Acute pancreatitis can be classified as edematous, interstitial pancreatitis (mild) or necrotizing pancreatitis (severe). Although most attacks of acute pancreatitis are mild and patients recover relatively quickly, severe necrotizing pancreatitis is associated with a high rate of morbidity and a significant mortality. Rarely, there are patients who present with early severe acute pancreatitis, consisting of extensive pancreatic necrosis and organ failure at admission.

Knowing the severity of pancreatitis helps determine the management and predicted outcome. Contrast-enhanced CT is the imaging modality of choice to assess the severity of acute pancreatitis and for detecting complications related to acute pancreatitis. Contrast-enhanced CT distinguishes between edematous and necrotizing pancreatitis because areas of necrosis and exudate do not enhance. CT is more accurate than ultrasonography for the diagnosis of severe pancreatic necrosis. It takes time for pancreatic necrosis to develop and is unlikely to be seen by contrast CT on the first day of illness. It is, therefore, more helpful to obtain a contrast CT if the initial diagnosis is unclear, if a child with acute pancreatitis is deteriorating, or is determined clinically or by outcome severity score to have severe pancreatitis. A radiologist is able to assign a CT severity index score based on the percentage of necrosis seen on contrast enhanced CT, which is used to predict outcome and dictate subsequent management in adults.