Abstract
PurposeTo assess qualitative and quantitative imaging features on enhanced CT that may differentiate pancreatic neuroendocrine tumors (PNETs) from pancreatic renal cell carcinoma (RCC) metastases.MethodsThis IRB-approved multi-center retrospective case-control study compared 43 resected PNETs and 28 resected RCC metastases with pre-operative enhanced CT identified consecutively between 2003 and 2017. Two blinded radiologists (R1/R2) independently assessed tumor location, attenuation (relative to pancreas), composition (solid/cystic/mixed), homogeneity (homogeneous/heterogeneous), calcification, multiplicity, and for main pancreatic duct (MPD) dilation. Tumors were segmented for quantitative texture analysis. Data were analyzed with Chi square, logistic regression, and receiver operating characteristic (ROC). Inter-observer agreement was assessed (Cohen's kappa).ResultsThere was no difference in age, gender, location, attenuation, or composition (P>0.05) between groups. PNETs were larger than RCC metastases (3723mm vs. 26 +/- 21mm, P=0.038), more frequently solitary (P<0.001), subjectively more heterogeneous (P=0.033/0.144, R1/R2), and associated with calcification (P=0.002/0.004) and MPD dilation (P=0.025/0.006). Agreement for subjective features was moderate-to-almost perfect (K=0.4879-0.9481). Quantitative texture analysis showed higher entropy in PNETs (6.32 +/- 0.49 versus 5.96 +/- 0.53; P=0.004) with no difference in other features studied (P>0.05). Entropy had ROC area under the curve for diagnosis of PNET of 0.77 +/- 0.06, with optimal sensitivity/specificity of 71.4/79.1%.ConclusionsCompared to pancreatic RCC metastases, PNETs are larger, more frequently solitary, contain calcification, show MPD dilation, and are subjectively and quantitatively more heterogeneous tumors.