OBJECTIVES. The aim of this study was to evaluate the diagnostic potential of strain assessment in solid focal pancreatic lesions using real-time elastography in combination with endoscopic ultrasonography (EUS). MATERIAL AND METHODS. Forty-eight solid focal pancreatic lesions in 39 patients were included prospectively over a 3-year period and studied by EUS with real-time elastography (EUS-RTE). Lesions previously described as cystic by CT were not included. Distribution patterns of tissue strain were assessed using strain ratio (SR) measurements, continuous visual analog scale (VAS), and a visual categorical score (VCS), based on color coding of relative strain. Final diagnosis was based on histopathology, fine-needle aspiration cytology, and/or follow-up for ≥6 months. RESULTS. The 48 lesions included 11 adenocarcinomas, 7 malignant neuroendocrine tumors (NETs), 11 benign or indeterminate NETs, 8 focal pancreatic lesions, 2 microcystic adenomas, and 9 other benign lesions. Malignant lesions had significantly higher median SR (7.05 vs. 1.56) and VAS scores (93.0 vs. 63.5) than benign lesions. A receiver operation characteristic curve analysis showed sensitivity of 67% and specificity of 71%, when using SR = 4.4 as a cut-off for malignancy. The highest SR values were found in two benign microcystic adenomas. CONCLUSIONS. EUS-RTE with SR measurements and VAS evaluation demonstrated a significant strain difference between benign and malignant lesions. However, the variation within the entities was substantial and some benign lesions presented with low strain. Benign lesions were generally characterized by a strain similar to reference tissue, whereas malignant lesions were harder. The recorded strain pattern in individual lesions must be interpreted with caution.
Keywords: endoscopic ultrasonography; focal pancreatic lesions; real-time elastography; strain quantification; strain ratio; tissue characterization.