Preoperative Identification of a Prognostic Factor for Pancreatic Neuroendocrine Tumors Using Multiphase Contrast-Enhanced Computed Tomography.

Abstract

To find predictive factors among computed tomography (CT) findings to identify pancreatic neuroendocrine tumors G2 of World Health Organization classification. Thirty-seven patients with pancreatic neuroendocrine tumors underwent multiphase contrast enhanced CT (unenhanced, arterial, pancreatic, portal and equilibrium phase), and attenuation values and imaging findings were examined. A receiver operating characteristic curve analysis was performed, and association between imaging findings and World Health Organization classification was evaluated. Mean CT attenuation value of NET G1 was significantly higher than that of NET G2 throughout the arterial, pancreatic, and portal phases. Receiver operating characteristic analysis according to tumor size revealed sensitivity: 83.3%, specificity: 92.0% and area under the curve (AUC): 0.853, whereas that of corrected true enhancement values in the pancreatic phase revealed sensitivity: 91.7%, specificity: 84.0% and AUC: 0.897, which showed the highest AUC. Specific CT findings, such as irregular tumor contour, vessel involvement, and cystic degeneration/necrosis, were significantly associated with NET G2, but not to the extent of CT attenuation value and tumor size. The CT enhancement in the pancreatic phase, and irregularity, vessel involvement, and cystic degeneration/necrosis were significant predictors of NET G2. These parameters might help in differentiating between NET G1 and G2, providing a basis for appropriate treatment.