Rationale and objectives: To measure main pancreatic duct diameter (PDD) with magnetic resonance pancreatography (MRP) before and after secretin injection in patients with suspected sphincter of Oddi dysfunction (SOD) and to determine if the diameter change is predictive of sphincter of Oddi manometry (SOM) results.
Materials and methods: We identified all patients during the study period referred for SOM for clinically suspected SOD; patients with an intact sphincter and without contraindication to MRP examination were considered for study entry. Consenting patients underwent MRP, including dynamic imaging of the pancreatic duct after intravenous administration of porcine secretin followed by SOM during endoscopic retrograde cholangiopancreatography. MRP was defined as abnormal when PDD remained increased by > or = 1.0 mm from baseline 15 minutes after secretin injection. SOM was abnormal when basal sphincter pressure (SP) was > or = 40 mm Hg. Mean PDD before and after secretin administration was compared within normal and abnormal SP groups with two-tailed unpaired t-test; the mean difference between baseline and peak PDD and duration of > or = 0.5 mm increase in PDD was compared between groups with two-tailed t-test. P < .05 was considered significant.
Results: Of 70 patients referred for SOM, 30 met all entry criteria, gave consent to participate, and underwent both MRP and SOM. Ten of 30 patients (33%) had normal SP; 20 (67%) were abnormal. PDD increased significantly after secretin injection (normal SP, 1.62 +/- 0.73 to 2.78 +/- 0.77 mm, P < .01; abnormal SP, 1.45 +/- 0.26 to 2.32 +/- 0.75 mm, P < .01). There was no difference between normal and abnormal SP groups in amount of PDD increase (1.15 +/- 0.75 vs. 0.88 +/- 0.72 mm; P = .33) or duration of > or = 0.5 mm increase in PDD (5.28 +/- 8.76 vs. 13.60 +/- 13.00 minutes; P = 0.07).
Conclusions: In patients with suspected sphincter of Oddi dysfunction, magnetic resonance pancreatography demonstrated PDD increase following secretin injection but did not predict the results of manometry.