Utility of the portal venous phase for diagnosing pancreatic necrosis in acute pancreatitis using the CT severity index

PurposeThe purpose of the study was to evaluate the value of portal venous phase (PVP) images in the diagnosis of pancreatic necrosis in patients with acute pancreatitis using computed tomography severity index (CTSI).MethodsThis retrospective study was approved by our Institutional Review Board, and written informed consent was waived. Dynamic contrast-enhanced CT images, with the pancreatic parenchymal phase (PPP) and the PVP, were obtained from 56 consecutive patients with acute pancreatitis. Two radiologists reviewed two sets of images, namely PPP images alone (image set A) and combined PPP and PVP images (image set B) to evaluate the CTSI. Cases were categorized as necrotizing pancreatitis if ensuing walled-off necrosis formation was identified 4weeks after onset of symptoms. The relationship between pancreatic necrosis and CTSI was compared between image sets A and B. Logistic regression analysis was performed to evaluate the significance of clinical and radiological factors associated with the diagnosis of pancreatic necrosis.ResultsPancreatic necrosis was confirmed in 14 out of 56 (25%) patients. The area under the receiver-operating-characteristic curve (AUC) for the diagnosis of pancreatic necrosis was 0.70 and 0.78 for image sets A and B, respectively. The AUC for image set B was significantly greater than that for image set A (P=0.0002). Logistic regression analysis demonstrated that among clinical and radiological factors tested, CTSI for image set B was independently correlated with pancreatic necrosis (P=0.025).ConclusionsCombined PPP and PVP images significantly improved the diagnostic accuracy of pancreatic necrosis following acute pancreatitis.