EUS Elastography in Differential Diagnosis of Autoimmune/Pseudotumoral Pancreatitis and Pancreatic Adenocarcinoma

According to EFSUMB guidelines (Săftoiu et al., 2019; Jenssen et al., 2016; Cosgrove et al., 2013), endoscopic ultrasound (EUS) elastography is used for differentiation of benign and malignant solid pancreatic lesions, as well as for discrimination between adenocarcinoma and inflammatory (including pseudotumoral) masses.

Elastography Techniques

Qualitative and quantitative approaches are mentioned in the literature: strain ratio (deformation coefficient) and strain histograms. The combination of EUS-FNA and elastography (strain ratio) was studied for exclusion of malignant solid pancreatic lesions (Kongkam et al., 2015). Quantitative elastography is described as an accurate method for differentiation of solid lesions (Iglesias-García et al., 2010), and the combination of elastography with strain ratio — for diagnosis of solid masses (Itokawa et al., 2011).

Inflammatory Masses versus Adenocarcinoma

Meta-analyses cited in the guidelines evaluated elastography for discrimination between benign and malignant lesions (Xu et al., 2013; Mei et al., 2012; Pei et al.) and separately — for differentiation of pancreatic adenocarcinoma and inflammatory masses (Li et al., 2013). Specific threshold values for deformation coefficients are not provided in the literature [clarification needed].

Role of Contrast Techniques in Autoimmune/Pseudotumoral Pancreatitis

For differential diagnosis of autoimmune pancreatitis and pancreatic cancer, contrast technologies are noted in the literature: quantitative low-mechanical CEUS-EUS for differentiation of chronic pseudotumoral pancreatitis and cancer (Gheonea et al., 2013) and quantitative perfusion analysis with contrast-harmonic EUS (CH-EUS) for differentiation of autoimmune pancreatitis from carcinoma (Imazu et al., 2012; Sidhu et al., 2018). Transabdominal CEUS demonstrates differences in perfusion patterns: time-dependent parameters (arrival time, time-to-peak) are significantly longer in PDAC compared to focal inflammatory masses (Kersting et al., 2009; Hagen-Ansert, 2023). CEUS in autoimmune pancreatitis was compared with pathomorphology (Numata et al., 2004).

Combined Approach

The guidelines emphasize the value of combining modalities: the combination of contrast power Doppler and real-time elastography in EUS was applied for differential diagnosis of focal pancreatic lesions (Săftoiu et al., 2010). Elastography should be used in combination with EUS-FNA to increase diagnostic reliability (Kongkam et al., 2015).