Diagnostic accuracy of MRI for preoperative staging of pancreatic carcinoma: Tendency for understaging

Objective: To evaluate the diagnostic accuracy of magnetic resonance imaging (MRI) for preoperative staging in pancreatic carcinoma. Materials and Methods: MRI investigations, including MR-angio and MR-cholangiopancreatography (MRCP) of 19 patients who underwent surgery for pancreatic carcinoma were retrospectively evaluated by two radiologists. The size, localization of the tumor and possible infiltration of neighboring organs, as well as the presence of enlarged lymph nodes, were determined to define a preoperative, radiological TN stage. Lymph node metastasis was defined as peripancreatic lymphoma greater than 10 mm. Our findings were correlated to postoperative diagnosis. Results: The T-stage was correctly evaluated in 52.6% of the cases (10/19). Understaging took place in 31.6% (6/19) and overstaging in 15.8% (3/19). In three cases of understaging, a micro-infiltration of the peripancreatic tissue was not visible in MRI. Pathologically enlarged lymph nodes were correctly found in 63.2% of the cases (12/19). Overstaging took place in 21.1 % of the cases (4/19) and understaging in 15.8% (3/19). Conclusion: MRI for preoperative staging of pancreatic carcinoma showed a tendency to understage tumor size in this study population. Especially in cases of small tumor size, micro-infiltration of peripancreatic tissue or the common bile duct may not be detected by MRI. Concerning N-stage, the 95% confidence interval reveals a distribution of over- and understaged.