Acinar Filling After Secretin Stimulation: Association with Pancreatic Dysfunction and Structural Damage in Secretin-Enhanced MRCP

Abstract Purpose To investigate the clinical significance of acinar filling observed during secretin-enhanced magnetic resonance cholangiopancreatography (s-MRCP) in patients undergoing pancreatic evaluation. Materials and Methods This retrospective study analyzed 1,283 consecutive s-MRCP examinations performed between 2005–2018. Acinar filling was defined as parenchymal T2 hyperintensity developing during secretin stimulation. Clinical, functional, and morphological parameters were compared between patients with and without acinar filling using univariate analysis and multivariate logistic regression. Exocrine function was assessed using duodenal filling grade (Matos score 0–3). Results Acinar filling was present in 67/1,283 patients (5.2%). In multivariate analysis, independent predictors included Cambridge grade (OR = 1.71, 95% CI 1.42–2.06, p0.001), age (OR = 1.68 per SD, 95% CI 1.27–2.22, p0.001), sphincter of Oddi dysfunction (SOD) (OR = 2.07, 95% CI 1.00-4.29, p = 0.050), and hyperenzymemia (OR = 1.75, 95% CI 1.01–3.05, p = 0.047). Importantly, acinar filling occurred predominantly in patients with preserved exocrine function (Matos score 2.8 ± 0.5, with 85% demonstrating complete duodenal filling), suggesting a functional-obstructive mechanism. The multivariate model achieved acceptable discriminative ability (AUC = 0.744). Among patients with morphologically normal pancreas (Cambridge 0), acinar filling remained associated with SOD (11.8% vs 2.7%, p = 0.006). Conclusion Acinar filling during s-MRCP is independently associated with SOD, hyperenzymemia, structural pancreatic damage, and older age. The occurrence of acinar filling predominantly in patients with preserved exocrine function supports a functional-obstructive mechanism wherein adequate pancreatic secretion accumulates in acinar spaces under conditions of relative ductal obstruction. This finding may represent a pathological marker warranting clinical attention.