Endoscopic ultrasound in the diagnosis, staging, and management of gastrointestinal and adjacent malignancies

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.

Quantitative Elastography Versus Fine-needle Aspiration by Endoscopic Ultrasound for the Assessment of Pancreatic Solid Masses

BACKGROUND AND AIMS

Pancreatic solid masses (PSM) are difficult to assess; endoscopic ultrasound with fine-needle aspiration (FNA) enables tissue acquisition, but has high false-negative rates. Quantitative elastography (QE) predicts diagnosis on the basis of the strain ratio (SR). We aimed to compare both methods to evaluate PSM.

MATERIALS AND METHODS

This prospective study, carried out between January and December 2016, included suspected PSM cases; those with advanced disease and cystic components were excluded. Both procedures were performed; histologic information was obtained for the final diagnoses. Diagnostic tests and receiver-operating characteristic curve were calculated. P<0.05 was considered statistically significant.

RESULTS

We included 134 patients (53% women; mean, 53±16.2 y). The median tumor size was 30 (10 to 78) mm, with 69.4% and 30.6% malignant and benign tumors (median SR: 19.5 vs. 7.5; P=0.000), respectively, and 87% were pancreatic adenocarcinoma. QE with SR cutoff ≥10 showed similar parameters to FNA in both PSM types: sensitivity, 94% in both; specificity, 85% versus 87%; positive predictive value, 93% versus 94%; negative predictive value, 87% in both; and accuracy, 92% for malignant and sensitivity, 85% versus 87%; specificity, 94% in both; positive predictive value, 87% in both; negative predictive value, 93% versus 94%; and accuracy, 92% for benign. The area under the curve was 0.96 (P<0.000; 95% confidence interval, 0.940-0.995). New classifications on the basis of positive likelihood ratio were grouped as follows: A ≤8.7 (benign tumor); B >8.7 to <15.5 (indeterminate); and C ≥15.5 (malignant).

CONCLUSIONS

QE has similar capacity to FNA in PSM evaluation. However, the former can be used potentially as a substitute of the latter in certain cases on the basis of these new SR cutoff-based classifications.

Anaplastic Thyroid Carcinoma with Gastric Metastasis

Introduction. Carcinomas of the thyroid gland represent 3% of all malignancies, with 1.3 to 9.8% corresponding to anaplastic thyroid carcinomas (ATC). Metastases are present in 50% of patients when ATC is diagnosed. Gastrointestinal metastases are a rare finding in patients with thyroid carcinoma. Case report. A 68-year old gentleman with a history of papillary thyroid carcinoma (PTC) underwent surgery and radiopharmaceutical therapy. Restaging studies nine months later suggested wall thickening localizing to the distal stomach. Endoscopy results showed a large, infiltrative, subepithelial, and ulcerated gastric mass and biopsies revealed anaplastic thyroid carcinoma Conclusion. Incidental thickening or other findings in the stomach in a patient with ATC without gastrointestinal symptoms should be further investigated with endoscopy and biopsies to rule out gastric metastases from anaplastic thyroid carcinoma.

New Imaging Techniques: Endoscopic Ultrasound-Guided Elastography

Endoscopic ultrasound (EUS) is a major imaging method in the management of several diseases of the gastrointestinal tract and surrounding structures. Elastography is a novel technique providing additional information to standard B-mode imaging on the tissue stiffness. Elastography can be performed under EUS guidance. This method has proven to be an accurate and additional tool in the evaluation of pancreatic diseases and lymph nodes analysis. Possible uses include the study of liver lesions, subepithelial masses, and many more. This article reviews current knowledge and future perspectives.

Endoscopic ultrasound elastography: Current status and future perspectives

Elastography is a new ultrasound modality that provides images and measurements related to tissue stiffness. Endoscopic ultrasound (EUS) has played an important role in the diagnosis and management of numerous abdominal and mediastinal diseases. Elastography by means of EUS examination can assess the elasticity of tumors in the proximity of the digestive tract that are hard to reach with conventional transcutaneous ultrasound probes, such as pancreatic masses and mediastinal or abdominal lymph nodes, thus improving the diagnostic yield of the procedure. Results from previous studies have promised benefits for EUS elastography in the differential diagnosis of lymph nodes, as well as for assessing masses with pancreatic or gastrointestinal (GI) tract locations. It is important to mention that EUS elastography is not considered a modality that can replace biopsy. However, it may be a useful adjunct, improving the accuracy of EUS-fine needle aspiration biopsy (EUS-FNAB) by selecting the most suspicious area to be targeted. Even more, it may be useful for guiding further clinical management when EUS-FNAB is negative or inconclusive. In the present paper we will discuss the current knowledge of EUS elastography, including the technical aspects, along with its applications in the differential diagnosis between benign and malignant solid pancreatic masses and lymph nodes, as well as its aid in the differentiation between normal pancreatic tissues and chronic pancreatitis. Moreover, the emergent indication and future perspectives are summarized, such as the benefit of EUS elastography in EUS-guided fine needle aspiration biopsy, and its uses for characterization of lesions in liver, biliary tract, adrenal glands and GI tract.

Role of endoscopic ultrasound in diagnosis and management of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is an aggressive tumor and a leading cause of cancer-related deaths globally. The mortality rate remains high despite many advances in treatment. HCC is frequently diagnosed late in its course due to lack of classical symptoms at earlier stages. Endoscopic ultrasound (EUS) has emerged as an important diagnostic tool for the diagnostic evaluation, staging, and treatment of gastrointestinal tract disorders. EUS-guided fine needle aspiration has been a valuable addition to EUS by being able to obtain tissue under direct visualization. Here, we review the potential role of EUS in the diagnosis and management of HCC. EUS seems to be a safe and reliable alternative method for obtaining tissue for diagnosis of liver cancer, especially for lesions that are inaccessible by traditional methods. EUS could play an important role in the diagnosis and management of HCC.

Endoscopic ultrasound: Elastographic lymph node evaluation

Different imaging techniques can bring different information which will contribute to the final diagnosis and further management of the patients. Even from the time of Hippocrates, palpation has been used in order to detect and characterize a body mass. The so-called virtual palpation has now become a reality due to elastography, which is a recently developed technique. Elastography has already been proving its added value as a complementary imaging method, helpful to better characterize and differentiate between benign and malignant masses. The current applications of elastography in lymph nodes (LNs) assessment by endoscopic ultrasonography will be further discussed in this paper, with a review of the literature and future perspectives.

Can elastography replace fine needle aspiration?

Endoscopic ultrasound (EUS) is one of the best diagnostic methods for diseases of the digestive tract and surrounding organs. Whereas EUS-guided fine needle aspiration (FNA) has been very useful for providing histological confirmation for previously hard to reach lesions, elastography is aiming to obtain a “virtual biopsy” by assessing differences in elasticity between the normal and pathological – usually malignant – tissue. A question that arises is whether EUS-elastography has reached a stage where it might successfully supplant the use of EUS-FNA in some of its clinical indications. The main indications of EUS-guided FNA are listed in this article and published data on the usage of elastography in these settings is reviewed for each one. In some of the indications, a plethora of studies have been published, notably for the evaluation of solid pancreatic masses and lymph nodes, while in others there is little relevant data (submucosal masses, left liver lesions, left adrenal masses), or elastography simply is not suitable as a diagnostic means (cystic lesions). Our conclusion is that elastography is not yet ready to replace EUS-FNA in its indications, but should complement it in various settings, especially for the assessment of lymph nodes. It can only be considered an alternative on a case-by-case basis, in situations where FNA is regarded as a contraindication. Furthermore, it could be used in conjunction with other imaging techniques, such as contrast-enhanced EUS, in order to further improve the accuracy of non-invasive EUS assessment, possibly making the case for a more limited or targeted use of EUS-FNA in selected cases.

Therapeutic endoscopy and endoscopic ultrasound for gastrointestinal malignancies

Gastrointestinal endoscopy and endoscopic ultrasound not only provide strategies to diagnose and stage malignancy, but also to administer palliative and definitive care. Options for anticancer therapy include endoscopic mucosal resection, photodynamic therapy, thermal therapy, self-expanding metal stents and recently, endoscopic ultrasound-guided therapy, such as intratumoral injection. This review summarizes the available endoscopic techniques with a discussion of indications and recent clinical data pertaining to gastrointestinal malignancy. This review will inform the reader of emerging treatment options and stress the importance of incorporating gastroenterologists into the multidisciplinary approach in the management of gastrointestinal cancers.

Role of endoscopic ultrasonography in the staging and treatment of colorectal carcinoma

AIM: To evaluate the use of endoscopic ultrasonography (EUS) in the staging and treatment of colorectal carcinoma.

METHODS: Fifty-six patients who were diagnosed with colorectal cancer by endoscopic biopsy in our department underwent EUS staging (TN). According to the results of EUS staging, the patients were treated with surgery. After postoperative pathologic staging, the patients with stage 2 and stage 3 disease were given adjuvant chemotherapy. Using postoperative pathology as a gold standard, the accuracy of EUS staging was calculated. The patients were followed for over two years and the rate of recurrence was calculated.

RESULTS: The accuracy rates of uT staging for colorectal cancer were 88.89% (T1), 83.33% (T2), 85.71% (T3), and 75.00% (T4), and the total accuracy rate of uT staging for colorectal cancer is 83.23%. The accuracy rates of uN staging were 81.25% (uN(+)) and 80% (uN(-)), and the total accuracy rate of uN staging is 80.63%. Six (10.71%) patients had recurrence.

CONCLUSION: EUS is useful for the staging and treatment of colorectal cancer.

Endoscopic ultrasound elastography

Endoscopic ultrasound (EUS) is a reference technique for diagnosing and staging several different diseases. EUS-guided biopsies and fine needle aspirations are used to improve diagnostic performance of cases where a definitive diagnosis cannot be obtained through conventional EUS. However, EUS-guided tissue sampling requires experience and is associated with a low but not negligible risk of complications. EUS elastography is a non-invasive method that can be used in combination with conventional EUS and has the potential for improving the diagnostic accuracy and reducing the need for EUS-guided tissue sampling in several situations. Elastography measures tissue stiffness by evaluating changes in the EUS image before and after the application of slight pressure to the target tissue by the ultrasonography probe. Pathologic processes such as cancerization and fibrosis alter tissue elasticity and therefore induce changes in elastographic appearance. Qualitative elastography depicts tissue stiffness using different colors, whereas quantitative elastography renders numerical results expressed as a strain ratio or hue histogram mean. EUS elastography has been proven to differentiate between benign and malignant solid pancreatic masses, as well as between benign and malignant lymph nodes with a high accuracy. Studies have also demonstrated that the early changes of chronic pancreatitis can be distinguished from normal pancreatic tissues under EUS elastography. In this article, we review the technical aspects and current clinical applications of qualitative and quantitative EUS elastography and emphasize the potential additional indications that need to be evaluated in future clinical studies.

Endoscopic ultrasound image enhancement elastography

Endoscopic ultrasound (EUS) represents an advance in the diagnosis and staging of several diseases. EUS-guided fine-needle aspiration is useful, but technically demanding, and can be associated with complications. Elastography emerges as a useful tool that is based on the knowledge that some diseases, like cancer, lead to a modification in tissue stiffness. Elastography evaluates the elastic properties of tissues and compares images obtained before and after compression to target tissues; differentiating benign from malignant lesions. This article reviews theoretical aspects and the methodology of EUS elastography. Clinical applications, mainly in pancreatic diseases and lymph nodes, are analyzed.

Imaging in assessing hepatic and peritoneal metastases of gastric cancer: a systematic review

BACKGROUND

Hepatic and peritoneal metastases of gastric cancer are operation contraindications. Systematic review to provide an overview of imaging in predicting the status of liver and peritoneum pre-therapeutically is essential.

METHODS

A systematic review of relevant literatures was performed in Pubmed/Medline, Embase, The Cochrane Library and the China Biological Medicine Databases. QUADAS was used for assessing the methodological quality of included studies and the bivariate model was used for this meta-analysis.

RESULTS

Totally 33 studies were included (8 US studies, 5 EUS studies, 22 CT studies, 2 MRI studies and 5 18F-FDG PET studies) and the methodological quality of included studies was moderate. The result of meta-analysis showed that CT is the most sensitive imaging method [0.74 (95% CI: 0.59-0.85)] with a high rate of specificity [0.99 (95% CI: 0.97-1.00)] in detecting hepatic metastasis, and EUS is the most sensitive imaging modality [0.34 (95% CI: 0.10-0.69) ] with a specificity of 0.96 (95% CI: 0.87-0.99) in detecting peritoneal metastasis. Only two eligible MRI studies were identified and the data were not combined. The two studies found that MRI had both high sensitivity and specificity in detecting liver metastasis.

CONCLUSION

US, EUS, CT and 18F-FDG PET did not obtain consistently high sensitivity and specificity in assessing liver and peritoneal metastases of gastric cancer. The value of laparoscopy, PET/CT, DW-MRI, and new PET tracers such as 18F-FLT needs to be studied in future.

Contrast-enhanced endoscopic ultrasound and elastosonoendoscopy

Until recently, there was no contrast harmonic imaging technique available for EUS examination. Second-generation US contrast agents produce harmonic signals at lower acoustic powers and, therefore, are suitable for EUS imaging at low acoustic powers. CE-EUS could provide a contribution to the differential diagnosis between a primary pancreatic carcinoma, chronic pancreatitis and a pancreatic metastasis, and therefore can have a decisive influence on the selection of appropriate therapeutic strategies (follow-up, chemotherapy or surgery, for example). However, histology remains the standard in the differential diagnosis of pancreatic tumours. Regarding lymph nodes, CE-EUS cannot replace EUS-guided fine-needle aspiration. Elastography examines the elastic properties of tissues by applying a slight compression to the tissue and comparing an image obtained before and after this compression. EUS elastography is a new application in the field of endosonography and seems to be able to differentiate fibrous and benign tissue from malignant lesions. While our results are very encouraging, further research will be needed to further define the place of this new technique and should be aimed at further defining criteria for accurate elastography as well as subsequently assessing the technique using multiple operators in a blinded setting. EUS-guided sonoelastography has the potential for further guiding the diagnosis and therapy of gastrointestinal-related tumours.

Endoscopic ultrasound elastography for evaluation of lymph nodes and pancreatic masses: a multicenter study

AIM

To evaluate the ability of endoscopic ultrasound (EUS) elastography to distinguish benign from malignant pancreatic masses and lymph nodes.

METHODS

A multicenter study was conducted and included 222 patients who underwent EUS examination with assessment of a pancreatic mass (n = 121) or lymph node (n = 101). The classification as benign or malignant, based on the real time elastography pattern, was compared with the classification based on the B-mode EUS images and with the final diagnosis obtained by EUS-guided fine needle aspiration (EUS-FNA) and/or by surgical pathology. An interobserver study was performed.

RESULTS

The sensitivity and specificity of EUS elastography to differentiate benign from malignant pancreatic lesions are 92.3% and 80.0%, respectively, compared to 92.3% and 68.9%, respectively, for the conventional B-mode images. The sensitivity and specificity of EUS elastography to differentiate benign from malignant lymph nodes was 91.8% and 82.5%, respectively, compared to 78.6% and 50.0%, respectively, for the B-mode images. The kappa coefficient was 0.785 for the pancreatic masses and 0.657 for the lymph nodes.

CONCLUSION

EUS elastography is superior compared to conventional B-mode imaging and appears to be able to distinguish benign from malignant pancreatic masses and lymph nodes with a high sensitivity, specificity and accuracy. It might be reserved as a second line examination to help characterise pancreatic masses after negative EUS-FNA and might increase the yield of EUS-FNA for lymph nodes.

Endoscopic ultrasound elastography for evaluation of lymph nodes and pancreatic masses: A multicenter study

AIM: To evaluate the ability of endoscopic ultrasound (EUS) elastography to distinguish benign from malignant pancreatic masses and lymph nodes.

METHODS: A multicenter study was conducted and included 222 patients who underwent EUS examination with assessment of a pancreatic mass (n = 121) or lymph node (n = 101). The classification as benign or malignant, based on the real time elastography pattern, was compared with the classification based on the B-mode EUS images and with the final diagnosis obtained by EUS-guided fine needle aspiration (EUS-FNA) and/or by surgical pathology. An interobserver study was performed.

RESULTS: The sensitivity and specificity of EUS elastography to differentiate benign from malignant pancreatic lesions are 92.3% and 80.0%, respectively, compared to 92.3% and 68.9%, respectively, for the conventional B-mode images. The sensitivity and specificity of EUS elastography to differentiate benign from malignant lymph nodes was 91.8% and 82.5%, respectively, compared to 78.6% and 50.0%, respectively, for the B-mode images. The kappa coefficient was 0.785 for the pancreatic masses and 0.657 for the lymph nodes.

CONCLUSION: EUS elastography is superior compared to conventional B-mode imaging and appears to be able to distinguish benign from malignant pancreatic masses and lymph nodes with a high sensitivity, specificity and accuracy. It might be reserved as a second line examination to help characterise pancreatic masses after negative EUS-FNA and might increase the yield of EUS-FNA for lymph nodes.

Pathophysiology, clinical presentation, and management of colon cancer

Colon cancer is believed to arise from two types of precursor polyps via two distinct pathways: conventional adenomas by the conventional adenoma-to-carcinoma sequence and serrated adenomas according to the serrated adenoma-to-carcinoma theory. Conventional adenomas arise from mutation of the APC gene; progression to colon cancer is a multistep process. The fundamental genetic defect in serrated adenomas is unknown. Environmental factors can increase the risk for colon cancer. Advanced colon cancer often presents with symptoms, but early colon cancer and premalignant adenomatous polyps commonly are asymptomatic, rendering them difficult to detect and providing the rationale for mass screening of adults over age 50.

Gastrointestinal stromal tumors: Imatinib and beyond

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract. Clinicians previously classified GISTs as "benign" or "malignant," but now place resected tumors in risk categories that are based on size and mitotic rate. Historically, GIST patients were managed with surgery alone, as chemotherapy and radiotherapy have minimal activity in this disease. In the pre-imatinib era, patients with recurrent or metastatic disease generally did very poorly. GIST therapy was revolutionized following the discovery of oncogenic mutations in the c-kit gene, as well as in the platelet-derived growth factor receptor. Subsequently, it has been confirmed that the KIT receptor tyrosine kinase is both a diagnostic marker and a useful therapeutic target in GIST. Imatinib, a potent inhibitor of KIT activity, is now standard front-line therapy for advanced GIST. With the introduction of imatinib, there have been dramatic improvements in response rates, time to progression, and survival. Imatinib is now being investigated and shows promise in the neoadjuvant and adjuvant settings. Unfortunately, many patients eventually recur or progress during imatinib therapy. For these patients, imatinib dose escalation and/or surgical evaluation are appropriate. Additionally, a novel tyrosine kinase inhibitor such as SU11248 (sunitinib) is a reasonable option for progressive, imatinib-resistant disease. With the identification of other downstream pathways, several other promising therapies are under current investigation either alone or in combination with imatinib and surgery.

Can U.S. GI fellowship programs meet American Society for Gastrointestinal Endoscopy recommendations for training in EUS? A survey of U.S. GI fellowship program directors

BACKGROUND

American Society for Gastrointestinal Endoscopy (ASGE) EUS training and credentialing guidelines exist, but the capability of U.S. GI fellowships to meet these guidelines has not been assessed.

OBJECTIVE

To ascertain the capability of U.S. GI fellowship programs to meet ASGE guidelines for EUS training in the context of 3-year and advanced GI fellowships.

METHODS

U.S. GI fellowship programs were surveyed for the presence or the absence, type, and extent of EUS training. Demographics regarding the programs and the program directors were obtained.

MAIN OUTCOME MEASUREMENTS

Data on the annual total EUS volume and data on EUS performed by 3-year and/or advanced-year fellows were collected and analyzed.

RESULTS

Ninety-one of 142 contactable GI programs responded (64%); 72% of programs performed >200 EUS/y and thus could train >or=1 EUS trainee/y. For 3-year GI fellows, 55% received less than 3 months of training, with 43% not receiving actual "hands-on" EUS experience, and 61% not learning EUS-guided FNA. The median EUS performed by 3-year fellows was 50 (0-350). Programs that offer advanced endoscopy fellowship had a median advanced-trainee EUS volume of 200 procedures (range, 50-1100 procedures). Of advanced fellows, 20% failed to receive "hands-on" training and 52% performed <200 procedures. We observed a significant difference in the median EUS volume performed by 3-year versus advanced-year fellows (P<.001). Program director variables did not correlate with training EUS volumes.

CONCLUSIONS

The majority of U.S. GI fellowship programs have established the EUS volume to train at least 1 EUS fellow, per ASGE guidelines; however, most 3-year and many advanced fellows are currently receiving insufficient EUS training.

Gastric GI stromal tumors (GISTs): The role of surgery in the era of targeted therapy

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal neoplasm arising in the stomach. These tumors were previously classified as smooth muscle tumors, but in recent years it has become clear that they are clinically, pathologically, and molecularly distinct from other tumors and are much more common than previously appreciated. Historically, patients with primary localized or advanced GIST have been managed surgically, as there was no proven role of other treatment modalities such as radiation or chemotherapy. However, the field of GIST was revolutionized with the 1998 discovery that the vast majority of these tumors have oncogenic gain-of-function mutations of the KIT receptor tyrosine kinase. Follow-up studies have confirmed that KIT is both a useful diagnostic marker and an excellent therapeutic target. Imatinib, an inhibitor of KIT kinase activity, is now the standard front-line therapy for patients with advanced GIST. In this review, we discuss pathological and molecular features of gastric GISTs and review the historic and current roles of surgery in the treatment of patients with primary or metastatic GIST. The importance of a multi-disciplinary approach using both surgery and imatinib therapy is emphasized.