Indications and limitations of endoscopic ultrasound elastography for evaluation of focal pancreatic lesions

Background and study aim: Endoscopic-ultrasound-guided elastography (EUS-elastography) is a recently introduced imaging procedure that distinguishes tissues on the basis of their specific consistency. The aim of this prospective study was to investigate the role of this new technique in the characterization and differentiation of focal pancreatic lesions. Patients and methods: This prospective study enrolled 70 patients with unclassified solid lesions of the pancreas and 10 controls with a healthy pancreas. In all patients elastography recordings were compared with cytology/histology findings as the gold standard. Results: Adequate EUS-elastography of the pancreas was performed in all healthy controls but in only 56% of patients with solid pancreatic lesions. The main limitation of elastographic image acquisition was incomplete delineation of the border of lesions greater than 35 mm in diameter (39%) or of lesions at some distance from the transducer (10%). Elastographic recordings were also hampered by the fact that the surrounding tissue, which is used as an internal reference standard for strain calculation, was insufficiently displayed in the case of larger lesions. The reduced ratio of target to surrounding tissue resulted in the formation of color artifacts and in impaired reproducibility. In contrast, the majority of lesions smaller than 35 mm in diameter were adequately and reproducibly evaluated by EUS-elastography (91%). The clinical use for differential diagnosis, however, seems limited, since strain images from all kinds of pancreatic masses were found to be harder than the surrounding tissues, irrespective of the underlying nature of the lesion (i.e., malignant vs. benign). EUS-elastography predicted the nature of pancreatic lesions with poor diagnostic sensitivity (41%), specificity (53%), and accuracy (45%). Conclusion: EUS-elastography of the pancreas has the potential to obtain some complementary information that would improve tissue characterization. Its clinical utility, however, remains questionable, and it seems unlikely that the information provided will obviate the necessity of obtaining tissue samples for confirmation of a final pathologic diagnosis.