Shear-wave versus strain elastography in endoscopic ultrasound for the diagnosis of chronic pancreatitis

[Endo-Hepatology: New Endoscopic Solutions for Old Hepatological Problems]

With the rapid development of endoscopic ultrasound (EUS), diagnostic and therapeutic platforms have emerged that are applicable in hepatology. New tools such as EUS-guided portal pressure measurement (in combination with EUS-guided liver biopsy) or EUS-guided variceal obliteration using coils and glue present attractive procedures that can potentially overcome the limitations of current gold standards. In this review article, we provide an overview of these new 'endo-hepatology' techniques and highlight their current role in the treatment of liver diseases.

Advances in Endo-Hepatology: The Role of Endoscopic Ultrasound in the Management of Portal Hypertension

Portal hypertension (PH) is a complication of advanced liver diseases, including cirrhosis and hepatocellular carcinoma, often leading to unfavorable outcomes. Endo-hepatology, particularly endoscopic ultrasound (EUS) has revolutionized the assessment of PH. Notably, EUS-guided portal pressure gradient (EUS-PPG) enables measurement of portal and hepatic venous pressures, offering diagnostic precision for both cirrhotic and non-cirrhotic forms of PH, including porto-sinusoidal vascular disorder (PSVD). EUS-based assessment of PH in advanced liver disease can refine diagnostic workup and prognostication, supporting therapeutic decisions. Additionally, EUS-guided liver biopsy (EUS-LB) achieves high-quality histological samples with fewer complications compared to percutaneous techniques, enabling thorough evaluation of chronic liver diseases and vascular abnormalities. EUS-shear wave elastography (EUS-SWE) further refines stiffness measurements where standard imaging fails. Moreover, EUS plays a major role in controlling variceal hemorrhage, a severe PH complication. EUS-guided coil and cyanoacrylate injection for gastric varices demonstrate a great efficacy, often surpassing conventional endoscopy. Similarly, EUS-based identification and treatment of perforator vessels feeding esophageal varices reduce rebleeding risks, particularly in challenging patients. The combination of these state-of-the-art interventions supports a "one-stop strategy", integrating variceal screening, biopsy, and portal pressure measurement within a single procedure. Despite these advancements, refinements in sedation protocols, patient selection, and cost-effectiveness data are necessary. While noninvasive tools remain central in guidelines, EUS-based methods continue to expand their role, especially in complex cases. This review summarizes the applications and impact of EUS in evaluating PH, emphasizing its importance in contemporary hepatology and its potential as a pivotal diagnostic modality in cirrhosis complicated by PH.

The Role of Endoscopic Ultrasound-Guided Shear Wave Elastography in Pancreatic Diseases

Elastography is a non-invasive imaging modality that has been developed for the evaluation of the stiffness of various organs. It is categorized into two main types: strain elastography and shear wave elastography. While strain elastography offers valuable information on the mechanical properties of the organ being studied, it is limited by the qualitative nature of its measurements and its reliance on operator skills. On the other hand, shear wave elastography overcomes these limitations as it provides a quantitative assessment of tissue stiffness, offers more reproducibility, and is less operator-dependent. Endoscopic ultrasound-guided shear wave elastography (EUS-SWE) is an emerging technique that overcomes the limitations of transabdominal ultrasound in the evaluation of the pancreas. A growing body of literature has demonstrated its safety and feasibility in the evaluation of pancreatic parenchyma. This article provides a comprehensive review of the current state of the literature on EUS-SWE, including its technical aspects, clinical applications in the evaluation of various pancreatic conditions, technological limitations, and future directions.

Ultrasonographic Assessment of Tissue Stiffness: Recent Progress in Transient Elastography and Shear Wave Elastography in the Liver and Various Organs

Ultrasonography is a noninvasive and widely accessible modality in clinical practice. Recently, ultrasonography has been used to evaluate tissue stiffness; the two representative techniques are transient elastography (FibroScan®) and shear wave elastography. These modalities are now generally used for the assessment of liver fibrosis, the prediction of hepatocarcinogenesis, and determining prognosis. In addition, shear wave elastography is available, not only for the liver but also for various other organs, including the breast and brain. In the breast and brain, shear wave elastography distinguishes malignant lesions from benign ones. Moreover, shear wave elastography can be useful for differentiating between ischemic and hemorrhagic strokes. This review summarizes the recent progress in transient elastography and shear wave elastography of the liver and introduces the advantages of ultrasonographic assessment of tissue stiffness in various organs, including the breast, brain, kidney, heart, thyroid, pancreas, muscle, and bone.

Ultrasonic surface acoustic wave elastography: A review of basic theories, technical developments, and medical applications

Physiological and pathological changes in tissues often cause changes in tissue mechanical properties, making tissue elastography an effective modality in medical imaging. Among the existing elastography methods, ultrasound elastography is of great interest due to the inherent advantages of ultrasound imaging technology, such as low cost, portability, safety, and wide availability. However, most current ultrasound elastography methods are based on the bulk shear wave; they can image deep tissues but cannot image superficial tissues. To address this challenge, ultrasonic elastography methods based on surface acoustic waves have been proposed. In this paper, we present a comprehensive review of ultrasound-based surface acoustic wave elastography techniques, including their theoretical foundations, technical implementations, and existing medical applications. The goal is to provide a concise summary of the state-of-the-art of this field, hoping to offer a reliable reference for the further development of these techniques and foster the expansion of their medical applications.

Endoscopic procedures in hepatology: Current trends and new developments

Gastrointestinal endoscopy has long been a reliable backbone in the diagnosis and management of hepatobilary disorders and their complications. However, with evolving non-invasive testing, personalised medicine has reframed the utility and necessity of endoscopic screening. Conversely, the growing interest and use of endoscopic ultrasound (EUS) and advanced endoscopy within gastrointestinal units has also opened novel diagnostic and therapeutic avenues for patients with various hepatobiliary diseases. The integration of "advanced endoscopy" within the practice of hepatology is nowadays referred to as "endo-hepatology". In essence, endo-hepatology consists of two pillars: one focusing primarily on disorders of the liver parenchyma, vascular disorders, and portal hypertension, which is mainly captured via EUS, while the other targets the hepatobiliary tract via endoscopic retrograde cholangiopancreatography and advanced imaging. Applications under the umbrella of endo-hepatology include, amongst others, EUS-guided liver biopsy, EUS-guided portal pressure gradient measurement, coil and glue embolisation of gastric varices as well as cholangioscopy. As such endo-hepatology could become an attractive concept wherein advanced endoscopy might reinforce the medical management of patients with hepatobiliary disorders and their complications after initial basic work-up. In this review, we discuss current trends and future developments within endo-hepatology and the remaining hurdles to overcome.

Endoscopic Ultrasound (EUS) Guided Elastography

Endoscopic ultrasound (EUS) is an essential technique for the management of several diseases. Over the years, new technologies have been developed to improve and overcome certain limitations related to EUS-guided tissue acquisition. Among these new methods, EUS-guided elastography, which is a real-time method for the evaluation of tissue stiffness, has arisen as one of the most widely recognized and available. At present, there are available two different systems to perform an elastographic evaluation: strain elastography and shear wave elastography. Strain elastography is based on the knowledge that certain diseases lead to a change in tissue hardness while shear wave elastography monitored shear-wave propagation and measures its velocity. EUS-guided elastography has shown in several studies high accuracy in differentiating benign from malignant lesions from many different locations, mostly in the pancreas and lymph nodes. Therefore, nowadays, there are well-established indications for this technology, mainly for supporting the management of pancreatic diseases (diagnosis of chronic pancreatitis and differential diagnosis of solid pancreatic tumors) and characterization of different diseases. However, there are more data on new potential indications for the near future. In this review, we will present the theoretical bases of this technology and we will discuss the scientific evidence to support its use.