Baseline CT-based Radiomic Features Aid Prediction of Nodal Positivity after Neoadjuvant Therapy in Pancreatic Cancer

Purpose: To study the association between CT-derived textural features of pancreatic cancer and patient outcome. Materials and Methods: This retrospective study evaluated 54 patients (median age, 62 years [range, 40–88 years]; 32 men) with pancreatic cancer who underwent chemoradiation followed by surgical resection and lymph node dissection from May 2012 to June 2016. Three-dimensional segmentation of the pancreatic tumor was performed on baseline dual-energy CT images: 70-keV pancreatic pa-renchymal phase (PPP) images and iodine material density images. Then, 15 and 19 radiomic features were extracted from each phase, respectively. Logistic regression with elastic net regularization was used to select textural features associated with outcome, and receiver operating characteristic analysis evaluated feature performance. Survival curves were generated using the Kaplan-Meier method. Results: The feature of integral total (* T), representing the mean intensity in Hounsfield units times the contour volume in milliliters of PPP imaging (hereafter, “* T (HU·mL) (PPP)”), is inversely associated with posttherapy pathologic lymph node (ypN) category. A threshold * T (HU·mL) (PPP) less than 507.85 predicted ypN1–2 classification with 96% sensitivity, 34% specificity, and area under the curve of 0.61. Patients with an * T (HU·mL) (PPP) of less than 507.85 had decreased overall survival (median, 2.8 years) compared with patients with an * T (HU·mL) (PPP) of 507.85 or greater (one event at 3.4 years) (P = .006). Patients with an * T (HU·mL) (PPP) of less than 507.85 had decreased progression-free survival (median, 1.5 years) compared with patients with an * T (HU·mL) (PPP) of 507.85 or greater (median, 2.7 years) (P = .001). Conclusion: A CT-based radiomic signature may help predict ypN category in patients with pancreatic cancer.