Background: Pancreatic steatosis (PS), or fatty pancreas, characterized by increased fat deposition in pancreatic parenchyma, is associated with metabolic disorders and an elevated risk of pancreatic cancer. Due to the anatomical positioning of the pancreas, tissue sampling for PS diagnosis presents challenges. Noninvasive imaging, especially endoscopic ultrasound (EUS), is a valuable diagnostic tool; however, current criteria such as the Paul Sepe criteria lack histological validation.

Objective: To develop novel EUS diagnostic criteria for PS with histological confirmation.

Methods: We prospectively enrolled patients undergoing pre-operative EUS before pancreatic surgery, including pancreaticoduodenectomy and distal pancreatectomy. Assessments of PS via EUS were verified with histopathological analysis, with PS defined as greater than 6.2% fat infiltration in the pancreatic parenchyma. EUS evaluations, conducted by two experienced endoscopists, were used to determine inter-observer agreement (IOA). Novel EUS criteria were developed using multivariate logistic regression analysis of pancreatic parenchymal and ductal features, and a simplified scoring system was developed by converting beta-coefficients into integer points. Finally, the novel EUS criteria were compared for diagnostic performance with the Paul Sepe criteria.

Results: Of the 132 patients enrolled from July 2020 to January 2023, 96 completed the study protocol. The mean age was 65.7 ± 12.0 years, with males comprising 52.0% of the cohort. Postoperative diagnoses predominantly included pancreatic ductal adenocarcinoma (37.5%), ampullary carcinoma (17.7%), and pancreatic cystic neoplasms (14.6%). Histological analysis identified PS in 27.1% of patients. The novel EUS criteria (table1) included scoring for hyperechoic parenchyma (2 points), obscured pancreatic ducts (3 points), and fibrotic features (-2 points for 1-2 features, -3 points for ≥ 3 features). A score cutoff of 2 points provided optimal diagnostic performance with a sensitivity of 96.2% (95%CI = 80.4-99.9), specificity of 82.9% (95%CI = 72.0-90.8), positive predictive value of 67.6% (95%CI = 50.2-82.0), and negative predictive value of 98.3% (95%CI = 90.9-100.0), surpassing the diagnostic performance of the Paul Sepe criteria (AUROC 0.96 [95%CI = 0.91-0.99] vs. 0.86 [95%CI = 0.77-0.95]; p=0.006). The new criteria also exhibited good IOA (kappa = 0.802).

Conclusion: This is the first EUS criteria for PS developed based on histology as the gold standard. The novel EUS criteria offer good diagnostic performance for PS with good IOA. These straightforward and practical criteria can be applied in clinical practice.

Logistic regrssion analysis and score development

Diagnostic performance and inter-observer agreement

Yongyut Sirivatanaukson

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