Magnetic resonance cholangiopancreatography findings in early chronic pancreatitis diagnosed according to the Japanese Diagnostic Criteria.

Objectives: It is important for diagnosing early chronic pancreatitis (CP), which may be improved by therapeutic intervention. We aimed to examine the pancreatic ductal changes on magnetic resonance cholangiopancreatography (MRCP) in patients with early CP defined by the Japanese Diagnostic Criteria.

Methods: This retrospective study included patients suspected early CP and performed both endoscopic ultrasonography (EUS) and MRCP from January 2010 to August 2018. We assessed the diameter of the main pancreatic duct (MPD) and the number of irregularly dilated duct branches using MRCP imaging in early CP.

Results: We enrolled 165 patients and 25 patients (15%) fulfilled the diagnostic criteria for early CP. Irregular dilatation of ≥ 3 duct branches on MRCP was more often observed in early CP compared to non-early CP (P = 0.004), although MPD diameter was comparable (2.06 mm in early CP vs. 1.96 in non-early CP, P = 0.698). The sensitivity and specificity were 45% and 74%, respectively. The prevalence of positive MRCP findings in patients with ≥ 2 positive EUS findings was higher than that in patients with 1 positive EUS finding (P = 0.08) and in patients without an EUS finding (P < 0.001). There was no difference in the average diameter of MPD.

Conclusion: Patients with early CP often exhibit alteration in duct branches and not in MPD in addition to parenchymal alteration. Both pancreatic parenchyma and duct branches might need to be evaluated by EUS and MRCP.