Endoscopic ultrasound of the upper gastrointestinal tract

Endoscopic ultrasound (EUS) is an evolving technique used by gastroenterologists to examine lesions that are located either within or adjacent to the walls of the upper gastrointestinal (GI) tract; this topic is relatively unknown to most radiologists. Proper use of this modality is benefited by a cooperative effort between gastroenterologists and radiologists specializing in ultrasound and cross-sectional imaging. This article informs radiologists of the applications of this procedure. Most patients are examined with EUS after a biopsy of a mucosal tumor has been performed. A smaller number are performed to evaluate submucosal masses or when pancreatic disease is suspected but not diagnosed. The examinations can be performed either with dedicated flexible echoendoscopes or with catheter-based probes passed through a conventional endoscope. The exact location of abnormalities associated with the upper GI tract can be observed. Known anatomic landmarks are sought. Abnormalities of structures outside the upper GI tract will occasionally be found during these examinations. The specific layers of the walls of the gut are examined, and the T and N-classification of upper GI tumors can be determined accurately. The performance of an EUS examination requires advanced skills, and in many medical centers, it is the imaging modality of choice to stage cancers, to evaluate submucosal masses, and to investigate both malignant and benign pancreaticobiliary disease. Endoscopic ultrasound is sensitive but not specific, and biopsy is necessary to establish a diagnosis. Therapeutic applications of EUS are evolving. Specialized applications with catheter-based probes are also being developed.     

Endoscopic ultrasound for luminal malignancies

Luminal gastrointestinal (GI) tract cancers are responsible for substantial morbidity and mortality. Since the first pairing of ultrasonography with endoscopy in 1980, technologic advances and the increased availability of trained endosonographers have propelled endoscopic ultrasonography (EUS) to the forefront of luminal GI cancer staging. In this article we discuss the role of EUS for evaluating luminal GI cancers.     

Ultrasound Capsule Endoscopy With a Mechanically Scanning Micro-ultrasound: A Porcine Study

Wireless capsule endoscopy has been used for the clinical examination of the gastrointestinal (GI) tract for two decades. However, most commercially available devices only utilise optical imaging to examine the GI wall surface. Using this sensing modality, pathology within the GI wall cannot be detected. Micro-ultrasound (μUS) using high-frequency (>20 MHz) ultrasound can provide a means of transmural or cross-sectional image of the GI tract. Depth of imaging is approximately 10 mm with a resolution of between 40–120 μm that is sufficient to differentiate between subsurface histologic layers of the various regions of the GI tract. Ultrasound capsule endoscopy (USCE) uses a capsule equipped with μUS transducers that are capable of imaging below the GI wall surface, offering thereby a complementary sensing technique to optical imaging capsule endoscopy. In this work, a USCE device integrated with a ∼30 MHz ultrasonic transducer was developed to capture a full 360° image of the lumen. The performance of the device was initially evaluated using a wire phantom, indicating an axial resolution of 69.0 μm and lateral resolution of 262.5 μm. Later, in vivo imaging performance was characterised in the oesophagus and small intestine of anaesthetized pigs. The reconstructed images demonstrate clear layer differentiation of the lumen wall. The tissue thicknesses measured from the B-scan images show good agreement with ex vivo images from the literature. The high-resolution ultrasound images in the in vivo porcine model achieved with this device is an encouraging preliminary step in the translation of these devices toward future clinical use.     

超声内镜对上消化道隆起病灶的诊断价值

本文报告超声内镜（ＥＵＳ）对１７８例上消化道隆起性病灶的诊断与鉴别诊断，并与胃镜、钡餐造影和ＣＴ进行比较。     

Advances in the endoscopic management of patients with pancreatic and biliary malignancies

Major advances in endoscopic techniques to diagnose and manage pancreatic biliary diseases have fundamentally changed the approach to these difficult clinical challenges. The diagnosis of benign and malignant pancreatic-biliary diseases is much more readily obtained through a combination of cross-sectional imaging and endoscopic procedures. Endoscopic retrograde cholangiopancreatography (ERCP) and endoscopic ultrasound (EUS) are the most important endoscopic tools for imaging and accessing the pancreatic biliary system. The review summarizes the major imaging methods for providing a diagnosis of bile duct malignancy, including ERCP, transhepatic cholangiography (THC), and magnetic resonance cholangiopancreatography (MRCP). High quality image examples of cholangiocarcinoma are provided. EUS has provided a new imaging modality for the detection of pancreatic and biliary malignancy. EUS is particularly sensitive for the detection of early pancreatic malignancy. Furthermore, EUS excels at the guidance of fine needle aspiration of pancreatic lesions. Diagnostic tissue acquisition for cholangiocarcinoma remains an important challenge. The endoscopic therapy for pancreatic-biliary malignancy involves the use of stenting which relieves the biliary obstruction commonly seen in these patients.     

内镜超声弹性成像的原理与临床应用

内镜超声（endoscopic ultrasound, EUS）已成为消化系统疾病的重要诊断手段之一。内镜超声弹性成像（EUS Elastography, EUS E）能够实现胃肠道及其毗邻器官的可视化弹性评估,提高了EUS对消化道疾病诊断能力。此外,EUS E还可为内镜超声引导下细针穿刺（EUS fine needle aspiration, EUS FNA）技术提供辅助信息,从而提高疾病诊断和组织学获取的准确性。本文主要就EUS E的原理、方法和临床应用作一综述。     

Subepithelial masses of the gastrointestinal tract evaluated by endoscopic ultrasonography.

OBJECTIVES: To diagnose and characterize subepithelial lesions of the gastrointestinal (GI) tract using endoscopic ultrasonography (EUS) and search for markers of malignancy in stromal cell tumors. METHODS: Fifty-four patients with suspected subepithelial lesions at endoscopy were examined using miniature ultrasound probes, integrated ultrasound endoscopes, or both. Surgical treatment was considered if a solid lesion had a maximum diameter of at least 3 cm, mixed echogenicity, or an ill-defined or irregular border. RESULTS: EUS disclosed 37 solid lesions and ten fluid-filled structures. In seven patients, including two with protrusion from a normal spleen, no pathology could be demonstrated. Thirteen patients were operated and 41 were observed clinically with (n = 9) or without EUS (n = 32) for a median follow-up period of 36 months. Twenty-three patients had an intramural stromal cell tumor. None of these were malignant, but increased mitotic activity was found in two medium-sized resected tumors with mixed echogenicity and bleeding lesions of the endoluminal surface. CONCLUSION: EUS can detect and characterize subepithelial masses in the GI tract. Pathologic lesions of the overlying mucosa may indicate malignant development in stromal cell tumors, but valid markers of malignant potential are still lacking.     

超声内镜对胆道占位性病变的诊断价值

胆道占位性病变是引起梗阻性黄疸的主要原因,但由于其位置特殊,传统的影像学诊断较为困难,超声内镜（EUS）利用消化道自然腔道,有效避开腹壁脂肪和肠道气体的干扰,使胆道系统呈现清晰的显像;尤其是近年来开展的EUS引导下的细针穿刺、造影增强超声内镜对胆道占位性病变有较高的诊断价值,在其鉴别诊断方面也发挥着越来越重要的作用。     

Role of endoscopic ultrasound in the diagnosis and staging of pancreatic cancer

Early diagnosis of pancreatic cancer remains a difficult task, and multiple imaging tests have been proposed over the years. The aim of this review is to describe the current role of endoscopic ultrasound (EUS) for the diagnosis and staging of patients with pancreatic cancer. A detailed search of MEDLINE between 1980 and 2007 was performed using the following keywords: pancreatic cancer, endoscopic ultrasound, diagnosis, and staging. References of the selected articles were also browsed and consulted. Despite progress made with other imaging methods, EUS is still considered to be superior for the detection of clinically suspected lesions, especially if the results of other cross-sectional imaging modalities are equivocal. The major advantage of EUS is the high negative predictive value that approaches 100%, indicating that the absence of a focal mass reliably excludes pancreatic cancer. The introduction of EUS-guided fine needle aspiration allows a preoperative diagnosis in patients with resectable cancer, as well as a confirmation of diagnosis before chemoradiotherapy for those that are not. This comprehensive review highlighted the diagnostic capabilities of EUS including the newest refinements such as contrast-enhanced EUS, EUS elastography, and 3-dimensional EUS. The place of EUS-guided biopsy is also emphasized, including the addition of molecular marker techniques.     

A new technique in endoscopic ultrasonography of the upper gastrointestinal tract

Endoscopic ultrasonography (EUS) of the upper GI tract was unsuccessful in 42 out of 274 patients (15%) due to inaccurate guidance of the probe to small, shallow lesions, or to difficulty in clearly demonstrating the surrounding layer structure and boundary of the lesion. We applied the saline injection technique in these 42 patients. Saline was injected into the submucosal layer of the esophagogastric wall. The ultrasonographic image of adjacent saline accurately guided the probe to the lesion. Injected saline enabled the mucosal layer to be distinguished from the muscularis propria surrounding the lesion and provided clear ultrasonographic imaging of the boundary between the lesion and the surrounding layer structure. This new method was found to be effective in 38 out of 42 patients in whom EUS was unsuccessful. A study comparing the depth of tumor invasion diagnosed by the saline injection technique with histological findings obtained in 12 cases showed good correlation. These results indicate that the saline injection technique would seem to be very useful as an adjuvant to conventional EUS.     

Endosonography in decision making and management of gastrointestinal endocrine tumors.

OBJECTIVE: gastroenteropancreatic (GEP) neuroendocrine tumors, suspected on clinical basis, are often difficult to localize. We report our experience with endoscopic ultrasonography (EUS) in the preoperative localization of pancreatic endocrine tumors (PETs), compared to other imaging modalities, and in staging and following up carcinoid tumors (CTs) of the gastrointestinal (GI) wall. METHODS: 50 patients (20 males; mean age 54 years), 39 with suspected PETs and 11 with GI CTs underwent EUS (Olympus GF-UM2 or GF-UM3). EUS data could be compared with resected specimens in 25 out of the 39 PETs and five out of the 11 CTs. RESULTS: in the PETs group 42 tumors (35<20 mm) were removed: 23 in the pancreas, eight in the duodenum, and 11 in the lymph nodes. EUS correctly localized 20 out of the 23 (87%) pancreatic tumors, included 11 out of the 12 (91.6%) insulinomas, three out of the eight (37.5%) duodenal gastrinomas, and ten out of the 11 (90.9%) metastatic lymph nodes. Furthermore EUS accurately evaluated the depth of parietal invasion of CTs in three out of four patients (75%) (two after and one prior to endoscopic resection). In three patients EUS was confirmed as normal on resected specimens (two pancreas and one stomach). In the PETs group, a correct localization was obtained by ultrasonography (US) only in 17.4% of cases, by computed tomography (CT) in 30.4%, by magnetic resonance imaging (MRI) in 25%, by angiography in 26.6%, and by somatostatin receptor scintigraphy in 15.4%. CONCLUSION: EUS must be considered the first-intention method in localizing PETs and is helpful in decision making and management of GEP endocrine tumors.     

The role of endosonography in the diagnosis of choledocholithiasis.

Biliary endoscopic ultrasonography (EUS), even if complex and difficult to interpret, can depict with great accuracy the normal anatomy and abnormalities of this region. In case of choledocholithiasis, EUS has the unique ability to directly visualize the cause of biliary obstruction and to evaluate and integrate ductal abnormalities. For these tasks EUS is superior to conventional ultrasonography (US), computed tomography (CT) and also to new imaging techniques such as magnetic resonance cholangiography. The aim of this review is to provide an overview of the most significant EUS findings in choledocholithiasis together with the results of EUS in terms of diagnostic accuracy and cost-effectiveness. The role of EUS in the diagnosis of bile duct stones is therefore highlighted.     

超声内镜对十二指肠隆起病灶的诊断价值

该文采用超声内镜、内镜、X线钡餐造影和CT比较研究法,评价66例EUS诊断十二指肠隆起病灶的价值。结果:66例十二指肠隆起性病灶的发生率依次为壶腹癌、壁外肿瘤压迫、壁外脏器压迫、粘膜下肿瘤、息肉、乳头炎、十二指肠癌、鲍氏腺瘤、淋巴瘤。对十二指肠隆起病灶的总诊断符合率EUS为93.94％,明显高于内镜(75.76％)和钡餐造影(53.03％)。EUS对息肉、鲍氏腺瘤、乳头炎的诊断符合率低于内镜,对壶腹癌、十二指肠癌、淋巴瘤的诊断符合率则与内镜相当。EUS系目前确诊十二指肠粘膜下肿瘤及壁外压迫病灶的最佳方法。结论:该资料显示EUS诊断十二指肠隆起性病灶具有较高的价值。     

Nongynecologic findings on pelvic ultrasound: focus on gastrointestinal diseases

Ultrasound (US) is considered the first-line imaging modality of choice in women presenting with pelvic complaints. Although imaging is focused on detecting abnormalities of the uterus and adnexa, occasionally nongynecologic findings are detected, which may or may not explain the patient's symptoms. Many of these findings are related to the gastrointestinal (GI) tract. Although most of these GI abnormalities are better diagnosed with computed tomography (CT), symptoms are often nonspecific and US may be the first imaging modality requested by referring clinicians. Sonographers should be aware of the possibility of nongynecologic diseases in patients with pelvic symptoms, particularly if US evaluation of the female reproductive tract does not provide an answer to the clinical question. Careful attention to the bowel when performing a pelvic US may allow the sonographer to diagnose GI pelvic diseases such as appendicitis, diverticulitis, colitis, bowel obstruction, mesenteric adenitis, epiploic appendagitis, Crohn disease, and even GI malignancy. As concerns grow regarding the radiation dose of pelvic CT, the use of iodinated contrast material, and imaging costs, US examination may be increasingly requested as an initial imaging study in patients in whom GI diseases is primarily suspected in the pelvis, and familiarity with the various sonographic manifestations will aid considerably in establishing the correct diagnosis.     

Endoscopic ultrasonography in the diagnosis and management of cancer

Since its development and introduction to clinical practice, endoscopic ultrasonography (EUS) has progressed rapidly from being a purely imaging modality with limited use in the detection of small pancreatic cancers to one that can provide a tissue diagnosis by fine-needle aspiration (FNA) and deliver therapy. EUS has now firmly established a place as the investigation of choice in the diagnosis, locoregional staging and management of a wide range of gastrointestinal cancers. With the increasing use of FNA, the accuracy of EUS has substantially improved and may become a stand-alone investigation in some situations. However, it is recommended that a combination of information obtained from other imaging modalities and EUS is needed to maximize the accuracy, in particular to complete staging beyond locoregional stage. In addition to well-established indications, newer applications of EUS are emerging and are no longer limited to the gastrointestinal system. In lung cancer, EUS combined with endobronchial ultrasonography is emerging as an accurate, minimally invasive, nonsurgical alternative to staging of the mediastinum. Furthermore, the ability of EUS to acquire tissue safely and conveniently results in a potential role of the molecular diagnostics to enhance the performance of EUS-guided FNA. Besides a diagnostic role of EUS, there continues to be technological advances in the field of interventional EUS, with many potential applications under investigation. This review focuses on the current and future roles of EUS in the diagnosis and management of cancers.     

Ureteral metastasis from an appendiceal carcinoma and diagnosis by endoscopic ultrasound-guided fine-needle aspiration

Endoscopic ultrasound (EUS) is a standard tool for imaging the gastrointestinal tract and adjacent structures. EUS-guided fine-needle aspiration (FNA) allows the endosonographer easy access to these structures for both diagnostic and therapeutic purposes. We describe a case of metastatic lesion, adherent to a stented right ureter, which was imaged with transrectal EUS, with successful cytologic identification after EUS-guided FNA. EUS and EUS-guided FNA can be valuable tools in the evaluation of some soft-tissue abnormalities of the pelvis.     

The role of endoscopic ultrasound in inflammatory bowel disease

Ultrasonography has been applied to the diagnosis and management of inflammatory bowel disease for over 20 years. The combination of endoscopy with ultrasound has resulted in the application of intraluminal sonographic imaging to multiple diseases, including inflammatory bowel disease. Initial efforts were focused on the sonographic assessment of disease severity as based on bowel wall thickness, but this has been inconsistently demonstrated. Furthermore, disease severity is a clinical assessment that is based on both clinical and imaging studies. Recognizing that Crohn's disease tends to be transmural and ulcerative colitis a superficial mucosal inflammatory process, hopes were raised that endosonography would be effective in discriminating cases of otherwise indeterminate colitis. Efforts to demonstrate this, however, have been largely disappointing, and EUS plays a limited role in discriminating ulcerative colitis from Crohn's disease. On a more positive note, EUS evaluation of perirectal and perianal complications of Crohn's disease has been demonstrated to be superior to fistulography, CT, and equal to or superior to MRI. Because accurate anatomic information is required to guide surgical therapy of these lesions, EUS has the potential to emerge as a powerful imaging tool in the management of perianorectal Crohn's disease.     

Endoscopic ultrasonography.

Over the past two decades, endoscopic ultrasonography (EUS) has undergone a transition from being a novel imaging technique to a clinical diagnostic test that is necessary for the optimal management of gastrointestinal diseases. EUS has established itself as an important diagnostic modality, mainly for the detection and staging of gastrointestinal cancers. As EUS has become more widespread, research has gradually shifted towards studies that explore the effect of EUS on patient management and outcome. These outcome studies have examined the primary clinical applications of EUS, such as esophageal, gastric, pancreatic, and colorectal cancer staging, as well as the role of EUS in the diagnosis of inflammatory pancreatic diseases. Widespread use of EUS has recently led to studies that examine complications associated with the performance of the procedure. Endosonographers have continued efforts to define a clinical role for EUS in other gastrointestinal diseases, such as portal hypertension. EUS-guided fine-needle aspiration (FNA) is continuing to develop into a powerful diagnostic tool for the management of lung cancer and other mediastinal diseases. New applications for EUS-FNA are also emerging. Finally, investigators are continuing to explore the remaining frontier of EUS-guided therapy.     

The Wnt agonist R-spondin1 regulates systemic graft-versus-host disease by protecting intestinal stem cells

Graft-versus-host disease (GVHD) is a major complication of allogeneic bone marrow transplantation (BMT), and damage to the gastrointestinal (GI) tract plays a critical role in amplifying systemic disease. Intestinal stem cells (ISCs) play a pivotal role not only in physiological tissue renewal but also in regeneration of the intestinal epithelium after injury. In this study, we have discovered that pretransplant conditioning regimen damaged ISCs; however, the ISCs rapidly recovered and restored the normal architecture of the intestine. ISCs are targets of GVHD, and this process of ISC recovery was markedly inhibited with the development of GVHD. Injection of Wnt agonist R-spondin1 (R-Spo1) protected against ISC damage, enhanced restoration of injured intestinal epithelium, and inhibited subsequent inflammatory cytokine cascades. R-Spo1 ameliorated systemic GVHD after allogeneic BMT by a mechanism dependent on repair of conditioning-induced GI tract injury. Our results demonstrate for the first time that ISC damage plays a central role in amplifying systemic GVHD; therefore, we propose ISC protection by R-Spo1 as a novel strategy to improve the outcome of allogeneic BMT.     

Common laboratory and diagnostic testing in patients with gastrointestinal disease

Evaluating patients with gastrointestinal (GI) illness involves the use of many different diagnostic modalities, including laboratory studies, diagnostic imaging, and endoscopy. Rapid advances in all three areas have provided clinicians with a wide array of testing at their fingertips. The frequent challenge in evaluating a patient is deciding which testing will lead to a diagnosis in the most direct and efficient manner. This article reviews many of the tests that are considered in the evaluation of individuals with complaints referable to the GI tract.