Note: This copy is for your personal non-commercial use only. To order presentation-ready copies for distribution to your colleagues or clients, contact us at www.rsna.org/rsnarights. GASTROINTESTINAL IMAGING 1218 Necrotizing Pancreatitis: Diagnosis, Imaging, and Intervention 1 Acute necrotizing pancreatitis is a severe form of acute pancreatitis characterized by necrosis in and around the pancreas and is associ- ated with high rates of morbidity and mortality. Although acute in- terstitial edematous pancreatitis is diagnosed primarily on the basis of signs, symptoms, and laboratory test findings, the diagnosis and severity assessment of acute necrotizing pancreatitis are based in large part on imaging findings. On the basis of the revised Atlanta classification system of 2012, necrotizing pancreatitis is subdivided anatomically into parenchymal, peripancreatic, and combined sub- types, and temporally into clinical early (within 1 week of onset) and late (>1 week after onset) phases. Associated collections are categorized as “acute necrotic” or “walled off” and can be sterile or infected. Imaging, primarily computed tomography and magnetic resonance imaging, plays an essential role in the diagnosis of necro- tizing pancreatitis and the identification of complications, including infection, bowel and biliary obstruction, hemorrhage, pseudoan- eurysm formation, and venous thrombosis. Imaging is also used to help triage patients and guide both temporizing and definitive management. A “step-up” method for the management of necrotiz- ing pancreatitis that makes use of imaging-guided percutaneous catheter drainage of fluid collections prior to endoscopic or surgical necrosectomy has been shown to improve clinical outcomes. The authors present an algorithmic approach to the care of patients with necrotizing pancreatitis and review the use of imaging and interven- tional techniques in the diagnosis and management of this patho- logic condition. © RSNA, 2014 • radiographics.rsna.org JeffreyY. Shyu, MD Nisha I. Sainani, MD V. Anik Sahni, MD Jeffrey F. Chick, MD Nikunj R. Chauhan, MD Darwin L. Conwell, MD Thomas E. Clancy, MD Peter A. Banks, MD Stuart G. Silverman, MD Abbreviations: ANC = acute necrotic collec- tion, APFC = acute peripancreatic fluid col- lection, CBD = common bile duct, ERCP = endoscopic retrograde cholangiopancreatogra- phy, MRCP = MR cholangiopancreatography, PCD = percutaneous catheter drainage, WON = walled-off necrosis RadioGraphics 2014; 34:1218–1239 Published online 10.1148/rg.345130012 Content Codes: 1 From the Department of Radiology, Division of Abdominal Imaging and Intervention (J.Y.S., N.I.S., V.A.S., J.F.C., N.R.C., S.G.S.), Depart- ment of Medicine, Division of Gastroenterology, Hepatology and Endoscopy (D.L.C., P.A.B.), and Department of Surgery, Division of Surgi- cal Oncology (T.E.C.), Brigham and Women’s Hospital, Harvard Medical School, 75 Francis St, Boston, MA 02115. Presented as an educa- tion exhibit at the 2012 RSNA Annual Meeting. Received July 1, 2013; revision requested Octo- ber 17 and received January 1, 2014; accepted March 7. For this journal-based SA-CME ac- tivity, the authors, editor, and reviewers have disclosed no relevant relationships. Address correspondence to N.I.S. (e-mail: nsainani@ partners.org). After completing this journal-based SA- CME activity, participants will be able to: ■ Recognize the imaging manifestations of necrotizing pancreatitis and related complications, as well as the terminology used in the recently revised Atlanta clas- sification scheme. ■ Describe the role of imaging in the management of necrotizing pancreatitis and related complications. ■ Discuss current concepts in the man- agement of necrotizing pancreatitis, with an emphasis on the rationale and role of interventional radiology. See www.rsna.org/education/search/RG. SA-CME LEARNING OBJECTIVES Introduction Acute pancreatitis results in approximately 300,000 hospital admis- sions in the United States each year, at a cost of approximately $2.2 billion (1–3). This disease entity is divided into two morphologic subtypes: interstitial edematous pancreatitis and necrotizing pancre- atitis. Necrotizing pancreatitis, the more severe form, is defined as necrosis of the pancreatic parenchyma with or without necrosis of the peripancreatic tissues. It occurs as a complication in 20%–30% of patients with acute pancreatitis and historically has been associ- ated with high rates of morbidity (34%–95%) and mortality (2%– 39%) (4,5). Mortality within the first 2 weeks of onset is most often due to systemic inflammatory response syndrome, which is an exag- gerated inflammatory response associated with systemic organ dys-