Prior Endoscopic Sphincterotomy Can Affect the Interpretation of Secretin-Stimulated Magnetic Resonance Cholangiopancreatography (S-MRCP)

Abstract

Purpose: Lack of pancreatic duct compliance and decreased duodenal filling on secretin-stimulated magnetic resonance cholangiopancreatography (S-MRCP) has been noted in patients with chronic pancreatitis. As to whether or not endoscopic sphincterotomy (ES) can affect pancreatic duct compliance and duodenal filling on diagnostic S-MRCP is unknown. The purpose of this study was to determine if pancreatic duct compliance and duodenal filling on S-MRCP in patients without evidence of chronic pancreatitis was different in those with and without ES. Methods: A retrospective review of patients who were referred to our pancreatico-biliary clinic from 12/06–12/07 was performed. Those patients who had no evidence of chronic pancreatitis (normal fecal elastase 1 levels and normal MRI or CT imaging and/or normal endoscopic pancreatic function tests) and who underwent S-MRCP were studied. S-MRCP findings were analyzed, specifically noting change in pancreatic duct diameter size from baseline to max dilation after secretin administration (0.2 mcg/kg IV dose of human secretin), the time to achieve max dilation, and the grade of duodenal filling at peak diameter. A single observer measured and recorded all measurements, and the mean for pancreatic duct diameter change, time to peak change, and duodenal filling were calculated. Results: Of the 34 patients studied, 12 had ES and 22 had intact sphincters of Oddi. In the sphincterotomy group, there was a mean change of 0.17 mm (range 0.01–0.35), while in the non-sphincterotomy group, the mean change was 0.91 mm (range 0.31–1.97) after secretin administration. The difference was significant with a P < 0.005. Though there was a trend towards a longer time to maximal pancreatic duct dilation and lower duodenal filling at peak pancreatic duct diameter in those patients with an intact native sphincter of Oddi, these results were not statistically significant. In addition, there was no difference in those patients who had only a biliary sphincterotomy compared to those with both biliary and pancreatic sphincterotomies. Conclusion: Endoscopic sphincterotomy significantly decreases pancreatic duct dilation in response to secretin on S-MRCP. However, further studies are required to determine the effect of sphincterotomy on the amount of duodenal filling and the rate at which duodenal filling occurs. As S-MRCP is quickly becoming an increasingly utilized non-invasive method for documenting chronic pancreatitis, one must be aware of the absence of a functional pancreatic sphincter (s/p sphincterotomy) when reading S-MRCP, to avoid misinterpretation of pancreatic duct compliance.