Applications of Endoscopic Ultrasound-Elastography.

Dear Sir,

Endoscopic ultrasound (EUS)-elastography is a noninvasive 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. The combination of EUS and elastography can assess the elasticity of tumors in the proximity of the digestive tract such as pancreatic masses and lymph nodes that are hard to reach with conventional transcutaneous US probes. EUS-elastography can be used to characterize enlarged lymph nodes associated with malignancies such as lymphoma or inflammatory diseases such as sarcoidosis.[1] EUS-elastography is a promising, noninvasive method for the differential diagnosis of malignant lymph nodes and may become a valuable supplemental method to EUS-guided fine-needle aspiration biopsy (FNAB). Given the current indications for conventional EUS, EUS-elastography may be useful in evaluating solid lesions in left suprarenal glands by differentiating between adenomas and metastases.[2] EUS-elastography can accurately estimate the stage of chronic liver diseases and provide excellent images of the medial two-thirds of the liver. Ongoing clinical trials on the utility of EUS-elastography to predict portal hypertension are in process. Choledocholithiasis and chronic inflammatory or sclerosing processes may cause stiffness of the bile duct walls which can readily be assessed on EUS-elastography. EUS-elastography with computer-aided pixel analysis can significantly improve the specificity of lymph nodal staging in patients with esophageal carcinoma. Real-time tissue elastography can more accurately diagnose lymph nodal metastasis in esophageal carcinoma and can simultaneously aid in obtaining biopsy samples. EUS-elastography is the most efficient diagnostic method for local staging of gastric cancer, being able to differentiate between early and advanced primary gastric tumors and as a complementary method for the characterization and differentiation of benign and malignant lymph nodes in real time. EUS-guided FNAB is indicated in gastric cancer if it has a net positive benefit on the clinical management of the patient. The use of EUS-elastography for determining the infiltration of adjacent organs in the staging of gastric and esophageal cancers is currently being evaluated.[3] EUS-elastography is increasingly being used for targeted FNAB of hard and most suspicious areas of the lesion with improved accuracy. EUS-elastography can provide diagnostic information on malignant subepithelial masses such as gastrointestinal stromal tumors regarding the stiffness, which helps in increasing the diagnostic confidence and accuracy of staging. EUS-elastography is a promising technique with a high degree of accuracy for the differential diagnosis of solid pancreatic tumors.[4] It allows for a quantitative and objective evaluation of tissue stiffness, which indicates the malignant or benign nature of the pancreatic lesion. The differentiation between mass-forming chronic pancreatitis, autoimmune pancreatitis, and malignant lesions of pancreas can be evaluated on EUS, with the stiff appearance of the mass lesion and the surrounding pancreatic parenchyma distinguishing ductal adenocarcinoma from chronic pancreatitis and normal pancreas. EUS evaluation of rectal wall thickness and strain ratios for diagnosing inflammatory bowel disease and differentiating Crohn's disease from ulcerative colitis is being investigated.[5] The value of transrectal EUS-elastography has been investigated for the diagnosis and evaluation of prostate cancer, rectal cancer, inflammatory bowel disease, and fecal incontinence.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.