance in paediatrics because many drugs have not been evaluated in randomised trials in children. As a consequence such drugs are not specifically approved for use in children. This is also true for the contrast agents used in CEUS. The off-label use of CEUS in paediatric patients illustrates the need to deal with unresolved legal issues while at the same time balancing this with the need for high diagnostic performance in daily clinical routine. In addition to approved indications with a focus on the liver and Doppler enhancement, CEUS is safe and effective for the examination of many organs, as recently highlighted by the European Federation of Societies for Ultrasound in Medicine and Biology (EFSUMB). This article provides a summary of the available literature describing the utility of CEUS in paediatric patients. Furthermore, we suggest the establishment of a registry to collect data on safety and applications of ultrasound contrast agents in children. A paediatric registry has recently been introduced by EFSUMB (www.efsumb.org).

Ultrasonographic imaging of inflammatory bowel disease in pediatric patients.

Inflammatory bowel disease (IBD) is one of the most common chronic gastrointestinal diseases in pediatric patients. Choosing the optimal imaging modality for the assessment of gastrointestinal disease in pediatric patients can be challenging. The invasiveness and patient acceptance, the radiation exposure and the quality performance of the diagnostic test need to be considered. By reviewing the literature regarding imaging in inflammatory bowel disease the value of ultrasound in the clinical management of pediatric patients is highlighted. Transabdominal ultrasound is a useful, noninvasive method for the initial diagnosis of IBD in children; it also provides guidance for therapeutic decisions and helps to characterize and predict the course of the disease in individual patients. Ultrasound techniques including color Doppler imaging and contrast-enhanced ultrasound are promising imaging tools to determine disease activity and complications. Comparative studies between different imaging methods are needed.

Sonografische Funktionsuntersuchungen in der Gastroenterologie

Ultrasonography has become increasingly important in the routine diagnostics of gastrointestinal diseases. It is first of all a morphological diagnostic method. As it not only assesses the wall structure of the gallbladder, the pancreatic duct and the whole gastrointestinal tract but also visualises motion sequences as a real-time-method, functional processes and their disruptions can especially be examined. The present authors give a review of the capacity of functional ultrasound in different anatomic zones and critically discuss its practical relevance.

Vascular phases in imaging and their role in focal liver lesions assessment

The incidental finding of a liver lesion with basic ultrasound is one of the most common clinical issues. Some of the liver lesions which present typical morphological B-mode features (e.g. cysts, typically localized focal fatty sparing/accumulations, hyperechoic hemangiomas) can be easily diagnosed by conventional ultrasound without the need of further diagnostic procedures. Others frequently necessitate further investigation with contrast-enhanced imaging techniques or biopsy in order to differentiate benign from malignant lesions and obtain a final diagnosis. This paper will discuss differences between vascular phases of different cross-sectional contrast-enhanced methods, as well as their subsequent benefits for focal liver lesions (FLLs) assessment, adding also a particular emphasis on small FLLs detection and characterization.

Particularities of Crohn’s disease in pediatric patients: current status and perspectives regarding imaging modalities

A consensus on the best imaging modality evaluating inflammatory bowel disease in the pediatric population is lacking and it is often unclear which modality to choose in specific clinical circumstances. Children with inflammatory bowel disease are exposed to ionizing radiation from multiple imaging studies performed at initial diagnosis, throughout treatment and during the follow-up period. This paper discusses the value of different imaging techniques in pediatric patients with inflammatory bowel disease and gives a review of the literature. In addition, particular features of inflammatory bowel disease in children including the predilection of affected segments in the gastrointestinal tract are highlighted. Based on current literature knowledge, we encourage an integrative approach to the interpretation of clinical and imaging data for diagnosis and follow-up in daily clinical settings.