The imaging features of extrapancreatic perineural invasion (EPNI) in pancreatic Cancer：A comparative retrospective study

Extrapancreatic perineural invasion (EPNI) is a risk factor for the prognosis of patients with pancreatic cancer. Few reliable clinical indicators can be used to evaluate EPNI.We reviewed clinicopathological information of pancreatic cancer patients received radical surgery in our center from 2014 to 2019. The minimum distance between the tumor boundary and celiac artery (CA), superior mesenteric arteria (SMA) was respectively measured on enhanced-contrast CT images. Receiver Operating Characteristic (ROC) analysis was used to evaluate the diagnostic efficacy, and the optimal cut-off value was determined by Youden index. The latter was used as a diagnostic indicator for imaging perineural invasion (iPNI). K-M method and Cox risk regression model were applied to analyze the prognostic value of iPNI.A total of 384 patients were enrolled in this study. ROC analysis showed the minimum distance is an efficient indicator, and the best cut-off value 6.5 mm provided 71.63% sensitivity and specificity 84.31%. Cox regression model showed that iPNI was an independent risk factor for disease-free survival (DFS) and overall survival (OS). Subgroup analysis indicated that patients with larger tumor size and iPNI positive suggested a worse prognosis.The minimum distance between tumor boundary and arteries is an efficient imaging indicator for diagnosing EPNI. iPNI is an independent risk factor for DFS and OS. The novel typing method based on plexus pancreaticus capitalis (PLX) potentially invaded may have guiding significance for extent of dissection.