MR Imaging of Pancreatic Lesions

Aim: The aim of this work was to evaluate the role of MRI in differentiating between benign and malignant pancreatic lesions and its correlation with histopathological results as the reference standard.

Patients and Methods: This MRI study included 30 patients, 17 females and 13 males with a mean age 50 years. Sixteen patients had malignant masses (14 patients were adenocarcinoma, one patient was lymphoma and one patient was metastasis) and 14 patients had benign masses (7 patients were pancreatic pseudocysts, two patients were pancreatic abscesses, three patients were simple cysts and two patients were focal pancreatitis). The main clinical symptom was abdominal pain and most of masses were located in the head of the pancreas.

Results: In our study, 25 cases of the 30 patients showed increased intensity at T2-weighted images. Most of malignant cases showed low or equal intensity on T1- and high intensity on T2-weighted images compared to normal pancreatic parenchyma. In our study, DW-MRI was performed on all subjects at b-values of 500 and 1000 s/mm2. Benign pancreatic masses as pancreatic pseudocyst, simple cyst and abscess show low signal intensities on DWI, however malignant pancreatic masses as adenocarcinoma, lymphoma and metastasis show high signal intensities on DWI with a cut-off value of 1.5 x10-3 s/mm2 for the differentiation of benign from malignant pancreatic masses by b-value 1000 s/mm2 with the sensitivity, specificity, PPV, NPV& p value were 100%, 83.33%, 100%, 88.88% and <0.001 respectively.

Conclusion: MRI plays an important role in the diagnosis of different pancreatic lesions and can assess the neoplastic pancreatic lesions with accurate detection of extension, nodal involvement and hepatic metastatic lesions. It also has a major role in differentiation between benign and malignant pancreatic lesions by the aids of DWI.