Introduction
Pancreatic neuroendocrine neoplasms (PNENs) are rare tumors from pancreatic endocrine cells, accounting for 1–2% of pancreatic malignancies. Their incidence is rising due to improved diagnostics and awareness. WHO grading—based on mitotic index and Ki-67—is the main prognostic factor. Grade 1 non-functional PanNETs <2 cm are often surveilled, while G2/G3 tumors need active treatment. Accurate preoperative grading is therefore essential. EUS-guided fine-needle aspiration (EUS-FNA) is the main diagnostic tool, though differentiating G1 from G2/3 tumors is difficult, with frequent grading misclassification. Contrast-enhanced EUS (CE-EUS) improves accuracy: low-grade PNENs show early hyperenhancement with washout, while high-grade tumors, with lower microvascular density, appear hypoenhancing. Still, CE-EUS interpretation is subjective. Artificial intelligence (AI) can enhance diagnostic precision.
Aims & Methods
This retrospective multicenter study aimed to evaluate AI in analyzing CE-EUS video sequences to predict PNEN grade. Conducted at San Raffaele Hospital, it included adults with PNEN confirmed by surgery or EUS-FNA, Ki-67 immunostaining, and CE-EUS videos (≥1 min, arterial + venous phases). Exclusions: MiNENs, missing grading, poor-quality videos, lack of consent, or non-pancreatic NETs. EUS was performed by experts using Pentax echoendoscopes and Sonovue®. Tumors were graded per WHO 2019. Videos were anonymized, ROIs manually selected by two experts, and transferred to IHU Strasbourg for AI analysis. CE-EUS videos were processed using a video transformer AI model. Patients were split into training (70%), validation (10%), and test (20%) cohorts. Multiple models were tested; the best-performing one was selected. Accuracy was assessed via precision (PPV), recall (sensitivity), and F1-score.
Results
115 patients (77 males, 66.9%) were included: 70 G1 and 45 G2 tumors. Median lesion size (G1: 17 mm vs. G2: 16 mm), tumor location (head: 41.2% vs. 32%), and stiffness (rigid: 52.9% vs. 55.5%) did not differ significantly. At diagnosis, 15.7% of G1 and 26.7% of G2 had metastases. AI analysis identified G1 tumors with 67% precision, 86% recall, F1-score 75%. The GradAINet model showed strong performance: sensitivity 0.817 (95% CI: 0.556–1.000), specificity 0.806 (CI: 0.588–1.000), PPV 0.759, NPV 0.856, and accuracy 0.811. By grade, G1 sensitivity was 0.796, specificity 0.817, PPV 0.859, NPV 0.741, accuracy 0.805. For G2–G3, sensitivity was 0.817, specificity 0.796, PPV 0.741, NPV 0.859, accuracy 0.805.
Conclusion
EUS-based grading shows 80.3% concordance with surgical findings, often underestimating tumor grade. This is the first study using deep learning on full CE-EUS video sequences, analyzing arterial and venous phases separately. GradAINet achieved high accuracy (0.811), outperforming static image methods. Further multicenter validation and integration of clinical/molecular data are needed to confirm generalizability.