This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Radiology
Confluent areas of pancreatic parenchyma that do not demonstrate enhancement after the administration of intravenous (IV) contrast material is known as: 
Select and explain. 
A. Pseudocyst, B. walled off pancreatic necrosis, C. Acute peripancreatic fluid collection, D. Pancreatic necrosis
D: Pancreatic necrosis
Answer: D: Pancreatic necrosis 
Explanation: Pancreatic necrosis is defined as confluent areas of pancreatic parenchyma that do not demonstrate enhancement after the administration of (IV) contrast material. Pseudocyst is with a well defined wall with fluid inside. Walled off pancreatic necrosis happens after 4 weeks of acute pancreatic necrosis. Acute peripancreatic fluid collection is outside the pancreas. Ref: ACR Appropriateness Criteria,Acute Pancreatitis.