Characterization of solid focal pancreatic lesions using endoscopic ultrasonography with real-time elastography

Abstract

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.

Key Words::

• endoscopic ultrasonography
• focal pancreatic lesions
• real-time elastography
• strain quantification
• strain ratio
• tissue characterization

Acknowledgments

We thank Dr Dag Hoem at Department of Surgery and Eva Fosse RN at National Centre for Ultrasound in Gastroenterology, Medical Department, Haukeland University Hospital for their contribution. We also thank Professor Geir Egil Eide at Centre for Clinical Research, Haukeland University Hospital, for counseling on statistical methods. The equipment used in this study was partially financed by donations from “Kjøpmann Olaf Rundshaugs Legat” and Olav Raagholt and Gerd Meidel Raagholts Research Foundation, Norway.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper. The study was supported by MedViz (http://medviz.uib.no/), an interdisciplinary research cluster from Haukeland University Hospital, University of Bergen and Christian Michelsen Research AS.