Incident-angle dependence of the phase conjugate reflectivity by nonlinear piezoelectric interaction in PZT ceramics

Endoscopic ultrasound elastography for small solid pancreatic lesions with or without main pancreatic duct dilatation

BACKGROUND

/Objectives: Endoscopic ultrasound elastography (EUS-EG) is useful for diagnosis of small solid pancreatic lesions (SPLs), particularly in excluding pancreatic cancer (PC), but its dependence on main pancreatic duct dilatation (MPDD) has not been examined. We aimed to investigate EUS-EG for diagnosis of small SPLs with and without MPDD.

METHODS

Patients with pathologically diagnosed SPLs of ≤20 mm were included and retrospectively analyzed. Using the blue:green ratio, an EUS-EG image was classified as blue-dominant, equivalent, or green-dominant. Using multiple EUS-EG images per patient, a lesion with a greater number of blue-dominant than green-dominant images was classified as stiff, and the others as soft. EUS-EG images in random order were judged by three raters. Considering stiff SPLs as PC, diagnostic performance of EUS-EG was examined for SPLs with and without MPDD.

RESULTS

Of 126 cases analyzed, 65 (52%) were diagnosed as PC, and 63 (50%) had MPDD. A total of 1077 EUS-EG images were examined (kappa coefficient = 0.783). Lesions were classified as stiff in 91 cases and soft in 35 (kappa coefficient = 0.932). The ratio of stiff to soft lesions was significantly higher in PC than in non-PC (62:3 vs. 29:32, P < 0.001). The sensitivity, specificity, and negative predictive value of a stiff lesion with vs. without MPDD for diagnosis of PC were 94%, 23%, and 50% vs. 100%, 60%, and 100%, respectively.

CONCLUSIONS

Using the EUS-EG stiffness classification for small SPLs, PC can be excluded with high confidence and concordance for a soft lesion without MPDD.

Do we need elastography for EUS?

We recently introduced a series of papers “What should be known prior to performing EUS exams.” In Part I, the authors discussed which clinical information and whether other imaging modalities are needed before embarking EUS examinations. In Part II, technical controversies on how EUS is performed were discussed from different points of view. In this article, important practical issues regarding EUS elastography will be raised and controversially discussed from very different points of view.