Abstract
INTRODUCTION: Sound speed correction endoscopic ultrasound (SSC-EUS) is a novel imaging technique with limited previous validation. The aim of this study was to evaluate the diagnostic efficacy of SSC-EUS for solid pancreatic lesions (SPL) and compare it with B-mode endoscopic ultrasound (B-EUS), elastography endoscopic ultrasound (EG-EUS), and contrast-enhanced endoscopic ultrasound (CE-EUS). METHODS: A prospective, single-blind, randomized trial included 240 patients with computed tomography/magnetic resonance imaging-confirmed SPL (solid portion >80% of lesion volume). Participants were equally divided into 4 groups (B-EUS, EG-EUS, CE-EUS, and SSC-EUS). Diagnostic thresholds were determined through receiver operating characteristic curves. Subgroup analyses assessed the impact of lesion location (head/body/tail), tumor size (≤3 vs >3 cm), and cancer stage (I/II vs III/IV). Statistical analysis used SPSS 23.0 and GraphPad Prism 8. RESULTS: Among 240 patients, 138 (57.5%) had malignant lesions. SSC-EUS achieved optimal diagnostic performance at a cutoff sound speed of 1,563 m/s (area under the receiver operating characteristic curve = 0.822, sensitivity = 82.8%, specificity = 78.9%, accuracy = 81.7%). CE-EUS demonstrated the highest overall efficacy (sensitivity = 90.3%, specificity = 82.8%, accuracy = 86.7%), followed by SSC-EUS and EG-EUS, both outperforming B-EUS (accuracy = 70.0%). Subgroup analysis revealed superior sensitivity for pancreatic body lesions (SSC-EUS: 87.5%; CE-EUS: 90.0%), tumors >3 cm (SSC-EUS: 84.2%; CE-EUS: 90.0%), and stage III/IV cancers (SSC-EUS: 81.8%; CE-EUS: 90.9%). EG-EUS strain ratio (cutoff = 4.44) showed limited accuracy (61.7%), whereas elastic strain value A (cutoff = 0.065%) exhibited moderate utility (accuracy = 75.0%). DISCUSSION: CE-EUS remains the most effective imaging modality for SPL diagnosis. SSC-EUS demonstrates comparable accuracy with EG-EUS and is particularly advantageous for larger tumors (>3 cm) and advanced-stage malignancies. EG-EUS strain ratio lacks clinical robustness, whereas elastic strain value A warrants further validation. Tailoring imaging method selection to lesion characteristics (location, size, and stage) may optimize diagnostic outcomes.