Table 1.

Revised Atlanta Classification of Pancreatic and Peri-Pancreatic Fluid Collections

Type of collection	Time, wk	Location	Imaging appearance
Interstitial edematous pancreatitis
Acute peri-pancreatic fluid collection	≤4	Adjacent to pancreas, extrapancreatic only	Homogeneous, fluid attenuation, no liquefaction, not encapsulated
Pseudocyst	>4	Adjacent or distant to pancreas	Homogeneous, fluid attenuation, no liquefaction, encapsulated
Necrotizing pancreatitis
Acute necrotic collection	≤4	In parenchyma and/or extrapancreatic	Heterogeneous, nonliquefied material, variably loculated, not encapsulated
Walled-off necrosis	>4	In parenchyma and/or extrapancreatic	Heterogeneous, nonliquefied material, variably loculated, encapsulated

Adapted from Thoeni RF. Radiology 2012;262:751–764, with permission from Radiological Society of North America.⁸