Small solid tumors (< or = 2 cm) of the pancreas: relative accuracy and differentiation of CT and MR imaging.

Background/aims: To determine the relative accuracy of CT and MRI in characterization of solid pancreatic masses (< or = 2cm) and useful imaging appearance for differentiating small pancreatic duct adenocarcinoma (PDAC) from other small solid pancreatic neoplasms.

Methodology: CT and MRI scans of 46 patients with evidence of small pancreatic solid tumor were retrospectively evaluated, who underwent CT (n=30), MRI (n=4), or both (n=12). Two gastrointestinal radiologists independently recorded specific morphological features of tumors and the most likely diagnosis.

Results: With respect to specific histopathological characterization, CT and MRI were equally accurate. The mean number of correct diagnoses made by the two reviewers was 37.5 (88.4%) of 42 cases for CT compared to 12 (75%) of 16 cases for MRI (p=0.388). Location in the pancreatic head (p=0.000), presence of dilatation of MPD (p=0.000), presence of dilatation of CBD (p=0.001) and enhancement pattern (p=0.000) were statistically significant for differentiating PDAC from the other small solid pancreatic tumors, while pancreatic atrophy (p=0.069) was statistically inadequate for differentiation, although it gave a 96.4% specificity for the diagnosis of PDAC.

Conclusions: CT and MRI are similarly accurate in the characterization of small solid pancreatic tumors. Small PDAC has characteristic CT and MRI findings that differentiate it from other small solid tumors.