The technical part of these Guidelines and Recommendations, produced under the auspices of EFSUMB, provides an introduction to the physical principles and technology on which all forms of current commercially available ultrasound elastography are based. A difference in shear modulus is the common underlying physical mechanism that provides tissue contrast in all elastograms. The relationship between the alternative technologies is considered in terms of the method used to take advantage of this. The practical advantages and disadvantages associated with each of the techniques are described, and guidance is provided on optimisation of scanning technique, image display, image interpretation and some of the known image artefacts.

The clinical part of these Guidelines and Recommendations produced under the auspices of the European Federation of Societies for Ultrasound in Medicine and Biology EFSUMB assesses the clinically used applications of all forms of elastography, stressing the evidence from meta-analyses and giving practical advice for their uses and interpretation. Diffuse liver disease forms the largest section, reflecting the wide experience with transient and shear wave elastography . Then follow the breast, thyroid, gastro-intestinal tract, endoscopic elastography, the prostate and the musculo-skeletal system using strain and shear wave elastography as appropriate. The document is intended to form a reference and to guide clinical users in a practical way.

This manuscript describes the use of ultrasound elastography, with the exception of liver applications, and represents an update of the 2013 EFSUMB (European Federation of Societies for Ultrasound in Medicine and Biology) Guidelines and Recommendations on the clinical use of elastography.

MAIN RECOMMENDATIONSFor pancreatic solid lesions, ESGE recommends performing endoscopic ultrasound (EUS)-guided sampling as first-line procedure when a pathological diagnosis is required. Alternatively, percutaneous sampling may be considered in metastatic disease.Strong recommendation, moderate quality evidence.In the case of negative or inconclusive results and a high degree of suspicion of malignant disease, ESGE suggests re-evaluating the pathology slides, repeating EUS-guided sampling, or surgery.Weak recommendation, low quality evidence.In patients with chronic pancreatitis associated with a pancreatic mass, EUS-guided sampling results that do not confirm cancer should be interpreted with caution.Strong recommendation, low quality evidence.For pancreatic cystic lesions (PCLs), ESGE recommends EUS-guided sampling for biochemical analyses plus cytopathological examination if a precise diagnosis may change patient management, except for lesions ≤ 10 mm in diameter with no high risk stigmata. If the volume of PCL aspirate is small, it is recommended that carcinoembryonic antigen (CEA) level determination be done as the first analysis.Strong recommendation, low quality evidence.For esophageal cancer, ESGE suggests performing EUS-guided sampling for the assessment of regional lymph nodes (LNs) in T1 (and, depending on local treatment policy, T2) adenocarcinoma and of lesions suspicious for metastasis such as distant LNs, left liver lobe lesions, and suspected peritoneal carcinomatosis.Weak recommendation, low quality evidence.For lymphadenopathy of unknown origin, ESGE recommends performing EUS-guided (or alternatively endobronchial ultrasound [EBUS]-guided) sampling if the pathological result is likely to affect patient management and no superficial lymphadenopathy is easily accessible.Strong recommendation, moderate quality evidence.In the case of solid liver masses suspicious for metastasis, ESGE suggests performing EUS-guided sampling if the pathological result is likely to affect patient management, and (i) the lesion is poorly accessible/not detected at percutaneous imaging, or (ii) a sample obtained via the percutaneous route repeatedly yielded an inconclusive result.Weak recommendation, low quality evidence.

Tissue stiffness assessed by palpation for diagnosing pathology has been used for thousands of years. Ultrasound elastography has been developed more recently to display similar information on tissue stiffness as an image. There are two main types of ultrasound elastography, strain and shear wave. Strain elastography is a qualitative technique and provides information on the relative stiffness between one tissue and another. Shear wave elastography is a quantitative method and provides an estimated value of the tissue stiffness that can be expressed in either the shear wave speed through the tissues in meters/second, or converted to the Young’s modulus making some assumptions and expressed in kPa. Each technique has its advantages and disadvantages and they are often complimentary to each other in clinical practice. This article reviews the principles, technique, and interpretation of strain elastography in various organs. It describes how to optimize technique, while pitfalls and artifacts are also discussed.

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This is the first part of the Guidelines on Interventional Ultrasound of the European Federation of Societies for Ultrasound in Medicine and Biology (EFSUMB) and covers all general aspects of ultrasound-guided procedures (long version).

The value of quantitative analysis of EUS elastography recordings was proven by good reproducibility of the videos, as well as good parameters of the AUROC analysis. (Clinical Trials.gov identifier: CT00909103).