 Introduction/Background Acute pancreatitis (AP), an inflammatory process affecting the pancreas, is the third most frequent gastrointestinal cause of hospital admissions in the United States [1]. AP results in approximately 300,000 hospital admissions each year, with associated costs of approximately $2.6 billion [1,2]. The incidence of AP is increasing and is estimated at 40 per 100,000 people. The clinical diagnosis of AP requires 2 of the following 3 features: 1) abdominal pain consistent with AP (acute onset of persistent, severe, epigastric pain often radiating to the back); 2) serum lipase or amylase levels at least 3 times the upper limits of normal; and 3) characteristic findings of AP on contrast-enhanced CT, MRI, or transabdominal ultrasound (US) [3]. As such, if the abdominal pain is characteristic of pancreatitis and the amylase or lipase levels are not elevated to at least 3 times above normal, imaging is required for diagnosis. Imaging is also performed in AP to investigate the etiology, complications, and extent of disease. Imaging AP requires an understanding of the disease subtypes, evolution, and associated complications. Familiarity with the appropriate radiologic nomenclature as defined by the Atlanta symposium in 1992 and, more recently, modified by the Acute Pancreatitis Classification Working Group in 2008 is also essential [3]. Special Imaging Considerations Radiographs Conventional radiographs and upper gastrointestinal series currently have a limited role in the evaluation of a patient with AP. Radiographic signs of AP, such as dilated air-filled duodenum or jejunum, are secondary and nonspecific. Similarly, thickened rugal or duodenal folds or dilation of the duodenal C-loop are nonspecific findings of AP seen on upper gastrointestinal series or follow-through studies.
Acute Pancreatitis.  Introduction/Background Acute pancreatitis (AP), an inflammatory process affecting the pancreas, is the third most frequent gastrointestinal cause of hospital admissions in the United States [1]. AP results in approximately 300,000 hospital admissions each year, with associated costs of approximately $2.6 billion [1,2]. The incidence of AP is increasing and is estimated at 40 per 100,000 people. The clinical diagnosis of AP requires 2 of the following 3 features: 1) abdominal pain consistent with AP (acute onset of persistent, severe, epigastric pain often radiating to the back); 2) serum lipase or amylase levels at least 3 times the upper limits of normal; and 3) characteristic findings of AP on contrast-enhanced CT, MRI, or transabdominal ultrasound (US) [3]. As such, if the abdominal pain is characteristic of pancreatitis and the amylase or lipase levels are not elevated to at least 3 times above normal, imaging is required for diagnosis. Imaging is also performed in AP to investigate the etiology, complications, and extent of disease. Imaging AP requires an understanding of the disease subtypes, evolution, and associated complications. Familiarity with the appropriate radiologic nomenclature as defined by the Atlanta symposium in 1992 and, more recently, modified by the Acute Pancreatitis Classification Working Group in 2008 is also essential [3]. Special Imaging Considerations Radiographs Conventional radiographs and upper gastrointestinal series currently have a limited role in the evaluation of a patient with AP. Radiographic signs of AP, such as dilated air-filled duodenum or jejunum, are secondary and nonspecific. Similarly, thickened rugal or duodenal folds or dilation of the duodenal C-loop are nonspecific findings of AP seen on upper gastrointestinal series or follow-through studies.