6.2　New Techniques Associated to EUS

6.2　New Techniques Associated to EUS

6.2.1　EUS-Guided Elastography

In recent years，there has been increasing interest in assessing the role of elastography on the evaluation of solid pancreatic tumors，but few studies focus on the management of CP.In 2007，a study was conducted by Janssen J.et al.to investigate the feasibility of EUS elastography of the pancreas（Janssen et al.2007）.They found that EUS elastography could distinguish normal pancreas from CP or pancreatic tumor，but CP and hard tumors cannot be distinguished by elastography.However，another study found there are significant direct linear correlation between the number of EUS criteria of CP and the strain ratio（Iglesias-Garcia et al.2013）.And，the strain ratio varied significantly in different Rosemont classification groups.Therefore，EUS-elastography maybe was an accurate tool for the diagnosis of CP and provided relevant and objective information to support EUS findings.But its role need to be further studied.In the last study，EUSelastography was used to predict the pancreatic exocrine insufficiency（PEI）of CP patients.It was found that there a direct relationship between strain ratio and the probability of PEI.Strain ratio allows quantification of the probability of PEI in patients with CP（Dominguez-Munoz et al.2015）.

6.2.2　EUS-Guided Contrast Enhancement

The role of contrast enhancement EUS（CE-EUS）in diagnosis of CP has not yet been determined.Most studies focus on the differential diagnosis of pancreatic cancer and focal CP（Saftoiu et al.2015）.However few studies described the CE-EUS feature of CP.One study found CE-EUS enhances the lobular pattern seen by convention EUS in CP patients（Saftoiu et al.2012）.In addition，compared with control，the washout of contrast in CP patients was significantly faster.(https://www.daowen.com)

6.2.3　Computer Aided Diagnosis（CAD）Based EUS

Although EUS plays an important role in diagnosis of CP，the interpretation of EUS imaging is heavily subjective.EUS images contain medical information regarding textural features that can aid disease diagnosis by using CAD image analysis techniques.Previous studies have demonstrated the ability of EUS imaging with textural feature analyses to improve CP diagnosis（Irisawa et al.2004；Das et al.2008）.Zhu et al.（2013）combined image analyses with CAD techniques to establish a classification model for EUS imaging to distinguish pancreatic cancer from CP accurately，based on an SVM model，with an accuracy of 96.3%，sensitivity of 93.4%and specificity of 92.2%.In our last study，a new descriptorwas introduced for CAD and able to differentiate CP from autoimmune pancreatitis（Zhu et al.2015）.

Conclusion

EUS can be considered as first choices for the morphological diagnosis of CP，as a result of it display small changes of the pancreatic parenchyma or duct.EUS-FNA/B and EUS-TCB could provide specimen for histological diagnosis，but those techniques are not currently recommended for evaluation of this disease due to potential complications and limited diagnostic yield.They are often used for distinguish of CP from pancreatic tumors.New techniques based on EUS provide a new perspective for CP diagnosis.But more studies need to be conducted to evaluate their utility.