CT Surveillance for Local Recurrence After Pancreatic Cancer Resection: Evaluation of Imaging Findings From the SAR...

BACKGROUND. A Society of Abdominal Radiology (SAR) Pancreatic Ductal Adenocarcinoma (PDAC) Disease-Focused Panel (DFP) consensus statement described findings suspicious for local recurrence (LR) on surveillance imaging after PDAC resection. OBJECTIVE. The purpose of this study was to evaluate interreader agreement and predictive utility of potential imaging findings of LR on serial surveillance CT examinations after the Whipple procedure for PDAC, using the SAR PDAC DFP consensus statement. METHODS. This retrospective study included 126 patients (mean age, 68.5 ± 10.3 [SD] years; 72 men, 54 women) who underwent the Whipple procedure for PDAC between January 2009 and December 2014. Three radiologists independently reviewed baseline and subsequent postoperative contrast-enhanced abdominopelvic CT examinations performed within 2 years after surgery, evaluating features in the SAR PDAC DFP consensus statement relating to surgical bed stranding, surgical bed soft tissue, vessel encasement, main pancreatic duct dilatation, and ascites. Interreader agreement was calculated. The reference standard for LR development within 2 years after surgery incorporated all available information. The frequencies of imaging features were calculated for the recurrence examinations (i.e., the first surveillance examinations indicating LR). For baseline postoperative examinations, associations of the imaging features with eventual LR development were assessed by multivariable logistic regression analysis. RESULTS. LR developed within 2 years after surgery in 81 of the 126 patients. For both the baseline and subsequent examinations, agreement for stranding and agreement for soft-tissue morphology were poor, for vessel encasement was fair, for soft tissue and ascites were moderate, and for main pancreatic duct dilatation was substantial. On recurrence examinations, across readers, new or increased stranding was present in 27-77%; new or increased soft tissue, 80-88%; soft tissue with vessel encasement and luminal narrowing, 36-59%; new or increased main pancreatic duct dilatation, 25-26%; and new or increased ascites, 20-23%. On baseline postoperative examinations, independent predictors of eventual LR were soft tissue for all three readers (OR = 2.78-6.85) and stranding for reader 1 (OR = 3.59); main pancreatic duct dilatation and ascites were not independent predictors of LR for any reader. CONCLUSION. This study highlights the role of soft tissue, particularly when associated with vessel encasement and luminal narrowing, in raising suspicion for LR after PDAC resection. CLINICAL IMPACT. This study supports the SAR PDAC DFP consensus statement, while highlighting opportunities for continued optimization.