High-b-value diffusion-weighted magnetic resonance imaging of pancreatic cancer and mass-forming chronic pancreatitis:: Preliminary results

Background: Mass-forming chronic pancreatitis may mimic a pancreatic cancer on dynamic computed tomography (CT) and magnetic resonance (MR) imaging, and preoperative differential diagnosis is often difficult. Recently, the usefulness of diffusion-weighted MR imaging (DWI) in the diagnosis of pancreatic cancer has been reported in several studies. Purpose: To determine whether high-b-value DWI can distinguish pancreatic cancer from benign mass-forming chronic pancreatitis. Material and Methods: Twenty pancreatic cancers and four cases of mass-forming chronic pancreatitis were evaluated by high-b-value DWI (b=800 s/mm(2)). The signal intensity on DWI was visually evaluated, and the isotropic apparent diffusion coefficients (ADCs) were measured. Results: All twenty pancreatic cancers showed high signal intensity (18 showed very high, two showed slightly high) on DWI. None of the mass-forming chronic pancreatitis cases showed very high intensity (three showed iso to low, one showed slightly high) on DWI. The ADCs in the pancreatic cancer and mass-forming chronic pancreatitis were 1.38 +/- 0.32x10(-3) mm(2)/s and 1.00 +/- 0.18x10(-3) mm(2)/s, respectively (P<0.05). Conclusion: On high-b-value DWI, most pancreatic cancers showed very high signal intensity, and may hence be distinguished from benign mass-forming chronic pancreatitis based on our preliminary results.