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PURPOSE To study the characteristics of acute necrotizing pancreatitis (ANP) in different age stages and their correlations with the clinical outcomes using magnetic resonance imaging (MRI). METHOD MRI of 716 patients with acute pancreatitis was retrospectively reviewed to assess the incidence and characteristics of ANP. On MRI, ANP was classified into three subtypes: extrapancreatic necrosis (EPN) alone, pancreatic necrosis (PN) alone and combined necrosis. The extent of necrosis was also quantified on MRI. All patients were divided into three age groups, that is, young,middle-aged and elderly groups, and these characteristics of ANP were compared among the three age groups. The endpoints of patients' clinical outcome were compared among different age groups and different characteristics of ANP. RESULTS Of the 716 patients, 129(18 %) were identified as ANP on MRI. The prevalence of ANP in the elderly group was the highest (28.9 %, p < 0.05). The patients in the middle-age and the elderly groups exhibited a higher risk of combined necrosis (56.9 %, 55.8 %; respectively), and elderly patients more frequently had extensive extrapancreatic involvement compared with young patients (65.9 % vs 21.4 %; p = 0.004); however, PN alone was more common in young patients. These characteristics of ANP were significantly bound up with clinical outcomes. CONCLUSIONS Different subtypes of ANP have different outcomes. More importantly, age needs to be considered as a factor of special concern in development of ANP.