Nonfunctioning endocrine tumors of the pancreas: possibilities of spiral CT characterization

The aim of this study was to assess the ability of spiral CT to adequately characterize the nonfunctioning endocrine tumors (NFETs) of the pancreas, d istinguishing this lesion from the other pancreatic tumors. The spiral CT e xaminations of i cases of histologically proven NFETs, along with those of 29 cases of other pancreatic tumors and tumor-like lesions, were retrospect ively reviewed in a blinded fashion by two radiologists, in order to correc tly classify the lesions, highlighting the typical signs reported in the li terature. Discordant cases were further analyzed in the presence of a third radiologist. The final diagnosis was acquired by means of a majority or ov erall consensus. The histopathologic examination was considered the gold st andard. The sensitivity, specificity, and positive and negative predictive values of CT were calculated. After the consensus evaluation, the correct d iagnosis was reached in 72 % of cases, with 10% of nonspecific diagnoses of solid pancreatic tumor and 18 % of wrong diagnoses. The sensitivity and sp ecificity of spiral CT in identifying NFETs were 66.6 and 82.7 %, respectiv ely. The positive and negative predictive values were 73.7 and 77.4%, respe ctively. In up to 70% of cases the NFET demonstrates a typical aspect of a mass hyperdense in the arterial contrastographic phase eventually associate d with hyperdense hepatic metastases in more than half of the patients. Thi s finding does allow the diagnosis of NFET but without certainty indeed, si nce other tumors can show a similar densitometric behavior and among them p articularly the ductal adenocarcinoma. On the other hand, both the solid, h ypovascularized NFETs, and the cystic form, cannot be differentiated from t he other solid and cystic tumors of the pancreas.